Accumulation of per- and polyfluoroalkyl substances (PFAS) in a terrestrial food web

Per- and polyfluoroalkyl substances (PFAS) are synthetic organofluorine chemical compounds that are broadly used in amongst others aqueous firefighting foam, cosmetics, textiles, carpets, coatings, plastics, and ski wax. Their chemical properties make them persistent organic pollutants that are potential bioaccumulative and toxic. Most studies on PFAS have been performed in groundwater, surface water and aquatic biota. Our knowledge on the terrestrial fate of PFAS is therefore limited. We sampled soil, berries, mushrooms, and wildlife on the island Froson, central Sweden, in 2021 and 2022, to study the fate of 22 PFAS in a terrestrial food web. Groundwater, surface water and fish on Froson have previously shown high PFAS concentrations. Soil, berries, and mushrooms were also concurrently sampled in a reference area in northern Sweden. Overall, concentrations of the sum of PFAS were low in berries and mushrooms. In moose (Alces alces), roedeer (Capreolus capreolus), and bank vole (Myodes glareolus), concentrations were highest in liver. The maximum levels for PFOS in offal as set by the European Commission (50 ng/g ww) were exceeded in the liver of two of 10 roedeer. Bank voles (n = 12 pools) that were sampled in the vicinity of a firefighting training site showed partly extreme concentrations with none of the samples having liver concentrations <474 ng/g ww (maximum 11,600 ng/g ww). Bioaccumulation factors (BAFs) for multiple PFAS in bank voles were higher for the studied mushrooms and soil compared to studied berries and were >100 for 27 out of 265 calculated BAFs. BAFs in the ungulate species were generally lower than those for bank voles but were >1 for several PFAS from the mushroom. The exact origin of PFAS in bank voles could not be identified in our study, but the BAFs are supported by the feeding and behaviour ecology of bank voles, i.e., there is likely bioaccumulation and biomagnification from soil and mushrooms to bank voles. The measured PFAS concentrations and BAFs, especially those in bank voles are worrying from an ecosystem and One Health perspective considering that voles are staple food for multiple predators.