Chorioallantoic membrane of northern bobwhite (Colinus virginianus) as a nonlethal method for evaluating forever chemical exposure to avian offspring.

Per- and poly-fluoroalkyl substances (PFAS) are accumulative, persistent, and pervasive environmental contaminants known to cause adverse effects in wildlife after prolonged exposure. Oviparous species, particularly during their embryonic development stages, are highly susceptible to PFAS-related toxicity. Chronic exposure to these substances has been linked to bioaccumulation, resulting in arrested embryonic development, weakened immune responses, and reproductive defects in these animals. Traditional approaches, such as tissue chemical residue analysis, provide valuable insights into PFAS exposure but involve invasive methods, making them less viable for continuous monitoring. The chorioallantoic membrane (CAM) of bird embryos has emerged as a promising non-invasive alternative for detecting persistent pollutants. In this regard, CAM samples were collected from hatched northern bobwhite (NOBO) eggs derived from reproductive toxicity experiments where females were exposed to PFAS-contaminated drinking water over varying durations. In one experiment, females were exposed for 60 days to a fire suppression foam containing perfluorobutanoic acid and perfluorohexanoic acid, and the second experiment involved 90-day exposure to perfluorooctane sulfonic acid (PFOS) alone and a mixture of PFOS and perfluorohexane sulfonic acid. Liquid chromatography-mass spectrometry analysis revealed detectable but often unquantifiable levels of PFAS in CAM samples at low exposure concentrations. At higher exposure concentrations (20 ng/mL), yet still environmentally relevant, CAM analysis became more effective in providing an indication of PFAS exposure. These findings emphasize the potential utility of CAMs as a nonlethal method for assessing PFAS exposure in oviparous wildlife from certain scenarios and providing important insights into maternal transfer and transmembrane diffusion of PFAS from maternal tissue to hatchlings.