PFAS accumulate in marine mammals<\/h2>\n
PFAS are a class of manufactured chemicals used in industrial and household products that are found in firefighting foams, food packaging, nonstick pans, fabrics, cosmetics and electronics. They\u2019re now produced and used all over the world.<\/p>\n
PFAS enter the sea mostly as wastewater and runoff. Species considered highly susceptible to contamination include sea otters and other predatory marine mammals with relatively long lifespans, in part because the chemicals can accumulate in high concentrations in animals that sit higher up on the food chain.<\/p>\n
Sea otters are mainly exposed by eating contaminated prey. Scientists also suspect that these chemicals may transfer to unborn otters by crossing the placenta or may pass to babies in mother\u2019s milk.<\/p>\n
The new study notes that \u201c[t]here is growing concern about the toxic effects of PFAS on marine life and the future negative impacts they will have on marine ecosystems as they continue to bioaccumulate and biomagnify in marine food webs.\u201d<\/p>\n
Canadian sea otters are not the only marine species affected by these chemicals. A 2022 study by several of the same researchers found PFAS in killer whales (Orcinus orca) in British Columbian waters. Older studies confirmed that sea otters in the U.S. states of California, Washington and Alaska, and across the Pacific in Russia, were contaminated with PFAS.<\/p>\n
Studying PFAS in sea otters<\/h2>\n
This was the first study looking at PFAS in British Columbia\u2019s sea otters, the northern subspecies (E. l. kenyoni), and finding research subjects was challenging. Samples can only ethically be taken from otters that have died, and they must be found, uneaten, shortly after death. The team was able to take liver tissue from 11 otters, as well as muscle samples from five of them. They tested these specimens for 40 types of PFAS.<\/p>\n
The lab analysis identified eight different PFAS chemicals in the animals\u2019 livers. Only one muscle sample tested positive, and just for a single type: perfluorooctanesulfonamide (PFOSA).<\/p>\n
That finding wasn\u2019t surprising. Because of the way PFAS bind to liver proteins, the chemicals readily accumulate in liver tissue. Researchers found that three types of forever chemicals comprised more than 80% of PFAS in the otters\u2019 livers: (PFOSA), perfluorononanoic acid (PFNA) and perfluorooctane sulfonate (PFOS), which is globally one of the most pervasive and widely studied types of PFAS.<\/p>\n
Concentrations were relatively low, according to Dana Price, the study\u2019s lead author, who is a master\u2019s degree student at UBC\u2019s Institute for the Oceans and Fisheries. Levels were far lower than those found in British Columbia\u2019s killer whales. One possible reason posited by the study authors was that sea otters have very fast metabolisms, which help them eliminate some contaminants: They eat roughly a quarter of their body weight in food every day.<\/p>\n The contaminant level was also significantly lower than that found in previous studies of sea otters in California \u2014 less than one-tenth the amount, likely because of higher levels of PFAS along that state\u2019s more developed, heavily populated coastline. Another factor may be the timing of the studies. The California research was conducted decades ago, and Price told Mongabay that pollution may be lower now in some regions because of new regulations for certain types of PFAS.<\/p>\n Under the Canadian Environmental Protection Act, PFOS and PFOSA were listed as toxic substances in 2006, reducing their manufacture and use; later, in 2012, certain other types of PFAS were added to that list.<\/p>\n The government is again taking action. In March 2025, the Canadian government\u2019s \u201cState of PFAS Report\u201d recommended that most PFAS be designated as \u201ctoxic substances\u201d and proposed tighter rules on its use, import and manufacture.<\/p>\n Parties to the Stockholm Convention on Persistent Organic Pollutants, an international environmental agreement, have also regulated PFOS and some PFAS. Unlike Canada, the U.S. is not a ratified party to the agreement. However, the U.S. Environmental Protection Agency negotiated with 3M, a leading PFAS manufacturer, to voluntarily phase out the use of PFOS, PFOSA and other related chemicals in the early 2000s.<\/p>\n Even at low levels, there can be negative health effects from exposure to PFAS. Yet it\u2019s hard to gauge the true consequences without further research, given that these chemicals don\u2019t exist in isolation, but interact with other contaminants, Price said.<\/p>\n Unlike whales, sea otters stay close to home. Since they usually have a range of no more than 50 square kilometers (19 square miles), they provide a better indicator of pollution in the area where they live.<\/p>\n The researchers categorized the 11 otters they tested into two groups: those living farther north, above Vancouver Island \u2014 an area relatively unpopulated by people \u2014 and a southern group found to the south or west, living near dense human populations and shipping lanes. Unsurprisingly, the northern group that lived in a more pristine location carried far lower PFAS concentrations than those living in more developed areas.<\/p>\n Both Price and Ross noted that it\u2019s unclear whether living sea otters contain similar levels of PFAS or if testing dead animals may have biased the results. They added that the study size was small, so more research is needed to confirm the findings.<\/p>\n Across the world, headlines regularly report PFAS pollution, and scientists, doctors, public health experts and conservationists have advocated regulating these chemicals.<\/p>\n Ross said he \u201cwholeheartedly\u201d supports the Canadian government\u2019s steps toward adopting tighter rules for PFAS. In his estimation, Canada tends to fall somewhere between the European Union, which has stricter rules for chemical contaminants such as PFAS, and the U.S., which takes more of a \u201cfree market\u201d approach.<\/p>\n Cassie Barker, senior program manager at Environmental Defence, a Toronto-based advocacy group, told Mongabay in an email that sea otters had made a \u201cjoyful recovery\u201d in British Columbia\u2019s waters but \u201cPFAS will continue to contaminate their homes, and potentially harm their health unless Canada bans these \u2018forever chemicals\u2019 from products.\u201d<\/p>\n \u201cWe urge Canada to follow through on its promise to protect species and people by declaring PFAS toxic and expediting necessary regulations to get these chemicals out of products,\u201d she said.<\/p>\n Price, D., Trites, A. W., Raverty, S., Cottrell, P., Cottrell, B., Zysk, I., & Alava, J. J. (2025). Concentrations of per- and polyfluoroalkyl substances in Canadian sea otters (Enhydra lutris) are higher near urban centers. Environmental Toxicology and Chemistry. doi:10.1093\/etojnl\/vgaf226<\/p>\n Lee, K., Alava, J. J., Cottrell, P., Cottrell, L., Grace, R., Zysk, I., & Raverty, S. (2022). Emerging contaminants and new POPs (PFAS and HBCDD) in endangered Southern Resident and Bigg\u2019s (Transient) killer whales (Orcinus orca): In utero maternal transfer and pollution management implications. Environmental Science & Technology, 57(1), 360-374. doi:10.1021\/acs.est.2c04126<\/p>\n Kannan, K., Agusa, T., Perrotta, E., Thomas, N. J., & Tanabe, S. (2006). Comparison of trace element concentrations in livers of diseased, emaciated and non-diseased southern sea otters from the California coast. Chemosphere, 65(11), 2160-2167. doi:10.1016\/j.chemosphere.2006.06.003<\/p>\n Hart, K., Gill, V. A., & Kannan, K. (2008). Temporal trends (1992\u20132007) of perfluorinated chemicals in northern sea otters (Enhydra lutris kenyoni) from south-central Alaska. Archives of Environmental Contamination and Toxicology, 56(3), 607-614. doi:10.1007\/s00244-008-9242-2<\/p>\n Andrews, D. Q., Stoiber, T., Temkin, A. M., & Naidenko, O. V. (2025). Discussion. Has the human population become a sentinel for the adverse effects of PFAS contamination on wildlife health and endangered species? Science of The Total Environment, 901. doi:<\/p>\nImpairing health<\/h2>\n
Potential regulation<\/h2>\n
Citations:<\/h2>\n