Risk of Thyroid Nodules in Residents of Belarus Exposed to Chernobyl Fallout as Children and Adolescents.

Context: Although radiation exposure is an important predictor of thyroid cancer on diagnosis of a thyroid nodule, the relationship between childhood radiation exposure and thyroid nodules has not been comprehensively evaluated. Objective: To examine the association between internal I-131 thyroid dose and thyroid nodules in young adults exposed during childhood. Design, setting, and participants: In this cross-sectional study, we screened residents of Belarus aged ≤18 years at the time of the Chernobyl nuclear accident for thyroid disease (median age, 21 years) with thyroid palpation, ultrasonography, blood/urine analysis, and medical follow-up when appropriate. Eligible participants (N = 11,421) had intact thyroid glands and doses based on direct individual thyroid activity measurements. Main outcome measures: Excess odds ratios per Gray (EOR/Gy, scaled at age 5 years at exposure) for any thyroid nodule and for nodules grouped by cytology/histology, diameter size, and singularity. Results: Risk of any thyroid nodule increased significantly with I-131 dose and, for a given dose, with younger age at exposure. The EOR/Gy (95% confidence intervals) for neoplastic nodules (3.82; 0.87 to 15.52) was significantly higher than for nonneoplastic nodules (0.32; <0.03 to 0.70) and did not vary by size; whereas the EOR/Gy for nonneoplastic nodules did vary by size (P = 0.02) and was 1.55 (0.36 to 5.46) for nodules ≥10 mm and 0.02 (<-0.02 to 0.70) for nodules <10 mm. EORs/Gy for single and multiple nodules were comparable. Conclusions: Childhood exposure to internal I-131 is associated with increased risk of neoplastic thyroid nodules of any size and nonneoplastic nodules ≥10 mm.

Risk of thyroid follicular adenoma among children and adolescents in Belarus exposed to iodine-131 after the Chornobyl accident.

Several studies reported an increased risk of thyroid cancer in children and adolescents exposed to radioactive iodines, chiefly iodine-131 ((131)I), after the 1986 Chornobyl (Ukrainian spelling) nuclear power plant accident. The risk of benign thyroid tumors following such radiation exposure is much less well known. We have previously reported a novel finding of significantly increased risk of thyroid follicular adenoma in a screening study of children and adolescents exposed to the Chornobyl fallout in Ukraine. To verify this finding, we analyzed baseline screening data from a cohort of 11,613 individuals aged ≤18 years at the time of the accident in Belarus (mean age at screening = 21 years). All participants had individual (131)I doses estimated from thyroid radioactivity measurements and were screened according to a standardized protocol. We found a significant linear dose response for 38 pathologically confirmed follicular adenoma cases. The excess odds ratio per gray of 2.22 (95% confidence interval: 0.41, 13.1) was similar in males and females but decreased significantly with increasing age at exposure (P < 0.01), with the highest radiation risks estimated for those exposed at <2 years of age. Follicular adenoma radiation risks were not significantly modified by most indicators of past and current iodine deficiency. The present study confirms the (131)I-associated increases in risk of follicular adenoma in the Ukrainian population and adds new evidence on the risk increasing with decreasing age at exposure.

Proportionate cancer mortality among workers in the Belarussian tanning industry.

BACKGROUND: The tanning industry involves many occupational exposures. This study evaluates proportionate cancer mortality among workers employed in the Belarussian tanning plant in Minsk. METHODS: A total of 768 workers with seniority of not less than 6 months who were hired after January 1, 1953 and died before December 31, 2000 was investigated. Proportionate mortality ratios (PMRs) were calculated using the population of Minsk to generate expected numbers. RESULTS: Among women employed in the tannery, there was a significant excess of pancreatic cancer, based on eight deaths (expected = 2.56, PMR = 3.13, 95% CI = 1.35-6.17). Six of the eight pancreatic cancer deaths occurred among women occupied in dyeing-stuffing workshops (expected = 1.64, PMR = 3.67, 95% CI = 1.34-7.97), all among workers hired between 1962 and 1984 (expected = 1.06, PMR = 6.54, 95% CI = 2.6-13.4). CONCLUSIONS: Women in this tanning industry cohort experienced excess mortality of cancer of the pancreas, with suggested increases of corpus and cervix uteri, melanoma, and kidney cancers. For men, an insignificant increase in PMR of oral cavity-pharynx and pancreatic cancers was seen. Further prospective follow-up of living members of this cohort, will allow more in-depth analysis of rare cancer sites, latency, and duration of employment, and is warranted.