Sources and pathways of PFAS exposure in firefighter residential environments

In Australia, the use of per- and polyfluoroalkyl substances (PFAS) in firefighting foams ceased in 2014, yet traces remain in fire stations. Given the large amount of time spent in fire stations by on-duty firefighters, these areas are effectively residential environments. Given the known toxicity and adverse health effects of PFAS, we aim to determine the level of PFAS that firefighters continue to be exposed to and whether this exposure is from residual PFAS inside the fire stations or tracked indoors from outdoors. We also examined exposures to trace metals, asbestos and elemental and organic carbon. We analysed dust samples (indoors) and soil samples (outdoors) from 45 fire stations in Melbourne, Australia, to determine contaminant exposures and indoor-outdoor relationships. We also compared these to dusts and soils from residential properties in Melbourne and Sydney, Australia. Dust samples from 44 of 45 fire stations exceeded the Australian residential PFOS investigation level of 0.01 mg/kg, with 39 also exceeding PFHxS investigation levels of 0.01 mg/kg. Dust from one fire station also exceeded the Residential B soil investigation levels for PFOS (2 mg/kg). Chromium (Cr) was the only metal exceeding Australian Residential A soil criteria, exceeding in 12 of 45 stations in dust and 6 of 45 stations for soil. No asbestos was found and no relevant standard was available for comparison of carbon components. The higher average dust concentrations of PFAS-type compounds in fire stations compared to Melbourne and Sydney homes corresponds with the likelihood that contamination has arisen from extensive past use of PFAS by the firefighters as part of their standard occupational activities. Similarly, elemental carbon concentrations were higher for fire stations, suggesting fire engine exhaust as a source. Dust PFAS and metals contaminant concentrations were not related to soil contaminant concentrations for the same property, hence this indoor contamination is residual and not being tracked inside from outdoors. More thorough cleaning activities and investigation of potential additional sources are required to remove PFAS and metals from indoor fire station environments.