Per- and polyfluoroalkyl substances (PFAS)

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Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic (human-made) chemicals valued for their resistance to water, oil, grease, and stains. These colorless, odorless, and highly stable compounds are found in a wide variety of products, including nonstick cookware, food packaging, cleaning products, cosmetics, plastics, electronics, water-repellent textiles, and firefighting foams.1

PFAS do not easily break down when released into the environment and can build up in body tissues over time, posing risks to both human and animal health. In animals, PFAS exposure has been linked to health issues such as liver damage, immune system suppression, and developmental problems.2 There are no known treatments for exposure in any species, so the best way to mitigate their effects on animal, public, and ecosystem health is to minimize exposure.

For these reasons and more, it's important that veterinarians understand the sources, exposure routes, and potential hazards of PFAS.

Where do PFAS come from?

PFAS are primarily released from manufacturing and industrial processes. Because they resist degradation, PFAS persist in the environment and can spread through water, soil, and air, leading to widespread contamination—even in remote ecosystems.

How are animals exposed to PFAS?

Animals can be exposed to PFAS through multiple pathways.

Water

Contaminated water can be a major source of exposure. PFAS can enter water supplies through runoff from manufacturing plants and other industrial facilities, landfills, and agricultural sites treated with biosolids or pesticides. Wildlife and aquatic animals (both wild and farmed) are especially vulnerable.

Diet

Plants can absorb PFAS from contaminated soil or water, introducing these chemicals into the food chain. Herbivores may ingest contaminated vegetation, and carnivores can be exposed through prey in which PFAS have bioaccumulated. These compounds can biomagnify, increasing in concentration further up the food chain.

Environment

Animals—whether livestock, wildlife, or companion animals—can encounter PFAS directly through contact with contaminated soil or indirectly via wind-blown particles, surface runoff, or groundwater. Animals kept indoors may be exposed via household items like carpets, upholstery, or even food and medication packaging.3

How can PFAS affect animal health?

Our understanding of how PFAS may affect animal health is largely derived from toxicological studies as well as epidemiologic evidence in people. For people, PFAS have been linked to immune suppression (including vaccine inefficacy), increased cholesterol, reproductive issues, developmental disorders, increased risk of certain cancers, and other adverse health outcomes.

The available evidence suggests pets and other animals likely are susceptible to harmful effects from PFAS, although more studies are needed to determine the nature and frequency of these effects. Guidelines also are needed for interpreting results for animals of various standardized testing methods for PFAS.

Pets

Exposure to PFAS has been linked to elevated liver enzymes, cholesterol, and thyroid hormones in dogs and cats.4,5 Preliminary evidence also suggests that hyperthyroidism may be associated with greater total serum PFAS concentrations in cats.5

Fish

Most research on PFAS in fish has been focused on potential risks to people through fish consumption. The compounds accumulate in fish through both water and dietary exposure (bioaccumulation through the food chain). They have been found in various tissues, including whole body, muscle, blood, and liver samples, with highest concentrations found in blood and liver tissue.6,7 Surveillance work is underway by federal and state agencies to better understand tissue PFAS concentrations in fish and what they may mean for human health.8

Livestock

PFAS have been detected in the serum, liver, kidneys, and milk of farm animals including chickens, cattle, pigs, goats, and horses.9,10 There also have been anecdotal reports of bovine mortality following exposure to contaminated water.11 Besides the possible impacts of PFAS on the animals, food products derived from affected animals may pose an exposure pathway for people.

Wildlife

PFAS have been demonstrated in the tissues of multiple wildlife species worldwide, including in remote regions like the Arctic. The highest concentrations in wildlife are associated with proximity to PFAS-contaminated sites.

In terms of specific animals, elevated PFAS levels have been associated with an increased incidence of disease in sea otters,12 increased risk of disease in dolphins,13 decreased foraging behavior in crayfish,14 reduced hatching success in sea turtles,15 and autoimmune conditions in alligators.16

Have questions?

Email PFASatavma [dot] org with comments or questions about PFAS and how they relate to veterinary medicine.

References

1. Brake HD, Langfeldt A, Kaneene JB, Wilkins MJ. Current per- and polyfluoroalkyl substance (PFAS) research points to a growing threat in animals. J Am Vet Med Assoc. 2023;261(7):952-958. doi:10.2460/javma.22.12.0582
2. US Department of Health and Human Services. Toxicological profile for perfluoroalkyls. Accessed June 20, 2025. https://www.atsdr.cdc.gov/toxprofiles/tp200.pdf
3. Public Employees for Environmental Responsibility. Flea-control products found to be infested with forever chemicals. Accessed June 20, 2025. https://peer.org/flea-control-products-found-to-be-infested-with-forever-chemicals/
4. You D, Chang X, Guo L, et al. Per- and polyfluoroalkyl substances (PFASs) in the blood of police and Beagle dogs from Harbin, China: concentrations and associations with hematological parameters. Chemosphere. 2022;299:134367. doi:10.1016/j.chemosphere.2022.134367
5. Wang M, Guo W, Gardner S, Petreas M, Park JS. Per- and polyfluoroalkyl substances in Northern California cats: temporal comparison and a possible link to cat hyperthyroidism. Environ Toxicol Chem. 2018;37(10):2523–2529. doi:10.1002/etc.4239
6. Nilsen E, Muensterman D, Carini L, et al. Target and suspect per- and polyfluoroalkyl substances in fish from an AFFF-impacted waterway. Sci Tot Environ. 2025;906167798. doi:10.1016/j.scitotenv.2023.167798
7. Barbo N, Stoiber T, Naidenko OV, Andrews DQ. Locally caught freshwater fish across the United States are likely a significant source of exposure to PFOS and other perfluorinated compounds. Environ Res. 2023;220:115165. doi:10.1016/j.envres.2022.115165
8. US Environmental Protection Agency. EPA releases new science-based recommendations to help more states, tribes, and territories reduce exposure to PFAS in fish. Accessed June 20, 2025. https://www.epa.gov/newsreleases/epa-releases-new-science-based-recommendations-help-more-states-tribes-and-territories
9. Hlouskova V, Hradkova P, Poustka J, et al. Occurrence of perfluoroalkyl substances (PFASs) in various food items of animal origin collected in four European countries. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2013;30(11):1918–1932. doi:10.1080/19440049.2013.837585
10. Guruge KS, Manage PM, Yamanaka N, Miyazaki S, Taniyasu S, Yamashita N. Species-specific concentrations of perfluoroalkyl contaminants in farm and pet animals in Japan. Chemosphere. 2008;73(suppl 1):S210–S215. doi:10.1016/j.chemosphere.2006.12.105
11. Frisbee SJ, Brooks AP, Maher A, et al. 2009. The C8 Health Project: Design, methods, and participants. Environ Health Perspect. 117(12):1873–1882. doi:10.1289/ehp.0800379
12. Kannan K, Perrotta E, Thomas NJ. Association between perfluorinated compounds and pathological conditions in southern sea otters. Environ Sci Technol. 2006;40(16):4943-8. doi:10.1021/es060932o
13. Soloff A C, Wolf BJ, White ND, et al. Environmental perfluorooctane sulfonate exposure drives T cell activation in bottlenose dolphins. J Appl Toxicol. 2017;37: 1108–1116. doi:10.1002/jat.3465
14. Coy CO, Steele AN, Abdulelah SA, et al. Differing behavioral changes in crayfish and bluegill under short- and long-chain PFAS exposures: Field study in Northern Michigan, USA. Ecotoxicol Environ Saf. 2022;247:114212. doi:10.1016/j.ecoenv.2022.114212
15. Wood C, Balazs GH, Rice M, et al. Sea turtles across the North Pacific are exposed to perfluoroalkyl substances. Environ Pollut. 2021 Jun 15;279:116875. doi:10.1016/j.envpol.2021.116875
16. Guillette TC, Jackson TW, Guillette M, McCord J, Belcher SM. Blood concentrations of per- and polyfluoroalkyl substances are associated with autoimmune-like effects in American alligators from Wilmington, North Carolina. Front Toxicol. 2022; 4:1010185. doi: 10.3389/ftox.2022.1010185 https://www.frontiersin.org/journals/toxicology/articles/10.3389/ftox.2022.1010185.
17. US Food Safey and Inspection Service. Chemical residues and contaminants. Accessed June 20, 2025. https://www.fsis.usda.gov/science-data/data-sets-visualizations/chemical-residues-and-contaminants