John Wiley & Sons, Ltd.

Enzyme induction and histopathology elucidate AhR vs. non‐AhR mediated effects of aroclor 1268 in American mink (Neovison vison)

Polychlorinated biphenyl (PCB) concentrations reported in preferred prey and blubber of bottlenose dolphins from the Turtle‐Brunswick River Estuary (TBRE, Georgia, USA) suggests the potential for adverse effects. However, PCBs in TBRE dolphins are primarily derived from Aroclor 1268, and predicting toxic effects of Aroclor 1268 is uncertain due to the mixture's unique composition and associated physiochemical characteristics. These differences suggest toxicity benchmarks for other PCB mixtures may not be relevant to dolphins exposed to Aroclor 1268. American mink (Neovison vison) were used as a surrogate model for cetaceans to characterize mechanisms of action associated with Aroclor 1268 exposure. Mink share similarities in phylogeny and life history with cetaceans and are characteristically sensitive to PCBs, making them an attractive surrogate species for marine mammals in ecotoxicity studies. Adult female mink and a subsequent F1 generation were exposed to Aroclor 1268 through diet, and effects on enzyme induction, histopathology, thyroid hormone regulation, hematology, organ weights, and body condition index were compared to a negative control and a 3,3',4,4',5‐pentachlorobiphenyl (PCB 126) positive control. Aroclor 1268 dietary exposure concentrations ranged from 1.8 to 29 µg/g ww. Anemia, hypothyroidism, and hepatomegaly were observed in mink exposed to Aroclor 1268 beyond various dietary thresholds. Cytochrome P450 induction and squamous epithelial proliferation (SEP) jaw lesions were low in Aroclor 1268 treatments relative to the positive control. Differences in enzyme induction and the development of SEP jaw lesions between Aroclor 1268 treatments and the positive control, coupled with effects observed in Aroclor 1268 treatments not observed in the positive control, indicate that mechanisms additional to the aryl hydrocarbon receptor (AhR)‐mediated pathway are associated with Aroclor 1268 exposure. This article is protected by copyright. All rights reserved

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