Ecosurveillance reveals subtle metabolic effects on the non-native cane toad (Rhinella marina) from low levels of accumulated environmental per- and polyfluoroalkyl substances

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals that persist in the environment, bioaccumulate, and may have toxic effects. This study used non-native cane toads (Rhinella marina) to examine PFAS and metal accumulation and impacts in large terrestrial amphibians from urban and peri-urban areas. We quantified 38 PFAS compounds and 36 environmental and legacy metal(loid)s in 52 adult cane toad livers collected from six locations around Southeast Queensland, Australia, along a known PFAS gradient. Associations among PFAS, metal(loid) concentrations, and whole-organism metrics were assessed. An omics-led approach assessed biochemical responses in liver, muscle, fat and gonad/egg tissues associated with these PFAS concentrations. Liver PFAS concentrations ranged from 0.5 to 82.1 μg/kg ww, with one male outlier at 452 μg/kg ww (mean: 18 ± 21 SD μg/kg ww, excluding outlier). PFOS was the most dominant PFAS (60 ± 26 SD% of total), followed by PFDoDA (13 ± 9 SD%). The liver metal(loid)s with statistically significant variation among locations and sex were Al, As, Ca, Cu, Mn, Ni, Se, Sn, Sr and V. Total PFAS had no associations with whole-organism metrics, and body condition and relative femur length showed a weak interaction effect between PFAS and Ni. Metabolic profiling revealed sex-specific differences linked to total PFAS, with females showing a broader metabolic perturbation. The strongest metabolic signals were in glycerolipid metabolism, ether lipid metabolism, and fatty acid biosynthesis, though these effects were statistically weak. PFAS and metal(loid) levels were low compared to those previously recorded in tertiary consumers and aquatic vertebrates from contaminated areas. Despite minor metabolomic changes, the overall health impact was minimal. These findings contribute to the development of tissue PFAS guideline values for wild amphibians, but further studies on higher PFAS levels of accumulation and responses of additional amphibian species are needed.