Review of Environmental Occurrence and Toxicity of Benzotriazole Ultraviolet Stabilizers.

Benzotriazole ultraviolet stabilizers (BUVs), extensively used synthetic UV absorbers, are established global contaminants exhibiting persistence and bioaccumulation. Ubiquitously detected in diverse environmental matrices (water, wastewater, sediment, air, dust, and soil) and organisms, their distribution shows significant regional and seasonal variations driven by urbanization and wastewater discharge. Notably, UV-328, UV-329, UV-234, and UV-P occur at elevated concentrations, with air and dust being the most contaminated media (even reaching levels ng/g to μg/g dw). Toxicological studies demonstrate that BUVs induce multifaceted biotoxicity, including endocrine toxicity, reproductive and developmental toxicity, immunotoxicity, hepatotoxicity, and neurotoxicity. Endocrine toxicity is the most extensively characterized effect. Moreover, BUVs disrupt critical human physiological processes and impair plant photosynthesis. Biotoxicity is mediated through molecular mechanisms: AHR pathway, ER/ERR activation, oxidative stress, lipid metabolism, and apoptosis. Among the BUVs, toxic mechanisms of UV-P, UV-234, UV-329, and UV-326 have been studied comprehensively. Notably, UV-P shows the highest estrogenic activity. While current environmental risks are assessed as low to moderate, future ecological disturbances are plausible due to intensifying anthropogenic pressures or bioaccumulation. Despite growing evidence, knowledge gaps persist regarding environmental fate and toxicology mechanisms. This review synthesizes BUVs contamination profiles, ecotoxicological impacts, and risk assessments, informing strategies to mitigate BUVs persistence and toxicity.