Emission Changes Dwarf the Influence of Feeding Habits on Temporal Trends of Per- and Polyfluoroalkyl Substances in Two Arctic Top Predators

Abstract

We monitored concentrations of per- and polyfluoroalkyl substances (PFASs) in relation to climate-associated changes in feeding habits and food availability in polar bears (Ursus maritimus) and arctic foxes (Vulpes lagopus) (192 plasma and 113 liver samples, respectively) sampled from Svalbard, Norway, during 1997-2014. PFASs concentrations became greater with increasing dietary trophic level, as bears and foxes consumed more marine as opposed to terrestrial food, and as the availability of sea ice habitat increased. Long-chained perfluoroalkyl carboxylates (PFCAs) in arctic foxes decreased with availability of reindeer carcasses. The ∼9-14% yearly decline of C perfluoroalkyl sulfonates (PFSAs) following the cease in C PFSA precursor production in 2001 indicates that the peak exposure was mainly a result of atmospheric transport of the volatile precursors. However, the stable PFSA concentrations since 2009-2010 suggest that Svalbard biota is still exposed to ocean-transported PFSAs. Long-chain ocean-transported PFCAs increased 2-4% per year and the increase in C PFCAs in polar bears tended to level off since ∼2009. Emerging short-chain PFASs showed no temporal changes. Climate-related changes in feeding habits and food availability moderately affected PFAS trends. Our results indicate that PFAS concentrations in polar bears and arctic foxes are mainly affected by emissions.

Pelagic vs Coastal—Key Drivers of Pollutant Levels in Barents Sea Polar Bears with Contrasted Space-Use Strategies

“…For example, median concentrations of ∑CHLs were about 3.5 times higher in bears with a predominantly marine diet at the highest trophic level compared to the bears with a mixed diet at the lowest trophic level. Our results are in agreement with previous findings, which indicated that bears with a predominantly marine diet and higher trophic level accumulated higher concentrations of pollutants than bears at a lower trophic level, which fed on a mixed diet including terrestrial prey 20,24,44,70 .…”

“…Pollutants were ln-transformed to meet model assumptions. "Sampling year" was included in each model as a random factor to account for temporal variation of pollutant levels in Barents Sea polar bears70,71 . As suggested by Zuur et al72 , we used the restricted maximum likelihood estimation (REML) method to avoid any potential biased estimations.…”

Environmental contaminants modulate the transcriptional activity of polar bear (Ursus maritimus) and human peroxisome proliferator-activated receptor alpha (PPARA)

“…Furthermore, in vitro studies on Baikal seal and mouse indicate that PFASs act additively on PPARA at concentrations relevant for polar bears 15,71 . PFNA-mediated changes in PPARA functions are likely to increase in the future, as PFNA concentrations have increased 2.5% per year in Barents Sea polar bears during the period 2000–2014, whereas PFOS concentrations have been stable since 2009 72 . Furthermore, with the declining sea ice the Barents Sea, there is an increase in the use of offshore areas at the eastern Barents Sea by polar bears 73 , and bears using these areas have higher PFAS concentrations than those which stay close to the Svalbard Archipelago 74 .…”

Exposure to perfluoroalkyl substances and associations with serum thyroid hormones in a remote population of Alaska Natives

“…Unfortunately, PFTrDA was not measured in the current study. However, PFTrDA has been detected in numerous high trophic level arctic species at concentrations comparable to PFOA (Rotander et al, 2012; Routti et al, 2017). Future studies should assess exposure to long chain PFASs in the Arctic.…”