First report on the toxicity of SARS-CoV-2, alone and in combination with polyethylene microplastics in neotropical fish

The COVID-19 pandemic has caused unprecedented negative impacts in the modern era, including economic, social, and public health losses. On the other hand, the potential effects that the input of SARS-CoV-2 in the aquatic environ-ment from sewage may represent on non-target organisms are not well known. In addition, it is not yet known whether the association of SARS-CoV-2 with other pollutants, such as microplastics (MPs), may further impact the aquatic biota. Thus, we aimed to evaluate the possible ecotoxicological effects of exposure of male adults Poecilia reticulata, for 15 days, to inactivated SARS-CoV-2 (0.742 pg/L; isolated SARS.CoV2/SP02.2020.HIAE.Br) and polyethylene MP (PE MPs) (7.1 x 104 particles/L), alone and in combination, from multiple biomarkers. Our data suggest that exposure to SARS-CoV-2 induced behavioral changes (in the open field test), nephrotoxic effect (inferred by the increase in cre-atinine), hepatotoxic effect (inferred by the increase in bilirubin production), imbalance in the homeostasis of Fe, Ca, and Mg, as well as an anticholinesterase effect in the animals [marked by the reduction of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity]. On the other hand, exposure to PE MPs induced a genotoxic effect (assessed by the comet assay), as well as an increase in enzyme activity alpha-amylase, alkaline phosphatase, and carboxylesterases. However, we did not show synergistic, antagonistic, or additive effects caused by the combined ex-posure of P. reticulata to SARS-CoV-2 and PE MPs. Principal component analysis (PCA) and values from the Integrated Biomarker Response index indicate that exposure to SARS-CoV-2 was determinant for a more prominent effect in the evaluated animals. Therefore, our study sheds light on the ecotoxicity of the new coronavirus in non-target organisms and ratifies the need for more attention to the impacts of COVID-19 on aquatic biota.

Automated summary

The COVID-19 pandemic has caused unprecedented negative impacts. The potential effects of SARS-CoV-2 and microplastics in the aquatic environment are not well known. This study evaluated the ecotoxicological effects of exposure to SARS-CoV-2 and polyethylene microplastics in male adult Poecilia reticulata. The results showed behavioral changes, nephrotoxic and hepatotoxic effects, imbalances in ion homeostasis, and anticholinesterase effects induced by SARS-CoV-2 exposure. Polyethylene microplastic exposure caused genotoxic effects and increased enzyme activity. The combined exposure did not show synergistic effects. The study highlights the need for attention to the impacts of COVID-19 on aquatic biota.