Teratogen update: Radiation and Chernobyl

The 1986 nuclear reactor accident at Chernobyl caused nonuniform radioconta mination of air and land, primarily within regions of the former Soviet Uni on and Western Europe. Major exposure groups included the reactor workers, villagers evacuated from within 30 km of the accident, the "liquidators" wh o decontaminated the evacuation zone afterward, those in radiocontaminated villages not evacuated, and "others" not in the latter categories. The poss ibility of being exposed to radiation caused considerable anxiety, especial ly among pregnant women. Were teratogenic levels of radiation (greater than or equal to 0.1 Gy) exposure attained? To date there is no consistent proo f that this level of radiation exposure was received. Nevertheless, thousan ds of induced abortions were performed. Radioiodine (I-131) caused thyroid cancer in young children in portions of Belarus, the Ukraine, and Russia. I t is not known but very possible that I-131 fetal thyroid exposure contribu ted to this observation. The relationship between mental retardation and ra diation exposure has not been confirmed. Leukemia and other cancers, while predicted for the liquidators (mainly males), has not been found in the oth er exposure groups at this time. Investigations of aborted fetuses and newb orns in Belarus showed an increase in the frequency of both congenital and fetal abnormalities in high and low Cs-137 contaminated regions. This study is unreliable due to detection and selection biases. Accident and environm ental factors unrelated to radiation doses may have contributed to these ob servations. Occasional positive teratogenic studies in less contaminated re gions of Western Europe are suspect because of the low radiation doses rece ived. There is no substantive proof regarding radiation-induced teratogenic effects from the Chernobyl accident. (C) 1999 Wiley-Liss, Inc.