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Environ Sci Technol. 2017 Oct 3;51(19):11431-11439. doi: 10.1021/acs.est.7b03532. Epub 2017 Sep 25.

Effects of Polar Bear and Killer Whale Derived Contaminant Cocktails on Marine Mammal Immunity.

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Department of Bioscience, Arctic Research Centre, Aarhus University , Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark.
Department of Pathobiology and Veterinary Science, University of Connecticut , 61 North Eagleville Road, Storrs, Connecticut 06269-3089, United States of America.
Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University , Ottawa, Ontario Canada K1A 0H3.
Department of Arctic and Marine Biology, University of Tromsø - the Arctic University of Norway , Breivika, 9037 Tromsø, Norway.
Aalborg Zoo/Aalborg University , Mølleparkvej 63, DK-9000 Aalborg, Denmark.
Copenhagen ZOO, Roskildevej 38, PO Box 7, DK-2000 Frederiksberg, Denmark.
SeaWorld Parks and Entertainment, 500 SeaWorld Drive, San Diego, California 92109, United States of America.
Loro Parque Fundación, Avda. Loro Parque, s/n 38400 Puerto de la Cruz, Tenerife Spain.


Most controlled toxicity studies use single chemical exposures that do not represent the real world situation of complex mixtures of known and unknown natural and anthropogenic substances. In the present study, complex contaminant cocktails derived from the blubber of polar bears (PB; Ursus maritimus) and killer whales (KW; Orcinus orca) were used for in vitro concentration-response experiments with PB, cetacean and seal spp. immune cells to evaluate the effect of realistic contaminant mixtures on various immune functions. Cytotoxic effects of the PB cocktail occurred at lower concentrations than the KW cocktail (1 vs 16 μg/mL), likely due to differences in contaminant profiles in the mixtures derived from the adipose of each species. Similarly, significant reduction of lymphocyte proliferation occurred at much lower exposures in the PB cocktail (EC50: 0.94 vs 6.06 μg/mL; P < 0.01), whereas the KW cocktail caused a much faster decline in proliferation (slope: 2.9 vs 1.7; P = 0.04). Only the KW cocktail modulated natural killer (NK) cell activity and neutrophil and monocyte phagocytosis in a concentration- and species-dependent manner. No clear sensitivity differences emerged when comparing cetaceans, seals and PB. Our results showing lower effect levels for complex mixtures relative to single compounds suggest that previous risk assessments underestimate the effects of real world contaminant exposure on immunity. Our results using blubber-derived contaminant cocktails add realism to in vitro exposure experiments and confirm the immunotoxic risk marine mammals face from exposure to complex mixtures of environmental contaminants.

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