Per- and polyfluoroalkyl substances (PFAS) and heavy metals in the egg of peregrine falcon (Falco peregrinus) populations in West England, United Kingdom

Per- and polyfluoroalkyl substances (PFAS) are a wide range of substances applied to many kinds of industrial and commercial usages. The PFAS contamination in marine or shore birds has been largely studied, whereas research on terrestrial predatory birds remains limited. Populations of the peregrine falcon ( Falco peregrinus ) recently decline on the North Cornish coast, United Kingdom (UK), despite a decreasing trend in environmental legacy organic contaminants. Exposure to PFAS is suspected to be contributed to one of the causes of this decline, but the knowledge on PFAS exposure of UK wild birds is still poor. To assess the current PFAS exposure of UK terrestrial predatory birds and potential effects of PFAS on the breeding success of peregrines, we have measured the PFAS burden in peregrine eggs from different England counties and compared PFAS in eggs with stable isotopes and the eggshell index. Our results showed that long-chain perfluoroalkyl acids were predominantly detected in peregrine eggs, and perfluorooctanoic acid (PFOA) and perfluorohexanesulfonic acid (PFHxS) residues differed among UK counties. PFAS residues in eggs correlated with δ ¹³ C and δ ³⁴ S but not δ ¹⁵ N, which means that the variation in the diet may be a more important factor than trophic level impacting peregrine exposure to PFAS. Meanwhile, no significant relationship was observed between eggshell index and PFAS residues, meaning that PFAS might not result in the egg thinning. However, the knowledge about the adverse effects of PFAS on the bird population is still limited, and further studies filling such knowledge gaps are needed.