Polybrominated Diphenyl Ethers, Occupational Exposures, and Thyroid Function Among US and Canadian Firefighters: A Cross-sectional Study.

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.