TABLE 4B-1 Doubling Dose Estimates Used in Risk Estimation from the 1950s to the Early 1990s

Reference

DD

Radiation Conditions

Comments

1956 BEAR report (NRC 1956)

50–80 R

40 R

High dose rate (acute)

Guided more by general radiation genetic principles (established mostly from Drosophila studies) than by knowledge of mouse or human mutation rates and, therefore, nothing more than educated guesses; among the principles were (1) linear dose-effect relationship for induced mutations and (2) effect independent of dose rate or dose fractionation.

The general philosophy and “best” estimates of the Medical Research Council (MRC 1958) and UNSCEAR (1958) were roughly similar

UNSCEAR (1962)

100 R

Chronic

Based on mouse data on the reduced effectiveness of chronic γ-irradiation for the induction of specific locus mutations (Russell and others 1958); assumed that DD for males will be about 3 times that of 30 R assumed in UNSCEAR (1958) for acute X-irradiation conditions; noted that DD for females may be higher

Lüning and Searle (1971)

16–51 rads

~100 rads

Acute

Chronic

Based on mouse data for 5 different end points for males; no DD estimate provided for females

1972 BEIR report (NRC 1972)

20–200 rem

Chronic

Based on a range of spontaneous rates in humans (0.5 × 10−6 to 0.5 × 10−5) and a sex-averaged rate of induction of specific locus mutations of 0.25 × 10−7 per locus per rem in mice

Neel and others (1974)

46 rem (Petersen and others 1990)

125 rem (females)

Acute

Based on data on mortality of children born to A-bomb survivors through the first 17 years of life; assumed that for chronic irradiation, the DD for males might be 3 to 4 times 46 rem and as much as 1000 rem for females

Sankaranarayanan (1976); Searle (1976)

80–240 rads

Chronic

Based on mouse data for specific locus mutations induced in spermatogonia and in mature + maturing oocytes and dominant visibles and translocations induced in spermatogonia

UNSCEAR (1977)

100 rads

Chronic

Rationale stated as follows: “Examination of available evidence in the mouse suggests that the use of a 100-rad DD will not underestimate the risk. The ICRP Task Group has also this figure in its calculations …”

1980 BEIR report (NRC 1980)

50–250 rem

Chronic

Based on the “best substantiated” estimate of DD of 114 rem for spermatogonial irradiation of male mice and approximately halving and doubling the above estimate to arrive at the range of 50–250 rem

UNSCEAR (1982)

100 rads

Chronic

No change from the 1977 report

Neel and others (1982); Schull and others (1982)

60 ± 93 rem

135 ± 388 rem

535 ± 2416 rem

135 ± 156 rem

Acute

The first three estimates are based, respectively, on data on UPOs, survival through childhood, and sex chromosomal aneuploids in the Japanese studies; the authors considered that the weighted average of 135 ± 156 rem (last entry) should be multiplied by a factor of 3 to make it applicable to chronic radiation conditions

UNSCEAR (1986)

1 Gy

Chronic

No change from the 1977 report

UNSCEAR (1988)

1 Gy

Chronic

No change from the 1977 report

1990 BEIR report (NRC 1990)

100 rads

Chronic

Overall estimate based on mouse data (both sexes) on several different end points; most estimates given as ranges that vary by factors between about 2 and 30 (a reflection of differences in estimated spontaneous and induction rates); multiplication factors between 5 and 10 used when necessary to convert DD estimates for high-dose-rate irradiation to those for chronic irradiation

Neel and others (1990)

1.69–2.23 Sv

Acute

Composite estimates of “minimal DDs” (DDs at 95% lower confidence limits) compatible with Japanese results on UPOs, F1 mortality, F1 cancer, sex chromosomal aneuploids, and mutations altering protein charge or function; on the assumption of a dose-rate reduction factor of 2, the authors suggest that for chronic low-LET, low-level radiation, the figures are likely to be twice those estimated (i.e., about 3.4 to 4.5 Sv)

Neel and Lewis (1990)

1.35 Gy

Acute

Based on an analysis of mouse data on 7 mutational end points (spermatogonial irradiation experiments); the authors suggest that with the use of a dose-rate factor of 3, the DD will be about 3 Gy

UNSCEAR (Rabes and others 2000)

1 Gy

Chronic

No change from the 1977 report

 

SOURCE: Sankaranarayanan and Chakraborty (2000a).



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