Threshold for radiation-related severe mental retardation in prenatally exposed A-bomb survivors: A re-analysis
Threshold for radiation-related severe mental retardation in prenatally exposed A-bomb survivors: A re-analysis
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DOI：
10.1080/095530096144644
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发表时间：
1996-12-01
影响因子：
2.6
通讯作者：
Lee, S
中科院分区：
文献类型：
--
作者：
Otake, M;Schull, WJ;Lee, S
在排卵后第8 - 25周受辐射的人中，观察到电离辐射对发育中的人脑的显著影响。这些影响，特别是在排卵后8-15周的高度脆弱时期，最显著地表现为严重智力迟钝的频率增加。然而，严重精神发育迟滞病例的分布表明在低剂量区域存在一个阈值。对于基于简单线性模型的个体数据，排卵后8-15周暴露的幸存者的阈值的95%下限为0，而对于排卵后8-15周暴露的幸存者的阈值的95%下限为0。15戈伊，基于我们先前报告（1987）中使用的指数线性模型，但基于所有数据（包括21例已知剂量的额外病例）的阈值的95%下限似乎为0。05戈伊的最大似然估计从指数线性模型。之所以选择后一种模型，是因为从适用于数据的五种模型中估计数的稳定性和合理性来看，它提供了最佳拟合。当从排卵后8-15周暴露的19例智力迟钝病例中排除两例可能与辐射无关的唐氏综合征病例时，阈值的95%下限在0。15-0 . 25戈伊，但在0 . 06-0 .当采用更合理和更好的模型时，剂量为31戈伊。对于基于同一模型的16-25周暴露，阈值的95%下限从0变化。25比0 28戈伊，包括和不包括两个可能的非辐射相关的智力迟钝病例;其中一个病例可能是家族性的，因为有一个智力迟钝的兄弟姐妹，另一个是由于感染，因为该个体在4岁时患有日本B脑炎。
Significant effects on the developing human brain of exposure to ionizing radiation are seen among individuals exposed in the 8th-25th week after ovulation. These effects, particularly in the highly vulnerable period of 8-15 weeks after ovulation, manifest themselves most dramatically as an increased frequency of severe mental retardation. However, the distribution df cases of severe mental retardation suggests a threshold in the low-dose region. The 95% lower bound of the threshold in those survivors exposed 8-15 weeks after ovulation was zero for the individual data based on the simple linear model, and 0 . 15 Gy based on the exponential linear model used in our previous report (1987), but the 95% lower bound of the threshold based on all of the data including 21 additional cases with known doses appears to be 0 . 05 Gy using the maximum likelihood estimates derived from an exponential-linear model. The latter model was selected because it provides the best fit from the standpoint of the stableness and reasonableness of the estimates among the five models applied to the data. When two probably non-radiation-related cases of Down's syndrome are excluded from the 19 mentally retarded cases exposed 8-15 weeks post ovulation, the 95% lower bound of the threshold is in the range of 0 . 15-0 . 25 Gy based on the exponential-linear model used in 1987, but is in the range of 0 . 06-0 . 31 Gy when the more reasonable and better model applied here is used. For exposure in the 16-25-week period based on the same model, the 95% lower bound of the threshold changed from 0 . 25 to 0 . 28 Gy, both with and without inclusion of the two probable non-radiation-related mentally retarded cases; one of these cases was probably familial in origin since there was a retarded sibling, and the other due to infection, since the individual had Japanese B encephalitis at age 4 years.