Analysis of per- and polyfluoroalkyl substances (PFASs) in soil from Swedish background sites

Per- and polyfluoroalkyl substances (PFASs) are persistent organic pollutants with bioaccumulative and toxic potential. This study investigated the levels, composition profiles and geographical distribution of 28 PFASs in 31 soil samples from Swedish background areas. In total, 15 of the 28 analysed PFASs were detected, with an average concentration of 2.4 ng g-1 dw (median of 1.9 ng g-1 dw, n = 31). The dominant PFASs in the soil samples were perfluorooctane sulfonic acid (PFOS) (20 % of the ∑28PFASs), perfluorooctane sulfonamidoacetic acid (FOSAA, 15 %), 6:2 fluorotelomer sulfonic acid (6:2 FTSA, 14 %) and perfluorobutane sulfonic acid (PFBS, 13 %). Perfluorooctane sulfonic acid (PFOS) had also the highest detection frequency of the studied PFASs (77 %) in the soil samples with a median concentration of 0.30 ng g-1 dw. However, the guideline value for PFOS in soil for sensitive land use from the Swedish Geotechnical Institute (SGI) (3 ng g-1 dw) was not exceeded in any sample. However, assuming the same toxicity for all PFASs, the ∑28PFAS concentrations exceeded the guideline value (3 ng g-1 dw) in 9 out of 31 samples (29 %). PFOS and perfluoroundecanoic acid (PFUnDA) concentrations showed higher concentrations towards the south (significant negative correlation with latitude; p