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Growth inhibition of UV filters on the freshwater microalga Scenedesmus acutus

Walton, Taylor
Belden, Jason B.
As the use of personal care products with organic ultraviolet (UV) filters are increasing, so is the exposure risk of these compounds to aquatic ecosystems. This study focuses on the inhibition growth effect of four common UV filters on the freshwater microalgae, Scenedesmus acutus. Fluorescence of chlorophyll a was used as a measure of growth during a 96-h exposure period, and growth inhibition was utilized as the endpoint. All UV filters inhibited growth with increasing concentration, except for avobenzone and octisalate, which did not decrease reproduction at any treatment level up to water solubility. Lowest observed effect concentrations for atrazine, homosalate, and oxybenzone were 117 μg/L, 100 μg/L, and 1875 μg/L, respectively. Homosalate was the most toxic UV filter followed by oxybenzone with avobenzone and octisalate likely to be not toxic to S. acutus. These results indicate that toxicity to freshwater algae is not likely at environmentally relevant concentrations. However, further research should consider the impact of UV light on toxicity.