Biomarkers activity in Oreochromis niloticus under sub-chronic exposure to a UV filters ternary mixture

The behavior of organic UV filters in aquatic ecosystems and living organisms raises concern. For the first time, biochemical biomarkers were evaluated in the liver and brain of juvenile Oreochromis niloticus exposed to 0.001 and 0.5 mg L-1 of a benzophenone-3 (BP-3), octyl methoxycinnamate (EHMC), and octocrylene (OC) mixture for 29 days. Before the exposure, the stability of these UV filters was investigated using liquid chromatography. The experiment with aeration in the aquarium showed a high percentage of concentration reduction (%) after 24 h: 62 +/- 2 for BP-3, 96 +/- 6 for EHMC, and 88 +/- 2 for OC versus 5 +/- 4 for BP-3, 8 +/- 7 for EHMC, and 2 +/- 3 for OC when without aeration. These results defined the bioassay protocol. The stability of the filters concentrations after being stored in PET flasks and subjected to freezing and thawing cycles was also verified. In PET bottles, the BP-3, EHMC, and OC presented concentration reductions of 8 +/- 1, 28 +/- 7 and 25 +/- 5 respectively, after 96 h storage and four freezing cycles. In falcon tubes the concentration reductions observed were 47 +/- 2 for BP-3, >95 +/- 1 for EHMC and 86 +/- 2 for OC after 48 h and two cycles. The 29 days of sub-chronic exposure indi-cated the occurrence of oxidative stress through the enhanced lipid peroxidation (LPO) levels for the groups exposed to both bioassay concentrations. The catalase (CAT), glutathione-S-transferase (GST), and acetylcho-linesterase (AChE) activities did not show significant alterations. The genetic adverse effects were analyzed in erythrocytes of fish exposed to 0.001 mg L-1 of the mixture by comet and micronucleus biomarkers and no significant damage was observed.

Automated summary

This study evaluated the impact of the mixture of benzophenone-3 (BP-3), octyl methoxycinnamate (EHMC), and octocrylene (OC) on the biochemical biomarkers in the liver and brain of juvenile Oreochromis niloticus. The sub-chronic exposure for 29 days led to oxidative stress, while no significant genetic damage was observed.