Evaluation of thyroid antibodies and benign disease prevalence among young adults exposed to (131)I more than 25 years after the accident at the Chernobyl Nuclear Power Plant.

Background. The Chernobyl Nuclear Power Plant (CNPP) accident exposed a large number of inhabitants to internal (131)I radiation. The associations between internal (131)I exposure and thyroid autoimmunity and benign thyroid diseases remain controversial in the population living in the contaminated area around the CNNP. In this study, we evaluate the association of (131)I with benign thyroid diseases. Methods. We compared the prevalence of Anti-Thyroid Autoantibodies (ATAs), thyroid function, and prevalence of thyroid ultrasound finding outcomes in 300 residents of the contaminated area of Ukraine who were 0-5 years of age at the time of the CNPP accident (group 1) and 300 sex-matched residents who were born after the accident (group 2). Results. We did not find any differences of the prevalence of Antithyroglobulin Antibodies (TGAb) positive, Antithyroid Peroxidase Antibodies (TPOAb) positive, and TGAb and/or TPOAb positive between the study groups. (11.7% vs 10.3%; p = 0.602, 17.3% vs 13.0%; p = 0.136, 21.0% vs 17.3%; p = 0.254, respectively); after adjusting for age and sex, the prevalence was not associated with the (131)I exposure status in the study groups. The prevalence of subclinical and overt hypothyroidism cases was not significantly different (p = 0.093 and p = 0.320) in the two groups, nor was the prevalence of goiter (p = 0.482). On the other hand, the prevalence of nodules was significantly higher in group 1 (p = 0.003), though not significantly so after adjustment for age and sex. Discussion. Working 26-27 years after the CNNP accident, we found no increased prevalence of ATAs or benign thyroid diseases in young adults exposed to (131)I fallout during early childhood in the contaminated area of Ukraine. Long-term follow-up is needed to clarify the effects of radiation exposure on autoimmunity reaction in the thyroid.

Evaluation of the Relationship between Current Internal 137Cs Exposure in Residents and Soil Contamination West of Chernobyl in Northern Ukraine.

After the Chernobyl Nuclear Power Plant accident, the residents living around the Chernobyl were revealed to have been internally exposed to 137Cs through the intake of contaminated local foods. To evaluate the current situation of internal 137Cs exposure and the relationship between the 137Cs soil contamination and internal exposure in residents, we investigated the 137Cs body burden in residents who were living in 10 selected cities from the northern part of the Zhitomir region, Ukraine, and collected soil samples from three family farms and wild forests of each city to measured 137Cs concentrations. The total number of study participants was 36,862, of which 68.9% of them were female. After 2010, the annual effective doses were less than 0.1 mSv in over 90% of the residents. The 137Cs body burden was significantly higher in autumn than other seasons (p < 0.001) and in residents living in more contaminated areas (p < 0.001). We also found a significant correlation between the proportion of residents in each city with an estimated annual exposure dose exceeding 0.1 mSv and 137Cs concentration of soil samples from family farms (r = 0.828, p = 0.003). In conclusion, more than 25 years after the Chernobyl accident, the internal exposure doses to residents living in contaminated areas of northern Ukraine is limited but still related to 137Cs soil contamination. Furthermore, the consumption of local foods is considered to be the cause of internal exposure.

Urinary iodine concentrations of pregnant women in Ukraine.

BACKGROUND: Iodine requirements increase during pregnancy and previous studies have reported the inadequate iodine status of pregnant women in areas that have achieved iodine sufficiency in the general population. We examined the urinary iodine (UI) concentrations of pregnant women in Ukraine, where the iodine status is showing improvement among the general population. METHODS: We enrolled 148 pregnant women<16 weeks pregnant and 80 healthy women as a control group living in Zhitomir, Ukraine. UI concentration, thyroid-stimulating hormone (TSH), antithyroglobulin antibodies (TGAb), and antithyroid peroxidase antibodies (TPOAb) were measured. RESULTS: The median UI concentrations were significantly lower in pregnant women than in control women [13.0 (ND­51.0) µg/L vs. 62.0 (35.3­108.5) µg/L, p<0.001]. TSH concentrations were significantly lower in pregnant women than in control women [1.7 (1.2­2.7) IU/L vs. 2.2 (1.4­3.1) IU/L, p=0.011], but this difference disappeared when adjusted for age (2.1±0.1 IU/L vs. 2.4±0.2 IU/L, p=0.097). The frequency of TSH over 6.2 IU/L and the frequency of positive TGAb and/or TPOAb were not statistically different between groups (p=0.70 and p=0.48, respectively). The UI concentrations of 142 pregnant women (95.9%) were <150 µg/L indicating insufficient iodine intake. CONCLUSIONS: The UI concentration of pregnant women in Ukraine revealed severe iodine deficiency. Regular monitoring and appropriate nutrition education are essential because iodine deficiency can be easily prevented by adequate iodine intake. The risk of iodine deprivation during pregnancy needs to be assessed locally over time because it may occur in areas that are not globally recognized as being iodine-deficient.