A realistic combined exposure scenario: effect of microplastics and atrazine on Piaractus mesopotamicus

Abstract

Microplastics, considered emerging environmental contaminants resulting from plastic degradation, are discovered in diverseaquatic ecosystems and can be unintentionally ingested by fish. Therefore, it is essential to characterize their interaction withother contaminants, such as agrochemicals, in aquatic environments. This study aimed to assess histological, enzymatic, andgenotoxic biomarkers in juvenile pacú (Piaractus mesopotamicus) exposed to polyethylene (PE) microplastic particles andthe herbicide atrazine, individually or combined, for 15 days. Four treatments were used: a negative control (CON), PE inthe fish diet (0.1% w/w, FPE), atrazine through water (100 μg L-1, ATZ), and the mixture (ATZ+FPE). Results confirmedhistological alterations in gills (edema and lamellar fusion) and liver (necrotic areas and congestion) of fish exposed to ATZand ATZ+FPE. The number of goblet cells increased in the posterior intestine of fish under ATZ+FPE compared to CON andFPE. Enzyme activities (CAT, GST, AChE, and BChE) significantly increased in ATZ+FPE compared to CON. However, no genotoxic effect was demonstrated. These findings provide insights into the complex impacts of simultaneous exposureto atrazine and microplastics, emphasizing the need for continued research to guide effective environmental managementstrategies against these contaminants that represent a risk to aquatic organisms.