Wide scope screening and target quantification of per- and polyfluoroalkyl substances (PFAS) in feed and feed...

Fish meal (FM) is a recognized source of per- and polyfluoroalkyl substances (PFAS) in aquafeeds and following farmed seafood. Targeted determination and non-target wide scope screening was combined with total oxidizable precursor (TOP) assay in both marine- and plant-based feed ingredients used in farmed Atlantic salmon feed to Norwegian Atlantic salmon to assess pattern and source of PFAS contamination in the salmon seafood production chain. Of all main feed ingredients, FM had highest PFAS loads with 12 detected PFAS of which PFUnDA and PFOS as the dominant compounds (mean 0.34 and 0.32 µg kg⁻¹wet weight, respectively). Other feed ingredients, including fish oil (FO), plant oil (PO), and plant meal (PM), generally contain lower PFAS levels. However, PFOS was detected in all FO and PO samples, and as salmon feed contains mainly (>70 %) plant ingredients, they can significantly contribute to overall PFAS load in feed. More importantly, salmon feed contained high levels of PFAS precursors, at concentrations by far (up to two-fold) exceeding the legacy PFAS. As these precursors can be transferred into legacy PFAS, as confirmed by the TOP assay, the presence of these precursors can "mask" additional source and loads of PFAS in farmed salmon.