Health Effects of Exposure to Low Levels of Ionizing Radiation BEIR V (1990) / Chapter Skim
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7 Low Dose Epidemiologic Studies
7 Low Dose Epidemiologic Studies
Pages 371-390
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From page 371... ...
, this Committee considered populations exposed to radiation from a number of different sources: diagnostic radiography, fallout from nuclear weapons testing, nuclear installations, radiation in the work place, and high levels of natural background radiation. Studies of prenatal exposures to diagnostic x rays are discussed in Chapter 6.
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From page 372... ...
The odds ratio for exposure to 0-0.99, 1.00-9.99, 10.00-19.99, and > 20.0 Gray in the 3-20 years prior to diagnosis were 1.0, 1.4, 1.7, and 2.4, respectively (o for the highest exposure category, p < 0.05~. The association was strongest for the period 6-10 years prior to diagnosis, and the effect of radiation exposure during this period remained significant after consideration of other risk factors in a logistic regression analysis.
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From page 373... ...
FALLOUT FROM NUCLEAR WEAPONS TESTING In the late 1970s, several studies reported excess cancer, primarily leukemia, among persons who were exposed to fallout from nuclear weapons tests. These included residents of Utah and neighboring states downwind of the Nevada Test Site (NTS)
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Moreover, compared to the "unexposed cohort," rates for eastern Oregon, Iowa, and the total United States were also higher by about the same amount.
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From page 375... ...
(Ra87) carried out a cohort study of 954 Canadian military personnel who had been involved in clean-up operations after nuclear reactor accidents at ChaLk River Nuclear Laboratories or who had observed nuclear weapons blasts in the United States or Australia; two matched controls were selected from military records for each exposed subject.
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compared time trends in global fallout across the United States with trends in leukemia rates. Fallout activity was estimated from measurements of beta emissions, airborne particulates, precipitation, and i3iI in milk.
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CANCER AMONG INDIVIDUALS NEAR NUCLEAR INSTALLATIONS Nuclear Reactor Accidents It is still too early to assess whether any cancer excess will occur following the Three Mile Island or Chernobyl nuclear reactor accidents. The collective dose equivalent resulting from the radioactivity released in the Three Mile Island accident was so low that the estimated number of excess cancer cases to be expected, if any were to occur, would be negligible and undetectable (Fable.
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From page 378... ...
examined cancer mortality in individuals living near 14 nuclear and 5 nonnuclear facilities in England and Wales and found no overall pattern of increasing cancer SMRs in individuals living around the nuclear facilities. A more comprehensive survey of cancer incidence and mortality near nuclear installations for the period 1959-1980 is reported by the United Kingdom Office of Population Censuses and Surveys (Co87a, Foam.
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From page 379... ...
Whether the excesses will be found to be balanced by a comparable number of deficiences around other nuclear installations, or whether they will prove to occur more consistently than not, are questions calling for further study. EPIDEMIOLOGIC STUDIES OF WORKERS EXPOSED TO LOW DOSE, LOW-LET RADL\TION A number of epidemiologic studies of individuals exposed occupationally to low levels of low-LET radiation have been reported.
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From page 380... ...
A significant excess of prostate cancer has been observed in the United Kingdom Atomic Energy Authority study (Be85) , but this excess seems to be associated, in part, with exposures to multiple forms of radiation, including tritium and other internal nuclides.
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From page 381... ...
_ _ Cat ~ ', X X r - .
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=> == E E O ~ v' is c:.= 3 a To v, en ~d ~ 0 0 ~ ILL cL ~ O 0 ~ oo ~on ED or a x cat ..
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From page 383... ...
Because the total dose rate of low-LET natural background radiation is low, and the lifetime dose of such radiation accumulated by any one person is small (<0.1 Gy) , it is difficult to determine whether there are any variations in disease rates associated with changes in natural background radiation levels and, if so, whether such variations are consistent with the health effects estimated by extrapolation from the observed effects of high-dose and high dose-rate exposures.
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From page 384... ...
Studies of the health of this population are limited, but a cytogenetic study of 200 individuals, in comparison with a control group from a similar village, reported an increase in the total number of chromosome aberrations (Baby. Kerala, India The population living along the Kerala Coast of India is exposed to about 4 times the normal level of natural background radiation (excluding radon progeny in the lung)
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From page 385... ...
Summary In areas of high natural background radiation, an increased frequency of chromosome aberrations has been noted repeatedly. The increases are consistent with those seen in radiation workers and in persons exposed at high dose levels, although the magnitudes of the increases are somewhat larger than predicted.
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1988. Radiation doses and cause specific mortality among workers at a nuclear materials fabrication plant.
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~ _.. w _ _ of occupational radiation exposure in the United Kingdom Atomic Energy Authority mortality study.
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From page 388... ...
125:44-61. National Research Council, Committee on the Biological Effects of Ionizing Radiations.
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From page 389... ...
27:141-150. United Nations Scientific Committee on the Effects of Atomic Radiations (UNSCEAR)
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