Thyroid dose estimations in fetus and new-borns after the Chernobyl accident

A method of a dose estimation in fetal thyroid due to 131I intake into mothers body living on a territory contaminated with radionuclides after the Chernobyl accident is described. The initial value for calculations was the thyroid dose in mother formed due to a prolonged 131I intake with contaminated food and air. The absorbed fetal thyroid dose is dependent on pregnancy time on the day of radioactive fallout. It did not differ from the average tissue dose during pregnancy less than 75 days and was the highest, approximately twice as high as the mothers thyroid dose in case when the age of fetus was from 100 to 140 days at the time of accident. The fetal thyroid dose became smaller with increasing of fetal age. The thyroid dose in a new-born child could be formed due to a pre-natal 131I uptake in fetal thyroid and due to 131I intake with maternal milk after its birth if the accident happened at the last month of a pregnancy. The thyroid dose in a breast-feed new-born was higher by a factor of 3.5±0.2 than a thyroid dose in its mother following the Chernobyl accident.