Organic ultraviolet (UV) lters have often been detected in aquatic ecosystems in concentrations ranging from ng/L to μg/L. However, both their acute and chronic effects on aquatic organisms have been insu ciently explored. This study aimed to rstly evaluate acute toxicity of some of the main UV lters used worldwide (2-ethylhexyl,4-methoxycinnamate/EHMC, avobenzone/AVO, benzophenone-3/BP-3, and octocrylene/OC), in three aquatic organisms (Artemia salina, Desmodesmus subspicatus, and Daphnia magna), to further investigate multigenerational effects in D. magna. After con rming the acute toxicity, D. magna individuals were chronically exposed to environmentally relevant concentrations of UV lters for two consecutive generations (F0 and F1), and reproductive endpoints, as well as catalase (CAT) and glutathione-S-transferase (GST) activities, were assessed. EHMC showed the most toxic potential, with the lowest EC 50 values for the three organisms. On the other hand, reproductive delays and a decrease in the reproduction rate were observed in the F1 generation exposed to AVO (4.4 µg/L), BP-3 (0.17 µg/L), EHMC (0.2 µg/L), and MIX. An increase of the CAT activity in organisms exposed to BP-3 and EHMC suggested induction of the antioxidant system. Although no reproductive effect was observed in the rst generation, toxic effects obtained in the F1 revealed the importance of multigenerational studies and the potential harm of UV lters to the life cycle of D. magna, even at environmentally relevant concentrations. This emphasizes the need for further studies considering these levels of exposure and more realistic experimental designs to better understand their potential risks.

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This research paper describes the study of a reduction-oxidation system using commercial steel wool (Fe) and HO for degradation of the dye Reactive Black 5 and aromatic compounds in water. The reductive process alone allowed the almost complete removal of color (97 ± 1 %) after 60 min of reaction. The decrease in spectral area (λ = 599 nm) associated with the chromophore group indicates breakage of the azo bonds. Moreover, the significant change in UV spectra can be associated with the formation of aromatic amines. Regarding the transformation products, a spectrophotometric method based on the diazotization reaction was employed to identify aromatic amines after reductive process, using sulfanilic acid as a model of aromatic amines. In addition, association with Fenton reagents improved the efficiency in the system with 93 ± 1 % degradation of intermediates formed during the reductive process. Ecotoxicological analysis revealed that the dye solution, after the reductive and oxidative processes, was not toxic to Lactuca sativa seeds. For Daphnia magna, the EC (%) values observed revealed that dye solution has an EC(%) = 74.1 and after reductive process, the toxicity increased (EC(%) = 63.5), which might be related to the formation of aromatic amines. However, after the Fenton process, the EC (%) was >100. These results demonstrated that the Fenton reaction using steel wool as an iron source was very efficient to decrease color, aromatic transformation products, and the ecotoxicity of Reactive Black 5 in solution.