Bioaccumulation dynamics of perfluorooctane sulfonic acid (PFOS) and a binary mixture of PFOS and perfluorohexane sulfonic acid (PFHxS) in northern bobwhite (Colinus virginianus): a mini review

Abstract Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with significant bioaccumulation potential and toxicological concerns. Specifically, perfluorooctane sulfonic acid (PFOS) has been shown to reduce growth, reduce hatching success and decrease hatchling survivability, and arrest developmental cycles in birds. While the transfer of PFAS from exposed adult birds to their offspring is recognized, the routes of maternal transfer are not yet fully elucidated. Therefore, this mini review synthesizes previously collected. PFAS tissue residue data from a series of chronic toxicity studies in Northern bobwhite (NOBO) conducted in our laboratory, integrating findings from adult tissues, whole eggs, the chorioallantoic membrane (CAM), and hatchling tissues. Our goal was to provide a better understanding of tissue-specific PFAS bioaccumulation in the adult, and maternal transfer to the developing chick. The available data revealed that the liver serves as the primary site for PFAS bioaccumulation in adult and hatchling NOBO, following the trend: adult liver > adult brain > post-hatch CAM > whole egg > hatchling liver > hatchling brain. Hatchling tissues exhibited lower PFAS concentrations in brain and in liver compared to those same tissues in adult females; hatchlings received PFAS exposure only through maternal transfer during embryonic development. The data from our studies further highlight that assessing the post-hatch CAM, rather than the whole egg, is important because it serves as a direct link between the embryo and the egg’s internal environment, thus reflecting a PFAS burden that is available to the developing chick; whole egg measurements capture total PFAS deposited by the female NOBO into the egg. Findings from controlled PFAS exposures to birds conducted in our laboratory indicate that maternal PFAS burdens influence hatchling exposure and contribute to PFAS bioaccumulation patterns.