Study on the Effect of Atomic Bomb Radiation on Thyroid Function

The thyroid function of 6112 cases directly exposed to the atomic bomb within 1.5 km (exposed group) and of 3047 cases directly exposed beyond 3.0 km from the hypocenter (control group) was analyzed and the following results were obtained.
1) The frequency distribution curves of TSH values of both groups closely resembled each other in males, but the curve of the exposed group deviated to the right due to high TSH values. In females, the distribution width of TSH values of the exposed group was wide with a low peak and when compared to the control group, the curve was remarkably deviated to the right due to TSH values.
2) The frequency of hypothyroidism was 1.22% in males of the exposed group and 0.35% in males of the control group, while in females it was 7.08% and 1.18%, respectively, showing a significantly higher rate in the exposed group in both sexes. By exposure dose, the frequency was 1.03% in males of the 1-99 rad group and with increase of exposure dose the frequency elevated, being 3.67% at exposure dose of 200 rad or more. In females, the frequency was 6.23% and 7.76%, respectively, showing a significantly higher frequency when compared to the control group.
3) The prevalence rate of positive MCHA among the cases of hypothyroidism was 16.4% in males of the exposed group and 88.9% in males of the control group, while in females the prevalence was 25.3% and 63.3%, respectively, showing a remarkably low rate in the exposed group.