Radiation-induced congenital malformations in Fukushima after the Fukushima Daiichi Nuclear Disaster

The Fukushima Daiichi Nuclear Disaster (FDND) occurred in 2011, which occurred after the Great East Japan Earthquake. However, how the incidence of radiation-induced malformations in Fukushima has been affected by FDND remains to be elucidated. To address this, we analyzed birth data from Fukushima and other areas in Japan from the International Clearinghouse for Birth Defects Surveillance and Research Japan Center, including information on birth defects between January 2010 and December 2022. Among the registered birth defects, microcephaly, microphthalmia, and neural tube defects were classified as radiation-induced malformations. Our study included 90 433 births in Fukushima, accounting for 52.6% of all births. Among these, birth defects were observed in 1376 (1.52%) births, of which 28 (0.031%) were diagnosed with radiation-induced malformations. With regard to other areas in Japan, 1 323 391 births, which accounted for 10.9% of all births, were registered; births with birth defects and radiation-induced malformations were observed in 37 490 (3.67%) and 889 (0.067%), respectively. Because sampling bias was suspected, we compared the rates of radiation-induced malformations in Fukushima and other areas in Japan by adjusting the incidence in Fukushima with the incidences of ventricular septal defects in both areas. However, there was no statistically significant difference between them. Our results, which covered the largest number of births in Fukushima, did not find a significant increase in the incidence of radiation-induced malformations in Fukushima since FDND.