Stone, M. B., Stanford, J. B., Lyon, J. L., VanDerslice, J. A., & Alder, S. C. (2013). Childhood thyroid radioiodine exposure and subsequent infertility in the intermountain fallout cohort. Environmental health perspectives, 121(1), 79-84. https://doi.org/10.1289/ehp.1104231
Stone MB, Stanford JB, Lyon JL, VanDerslice JA, Alder SC. Childhood thyroid radioiodine exposure and subsequent infertility in the intermountain fallout cohort. Environ Health Perspect. 2013;121(1):79-84. doi:10.1289/ehp.1104231
Stone, Mary Bishop, et al. "Childhood thyroid radioiodine exposure and subsequent infertility in the intermountain fallout cohort." Environmental health perspectives, vol. 121, no. 1, 2013, pp. 79-84.
Childhood fallout radioiodine was possibly linked to adult infertility
Childhood exposure to radioiodine from nuclear test fallout was possibly linked to adult infertility, in an exploratory study of 1,389 people. The highest dose group had somewhat higher odds of infertility, with a wide margin of error. Sterility showed no link.
Key Findings
The analysis covered 1,389 people with dose estimates and a known fertility history. Researchers classed 274 as infertile, and 30 of those as sterile.
Adjusted odds ratios for infertility, against the lowest dose tertile, were 1.17 (95% CI: 0.82, 1.67) for the middle and 1.35 (95% CI: 0.96, 1.90) for the upper.
After adjusting for medically confirmed thyroid disease, the odds ratios were 1.08 (95% CI: 0.75, 1.55) and 1.29 (95% CI: 0.91, 1.83).
Thyroid disease itself carried an adjusted odds ratio for infertility of 1.78 (95% CI: 1.13, 2.82).
Sterility showed no association with dose. The adjusted odds ratios were 1.02 (95% CI: 0.35, 2.94) for the middle tertile and 1.11 (95% CI: 0.42, 2.87) for the upper.
Interpretation
The authors call this an exploratory analysis. All the confidence intervals for the tertile comparisons include 1.0, so the results show a possible association and cannot show cause. Infertility was self-reported from memory and defined as a year or longer of trying. Doses were estimated from parents' recall of milk and vegetable intake. Follow-up ended early when funding ran out, so 1,596 of the original 4,818 schoolchildren returned questionnaires. Among the quartiles, the third showed a clear association (AOR 1.62, 95% CI: 1.09, 2.41) and the fourth did not (AOR 1.27, 95% CI: 0.85, 1.90). The authors ask for confirmation in the full cohort and in other exposed groups.
RRM Context
Restorative reproductive medicine treats infertility as a symptom with a cause to find. Exposure history is one place a cause can hide. In this cohort, medically confirmed thyroid disease was itself a risk factor for infertility. The cohort came from three counties near the Nevada Test Site, exposed to fallout from 1950s above-ground testing.
Our editorial summary of this paper, not the article's abstract.
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.
03r0ha626 