Organophosphate and organohalogen flame retardant exposure and thyroid hormone disruption in women firefighters and office workers from San Francisco

Abstract

BACKGROUND AND AIM: Organophosphate flame retardants (OPFR) are suspected endocrine disrupting compounds and have been detected in fire station dust and firefighter gear. Studies have reported that exposure to FRs can disrupt thyroid hormone (TH) function; however, this relationship is not well characterized, especially for halogenated OPFRs. TH is important for thyroid mediated gene expression and may be relevant to adverse health effects such as cardiovascular disease and cancer. We describe OPFR exposure and its association with TH levels in a cohort of women firefighters and office workers from San Francisco. METHODS: Using liquid chromatography-tandem mass spectrometry (LC MS/MS), we measured 8 urinary FR metabolites in female firefighters (N=86) and office workers (N=84) from San Francisco: bis(1,3-dichloro-2-propyl) phosphate (BDCPP), bis(2-chloroethyl) phosphate (BCEP), dibutyl phosphate (DBuP), dibenzyl phosphate (DBzP), di-p-cresyl phosphate (DpCP), di-o-cresyl phosphate (DoCP), 2,3,4,5-tetrabromobenzoic acid (TBBA), tetrabromobisphenol-A (TBBPA). We assessed potential predictors of exposure levels and the association between FR exposures and thyroxine (T4) and thyroid stimulating hormone (TSH) for 84 Firefighters and 81 office workers. RESULTS:BDCPP, BCEP and DBuP had the highest concentrations among all study participants. However, firefighters had higher median exposure levels of BDCPP, BCEP and DBuP compared to office workers. When we assessed the association of each FR with TH we found that a doubling of BDCPP was associated with a 2.88% decrease (95%CI -5.28,-0.42) in T4 among firefighters. We did not observe significant associations between FR and T4 among office workers nor between FR and TSH in either firefighters or office workers. CONCLUSIONS:Firefighters had significantly higher exposures to FR compared to office workers and their exposure to BDCPP was associated with TH disruption. Characterizing exposure to endocrine disrupting chemicals and assessing the association with biomarkers of early effect such as TH can inform prevention efforts without having to wait for adverse health outcomes to occur. KEYWORDS: occupational exposures, women firefighters, endocrine disruption