Cellular and Systemic Toxicity Induced by Sunscreen and Paraben Mixtures and the Implications for Root Development in...

Sunscreens and parabens contaminate agricultural areas worldwide; however, the effects of these micropollutants in mixture on cultivated plants have not yet been reported. This study evaluated the cellular and systemic toxicity induced by octocrylene (OC), methylparaben (MeP), and butylparaben (BuP), individually at concentrations of 10, 50, 100, and 500 ng·L^-1, as well as by equimolar binary mixtures (1:1) of OC with MeP and OC with BuP, in seeds of Cucumis sativus L. and Lycopersicum esculentum L., and in roots of Allium cepa L. bulbs. The OC + MeP mixtures induced H₂O₂ accumulation, whereas the OC + BuP mixtures promoted lipid peroxidation in the root meristems of A. cepa, resulting in significant mitodepressive, aneugenic, and clastogenic effects. The OC + BuP combination markedly reduced root growth in the three evaluated species and, in onion, caused mitotic indices below 50% compared to the control, demonstrating severe cytotoxicity to the meristems. In contrast, the OC + MeP combination stimulated root growth in cucumber, tomato, and onion. However, although significantly longer, the formed roots exhibited greater susceptibility to breakage than the control, indicating that growth predominantly associated with cell elongation, without concomitant cell proliferation. The interaction between the compounds was characterized as synergistic for OC + MeP and additive for OC + BuP, with BuP being the main determinant of mixture toxicity. Thus, mixtures of OC + MeP and OC + BuP may impair the early establishment of crops by affecting root system functionality, delaying or inhibiting root development, and altering root structural stability. These effects indicate that the presence of these micropollutant mixtures in contaminated agricultural soils may negatively influence plant development and the agronomic performance of cultivated plants.