Bioaccumulation and biomagnification of perfluoroalkyl acids and precursors in East Greenland polar bears and their ringed seal prey
By Gabriel Boisvert, Christian Sonne, Frank F. Rigét, Rune Dietz, and Robert J. Letcher
June 11, 2019
The bioaccumulation and biomagnification of 22 major perfluoroalkyl substances (PFAS) were investigated in tissues of polar bears (Ursus maritimus) and their major prey species, the ringed seal (Pusa hispida), from the Scoresby Sound region of East Greenland. In polar bear liver the mean ΣPFSA (perfluoroalkyl sulfonic acid) concentration (C, C, C and C) was 2611 ± 202 ng/g wet weight (ww; 99% perfluorooctane sulfonate (PFOS)) and two orders of magnitude higher than the 20 ± 3 ng/g ww (89% PFOS) concentration in fat. The mean ΣPFSAs in seal liver was 111 ± 5 ng/g ww (98% PFOS) and three orders of magnitude higher relative to the 0.05 ± 0.01 ng/g ww concentration in blubber (100% perfluorohexane sulfonate). Perfluoro-1-octane sulfonamide (FOSA) was quantifiable in bear (mean 10 ± 1.4 ng/g ww) and seal (mean 0.6 ± 0.1 ng/g ww) liver but not in fat or blubber. The mean ΣPFCAs (C-C; perfluoroalkyl carboxylic acids) in bear liver (924 ± 71 ng/g ww) was much greater than in seal liver (74 ± 6 ng/g ww). In bear fat and seal blubber, the mean ΣPFCAs were 15 ± 1.9 and 0.9 ± 0.1 ng/g ww, respectively. Longer chain C to C PFCAs dominated in bear fat and seal blubber (60-80% of ΣPFCA), whereas shorter-chain C to C PFCAs dominated in the liver (85-90% of ΣPFCA). Biomagnification factors (BMFs) were orders of magnitude greater for PFHxS and C to C PFCAs when based on bear liver to seal blubber rather than bear liver to seal liver, and PFCA (C to C) BMFs decreased with increasing chain length. Seal blubber to bear liver BMFs better reflects the dietary exposure relationship of PFAS between bears and seals.