Evidence for recent declines in PFASs and PBDEs in subsistence-harvested ice seals from Alaska

Ringed (Pusa hispida), bearded (Erignathus barbatus), spotted (Phoca largha), and ribbon (Histriophoca fasciata) seals are sea ice-associated seals and valuable subsistence resources for coastal Alaska Native communities. Per- and polyfluoroalkyl substances (PFASs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants that are prevalent in the Arctic, including Alaska's marine waters. We tested for 28 different PFASs in liver tissue from ringed (n = 10) and bearded (13) seals, and 51 different PBDE congeners or coelutions in blubber tissue from ringed (10), bearded (14), spotted (8), and ribbon (7) seals. Seals in this study were harvested during 2013-2016, ten years after previous studies of PFASs and PBDEs in Alaska's ice seals. Total concentrations of PFASs were three times lower in ringed and bearded seals from this study than in the past and lower than elsewhere in the Arctic. Only PBDE congeners BDE-47 and BDE-209 were found above minimum detection levels in 30-42% of ringed, spotted, and ribbon seals, and no PBDEs were above minimum detection levels in bearded seals. Most PFASs and PBDEs were not detected or present only in low concentrations. Although low levels of PFASs and PBDEs were detected in Alaska's ice seals, periodic monitoring should continue because novel, alternative fluorinated and brominated substances with the potential to bioaccumulate and biomagnify are being produced. Continued monitoring of ice seals for persistent organic pollutants, including PFASs and PBDEs, is critical for tracking these substances in the environment and assuring that seals remain safe for consumption.