Interaction between polyethylene microplastic and 2,4-dichlorophenoxyacetic acid (2,4-D): chemical and ecotoxicological evaluation with Girardia tigrina

The presence of microplastics (MPs) in aquatic and terrestrial ecosystems and their consequences on biota have received considerable attention in recent years. However, the effects of the interactions between these materials and other pollutants still need to be better understood. This study, therefore, aimed to evaluate the effects of two different treatments (MP and MP + 2,4-D herbicide) in (Girardia tigrina) as a test organism. The treatment was carried out to simulate the natural wear of the material, which was done by chemical oxidation and solar irradiation. The chronic effects on locomotion, regeneration, and reproduction in G. tigrina were evaluated after ingesting MP-treated and MP-treated + 2,4-D homogenized in the liver. The most significant effects were observed in the MP + 2,4-D treatment, with reduced fecundity (61%) and fertility (70.6%) of G. tigrina in relation to the control, increased locomotion speed (79.5%), delayed regeneration, auricles (46.1%) and photoreceptors (41.6%), therefore indicating greater risks of management practices with application of 2,4-D in areas with the presence of MP. These results show that the interaction between MPs and organic pollutants occurs after MP-PE has aged and that this combination promotes greater toxicity to this contaminant.