Differences in PFAS exposure between Pacific pinnipeds: The Galapagos (Zalophus wollebaeki) and California (Zalophus californianus) sea lions

Per- and polyfluoroalkyl substances (PFAS) are a class of man-made persistent chemicals that have been detected in both terrestrial and aquatic environments and thus impact humans, household pets, agricultural species, and wildlife. PFAS exposure is linked to a variety of adverse health consequences, including cancer and immune disruption. This study investigates differences in PFAS exposure between California (CSL, n = 69) and Galapagos (GSL, n = 65) sea lion pups and juveniles across various sampling locations within each species' habitat range. Whereas the GSL were all considered healthy, 17 of the 69 CSL were classified as malnourished. Comparing the two species, significantly higher serum concentrations of summed PFAS, perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) were detected in CSL than in GSL. This elevated PFAS exposure in CSL is likely related to historic pollution in their environment and close proximity to the urbanized coastline of Southern California. Within species, malnourished CSL had significantly higher PFNA than healthy CSL pups. GSL pups also tended to have higher PFAS levels than GSL juveniles. Within the Galapagos archipelago, PFAS exposure differed between rookeries, with PFOS exceeding its method reporting limit (0.5 ng/mL) in every sample, including GSL from islands uninhabited by humans. Summed PFAS, PFNA, PFDA, and perfluoroundecanoic acid (PFUnA) were all significantly higher in sea lions sampled on uninhabited than inhabited islands in the Galapagos archipelago. This study is the first comprehensive report of PFAS in CSL and the first archipelago-wide assessment of PFAS in GSL.