Acute toxicity assessment of nine organic UV filters using a set of biotests

UV filters in environmental compartments are a source of concern related to their ecotoxicological effects. However, little is known about UV filters' toxicity, particularly those released into the environment as mixtures. Acute toxicity of nine organic UV filters benzophenone-1, benzophenone-2, benzophenone-3, 4-methoxy benzylidene camphor, octocrylene, ethylhexyl methoxycinnamate, 2-ethylhexyl salicylate, homosalate, and butyl methoxydibenzoylmethane was determined. UV filter solutions were tested as single, binary, and ternary mixtures of various compositions. Single solutions were tested using a set of bio tests, including tests on saline crustaceans (Artemia franciscana), freshwater crustaceans (Daphnia magna), marine bacteria (Aliivibrio fischeri), and freshwater plants (Lemna minor). The tests represent different stages of the trophic chain, and hence their overall results could be used to risk assessment concerning various water reservoirs. The toxicity of binary and ternary mixtures was analyzed using the standardized Microtox^® method. Generally, organic UV filters were classified as acutely toxic. Octocrylene was the most toxic for Arthemia franciscana (LC₅₀ = 0.55 mg L^-1) and Daphnia magna (EC₅₀ = 2.66-3.67 mg L^-1). The most toxic against freshwater plants were homosalate (IC₅₀ = 1.46 mg L^-1) and octocrylene (IC₅₀ = 1.95 mg L^-1). Ethylhexyl methoxycinnamate (EC₅₀ = 1.38-2.16 mg L^-1) was the most toxic for marine bacteria. The least toxic for crustaceans and plants were benzophenone-1 (EC₅₀ = 6.15-46.78 mg L^-1) and benzophenone-2 (EC₅₀ = 14.15-54.30 mg L^-1), while 4-methoxy benzylidene camphor was the least toxic for marine bacteria (EC₅₀ = 12.97-15.44 mg L^-1). Individual species differ in their sensitivity to the tested organic UV filters. An assessment of the toxicity of mixtures indicates high and acute toxicity to marine bacteria after exposition to a binary mixture of benzophenone-2 with octocrylene, 2-ethylhexyl salicylate, or homosalate. The toxicity of mixtures was lower than single solutions predicting antagonistic interaction between chemicals.