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The Children of Atomic Bomb Survivors: A Genetic Study (1991)

Chapter: The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki

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Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

THE EFFECT OF EXPOSURE TO THE ATOMIC BOMBS ON PREGNANCY TERMINATION IN HIROSHIMA AND NAGASAKI

By

J.V.NEEL AND W.J.SCHULL

DEPARTMENTOF HUMAN GENETICS UNIVERSITYOF MICHIGAN

in collaboration with

R.C.ANDERSON

W.H.BORGES

R.C.BREWER

S.KITAMURA

M.KODANI

D.J.MCDONALD

N.E.MORTON

M.SUZUKI

K.TAKESHIMA

W.J.WEDEMEYER

J.W.WOOD

S.W.WRIGHT

J.N.YAMAZAKI

ATOMIC BOMB CASUALTY COMMISSION

HIROSHIMA, JAPAN

Publication No. 461

NATIONAL ACADEMYOF SCIENCES—NATIONAL RESEARCH COUNCIL

WASHINGTON 25, D.C.

1956

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

LIBRARYOF CONGRESS CARD CATALOGUE No. 56–60060

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

TABLE OF CONTENTS

   

I. BACKGROUND

 

1

   

1.1 THE GENERAL ADMINISTRATIVE FRAMEWORK OF THE STUDY

 

1

   

1.2 THE BEGINNINGS OF THE GENETICS PROGRAM

 

2

   

1.3 THE EARLY JAPANESE EFFORTS ALONG THESE LINES

 

2

   

1.4 SCIENTIFIC AND ADMINISTRATIVE CONSIDERATIONS SHAPING THE NATURE OF THE PROGRAM IN JAPAN

 

3

   

1.5 LOCAL CONSIDERATIONS SHAPING THE NATURE OF THE PROGRAM IN JAPAN

 

3

   

II. THE PLAN

 

5

   

2.1 PREGNANCY REGISTRATION

 

5

   

2.2 SPECIAL STUDIES ON ABNORMAL TERMINATIONS

 

9

   

2.3 THE “10-PER CENT SAMPLE”

 

9

   

2.4 THE ACCURACY AND REPRODUCIBILITY OF THE ANAMNESTIC DATA OBTAINED ON THE GENETICS SHORT FORM AND THE GENETICS LONG FORM.

 

9

   

2.5 THE AUTOPSY PROGRAM

 

14

   

2.6 THE COLLECTION OF DATA ON INFANTS AGED 9 MONTHS

 

14

   

2.7 THE PROCESSING OF THE DATA

 

18

   

2.8 THE STUDY OF SPONTANEOUS ABORTIONS

 

18

   

2.9 CYTOGENETIC EFFECTS OF THE ATOMIC BOMBS

 

18

   

2.10 THE DECISION TO DISCONTINUE WORK IN KURE

 

18

   

2.11 THE TERMINATION OF THE PROGRAM IN JANUARY, 1954

 

19

   

2.12 ACKNOWLEDGMENTS

 

19

   

III. A COMPARISON OF HIROSHIMA AND NAGASAKI

 

21

   

3.1 THE PEOPLING OF JAPAN; POSSIBLE DIFFERENCES BETWEEN THE INHABITANTS OF HONSHU AND KYUSHU

 

21

   

3.2 NON-JAPANESE ELEMENTS IN THE TWO CITIES

 

21

   

3.2.1 EARLY NAGASAKI CONTACTS WITH THE WEST

 

21

   

3.2.2 THE DUTCH ON DESHIMA

 

22

   

3.2.3 FROM THE REOPENING OF JAPAN TO WORLD WAR II

 

22

   

3.3 THE BIOLOGICAL INFLUENCE OF “FOREIGNERS” ON NAGASAKI AND HIROSHIMA

 

23

   

3.4 THE DIFFERENT IMPACTS OF THE ATOMIC BOMBS ON THE TWO CITIES.

 

28

   

3.4.1 TYPES OF BOMBS

 

28

   

3.4.2 EFFECTS OF THE BOMBS ON THE TWO CITIES

 

28

   

3.5 THE DEVELOPMENT OF THE ABCC PROGRAM IN THE TWO CITIES

 

29

   

IV. THE CRITERIA OF RADIATION EMPLOYED IN THE STUDY

 

33

   

4.1 THE COMPLICATED NATURE OF THE INJURIES SUSTAINED BY SOME SURVIVORS; “DISASTER EFFECT” VS. “RADIATION EFFECT”

 

33

   

4.2 THE QUESTION OF RESIDUAL RADIATION FOLLOWING AN ATOMIC BOMBING

 

33

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
   

4.3 FACTORS DETERMINING THE NATURE OF THE RADIATION DATA COLLECTED IN THIS STUDY

 

34

   

4.3.1 THE SYNDROME OF RADIATION SICKNESS DUE TO WHOLE-BODY IRRADIATION

 

34

   

4.3.2 THE RELATION BETWEEN DISTANCE FROM THE HYPOCENTER AND RADIATION DOSAGE

 

36

   

4.3.3 THE ROLE OF SHIELDING IN DETERMINING RADIATION DOSE

 

36

   

4.4 THE TYPE OF RADIATION DATA COLLECTED IN THIS STUDY

 

38

   

4.5 THE RELATION BETWEEN DISTANCE, SHIELDING, AND SYMPTOMS IN THESE DATA

 

41

   

4.6 FACTORS CONTRIBUTING TO THE VALIDITY OF THE RADIATION HISTORIES

 

44

   

4.7 DEFINITION OF RADIATION CATEGORIES

 

44

   

4.8 CONSIDERATIONS IN THE ESTIMATION OF THE AVERAGE AMOUNT OF RADIATION RECEIVED BY PERSONS IN EACH OF THE FIVE RADIATION CATEGORIES

 

45

   

4.8.1 THE ESTIMATED DISTANCE-DOSAGE CURVE

 

46

   

4.8.2 THE OBSERVATIONS OF THE JOINT COMMISSION REGARDING LEUCOPENIA

 

46

   

4.8.3 THE PROPORTION OF INDIVIDUALS PROTECTED BY VARIOUS TYPES OF SHIELDING

 

50

   

4.9 ESTIMATES OF THE AVERAGE AMOUNT OF IRRADIATION RECEIVED BY INDIVIDUALS IN THE VARIOUS EXPOSURE CATEGORIES

 

50

   

V. THE COMPARABILITY OF IRRADIATION SUBCLASSES

 

53

   

5.1 CONSANGUINITY

 

53

   

5.2 AGE AND PARITY

 

55

   

5.3 ECONOMIC STATUS

 

59

   

5.4 FREQUENCY OF POSITIVE SEROLOGICAL TEST FOR SYPHILIS

 

61

   

5.5 FREQUENCY OF INDUCED ABORTIONS AND OF DILATATION AND CURETTAGE OF THE UTERUS (D AND C)

 

61

   

5.6 THE FREQUENCY OF REPEAT REGISTRATIONS

 

63

   

5.7 PARENTAL COOPERATION

 

63

   

5.8 LATE SEQUELAE OF EXPOSURE TO THE BOMBS

 

69

   

5.9 THE CHANGING PROPORTION OF CONTROL AND IRRADIATED FROM YEAR TO YEAR

 

69

   

5.10 THE BACKGROUND OF GROUP 1 INDIVIDUALS

 

71

   

5.11 SUMMARY

 

71

   

VI. STATISTICAL METHODS

 

72

   

6.1 THE PROBLEM AND THE GENERAL PLAN

 

72

   

6.2 INDICATORS OF RADIATION DAMAGE AND THE PROBLEM OF NON-OVERLAPPING MEASUREMENTS

 

72

   

6.3 CONCOMITANT VARIATION

 

73

   

6.4 REJECTED OBSERVATIONS

 

77

   

6.5 THE ANALYSIS OF THE ATTRIBUTE DATA

 

78

   

6.6 THE ANALYSIS OF THE MEASUREMENT DATA

 

82

   

6.7 SOME FURTHER PROBLEMS

 

85

   

6.8 THE USE OF EXPOSED PERSONS AS CONTROLS

 

86

   

6.9 PRESENTATION OF MATERIAL

 

87

   

VII. ANALYSIS OF THE SEX RATIO DATA

 

88

   

7.1 THE TRAIT

 

88

   

7.2 THE GENETIC ARGUMENT FOR RADIATION-INDUCED CHANGES IN THE SEX RATIO

 

88

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
   

7.3 CONCOMITANT VARIATION INFLUENCING THE INDICATOR

 

89

   

7.4 THE DATA

 

89

   

7.5 SUMMARY

 

96

   

VIII. ANALYSIS OF THE MALFORMATION DATA

 

99

   

8.1 THE TRAIT

 

99

   

8.2 RELIABILITY OF DIAGNOSIS

 

99

   

8.3 THE GENETIC ARGUMENT FOR RADIATION-INDUCED CHANGES

 

104

   

8.4 CONCOMITANT VARIATION INFLUENCING THE INDICATOR

 

105

   

8.5 THE “AT-BIRTH” DATA

 

110

   

8.6 THE “9-MONTHS” DATA

 

115

   

8.7 ANALYSIS BY SPECIFIC MALFORMATION TYPE

 

117

   

8.8 SUMMARY

 

117

   

IX. ANALYSIS OF THE STILLBIRTH DATA

 

118

   

9.1 THE TRAIT

 

118

   

9.2 THE GENETIC ARGUMENT FOR RADIATION-INDUCED CHANGES

 

118

   

9.3 CONCOMITANT VARIATION KNOWN TO AFFECT THE STILLBIRTH RATE

 

118

   

9.4 THE DATA

 

124

   

9.5 SUMMARY

 

129

   

X. THE ANALYSIS OF THE BIRTHWEIGHT DATA

 

131

   

10.1 THE TRAIT

 

131

   

10.2 THE GENETIC ARGUMENT FOR IRRADIATION EFFECTS

 

131

   

10.3 CONCOMITANT VARIABLES KNOWN TO AFFECT BIRTHWEIGHT

 

131

   

10.4 THE DATA AND THEIR ANALYSIS

 

132

   

10.5 SUMMARY

 

150

   

XI. ANALYSIS OF THE DATA CONCERNING DEATH DURING THE NINE-MONTH PERIOD FOLLOWING DELIVERY

 

151

   

11.1 THE TRAIT

 

151

   

11.2 THE GENETIC ARGUMENT FOR RADIATION-INDUCED CHANGES IN THE NEONATAL DEATH RATE

 

151

   

11.3 CONCOMITANT VARIABLES KNOWN TO INFLUENCE THE OCCURRENCE OF A NEONATAL DEATH

 

152

   

11.4 THE DATA

 

157

   

11.5 SUMMARY

 

162

   

XII. THE ANALYSIS OF THE ANTHROPOMETRIC DATA

 

164

   

12.1 THE MEASUREMENTS OBTAINED AT NINE MONTHS

 

164

   

12.2 THE GENETIC ARGUMENT FOR IRRADIATION EFFECTS

 

164

   

12.3 CONCOMITANT VARIABLES KNOWN TO AFFECT GROWTH AND DEVELOPMENT DURING THE FIRST YEAR OF LIFE

 

164

   

12.4 THE DATA

 

165

   

12.4.1 THE MULTIVARIATE MEANS

 

168

   

12.4.2 THE EQUALITY OF THE GENERALIZED VARIANCES

 

175

   

12.4.3 WITHIN-CELL HETEROGENEITY

 

179

   

12.5 SUMMARY

 

179

   

XIII. THE AUTOPSY FINDINGS

 

184

   

13.1 THE RANDOMNESS OF THE HIROSHIMA AUTOPSIES

 

184

   

13.2 THE DATA

 

187

   

13.3 SUMMARY

 

191

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

LIST OF TABLES

Chapter II

 TABLE 2.1

 

Per Cent of All Registrations (Including Those Involving Parental Consanguinity) with At Least One Parent Heavily Exposed (Radiation Categories 4, 5)

 

19

Chapter III

 TABLE 3.1

 

Population Figures by Nationality for Foreigners Resident in Nagasaki City between 1864 and 1870

 

23

 TABLE 3.2

 

The “Foreign” and Total Population of Nagasaki City, and the “Foreign” Population of Nagasaki Prefecture, 1897–1923

 

24

 TABLE 3.3

 

The Ethnic Composition of the Foreign Component of Nagasaki City, for the Years 1910 and 1930

 

25

 TABLE 3.4

 

The Age Composition and Ethnic Status of the Total Foreign Population of Nagasaki in 1920, as well as of the Four Principal Ethnic Groups in This Population

 

26

Chapter IV

 TABLE 4.1

 

Frequency of Occurrence of Certain Symptoms in Persons Alive 20 or More Days Following the Atomic Bombings, as Related to Distance from the Hypocenter

 

35

 TABLE 4.2

 

The Effectiveness of Shielding in Protecting against Radiation Sickness in Hiroshima

 

37

 TABLE 4.3

 

Distribution by Distance and Shielding of Husbands of Wives Registering Pregnancies with the Genetics Program: Hiroshima

 

38

 TABLE 4.4

 

Distribution by Distance and Shielding of Wives Registering Pregnancies with the Genetics Program: Hiroshima

 

39

 TABLE 4.5

 

Distribution by Distance and Shielding of Husbands of Wives Registering Pregnancies with the Genetics Program: Nagasaki

 

40

 TABLE 4.6

 

Distribution by Distance and Shielding of Wives Registering Pregnancies with the Genetics Program: Nagasaki

 

41

 TABLE 4.7

 

The Definition of “Exposure Categories” to be Employed in This Analysis.

 

44

 TABLE 4.8

 

Distribution of Registered Births by Parental Exposure

 

45

 TABLE 4.9

 

The Findings of the Joint Commission in Hiroshima with Regard to the Occurrence of Epilation, Petechiae, and Leucopenia in Persons Falling into Various Exposure Categories

 

47

 TABLE 4.10

 

The Exposure Categories Defined by the Joint Commission, to be Applied to the Interpretation of Table 4.9

 

47

 TABLE 4.11

 

The Distribution of Leucocyte Values in Hiroshima Japanese Who Failed to Develop Epilation, Petechiae, or Gingivitis Following the Bombing, in Relation to Distance from Hypocenter and Type of Shielding

 

48

 TABLE 4.12

 

Proportions of Parents Exposed in the 1,800–2,500 Meter Ring Who Reported Various Types of Shielding

 

50

Chapter V

 TABLE 5.1

 

Frequency of Consanguineous Marriages (First Cousins, First Cousins Once Removed, Second Cousins) by City and Parental Exposure

 

54

 TABLE 5.2

 

Chi-Square Analysis of the Frequency of Consanguineous Marriages by City and Parental Exposure

 

55

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

 TABLE 5.3

 

Mean Maternal Age by City and Parental Exposure

 

56

 TABLE 5.4

 

Analysis of Variance: Mother's Age by City and Parental Exposure

 

57

 TABLE 5.5

 

The Distribution of Mean Squares for Maternal Age by City, Sex of Infant, and Parental Exposure

 

57

 TABLE 5.6

 

Mean Parity by City and Parental Exposure

 

58

 TABLE 5.7

 

Analysis of Variance: Parity by City and Parental Exposure

 

59

 TABLE 5.8

 

The Distribution of Mean Squares for Parity by City, Sex of Infant, and Parental Exposure

 

59

 TABLE 5.9

 

Economic Status by City and Parental Exposure

 

60

 TABLE 5.10

 

Chi-Square Analysis of the Distribution of Economic Statuses by City and Parental Exposure

 

61

 TABLE 5.11

 

Frequency of Positive Serology by Parental Exposure, City, and Group: “Zero” Parents Only

 

62

 TABLE 5.12

 

Chi-Square Analysis of the Frequency of Positive Serologies by City and Parental Exposure

 

63

 TABLE 5.13

 

Frequency of Mothers Reporting One or More Induced Abortions by Parental Exposure, City, and Time

 

64

 TABLE 5.14

 

Chi-Square Analysis of the Frequency of Mothers Reporting One or More Induced Abortions by Parental Exposure, City, and Time

 

66

 TABLE 5.15

 

Frequency of “Dilatation and Curettage” by Parental Exposure and City: Zero Terminations

 

67

 TABLE 5.16

 

Chi-Square Analysis of the Frequency of “Dilatation and Curettage” by Parental Exposure and City: Zero Terminations

 

68

 TABLE 5.17

 

Mean Number of Registered Pregnancies per Mother by Parental Exposure and City

 

68

 TABLE 5.18

 

Incidence of Leukemia in the Hiroshima Survivors of the Atomic Bombing as Related to Distance from the Hypocenter and the Presence of Severe Radiation Complaints (After Moloney and Kastenbaum, 1955)

 

70

 TABLE 5.19

 

The Frequency of Malformations by Year among the Offspring of Parents Neither of Whom Was Exposed to the Atomic Bombs

 

70

 TABLE 5.20

 

The Frequency of Stillbirths by Year among the Offspring of Parents Neither of Whom Was Exposed to the Atomic Bombs

 

71

Chapter VI

 TABLE 6.1

 

The Number of Infants Rejected from the Study, Tabulated by Reason for Rejection

 

77

 TABLE 6.2

 

An Accounting of the Number of Observations Considered at Representative Stages in the Analysis of the “At-Birth” Data, and the Number of Rejected Observations with the Cause of Rejection

 

79

 TABLE 6.3

 

An Accounting of the Number of Observations Considered at Representative Stages in the Analysis of the “9-Months” Data and the Number of Rejected Observations with the Cause of Rejection

 

79

Chapter VII

 TABLE 7.1

 

The Frequency of Male Births by Parental Exposure and City

 

90

 TABLE 7.2

 

Chi-Square Analysis of the Frequency of Male Births by City and Parental Exposure

 

91

 TABLE 7.3

 

Selected Comparisons Regarding the Effect of Irradiation on Sex Ratio

 

92

 TABLE 7.4

 

National Statistics of Livebirths, 1935–1952

 

94

 TABLE 7.5

 

The Frequency of Male Births among Infants Born After April, 1946 but Prior to June, 1948, by Parental Exposure

 

95

 TABLE 7.6

 

Chi-Square Analysis of the Frequency of Male Births among Infants Born After April, 1946 but Prior to June, 1948

 

95

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

 TABLE 7.7

 

The Frequency of Male Births by Parental Exposure and City, 1954– 1955

 

97

 TABLE 7.8

 

Chi-square Analysis of the Frequency of Male Births during the Years 1948–1955 by Time of Birth, City, and Parental Exposure

 

98

Chapter VIII

 TABLE 8.1

 

An Alphabetical Listing of Those Malformations Observed in This Study which Occurring Alone or in Combination with One Another Were Graded as Major Congenital Defect

 

100

 TABLE 8.2

 

The Types and Frequency of Various Major Congenital Malformations Observed at the Tokyo Red Cross Maternity Hospital during the Years 1922 through 1940

 

101

 TABLE 8.3

 

A Comparison, for Hiroshima and Nagasaki, of the Findings as Regards Major Congenital Malformation in Infants Examined at Approximately Age 9 Months, and in Those Same Infants When Examined Shortly After Birth

 

103

 TABLE 8.4

 

The Effect of Maternal Age at Fixed Parity on the Frequency of Malformed Infants

 

106

 TABLE 8.5

 

The Effect of Maternal Parity at Fixed Age on the Frequency of Malformed Infants

 

108

 TABLE 8.6

 

The Frequency of Malformed Infants by Parental Exposure, Sex of Infant, and City

 

111

 TABLE 8.7

 

The Frequency of Malformed Infants by Parental Exposure, City, and Maternal Age

 

113

 TABLE 8.8

 

Chi-Square Analysis of the Frequency of Congenitally Malformed Infants by Sex, City, and Parental Exposure

 

114

 TABLE 8.9

 

Chi-Square Analysis of the Frequency of Congenitally Malformed Infants by City, Maternal Age, and Parental Exposure

 

114

 TABLE 8.10

 

The Distribution of Frequency of Malformed Infants Classified by Mother's Age and Exposure Only

 

115

 TABLE 8.11

 

Chi-Square Analysis of the Effect of Mother's Exposure on the Frequency of Malformed Infants at Each of Five Different Age Levels

 

115

 TABLE 8.12

 

The Distribution by Maternal Exposure and Parity of Malformed Infants Born to Mothers of Ages 15–20

 

115

 TABLE 8.13

 

The Distribution of Frequency of Malformed Infants Classified by Mother's Age and Father's Exposure Only

 

115

 TABLE 8.14

 

The Frequency of Malformed Infants among All Infants Re-examined at 9 Months of Age, by City and Parental Exposure

 

116

 TABLE 8.15

 

Chi-Square Analysis of the Frequency of Malformed Infants at 9 Months of Age by City and Parental Exposure

 

116

 TABLE 8.16

 

The Distribution by Maternal Exposure of the Seven Most Common Major Congenital Malformations in the Japanese, Exclusive of Congenital Heart Disease

 

116

Chapter IX

 TABLE 9.1

 

Congenital Syphilis among Living Infants Born in Nagasaki in 1951: Incidence and Relation to Maternal Age (After Wright, S.W. et al., 1952)

 

119

 TABLE 9.2

 

The Effect of Maternal Age at Fixed Parity on the Frequency of Stillborn Infants

 

120

 TABLE 9.3

 

The Effect of Maternal Parity at Fixed Age on the Frequency of Stillborn Infants

 

122

 TABLE 9.4

 

Frequency of Stillbirths by Sex, Parental Exposure and City

 

125

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

 TABLE 9.5

 

Chi-Square Analysis of the Frequency of Stillbirths by Sex, Parental Exposure and City

 

127

 TABLE 9.6

 

The Frequency of Stillbirths by Parental Exposure, City and Parity

 

128

 TABLE 9.7

 

Chi-Square Analysis of the Frequency of Stillbirths by Parental Exposure, City and Parity

 

129

 TABLE 9.8

 

The Frequency of Stillbirths among Firstborn Infants by City and Paternal Exposure

 

129

 TABLE 9.9

 

The Frequency of Stillbirths among Firstborn Infants by Paternal Exposure and Maternal Age

 

130

Chapter X

 TABLE 10.1

 

Mean Birthweight by Parental Exposure, Sex and City

 

134

 TABLE 10.2

 

Analysis of Variance of Birthweight by Parental Exposure and City

 

135

 TABLE 10.3

 

The Distribution by Parental Exposure of the Weighted Mean Squares of Deviations

 

136

 TABLE 10.4

 

Analysis of Covariance of Birthweights: Males, Hiroshima

 

136

 TABLE 10.5

 

Tests of the Significance and Homogeneity of the Regressions of Birthweight on Maternal Age and Parity: Males, Hiroshima

 

137

 TABLE 10.6

 

Analysis of Variance on the Adjusted Birthweight Means: Males, Hiroshima

 

138

 TABLE 10.7

 

The Adjusted Birthweight Means: Males, Hiroshima

 

138

 TABLE 10.8

 

The Residual Mean Squares from the Individual Cell Regressions: Males, Hiroshima

 

139

 TABLE 10.9

 

Analysis of Covariance of Birthweights: Females, Hiroshima

 

139

 TABLE 10.10

 

Tests of the Significance and Homogeneity of the Regressions of Birthweight on Maternal Age and Parity: Females, Hiroshima

 

140

 TABLE 10.11

 

Analysis of Variance on the Adjusted Birthweight Means: Females, Hiroshima

 

140

 TABLE 10.12

 

The Adjusted Birthweight Means: Females, Hiroshima

 

141

 TABLE 10.13

 

The Residual Mean Squares from the Individual Cell Regressions: Females, Hiroshima

 

141

 TABLE 10.14

 

Analysis of Covariance of Birthweights: Males, Nagasaki

 

142

 TABLE 10.15

 

Tests of the Significance and Homogeneity of the Regressions of Birthweight on Maternal Age and Parity: Males, Nagasaki

 

142

 TABLE 10.16

 

Analysis of Variance on the Adjusted Birthweight Means: Males, Nagasaki

 

143

 TABLE 10.17

 

The Adjusted Birthweight Means: Males, Nagasaki

 

143

 TABLE 10.18

 

The Residual Mean Squares from the Individual Cell Regressions: Males, Nagasaki

 

144

 TABLE 10.19

 

Analysis of Covariance of Birthweights: Females, Nagasaki

 

144

 TABLE 10.20

 

Tests of the Significance and Homogeneity of the Regressions of Birthweight on Maternal Age and Parity: Females, Nagasaki

 

145

 TABLE 10.21

 

Analysis of Variance on the Adjusted Birthweight Means: Females, Nagasaki

 

145

 TABLE 10.22

 

The Adjusted Birthweight Means: Females, Nagasaki

 

146

 TABLE 10.23

 

The Residual Mean Squares from the Individual Cell Regressions: Females, Nagasaki

 

146

 TABLE 10.24

 

A Summary of the Salient Findings of the Covariance Analysis

 

147

 TABLE 10.25

 

The Distribution by Parental Exposure of the Residual Mean Squares After Removal of Variation Due to Year of Birth of the Infant: Males, Hiroshima

 

149

 TABLE 10.26

 

The Distribution by Parental Exposure of the Residual Mean Squares After Removal of Variation Due to Year of Birth of the Infant: Females, Hiroshima

 

149

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

 TABLE 10.27

 

The Distribution by Parental Exposure of the Residual Mean Squares After Removal of Variation Due to Year of Birth of the Infant: Males, Nagasaki

 

149

 TABLE 10.28

 

The Distribution by Parental Exposure of the Residual Mean Squares After Removal of Variation Due to Year of Birth of the Infant: Females, Nagasaki

 

149

Chapter XI

 TABLE 11.1

 

The Effect of Maternal Age at Fixed Parity on the Frequency of Neonatal Deaths

 

154

 TABLE 11.2

 

The Effect of Parity at Fixed Maternal Age on the Frequency of Neonatal Deaths

 

156

 TABLE 11.3

 

The Frequency of Neonatal Deaths by Parental Exposure, City and Sex of Infant

 

158

 TABLE 11.4

 

The Frequency of Neonatal Deaths by Parental Exposure, City and Parity

 

160

 TABLE 11.5

 

Chi-Square Analysis of the Frequency of Neonatal Deaths by Parental Exposure, City and Sex

 

161

 TABLE 11.6

 

Chi-Square Analysis of the Frequency of Neonatal Deaths by Parental Exposure, City and Parity

 

162

 TABLE 11.7

 

The Frequency of Deaths between Birth and Nine Months of Age by Parental Exposure and City

 

163

 TABLE 11.8

 

Analysis of the Frequency of Deaths between Birth and Nine Months of Age, by Parental Exposure and City

 

163

Chapter XII

 TABLE 12.1

 

Distribution of Mean Weight in Decagrams at 9 Months of Age by City, Sex and Parental Exposure

 

165

 TABLE 12.2

 

Distribution of Mean Height in Millimeters at 9 Months of Age by City, Sex and Parental Exposure

 

166

 TABLE 12.3

 

Distribution of Mean Head Girth in Millimeters at 9 Months of Age by City, Sex and Parental Exposure

 

167

 TABLE 12.4

 

Distribution of Mean Chest Girth in Millimeters at 9 Months of Age by City, Sex and Parental Exposure

 

168

 TABLE 12.5

 

Analysis of Dispersion (All Exposure Cells). (a) Sums of Squares and Cross Products of Deviations for the Two-Factor Interactions, (b) Mean Squares for Individual Analyses of Variance

 

169

 TABLE 12.6

 

Analysis of Dispersion (All Exposure Cells). (a) Sums of Squares and Cross Products of Deviations for Main Effects and Additivity. (b) Mean Squares for Individual Analyses of Variance (on Main Effects and Additivity). (c) Analysis of Dispersion Test, Wilks' (Using Bartlett's Approximation)

 

170

 TABLE 12.7

 

Estimates of Constants and Their Variances for Tests of Equality

 

171

 TABLE 12.8

 

A Summary of the Significance of Tests Comparing All Possible Pairs of Exposure for Each Parent with Respect to the Variables w, x, y, and z

 

172

 TABLE 12.9

 

Analysis of Dispersion (Only Those Cells Where Both Parents Were Exposed), (a) Sums of Squares and Cross Products of Deviations for the Two-Factor Interactions, (b) Mean Squares for Individual Analyses of Variance (on Two-Factor Interactions)

 

173

 TABLE 12.10

 

Analysis of Dispersion (Only Those Cells Where Both Parents Were Exposed), (a) Sums of Squares and Products of Deviations for Main Effects and Additivity. (b) Mean Squares for Individual Analyses of Variance for Main Effects and Additivity

 

174

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

 TABLE 12.11

 

Estimates of Constants and Their Variances for Test of Equality

 

175

 TABLE 12.12

 

Mean Product Matrices: Males, Hiroshima

 

176

 TABLE 12.13

 

Mean Product Matrices: Females, Hiroshima

 

176

 TABLE 12.14

 

Mean Product Matrices: Males, Nagasaki

 

177

 TABLE 12.15

 

Mean Product Matrices: Females, Nagasaki

 

177

 TABLE 12.16

 

Tests of the Homogeneity of the Variances of the Anthropometric Measurements Over All Exposure Cells, and Subdivisions Thereof, for Specified Sex and City

 

178

 TABLE 12.17

 

Tests of the Homogeneity of the Variances of the Anthropometric Measurements Over All Exposure Cells, and Subdivisions Thereof, for Specified Sex and City

 

178

 TABLE 12.18

 

Test of the Generalized Variances on the Anthropometric Measurements by Specified Sex and City

 

179

 TABLE 12.19

 

Analysis of Dispersion, with Age at Examination Included as a Way of Classification (All Exposure Cells), (a) Sums of Squares and Cross Products of Deviations for the Two-Factor Interactions, (b) Mean Squares for Individual Analyses of Variance

 

180

 TABLE 12.20

 

Analysis of Dispersion with Age at Examination Included as a Way of Classification, (a) Sums of Squares and Products of Deviations for Main Effects and Additivity. (b) Mean Squares for Individual Analyses of Variance for Main Effects and Additivity

 

181

 TABLE 12.21

 

Estimates of Constants and Their Variances for Tests of Equality

 

182

 TABLE 12.22

 

A Summary of the Significance Tests Comparing All Possible Pairs of Exposure for Each Parent with Respect to the Variables x, y, w, and z, after Allowance Is Made for Age at Examination

 

183

Chapter XIII

 TABLE 13.1

 

A. The Randomness of the Distribution of Autopsied Infants by Sex of Infant and Parental Exposure. B. Chi-Square Analysis of the Frequency of Autopsy by Sex of Infant and Parental Exposure

 

185

 TABLE 13.2

 

Mean Maternal Age of Infants Stillborn or Dying during the First Six Days of Life by Sex of Infant, Parental Exposure and the Occurrence of Autopsy

 

186

 TABLE 13.3

 

The Distribution of Economic Status among Autopsied and Non-Autopsied Infants

 

186

 TABLE 13.4

 

The Distribution of Positive Serologies by Parental Exposure among Autopsied and Non-Autopsied Infants

 

187

 TABLE 13.5

 

The Distribution by Parental Exposure of Infants Born in Hiroshima and Found to be Grossly Abnormal at Autopsy

 

188

 TABLE 13.6

 

The Distribution by Exposure Class of the Exposed Parents Given in Table 13.5

 

188

 TABLE 13.7

 

Hayashi's Data on Congenital Abnormalities in Relation to Exposure of Parents (After Sevitt, 1955)

 

189

 TABLE 13.8

 

A Comparison of the Exposure Distribution of Hayashi's Data and That of the Atomic Bomb Casualty Commission Collected in Nagasaki

 

190

 TABLE 13.9

 

Distribution by Exposure Class of Exposed Parents Whose Infants Came to Autopsy at ABCC in Nagasaki

 

190

Chapter XIV

 TABLE 14.1

 

A Summarization of the Comparisons of the Various Indicators with Parental Exposure When (a) All Exposure Cells Are Considered, and (b) Only Those Cells Where Both Parents Were Exposed Are Considered

 

195

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

 TABLE 14.2

 

The Effect of Irradiation of Male Mice on the Sex Ratio of Offspring Conceived during the Post-Sterile Period (After Hertwig, 1938)

 

200

 TABLE 14.3

 

The Sex Ratio among Livebirths and Fetal Deaths in the Study of Macht and Lawrence (1955)

 

201

 TABLE 14.4

 

The Effect of Irradiation of Male Mice on the Frequency of Stillbirths among Offspring Conceived during the Post-Sterile Period (After Hertwig, 1938)

 

202

Chapter XV

 TABLE 15.1

 

Frequency of Occurrence of Spontaneous “Visible” Mutations in Drosophila and in the House Mouse

 

208

 TABLE 15.2

 

Estimated Average Mutation Rates per Lethal-Producing Locus in Several Drosophila Species (After Dobzhansky, Spassky, and Spassky, 1952)

 

209

 TABLE 15.3

 

Frequency of Occurrence of Nine Different Dominant or Sex-Linked Mutations in Man

 

210

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
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Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

LIST OF FIGURES

Chapter II

 FIGURE 2.1

 

English Translation of the Japanese-Language Genetics “Short Form”

 

6

 FIGURE 2.2

 

English Translation of the Japanese-Language Pamphlet Distributed at the Time of Pregnancy Registration

 

8

 FIGURE 2.3

 

The Genetics “Long Form”

 

10

 FIGURE 2.4

 

The Form Used for Recording Pediatric Information at Age 9 Months

 

16

Chapter III

 FIGURE 3.1

 

The Topography of the Hiroshima City Region

 

30

 FIGURE 3.2

 

The Topography of the Nagasaki City Region

 

31

Chapter IV

 FIGURE 4.1

 

Symptom Ratio in Relation to Distance from Hypocenter for Hiroshima (Husbands and Wives Combined)

 

42

 FIGURE 4.2

 

Symptom Ratio in Relation to Distance from Hypocenter for Nagasaki (Husbands and Wives Combined)

 

43

 FIGURE 4.3

 

Total Dosage of Initial Gamma Radiation as a Function of Distance from the Hypocenter of the Explosion of a “Nominal” Atomic Bomb, from “The Effects of Atomic Weapons”

 

46

 FIGURE 4.4

 

Fast and Slow Neutrons Delivered per Square Centimeter as a Function of Distance from the Hypocenter of the Explosion of a “Nominal” Atomic Bomb, from “The Effects of Atomic Weapons”

 

46

 FIGURE 4.5

 

Neutron and Gamma Radiation Distance-Dosage Curves for the Atomic Bomb Explosions at Hiroshima and Nagasaki

 

51

Chapter VI

 FIGURE 6.1

 

A Schematic Representation of the Method of Sorting the Data to Obtain Non-Overlapping Indicators

 

73

Chapter VII

 FIGURE 7.1

 

The Distribution of the Frequency of Male Births by Age of Mother at the Birth of the Infant with Parity Ignored

 

89

 FIGURE 7.2

 

The Distribution of the Frequency of Male Births by Parity with Maternal Age Ignored

 

89

Chapter VIII

 FIGURE 8.1

 

The Distribution of the Frequency of Infants with Major Malformation by Maternal Age for Specified Parities

 

107

 FIGURE 8.2

 

The Distribution of the Frequency of Grossly Malformed Infants by Parity for Specified Maternal Ages

 

108

Chapter IX

 FIGURE 9.1

 

The Distribution of the Frequency of Stillborn Infants by Age of Mother for Specified Parities

 

123

 FIGURE 9.2

 

The Distribution of the Frequency of Stillborn Infants by Parity for Specified Maternal Ages

 

124

Chapter X

 FIGURE 10.1

 

The Distribution of Mean Birthweight in Decagrams by Parity for All Maternal Ages, and for Maternal Age 30 Only

 

133

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

 FIGURE 10.2

 

The Distribution of Mean Birthweight in Decagrams by Maternal Age for Fixed Parities (Parities 1 and 4)

 

133

Chapter XI

 FIGURE 11.1

 

The Distribution of the Frequency of Neonatal Deaths by Age of Mother for Specified Parities

 

152

 FIGURE 11.2

 

The Distribution of the Frequency of Neonatal Deaths by Parity for Specified Maternal Ages

 

153

Chapter XIII

 FIGURE 13.1

 

The Distribution of the Frequency of Autopsied Infants with Major Malformation, Relative to All Autopsied Infants, by Age of Mother with Parity Ignored

 

185

Chapter XIV

 FIGURE 14.1

 

A Graphical Representation of the Effect of Parental Exposure on: (1) the Sex Ratio; (2) the Frequencies of Malformed Infants, Stillborn Infants, and Infants Dying in the Neonatal Period; (3) Birthweight Means; and (4) Birthweight Variances

 

193

 FIGURE 14.2

 

A Graphical Representation of the Effect of Parental Exposure on: (1) the Frequency of Malformed Infants Alive at Age Nine Months; (2) the Frequency of Death in the First Nine Months of Life; and (3) the Anthropometric Measurements of Weight, Height, Head Circumference and Chest Circumference

 

194

 FIGURE 14.3

 

The Adequacy of the Data with Regard to Sex Ratio as Indicated by the Operating Characteristic (OC) Curves for Analyses Based on Sample Sizes of 5,629 Mothers and 2,453 Fathers, Where the True Proportion of Successes is Assumed to be 0.5198, the Value Observed in the Control Population

 

198

 FIGURE 14.4

 

The Adequacy of the Data with Regard to Malformations, Stillbirths, and Neonatal Deaths as Indicated by the Operating Characteristic (OC) Curves for Analyses Based on Samples of Size 1,097 Parents, Where the True Proportion of Successes are Assumed to be 0.0090 for Malformations and 0.0142 for Stillbirths and Neonatal Deaths, the Control Values

 

199

Chapter XV

 FIGURE 15.1

 

A Schematic Representation of Two Different “Mutation Spectra” with Reference to Degree of Viability, Both Compatible with the Existing Data

 

207

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Chapter I

BACKGROUND

THE present monograph is designed as a detailed report on certain efforts made during the period 1946–1955 to provide answers to the following two questions:

  1. Can there be observed, during the first year of life, any differences between the children born to parents, one or both of whom were exposed to the effects of the atomic bombings of Hiroshima and Nagasaki, and the children born to suitable control parents, and

  2. If differences do exist, how are these to be interpreted?

1.1 The general administrative framework of the study.—The study to be described was undertaken as one facet of a comprehensive attempt to obtain detailed information concerning the various possible late or delayed biological effects of exposure to an atomic bombing. Certain information pertinent to the development of the over-all program is essential to an understanding of the manner in which the effort to provide answers to the two questions listed above evolved.

The background of this program begins shortly after Japan's surrender, when a Joint Army-Navy Commission made extensive observations in Hiroshima and Nagasaki on the survivors of the bombings. At the conclusion of the Commission's work its chairman, Col. A.W. Oughterson, M.C., AUS, recommended to the Surgeon General of the Army that the National Academy of Sciences—National Research Council be requested to undertake a long-range study of the medical and biological effects of the atomic bomb. This recommendation was transmitted by Surgeon Gen. Norman T.Kirk to Lewis H.Weed, chairman of the Division of Medical Sciences of the National Research Council. As a result, in June of 1946, a conference group was convened by the Council, and in November, following its recommendation, a five-man commission composed of representatives of the Council, the Army, and the Navy left for Japan for the purposes of (1) determining the current status of Japanese work on atomic bomb casualties, (2) evaluating the feasibility of American participation in continued research on these casualties, and (3) indicating the lines along which such studies should proceed. This commission, composed of Austin Brues, Paul S.Henshaw, Lt. Melvin Block, M.C., AUS, Lt. James V.Neel, M.C., AUS, and Lt. (j.g.) Frederick Ullrich, (MC) USNR, submitted a report of its findings to the Council in January, 1947.

The June, 1946 conference group had recommended that appropriate action be taken to obtain a Presidential Directive authorizing the National Research Council to initiate a long-range study of atomic bomb effects. This Directive was issued at the request of the Secretary of the Navy, James T.Forrestal, in November, 1946. and on its authority the Council, in January, 1947, established a Committee on Atomic Casualties, composed of Thomas M.Rivers (chairman), George W.Beadle, Detlev W. Bronk, Austin Brues, George M.Lyon, C.P. Rhoads, Shields Warren, Stafford L.Warren, George H.Whipple, and Raymond E.Zirkle.

At its first meeting, on March 25, 1947, the Committee on Atomic Casualties went on record to the effect that a large-scale program should be organized towards the end of learning as much as possible of medical significance from the Japanese experience. Financial support for the program was sought from the U.S. Atomic Energy Commission, which, during the fall of 1947, formally signified its intention of financing the program in Japan.

Ever since November of 1946, i.e., beginning with the visit of the five-man commission referred to earlier, there has been resident in Japan a group of investigators and supporting

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

personnel concerned with various phases of the over-all program. This group has been known as the Atomic Bomb Casualty Commission (ABCC). Starting with a scant handful, it grew until at its peak strength it consisted of 143 “allied” personnel (Americans, English, Australians, etc.) and 918 Japanese Nationals.

At the time that the ABCC began its operations in Japan, that country was of course under U.S. Military Occupation. It was Occupation policy that groups such as the Atomic Bomb Casualty Commission, having to do primarily with the Japanese people, should work with and through some existing Japanese agency. In early 1947, the Japanese Ministry of Welfare, at the instigation of the Public Health and Welfare Section of GHQ, SCAP, established a National Institute of Health, designed to occupy roughly the place in Japanese medicine which the National Institutes of Health then occupied in the United States. Several months later, in June of 1947, Brig. Gen. C.F.Sams, then Chief of the Public Health and Welfare Section, suggested that it would be appropriate for the ABCC to develop its program in cooperation with the Japanese National Institute of Health. Eventually there was established an Atomic Bomb Casualty Section of the Japanese National Institute of Health. The personnel of this Section have been closely integrated with ABCC personnel, in such a manner as to make the program truly a combined Japanese-American effort.

1.2 The beginnings of the Genetics Program. —So well known are the genetic effects of the irradiation of a variety of plant and animal material that inevitably one of the foremost questions in the minds of those considering the possible late consequences of the atomic bombings had to do with the characteristics of the children of exposed parents. As a member of the five-man survey commission which went to Japan in the late fall of 1946, the senior author was especially responsible for an evaluation of the lines along which the study of this question could best proceed. The results of this evaluation were laid before an ad hoc Genetics Conference convened by the National Research Council in the summer of 1947, composed of G.W.Beadle (chairman), D.R.Charles, C.H. Danforth, H.J.Muller, L.H.Snyder, and Lt. J.V.Neel. It was clearly recognized by the members of this Conference that the demonstration of the potential genetic effects of the irradiation of the human species presented many difficulties not encountered in laboratory material. It was further recognized that post-war conditions in Japan were by no means the most favorable for a study of this type.

In finally recommending that a rather large-scale effort be undertaken in Japan, the Conference felt constrained to make the following statement:

“Although there is every reason to infer that genetic effects can be produced and have been produced in man by atomic radiation, nevertheless the conference wishes to make it clear that it cannot guarantee significant results from this or any other study on the Japanese material. In contrast to laboratory data, this material is too much influenced by extraneous variables and too little adapted to disclosing genetic effects. In spite of these facts, the conference feels that this unique possibility for demonstrating genetic effects caused by atomic radiation should not be lost.” (Genetics Conference, 1947.)

Although the study which was undertaken will for purposes of convenience be termed the “Genetics Program,” because of its obvious implications, it must be emphasized that those concerned in its organization and conduct have always regarded it first and foremost as an effort to collect data on the characteristics of the children born to the irradiated survivors of the atomic bombings, data which, if indicating that the bombs had had some effect, were then subject to several possible interpretations, genetic and otherwise.

1.3 The early Japanese efforts along these lines.—The U.S. Army-Navy Joint Commission which studied the medical effects of the atomic bombs in Japan as soon as possible after the surrender worked in close cooperation with the Medical Section of a special Committee for the Investigation of the Effects of the Atomic Bombs, appointed by the Japanese National Research Council. The members of this group also recognized clearly the desirability of long-range studies on the medical effects of the bombs, but in the organization of such studies were greatly handicapped by post-war conditions in Japan. The administrative reorganization of the Japanese National Research Council and other aspects of Japanese science which the Occupation sponsored also unavoidably created uncertainties which delayed the work of this group.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Despite these many difficulties, at the time that the U.S. National Research Council's survey group visited Hiroshima in December of 1946 they found the Japanese planning to obtain data on the characteristics of the children then being born. This program, under the immediate supervision of Dr. I.Matsubayashi, was carefully reviewed. It was felt to be inadequate in several respects. Nevertheless, it is certainly a favorable commentary on Japanese interest in the problem and desire to carry on research that plans for even a small program had been set up under the circumstances then prevailing. This program was in effect very briefly and then merged with the program of the ABCC; Dr. Matsubayashi became a member of the ABCC staff.

1.4 Scientific and administrative considerations shaping the nature of the program in Japan.—The lines along which the Genetics Program in Japan was laid out in 1946–1947 were dictated not only by purely scientific considerations but also by certain practicalities of the situation. The more important scientific considerations were as follows:

1.4.1 The possible observable genetic effects of irradiation upon the first generation born after an atomic bombing are many and varied. These include changes in the sex ratio, an increase in the frequency of stillbirths, an increase in the frequency of congenital malformation, an increase in infant mortality, etc. Each of these possible indicators of genetic damage is also influenced by a number of other factors; there are no known unique yardsticks of genetic damage. Under these circumstances, the crux of any program of study was the feasibility of establishing control material which insofar as possible differed from the irradiated only with respect to the radiation factor.

1.4.2 At the time this program was organized, although there was available a mass of data concerned with spontaneous mutation rates and the genetic effects of irradiation on Drosophila, little was known concerning spontaneous mutation rates in mammals, including man, and, with the exception of the work of Charles (1950), still less concerning the mutagenic effects of the irradiation of mammalian material. Largely by extrapolation from the Drosophila material, it could be anticipated that in the light of the probable irradiation dosages sustained by the survivors of Hiroshima and Nagasaki, only very slight genetic effects should be detected in the first generation. In particular, it is worth pointing out that although the atomic bombs were dropped in August of 1945, because of the various time-consuming administrative developments recounted above, involving policy decisions and their means of implementation for the National Research Council, the U.S. Atomic Energy Commission, the U.S. Army of Occupation in Japan, and the Japanese Government, it was March of 1948 before the Genetics Program as it will be described presently was actually in action. The first children to come under the scrutiny of the program were conceived in October of 1947. There was thus a loss of information for the two years following the bombing. For a variety of reasons, some to be discussed below, it was felt that no attempt to reconstruct the frequency of malformations, stillbirths, or neonatal death during these first two post-bomb years could succeed. The practical corollary of these considerations was the necessity, once the program got under way, of a large-scale effort which would utilize as much of the available material as possible.

1.4.3 It was apparent from the outset that the Genetics Program could not and would not operate independently of the various other facets of the activities of the ABCC, but as one of a collection of integrated units. However, the organization of the Genetics Program proceeded somewhat more rapidly than the organization of other segments of the ABCC. Furthermore, there was for some time uncertainty as to the scale of operations in Japan. Under these circumstances, it was necessary to design a program with a basic, irreducible framework to which additions could be made later if circumstances permitted, but the additions had to be of such a nature that they would not invalidate a comparison of the early and later data. It was further necessary that the observations selected as possible indicators of genetic damage be relatively simple, as devoid as possible of the subjective element, and capable of being carried out under the conditions in Japan to be described below.

1.5 Local considerations shaping the nature of the program in Japan.— Among the conditions in Japan which were determining elements in the program, the following deserve special mention:

1.5.1 In Japan, the practice of obstetrics

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

is still largely in the hands of midwives. They attend approximately 96 per cent of the deliveries. Thus, in 1948, out of a total of 2,681,624 deliveries in Japan, 2,468,821 were attended by midwives, 102,627, by physicians, and 110,176 by unlicensed attendants. The deliveries for which midwives and unlicensed attendants are responsible usually occur at home.

The prerequisites for licensure as a midwife were revised upwards during the Occupation. However, the great majority of midwives now in practice were of course licensed under the previous system. This required that a candidate for admission to a school of midwifery had completed a kotoshogakko education (about eight years, corresponding to grammar school). Although not required, some candidates had also completed chugaku (middle school, about four years, corresponding to high school). The course in midwifery covered two years. One could either spend all two years in a school, or spend one year in school and the last year obtaining experience either in the obstetricsgynecology department of a hospital or in association with a senior midwife. One had then to pass a prefectural examination for licensure. The legal minimum age was 20 years. Not uncommonly a licensed midwife married soon after completing school and did not return to the practice of midwifery for some years.

It is apparent that whatever the midwife's qualifications for the practice of obstetrics may be, her training had not prepared her for the detection and careful description of congenital malformations. This made it necessary with respect to the Genetics Program to develop a system whereby each newborn infant was seen by a physician as soon as possible after birth.

1.5.2 The Japanese economy during the immediate post-war years, when this study was instituted, was marginal. There was strict rationing of food and articles of clothing. Since official rations were inadequate to meet caloric needs, there was a widespread “black market” in food. One of the features of the ration system was special provision for pregnant women. Such women (or their designated representative) upon certification of pregnancy by a midwife or physician could register at any time after the fifth lunar month of pregnancy and thereby obtain access to certain items of value to them and their future children. Registration was revealed by a preliminary study to be in excess of 95 per cent complete. There was thus available a system whereby very nearly all pregnant women could be contacted at mid-pregnancy.

1.5.3 Finally, mention must be made of the psychological and sociological pitfalls involved in a study of this type. This is scarcely the place for a detailed analysis of the psychological problems inherent in the operations of the ABCC in Hiroshima and Nagasaki. Some of the inevitable problems in Japanese-American relationships are apparent. Others were unexpected (Matsumoto, 1954). Each step in the program had to be planned and taken cautiously, after every effort had been made to explore the possible repercussions. In retrospect, the first year of activity in Japan may be characterized as an apparently interminable series of conferences punctuated by weekly crises which, although often inconsequential in retrospect, at the time threatened to stall the entire operation until met. Lacking any semblance of authority in Japan, the ABCC was wholly dependent upon the voluntary cooperation of the Japanese people. The good will of the city officials, local physicians, and—above all—of the midwives, was, if not indispensable, highly desirable. It should particularly be mentioned that in Japan the social stigma attached to the birth of a malformed child is rather considerable. Every effort had to be made to develop a program which would not antagonize the mothers of malformed children by exposing them to what they considered undue publicity. In this effort, the mid-wives were the key.

Although the destruction and desolation which were the aftermath of the atomic bombings have been many times described, neither photographs nor words are adequate to the occasion. In addition to the post-war stresses and strains to which all the inhabitants of Japan were subject, the citizens of Hiroshima and Nagasaki were confronted with a more formidable job of reconstruction than the inhabitants of most Japanese cities, badly bombed though these had been. These are not the circumstances in which research or even cooperation in the research of others flourishes.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Chapter II

THE PLAN

WITH the considerations outlined in Chapter I in mind, a plan of attack on the problem was developed which will now be described.

2.1 Pregnancy registration.—As mentioned earlier, in the post-war years the ration system in Japan was such that pregnant women upon registration of their pregnancy following the completion of the fifth month of gestation could thereby acquire access to certain rationed items. With the cooperation of the city administrators of Hiroshima, Nagasaki, and Kure (a control city), a system was instituted whereby at the time of her registration at the city hall (or district office) for ration purposes, each pregnant woman or her representative in these three cities completed the first two-thirds of a questionnaire which included such items as identifying information, a brief radiation history of the husband and wife, a short summary of the past reproductive performance, and pertinent details concerning the present pregnancy. In the majority of instances the informant for this questionnaire was the pregnant woman herself. Only rarely were both parents available. Accordingly the radiation information on this questionnaire tended to be more reliable for the wife than the husband (cf. Sec. 4.6).

Figure 2.1 is an English translation of this questionnaire, which will be referred to as the “Genetics Short Form.” This questionnaire was administered by trained clerks who occupied a special office in the city hall (or district office). The actual collection ‘of data began in Hiroshima in February, 1948; in Kure in March, 1948; and in Nagasaki in July, 1948. The questionnaire was filled out in duplicate; the original was then given the registrant, while the Commission retained the copy. At the time of termination of the pregnancy, the midwife or physician in attendance completed the questionnaire by answering certain questions pertaining to the characteristics of the child and delivery. More specifically, information was requested on the following possible indicators of a genetic difference between the children of control and irradiated parents: sex, birthweight, stillbirth, and presence of malformation. In case there was an abnormal termination (e.g., stillbirth, malformation), the midwife informed the Commission by telephone as soon as possible. If the outcome appeared normal, the questionnaire was held by the midwife until collected by a Commission clerk. Such collections were at first at weekly and later twice weekly intervals. Regardless of the type of termination, a Japanese physician in the employ of the Commission or the Japanese National Institute of Health called to examine the child—at once, if there was a report of an abnormal termination, or on a somewhat more leisurely schedule if the termination was reported as normal. Midwives received a small fee for each questionnaire they completed. Because of this lag between birth, questionnaire collection, and examination by a physician, it was also possible to obtain rather complete information concerning death during the first 7 days post partum, hereafter referred to as neonatal death.

The cooperation both of the mother and of the midwife in this study was of course entirely voluntary. An attempt was made at the time of pregnancy registration to explain the rudiments of the program to the registrants, and, in addition, each mother was given a brief printed description of the program. Figure 2.2 is a translation of this description. Numerous meetings were held with the Midwives' Associations of the cities to explain the program and answer questions. Attendance at the meetings was usually excellent, although, the Japanese birth rate being what it was, apt to diminish appreciably between the opening and closing of any given meeting.

Approximately a year and a half after the

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

FIGURE 2.1—English translation of the Japanese-language “Genetics Short Form.”

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

program went into operation, an attempt was made to ascertain what proportion of births in Hiroshima were to mothers registered in the Genetics Program, i.e., to determine the completeness of our pregnancy registration. Inasmuch as studies by the Public Health and Welfare Section, GHQ, SCAP (Mr. L.V.Phelps) had revealed that the official Japanese registration of births by place of occurrence during the period of this study was quite complete,1 it was felt that the most valid (as well as convenient) approach to this evaluation would be to compare the number of terminations recorded by the Genetics Program each month with the number officially registered in the city. The comparison follows:

1948

City

ABCC

%

August

713

653

91.6

September

723

674

93.2

October

602

614

102.0

November

625

596

95.4

December

555

577

104.0

1949

 

January

1,001

914

91.3

February

759

703

92.6

March

740

675

91.2

April

719

630

87.6

May

707

634

89.7

June

728

711

97.7

July

826

759

91.9

August

762

703

92.3

September

740

685

92.6

 

10,200

9,528

93.4

Percentages greater than 100 are probably best explained by changing city boundaries and monthly carry-overs, especially in the case of the December, 1948 figure, because of the Japanese custom of delaying registration on a child born in late December. Assuming that terminations known to the ABCC were also known to the city, this indicates that approximately 7 per cent of the births occurring in the city were to mothers not registered with the Genetics Program.

A large proportion of these births to parents not registered with the Genetics Program of the ABCC subsequently came to the attention of the Program in the following two ways: (1) At the time of registration of the birth with the city, the city clerks routinely inquired if the pregnancy was known to the ABCC, and if not, directed the registrant to the Genetics Program offices in the city hall. (2) Private doctors and midwives frequently reported the names of all women whom they attended who were not registered with the Genetics Program. Births coming to the attention of the Program through these channels were placed in an “Unregistered Series.” From time to time, in an effort to improve the coverage of the Program, the reasons were investigated for the failure of the pregnancies resulting in these births to be included in the routine registration. One of the more complete investigations of this type was carried out in Hiroshima in October of 1952 and dealt with 147 unregistered births occurring in the period of June through September of that year. The reasons for not registering given by the mothers of these 147 children were as follows:

 

Reason for failing to register

No.

1.

Arrived in city just prior to birth of child

20

2.

Registered pregnancy at city hall, but failed to visit ABCC office there

37

3.

Failed to register either with city for ration purposes or with ABCC, although in town during pregnancy:

 
 

Too busy

23

 

Forgot

19

1  

The actual figures for registration of live births during the years 1948, 1949, and 1950 are 98.1%, 98.8%, and 98.9% respectively, while for stillbirths the corresponding figures were 98.7%, 99.4%, and 99.4% (cf. Public Health & Welfare in Japan, 1948, 1949, 1950, by Public Health & Welfare Section, GHQ, SCAP).

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
 

First seen by midwife late in pregnancy; felt registration wasn't worth bothering with

5

 

Requested someone else to register; that person failed to do so

17

 

Too sick to register

4

 

Didn't know about registration

12

4.

Miscellaneous causes

10

 

147

TRANSLATION OF PAMPHLET DISTRIBUTED AT THE TIME OF PREGNANCY REGISTRATION

To All Prospective Mothers:

The ABCC has a request to make of all prospective mothers. I presume you are familiar with the research project of the ABCC. The American and Japanese doctors work together in giving physical examinations to all babies born in Hiroshima, Kure, and Nagasaki, and cooperate in carrying on other scientific researches. We hope that those who have encountered the bomb and also those who have not will respond to our program. A comparative study of the physical conditions of the persons who experienced the bomb and persons who did not, insures the scientific accuracy of our studies.

When you register your pregnancy at the city office will you kindly fill out a questionnaire for ABCC? Our representative will ask you questions and fill out the questionnaire. You need not be worried about the questionnaire for it contains only questions concerning your expected baby, name of parents, birthdates, date of marriage and history of exposure to the atomic bomb. If you have any questions to ask, our representative will be happy to assist you. The form, on a white sheet, which you will be asked to take home with you, will be filled out by your attending midwife or doctor and returned to ABCC.

Within a month after delivery an ABCC doctor will call on you and make a physical examination of your baby. (If unfortunately your pregnancy terminates in abortion, stillbirth, or any other abnormality, an ABCC doctor will also call on you.) By this examination you will be able to know your baby's true physical condition and at the same time you will be making an important contribution to medical science.

In the ABCC clinic the most modern X-ray and other medical equipment are available if the necessity of a thorough examination of your baby is found necessary. In such cases the ABCC will call for you and bring you and your baby to the clinic. The results of the examinations are strictly confidential but if you desire they may be available to your family doctor. All services are performed free of charge.

NOTE:

1. Regardless of whether or not you experienced the atomic bomb, whether your pregnancy terminates in abortion or stillbirth, your cooperation will be appreciated.

2. Please preserve the questionnaire that you were asked to take home and have the attending midwife or doctor fill it out after delivery. If you lose the questionnaire it will be issued to you again, if you will present your Expectant Mother's Notebook at the city office.

3. Please inform the ABCC if you change address at any time.

Your kind cooperation is requested in this medical research program.

FIGURE 2.2—English translation of the Japanese-language pamphlet distributed at the time of pregnancy registration.

Reason (1) appears to represent an unavoidable loophole in the program, but inasmuch as mothers falling into this category as a rule were unexposed, this does not represent a serious loss of data. Reason (3) also represents an unavoidable loophole in a program geared as this was to a civic function. Reason (2), on the other hand, represented an unnecessary loss of data (which could be and was rectified), due for the most part to the fact that the city clerk failed to direct the registrant to the ABCC office, either through forgetfulness or, in the case of new clerks, not knowing that this should be done. Because of differences in city administration practices, the percentage of unregistered births was always less in Nagasaki than in Hiroshima.

The question naturally arose as to whether the information collected concerning registered births should also be obtained for these unregistered births, following which the two sets of data would, for analytical purposes, be combined. In view of the extent to which recent arrivals to the city enter into the composition of the unregistered group (20/147 in the preceding analysis), it was felt that it would be better not to combine the two series, even though this involved the loss of a certain amount of badly needed data.

As mentioned earlier, it was not necessary that the pregnant woman register in person, it being possible for her designated representative to register for her. In approximately 4 per cent of all registrations, neither the prospective mother nor the father appeared at the city hall,

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

the registration being carried out by some third party. Such individuals of course were unable to answer many of the items on the questionnaire. In these instances, a clerk was sent to the home to obtain the necessary data.

2.2 Special studies on abnormal terminations. —In the event that a pregnancy terminated abnormally, as in a stillbirth or a child with a congenital malformation, a supplementary questionnaire was completed in the patient's home by a doctor in the employ of the ABCC. This questionnaire covered in some detail gynecologic history, maternal disease during pregnancy, past reproductive performance, and economic status. The actual questionnaire is reproduced in Figure 2.3 and will be referred to as the “Genetics Long Form.” In addition, in the case of abnormal terminations, blood was obtained from the mother for a serological test for the presence of syphilis.

If the physician charged with completing the supplemental questionnaire encountered an unusual abnormality, or one concerning whose nature he was unsure, he could, if the parents were willing, arrange for the child to be seen by an American-national pediatrician at the ABCC headquarters, for such diagnostic studies as seemed necessary, as well as photographic documentation of the case.

The Japanese physicians concerned with the home examination of these infants were for the most part recent medical school graduates. Many of them were employed on a half-time basis, the remainder of their time being devoted to hospital duties. Each of these men, before he was sent out on home calls, received instruction in the systematic examination of the newborn infant. In addition, from time to time lectures were given on the recognition of the more common congenital abnormalities. Between 30 and 40 full or part-time physicians were employed in this capacity at any one time. For a variety of reasons, personnel turn-over was at first relatively high; this necessitated a constant training program.

2.3 The “10-percent sample.”—Each woman as she registered received a registration number for her pregnancy, these being assigned in sequence and without respect to radiation history. For every tenth registration, which is to say, all registrations for which the terminal digit in the registration number was zero, the same supplemental questionnaire just described in connection with abnormal terminations was completed in the home. A serological test for syphilis was also carried out on the mother of every tenth termination. In this way a 10 per cent sample was obtained with which to supplement the information obtained on the original questionnaire concerning the comparability of control and irradiated parents. In addition, information was obtained of value in analyzing the causation of abnormal pregnancy terminations.

2.4 The accuracy and reproducibility of the anamnestic data obtained on the Genetics Short Form and the Genetics Long Form.—The information accumulated in the course of this study is of two types: anamnestic, and observational. The accuracy of both types of information was of course a matter of vital concern. During the period covered by this investigation, many women in the study cities had several pregnancies. Each pregnancy of a given woman was registered independently of any others. Discrepancies in the answers to particular questions in the course of multiple registrations by a given woman provide some insight into the reliability of the material. In addition, because of overlaps in the various segments of the ABCC program, the same information might be obtained independently in different studies.

The information obtained on the Genetics Short Form is of three main types: (1) radiation history, (2) history of past reproductive performance, and (3) observations by midwives and physicians on the outcome of the current pregnancy. The reliability of information of types (1) and (3) will be examined in detail in Chapters IV, VIII, IX, and X. The attempt to obtain information of type (2) was motivated by the possibility of detecting an increase in the proportion of abortions and miscarriages among conceptions occurring in the period immediately following the bombing. However, a preliminary analysis of repeat registrations by the same mother, in May of 1951, suggested that the error in the reporting of abortions and miscarriages was such that any attempt to utilize these data would be ill-advised. This study thus utilizes only direct observations collected under supervision during the years 1948– 1954,

The material sought on the Genetics Long Form was collected with three purposes in mind: (1) the description in some detail of congenital defect, (2) the recording of certain

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

SPECIAL BIRTH QUESTIONNAIRE

FIGURE 2.3—The Genetics “Long Form.” Explanation in text.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

supplementary technical observations of possible pertinency to pregnancy outcome such as economic status and maternal luetic infection (as revealed by serological testing), and (3) the recording of considerable background information of possible relevancy to the manner in which a given pregnancy terminated, with particular reference to the problem of congenital defect. This included a brief family history of both father and mother, a detailed reproductive history of the mother, disease during pregnancy, etc. The reliability of the material collected under headings (1) and (2) will be discussed in Chapters V and VIII. The reliability of anamnestic data mentioned under heading (3) will be briefly considered here. This material is in the strict sense not relevant to the problem of radiation effects, the questions having been introduced because of the opportunity of adding to existing knowledge concerning the etiology of congenital defect. Unfortunately, particularly with reference to the occurrence of congenital defect in other members of the family, several analyses have raised serious doubts as to whether these histories are of sufficient reliability for research purposes. There is in general less major congenital defect reported in family histories than would be expected on the basis of the observations made during the course of this investigation. This may in part be due to lack of information and forgetfulness, but is probably in no small measure due to the social stigma connected with congenital defect, and the consequent efforts to conceal it.

2.5 The autopsy program.—As the over-all program of the ABCC developed, and particularly after a Department of Pathology was established, it became possible to initiate the performance of autopsies on deceased or stillborn infants falling within the scope of the program. Because of the greater concentration of Commission personnel in Hiroshima than in Nagasaki, infant autopsies were begun in Hiroshima in December, 1948, but not in a methodical fashion in Nagasaki until several years later.

A request to perform an autopsy was routinely made of the parents of each stillborn infant and of each infant dying during the neonatal period coming to the attention of the Commission. If permission was granted, the contactor brought the cadaver to the ABCC pathology laboratory. A complete autopsy was performed in all cases save where maceration made this impossible. Photographs and X-rays were taken when indicated. A copy of each autopsy protocol was ultimately filed with the appropriate Genetics Long Form. The cadaver was then carried to a crematorium in an ABCC vehicle. Ashes were returned to the family in a suitable receptacle on request. Cost of the coffin and cremation fee were borne by the ABCC.

When the autopsy program was well under way in the two cities, some 50 per cent of the total available material came to autopsy. For instance, an analysis of 300 consecutive registrations terminating in stillbirths or neonatal deaths, beginning January, 1950 in Hiroshima, revealed that out of the total of 311 infants involved, 158 (50.8%) came to autopsy. Of the remaining 153, 46 (14.8%) were seen by an ABCC physician but did not come to autopsy. There were 107 (34.4%) who were not seen by an ABCC physician, and concerning whose appearance at birth there is only the statement of the mother and attending midwife. This represents the most serious potential loss of information in the entire program, since a certain amount of congenital malformation could well go unrecognized or concealed. However, these unexamined infants can introduce bias into the findings only if there is a difference in reporting on the part of exposed and unexposed parents. We shall examine the latter possibility in Chapter XIII.

2.6 The collection of data on infants aged 9 months.—Japanese homes are not always well lighted and, because of their construction and the fuel shortage, are decidedly cold in winter. These conditions are not favorable for an adequate physical examination of a newborn child. The possibility had to be recognized that for these reasons, as well as diagnostic oversights, some malformations were not being observed at birth. Furthermore, certain defects, such as congenital dislocation of the hip, spastic paraplegia, deafness, blindness, congenital heart disease, or mental defect are not always readily diagnosable at birth. Accordingly, in January of 1950, the earliest date at which the over-all development of the ABCC permitted such action, a program was inaugurated to bring into the central clinical facility at age 9 months as many of the children examined shortly after birth as possible, both as a check on diagnostic

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

oversights at the time of the first examination and on supplementary diagnoses. Certain anthropometric measurements were also obtained as an index of general physical development. Furthermore, because of the possible relationship between genetic damage and death during the neonatal period of infancy, information as to time and manner of death was obtained for deceased children. The age for this study was set at 9 months rather than, e.g., one year, because of the relative ease with which a 9-month-old infant may be examined. The form on which the data were recorded is reproduced as Figure 2.4, and will be referred to as the Genetics 9-Months Follow-up.

Since it was not possible to conduct studies of all the babies examined at birth who were still alive 9 months later, a system of obtaining a random sample had to be set up. This was done by the simple expedient of calling in babies for examination according to the terminal registration digit of the pregnancy. Each month all babies with certain specified terminal registration digits were seen, the number of children seen being regulated by the other demands on the clinical facility and the personnel available. In this fashion, a random 10, 20, 30, etc. per cent of the original group could be called in for examination. Parental cooperation was usually excellent. Where a child who was included in the sample could not be examined, an attempt was made to establish why, in an effort to detect possible sources of bias.

A comparison of the recorded findings on a series of infants examined shortly after birth and again at 9 months provides a check on both the clerical and medical efficiency of the program. Such a comparison was carried out in 1952, based on 4,578 pregnancy terminations studied at birth and followed up again at age 9 months in Hiroshima in 1951. The comparison involved the findings coded on the IBM cards used for the final analysis (see below) rather than on a matching of the two original forms, since the IBM cards are of course the basis for the final tabulations. Particular attention was directed towards the occurrence of gross malformation in the two series.

A total of 38 clerical errors came to light. Approximately half of these arose in the following manner: a tentative diagnosis of major malformation made when a child was seen in the home was not confirmed when the child was brought into the central facility for examination a short time thereafter. When this same child was seen at age 9 months and the defect again not observed, this was erroneously coded as a refutation of an earlier diagnosis, when in fact no actual diagnosis had been reached. This error did not affect the actual analysis of the data. The other 20 clerical errors were of a more serious nature, involving for the most part an error in the use of the 6-digit code developed in connection with this study for the classification of congenital malformation.

From the medical standpoint, the comparison of the two sets of records brought out the unreliability, under the conditions of this study, of the diagnosis shortly after birth of congenital heart disease and congenital torticollis. This finding led to omitting these two diagnoses from the “at birth” data, although both were included in the “9 months” data.2 Excluding these two diagnoses, there were 48 instances of major defect listed among the 4,578 terminations studied shortly after birth. The follow-up examination at age 9 months increased the number of diagnosed major defects (exclusive of congenital heart disease) to 122. On the face of it, this amounts to a 154 per cent increase. However, analysis of the data revealed that three diagnoses contributed disproportionately to the 9-months total, as follows:

Diagnosis

No. of times made on first examination

No. of times made on second examination

Dysplasia of acetabulum

3

26

Pilonidal sinus

5

22

Inguinal hernia (females only)

5

19

 

13

67

Exclusive of these three diagnoses, there were 35 diagnoses of major defect at the time of the first examination (all confirmed later), as contrasted to 55 at the second examination, an increase of 57 per cent. It was apparent from this that the 9-months examination not only served as a valuable check on the “at birth” program but significantly increased the amount of congenital disease recognized in these children, although the bulk of this contribution was due

2  

The diagnosis of congenital heart disease was based on one or more of the following criteria: persistent cyanosis, a grade III or IV apical systolic murmur, a precordial thrill, or cardiomegaly in the absence of another adequate explanation.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

FIGURE 2.4—The form used for recording pediatric information at age 9 months. Explanation in text.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

to a relatively few diagnoses. The question of whether these three common diagnoses “unbalance” the 9-months data will be examined later. On the basis of these findings, the decision was made to conduct separate analyses on the malformation findings “at birth” and the additional findings at the later examination. It should perhaps be emphasized at this point that although we have presented the above analysis in terms of specific defects, the unit in the statistical analysis to be presented later of the relationship between radiation history and congenital defect was the malformed child rather than specific defects, i.e., for analytic purposes each child is scored only once regardless of the number of major defects present.

2.7 The processing of the data.—All of the questionnaires employed in this study were checked for completeness by trained clerks. In the event of an omission or an obvious error, the individual concerned was queried either by mail or by a “contactor.” Where a discrepancy appeared between the information obtained on a first registration and on a subsequent registration by the same couple, an attempt was made to determine which of the two statements was correct and the reason for the discrepancy. When the questionnaires were completed, the data necessary to the projected analyses were coded, and the coded results transferred to standard 80-column machine tabulation cards. The codes used for the Genetics Short Form, the Genetics Long Form, and the Genetics 9-Months Follow-up are reproduced in Appendix 1.

2.8 The study of spontaneous abortions.— Early in the planning of the study, the possibility presented itself that a significant fraction of the detectable genetic effects of the atomic bombs on the first post-bomb generation would be in the form of dominant lethals which would find expression during the early stages of pregnancy. Although some of these dominant lethals might manifest themselves prior to implantation, others might not be effective until a month or two after implantation. Theoretically, the occurrence of dominant lethals in any number might be detectable through an increase in early spontaneous abortions.

In the fall of 1949 an attempt was initiated in Hiroshima to obtain as many records as possible of pregnancies terminating spontaneously prior to the twentieth week of gestation. Data were collected through the personal contact of one physician with the practicing obstetricians and gynecologists of the city. Radiation histories were obtained on each couple involved, with the intent of determining whether these histories differed significantly from those obtained from parents when the pregnancy was of twenty or more weeks' duration.

In the fall of 1950, the physician originally responsible for the collection of these data severed his association with the ABCC; the collection of the data was continued by two younger men. The collection of data was discontinued in early 1952. Data on 1,053 early spontaneous terminations were obtained during the first portion of this study, and information on 638 during the latter portion.

Many problems were anticipated in the collection of data on early spontaneous terminations; most of these anticipations were realized. During the spring of 1952, a preliminary analysis of these data was carried out. This analysis clearly revealed heterogeneity within the data, in terms of differences between the findings of the first and second portions of the program. Because of the impossibility of determining the source of these differences, as well as continuing difficulty in the collection of such data, this aspect of the program was abandoned, and will not be referred to again.

2.9 Cytogenetic effects of the atomic bombs. —As one facet of the over-all Genetics Program, the possibility has been explored of detecting by cytological methods chromosomal damage among the survivors of the bombings. Testicular material obtained either at the time of surgery, by biopsy, or at autopsy was examined, using appropriate methods. These studies, which will be described in detail elsewhere by Dr. M.Kodani, revealed an unsuspected amount of chromosomal polymorphism among normal Japanese, a finding which has served as a serious drawback in the use of this material as originally envisioned.

2.10 The decision to discontinue work in Kure.—At the outset of the study, when satisfactory information was not available concerning the composition in terms of irradiation experience of the population of the cities of Hiroshima and Nagasaki, an effort was made to collect control data in the city of Kure, located some 18 miles from Hiroshima. Preliminary analyses of the year-to-year data quickly revealed

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

that a considerable proportion of the inhabitants of the cities of Hiroshima and Nagasaki during the years 1948 through 1953 had not been there at the time of the atomic bomb explosions. Thus there existed in these two cities a source of internal controls which appeared to obviate the necessity for a separate control city. Accordingly, in September, 1950, after data had been collected on some 8,391 pregnancy terminations, work was discontinued in Kure.

2.11 The termination of the program In January, 1954.—At the time that the program which has just been described was initiated, Japanese birth rates were at record levels. However, in 1948 and 1949 the Japanese government, as one of a series of measures designed to reduce the disparity between population number and available food resources, liberalized the legal indications for the performance of “therapeutic” abortions by physicians. Although exact figures are impossible to obtain, in 1951 approximately 300 pregnancies were being interrupted each month in Hiroshima alone. In consequence of this and possibly other measures, the birth rate in Japan, including, of course, Hiroshima and Nagasaki, underwent one of the most spectacular declines ever recorded in a civilized country (Koya, 1953, 1954; Population Reference Bureau, 1953). The decline in actual number of births registered with the Genetics Program in the two study cities is shown in Table 2.1. In addition, during the first five years of the study, there was not only an absolute decline but in Hiroshima, the largest source of data, there was also a tendency toward a relative decrease in the numbers of infants born to more heavily irradiated parents. The reasons for this are not entirely clear. In part the finding is undoubtedly due to emigration from the city and completion of reproductive span on the part of older exposed individuals, without proportional replacement by younger age groups, but other factors may also be involved.

In the original planning of the program, the anticipated duration had been approximately ten years. By 1952 the annual decline in the amount of data becoming available had reached the point where it was apparent that a serious reconsideration of the duration of the program was indicated. Accordingly, on July 10–11, 1953, a Second Genetics Conference met to consider the results of a preliminary analysis of the data, and to reach recommendations concerning the future conduct of the work. The members of this conference were Dr. G.W. Beadle, Dr. D.R. Charles, Dr. C. C. Craig, Dr. L.H. Snyder, and Dr. Curt Stern (chairman) with Drs. W.J.Schull and J.V.Neel functioning ex officio. In view of the relatively small expected return, in terms of reducing the sampling variances of possible differences, from observations extending over an additional four years, and in the light of the very real problems and the expense involved in maintaining the program at a satisfactory level of efficiency, it was the unanimous recommendation of the Conference that the program be terminated in the near future. This recommendation was accepted by the Committee on Atomic Casualties; actual data collection was suspended in February of 1954.

TABLE 2.1 PER CENT OF ALL REGISTRATIONS (INCLUDING THOSE INVOLVING PARENTAL CONSANGUINITY) WITH AT LEAST ONE PARENT HEAVILY EXPOSED (RADIATION CATEGORIES 4, 5)

 

Nagasaki

Hiroshima

 

Year

M or F, 4 or 5

Total

%

M or F, 4 or 5

Total

%

1

31

778

4.0

356

3,805

9.4

2

269

8,736

3.1

593

8,064

7.4

3

259

7,621

3.4

488

6,878

7.1

4

226

7,093

3.2

393

6,064

6.5

5

222

6,664

3.3

360

5,239

6.9

6

158

5,348

3.0

317

4,723

6.7

 

1,165

36,240

3.22

2,507

34,773

7.21

2.12 Acknowledgments.—It is obvious that a program of this complexity and magnitude depends for its success on the efforts of many people in addition to the authors of this monograph. In particular, our heartfelt appreciation is due Lt. Col. Carl F.Tessmer, Dr. Grant Taylor, Dr. John Morton, and Dr. F.H. Connell, who, as successive directors of the Commission faced with the difficult task of balancing many demands on limited facilities and personnel, were always most generous in their treatment of the Genetics Program. Without the staunch, long-time support of the Committee on Atomic Casualties of the National Research Council and the Division of Biology and Medicine of the U.S. Atomic Energy Commission, this program could not have been undertaken nor continued. In particular, we are indebted to Drs. Max Zelle, Harold Plough, and Earl

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Green, who, during their tenure as geneticists with the Division of Biology and Medicine of the Atomic Energy Commission, gave freely of their time and advice, and to Dr. A.E.Brandt, who, as biometrician to the Health and Safety Division of the New York Operations Office of the U.S. Atomic Energy Commission, offered a number of helpful suggestions. Turning now to Japan, it is a pleasure to mention the support received from various members of the Public Health and Welfare Section, GHQ, SCAP, and in particular from Brigadier General C.F.Sams, Chief of the Section, Col. Harry Johnson, Chief, Medical Service Division, and Mr. L.V.Phelps, Chief, Health Statistics Division. Dr. Harry C. Kelley, Deputy Chief, Scientific and Technical Division, Economic and Scientific Section, GHQ, SCAP, was an important link with Japanese science. Our special thanks are due Dr. M.Tsuzuki, who, as Chairman of the Medical Section of the Special Committee for the Investigation of the Effects of the Atomic Bombs of the Japanese National Research Council, assisted the work in many ways during the early days of the study. Later, when the Japanese National Institute of Health entered into the picture, Dr. R.Kobayashi, Director of the Institute and Dr. I.Nagai, Chief of the Atomic Bomb Section, were most helpful. Dr. H.Maki, as Director of the National Institute of Health staff in Hiroshima and Nagasaki, was an unfailing source of counsel in meeting local problems as they arose. Dr. Taku Komai served as a frequent and greatly appreciated source of contact with Japanese geneticists. The statistical analysis profited greatly from discussions and correspondence with Dr. C.R.Rao, Dr. H.L.Lucas, Dr. Robert Krooth, Dr. Marvin Kastenbaum, and Mr. Donald E.Lamphiear. Mrs. Betty Hsiao provided invaluable assistance in the computations. In addition the following persons have been so kind as to read and criticize all or part of the manuscript: Dr. H.Fairfield Smith, Dr. I. Olkin, Dr. C.C.Craig, Dr. P.S.Dwyer, Dr. Joseph Ullman, Dr. Curt Stern, Dr. L.S.Penrose, Dr. Bradford Hill, and Dr. P.Armitage. The burden of preparing the manuscript has been substantially lightened by the conscientious assistance of Miss Frances Davidson, Mrs. Jane Schneidewind, Mrs. Barbara Seijas, and Miss Grace Yesley. We are grateful to the Rockefeller Foundation for defraying publication expenses through a grant to the National Academy of Sciences. Finally, to the literally hundreds of other people, American and Japanese employees of the Commission and local Japanese, who have contributed so much to whatever success this program may have enjoyed, our sincerest thanks.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Chapter III

A COMPARISON OF HIROSHIMA AND NAGASAKI

HIROSHIMA, situated facing the Inland Sea on the southern coast of the Japanese island of Honshu, was at the time of the atomic bombing a city of approximately 350,000 inhabitants (including military personnel). Nagasaki, located on the western side of the Japanese island of Kyushu, was at that time a city of approximately 250,000 persons. In addition to the obvious differences in size and location, there are a number of other respects, pertinent to this study, in which the two cities are not comparable.

3.1 The peopling of Japan; possible differences between the inhabitants of Honshu and Kyushu.—The origin of the present-day inhabitants of Japan, like the origins of so many of the peoples of the earth, is a tantalizing riddle. Most standard reference works on the subject recognize the possibility of three distinct prehistoric streams of immigration into the Japanese islands, one entering Kyushu from the south by way of Formosa and the Ryukyu Islands, and ultimately derived from southern China,1 a second entering northern Kyushu and southern Honshu from Korea, and ultimately derived from Manchuria, and a third stream, represented by the contemporary Ainu and having affinities with the present-day inhabitants of Siberia, northern Russia, Finland, and northern Sweden, entering from the north (Munro, 1908; Brinkley, 1915; Murdoch, 1926; Sansom, 1943; Beardsley, 1955). But while Japanese mythology, the earliest written records, and the archeological findings all supply reasonably good evidence for such waves of immigration towards the end of the Stone Age, it is not at all clear whether these immigrants found Japan already inhabited and, if so, the provenance of these very earliest inhabitants (cf. Kiyono, 1949). Almost equally uncertain is the relative timing of these waves of immigration, and the proportions in which these waves, together with the possible even earlier inhabitants, blended to form the modern Japanese type. Suffice it for our purposes to recognize the possibility that some thousands of years ago there existed significant anthropological differences between the inhabitants of the vicinity of Nagasaki in southern Japan and of Hiroshima in central Japan, and the further possibility that today, despite the many historical developments which would tend to obliterate such differences, some vestige still remains.

3.2 Non-Japanese elements in the two cities. —The present-day inhabitants of Nagasaki may differ genetically from those of Hiroshima for reasons other than just outlined. Historically, Nagasaki is pre-eminent among all Japanese cities as a point of contact with Western culture. The problem to which we must now address ourselves briefly is the question of the extent to which these contacts have been accompanied by intermarriages and arrangements of convenience which have left a lasting imprint on the biotype of the inhabitants of this area.

3.2.1 Early Nagasaki contacts with the West.—From our standpoint, the history of these contacts is best divided into three periods. The first of these begins in 1542 or 1543, when three Portuguese traders who had taken passage in a Chinese junk for Liampo were driven north by a typhoon and landed on a small island off the coast of southern Japan. Within a few years they were followed by Portuguese trading ships, which also brought Jesuit priests from the missions at Macao and Goa. The next 100 years were characterized by a considerable Japanese trade with the West, much of it funneling

1  

Some have suggested Indonesia, Malaysia, or Polynesia.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

through Nagasaki. This trade was at first dominated by the Portuguese, but later shared in by Spanish, Dutch, and English ships. Concurrently, Portuguese Jesuit and Spanish Franciscan missionaries were busy. The activities of these missionaries, at first readily tolerated, at length reached the point where, both in terms of numbers of converts and political overtones, they were felt by the Tokugawa shogunate to pose a threat to the stability of Japan. In 1612, an earlier ban against Christianity was for the first time rigorously enforced. The Christian converts who refused to renounce their faith—and there were many—were vigorously persecuted. At the same time, the entrance of foreigners into Japan, as well as their movement about the country, was increasingly restricted. In 1636, Japanese ships and Japanese individuals were forbidden to go abroad. By 1639, all foreigners are reported to have been expelled from Japan, and the country had embarked on an era of self-imposed seclusion.

3.2.2 The Dutch on Deshima.—This severance of ties with the West was not quite complete. From 1640 until 1853, when Commodore Perry was successful in the first steps at re-establishing intercourse with the West, the Dutch, presumably because of the non-political and non-religious nature of their prior activities, were permitted to maintain a small trading station on Deshima in Nagasaki. This span of 213 years is the second of the three periods we must recognize. During this period, Chinese were also permitted to trade at Nagasaki and in much greater numbers than the mere handful of Dutch. Thus, Kaempfer (1728) describes a Chinese section of Nagasaki with upwards of 1,000 inhabitants, and further estimates, on the basis of the number of junks coming to Nagasaki and their size, that in the years 1683 and 1684 (which may or may not be representative of previous years) there were “for each year not less than 20,000 Chinese visitors.” A year later trade with China was, at least officially, much more restricted, to 70 junks per annum with crews of not more than 30. Throughout the next century and a half the Dutch continued as in the past to send on the average one or two ships a year to Nagasaki, while Chinese activities were still further restricted, only a dozen junks a year being permitted to visit the port by 1820 (Murdoch, 1926).

3.2.3 From the reopening of Japan to World War II.—The third period may be dated from 1853 to the outbreak of World War II. Perry in his negotiations of 1853 and 1854 for port facilities declined the Japanese offers of Nagasaki, apparently feeling that its past would be more hindrance than help in establishing his new era, but under an agreement negotiated in 1857 by Harris, the first American Consul-General to Japan, Nagasaki became one of three treaty ports into which American ships could enter freely. However, the Dutch, from their beachhead at Deshima, had already profited from Perry's visit. In 1853, immediately following Perry's visit, the Japanese entered into negotiations with the Dutch for the purchase of men-of-war. In 1855, the Dutch presented the Japanese with the Soembing, the first unit of Western construction to be acquired by the Japanese Navy. In that same year, the Japanese established a navigation school and ship-building yard in Nagasaki, instruction being furnished by 22 Dutchmen. In 1857 another Dutchman, Dr. Pompe van Meerdervoort, assumed charge of a newly established school of medicine.

During the first decade following Perry's visit, while Japanese relations with foreigners were most unsettled, the number of Europeans in Nagasaki remained quite small, but beginning with the mid-1860's, and particularly after the initiation of the pro-foreign Meiji era in 1868, there arose a sizeable “foreign colony” in Nagasaki, largely concentrated on land on the eastern side of the harbor specifically set aside for this purpose. We have found it difficult to locate any exact data concerning the “foreign colony” between the reopening of Japan and 1897, with the exception of some statistics for 1864–1870, 1882, and 1889. Concerning the situation after 1897 there appears to be considerable information, but unfortunately sometimes conflicting in nature. This conflict is not so great as to invalidate an approximate evaluation of certain matters pertinent to this study.

Table 3.1 summarizes the earliest complete data on this period which we have been able to locate, made available through the courtesy of the Nagasaki Prefectural Library. Between 1864 and 1870 there were on the average 150–200 Occidentals in the city, as well as a rapidly increasing number of Chinese, the number of the latter growing from 141 in 1864 to 366 in

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

1870. The biological significance of this number of persons can only be evaluated in terms of the city's total population, which in 1870 was given as 29,127 (Nagasaki since the Restoration, 1925). Occidentals thus accounted for approximately 0.6 per cent of the population at this time.

Data concerning only two years during the interval 1871–1896 have come to our attention. In 1882, when the population of Nagasaki was 39,963, the total foreign population had risen to 829. Of these, six hundred and some were Chinese and the rest Occidentals, including approximately 100 English, 30 French, 30 Americans, and some Russians, Austrians, Dutch, and Danes (Nagasaki since the Restoration, 1925). By 1889, when the city population

TABLE 3.1 POPULATION FIGURESBY NATIONALITYFOR FOREIGNERS RESIDENTIN NAGASAKI CITYBETWEEN 1864 AND 1870 (Abstracted from “Records of the Investigation by Nationality of Foreigners Resident in Nagasaki City—1864 through 1879,” from the official files of the Nagasaki magistrate's office)

 

Foreign populations

 

Year

Britain

U.S.A.

Germany

France

Russia

Portugal

Holland

Others

Chinese

Total

1864

49

37

10

10

1

24

141

272

1865

66

33

10

11

2

3

26

246

397

1866

66

36

15

16

5

38

1

224

401

1867

66

35

19

14

5

30

4

305

478

1868

81

39

20

15

8

30

6

375

574

1869

79

23

21

15

1

5

23

2

333

502

1870

89

29

25

14

1

6

20

3

366

553

was 54,502, there were 354 Occidentals and 701 Chinese in residence (Nagasaki since the Restoration, 1925).

Beginning with 1897, more complete data became available. Table 3.2 summarizes city and prefectural census reports from 1897 to 1923. 2 The data are drawn from different sources, the city data from a book issued by the municipal government in 1925 (Nagasaki since the Restoration), the prefectural data from the Japanese Empire Statistical Annual (Nihon Teikoku Tokei Nenkan). It is apparent that most of the foreigners residing in Nagasaki prefecture were concentrated in the city proper, making it possible in an approximate treatment such as this to substitute prefecture for city figures where the latter are lacking. That one or the other or both sets of data are not completely accurate is suggested by the fact that for several of the years, city figures exceed those for the prefecture, a manifest impossibility unless “residence” is defined differently in the two sets of data, a point not entirely clear. City figures are not available after 1923, but those for the prefecture indicate a slow, continual increase in the number of Occidentals residing in the city, as illustrated by the figures for 1930 given in Table 3.3. Throughout the first 40 years of this century, something like 0.2 per cent of the population of the city was Occidental, and an additional 0.7 per cent, Chinese.

The ethnic breakdown of the figures for two representative years, 1910 and 1930, is indicated in Table 3.3. These simple totals fail to provide a true insight into the “dynamics” of the situation. In Table 3.4 figures based on the 1920 census report are given concerning the age composition and the marital status of four of the principal ethnic groups, as well as for the total foreign population. Attention is directed towards the high proportion of unmarried males in the 20–39 age interval. Furthermore, in evaluating the significance of the number of married women, it should be borne in mind that in cases-of mixed marriages, the wife and children assumed the citizenship of the husband (Izumi, 1921; Sasano, 1921).

3.3 The biological influence of “foreigners” on Nagasaki and Hiroshima. —It is a manifest absurdity to attempt to quantitate in any way the extent to which foreign contacts during these three periods left a biological imprint on the face of Nagasaki. However, one is perhaps permitted certain impressions. It seems unlikely for at least two reasons that the foreigners who visited Japan during the first of the three periods defined above contributed in any significant way to the genetic constitution of the present-day inhabitants of this area. For one thing, the

2  

The prefecture is a geographical unit roughly corresponding to the state of the U.S.A.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

systematic suppression of Christianity, thought to involve the death of at least 20,000 Japanese converts, and perhaps 100,000 or even more (Kaempfer, 1728; Murdoch, 1926; Sansom, 1943), may have decimated the very group in which the offspring of Caucasian-Japanese unions were most apt to be found.3 For another thing, the Japanese, during the period ending in 1639 when they were ridding themselves of foreign influences, were systematic in their uprooting of all traces of the intruders, to the extent that, among other actions, it is recorded that they exiled to Macao in 1636 some 287 women and children known to be related to the Portuguese by marriage or birth (Kaempfer, 1728; Woolley, 1881).

TABLE 3.2 THE “FOREIGNAND TOTAL POPULATIONOF NAGASAKI CITY, ANDTHE “FOREIGN” POPULATIONOF NAGASAKI PREFECTURE, 1897–1923

 

Foreign population, city

 
 
 

Year

Households

Males

Females

Total

Foreign population, prefecture

Total population, city

1897

290

851

271

1,122

73,974

1898

561

1,218

342

1,560

113,307

1899

731

1,345

357

1,702

1,743

120,865

1900

662

1,442

476

1,918

1,983

129,597

1901

526

2,104

2,037

142,811

1902

542

1,304

355

1,659

1,725

148,882

1903

640

1,334

409

1,743

1,698

154,727

1904

538

1,170

367

1,537

1,579

159,041

1905

487

1,121

365

1,486

1,535

163,324

1906

430

1,057

448

1,505

1,553

168,436

1907

416

1,061

402

1,463

1,523

173,118

1908

380

867

395

1,262

1,282

175,936

1909

321

800

419

1,219

1,290

176,970

1910

326

756

389

1,145

1,186

178,074

1911

274

639

329

968

1,127

179,257

1912

276

657

370

1,027

154,351

1913

318

754

396

1,150

1,189

160,450

1914

328

800

405

1,205

164,272

1915

304

763

392

1,155

1,200

174,077

1916

314

772

403

1,175

1,189

182,695

1917

316

772

405

1,177

1,173

188,006

1918

345

804

393

1,197

1,261

197,500

1919

347

810

397

1,207

1,311

205,958

1920

351

810

403

1,213

1,342

233,813

1921

355

806

406

1,212

1,217

245,954

1922

362

822

417

1,239

1,261

256,316

1923

370

832

423

1,255

1,303

264,669

It is characteristic of the thoroughness of the Japanese in ridding themselves of foreign influences that during the second of the three periods we have defined, the Dutch were forced to live on a small, artificial island in the Nagasaki harbor, termed Deshima, measuring some 600×240 feet. The number of Dutch in residence was severely limited, usually to about 10 to 20, and the movements of these carefully restricted (cf. Kaempfer, 1728). But the Japanese are above all else realists. Alone among the Japanese people, prostitutes were permitted to visit Deshima, and periodically such of the Dutch as desired—their numbers perhaps swelled by the arrival of a ship—were permitted to visit Maruyama, then (and still) the brothel district of Nagasaki. These activities, like everything else the Dutch did, were carefully noted. Thus it is a matter of record that in one year (the 7th year of Kyoho, 1722) there were 270 Dutch visits to Maruyama—during that same year there were 20,738 Chinese visits (Boxer, 1950). In view of the practice of abortion and infanticide during the Tokugawa Era and the official attitude toward foreigners, it would be strange if any considerable number of children

3  

Exact data on this point are of course unobtain-able. From our standpoint it is important to recognize that the permanent flight of Christians from Nagasaki to more inaccessible regions to escape persecution may, from the genetic standpoint, have done as much to obliterate any effects of interbreeding in that city as the actual death of Christians.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

from such relationships readied maturity. The few of whom there is any record are cited in reference works primarily as “curiosities” (e.g., Thunberg, 1795, 1796).

It is more difficult to evaluate the extent to which racial admixture occurred during the period ushered in by Commodore Perry's visit. The fraction of one per cent of the Nagasaki population which has been Occidental has been a very mixed group—diplomats, missionaries,

TABLE 3.3 THE ETHNIC COMPOSITIONOF THE FOREIGN COMPONENTOF NAGASAKI CITY, FORTHE YEARS 1910 AND 1930 [The figures for 1910 are based on the city alone (Kitano, 1911), while those for 1930 on prefectural census reports.]

 

Year

 
 

1910

1930

 

Nationality

Males

Females

Total

Males

Females

Total

English

52

43

95

129

57

186

American

31

48

79

84

35

119

French

30

12

42

14

13

27

Russian

17

21

38

9

9

18

Danish

7

9

16

14

11

25

German

17

11

28

2

4

6

Portuguese

3

6

9

2

3

5

Italian

9

4

13

3

5

8

Austrian

2

4

6

Turk

2

1

3

1

1

Rumanian

2

5

7

Norwegian

6

4

10

30

1

31

Bulgarian

1

1

Dutch

31

5

36

Polish

8

1

9

Belgian

1

1

Swedish

2

4

6

Swiss

2

2

4

Canadian

2

2

Subtotal

178

169

347

334

150

484

Chinese

578

220

798

1,883

441

2,324

Other

1

1

Totals

756

389

1,145

2,218

591

2,809

teachers, and commercial persons—many of whom, of course, did not intermarry or otherwise contribute to the Nagasaki gene pool. However, in addition to these permanent residents, there were relatively many transient sea-men. The Russian fleet was stationed in Nagasaki during the winter months prior to the Russo-Japanese War in 1904. The intellectual climate of Japan during the late nineteenth and early twentieth centuries was characterized by the enthusiastic acceptance in some quarters of many aspects of Western civilization—there was apparently no particular opprobrium attached to mixed marriages or even temporary arrangements of convenience, as witnessed by the well-known story of Madame Butterfly, the locale for which was Nagasaki. One can state with considerable assurance that limited opportunities for racial admixture existed in Nagasaki between 1870 and 19404—the data do not permit one to go much further.

These are the bare historical facts. To what extent the present-day inhabitants of Nagasaki differ from those of Hiroshima because of racial admixture can only be a matter for conjecture. On the face of the evidence, it seems very unlikely that at most more than a few per cent of the corporate genetic constitution of present-day Nagasaki is non-Japanese in origin. This conclusion is borne out by the fact that the published A-B-O blood group frequencies of

4  

The opportunities which arose during the Occupation, starting with the arrival of the First Marine Division in Nagasaki, are scarcely pertinent to the problem of the ancestry of those individuals forming the parentage of the children under study.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

TABLE 3.4 THE AGE COMPOSITIONAND ETHNIC STATUSOFTHE TOTAL FOREIGN POPULATIONOF NAGASAKIIN 1920, ASWELL AS OF THE FOUR PRINCIPAL ETHNIC GROUPSINTHIS POPULATION (From Naikaku tokei-kyoku [Cabinet statistical bureau], Census Report, 1930, V. 4, p. 40.) Abbreviations: T, total; U, unmarried; M, married; and WD, widowed or divorced.

 

All foreigners

Chinese

American

English

Russian

 

Age

Total

Total

Total

Total

Total

All ages

 

T

2,504

1,925

579

1,363

1,001

362

444

391

53

346

315

31

244

162

82

U

1,511

1,181

330

760

539

221

327

303

24

237

222

15

112

78

34

M

924

714

210

563

441

122

114

87

27

105

93

12

119

78

41

WD

69

30

39

40

21

19

3

1

2

4

4

13

6

7

0–4

 

T

192

101

91

152

82

70

11

6

5

5

4

1

16

5

11

U

192

101

91

152

82

70

11

6

5

5

4

1

16

5

11

M

WD

5–9

 

T

192

109

83

158

88

70

10

8

2

6

4

2

12

6

6

U

192

109

83

158

88

70

10

8

2

6

4

2

12

6

6

M

WD

10–14

 

T

165

91

74

127

76

51

7

4

3

6

2

4

10

6

4

U

165

91

74

127

76

51

7

4

3

6

2

4

10

6

4

M

WD

15–19

 

T

221

180

41

140

112

28

12

10

2

43

42

1

19

12

7

U

199

173

26

122

106

16

11

9

2

43

42

1

16

12

4

M

22

7

15

18

6

12

1

1

3

3

WD

20–24

 

T

442

395

47

150

125

25

155

148

7

92

91

1

35

26

9

U

352

338

14

94

88

6

140

138

2

83

83

26

24

2

M

88

56

32

54

36

18

15

10

5

9

8

1

9

2

7

WD

2

1

1

2

1

1

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

25–29

 

T

383

330

53

150

117

33

123

116

7

74

72

2

29

22

7

U

213

206

7

49

46

3

92

91

1

57

56

1

12

10

2

M

167

123

44

99

70

29

31

25

6

17

16

1

17

12

5

WD

3

1

2

2

1

1

30–34

 

T

296

245

51

142

119

23

66

60

6

39

34

5

41

28

13

U

87

80

7

21

21

36

34

2

14

13

1

11

9

2

M

202

159

43

116

94

22

30

26

4

25

21

4

28

17

11

WD

7

6

1

5

4

1

2

2

35–39

 

T

207

167

40

111

94

17

21

15

6

38

35

3

31

22

9

U

53

44

9

17

16

1

10

6

4

16

14

2

7

6

1

M

146

120

26

90

76

14

11

9

2

22

21

1

21

14

7

WD

8

3

5

4

2

2

3

2

1

40–44

 

T

128

99

29

70

56

14

12

9

3

16

14

2

19

13

6

U

11

7

4

2

2

2

2

1

1

1

1

M

112

90

22

64

52

12

10

7

3

15

14

1

18

13

5

WD

5

2

3

4

2

2

45–49

 

T

115

86

29

71

56

15

14

8

6

8

7

1

12

10

2

U

16

10

6

6

3

3

4

3

1

1

1

1

1

M

85

70

15

54

48

6

9

5

4

7

6

1

10

9

1

WD

14

6

8

11

5

6

1

1

1

1

50–54

 

T

69

47

22

40

31

9

2

1

1

9

4

5

10

8

2

U

12

7

5

6

5

1

1

1

2

1

1

M

47

39

8

31

26

5

1

1

5

3

2

7

7

WD

10

1

9

3

3

2

2

3

1

2

55–59

 

T

37

27

10

20

17

3

5

2

3

4

2

2

3

2

1

U

7

6

1

2

2

2

1

1

M

24

18

6

17

14

3

1

1

3

2

1

1

1

WD

6

3

3

1

1

2

1

1

1

1

2

1

1

60–

 

T

63

48

15

32

28

4

6

4

2

6

4

2

6

3

3

U

12

9

3

4

4

1

1

3

2

1

M

37

32

5

20

19

1

5

3

2

2

2

5

3

2

WD

14

7

7

8

5

3

1

1

1

1

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

persons living in Nagasaki do not differ strikingly from those of their neighbors, although one wonders about the selection for typing studies of “pure” Japanese (summary in Boyd, 1939). It is unfortunate that studies on the Rh gene frequencies are not available inasmuch as these, because of the difference between Caucasian and Oriental populations (summary in Mourant, 1954), would be expected to be especially revealing.

That there has been some admixture can scarcely be challenged. One who visits the three cemeteries where foreigners were customarily buried is impressed by the frequency with which there appear on the tombstones of the past three-quarters of a century Japanese female given names in combination with non-Japanese surnames. Unfortunately, the local church records, which might have been of real value in this connection, fared less well than the tombstones in the atomic holocaust. One of these cemeteries is the large and picturesque, semi-official “Foreign National” cemetery, conveniently subdivided into Russian, Dutch, English, etc., sections. There is a marked preponderance of males buried here. It would be passing strange if, during the 70 years preceding World War II, these men, even more than the casual sailors from so many ports, failed to leave a genetic heritage paralleling their socio-economic stamp.

Finally, some of the authors have the distinct impression of encountering from time to time in Nagasaki, individuals who, because of hair or eye color or facial conformation, strongly suggested Caucasian ancestry. Such persons are a very small minority but, in view of the general dominance in mixed Japanese-Caucasian marriages of the straight, black hair, the dark eyes, and the facial appearance of the Japanese, cannot be easily disregarded.

In striking contrast to Nagasaki, the Hiroshima area, although it has supplied relatively many emigrants to Hawaii and the U.S.A., has itself been characterized by very limited contacts with the West, even down to the time of World War II. It would seem that the possibility of a Caucasian element in this population may safely be ignored.

In addition to the possible role of historical (and pre-historical) factors in creating biological differences between the inhabitants of Hiroshima and Nagasaki, certain obvious present-day differences should be mentioned. We are indebted to Mr. Fu, Chinese Consul in Nagasaki in 1952, for the information that in February of that year there were 600 Chinese citizens in the city. These were not all “pure” Chinese; on the other hand, there were known to be many persons in Nagasaki whose ancestry was in part Chinese who no longer claimed Chinese citizenship. In Hiroshima there was no significant number of Chinese, but, by contrast, a relatively large “Korean colony,” numbering, according to data supplied by the Hiroshima Municipal Government, some 5,000 persons in January of 1952. There is reason to suspect that because of illegal entry, the number was actually somewhat larger. There were relatively few Koreans in Nagasaki.

3.4 The different impacts of the atomic bombs on the two cities.—There are important differences between Hiroshima and Nagasaki in respect to their experience with the atomic bombs.

3.4.1 Types of bombs.—Different kinds of bombs were used on the two cities, that dropped over Hiroshima being a uranium-235 bomb, whereas the one used against Nagasaki was composed of plutonium-239. As will be brought out in the next chapter, the radiation spectrum of these two bombs differed.

3.4.2 Effects of the bombs on the two cities.—The over-all effects of the atomic bombs on Hiroshima and Nagasaki have been adequately described elsewhere (British Mission, 1946; United States Strategic Bombing Survey, 1946; Los Alamos Scientific Laboratory, 1950; Oughterson et al., 1951). Suffice it to say here that both the mortality and the morbidity from the bombs differed markedly in the two cities. Because of the deterioration in Japanese vital statistics during the war and the destruction of records in consequence of the bombings, exact casualty figures will never be available. However, it is usually stated that in Hiroshima approximately 60,000 inhabitants were killed immediately or died within a few weeks of the effects of the explosion, and an additional 70,000 sustained overt injury. This figure may be a very conservative estimate of the total casualties for two reasons. As the headquarters of the Second Grand Army, the chief concentration of military power in Central ♂♀

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Japan, Hiroshima was a major “staging area” for the South Pacific theater of war. The elaborate facilities of the Second Army were almost completely destroyed. Because of war-time secrecy plus the deliberate destruction of surviving military records, the military casualties will never be known, but they number well into the thousands. In addition, on the day of the bombing there were a number of work parties from neighboring towns in the area. The total number of persons killed may exceed 100,000. With respect to Nagasaki, it is usually stated that there were approximately 33,000 civilian deaths, and 25,000 surviving injured. Nagasaki contained no military installations of any significance, so that the problem of accounting for military personnel does not exist for this city. Since many more records survived here than in Hiroshima, it is felt that the figures for Nagasaki are reasonably accurate.

The plutonium-type bomb detonated over Nagasaki actually had a greater explosive power than that used on Hiroshima. The reason for the greater number of casualties in the latter city is to be sought in large part in differences in the physical features of the two cities. Hiroshima is built on the triangular delta of the river Ota (Fig. 3.1). Only one small “mountain” (Hijiyama, height 69 meters) breaks the flatness of the terrain occupied by the great majority of the city. As indicated in Fig. 3.1, the bomb was detonated not far from the “center” of this delta. The topography of Nagasaki is very different (Fig. 3.2). The city lies at the head of a long, narrow bay, running up from which there is a “mountain,” with a valley on either side. The city extends along both sides of the bay and up into the two valleys, thus roughly resembling in its outlines the letter “X.” As indicated on the map, the bomb was detonated over one of the valleys, in which there was a heavy concentration of war industry (and, incidentally, the largest Christian colony and church in Japan, and the Nagasaki Medical School and its hospital). The serious effects of the bomb were largely confined to this one valley.

The official statistics concerning the effects of the bombs are paralleled by the experience of the ABCC in the two cities. For instance, in consequence of a Radiation Census carried out in 1949, together with certain later supplementary data, it can be estimated that in 1949 there were some 31,000 inhabitants of Hiroshima who had been within 2,000 meters of the hypocenter at the time of the explosion, whereas the corresponding figure for Nagasaki was 9,850. It can be further estimated that approximately 6,000 persons then resident in Hiroshima, and 2,000 in Nagasaki, had shown such symptoms of relatively heavy irradiation as epilation, purpura, and/or oropharyngeal lesions following the bombings (ABCC Semi-Annual Report, January-June, 1954). As can be seen from Table 2.1, among the parents of children falling within the scope of the Genetics Program, there were roughly twice as many relatively heavily irradiated in Hiroshima as in Nagasaki.

3.5 The development of the ABCC program in the two cities.—Despite the number of persons on the ABCC roster (p. 2), there was, considering the magnitude of the total problem to be attacked, a chronic shortage of trained personnel, this imposed in part by budgetary considerations and in part by recruitment difficulties. The original plan had been that the ABCC would develop programs in Hiroshima and Nagasaki which would be quite comparable in size. From the first, however, the concentration of personnel and facilities in Hiroshima far outstripped that in Nagasaki. The reasons were chiefly two: (1) Given the personnel shortages alluded to above, and the greater number of relatively heavily irradiated survivors in Hiroshima, it was obviously more economical of available personnel to concentrate them in Hiroshima. (2) For a number of reasons which need not be entered into here, logistical problems, including the matter of housing, were less serious in Hiroshima. To those of your authors who found themselves curiously stirred by the colorful and dramatic history of Nagasaki—a history whose shadows confronted one at many turns—it has always seemed regrettable that practical considerations dictated putting so much more effort into Hiroshima.

Because of the clear need from the outset for all the “genetic” data which could be collected from both cities, the Genetics Program came closer to an equality of effort in the two cities than did any other facet of the ABCC's activities. Every possible attempt was made to ensure the comparability of the genetics programs in

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Figure 3.1—The topography of the Hiroshima City region, with particular reference to distance from the hypocenter of the atomic bomb explosion. Although the grid is laid out in 1,000-yard intervals, the concentric rings indicate distance from the hypocenter in 1,000-meter intervals.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

FIGURE 3.2—The topography of the Nagasaki City region. Explanation as for Figure 3.1.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Hiroshima and Nagasaki. The two chief factors in this effort were the formulation of a rather rigid set of procedures to be adhered to in the two cities, and frequent exchanges of personnel. It is felt that in the main, this effort was successful. On the other hand, as will become evident in Chapter V, some of the reported differences in pregnancy termination between the two cities may not actually reflect true biological differences.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Chapter IV

THE CRITERIA OF RADIATION EMPLOYED IN THE STUDY

THE present chapter will be devoted to an examination of the available and practical criteria for evaluating the amount of radiation received by individuals exposed in Hiroshima and Nagasaki to the effects of the atomic bombs.

4.1 The complicated nature of the injuries sustained by some survivors; “disaster effect” vs. “radiation effect.”—The detonation of an atomic bomb may be harmful to persons in its vicinity for a variety of reasons. The air blast may inflict injury directly or secondarily, from flying debris and falling walls and roofs. The thermal radiation produces severe burns, and, in addition, further burns may be sustained as a result of fires kindled by the explosion. Under the conditions prevailing in Hiroshima and Nagasaki, serious secondary infection of these burns was the rule rather than the exception. Finally, the explosion is accompanied by the release of a variety of deleterious high energy radiations, particularly X-rays, gamma rays, and fast and slow neutrons. The complex manner in which these various noxious agents affect persons exposed to the explosion of an atomic bomb is well depicted in the Report of the Joint Commission for the Investigation of the Effects of the Atomic Bomb in Japan (Oughterson et al., 1951).

Moreover, in the wake of such a cataclysmic event as the detonation of an atomic bomb over a city, come certain well recognized accompaniments of any large-scale disaster, notably, disturbed nutrition and increased morbidity from disease. These “disaster effects” are here so complexly intertwined with the primary event that it will be difficult, if not in fact impossible, in any analysis of atomic bomb sequelae, to effect a realistic and completely satisfactory separation of the relative importance of what transpired at the time of the bombing and what transpired in the next several months. In this particular instance, the general problem of disentangling primary and secondary effects upon the manner in which pregnancies are terminating is still further complicated by the fact that certain delayed somatic effects of irradiation have been shown to occur in the population under study. The “late” effects include leukemia (Folley, Borges, and Yamawaki, 1952; Lange, Moloney, and Yamawaki, 1954; Moloney and Lange, 1954) and cataracts (Cogan, Martin, and Kimura, 1949; Sinsky, 1955). Although both of these conditions affect only small numbers of the more heavily irradiated survivors, they do occur in the group most critical to this study. It seems entirely possible that there are other late sequelae, still undefined, which may influence reproductive behavior.

In subsequent chapters an attempt will be made to correlate exposure history with a variety of possible indicators of genetic damage. However, it must be clearly understood that if a significant association can be shown to exist, this demonstration of itself does not enable one to conclude that exposure to the bomb has genetic consequences; the latter conclusion is justified only if an effect remains after the various other factors associated with the irradiation have been assigned their proper role.

4.2 The question of residual radiation following an atomic bombing.—The ionizing radiation of an atomic bomb explosion is released over a relatively brief period, of approximately 100 seconds. However, as a result of the contamination of the area due to the fall-out of radioactive by-products of the explosion, as well as secondarily induced radioactivity, there is a certain amount of residual radioactivity in an area over which a bomb has been detonated.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

The estimation of the amount of residual radiation at Hiroshima and Nagasaki presents many difficulties. The distribution of residual radiation around the hypocenter in the two cities was asymmetric, the exact pattern depending on local meterological details (Warren, 1945; Warren, 1946). Based on the observed residual radioactivity at intervals following the bombing, Warren (1945) has estimated that the maximum irradiation due to residual radioactivity was in Hiroshima during the first 60 days following the bombing the equivalent of 4.2r, and in Nagasaki during the first 47 days, the equivalent of 14.2r. Wilson (1951), using similar data, has suggested that in Hiroshima the maximum cumulative dose of residual radiation at distances greater than 1,000 feet (300 meters) was not more than 10r, with somewhat higher doses prevailing in Nagasaki, especially in a fall-out area extending eastward from the hypocenter, where the cumulative dose from radioactivity might have amounted to 100r. Irradiation of this latter degree would only be experienced by individuals establishing continuous residence near ground zero immediately after the bombing, a situation which rarely, if ever, obtained, although persons coming into the area later or intermittently might of course receive lesser amounts. On the other hand, there are persistent Japanese reports of members of rescue parties and others not actually in the two cities at the time of the bombing later developing symptoms of radiation sickness, or leucopenia (Japan Science Council, 1951; Appendix 18, ABCC Semi-Annual Report, 1 January 1952–30 June 1952); this would suggest a dose of 200r (cf. Sec. 4.8). This apparent conflict of evidence remains unresolved at present; we shall adhere for the time being to the more conservative view concerning residual radioactivity. By and large, individuals exposed to the effects of the atomic bombs tended to leave the area as rapidly as possible. Accordingly, for the purposes of this study it has been felt that although exposed individuals and also those entering the city immediately after the bombings may have been subjected to some residual radiation, by comparison with the amount absorbed by those present at the moment of the explosion, this was on the average small and could be disregarded. Moreover, it might be pointed out that in the case of an individual engaged, e.g., in rescue work in Hiroshima or Nagasaki during the first few days following the bombing, it appears impossible to reconstruct his behavior during those several days in a fashion which would permit a realistic estimation of the total radiation dose which he absorbed during this period.

4.3 Factors determining the nature of the radiation data collected in this study.—At the time this study was being planned, in 1947, no data of any sort concerning the types of radiation emitted by an atomic bomb and the distance-dosage relationship were available to any of those closely connected with the program. In retrospect, in view of the many revisions the physical estimates have undergone, this is perhaps fortunate. Be that as it may, under the circumstances extensive recourse was had to the findings of the Joint Commission, then available in preliminary form. These findings, as later published (1951), established the following facts of importance in the design of the present observations:

4.3.1 The syndrome of radiation sickness due to whole-body irradiation.— Although the therapeutic uses of radiation had long since laid the groundwork for an appreciation of the signs and symptoms of “radiation sickness,” it remained for the observations of the Joint Commission to provide the definitive description of this entity. The findings, of course, vary according to the radiation dose. We are not here concerned with the early effects of lethal doses of whole-body irradiation, since persons receiving such doses can scarcely provide the parentage for a study of this nature. The Joint Commission observed that individuals receiving relatively large but yet sublethal doses of irradiation (as judged by proximity to the hypocenter in the absence of marked shielding) may or may not develop nausea and vomiting within a few hours of their exposure. There follows a relatively asymptomatic period of approximately two weeks, after which characteristic signs and symptoms appear. Some of these, such as fever, malaise, anorexia, nausea, and vomiting, have a low degree of specificity, being present in a wide variety of diseases. Other findings were much more specific. The chief among these are summarized in Table 4.1. These are figures for all survivors, irrespective of the amount of shielding which protected them. Let us restrict ourselves, for the moment, to a consideration of the findings in persons reporting themselves

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

TABLE 4.1 FREQUENCYOF OCCURRENCEOF CERTAIN SYMPTOMSIN PERSONS ALIVE 20 OR MORE DAYS FOLLOWINGTHE ATOMIC BOMBINGS, AS RELATEDTO DISTANCEFROM THE HYPOCENTER (Data of Joint Commission)

Hiroshima

 

Epilation

Purpura

Oropharyngeal lesionsa

Necrotic gingivitis

Diarrheab

Bloody diarrhea

Other hemorrhage

 

Ring

Distance (meters)

Total no. of people

No.

%

No.

%

No.

%

No.

%

No.

%

No.

%

No.

%

1

0–1,000

749

520

69.4

366

48.9

458

61.1

77

10.3

375

50.1

80

10.7

285

38.1

2

1,100–1,500

1,125

341

30.3

241

21.4

381

33.9

43

3.8

476

42.3

75

6.7

197

17.5

3

1,600–2,000

1,824

151

8.3

78

4.3

286

15.7

12

0.7

666

36.5

99

5.4

112

6.1

4

2,100–2,500

1,450

69

4.8

27

1.9

230

15.9

16

1.1

519

35.8

95

6.6

94

6.5

5

2,600–3,000

700

16

2.3

13

1.9

105

15.0

1

0.1

260

37.1

34

4.9

41

5.9

6

3,100–4,000

576

7

1.2

7

1.2

39

6.8

0

0

134

23.3

13

2.3

22

3.8

7

4,100–5,000

239

0

0

4

1.7

21

8.8

0

0

59

24.7

2

0.8

5

2.1

Total

0–5,000

6,663

1,104

16.6

736

11.0

1,520

22.8

149

2.2

2,489

37.4

398

6.0

756

11.3

9c

Over 5,000

219

0

0

1

0.5

16

7.3

1

0.5

67

30.6

2

0.9

8

3.7

Grand total

6,882

1,104

16.0

737

10.7

1,536

22.3

150

2.2

2,556

37.1

400

5.8

764

11.1

Nagasaki

 

Epilation

Purpura

Oropharyngeal lesionsa

Necrotic gingivitis

Diarrheab

Bloody diarrhea

Other hemorrhage

 

Ring

Distance (meters)

Total no. of people

No.

%

No.

%

No.

%

No.

%

No.

%

No.

%

No.

%

1

0–1,000

789

249

31.6

168

21.3

275

34.9

20

2.5

337

42.7

54

6.8

110

13.9

2

1,100–1,500

1,882

460

24.4

324

17.2

607

32.3

33

1.8

736

39.1

86

4.6

233

12.4

3

1,600–2,000

1,034

128

12.4

92

8.9

200

19.3

16

1.5

358

34.6

56

5.4

78

7.5

4

2,100–2,500

672

41

6.1

24

3.6

101

15.0

4

0.6

224

33.3

23

3.4

36

5.4

5

2,600–3,000

644

16

2.5

7

1.1

84

13.0

6

0.9

195

30.3

28

4.3

18

2.8

6

3,100–4,000

1,141

16

1.4

17

1.5

121

10.6

1

0.1

268

23.5

21

1.8

28

2.5

7

4,100–5,000

265

1

0.4

1

0.4

19

7.2

0

0

23

8.7

3

1.1

5

1.9

Total

0–5,000

6,427

911

14.2

633

9.8

1,407

21.9

80

1.2

2,141

33.3

271

4.2

508

7.9

9c

Over 5,000

194

0

0

0

0

5

2.6

0

0

23

11.9

1

0.5

2

1.0

Grand total

6,621

911

13.8

633

9.6

1,412

21.3

80

1.2

2,164

32.7

272

4.1

510

7.7

aIncludes necrotic gingivitis.

bIncludes bloody diarrhea.

cThere is no ring 8 in the Joint Commission system of designating distance.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

within 1,000 meters of the hypocenter. From the standpoint of distinctiveness, two symptoms —epilation and purpura—are outstanding. Oropharyngeal lesions also were frequently encountered. Diarrhea, while reported by large numbers of persons, could, at 20 days after the bombing, in any individual case be as well attributed to the poor hygienic conditions following the bombing as to the bomb itself, and does not seem to be a satisfactory symptom on which to base a study. Bloody diarrhea is a somewhat more reliable symptom, but still, from the findings of the Joint Commission, less useful than the other three symptoms already discussed.

Further evidence as to the relative validity of the findings listed in Table 4.1 as indicators of radiation exposure comes from an analysis of the manner in which the various findings tended to be associated. Epilation and petechiae were more highly associated than any other pair of symptoms in both cities. The next highest associations observed were, in both cities, epilation with oropharyngeal lesions, and petechiae with oropharyngeal lesions.

On the basis of these findings, it was felt that the appearance of epilation, petechiae, or oropharyngeal lesions, singly or in combination, within three months of the bombing, provided a relatively specific and objective yardstick of the absorption of a certain amount of radiation, such as could be employed in the present study (see also, inter alia, Warren and Bowers, 1950; Los Alamos Scientific Laboratory, 1950; vor der Bruegge, 1952; Hempelmann, Lisco, and Hoffman, 1952). Although exact data are lacking, it seems likely, on the basis of animal data, that there is considerable individual variation in susceptibility to these symptoms, a point which must of course be borne in mind when we come later to the problem of estimating radiation dosages. It will be noted that there are significant differences between Hiroshima and Nagasaki in the percentages of persons exhibiting certain symptoms subsequent to exposure within 1,500 meters of the hypocenter. These differences are customarily attributed primarily to local differences in shielding factors (see below), but may also be due in part to actual dose differences.

4.3.2 The relation between distance from the hypocenter and radiation dosage.— Although the intensity of radiation obviously must decrease with distance from the hypocenter, the exact form of the distance-dosage relationship in Hiroshima and Nagasaki remains to this day uncertain. In part this is due to inadequate information concerning certain physical properties of these atomic explosions, in part to lack of detailed information concerning atmospheric moisture content at the time of the explosion. Furthermore, there is the possibility that the distance-dosage relationship is not the same in all radii from the hypocenter. Be this as it may, at the time this study was planned it was clear from such data as are given in Table 4.1, concerning the relationship between the occurrence of certain of the symptoms described above and distance from the hypocenter, that it would be important to record position at the time of the bombing as accurately as possible.

4.3.3 The role of shielding in determining radiation dose.—The third type of information thought to be especially valuable in estimating radiation dosage concerned the amount of shielding protecting the individual from the effects of the explosion. Table 4.2 illustrates some of the findings of the Joint Commission in this respect. For the sake of brevity, only the Hiroshima data are reproduced; the findings in Nagasaki were essentially similar. An obvious question which had to be disposed of early in the design of the program concerned the elaborateness of the shielding data to be collected. Obtaining a complete shielding history can be quite time consuming. Theoretically, knowing the distance-dosage relationship and the precise shielding, one can arrive at a relatively accurate estimate of the amount of irradiation received by an individual. We have already mentioned the uncertainties surrounding the distance-dosage relationship. These uncertainties are particularly acute as regards the neutron component of the radiation spectrum, a component which in animal experiments has been shown to have a high relative biological effectiveness with respect to genetic effects. Furthermore, in the authors' opinion there is no realistic approach to the problem of radiation scatter and secondary radiation as a factor in the exact dosage received by any individual. Finally, there is room for reasonable doubt as to most individuals' abilities to reconstruct their exact positions at the time of so traumatic an event as this, and yet nothing less than such a reconstruction will suffice for a precise evaluation of shielding. With all these considerations in mind, it was

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

TABLE 4.2 THE EFFECTIVENESSOF SHIELDINGIN PROTECTING AGAINST RADIATION SICKNESSIN HIROSHIMA (Data of Joint Commission)

Outdoors or in Japanese-type buildingc

 

Epilation

Purpura

Oropharyngeal lesionsa

Necrotic gingivitis

Diarrheab

Bloody diarrhea

Other hemorrhage

 

Ring

Distance (meters)

Total no. of people

No.

%

No.

%

No.

%

No.

%

No.

%

No.

%

No.

%

1

0–1,000

570

434

76.1

310

54.4

356

62.5

67

11.8

301

52.8

66

11.6

240

42.1

2

1,100–1,500

960

315

32.8

209

21.8

305

31.8

37

3.9

405

42.2

66

6.9

179

18.6

3

1,600–2,000

1,633

145

8.9

73

4.5

225

13.8

10

0.6

613

37.5

90

5.5

100

6.1

4

2,100–2,500

1,415

68

4.8

26

1.8

190

13.4

16

1.1

508

35.9

93

6.6

94

66

5

2,600–3,000

674

16

2.4

12

1.8

82

12.2

1

0.1

251

37.2

32

4.7

39

5.8

6

3,100–4,000

548

7

1.3

7

1.3

26

4.7

0

0

124

22.6

13

2.4

22

4.0

7

4,100–5,000

202

0

0

3

1.5

12

5.9

0

0

50

24.8

1

0.5

4

2.0

Total

0–5,000

6,002

985

16.4

640

10.7

1,196

19.9

131

2.2

2,252

37.5

361

6.0

678

11.3

9d

Over 5,000

46

0

0

1

2.2

8

17.4

0

0

18

39.1

0

0

4

8.7

Grand total

6,048

985

16.3

641

10.6

1,204

19.9

131

2.2

2,270

37.5

361

6.0

682

11.3

Indoors, in heavy building

 

Epilation

Purpura

Oropharyngeal lesionsa

Necrotic gingivitis

Diarrheab

Bloody diarrhea

Other hemorrhage

 

Ring

Distance (meters)

Total no. of people

No.

%

No.

%

No.

%

No.

%

No.

%

No.

%

No.

%

1

0–1,000

113

60

53.1

38

33.6

55

48.7

5

4.4

46

40.7

8

7.1

30

26.5

2

1,100–1,500

118

15

12.7

21

17.8

26

22.0

3

2.5

58

49.2

8

6.8

13

11.0

3

1,600–2,000

94

2

2.1

3

3.2

12

12.8

1

1.1

35

37.2

5

5.3

8

8.5

4

2,100–2,500

12

1

8.3

1

8.3

1

8.3

0

0

7

58.3

2

16.7

0

0

5

2,600–3,000

14

0

0

1

7.1

3

21.4

0

0

2

14.3

1

7.1

2

14.3

6

3,100–4,000

13

0

0

0

0

2

15.4

0

0

5

38.5

0

0

0

0

7

4,100–5,000

27

0

0

1

3.7

1

3.7

0

0

7

25.9

1

3.7

1

3.7

Total

0–5,000

391

78

19.9

65

16.6

100

25.6

9

2.3

160

40.9

25

6.4

54

13.8

9d

Over 5,000

2

0

0

0

0

0

0

0

0

1

50.0

0

0

0

0

Grand total

393

78

19.8

65

16.5

100

25.4

9

2.3

161

41.0

25

6.4

54

13.7

aIncludes necrotic gingivitis (within 39 days).

bIncludes bloody diarrhea.

cIncludes people indoors, type of building unknown.

dThere is no ring 8 in the Joint Commission system of designating distance.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

concluded that while the experience of the Joint Commission left no doubt as to the desirability of collecting shielding data, this should be simple in nature.

4.4 The type of radiation data collected in this study.—In addition to the biological considerations which we have just discussed, certain “practical” considerations entered into the determination of the type of data to be collected. The histories were to be obtained by clerks with the equivalent of a high school education. These clerks, although they could be carefully drilled in their duties, could not be expected to exercise a great deal of judgment if the approach to the problem involved the compilation of an elaborate history. It could be anticipated that the turn-over among clerks would be rather high. Finally, since the history taking was to extend over an indefinite number of years, much was to be said for concentrating on certain salient features of the individual's experience, which could be as readily recalled relatively late as relatively early.

With all these considerations in mind, the

TABLE 4.3 DISTRIBUTIONBY DISTANCEAND SHIELDINGOFHUSBANDSOF WIVES REGISTERING PREGNANCIESWITHTHE GENETICS PROGRAM (HIROSHIMA) (For a definition of the classes see Sec. 4.5.)

Distance (hundreds of meters)

No. persons symptomatic

Pa

Ga

Ea

PG

PE

GE

PGE

No. persons asymptomatic

Total no. persons exposed (a)

Total no. symptoms experienced (b)

Ratio (b/a)

In open

 

00–04

1

1

2

3

3

05–09

15

1

6

1

2

5

12

27

28

1.04

10–14

53

4

3

22

3

9

12

102

155

89

.57

15–19

44

5

6

23

2

3

3

2

287

331

56

.17

20–24

29

4

6

12

1

2

4

409

438

36

.08

25–29

11

4

4

1

2

213

224

14

.06

30+

17

1

7

5

2

2

868

885

21

.02

 

1,893

2,063

 

In Japanese building

 

00–04

2

2

1

3

6

05–09

39

1

1

8

4

9

16

13

52

84

1.62

10–14

127

11

8

29

10

16

14

39

387

514

245

.48

15–19

54

20

11

10

3

4

4

2

695

749

69

.09

20–24

27

9

6

5

2

3

2

634

661

36

.05

25–29

11

2

1

2

1

2

2

1

444

455

18

.04

30+

24

5

3

10

1

4

1

1,636

1,660

31

.02

 

3,810

4,094

 

In other shelter

 

00–04

2

2

05–09

14

2

5

1

3

3

17

31

24

.77

10–14

17

6

4

1

1

1

2

2

33

50

25

.50

15–19

6

1

3

2

61

67

8

.12

20–24

2

1

1

46

48

2

.04

25–29

2

1

1

51

53

4

.08

30+

2

1

1

200

202

2

.01

 

410

453

 

aP=Petechiae; G=Gingivitis; E=Epilation.

following information was obtained concerning each pregnant woman and her spouse included in this study:

  1. Presence in Hiroshima or Nagasaki at the time of the bombing.

  2. Location in city at time of bombing.

  3. Distance from the hypocenter [calculated from (2)].

  4. Indoors or outdoors.

  5. Type of building.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
  1. Occurrence of subcutaneous bleeding (petechiae).

  2. Occurrence of gingivitis.

  3. Occurrence of bloody diarrhea.

  4. Occurrence of epilation (partial or complete).

  5. Occurrence of burns.

  6. Occurrence of external injuries.

TABLE 4.4 DISTRIBUTIONBY DISTANCEAND SHIELDINGOFWIVES REGISTERING PREGNANCIESWITHTHE GENETICS PROGRAM (HIROSHIMA)

Distance (hundreds of meters)

No. persons symptomatic

Pa

Ga

Ea

PG

PE

GE

PGE

No. persons asymptomatic

Total no. persons exposed (a)

Total no. symptoms experienced (b)

Ratio (b/a)

In open

 

00–04

1

1

05–09

14

4

1

6

3

8

22

27

1.23

10–14

75

9

2

24

1

8

13

18

156

231

133

.58

15–19

85

10

9

50

3

4

3

6

489

574

107

.19

20–24

53

7

6

26

1

8

5

560

613

72

.12

25–29

18

7

3

4

2

2

311

329

24

.07

30+

24

2

6

11

1

4

1,020

1,044

29

.03

 

2,545

2,814

 

In Japanese building

 

00–04

2

2

1

3

6

05–09

52

1

1

7

2

15

6

20

23

75

115

1.53

10–14

254

41

17

66

8

38

23

61

881

1,135

445

.39

15–19

116

36

24

36

1

8

4

7

1,668

1,784

143

.08

20–24

65

18

13

22

1

6

1

4

1,398

1,463

81

.06

25–29

28

13

4

6

2

2

1

1,205

1,233

33

.03

30+

31

9

11

8

2

1

3,369

3,400

34

.01

 

8,545

9,093

 

In other shelter

 

00–04

3

1

2

3

5

05–09

35

3

5

1

8

6

12

75

110

74

.67

10–14

13

3

2

1

2

1

2

2

102

115

22

.19

15–19

11

3

6

1

1

181

192

13

.07

20–24

8

5

1

2

117

125

8

.06

25–29

1

1

148

149

1

.01

30+

3

1

1

1

188

191

4

.02

 

811

885

 

aP=Petechiae; G=Gingivitis; E=Epilation.

In locating the position of an individual at the time of the bombing an effort was made to pinpoint position as accurately as possible. The distance from the hypocenter was then determined by actual measurement on a large-scale map of the city. The method of measurement has varied from time to time, involving variously the use of plastic and metal tapes, coordinates, and concentric circles. In the process of calculation, meters are rounded to decameters, and decameters further rounded to hectometers, so that the coded interval in hectometers denotes (x-55) to (x+44) meters.

Items 4 and 5 on the above list represent an attempt, however rough, to accumulate certain data relative to the evaluation of shielding. Item 4 was to be answered simply as indoors or outdoors. Item 5 pursued the point somewhat further, admitting of ten alternatives, namely, if indoors, then

  1. Inside concrete building,

  2. Inside brick building,

  3. Inside wooden Japanese or other type building,

  4. Inside cave or “bunker,”

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

and if outdoors, then

  1. In open,

  2. Behind (within two meters) wall,

  3. In trench,

  4. Behind post or tree,

  5. In tram, train, or car, and

  6. Under eaves of house (i.e., shielded by house).

TABLE 4.5 DISTRIBUTIONBY DISTANCEAND SHIELDINGOFHUSBANDSOF WIVES REGISTERING PREGNANCIESWITHTHE GENETICS PROGRAM (NAGASAKI)

Distance (hundreds of meters)

No. persons symptomatic

Pa

Ga

Ea

PG

PE

GE

PGE

No. persons asymptomatic

Total no. persons exposed (a)

Total no. symptoms experienced (b)

Ratio (b/a)

In open

 

00–04

1

1

05–09

5

1

1

1

2

6

11

9

.82

10–14

20

3

2

10

3

2

51

71

27

.38

15–19

11

2

5

1

1

2

72

83

17

.20

20–24

4

1

1

2

94

98

4

.04

25–29

7

2

1

4

165

172

7

.04

30+

8

3

4

1

1,151

1,159

10

.01

 

1,540

1,595

 

In Japanese building

 

00–04

1

1

05–09

6

1

1

2

2

10

16

13

.81

10–14

45

6

6

9

3

7

2

12

186

231

81

.35

15–19

23

2

5

9

1

2

2

2

216

239

32

.13

20–24

2

2

220

222

2

.01

25–29

2

1

1

387

389

2

.005

30+

11

4

2

3

2

2,714

2,725

13

.005

 

3,734

3,823

 

In other shelter

 

00–04

1

1

05–09

10

1

1

3

2

3

34

44

18

.41

10–14

43

5

4

10

5

4

6

9

188

231

76

.33

15–19

14

3

4

1

2

1

3

171

185

24

.13

20–24

2

1

1

103

105

2

.02

25–29

2

1

1

101

103

3

.03

30+

4

2

1

1

1,560

1,564

4

.003

 

2,158

2,233

 

aP=Petechiae; G=Gingivitis; E=Epilation.

Items 6–9, bearing on radiation sickness, were to be answered simply as “yes” or “no,” after a brief explanation of the symptom by the clerk, if necessary. Limiting answers to “yes” or “no” obviously required the clerk to exercise her judgment in some cases. For the more vague term “oropharyngeal lesions” we have substituted gingivitis, since a necrotic-type of gingivitis with gingival bleeding was one of the more prominent and specific of the oropharyngeal lesions.

In the original design of the study, no symptom among those listed was to be recognized unless it developed prior to December 15, 1945. Some instances have come to light where the alleged onset of symptoms after that date have been recorded. This cannot be attributed to exposure to the bomb. There is a good reason to believe that the erroneous inclusion of such reports of “delayed effects” occurred very rarely.

Items 10 and 11 were included as one of several approaches to the problem of disentangling the possible radiation effects of the bombs from other effects and also the general disaster effect. Thus, it was anticipated that in the event of a positive correlation between some aspect of pregnancy termination and radiation history, an attempt could be made to determine if the correlation still held up after the elimina-

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

tion of those recording burns or external injuries of any type.

Those familiar with the problem of evaluating radiation exposure will be quick to recognize the very simple nature of the data collected in this study. The adequacy of these data as a basis for quantitative estimates of irradiation has been the subject of considerable discussion. Specifically, the possible desirability of a much more elaborate history was repeatedly discussed. It is our contention, admittedly subjective but documented in part by the internal consistency of the data presented in the following sections, the recall factor in these situations being what it is, and in view of the radiation variables, that this represents the most practical approach to this problem which could be adopted.

TABLE 4.6 DISTRIBUTIONBY DISTANCEAND SHIELDINGOFWIVES REGISTERING PREGNANCIESWITHTHE GENETICS PROGRAM (NAGASAKI)

Distance (hundreds of meters)

No. persons symptomatic

Pa

Ga

Ea

PG

PE

GE

PGE

No. persons asymptomatic

Total no. persons exposed (a)

Total no. symptoms experienced (b)

Ratio (b/a)

In open

 

00–04

1

05–09

5

2

2

1

7

12

9

.75

10–14

24

3

2

7

1

2

3

6

60

84

42

.50

15–19

18

2

2

9

2

1

2

108

126

25

.20

20–24

7

5

2

173

180

9

.05

25–29

9

1

1

5

2

274

283

11

.04

30+

10

2

3

4

1

1,674

1,684

11

.01

 

2,297

2,369

 

In Japanese building

 

00–04

05–09

4

1

1

2

7

11

9

.82

10–14

129

11

7

35

7

15

22

32

292

421

237

.56

15–19

55

12

6

19

1

6

6

5

459

514

78

.15

20–24

26

5

9

9

1

1

1

842

868

29

.03

25–29

6

2

3

1

1,106

1,112

7

.006

30+

19

7

5

6

1

7,162

7,181

20

.003

 

9,868

10,107

 

In other shelter

 

00–04

5

05–09

19

1

2

9

1

1

4

1

74

93

27

.29

10–14

56

3

6

24

4

5

7

7

185

241

86

.36

15–19

25

6

1

11

1

6

109

134

38

.28

20–24

9

2

3

3

1

145

154

11

.07

25–29

5

1

2

1

1

154

159

6

.04

30+

7

1

3

2

1

2,005

2,012

8

.004

 

2,677

2,793

 

aP=Petechiae; G=Gingivitis; E=Epilation.

4.5 The relation between distance, shielding, and symptoms in these data.— Tables 4.3 to 4.6 summarize the findings of the present study as regards the relationship between certain types of shielding, certain symptoms, and distance from the hypocenter. Based on items of the questionnaire (see preceding section), two degrees of shielding have been recognized, namely, that provided by being inside a Japanese-type home at the time of the explosion, and that provided by being inside any other type of structure—concrete or brick building, cave or bunker-type air raid shelter. Figures 4.1 and 4.2 present these same findings in graphic form. For ease of presentation, a “symptom ratio” has been used, consisting of the total number of symptoms (epilation, petechiae, or gingivitis) recorded by the survivors at a particular distance, divided by the number of survivors giving information. Data are not plotted for the 00–04 distances because of the few individuals in-

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

volved. Several important conclusions emerge from a consideration of these data:

4.5.1 For all three groups, the symptom ratio falls off rapidly with distance. In the light of these findings, as well as the distance-dosage relationship estimated on physical grounds (see below), it seems unlikely that there was significant radiation beyond 3,000 meters from the hypocenter. The few individuals reporting epilation, petechiae, and/or gingivitis beyond that distance are, with possible rare exceptions, almost certainly in error in attributing their symptoms to irradiation. Taking this 1–2 per cent as a baseline for “false reporting,” it follows that the symptomatic group within 3,000 meters may also be somewhat “diluted” by false reporting.

FIGURE 4.1—Symptom ratio in relation to distance from hypocenter for Hiroshima (husbands and wives combined). Explanation in text.

4.5.2 There is evidence that shielding in “other style” buildings substantially reduced the proportion of persons with symptoms at distances within 1,500 meters.

4.5.3 In what appears at first sight to be a paradox, in the 500–900 meter ring a substantially higher proportion of persons in Japanese homes developed symptoms than did persons in the open. The reason for this seems clear. At this distance, persons reporting themselves in the open must actually have been shielded by one or more buildings from the bomb burst, otherwise they almost certainly

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

would have sustained fatal burns. The biological evidence suggests that the total average shielding of such persons actually exceeded that of persons in Japanese homes.

4.5.4 In the 1,000–1,900 meter ring, there is a suggestion that in Hiroshima, although not so clearly in Nagasaki, presence in a Japanese-style home conferred some protection against the development of symptoms, the basis for comparison being persons reporting themselves “outdoors.” The average amount of shielding by which a person “in the open” was protected is very difficult to estimate. It is somewhat easier to quantitate the shielding of the persons in Japanese-style buildings. Woodbury (1953 and unpublished) reports that X-ray photographs taken at 62-kv indicate that the absorption of the bamboo-lattice and mud walls of the average Japanese house is equal to about 33 mm. of aluminum in the densest portion, and 15 mm. in the lightest. The absorptive value of the tile roofs which are standard construction in Japanese houses is undoubtedly more variable, depending on the distance from the hypocenter and the consequent variation in the angle of incidence of the radiation. However, for radiation incident at right angles, the average tile roof has an absorptive value in the neighborhood of 45 mm. of aluminum. Beyond 1,000 meters, persons in Japanese-type buildings in Hiroshima at the time of the explosion probably averaged several such walls or roofs between themselves and the exploding bomb. This is a significant degree of shielding. In very round terms, such shielding would screen out in the neighborhood of 50 per cent of the dosage at a level of 100r of the high-energy X-ray and gamma radiation released by the bomb.

FIGURE 4.2—Symptom ratio in relation to distance from hypocenter for Nagasaki (husbands and wives combined). Explanation in text.

It seems worth pointing out that the amount of shielding implied in the statement, “in a Japanese-style home,” varies directly with distance from hypocenter, since at greater distances, because of the angle of incidence of the radiation, more walls and roofs would usually intervene between the source of radiation than at lesser distances. Persons in Nagasaki in Japanese homes at the time of the explosion on the average were probably less shielded than in

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Hiroshima, because of the difference in terrain and the extension of homes up the sides of the valley.

4.6 Factors contributing to the validity of the radiation histories.— The value of several different persons obtaining a history from a given individual is well known in clinical medicine. The changes in emphasis and the new material introduced, as the patient passes from one interviewer to the next, are sometimes remarkable. From the standpoint of verifying information, the Genetics Program has been fortunate for the following reasons:

4.6.1 Over the 6-year span covered by this program, many women registered two or more times (cf. Sec. 5.6). At each registration, a history was obtained without reference to any previous history.

4.6.2 In 1950 a Radiation Census was carried out in both Hiroshima and Nagasaki. This census obtained brief data on each survivor of the bombings then living in Hiroshima and Nagasaki, including position at the time of the bombing.

4.6.3 Some of the parents falling within the scope of the Genetics Program—especially the more heavily irradiated—also came under scrutiny in connection with other special studies of the ABCC, such as the Adult Medical Program, the Ophthalmology Program, etc. Each of these latter programs obtained a very detailed radiation history.

All of the information available on any given person was correlated through a Master File. Particular attention was directed towards a comparison of the radiation histories obtained from a given person on different occasions. In the event of a discrepancy, an effort was made to query the individual concerned, in an attempt to resolve it. On the basis of the information obtained on the query, a single uniform entry was made on all the forms involved. As might be expected, changes on the Genetics Short Form were not infrequent, although the data have not been kept in such a fashion as to permit a precise analysis. However, it is our impression that important changes were not common.

4.7 Definition of radiation categories.—We are now in a position to define certain “radiation categories” which will be basic to the analysis which follows. This is done in Table 4.7. “Heavy” shielding denotes presence in concrete or brick building or air raid shelter at the time of the explosion. “Moderate” shielding includes being within a street car, train, or car, behind a wall or under the eaves of a house, i.e., on the side of the house away from the hypocenter. Finally, “light” shielding includes those giving their location as in a Japanese-style building or in a trench or behind a post or tree. Trench-type shielding is classified as “light” because of the difficulty in establishing how well an individual was protected by a trench.

TABLE 4.7 THE DEFINITIONOF “EXPOSURE CATEGORIESTOBE EMPLOYEDINTHIS ANALYSIS

 

Groups

 
 

1

2

3

4

5

Unexposed

+

Over 3,000 meters, with or without alleged

 

symptoms

+

2,000–2,900 meters

 

Heavy shielding

+

Moderate shielding

+

Light shielding

+

No shielding

+

1,500–1,900 meters

 

Heavy shielding

+

Moderate shielding

+

Light shielding

+

No shielding

+

1,000–1,400 meters

 

Heavy shielding

+

Moderate shielding

+

Light shielding

+

No shielding

+

Under 1,000 meters

 

Heavy shielding

+

Moderate shielding

+

Light shielding

+

No shielding

+

Symptoms (epilation, petechiae, gingivitis), un

 

der 3,000 meters

+

Inspection of Table 4.7 in the light of the preceding discussion suggests that this is a somewhat “conservative” classification, in terms of correction for shielding. Thus, individuals reporting “heavy” shielding but asymptomatic have all been relegated to group 2, despite the fact that the symptom ratio in heavily shielded persons within 1,000 meters is approximately 0.7. Since relatively few persons were “heavily” shielded (see below), the net effect of this will be to increase slightly the average radiation dosage of group 2. On the other hand, this removes from categories 3 and 4, which received intermediate amounts of radiation, a group of

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

individuals whose average radiation dose would be extremely difficult to evaluate.

The distribution of all the parents of registered terminations included in this study in terms of their radiation category is given in Table 4.8. Approximately 78.3 per cent of all the fathers who were registered, and 57.0 per cent of all the mothers, were not in the cities at all at the time of the explosion. Of those present in the cities, a substantial majority was beyond 3,000 meters from the hypocenter. Only 1.2 per cent of fathers, and 2.4 per cent of mothers, reported symptoms characteristic of radiation sickness.

In a preliminary report on this study (Neel et al., 1953), a system of radiation categories was employed which failed to take into account shielding. Thus, in this treatment group 4 was defined simply as: “In one of the two cities, and less than 1,845 meters from the hypocenter, but asymptomatic. Most of these individuals were shielded to a greater or lesser extent from the full effects of the bombs.” In this preliminary treatment, for some purposes the offspring of parents both of whom were group 4 or 5 were considered. In the case of the malformation analysis, for example, there were available 596 infants born to parents meeting these restrictions. But with the radiation categories which have just been defined, there are in the malformation analysis ( Table 8.4) only 145 infants born to parents both in categories 4 or 5. The difference in numbers is due almost entirely to the attempt to correct for shielding.

TABLE 4.8 DISTRIBUTIONOF REGISTERED BIRTHSBY PARENTAL EXPOSURE

 

Hiroshima

Nagasaki

 
 

Mother's exposure

 

Mother's exposure

 
 
 
 
 

1

2

3

4

5

Total

1

2

3

4

5

Total

1

18,723

5,721

2,320

417

791

27,972

16,338

10,141

823

116

480

27,898

2

1,611

1,993

451

90

127

4,272

2,420

4,483

298

38

91

7,330

3

648

416

545

49

67

1,725

258

301

109

14

21

703

4

147

119

81

28

26

401

42

55

14

5

1

117

5

275

145

80

19

54

573

107

133

25

3

21

289

 

Total

21,404

8,394

3,477

603

1,065

34,943

19,165

15,113

1,269

176

614

36,337

4.8 Considerations in the estimation of the average amount of radiation received by persons in each of the five radiation categories.—We come now to an attempt to estimate the average amount of radiation represented by each of the five radiation categories. It should at once be made clear that with the possible exceptions of categories 1 and 5, any estimate is at best an exceedingly rough approximation. For categories 2, 3, and 4, we will do well if we establish the range within which the true average is likely to be found. A particular difficulty in estimating radiation dosage, already alluded to, is the fact that a wide spectrum of radiant energy is involved, with the consequent complications in expressing tissue dosage in simple terms, a difficulty only partially circumvented by expressing dosage in terms of the “roentgen equivalent physical” (rep) unit. This latter may be defined as that amount of any ionizing radiation (beta rays, neutrons, etc.) which dissipates the same amount of energy per gram of water as one roentgen of X-rays or gamma rays. All estimates refer to surface dose. The actual amount of irradiation delivered to the gonad will be less, although because of the high energy content of atomic bomb irradiation, the gonad dose will actually be rather close to the skin dose.

Category 1 individuals, outside the cities at the time of the bombing, of course have received no radiation from the atomic bomb (ignoring, of course, the possibility of residual radiation). Category 5 individuals, symptomatic and within 3,000 meters, are considered to have received as a minimum the equivalent of 200 roentgens of gamma rays (Los Alamos Scientific Laboratory, 1950). The maximum dose received by a category 5 individual is in the neighborhood of the equivalent of 600 roentgens of gamma rays. The latter figure is based on the premise that the LD50 in man for whole-body radiation is about 400 roentgens of gamma rays, but that a few individuals may survive doses amounting to 600r of gamma rays (Hempelmann, Lisco, and Hoffman, 1952). The average dose received by category 5 individuals can probably be placed at the equivalent of 300–400 roentgens of

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

gamma rays. We will return shortly to the important question of the magnitude of the neutron component of this estimated dosage. Suffice it to say at this point that category 5 persons as a group received a relatively larger amount of neutron radiation than any other group, and because of the relatively greater biological effectiveness of neutrons as contrasted to gamma rays, generally speaking, the dose in rep units received by category 5 persons may be substantially below the dose as expressed in roentgens.

FIGURE 4.3—Total dosage of initial gamma radiation as a function of distance from the hypocenter of the explosion of a “nominal” atomic bomb, from “The Effects of Atomic Weapons.”

In arriving at our estimate of the amount of radiation received by category 2, 3, and 4 individuals, three considerations are outstanding:

4.8.1 The estimated distance-dosage curve. —Figures 4.3 and 4.4 are the distance-dosage curves in terms of neutron and gamma radiation for the explosion of a “nominal” atomic bomb, roughly comparable to what was detonated over Hiroshima and Nagasaki, as published in “The Effects of Atomic Weapons.” In the absence of other unclassified data, this must of necessity serve as the only guide available. Note that the abscissa in both figures is scaled in terms of feet rather than the meters in which we have expressed distance. Figure 4.3, if taken at face value, indicates that beyond approximately 1,600 meters the amount of gamma radiation received was less than 100r. Our own observations, involving the reported appearance of symptoms in, e.g., significant numbers of persons in the 2,000–2,400 meter ring, lead us to feel this estimate is somewhat conservative. Also, unpublished calculations of Wilson (1951) suggest that, at least for Hiroshima, the neutron curve given in Figure 4.4 is on the conservative side. On the other hand, both from these two curves and on the basis of our own observations regarding the shape of the distance-dosage curve, it seems likely that persons at distances in excess of 3,000 meters received little if any radiation.

FIGURE 4.4—Fast and slow neutrons delivered per square centimeter as a function of distance from the hypocenter of the explosion of a “nominal” atomic bomb, from “The Effects of Atomic Weapons.”

4.8.2 The observations of the Joint Commission regarding leucopenia.—One of the well recognized effects of whole-body irradiation in amounts compatible with survival is a temporary leucopenia. Information concerning the proportion of individuals in the radiation categories defined above who developed leucopenia following their exposure would therefore be of value in any attempt to estimate radiation

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

dosage. Certain of the published observations of the Joint Commission are quite useful in this respect. The more pertinent portion of their published data is summarized in Table 4.9 (see also LeRoy, 1950). Leucopenia is here defined as a total leucocyte count per mm.3 of less than 3,000 at some time during the second through the fifth weeks following the bombing. Some of the individuals on whom the percentages in Table 4.9 are based had repeated leucocyte determinations during a hospitalization, others had but a single count, at any time between the second and fifth weeks. The figures are thus at best estimates of the percentage which on careful studies would be found to develop leucopenia. The exposure categories utilized by the Joint Commission and reproduced in Table 4.9 are somewhat different from our own, the four most severe, the ones with which we are concerned, being defined as shown in Table 4.10.

TABLE 4.9 THE FINDINGSOF THE JOINT COMMISSIONIN HIROSHIMAWITH REGARDTO THE OCCURRENCEOF EPILATION, PETECHIAE, AND LEUCOPENIAIN PERSONS FALLINGINTO VARIOUS EXPOSURE CATEGORIES (Further explanation in text.)

 

Exposure category

 
 

A

B

C

D

Epilation

 

No. examined

570

1,119

1,817

1,604

No. epilated

434

400

172

74

% epilated

76.1

35.7

9.5

4.6

Petechiae

 

No. examined

570

1,119

1,817

1,604

No. with petechiae

310

262

108

31

% with petechiae

54.4

23.4

5.9

1.9

Leucopenia

 

No. examined

195

211

156

111

No. with leucopenia

146

121

31

10

% with leucopenia

74.9

57.3

19.9

9.0

It will be noted that the figures regarding leucopenia are based on fewer individuals than those with respect to epilation and petechiae. This is understandable in view of the difficulties in obtaining leucocyte determinations imposed by the conditions prevailing following the bombing. As the Commission report points out, these figures must be accepted with some reservations in view of the unfavorable circumstances under which they were obtained; on the other hand, the manner in which the findings regarding leucopenia parallel those on petechiae and epilation gives indirect confirmation of their validity. Since the Commission worked with a selected sample, composed largely of injured and, in the majority of cases, hospitalized survivors, caution must be exercised in extrapolating to our own, total sample. It will be noted, however, that with the exception of exposure category A, more of the persons examined developed leucopenia than either epilation or petechiae.

TABLE 4.10 THE EXPOSURE CATEGORIES DEFINEDBY THE JOINT COMMISSION, TO BE APPLIEDTO THE INTERPRETATIONOF TABLE 4.9

 

Exposure group

 

Description

A

B

C

D

E

F

0–1,000 meters

 

Outdoors or in Japanese buildings

+

In heavy buildings

+

In bomb shelters

+

1,100–1,500 meters

 

Outdoors or in Japanese buildings

+

In heavy buildings

+

In bomb shelters

+

1,600–2,000 meters

 

Outdoors or in Japanese buildings

+

In heavy buildings

+

In bomb shelters

+

2,100–2,500 meters

 

Outdoors or in Japanese buildings

+

In heavy buildings

+

In bomb shelters

+

2,600–3,000 meters

 

Outdoors or in Japanese buildings

+

In heavy buildings

+

In bomb shelters

Through the courtesy of The Armed Forces Institute of Pathology, it has been possible to obtain certain very useful additional tabulations of the material collected by the Joint Commission. Among exposed Japanese in Hiroshima who received one or more leucocyte determinations sometime between the second and fourteenth weeks, who failed to develop epilation, petechiae, or gingivitis, and who are not known to have died within the fourteen weeks following the bombings, the distribution of lowest observed leucocyte counts by distance is as shown in Table 4.11. More intensive studies would have shown a higher proportion with leucopenia.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

TABLE 4.11 THE DISTRIBUTIONOF LEUCOCYTE VALUESIN HIROSHIMA JAPANESE WHO FAILEDTO DEVELOP EPILATION, PETECHIAE, OR GINGIVITIS FOLLOWINGTHE BOMBING, IN RELATIONTO DISTANCEFROM HYPOCENTERAND TYPEOF SHIELDING (Data of Joint Commission, as tabulated by the Armed Forces Institute of Pathology)

Distance from hypocenter less than 1,500 meters

 

Outdoors, unshielded

Outdoors, shielded

Indoors, Jap. bldg.

Indoors, heavy bldg. shelter

 

Leucocytes/mm.3

No.

Cum. %

No.

Cum. %

No.

Cum. %

No.

Cum. %

0–500

1

1.4

0

0

0

0

0

0

600–1,000

1

2.9

1

2.7

1

.5

0

0

1,100–1,500

1

4.3

1

5.4

2

1.6

1

1.0

1,600–2,000

0

4.3

1

8.1

6

4.9

3

4.1

2,100–2,500

1

5.7

2

13.5

6

8.2

1

5.2

2,600–3,000

1

7.1

1

16.2

9

13.0

1

6.2

3,100–3,500

3

11.4

1

18.9

16

21.7

3

9.3

3,600–4,000

5

18.6

2

24.3

22

33.7

7

16.5

4,100–4,500

7

28.6

6

40.5

11

39.7

0

16.5

4,600–5,000

5

35.7

3

48.6

14

47.3

1

17.5

5,100–5,500

3

40.0

3

56.8

16

56.0

18

36.1

5,600–6,000

6

48.6

9

81.1

9

60.9

7

43.3

6,100–6,500

8

60.0

3

89.2

16

69.6

11

54.6

6,600–7,000

7

70.0

0

89.2

15

77.7

8

62.9

7,100–7,500

2

72.9

0

89.2

8

82.1

4

67.0

7,600–8,000

4

78.6

2

94.6

7

85.9

8

75.3

8,100–8,500

2

81.4

0

94.6

9

90.8

3

78.4

8,600–9,000

5

88.6

1

97.3

3

92.4

7

85.6

9,100–9,500

1

90.0

1

100.0

2

93.5

2

87.6

9,600–

7

100.0

0

100.0

12

100.0

12

100.0

 

70

 

37

 

184

 

97

 

Distance from hypocenter 1,600–2,000 meters

 

Outdoors, unshielded

Outdoors, shielded

Indoors, Jap. bldg.

Indoors, heavy bldg. shelter

 

Leucocytes/mm.3

No.

Cum. %

No.

Cum. %

No.

Cum. %

No.

Cum.%

0–500

0

0

0

0

1

.4

0

0

600–1,000

0

0

0

0

0

.4

0

0

1,100–1,500

3

1.1

1

1.7

0

.4

1

1.9

1,600–2,000

1

1.5

0

1.7

2

1.1

0

1.9

2,100–2,500

3

2.6

0

1.7

5

3.0

1

3.7

2,600–3,000

5

4.5

1

3.4

4

4.5

0

3.7

3,100–3,500

11

8.6

4

10.2

10

8.2

1

5.6

3,600–4,000

16

14.7

2

13.6

16

14.1

2

9.3

4,100–4,500

17

21.1

6

23.7

26

23.8

6

20.4

4,600–5,000

10

24.8

1

25.4

17

30.1

1

22.2

5,100–5,500

30

36.1

8

39.0

23

38.7

6

33.3

5,600–6,000

18

42.9

11

57.6

27

48.7

8

48.1

6,100–6,500

22

51.1

5

66.1

17

55.0

4

55.6

6,600–7,000

26

60.9

2

69.5

27

65.1

2

59.3

7,100–7,500

14

66.2

3

74.6

21

72.9

3

64.8

7,600–8,000

21

74.1

3

79.7

14

78.1

3

70.4

8,100–8,500

9

77.4

3

84.7

16

84.0

4

77.8

8,600–9,000

21

85.3

3

89.8

11

88.1

8

92.6

9,100–9,500

9

88.7

2

93.2

8

91.1

1

94.4

9,600–

30

100.0

4

100.0

24

100.0

3

100.0

 

266

 

59

 

269

 

54

 
Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Distance from hypocenter 2,100–3,000 meters

 

Outdoors, unshielded

Outdoors, shielded

Indoors, Jap. bldg.

Indoors, heavy bldg. shelter

 

Leucocytes/mm.3

No.

Cum. %

No.

Cum. %

No.

Cum. %

No.

Cum. %

0–500

0

0

0

0

0

0

0

0

600–1,000

0

0

0

0

0

0

0

0

1,100–1,500

0

0

0

0

1

.2

0

0

1,600–2,000

0

0

0

0

2

.6

0

0

2,100–2,500

5

1.9

0

0

3

1.3

0

0

2,600–3,000

3

3.1

1

2.6

9

3.2

1

9.1

3,100–3,500

8

6.1

1

5.3

16

6.6

0

9.1

3,600–4,000

12

10.7

1

7.9

16

10.0

0

9.1

4,100–4,500

14

16.0

0

7.9

28

16.0

2

27.3

4,600–5,000

20

23.7

1

10.5

29

22.2

0

27.3

5,100–5,500

19

30.9

5

23.7

50

32.9

3

54.5

5,600–6,000

27

41.2

2

28.9

43

42.1

0

54.5

6,100–6,500

27

51.5

4

39.5

47

52.1

1

63.6

6,600–7,000

23

60.3

4

50.0

34

59.4

1

72.7

7,100–7,500

15

66.0

2

55.3

34

66.7

0

72.7

7,600–8,000

14

71.4

2

60.5

25

72.0

1

81.8

8,100–8,500

18

78.2

2

65.8

34

79.3

0

81.8

8,600–9,000

17

84.7

4

76.3

26

84.8

1

90.9

9,100–9,500

6

87.0

1

78.9

10

87.0

0

90.9

9,600–

34

100.0

8

100.0

61

100.0

1

100.0

 

262

 

38

 

468

 

11

 

The concentration of values in the “9,600 and above” class would seem to indicate a grouping of values which would vitiate attempts to calculate a mean. However, generally speaking, these observations suggest that a significant number of persons in our radiation categories 3 and 4 probably developed leucopenia as that term is here defined. An exact estimate of the proportion is difficult because of the difference between the way the Joint Commission's and our own data are broken down, but in round figures, based in part on the data in Table 4.11, it can be estimated that some 5–10 per cent of group 4 parents and 2–4 per cent of group 3 parents developed leucopenia.

The average amount of whole-body irradiation which, when delivered over a period of a day or two, will produce in man leucopenia of this degree is not known with certainty. For obvious reasons, there are not many pertinent observations. Thus, studies of patients with leukemia or multiple myeloma (e.g., Collins and Loeffler, 1956), while valuable for therapeutic reasons, obviously do not permit extrapolation to normal persons. Of the more recent investigations, the most valuable for present purposes—although still, because of the nature of the subjects, to be interpreted with caution— are those of Nickson (1951), who found that in three patients with carcinoma with metastases, 120r of whole-body irradiation with 400-kv X-rays produced no significant leucopenia. Two of these patients had a moderate leucocytosis at the time of treatment, amounting to 14,700/mm.3 and 13,900/mm.3, respectively. A fourth patient, also with carcinomatosis, who was treated with 107r of 200-kv whole-body X-rays on two successive days likewise failed to develop significant leucopenia. The impropriety of extrapolating from such patients to normal individuals is apparent. Furthermore, it does not appear that these patients were followed long enough for the detection of late leucopenic effects. The studies of Hempelmann, Lisco, and Hoffman (1952) on the few persons who have been involved in industrial radiation accidents are also especially pertinent. In one case, an individual was exposed to an amount of irradiation estimated as the equivalent of 186 roentgens of 80-kv X-rays and 10.7 roentgens of γ-rays, and in another case, to the estimated equivalent of 140r of 80-kv X-rays and 8.7r of γ-rays. In neither case did leucopenia as here defined develop.

In March of 1954 certain natives of the Marshall Islands and a lesser number of Ameri-

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

can military personnel were accidentally exposed to the fall-out of radioactive materials subsequent to the explosion of an experimental thermonuclear device. Detailed hematological studies were carried out on these individuals (Cronkite, Bond, and Dunham, in manuscript). Through the courtesy of Dr. E.P.Cronkite and Mr. Hyman Hechter, the original data on the Marshall Islanders regarding total leucocyte counts during a 10 to 70-day period following the exposure have been made available to us. There were two groups of Marshall Islanders involved, one group of 64 estimated to have received an average dose of 175r of whole-body, gamma radiation as measured in air, and a second group of 18 estimated to have received an average dose of 69r of gamma radiation as measured in air. The actual dose received by the Marshallese has been the subject of lively discussion. The observed maximum depression in the total leucocyte count occurred between days 39 and 51 following the exposure (counts were made every four days). On day 39, 3.1 per cent of the Group I Marshallese were found to have a leucopenia of 3,000 WBC/mm.3 or less; on day 43, 6.5 per cent; on day 47, 3.1 per cent; and on day 51, 0.0 per cent. None of the Group II natives showed a leucopenia of this degree during this period.

A comparison of these figures with the Japanese figures cited above is biased by the fact that the Marshall Island figures refer to the period of peak depression, whereas the Japanese data include a longer period of time. Nevertheless, the important fact emerges that in a group of healthy persons known with some accuracy to have received a dose of whole-body gamma irradiation of approximately 175r, the frequency of leucopenia was probably no greater than (if as great as) that occurring in the category 4 parents of this study. The obvious inference is that the average radiation dose experienced by category 4 parents is at least the equivalent of 200r of whole-body gamma radiation, with category 3 parents receiving a smaller average dose, but very likely one in the neighborhood of the equivalent of 100r of whole-body gamma radiation.

4.8.3 The proportion of individuals protected by various types of shielding.— The final consideration to be introduced into this attempt to approximate the average radiation exposure in the various categories is the proportion of individuals experiencing various types of shielding. Data are not available for the whole sample. However, in a special study carried out in 1953 on all parents falling in the 1,800–2,500 meter ring, a group especially critical to this study, the breakdown shown in Table 4.12 was observed for 4,515 Hiroshima parents and 2,083 Nagasaki parents. The important point which emerges is the relatively small proportion of persons classified as receiving heavy or moderate shielding. It will be recalled that in the radiation classification adopted here, the report of “heavy” or “moderate” shielding resulted in an individual being placed in a lower radiation category. The contribution of such individuals—whose shielding is especially difficult to evaluate—to the composition of any radiation category is small.

TABLE 4.12 PROPORTIONSOF PARENTS EXPOSEDINTHE 1,800–2,500 METER RING WHO REPORTED VARIOUS TYPESOF SHIELDING

Degree of shielding

Hiroshima

Nagasaki

Heavy

4.9

15.9

Moderate

2.5

3.0

Light

68.0

67.0

None

24.6

14.1

 

100.0

100.0

4.9 Estimates of the average amount of irradiation received by individuals in the various exposure categories.—We are now in a position to approximate the average amount of whole-body irradiation received by individuals in categories 2 through 5. Category 2 individuals, on the basis of the distance-dosage curve, probably received on the average no more than 5–10 roentgens equivalent physical (rep's). Category 3 survivors, on the same basis, as well as the known incidence of leucopenia and the shielding data, may be estimated on the average to have received 50–100 rep's. The estimation of the dosage in rep's for groups 4 and 5 is more difficult because, in contrast to groups 2 and 3, there is, on the basis of the distance-dosage curves and the occurrence of radiation cataracts in appreciable numbers of these survivors, a significant neutron component in the irradiation experienced by these persons. To make approximate allowance for this, we will express “the equivalent of 300–400 roentgens of gamma rays” suggested earlier as the average dose in category 5, as 200–300 rep's, and on the same grounds estimate the average dosage for cate-

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

gory 4 individuals as 100–150 rep's. The arbitrary nature of these estimates will be apparent to all students of radiobiology. Any one might well be off by a factor of 2. We feel that any attempt to be more specific cannot be justified. In arriving at what some will term overly conservative estimates, we have been influenced by the fact that traumatic and thermal injuries may in a significant proportion of persons have combined with ordinarily sublethal radiation effects in causing death, thus lowering the mean radiation dose expected in the various categories on radiological grounds alone. On the other hand, any allowance for residual irradiation would revise the dose upward.

FIGURE 4.5—Neutron and gamma radiation distance-dosage curves for the atomic bomb explosions at Hiroshima and Nagasaki.

There are at present no published data which permit making a realistic estimate of the contribution of fast and slow neutrons to the total radiation spectrum. This is unfortunate in view of the relatively high biological efficiency of neutrons in inducing genetic change (summary in Symposium: Some Biological Effects of Radiation from Nuclear Detonation, 1954). However, it is important to recognize that the average dosages estimated above include, in the case of category 4 and 5 persons, a component of high effectiveness in producing genetic change.

Even should the upper rather than the lower estimates of the average amount of radiation received by survivors prove correct, the fact is clear that in the terms of the radiation geneticist, these are small doses indeed. This was recognized from the outset. But despite the improbability of being able to detect induced genetic effects in this material, there was no doubt in the minds of those who considered the problem initially, at all echelons, that “this unique possibility for demonstrating genetic effects caused by atomic radiation should not be lost” (cf. p. 2).

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Note added in proof.—At the time this chapter was written, only the distance-dosage curves for a “nominal” atomic bomb had been published. However, since this manuscript went to press, distance-dosage curves, in terms of neutron and gamma radiation, have been declassified for both Hiroshima and Nagasaki. These are presented in Fig. 4.5. The gamma curves for the two cities are quite comparable, and correspond satisfactorily with those published earlier for the explosion of a “nominal” atomic bomb. However, it will be noted that the neutron curves for the two cities appear to differ significantly, with, at a given distance, rather more radiation of this type in Hiroshima than in Nagasaki. The curve for the latter city approximates that published earlier for the explosion of a “nominal” bomb. In view of the many uncertainties that enter into assigning mean dosages to our radiation exposure categories, it is not felt that these new data warrant a revision of the estimates given in this chapter. On the other hand, it is clear that there is a very strong neutron component in the radiation experienced by category 4 and 5 parents in Hiroshima, and in this connection, it will be recalled that approximately 68 per cent of all category 4 or 5 parents were from Hiroshima. In view of the high relative effectiveness of neutrons in inducing genetic change, the publication of these new curves has the effect of increasing the genetic significance to be attached to the observations herein to be reported.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

Chapter V

THE COMPARABILITY OF IRRADIATION SUBCLASSES

THE infants examined in Hiroshima and Nagasaki during the course of this study may be apportioned among 25 subclasses on the basis of the radiation exposure categories of their fathers and mothers, as these categories were defined in the preceding chapter. The crux of our problem is a comparison of the characteristics of the infants comprising these subclasses. As has been emphasized several times already, all of the indicators of possible genetic damage utilized in this investigation may also be influenced by a variety of other factors. It will be the purpose of this chapter to undertake a detailed comparison of the parents of the infants comprising these subclasses with respect to certain possible differences which might influence the outcome of pregnancy. Of the many possible differences which could be explored, we shall restrict ourselves to those which in our opinion are most pertinent to the problem at hand and for which we have more nearly satisfactory data.

In the comparisons which will be presented, usually no allowance has been made for the fact that because of repeated pregnancies the same couple may be represented more than once among the parentage of a subclass. The tests of significance that follow assume no duplicate registration and thus yield underestimates of the errors of differences. It might be pointed out that, in the main, we should underestimate variances in the parental population more than in the offspring population.

5.1 Consanguinity.—It is generally recognized that the offspring of consanguineous marriages more often exhibit the consequences of genetic homozygosity than do the offspring of non-consanguineous unions. To the extent that there is a recessive, incompletely recessive, or semi-dominant genetic component in the etiology of congenital defect, stillbirth, or neonatal death, such homozygosity might be expected to alter the frequency of these events sufficiently to obscure real irradiation differences or to create spurious ones. The occurrence within the populations under study of a nonrandom distribution of consanguineous marriages thus might introduce a source of bias into the findings. This, then, was the theoretical consideration which led to the inclusion of an item in the Genetics Short Form regarding parental consanguinity. The problem seemed of special importance because of the relatively high frequency of consanguineous unions in Japan (Neel, Kodani, Brewer, and Anderson, 1949).

In Tables 5.1 and 5.2 the present data are examined as regards a relationship between exposure subclass and the frequency of consanguinity.1 Although all known degrees of consanguinity were recorded by the clerks, in the analysis attention has been restricted to marriages of first cousins, first cousins once removed, and second cousins. A few uncle-niece unions, and some involving more remote degrees of consanguinity than second cousin marriages, have been recorded during the study; all such unions have been excluded from these considerations because of the uncertainty regarding the exhaustiveness of the ascertainment.

There is significantly more consanguineous marriage in Nagasaki than in Hiroshima, this presumably a reflection of social and cultural differences between the two localities. Moreover, within the cities there is heterogeneity among exposure subclasses. In general this consists in less consanguineous marriage among the “exposed” (categories 2, 3, 4, 5) than among the

1  

The differing forms utilized in the presentation of the results of the analysis of the various tables will be evident following the reading of Chapter VI.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×
"http://www.w3.org/TR/2000/REC-xhtml1-20000126/DTD/xhtml1-transitional.dtd">

TABLE 5.1 CONSANGUINITY (FIRST COUSIN, FIRST COUSIN ONCE REMOVED, SECOND COUSIN) BY CITYAND PARENTAL EXPOSURE

Hiroshima

 

Fathersa

 
 

1

2

3

4–5

Total

1

n

18,723

1,611

648

422

21,404

r

1,242

97

42

23

1,404

p

.0663

.0602

.0648

.0545

.0656

2

n

5,721

1,993

416

264

8,394

r

311

117

27

16

471

p

.0544

.0587

.0649

.0606

.0561

3

n

2,320

451

545

161

3,477

r

97

23

16

4

140

p

.0418

.0510

.0294

.0248

.0403

4–5

n

1,208

217

116

127

1,668

r

77

9

6

6

98

p

.0637

.0415

.0517

.0472

.0588

Total

n

27,972

4,272

1,725

974

34,943

r

1,727

246

91

49

2,113

p

.0617

.0576

.0528

.0503

.0605

Nagasaki

 

Fathersa

 
 

1

2

3

4–5

Total

1

n

16,338

2,420

258

149

19,165

r

1,541

211

13

8

1,773

p

.0943

.0872

.0504

.0537

.0925

2

n

10,141

4,483

301

188

15,113

r

683

293

22

10

1,008

p

.0674

.0654

.0731

.0532

.0667

3

n

823

298

109

39

1,269

r

69

14

7

4

94

p

.0838

.0470

.0642

.1026

.0741

4–5

n

596

129

35

30

790

r

33

10

2

45

p

.0554

.0775

.0667

.0570

Total

n

27,898

7,330

703

406

36,337

r

2,326

528

42

24

2,920

p

.0834

.0720

.0597

.0591

.0804

aIn this and subsequent tables, the term “Fathers” will be used as an abbreviation for Father's Exposure Category, and the term “Mothers” similarly.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

unexposed (category 1), although the tendency is statistically significant only with respect to the mothers. There is also a significant city-mother interaction. Category 1 contains a high proportion of persons who did not legally reside in either of the two cities at the time of the bombings. It may be surmised that a substantial proportion of these persons have rural antecedents; the frequency of consanguinity is known to be higher in rural communities (Neel et al., 1949).

TABLE 5.2 CHI-SQUARE ANALYSISOFTHE FREQUENCYOF CONSANGUINEOUS MARRIAGESBY CITYAND PARENTAL EXPOSURE

Source

DF

X2

P

Total

31

261.453

<.001

Interactions, first order

 

CM

3

16.913

<.001

CF

3

1.610

.50–.70

MF

9

6.317

.70–.80

Main Effects

 

Citya

 

Mother's exposure—1

1

101.499

<.001

Mother's exposure—2

1

10.257

.001–.01

Mother's exposure—3

1

22.672

<.001

Mother's exposure—4, 5

1

0.031

.80–.90

Motherb

 

Hiroshima (H)

3

37.775

<.001

Nagasaki (N)

3

83.002

<.001

Fatherc

 

(H) Mother's exposure—1

3

1.783

.50–.70

Mother's exposure—2

3

1.292

.70–.80

Mother's exposure—3

3

4.156

.20–.30

Mother's exposure—4, 5

3

2.123

.50–.70

(N) Mother's exposure—1

3

9.581

.02–.05

Mother's exposure—2

3

0.947

.80–.90

Mother's exposure—3

3

4.950

.10–.20

Mother's exposure—4, 5

3

3.210

.30–.50

Sum

24

28.042

.20–.30

aAdjusted for mothers. (The meaning of the term “adjusted” is explained in Sec. 6.5.)

bAdjusted for cities.

cAdjusted for cities and mothers.

In Nagasaki, the bomb was detonated over that area of the city in which there was the highest concentration of Christians; Schull (1953) has shown that there is less consanguineous marriage among Christian (Catholic) Japanese in Nagasaki than among non-Christians. Thus, it may be surmised that among the non-Christian Japanese, the differences in frequency of consanguineous unions between Hiroshima and Nagasaki are even more striking than shown in Table 5.1.

5.2 Age and parity.—A probable or certain relationship between the correlated variables, parental age2 and parity,3 and most of the indicators of possible genetic damage herein studied is attested to by a voluminous literature (e.g., Ciocco, 1938; Yerushalmy, 1938; Penrose, 1939; Murphy, 1947; Landtman, 1948; Record and McKeown, 1949; Sutherland, 1949; Carter, 1950; Lowe and McKeown, 1950; Worcester, Stevenson, and Rice, 1950; Hegnauer, 1951; Karn and Penrose, 1951; Novitski, 1953; Salber and Bradshaw, 1953; MacMahon and Gordon, 1953; Myers, 1954). Our own analysis of these relationships in the present data will be published elsewhere. Suffice it to say at this point that significant associations can be readily demonstrated.

The findings in these data with respect to mean maternal age and parity differences among the mothers of the children falling into the various subclasses are shown in Tables 5.3

2  

The terms “parental age,” “maternal age,” or “paternal age” as here used refer simply to age of parent(s) at birth of child.

3  

The term “parity” refers simply to total number of conceptions, including the present.

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

TABLE 5.3 MEAN MATERNAL AGEBY CITYAND PARENTAL EXPOSURE (Based on unrelated parents only)

Hiroshima

 

Fathers

 
 

1

2

3

4

5

Total

1

n

17,481

1,514

606

136

263

20,000

27.0469

27.3250

27.5165

27.4853

28.2700

27.1013

2

n

5,410

1,876

389

108

140

7,923

26.8366

30.1311

29.2956

28.0926

28.7500

27.7883

3

n

2,223

428

529

81

76

3,337

26.9523

29.1402

30.9981

30.0123

29.0395

27.9961

4

n

388

88

45

24

19

564

27.7861

28.3636

29.6667

31.1667

29.6842

28.2340

5

n

743

120

65

26

52

1,006

27.1252

29.3667

29.3385

28.5385

31.4808

27.7972

Total

n

26,245

4,026

1,634

375

550

32,830

27.0087

28.9091

29.1989

28.5147

28.8509

27.3988

Nagasaki

 

Fathers

 
 

1

2

3

4

5

Total

1

n

14,797

2,209

245

41

100

17,392

28.5427

29.1421

29.5265

28.4878

30.2800

28.6425

2

n

9,458

4,190

279

51

127

14,105

27.6087

30.8477

30.3118

30.1176

29.8976

28.6540

3

n

754

284

102

12

23

1,175

27.6578

29.8415

31.5294

31.5833

30.6522

28.6204

4

n

105

35

14

4

3

161

29.9333

30.4857

34.6429

32.0000

34.6667

30.6025

5

n

458

84

21

1

20

584

26.7445

28.4762

29.1905

13.0000

29.4000

27.1490

Total

n

25,572

6,802

661

109

273

33,417

28.1447

30.2207

30.2648

29.5780

30.1172

28.6299

Suggested Citation:"The Effect of Exposure to the Atomic Bombs on Pregnancy Termination in Hiroshima and Nagasaki." National Research Council. 1991. The Children of Atomic Bomb Survivors: A Genetic Study. Washington, DC: The National Academies Press. doi: 10.17226/1800.
×

through 5.8. It will be noted that the comparison is restricted to unrelated parents. In the following chapter we shall advance reasons for excluding children born to related parents from the analysis. Because of the potential great importance of age-parity differences in this analysis, it has seemed wise to anticipate this decision with respect to this tabulation.

TABLE 5.4 ANALYSISOF VARIANCE: MOTHER'S AGEBY CITYAND PARENTAL EXPOSURE (Unrelated parents) (In this and subsequent tables, one asterisk will be used to denote a value significant at the 5 per cent level, and two asterisks, a value significant at the 1 per cent level.)

Source

Sums of squares of deviations

DF

Mean square

F

Main effects

 

City (C)

21,983.321551

1

21,983.3216

830.86**

Father (F)

43,401.030323

4

10,850.2576

410.08**

Mother (M)

947.687594

4

236.9219

8.95**

Interactions

 

First order

 

CF

74.432938

4

18.6082

1.42

CM

3,107.667017

4

776.9168

29.36**

MF

18,682.813301

16

1,167.6758

44.13**

Higher orders

871.870114

16

54.4919

2.06**

Between classes

94,513.849388

49

1,928.8541

72.90**

Within classes

1,751,484.087605

66,197

26.4587

Total

1,845,997.936993

66,246

   

TABLE 5.5 THE DISTRIBUTIONOF MEAN SQUARESFOR MATERNAL AGEBY CITY, SEXOF INFANT, AND PARENTAL EXPOSURE (Unrelated parents) (The sample numbers are the same as in Table 5.3. The form of the analysis will be discussed in Chapter VI.)

Hiroshima

Nagasaki

 

Fathers

 

Fathers

 
 
 

Sex

1

2

3

4–5

 

Sex

1

2

3

4–5

1

22.160

27.336

29.653

25.529

1

25.376

36.213

40.472

38.920

21.628

24.205

29.271

23.310

25.822

33.257

32.491

32.455

2

21.999

28.964

33.690

28.247

2

28.335

37.926

43.489

31.397

22.327

29.351

40.519

34.122

26.361

38.289