Childhood Thyroid Radioiodine Exposure and Subsequent Infertility in the Intermountain Fallout Cohort

Mary Bishop Stone,* Joseph B. Stanford, Joseph L. Lyon, James A. VanDerslice, and Stephen C. Alder


University of Utah Department of Family and Preventive Medicine, Salt Lake City, Utah, USA


Abstract

Background: Above-ground and underground nuclear weapon detonation at the Nevada Test Site (1951–1992) has resulted in radioiodine exposure for nearby populations. Although the long-term effect of environmental radioiodine exposure on thyroid disease has been well studied, little is known regarding the effect of childhood radioiodine exposure on subsequent fertility. 


Objectives: We investigated early childhood thyroid radiation exposure from nuclear testing fallout (supplied predominantly by radioactive isotopes of iodine) and self-reported lifetime incidence of male or female infertility or sterility. 


Methods: Participants were members of the 1965 Intermountain Fallout Cohort, schoolchildren at the time of exposure who were reexamined during two subsequent study phases to collect dietary and reproductive histories. Thyroid radiation exposure was calculated via an updated dosimetry model. We used multivariable logistic regression with robust sandwich estimators to estimate odds ratios for infertility, adjusted for potential confounders and (in separate models) for a medically confirmed history of thyroid disease. 


Results: Of 1,389 participants with dosimetry and known fertility history, 274 were classified as infertile, including 30 classified as sterile. Childhood thyroid radiation dose was possibly associated with infertility [adjusted odds ratio (AOR) = 1.17; 95% CI: 0.82, 1.67 and AOR = 1.35; 95% CI: 0.96, 1.90 for the middle and upper tertiles vs. the first tertile of exposure, respectively]. The odds ratios were attenuated (AOR = 1.08; 95% CI: 0.75, 1.55 and AOR = 1.29; 95% CI: 0.91, 1.83 for the middle and upper tertiles, respectively) after adjusting for thyroid disease. There was no association of childhood radiation dose and sterility. 


Conclusion: Our findings suggest that childhood radioiodine exposure from nuclear testing may be related to subsequent adult infertility. Further research is required to confirm this.


Key words: child, infertility, nuclear weapons, radioisotopes, sterility, thyroid disease. 


Environ Health Perspect 121:79–84 (2013). http://dx.doi.org/10.1289/ehp.1104231 [Online 25 October 2012]


Address correspondence to J.B. Stanford, Department of Family and Preventive Medicine, University of Utah, 375 Chipeta Way, Suite A, Salt Lake City, UT 84108 USA. Telephone: (801) 587-3331. Fax: (801) 587-3353. E-mail: joseph.stanford@utah.edu


*Deceased. 


We thank F.O. Hoffman (SENES Oak Ridge); L. Anspaugh (University of Utah, Radiobiology Division); S. Simon (National Cancer Institute, Division of Cancer Epidemiology and Genetics); R. Carroll (Texas A&M University, Department of Statistics); and J. Panichello, J. Kim, K. Schliep, T. Green, and M. Ward (University of Utah, Department of Family and Preventive Medicine) for their assistance with this manuscript. 


The work on this project was supported by a Cooperative Agreement with the U.S. Centers for Disease Control and Prevention, Atlanta, Georgia.


The authors declare they have no actual or potential competing financial interests.


Received 18 July 2012; Accepted 24 October 2012; Online 25 October 2012.