Do flame retardants increase risk of thyroid disease?
Women who have been exposed to polybrominated diphenyl esters (PBDEs)—common chemicals used as flame retardants—may have a higher risk of thyroid disease, according to results of a study in Environmental Health. The association may be enhanced, the authors said, by the altered estrogen levels in menopause.
To test the association between the chemicals and thyroid disease in women, the researchers used serum PBDE concentrations for BDEs 47, 99, 100, and 153, which were part of the National Health and Examination Survey (NHANES) and reports on thyroid problems, which had been a part of the NHANES 2003-2004 cycle. Multivariate logistic regression models were used to calculate odds ratios (ORs), while controlling for thyroid medication, alcohol consumption, smoking, education, age, and body mass index. Menopause status was identified using self-reported absence of menstruation in the previous 12 months.
Women who were in the highest quartile of BDE 47, 99, and 100 exposure showed increased odds of currently having thyroid disease (ORs: 1.5, 1.8, 1.5, respectively) when compared to those who were in the first and second quartiles combined. When the analysis was restricted to just postmenopausal women, the association was stronger (ORs: 2.2, 3.6, 2.0, respectively).
The researchers concluded that exposure to BDEs 47, 99, and 100 can increase the risk of thyroid disease. As for the stronger association in postmenopause, they hypothesized that the change in estrogen levels during menopause may disrupt thyroid signaling by PBDEs. The authors suggested additional research to confirm their findings, particularly when new NHANES data become available.