Unexpectedly high concentrations of forever chemicals found in dead sea otters

A new paper in Environmental Toxicology and Chemistry, published by Oxford University Press, finds high qualities of toxic “forever” chemicals in sea otters recovered off the Pacific Ocean.

Per- and polyfluoroalkyl substances, so called “Forever Chemicals,” are used in the lining of food packaging, non-stick cookware, waterproof and stainproof textiles, cosmetics, firefighting foams, and electronics. These chemicals, which bioactively bind to proteins within an organism, can cause immunotoxicity, organ damage, endocrine disruption, and reproductive impairments in wildlife. Some chemicals have been phased out from use in many countries. However, they endure in the environment.

Forever chemicals travel through water, soil, and the atmosphere—and are found in all parts of the world including the polar regions far from human industrial activity. There is growing concern about the toxic effects of these chemicals on marine life, and the future negative impacts they will have on marine ecosystems as they continue to accumulate in marine food webs. Species considered highly susceptible to contamination include predatory marine mammals with relatively long lifespans such as sea otters and killer whales. Sea otters are exposed to such chemicals mainly via consumption of prey that contain forever chemicals, through maternal transfer and lactation may also play a role.

Sea otters consume large amounts (approximately 25% of their body weight each day) of protein-rich seafood in nearshore habitats that are susceptible to chemical exposure and bioaccumulation. Sea otters do not migrate or travel great distances and are therefore useful indicators for region-specific analysis of contaminant accumulation from food sources often harvested and consumed by humans. In British Columbia, sea otters were entirely killed off by the fur trade that occurred from mid-1700s to the early 1900s—and only returned to the province after scientist relocated 89 animals from Alaska between 1969 and 1972. Since then, their population has grown to over 8,000 animals as of 2017. Investigators have found that higher concentrations of forever chemicals are correlated with a greater probability of (California) sea otters dying from infectious and non-infectious diseases, indicating a significant health risk to the species.

Researchers here analyzed liver and skeletal muscle samples from dead sea otters recovered from coastal British Columbia. The investigators collected a total of 16 samples from the livers and skeletal muscles of 11 animals.

They found eight of the 40 tested chemicals were present in all sampled sea otters, although concentrations of each varied between individuals. Sea otter livers contained more of them chemical compounds at higher total average concentrations than skeletal muscles. Only perfluorooctanesulfonamide, a compound was used to repel grease and water in food packaging and once a part of 3M’s Scotchgard formula, was identified in both liver and muscle tissues, while the scientists here found the remaining seven chemicals only in the animals’ livers. The researchers found that chemical concentrations were over three times higher on average in sea otters found near major cities and shipping routes.

The paper, “Concentrations of Per- and Polyfluoroalkyl Substances in Canadian Sea Otters (Enhydra lutris) are Higher Near Urban Centers,” is available (at midnight on November 4th) at https://doi.org/10.1093/etojnl/vgaf226.

Direct correspondence to: 
Dana Price
Marine Mammal Research Unit
University of British Columbia
d.price@oceans.ubc.ca

To request a copy of the study, please contact:
Daniel Luzer 
daniel.luzer@oup.com