Environ Health Perspect; DOI:10.1289/ehp.1307737
Iodine-131 and Thyroid Function
Global Health and Environmental Sciences, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
Ostroumova et al. (2013) reported an association between iodine-131 (131I) dose and hypothyroidism in the Belarusian cohort, a cohort of individuals exposed to 131I from fallout of the Chernobyl accident when they were ≤ 18 years of age. Ostroumova et al. also examined other thyroid outcomes: hyperthyroidism, autoimmune thyroiditis, serum concentrations of thyroid-stimulating hormone, and autoantibodies to thyroperoxidase.
It may not be appropriate to include participants with other thyroid outcomes in the analysis because those thyroid outcomes could be indirectly associated with exposure. Chernobyl is in an iodine-deficient area (Ishigaki et al. 2001), and the prevalence of goiters among children ≤ 18 years of age has been reported at > 15% in this area (Hatch et al. 2011). Is high prevalence of goiters in the area caused by normal iodine deficiency or by the 131I? If the goiters were caused by 131I, the relationship between the 131I and hypothyroidism is still unclear, even though Ostroumova et al. (2013) stratified the data according to the presence of goiters. Hypothyroidism can also cause goiters (Wilkins et al. 1954); thus, goiter is just a serious hypothyroidism. That could be the explanation for the higher excess odds ratio in the group with goiter compared with the group without goiter shown in Table 3 of Ostroumova et al. (2013). It would have been better for Ostroumova et al. to perform a stratified analysis on the relationship between 131I and hypothyroidism based on the normal iodine level of the individual rather than the presence of goiter.
Ostroumova et al. (2013) also claimed that the thyroid radioactivity of individuals from the Belarus cohort was based on a previous study (Stezhko et al. 2004). However, Stezhko et al. (2004) did not provide the details of the individual radioactive iodine measurement. Were the original radioactive iodine measurements generated from a formula or modeled based on food intake or soil contamination, or was the 131I exposure level actually measured for each individual? The answer to this question is necessary because the two methods have different credibility. In addition, the exposure described by Stezhko et al. (2004) included 131I as well as other radioactive isotopes of iodine, not 131I alone. I would like to know whether Ostroumova et al. (2013) separated 131I from other radioactive iodine isotopes. Cesium-137 should also be considered as a potential confounder in the relationship between 131I and hypothyroidism.
Hatch M, Polyanskaya O, McConnell R, Gong Z, Drozdovitch V, Rozhko A, et al. 2011. Urinary iodine and goiter prevalence in Belarus: experience of the Belarus–American cohort study of thyroid cancer and other thyroid diseases following the Chornobyl nuclear accident. Thyroid 21:429–437.
Ostroumova E, Rozhko A, Hatch M, Furukawa K, Polyanskaya O, McConnell RJ, et al. 2013. Measures of thyroid function among Belarusian children and adolescents exposed to iodine-131 from the accident at the Chernobyl nuclear plant. Environ Health Perspect 121:865–871; doi: 10.1289/ehp.1205783.
Stezhko VA, Buglova EE, Danilova LI, Drozd VM, Krysenko NA, Lesnikova NR, et al. 2004. A cohort study of thyroid cancer and other thyroid diseases after the Chornobyl accident: objectives, design and methods. Radiat Res 161:481–492.
Wilkins L, Clayton GW, Berthrong M. 1954. Development of goiters in cretins without iodine deficiency: hypothyroidism due to apparent inability of the thyroid gland to synthesize hormone. Pediatrics 13:235–246.
CEHN April 2014 Article of the Month
“Behavioral Sexual Dimorphism in School-Age Children and Early Developmental Exposure to Dioxins and PCBs: A Follow-Up Study of the Duisburg Cohort” [Winneke G, et al. Environ Health Perspect; DOI:10.1289/ehp.1306533] has been selected by the Children’s Environmental Health Network (CEHN) for its April 2014 Article of the Month summary. These summaries discuss the potential policy implications of current children’s environmental health research.
Sign Up to Receive E-mail Alerts
Recent Advance Publications
- Systematic Review and Evidence Integration for Literature-Based Environmental Health Science Assessments
- Association between Source-Specific Particulate Matter Air Pollution and hs-CRP: Local Traffic and Industrial Emissions
- Acrolein-Exposed Normal Human Lung Fibroblasts in Vitro: Cellular Senescence, Enhanced Telomere Erosion, and Degradation of Werner’s Syndrome Protein
- Repeated Nitrogen Dioxide Exposures and Eosinophilic Airway Inflammation in Asthmatics: A Randomized Crossover Study
- Environmental Public Health Dimensions of Shale and Tight Gas Development
- A Framework for the Next Generation of Risk Science
- Maternal Exposure to Criteria Air Pollutants and Congenital Heart Defects in Offspring: Results from the National Birth Defects Prevention Study
- EHPNoonNews: ASM—Cow manure harbors diverse new antibiotic resistance genes http://t.co/WBQJfnNDhO
- EHPNoonNews: Science—Did lead poisoning bring down ancient Rome? http://t.co/Xeu6biD2Sz
- EHPNoonNews: http://t.co/eaZkJLXyEA—Better climate data could help Tanzania curb malaria http://t.co/jMcoSfbLoh
- EHPNoonNews: LouisvilleCourierJournal—New coal dust exposure limits for workers http://t.co/tZcPplZ0jD
- Join CDC for a Twitter chat on the public health approach to autism TODAY at 1pm EST. Participate using hashtag #AutismPHGR