Occurrence of per- and polyfluoroalkyl substances, pesticides, pharmaceuticals, and heavy metals in Greek backyard chicken eggs and estimation of the consumption risk

Backyard chicken eggs are widely consumed worldwide, while they are also used as pollution bio-indicators for different groups of chemicals. In this study, home-produced eggs were collected from 17 chicken coops around Greece and analyzed for 46 per- and polyfluoroalkyl substances (PFAS), heavy metals, pesticide, and pharmaceutical residues. The number of PFAS detected per sample ranged from 17 to 24, while the mean concentration of Σ₄₆PFAS was 7.67 μg/kg ww. Perfluoroalkyl carboxylic acids contributed to 43 % of the total concentration, followed by perfluoroalkyl sulfonic acids (26 %) and perfluoroalkanelsulfonamides (16 %). Polyfluoroethercarboxylic acids, polyfluoroethersulfonic acids, and perfluoro alkyl phosphonic acids were detected occasionally and at low concentrations. Concerning the occurrence of individual PFAS, the highest mean concentrations were detected for PFOS (0.996 μg/kg ww), PFHxS (0.799 μg/kg ww), and PFBA (0.742 μg/kg ww). LC-QTOF-MS analysis indicated the co-presence of 6 pesticides and 5 pharmaceuticals in collected samples. Among pesticides, dinoterb and N,N-diethyl-m-toluamide (DEET) were found in all samples. DEET had the highest average concentration (8.25 μg/kg ww). Oxolinic acid was the most often detected pharmaceutical, with an average concentration of 1.03 μg/kg ww. The concentrations of heavy metals were low, and did not pose a threat to public health. In contrast, significant health concerns were raised due to the presence of PFAS, only 8 out of 17 samples were compliant to the limit set by the EU for eggs, while the mean PFAS weekly intake through eggs for adolescents and elderly exceeded EFSA's tolerable weekly intake.