Synergistic effects of two commonly used personal care products, benzophenone-3 (BP-3) and N,N-diethyl-meta-toluamide (DEET), on amphibian survival and development

Abstract

The UV filter benzophenone 3 (BP-3) and the insect repellent N,N-diethyl-meta-toluamide (DEET) are considered emerging contaminants due to the growing concern about their release in aquatic environments and possible risks. The single and mixture toxicity of BP-3 and DEET in embryos and larvae of Rhinella arenarum was assessed. Lethality bioassays were conducted, and biomarkers (catalase, glutathione S-transferase, reduced glutathione, lipid peroxidation, acetylcholinesterase, and butyrylcholinesterase) were analyzed at environmentally relevant concentrations (1 and 5 µg/L). Toxicity was time and stage-dependent, with embryos more sensitive than larvae. BP-3 was more toxic, (504h-LC50: 0.076 mg/L for embryos, 1.22 mg/L for larvae) than DEET (504h-LC50: 24.35 mg/L for embryos, 55.23 mg/L for larvae). Mixture exposure produced synergistic effects. Oxidative stress and cholinergic alterations were observed for both compounds. The 1 µg/L mixture potentiated GST and AChE responses. These results emphasize the need to monitor these contaminants and evaluate their ecological risks.