Polybrominated Diphenyl Ethers, Occupational Exposures, and Thyroid Function Among US and Canadian Firefighters

Objective Evaluate the association between serum polybrominated diphenyl ether (PBDE) levels and thyroid anatomy and function in firefighters. Methods Two hundred fifty-nine firefighters provided a blood sample and underwent thyroid ultrasound. Blood serum levels were tested for thyroid function tests and PBDEs -47, -85, -99, -100, -153, and -154 (ng/g lipid weight). Ultrasonography documented structural characteristics. Bivariate associations between PBDE concentrations and demographic/occupational characteristics, thyroid function, and thyroid anatomic measures were determined using multivariable linear regression. Results A positive relationship between PBDE-47 and triiodothyronine ( P = 0.02) while an inverse relationship with free thyroxine ( P = 0.03) was observed. PBDE-47 was inversely associated with thyroid nodule size ( P = 0.03) and nodule aggressiveness ( P = 0.02). PBDE-47 was highest in western United States firefighters and lowest among sampled Canadians ( P = 0.01). Conclusions PBDE-47 may contribute to thyroid dysregulation in firefighters. PBDE-47 levels differ across North America.