Organophosphate and organohalogen flame-retardant exposure and thyroid hormone disruption in a cohort of female firefighters and office workers from San Francisco

Abstract

Background: Occupational exposures to flame retardants (FR), which are suspected endocrine disrupting compounds, may be of particular concern for firefighters as they are commonly found in consumer products and have been detected in fire station dust and firefighter gear. Objectives: The Women Workers Biomonitoring Collaborative is a community based participatory research study that sought to measure environmental chemicals relevant to firefighting and evaluate their effects on thyroid hormone levels. Methods: We measured 10 FR or their metabolites in urine of female firefighters and office workers 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), 5-OH-BDE 47, and 5-OH-BDE 100. We assessed potential predictors of exposure levels and the association between FR exposures and thyroxine (T4) and thyroid stimulating hormone (TSH). Results: BDCPP, BCEP, and DBuP were the most commonly detected FRs, among all study participants, with intermediate BMI and college educated women having the highest levels, and Black women having higher BDCPP levels than White women. Firefighters had higher detection frequencies (DF) and exposure levels compared to office workers; median BDCPP levels were five times higher in firefighters than in office workers. Among firefighters, occupational activities were not significantly associated with FR levels, although position (i.e. officer and firefighter versus driver), being on-duty (versus off-duty) and assigned to the airport suggested a positive association with FR levels. Among firefighters, a doubling of BDCPP was associated with a 2.88% decrease (95%CI -5.28,-0.42) in T4. We did not observe significant associations between FR and T4 among office workers. Discussion: Firefighters had significantly higher exposures to FR compared to office workers, and we observed a negative association between BDCPP and thyroxine in firefighters. Future research should elucidate occupational sources of FR exposure and opportunities for exposure reduction.

Associations between polyfluoroalkyl substance and organophosphate flame retardant exposures and telomere length in a cohort of women firefighters and office workers in San Francisco

“…Descriptive statistics of flame retardant data revealed disparate distributions of chemical concentrations between occupational groups, with firefighters’ concentrations measured at higher detection frequencies and higher concentrations relative to office workers ( Table 1 and Additional file 3 ). A more in-depth description of the differences in flame retardant concentrations between occupational groups and associated covariates is discussed in Trowbridge et al, 2020 (68). In brief, BDCPP, BCEP, DBuP, and DpCP were all measured at significantly higher levels among firefighters compared to office workers ( Table 1 and Additional file 3 ).…”

“…Few covariates were associated with flame retardant metabolites within this population(68). Age was included in all models as well as log-transformed creatinine (logCreatinine) to account for differences in urine dilution(97).…”

Associations between polyfluoroalkyl substance and organophosphate flame retardant exposures and telomere length in a cohort of women firefighters and office workers in San Francisco

“…Few covariates were associated with flame retardant metabolites within this population [ 68 ]. Age was included in all models as well as log-transformed creatinine (logCreatinine) to account for differences in urine dilution [ 99 ].…”

“…Firefighters are also exposed to hazardous chemicals in fire station dust, diesel exhaust, firefighting foams, contaminated fire equipment, and certain firefighting gear [ 54 – 59 ]. Studies have documented firefighters’ exposure to benzene, polycyclic aromatic hydrocarbons (PAHs), formaldehyde, dioxins, polybrominated diphenyl ethers (PBDEs), polyfluoroalkyl substances (PFAS), and organophosphate flame retardants (OPFRs) [ 60 – 68 ].…”

“…Firefighters are also occupationally exposed to flame retardants [ 65 , 68 , 80 ]. While use of polybrominated diphenyl ether (PBDE) flame retardants in consumer products has been gradually phased out due to their toxicity to humans, persistence in the environment, and ability to bioaccumulate [ 81 ], OPFRs and other halogenated flame retardants have emerged as replacements and have been found in fire stations [ 82 – 84 ].…”