Childhood exposure to internal I-131 is associated with increased risk of neoplastic thyroid nodules of any size and nonneoplastic nodules ≥10 mm.

The cohort of 768 workers who were actively employed for a minimum of 6 months and died was retrospectively followed from 1 January 1953 to 31 December 2000. There were 328 women and 440 men observed. Proportionate mortality ratios (PMRs) were calculated using the Minskcity population mortality proportions to generate expected numbers. The significant excess of pancreatic cancer (PMR=366%; 95%CI=134-800) and melanoma and skin cancer (PMR=455%; 95%CI=123-1,164) in women-workers of Dyeing and stuffing workshops was shown. The significantly high mortality from pancreatic cancer among Dyeing and stuffing workshops' female workers hired and discharged between 1958 and 1984 (PMR=1,024%; 95%CI=11-2,109), melanoma and skin cancer (PMR=440%; 95%CI=240-2,327) among Dyeing and stuffing workshops female workers who started before 1970, lip and buccal cavity among men who began working within 1974-1978 (PMR=1,071%; 95%CI=220-3,128), cervix and corpus uteri cancer among workers employed before1960 was found. It should be noted that the significantly high mortality from above noted cancers was indicated for Dyeing and stuffing workshops female workers with seniority more than 10 yr. Thus it was shown for pancreatic cancer (PMR=418%; 95%CI=136-975), for melanoma and skin cancers (PMR=497%; 95%CI=102-1,450), for uterus cancers (PMR=269%; 95%CI=130-496).

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.

In this study, we expanded on a previously published population-based case-control study on subjects exposed to iodine-131 (131I) from Chernobyl fallout at age ≤18 years using improved individual 131I absorbed thyroid doses. We further studied the impact of iodine deficiency and other selected host risk factors on 131I-related thyroid cancer risk after childhood exposure. We included 298 thyroid cancer cases and 1934 matched controls from the most contaminated regions of Belarus and the Russian Federation. We performed statistical analysis using conditional logistic regression models. We found a statistically significant linear quadratic dose-effect association between thyroid cancer and 131I thyroid dose in the range up to 5 grays (Gy). Self-reported personal history of benign nodules, any thyroid disease except thyroid cancer, family history of thyroid cancer, increased body mass index, and deficient stable iodine status at the time of the accident were statistically significant risk factors (p < 0.05 for each factor) for thyroid cancer after adjustment for thyroid 131I dose effect. Subjects who received stable iodine supplementation in the years after the accident had a significantly lower 131I-related risk of thyroid cancer. Our findings are important for thyroid cancer prevention, and for further improvement of medical surveillance in the affected populations.

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.