Thyroid disorders in population living around the Semipalatinsk Nuclear Test Site, Kazakhstan: We still count the victims

INTRODUCTION:   It is well known that the thyroid gland is one of the most radiosensitive human organs. The Semipalatinsk region in Kazakhstan was the sites of Soviet nuclear weapon testing for 40 years. It has been confirmed that thyroid exposure to ionizing radiation increases the risks of thyroid cancer, but we still have lack of knowledge how its influences to benign thyroid disorders. The aim was to evaluate the occurrence of thyroid disorders among affected population living around the Semipalatinsk Nuclear Test Site.

METHODS: Thyroid examinations (palpation, ultrasound and selected laboratory parameters) were conducted in three regions in the East Kazakhstan region (former Semipalatinsk regions) during May-September 2012. The study population in a total amount 4083 (1836 men and 2247 women) were invited for thyroid screening. An estimated dose was 200 to 499 cSv that reflected accumulated lifetime doses in regions of high and increased radiation risk.

RESULTS:   The mean age for participants was 59.43 years. Palpation indicated that more than 35% (95% CI: 32.11 to 37.25) of examined residents had structural thyroid abnormalities. Ultrasound examinations detected thyroid nodules in 28.3% (95% CI: 27.24 to 29.51) and adenomas in 7.9% (95% CI: 5.71 to 6.32) individuals. Abnormalities of thyroid stimulating hormone (TSH) was found 19.14% – hypothyroidism (95% CI: 18.60 to 22.36) and 2.13% – hyperthyroidism (95% CI: 1.04 to 3.51). Markers of autoimmune thyroid disease (high level of anti-peroxidase antibody – TPOAb) were revealed in 42% (95% CI: 37.15 to 43.11) screened population.

CONCLUSIONS:   The study indicated the high prevalence of structural (nodules and adenomas – 36.2%), functional (hypothyroidism – 19.14%) including autoimmune thyroid disease among the affected population (42%). This fact underlined possibility radiation induced immunodeficiency and development of another autoimmune diseases in each second affected individual or offspring. We still count the victims of the nuclear weapon testing in former Semipalatinsk regions. Future studies and development of rehabilitation programs should be one of priorities for the scientific community and the government.