The Children of Atomic Bomb Survivors A Genetic Study (1991) / Chapter Skim
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The Children of Parents Exposed to Atomic Bombs: Estimates of the Genetic Doubling Dose of Radiation for Humans
The Children of Parents Exposed to Atomic Bombs: Estimates of the Genetic Doubling Dose of Radiation for Humans
Pages 431-450
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From page 431... ...
YoshimotoT * Department of Human Genetics, University of Michigan Medical School, Ann Arbor; tCenter for Demographic and Population Genetics, University of Texas, Houston; and "Radiation Effects Research Foundation, Hiroshima Summary The data collected in Hiroshima and Nagasaki during the past 40 years on the children of survivors of the atomic bombings and on the children of a suitable control population are analyzed on the basis of the newly revised estimates of radiation doses.
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From page 432... ...
Setting the earliest date for admission into the cohort at May 1, 1946, effectively eliminates from the sample all children in utero ATB. These cohorts have been periodically expanded to include matched numbers of recent births, the limiting factor in the expansion being the number of births to the proximally exposed parents.
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From page 433... ...
Inasmuch as gonadal doses must be available for both parents in a genetic study, and since the "DS86 dose unassigned group" tends to involve predominantly the proximally (more heavily) exposed parents, failure to assign a revised dose to this group would result in a sacrifice of, for example, 23% of the children in the first study we will summarize, i.e., the study on untoward pregnancy outcomes.
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From page 434... ...
The general thesis undergirding the search for an increase in UPOs as an indicator of the genetic effects of the atomic bombs is that some portion of this outcome is due to newly arisen, dominantly expressed mutation in the parental generation. We will discuss the probable magnitude of this fraction later.
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From page 435... ...
. The average conjoint parental gonadal dose for the parents receiving >0.01 Sv is, of course, the same as for the preceding data set.
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From page 436... ...
We have now calculated that, on the basis of an RBE of 20 for neutrons, the mean conjoint parental gonad dose for the parents receiving >0.01 Sv is 0.60. Unlike the results to be presented for the other studies, we have not calculated the regression of indicator on parental exposure because of the paucity of proven mutations.
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From page 437... ...
We have now reestimated, with the standard procedure, these conjoint gonad doses for parents whose dose was >0.01 Sv, by using the total sample and value of 20 as the RBE for neutrons. The estimated conjoint dose for the proximally exposed 13,544 sets of parents is 0.41 Sv.
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From page 438... ...
first demonstrated the genetic effects of radiation, and in the early years of this Genetics Program the sex ratio-i.e., the ratio of male births to female births among the offspring of proximally and distally exposed survivors-received considerable attention (Neel and Schull 1956; Schull et al.
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From page 439... ...
In all three of these approaches, we take it as a given that the exposure resulted in mutations in some survivors of the atomic bombings, inasmuch as, without exception, under controlled laboratory conditions ionizing radiation has produced mutations in every properly studied plant and animal species. Approach The simplest approach is to content ourselves with the statement that the children of what is almost certainly the most highly irradiated population in the world's history provide, with the present indicators, no statistically significant evidence that mutations were produced in their parents.
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From page 440... ...
For instance, were the female to exhibit both spontaneous and induced rates of zero, the ratio of Za/~f would still be the average gametic doubling dose. To restate the now obvious, while the estimate of the impact that spontaneous mutation in the parental generation has on the zygote Estimate of Gametic Doubling Doses That Can Be Excluded at Specified Confidence Levels by These Data OBSERVED TOTAL MUTATIONAL SV AT LOWER CONFIDENCE BACK- CONTRIBUTION MUTATIONAL REGRESSION LIMIT OF GROUND BACKGROUND COMPONENT_ TRAIT (a)
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From page 441... ...
xblir~g-dose estimate most needled is of the amount of parental radiatior' that in the f rst generation will result in the same impact of genetic mortality arid morbidity as would result from spontaneous mutation in these same parents. Ideally, the genetic doubling dose is calculated as that amount of radiation which increases the total impact of spontaneous mutation by 100%.
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From page 442... ...
We believe, however, that throughout we have been conservative in our assumptions. Furthermore, we have reported that the parents who were unexposed to the effects of the atomic bombings (who came to Hiroshima and Nagasaki after the bombings, as released servicemen, repatriates, Summary of Regression of Various Indicators on Parental Radiation Exposure and of Impact of Spontaneous Mutation on Indicator Regression / Combined Contribution of Trait Parental Sv Spontaneous Mutation UPO +.00264~ F
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From page 443... ...
The radiation doses received from the atomic bombings were very high energy and very brief-the estimated individual gonadal doses among those receiving increased radiation were 0.01-3.0 Sv, the average being about 0.25 Sv. The complex issues involved in extrapolating from such a situation to the effect of the low-level, chronic or intermittent exposures which are the usual lot of hu man populations are well discussed in report 64 of the National Council on Radiation Protection (1980~.
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From page 444... ...
(3) The extended period over which these observations have been assembled allows for any attenuation of genetic effects THE CHILDREN OF ATOMIC BOMB SURVIVORS 444
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From page 445... ...
With respect to protein variants, sex-chromosome aneuploids, and balanced structural rearrangements of chromosomes, the individuals resulting from mutation in the parental generation can be directly identified by the appropriate studies on the parents, and we have already indicated in the text the base-line mutation rates observed in the offspring of the distally exposed. For three indicators-untoward pregnancy outcomes, mortality among live-born infants, and Fat cancer-we must proceed more circumspectly.
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From page 446... ...
, and the data on Caucasians (Jacobs 1981~. Our family studies on the children of unexposed parents revealed a spontaneous mutation rate for this endpoint (based on a single event)
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From page 447... ...
National Academy of Sciences (see Committee on the Biological Effects of Ionizing Radiations, National Research Council 1980) and the various United Nations Scientific Committees on the Effects of Atomic Radiation (see the 1986 Report)
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From page 448... ...
Awa AA (1975) Genetic effects: cytogenetic study.
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From page 449... ...
Search for mutations affecting protein structure in children of atomic bomb survivors: preliminary report. Proc Natl Acad Sci USA 77:4221-4225 Neel JV, Schull WJ (1956)
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From page 450... ...
Am ~ Hum Genet 18:328-338 Schull WJ, Otake M, Neel JV (1981) Genetic effects of the atomic bombs: a reappraisal.
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