Toxicities of Legacy and Current Use PFAS in an Anuran: Do Larval Exposures Influence Responses to a Terrestrial Pathogen Challenge
Per-and polyfluoroalkyl substances (PFAS) are a large group of emerging contaminants that include astrong carbon-flourine bond that makes the compounds resistant to physical, chemical and biological degradation. They are found in drinking water supplies, daily human products, manufacturing facilities, and in areas where aqueous film-forming foam (AFFF)was used to extinguish fires. Toxicity levels of these chemicals can vary depending on the characteristics of the specific chemical; longer carbon chain has shown to be more bioaccumulative and toxic than shorter chain length PFAS. Many studies have recognized perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) to be a substantial concern due to their known toxicity to wildlife. For example, studies show strong evidence that PFOA and PFOS suppress the antibody response from animals. Due to adverse health effects and public concern, the U.S stopped perfluorooctanoic acid (PFOA) manufacturing and switched to the production of an alternative fluorinated compound known as hexafluoropropylene oxide (HFPO) dimer acid or GenX, which is thought to beless bioaccumulative and therefore, potentially less toxic. These anthropogenic pollutants are one of many stressors acting on aquatic organisms like anurans. Natural stressors such as the devastating fungal pathogen Batrachocytrium dendrobatidis(Bd) is another stressor impacting amphibian populations. Despite the co-occurrence of these stressors, no studies have examined interactive effects of the fungal pathogen Bd and PFAS, or whether PFAS effects carry over into the terrestrial environment aftera larvae exposure. This study tested the growth and developmental effects of PFOS, PFOA, and GenX, on gray treefrog (Hyla versicolor) tadpoles, followed by a Bd challenge in metamorphs. Our results demonstrate that a PFAS larval exposure interacted witha terrestrial Bdchallenge to influence growth and development. Bdexposed animals were significantly shorter (smaller snout vent length) and had a significant increase in body condition and mass. This is the first study to report effects on amphibian terrestrial life stages after larval exposure to PFAS and to report an increased sensitivity to Bd. The environmentally relevant concentrations tested in this study (<10 parts per billion) lend ecological significance to these results however, additional studies are needed to understand the mechanisms behind these effects.