Embryonic Exposure to Benzotriazole UV Stabilizer 327 (UV-327) Alters Behaviour of Rainbow Trout Alevin.

Benzotriazole ultraviolet stabilizers (BUVSs) are used in great quantities during industrial production of a variety of consumer and industrial goods. Due to leaching and spill, BUVSs are detectable ubiquitously in the environment. As of May 2023, citing concerns related to bioaccumulation, biomagnification, and environmental persistence, (B)UV(S)-328 was recommended to be listed under Annex A of the Stockholm Convention on Persistent Organic Pollutants. However, a phase out of UV-328 could result in a regrettable substitution, as the replacement chemical(s) could cause similar or unpredicted toxicity in vivo, relative to the UV-328. Therefore, the influence of UV-327, a potential replacement of UV-328, was investigated with respected to early life development of newly fertilized rainbow trout embryos (Oncorhynchus mykiss), microinjected with environmentally relevant concentrations of UV-327. Developmental parameters (standard length), energy consumption (yolk area), heart function, blue sac disease, mortality, and behaviour were investigated. Alevins at 14 days post-hatching, exposed to 107 ng UV-327 g-1 egg, presented significant signs of hyperactivity, as they moved on average 1.8-fold the distance and at 1.5-fold the velocity of controls. Although a substantial reduction in body burden of UV-327 was observed at hatching, it is postulated that UV-327, due to its lipophilic properties, interfered with neurological development and signaling from the onset of neurogenesis. If these results hold true across multiple taxa and species, a potential contributor to neurodevelopmental disorders might have been identified. These findings suggest that UV-327 pose an unknown hazard to rainbow trout embryos and alevins, rendering UV-327 a potential regrettable substitution to UV-328. However, a qualified statement on a regrettable substitution requires a comparative investigation on the teratogenic effects between the two BUVSs.