Concerns about per- and polyfluoroalkyl substances (PFAS) stem from their ubiquitous presence in the environment, persistence, and variable/uncertain bioaccumulation and toxicity. The reproductive and developmental effects of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been widely evaluated in inbred and outbred laboratory rodents. This project was designed to evaluate potential reproductive and developmental effects of various PFAS in wild mice.
This project involved two key tasks: to demonstrate that exposure was stable during common toxicity test timelines and to perform toxicity tests spanning sensitive life stages.
Five legacy PFAS and one next-generation PFAS were administered to white-footed mice (Peromyscus leucopus) to elucidate if plateaus in serum concentrations were reached following 28 days. Blood samples from multiple timepoints were analyzed for individual PFAS concentrations via liquid chromatography-tandem mass spectrometry (LC-MS/MS).
Then, Peromyscus were exposed orally to one of four chemicals (PFOS, perfluorononanoic acid (PFNA), perfluorohexane sulfonate (PFHxS), or 6:2 fluorotelomer sulfonate (6:2 FTS)) for 28 consecutive days. Exposure continued for an additional 12 weeks, during which animals were allowed to breed. Toxicity data in males, females, and offspring were used to derive toxicity thresholds for Peromyscus via benchmark dose modeling.
Endpoints affected by four PFAS in Peromyscus are largely consistent with studies previously conducted in inbred and outbred rats and mice. Specifically, prenatal exposure to high doses of PFOS caused neonatal mortality. Prenatal exposure to PFHxS caused increased stillbirths and reduced immune response. At the doses tested, PFNA and 6:2 FTS did not markedly affect reproduction or development, but these experiments suggest they reduce immune response in Peromyscus. Finally, Peromyscus exposed to perfluoroalkyl acids (PFAAs), but not 6:2 FTS, exhibited decreased serum thyroid levels and increased liver weights.
Although many toxicity tests have been done with traditional laboratory species, few comprehensive tests for any PFAS have been undertaken with wild mammalian species. Data from this project support previously identified toxicity endpoints and provide new information about PFHxS and 6:2 FTS, which are highly relevant at aqueous film forming foam (AFFF)-impacted DoD sites. Toxicity data from this series of experiments can be used to develop toxicity reference values (TRVs), which are critical components of risk assessments. (Anticipated Phase II Completion – 2024)
Bohannon, M.E., A.M. Narizzano, B.G. Guigni, A.G. East, M.J. Quinn, Jr. 2023. Next-Generation PFAS 6:2 Fluorotelomer Sulfonate Reduces Plaque Formation in Exposed White-Footed Mice. Toxicological Science, 192(1):97-105. doi.org/10.1093/toxsci/kfad006.
Narizzano, A.M., E.M. Lent, J.M. Hanson, A.G. East, M.E. Bohannon, M.J. Quinn, Jr. 2022. Reproductive and Developmental Toxicity of Perfluorooctane Sulfonate (PFOS) in the White-Footed Mouse (Peromyscus leucopus). Reproductive Toxicology, 113:120-127. doi.org/10.1016/j.reprotox.2022.08.011.
Narizzano, A. M., M. E. Bohannon, A. G. East, C. McDonough, S. Choyke, C. P. Higgins, and M. J. Quinn. 2021. Patterns in Serum Toxicokinetics in Peromyscus Exposed to Per- and Polyfluoroalkyl Substances. Environmental Toxicology and Chemistry, 40(10):2886-2898. doi.org/10.1002/etc.5151.
Narizzano, A.M. 2020. Development and Application of Vertebrate Models to Investigate the Risk of Defense-Relevant Chemicals (Ph.D. Dissertation). University of Maryland, Baltimore.