EXPERIENCE OF LONG-TERM OBSERVATION OF AN EXPOSED POPULATION: LESSONS FOR REGIONAL HEALTH MONITORING PROGRAMS

Abstract

Background. Over two decades of medical observation have been conducted among residents living near the Semipalatinsk Nuclear Test Site, an area affected by chronic exposure to ionizing radiation. This study focuses on thyroid diseases, which are known to be among the most radiosensitive conditions following nuclear fallout. Materials and Methods. A cohort of 3,240 individuals who underwent thyroid ultrasound examinations between 1998 and 2002 was selected for long-term follow-up. Vital status, clinical diagnoses, and registry data were regularly updated. In 2023–2024, a detailed questionnaire was administered to 1,099 surviving participants to evaluate lifestyle, behavioral, and reproductive risk factors. Individual thyroid radiation doses were retrospectively estimated based on age at exposure, place of residence, and dietary patterns. Results. The overall prevalence of thyroid disorders reached 63%, with 33% of respondents reporting the use of hormone replacement therapy. The highest rates were observed among individuals with reconstructed thyroid doses in the range of 100–300 mGy. The integration of survey findings with clinical and dosimetric data allowed for a more comprehensive understanding of dose-dependent health effects. Conclusion. The results confirm the long-term impact of low-to-moderate radiation exposure on thyroid health and support the importance of integrated health monitoring approaches. This experience offers practical lessons for developing regional health surveillance systems in other chronically exposed populations.