Comparative review of the distribution and burden of contaminants in the body of polar bears

Abstract

Historical (or legacy) contaminants, such as metals and persistent organic pollutants (POPs; e.g., polychlorinated biphenyls) have been measured in circumpolar subpopulations of polar bears, especially from Hudson Bay, East Greenland and Svalbard, but substantially less is currently known about new and/or emerging contaminants such as polychlorinated naphthalenes, current-use pesticides, organotins, and polycyclic aromatic compounds. The polar bear is an apex Arctic predator that accumulates high levels of POPs and mercury, but there is currently no comprehensive profiling of the present knowledge on contaminants in tissue and body compartment in polar bears. Based on current literature reports and data, and including archived museum samples (as far back as the 1300s) and up to 2018, the aim of this review is to use available data to examine the comparative distribution and burden of mainly lipophilic contaminants in kidney, liver, fat, and other body compartments, such as milk, blood, and brain. Highlights from this review include the following: 1) the kidneys are one of the most important tissue depots of contaminants in polar bears; 2) there is a critical lack of data concerning the presence of metals of concern (other than mercury); and 3) there currently are no data available on the concentrations of many newer and emerging contaminants, which is especially relevant given the increasing oil and gas development in regions such as the Beaufort Sea (Canada). Additionally, given the vulnerability of polar bear populations worldwide, there is a need to develop non-invasive approaches to monitor contaminant exposure in polar bears.

Mercury abatement in the environment: Insights from industrial emissions and fates in the environment

“…For some apex predators, such as the polar bear, the kidney is a more critical organ for the deposition of Hg than the liver and muscles. The average Hg concentrations in polar bears' kidneys were 12.7 μg g −1 pre-2000 and 18 μg g −1 post-2000 [ 139 ], implying accumulation of Hg in the arctic habitats.…”

Persistent Organic Pollutants in Polar Ecosystems: Current Situation and Future Challenges Under Climate Change

“…According to more recent literature, there is a continual decrease in atmospheric POPs concentrations at the two poles [58]. In West Antarctica for example, from 2011 to 2017 the average concentration of eight PCBs (11,28,52,101,118,138, 153 and 180) went from 15.8 to 2.7 pg/m 3 , that of PBDEs from 1.2 to 0.5, HCHs from 9.6 to 1.11, DDTs from 4.7 to 0.7, endosulfane went from 6.73 to 0.5 and HCB varied from 222 to 149 pg/m 3 .…”

“…However, HCBs have been detected with very higher concentrations in Antarctic marine pelagic [98], also the temporal monitoring of PBDEs in Antarctic biota between 2000 and 2014 showed that the concentrations increased, unlike Arctic where there is a significant decrease [91]. It should also be noted that in Arctic, unlike many legacy pollutants, the concentrations of polychlorinated biphenyls (PCBs) and Chlordanes have remained relatively higher over the past decade in fauna [99][100][101]. Moreover, Higher concentrations of PCBs have been proven responsible for weakening the immune system of polar bears in Arctic [102,103].…”

Occurrence and Trophic Transfer of Polychlorinated Naphthalenes (PCNs) in the Arctic and Antarctic Benthic Marine Food Webs

“…Distant from intensive anthropogenic interference, the polar regions are considered ideal isolated ecosystems for screening global background levels of contaminants, as well as their congener composition, migration, and transformation mechanisms . Indeed, PCNs have existed in polar environments due to the global spread of atmospheric winds and ocean currents, , inclusive of air, snow, soil, and biota. − However, reports on the environmental behavior of PCNs in the Arctic and Antarctic regions are still limited, especially in terms of their bioaccumulation and biomagnification potential. While Kim et al explored the biomagnification of several PCN congeners in the Antarctic marine food web using trophic magnification factors (TMFs), no studies have holistically assessed the trophic transfer of all eight PCN homologues in the Arctic and Antarctic food webs.…”