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Flame-retardant exposure may increase hypothyroidism risk
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Exposure to polybrominated diphenyl ethers may be associated with an increased prevalence of hypothyroidism in women aged 30 to 50 years, according to recent findings.
Researchers evaluated 745 women enrolled in the Canadian Health Measures Survey (cycle 1, 2007-2009), a sampling survey intended to generate estimates representing the Canadian population aged 6 to 79 years. Researchers limited their focus to women aged 30 to 79 years with available measurements of polybrominated diphenyl ethers (PBDEs) for the present study. Information about hypothyroid status was gleaned directly through interviews with study participants. Cases (n = 90) were identified based on self-report of a physician-diagnosed thyroid condition and the use of thyroid hormone replacement. Nine PBDE congeners were measured (BDE-15, 17, 25, 28, 33, 47, 99, 100 and 153), as well was polychlorinated biphenyl-153.
After adjustment for age, income, education, race/ethnicity, breast-feeding history and alcohol consumption, researchers found a positive correlation between blood PBDE concentration and the rate of hypothyroidism. For each 10-fold increase in (summation)PBDE and BDE-47, there was a 70% increase in the prevalence of hypothyroidism ([summation]PBDE, prevalence ratio [PR] = 1.7; 95% CI, 1-3; BDE-47, PR = 1.7; 95% CI, 1-2.9).
Participants with detectable levels of BDE-100 had significantly higher rates of hypothyroidism vs. participants without detectable levels (PR = 1.8; 95% CI, 1-3.3).
Hypothyroidism was not found to be associated with BDE-99 or 153 congeners.
The associations were found to be significantly higher for (summation)PBDE and the other PBDE congeners among participants aged 30 to 50 years vs. those aged 51 to 79 years, although this interaction reached significance only for BDE-100 (P = .09). In the younger cohort, participants with detectable BDE-100 levels had a PR of 3.8 (95% CI, 1.2-12.2) vs. participants without detectable levels.
“We report in this population-based study an increased prevalence of hypothyroidism in association with plasma PBDE concentrations,” the researchers wrote. “We also found stronger associations among younger women compared to older women. These findings may have important implications given the key role of thyroid hormones in several biological mechanisms.” – by Jennifer Byrne
Disclosure: The researchers report no relevant financial disclosures.
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