Prevalence of thyroid abnormalities among children of the south-west area of the Kaluga oblast exposed to radiation in utero during different periods of gestation

Cohort study examined incidence of thyroid abnormalities in 560 children under 12 years of age resided in south-west area of the Kaluga oblast with iodine deficiency and contamination with radionuclides following the Chernobyl accident. The children were exposed to radiation from iodine-131 in utero during different periods of gestation, 140 children were exposed to radiation partly in utero and partly in the first weeks (up to 13 weeks) of life. Thyroid abnormalities prevalence among exposed in utero and unexposed 190 children of the same age and territory of residence was compared. Morbidity among exposed children was 2.3 times higher than that among unexposed children. The thyroid was shown to be more sensitive to radiation from incorporate iodine-131 in the 9-14th weeks of gestation and in the first weeks of postnatal period.