Ecotoxicidade de misturas dos filtros solares avobenzona, octocrileno e oxibenzona em plantas

Abstract

This study aimed to assess the toxicity of emerging pollutants from the sunscreen class avobenzone (AVB), octocrylene (OCT), and oxybenzone (OXB), alone and in mixtures, on the plants Cucumis sativus, Daucus carota, Solanum lycopersicum, and Allium cepa, using multiple biomarkers. The tests were conducted between March and October 2024 at Federal University of Technology – Paraná (UTFPR) in Campo Mourão. The concentrations tested were AVB 1 and 10 ng/L, OCT 10 and 100 μg/L, and OXB 2 and 20 μg/L, and the mixtures were prepared by binary associations AVB-OCT, AVB-OXB, and OCT-OXB. Seeds of C. sativus, D. carota, and S. lycopersicum were germinated for phytotoxicity evaluation using the Germination Index (GI) and Relative Growth Index (RGI). A. cepa bulbs were used to assess cytotoxicity using the Mitotic Index (MI) and genotoxicity using the Index of Cellular Alterations (ICA). Roots of all species were used to assess oxidative stress via enzymatic activity of the enzymes catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPOX), and superoxide dismutase (SOD). The roots of A. cepa bulbs were used to assess oxidative stress via non-enzymatic means through antioxidant activity (DPPH), phenolic content (FC), and lipid peroxidation (TBARS). The bulbs were also used to obtain the absorption rate of the filters by the plant. As a result, the filters were phytotoxic by reducing root elongation in specific cases when isolated and predominantly in the mixtures at both concentrations. It was observed that lower concentrations can cause greater effects on seeds compared to higher concentrations because they are more absorbed by the roots. All treatments were cytotoxic by reducing cell division and genotoxic by inducing altered chromosomal disorders and losses, with more pronounced effects in mixtures and peak ICA for AVB-OCT. All the treatments caused oxidative stress with modulations of CAT, APX, GPOX, and SOD, with AVB, OXB, AVB-OCT, and AVB-OXB standing out, which indicated an excess of reactive oxygen species (ROS) of the hydrogen peroxide (H2O2) type, damage to the cell membrane and wall, and the occurrence of superoxide (O2-) related to the chromosomal alterations observed. It was also possible to establish a relationship between the filters that caused the most damage to the enzymes and the filters most absorbed by the roots. The treatments also caused oxidative stress via non-enzymatic pathways with DPPH inhibition, production of FC for AVB, AVB-OXB and OCT-OXB, and induction of TBARS for AVB and AVB-OXB. In general, the AVB-OCT mixture showed the greatest potential for synergy and increased damage and AVB played a key role by being present in the most toxic treatments, alone or in a mixture. The scenario found is dangerous for agriculture and organisms due to the high probability of exposure to the mixtures. It is suggested to search for alternative sources of solar protection, investment in advanced treatment technologies for WWTPs and legislative updates. The research provided unprecedented insights into the behavior of pollutants in complex mixtures and their different mechanisms of action on plants.