Scientific Protocol for the Study of Thyroid Cancer and Other Thyroid Disease in Ukraine Following the Chernobyl Accident

The nuclear power plant accident at Chornobyl released large quantities of Iodine-131 and other radioisotopes of iodine in the atmosphere, contaminating thousands of square kilometers and exposing millions of people. For this study, a well-defined subset of Ukrainian children aged 0-18 years or in utero at the time of the accident are being identified and examined by well-trained specialists for thyroid disease every two years for at least three cycles. The study is a collaborative effort of research in Ukraine and the United States. The cohort will include approximately 13,000 persons who were children in 1986, all or most of whom have had their thyroids measured for radioactivity during the weeks immediately following the accident (or whose mothers had measurements taken while the child was in utero). Under a rigid research protocol these subjects will receive diagnostic thyroid examinations, including palpation, ultrasound scanning, thyroid hormone and other laboratory tests, and, if indicated, fine-needle aspiration biopsy. Interview information regarding residential, health, diet and lifestyle history will also be collected. All subjects will be followed for thyroid cancer morbidity and mortality. Thyroid cancers will be confirmed by expert pathology examination of tissue. In addition to the analysis of thyroid radiation measurements made in May-June, 1986, efforts will be made to reconstruct each person's exposure and to estimate the radiation dose to the thyroid. This will involve the reconstruction of deposition patterns and environmental pathways of the radioiodines, and of the location, dietary characteristics, and lifestyle of each person throughout the exposure period. The aim of the study is to carry out valid and credible assessments of the early and late morphologic and functional changes in the thyroid glands of persons exposed to radiation from radioactive materials released as a consequence of the Chornobyl nuclear power plant accident. The emphasis is on dose- and time-specific changes. In the course of the study other possible risk factors will be examined including dietary iodine intake during and after 1986, and the ingestion of potassium iodide for thyroid protection shortly after the accident.