UV absorbents and industrial antioxidants in the food web of St. Lawrence Estuary beluga

Alexis Trinquet, Mathieu Babin, Alexis Agathi, Jonathan Verreault, Véronique Lesage, Jory Cabrol, Stéphane Lair, Gerald Tetreault, Zhe Lu

UV absorbents, including organic UV filters (UVFs) and benzotriazole UV stabilizers (BZT-UVs), are broadly used in the industry to prevent UV-light-induced skin issues or color changes of materials. These compounds can be found in sunscreens, personal care products, plastics, paints, and many other products. Industrial amine antioxidants are added to products such as plastics, rubbers, fuels, and lubricants to protect materials from oxidative degradation. These chemicals are of emerging environmental concern because they may cause adverse health effects in organisms. We previously detected some of these contaminants in the blubber and liver of St. Lawrence Estuary (SLE) beluga, a population that is considered endangered in Canada since 2014. Given that diet is a significant exposure pathway leading to the accumulation of contaminants in organisms, it is essential to understand how SLE beluga may uptake UV absorbents and industrial antioxidants from their food web. To fill this knowledge gap, we collected tissues from 17 known and potential prey of SLE beluga in 2019 and 2020. Our objectives were to investigate i) the concentrations and the biomagnification of UVFs, BZT-UVs, and industrial amine antioxidants in the SLE beluga's food web and; ii) identify the most probable dietary sources for these contaminants. Carbon sources and trophic levels of all beluga prey items were identified through stable isotope analyses and used to investigate relationships between prey ecology and contaminant concentrations. Our results clearly indicate that the levels of target contaminants followed the order of UVFs > BZT-UVs > industrial amine antioxidants. Among the 17 prey species, 14 were identified as potentially significant sources for these contaminants to the SLE beluga. UV328, a BZT-UV under evaluation by the Stockholm Convention on Persistent Organic Pollutants, was frequently detected in the beluga prey samples, and showed a positive correlation with δ15N values, indicating a biomagnification potential of UV328 in the SLE food web. This study is the first providing a baseline for monitoring these contaminants in the SLE food web and their fate in an estuarine environment.