This paper describes methods for estimating thyroid doses to Ukrainian children who were subjects of an epidemiological study of prenatal exposure and presents the calculated doses. Participants were 2,582 mother-child pairs in which the mother had been pregnant at the time of the Chernobyl accident on 26 April 1986 or in the 2–3 mo following when 131I in fallout was still present. Among these, 1,494 were categorized as “exposed;” a comparison group of 1,088 was considered “relatively unexposed.” Individual in utero thyroid dose estimates were found to range from less than 1 mGy to 3,200 mGy, with an arithmetic mean of 72 mGy. Thyroid doses varied primarily according to stage of pregnancy at the time of exposure and level of radioactive contamination at the location of residence. There was a marked difference between the dose distributions of the exposed and comparison groups, although nine children in the latter group had calculated doses in the range 100–200 mGy. For those children who were born after the accident and prior to the end of June 1986, postnatal thyroid doses were also estimated. About 7.7% (200) of the subjects received thyroid doses after birth that were at least 10% of their cumulative doses.
* Scientific Research Center for Radiation Medicine, Division of Dosimetry and Radiation Hygiene, 53 Melnikova Street, Kyiv, Ukraine; † Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 6120 Executive Boulevard, Bethesda, MD 20892; ‡ International Atomic Energy Agency, Wagramer Strasse 5, P.O. Box 100, A-1400 Vienna, Austria; § MJP Risk Assessment, Inc., P.O. Box 200937, Denver, CO 80220-0937.
For correspondence contact: André Bouville, DHHS/NIH/NCI/Division of Cancer Epidemiology and Genetics, Executive Plaza South, EPS-7094, Bethesda, MD 20892, or email at firstname.lastname@example.org.
(Manuscript accepted 29 September 2010)