Biomonitoring of per- and polyfluoroalkyl substances (PFAS) exposure in firefighters: Study design and lessons learned from stakeholder and participant engagement.

Firefighters may be occupationally exposed to per- and polyfluoroalkyl substances (PFASs) through Aqueous Film-Forming Foam (AFFF), smoke, dust and turnout gear, in addition to other background exposure sources. Epidemiological assessment of PFAS exposure in an occupational cohort of firefighting staff commenced in 2013-2014, following cessation of PFAS-based AFFF in Australian aviation. Here we present the study design and methodology of a follow-up study conducted in 2018-2019. We focus on our experiences engaging with stakeholders and participants with the establishment of an inclusive study group and highlight the key lessons learned from implementing a co-design process in the study. The study included a cross-sectional assessment of blood serum concentrations of 40 PFASs, including perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS), and 14 health-related biomarkers in 799 current and former Aviation Rescue Firefighting Services employees. A large proportion (87%) of the participants from the preliminary exposure study in 2013-2014 were re-recruited in the follow-up study. This enabled further longitudinal analyses in this subset of 130 participants. Participants included employees from different work roles and timeframes, reflecting the periods when three different firefighting foams were utilised in Australia. Establishment of a collaborative and inclusive study group (including stakeholders and participants) contributed to several components of the study design, including the expansion of robust analytical quality assurance and control measurements, and tailoring of communication and dissemination strategies. These outcomes were key factors that improved transparency of the research design, methods and results. Additionally, implementing elements of co-design helped build trust between researchers and participants, which is an important consideration for studies funded by stakeholders related to the exposure source.

Background release and potential point sources of per- and polyfluoroalkyl substances to municipal wastewater treatment plants across Australia.

Wastewater treatment plants (WWTPs) are known to be significant sources of per- and polyfluoroalkyl substances (PFAS) to the environment. In this study, PFAS were measured in the influent of 76 municipal wastewater treatment plants (WWTPs) serving approximately 53% of the Australian population. Of fourteen target PFAS, twelve analytes including six C5-C10 perfluoroalkyl carboxylic acids (PFCAs), four C4-10 perfluoroalkyl sulfonic acids (PFSAs) and two fluorotelomer sulfonates (6:2 and 8:2 FTS) were detected. Of these, PFOS, PFHxS and PFHxA had the highest median concentrations. The per capita background release of Σ12 PFAS to WWTP influent in Australia was estimated to be 8.1-24 µg/d/per person. The background release was supplemented by contributions from catchment specific point sources (i.e., industry, airports, military bases, and landfills), whereby the number of industrial sites positively correlated with the per capita mass load of Σ12 PFAS (r = 0.5-0.63, p < 0.01). The per capita mass loads were extrapolated to the entire Australian population, with estimates suggesting that approximately 1 kg/d of Σ12 PFAS reach WWTPs in Australia (300-400 kg annually), with more than half of the PFAS (∼59%) attributed to background release and the remaining (∼41%) to catchment specific point sources. These data provide insight into the release of major PFAS to wastewater at a national scale in Australia.

Trial of a novel experimental design to test depuration of PFASs from the edible tissues of Giant Mud Crab following exposure under natural conditions in the wild.

Poly and perfluorinated alkyl substances (PFASs) are persistent organic pollutants (POPs) that are highly resistant to environmental degradation, and have been detected in a broad range of terrestrial and aquatic species. Portunid crabs have been shown to accumulate comparatively high concentrations of PFASs, but previous work examining depuration in crabs was inconclusive. Here, we trialled a novel experimental design to study depuration of PFASs from edible tissues of portunid crabs, using paired claw samples, and trial this design with Giant Mud Crab Scylla serrata exposed to the contaminant under natural conditions. We found evidence for depuration of perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorooctanoic acid (PFOA), but with depuration half-lives as high as 40 days (for PFOS). We also observed substantial variability in the data, including differences in PFAS concentrations between claws from the same individuals, potentially resulting from claw loss and re-growth prior to capture. These results have broad implications for assessing and minimising exposure risk in seafood species.