Perfluoroalkyl Substances in Seabird Eggs from Canada's Pacific Coast: Temporal Trends (1973-2019) and Interspecific Patterns

Much less is known about temporal trendsof PFASs in toppredators that range across the North Pacific Ocean. This study reportsdecreasing trends in PFAS concentrations in the eggs of 4 seabirdspecies sampled along a nearshore-offshore gradient. Whether perfluoroalkyl sulfonates (PFSAs) and perfluoroalkylcarboxylates(PFCAs) are responding to legislative restrictions and showing decreasingtrends in top marine predators that range across the eastern NorthPacific Ocean is unclear. Here, we examined longer-term temporal trends(1973-2019) of 4 PFSAs and 13 PFCAs, as well stable isotopesof & delta;C-13 and & delta;N-15, in the eggs of4 seabird species sampled along a nearshore-offshore gradient; double-crestedcormorants (Nannopterum auritum), pelagiccormorants (Urile pelagicus), rhinocerosauklets (Cerorhinca monocerata), andLeach's storm-petrels (Hydrobates leucorhous) from the Pacific coast of British Columbia, Canada. PFOS was themost abundant PFSA (79-94%) detected in all eggs regardlessof colony and year, with the highest concentrations, on average, measuredin auklet eggs (mean = 58 ng g(-1), range = 11-286ng g(-1) ww). Perfluoroundecanoic acid (PFUdA) andperfluorotridecanoic acid (PFTriDA) were the dominant long-chain PFCAs(& GE;30% combined). The majority of PFSAs (including PFOS) arestatistically declining (p < 0.001) in the eggsof all 4 species with PFOS half-lives ranging from 2.6 to 7.8 years.Concentrations of long-chain PFCAs exhibited a trajectory comprisedof linear increases and second-order declines, suggesting that therate of uptake of PFCAs is slowing or leveling off. These trends areconsistent with the voluntarily ceased production of PFSAs by 3M circa2000-2003 and are among the first from the northeast Pacificto indicate a positive response to several regulations and restrictionson PFCAs from facility emissions and product content.

Automated summary

This study reports decreasing trends in PFAS concentrations in the eggs of 4 seabird species sampled along a nearshore-offshore gradient. The majority of PFSAs, including PFOS, are statistically declining in the eggs of all 4 species, while concentrations of long-chain PFCAs exhibit a trajectory of linear increases and second-order declines.