Ecotoxicidade do metilparabeno e octocrileno em mistura sobre plantas terrestres

Abstract

Emerging pollutants, such as pharmaceuticals, parabens, and sunscreens, are being increasingly detected in aquatic and terrestrial environments, raising concerns about the risk of adverse effects on non-target organisms. Despite the topic's relevance, knowledge gaps still exist regarding their impacts, especially under combined exposure conditions. Therefore, this study aimed to evaluate the individual and mixture toxicity of Methylparaben (MPB) and Octocrylene (OCT) in plant species, using germination and root elongation assays in Cucumis sativus L. and Solanum lycopersicum L., as well as cytogenetic and biochemical analyses in roots of Allium cepa L. Seeds and bulbs were exposed to different concentrations of the compounds (10, 50, 100, and 500 μg/L). Regarding the results, although the individual compounds did not show evident phytotoxicity in germination assays, the main finding was observed in A. cepa: the mixture of OCT and MPB induced severe cytotoxicity, manifested by a drastic reduction in cell division (mitotic index), and high genotoxicity, indicated by a significant increase in the number of chromosomal alterations. Curiously, this cellular damage occurred paradoxically with an increase in root elongation, rather than an inhibition, evidencing that cellular damage preceded the macroscopic effect. Biochemical analyses confirmed that the toxicity mechanism behind this damage was oxidative stress, with elevated lipid peroxidation and pronounced activation of antioxidant enzymes, especially upon exposure to the mixture. It is concluded that the evaluation of pollutants individually severely underestimates the environmental risk, and that the mixture of OCT and MPB exhibits synergistic or additive cytotoxic and genotoxic effects in A. cepa, mediated by oxidative stress, even at low concentrations.