Hundreds of Unrecognized Halogenated Contaminants Discovered in Polar Bear Serum

Abstract

Exposure of polar bears (Ursus maritimus) to persistent organic pollutants was discovered in the 1970s, but recent evidence suggests the presence of unknown toxic chemicals in their blood. Protein and phospholipid depleted serum was stirred with polyethersulfone capillaries to extract a broad range of analytes, and nontarget mass spectrometry with “fragmentation flagging” was used for detection. Hundreds of analytes were discovered belonging to 13 classes, including novel polychlorinated biphenyl (PCB) metabolites and many fluorinated or chlorinated substances not previously detected. All analytes were detected in the oldest (mid-1980s) archived polar bear serum from Hudson Bay and Beaufort Sea, and all fluorinated classes showed increasing trends. A mouse experiment confirmed the novel PCB metabolites, suggesting that these could be widespread in mammals. Historical exposure and toxic risk has been underestimated, and emerging contaminants pose uncertain risks to this threatened species.

Fluorine Mass Balance and Suspect Screening in Marine Mammals from the Northern Hemisphere

“…Similarly, a homologue series of double bond or cyclic PFSAs (d/c PFSAs; class 9, C8-C10) were identified by first matching the parent mass and MS/MS spectrum for perfluoroethylcyclohexanesulfonate (PFECHS; C8; Figure S10) to those reported previously in polar bear serum. 40 Notably, PFECHS was prevalent in both ringed seals and harbor seals from Sweden relative to other samples, the former of which was found to have a significant quantity of missing EOF.…”

“…CL=3-4) was carried out by matching the exact mass of the precursor ions to those reported previously in polar bear serum. 40 For class 11, peaks for the C10 homologue eluted both at retention time 5.03 and 5.55 suggesting a mixture of structures (e.g. both an enol ethers and a cyclic ether).…”

“…46 Instrumental parameters are provided in the SI. The instrument was run in negative ion, full scan (200-1200 m/z) data dependent acquisition (DDA) MS/MS mode based on an inclusion list derived from a combination of online databases (abbreviated here as EPA, 47 KemI, 48 OECD, 49 and Trier 50 ), literature, 38,40,[51][52][53][54] and features identified from PFAS homologue series mining (details below)…”

“…Recent investigations in polar bear serum identified 35 additional PFASs that were not included in targeted analyses. 40 This included cyclic or unsaturated PFSAs, ether PFSAs, unsaturated ether-, cyclic ether-or carbonyl PFSAs, and x:2 chlorinated perfluoroalkyl ether sulfonates. The present study builds upon the work of Liu et al 40 by combining suspect screening with organofluorine mass balance to comprehensively assess PFAS exposure in eleven different marine mammal species from different locations within the Northern Hemisphere (Table S1).…”

“…40 This included cyclic or unsaturated PFSAs, ether PFSAs, unsaturated ether-, cyclic ether-or carbonyl PFSAs, and x:2 chlorinated perfluoroalkyl ether sulfonates. The present study builds upon the work of Liu et al 40 by combining suspect screening with organofluorine mass balance to comprehensively assess PFAS exposure in eleven different marine mammal species from different locations within the Northern Hemisphere (Table S1). To the best of our knowledge, this is the first time organofluorine mass balance combined with suspect screening has been conducted in marine mammals.…”