Physiologically-based pharmacokinetic modelling of immune, reproductive and carcinogenic effects from contaminant exposure in polar bears ( Ursus maritimus ) across the Arctic

• Published in: Environmental Research
• Main Authors: Dietz, Rune, Gustavson, Kim, Sonne, Christian, Desforges, Jean-Pierre, Rigét, Frank F., Pavlova, Viola, McKinney, Melissa A., Letcher, Robert J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: polar bear; organohalogen contaminants; PBPK modelling; critical body residue; immune suppression; reproductive toxicity; risk quotient; Arctic; Greenland; Svalbard; East Greenland; Ursus maritimus; Alaska
• Online Access: https://pure.au.dk/portal/da/publications/physiologicallybased-pharmacokinetic-modelling-of-immune-reproductive-and-carcinogenic-effects-from-contaminant-exposure-in-polar-bears-ursus-maritimus-across-the-arctic(c934a3f5-57b3-4995-8f25-d2f65818e2ea).html; https://doi.org/10.1016/j.envres.2015.03.011

Polar bears (Ursus maritimus) consume large quantities of seal blubber and other high trophic marine mammals and consequently have some of the highest tissue concentrations of organohalogen contaminants (OHCs) among Arctic biota. In the present paper we carried out a risk quotient (RQ) evaluation on OHC-exposed polar bears harvested from 1999 to 2008 and from 11 circumpolar subpopulations spanning from Alaska to Svalbard in order to evaluate the risk of OHC-mediated reproductive effects (embryotoxicity, teratogenicity), immunotoxicity and carcinogenicity (genotoxicity). This RQ evaluation was based on the Critical Body Residue (CBR) concept and a Physiologically-Based Pharmacokinetic Modelling (PBPK) approach using OHC concentrations measured in polar bear adipose or liver tissue. The range of OHC concentrations within polar bear populations were as follows for adipose, sum polychlorinated biphenyls ∑PCBs (1797-10,537ng/g lw), sum methylsulphone-PCB ∑MeSO2-PCBs (110-672ng/g lw), sum chlordanes ∑CHLs (765-3477ng/g lw), α-hexachlorocyclohexane α-HCH (8.5-91.3ng/g lw), β-hexachlorocyclohexane β-HCH (65.5-542ng/g lw), sum chlorbenzenes ∑ClBzs (145-304ng/g lw), dichlorodiphenyltrichloroethane ∑DDTs (31.5-206ng/g lw), dieldrin (69-249ng/g lw), polybrominated diphenyl ethers ∑PBDEs (4.6-78.4ng/g lw). For liver, the perfluorooctanesulfonic acid (PFOS) concentrations ranged from 231-2792ng/g ww. The total additive RQ from all OHCs ranged from 4.3 in Alaska to 28.6 in East Greenland bears for effects on reproduction, immune health and carcinogenicity, highlighting the important result that the toxic effect threshold (i.e. RQ>1) was exceeded for all polar bear populations assessed. PCBs were the main contributors for all three effect categories, contributing from 70.6% to 94.3% of the total risk and a RQ between 3.8-22.5. ∑MeSO2-PCBs were the second highest effect contributor for reproductive and immunological effects (0.17<RQ<1.4), whereas PFOS was the second highest effect contributor for carcinogenic ...