Microplastic ingestion induces behavioral disorders in mice: A preliminary study on the trophic transfer effects via tadpoles and fish.

In this study, the hypothesis that polyethylene microplastics (MPs) can accumulate in animals, reach the upper trophic level and trigger behavioral changes was tested. Physalaemus cuvieri tadpoles were exposed to MPs (for 7 days) and fed on tambatinga fish for the same period. Subsequently, these fish were given as food to Swiss mice. The MP amount in animals' liver was quantified and results have evidenced its accumulation at all assessed trophic levels [tadpole: 18,201.9 particles/g; fish: 1.26 particles/g; mice receiving tambatingas who had fed on tadpoles exposed to MPs: 57.07 particles/g and mice receiving water added with MPs: 89.12 particles/g). Such accumulation in the last group was associated with shorter traveled distance, slower locomotion speed and higher anxiety index in the open field test. Mice receiving tambatingas who had fed on tadpoles exposed to MPs were confronted to a potential predator and showed responses similar to those of animals who had ingested water added with MPs (lack of defensive social aggregation and reduced risk assessment behavior). Thus, results have preliminarily confirmed the initial hypothesis about how MPs in water can reach terrestrial trophic levels and have negative impact on the survival of these animals.