Assessment of aryl hydrocarbon receptor mediated toxicity of benzotriazole ultraviolet stabilizers (UV-P, UV-9, UV-090) to fishes

Benzotriazole ultraviolet stabilizers (BUVSs) are a class of chemical contaminants used to help counter UV-induced damage to manufactured goods, especially plastics. The broad applicability of BUVSs has resulted in their ubiquitous detection in aquatic ecosystems and biota. Although BUVSs are detected globally in aquatic ecosystems, a limited number of studies have investigated the potential toxic effects of BUVSs to fish. Of the limited toxicity data for BUVSs, studies suggest that certain BUVSs might dysregulate the aryl hydrocarbon receptor (AhR) causing early life-stage toxicity in fishes. Therefore, the objectives of this study were to use in vivo and in vitro approaches to characterize the toxicity of 2-(benzotriazol-2-yl)-4-methylphenol (UV-P), 2-(Benzotriazol-2-yl)-4-methyl-6-prop-2-enyl-phenol (UV-9), and 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate (UV-090) as agonists of the AhR across a phylogenetically diverse number of fish species. In vivo toxicity was assessed by exposing zebrafish (Danio rerio) to BUVSs by microinjection and toxicities were assessed by recording embryo mortality and malformations including yolk sac and pericardial edema, and spinal curvature. Each of the tested BUVSs caused dose-dependent increases in embryo mortality following exposure. In vitro activation of the AhR by BUVSs was determined with a luciferase reporter gene (LRG) assay using COS-7 cells transfected with the AhR of zebrafish or eight other species. Results confirm that UV-P and UV-9, cause toxicity via AhR activation whereas, UV-090 lacked the ability to activate the AhR, indicating that its toxicity is independent of the AhR. Furthermore, interspecies differences in sensitivity to AhR activation by BUVSs was observed. Overall, this study fills knowledge gaps regarding the potential toxic effects of BUVSs to fishes and can help guide improved objective assessment of risks posed by BUVS that have AhR agonistic properties for the protection of Canada’s