Epidemiological studies on disturbances of human fetal development in areas with various doses of natural background radiation. II. Relationship between incidences of hydatidiform mole, malignant hydatidiform mole, and chorionepithelioma and gonad dose equivalent rate of natural background radiation.

The relationships between gonad dose equivalent rates and incidences of chorionic disease (i.e., hydatidiform mole, malignant hydatidiform mole, and chorionepithelioma) were analyzed with Kendall's rank correlation and regression methods. Data used were from 11 prefectures of Japan with various dose rates of natural background ionizing radiation between the years 1974 to 1976. The results suggested an association of the incidence of chorionic disease with the radiation dose rate in the very low dose-rate range.