Combined Ingestion of Polystyrene Microplastics and Epoxiconazole Increases Health Risk to Mice: Based on Their Synergistic Bioaccumulation in Vivo

Both microplastics and pesticides are environmental pollutants that can be ingested by organisms and cause adverse reactions, but it is unclear whether they cause combine toxicity in mammals. In this study, polystyrene (PS) microplastics or/and epoxiconazole (EPO) were administered orally to mice for 6 weeks, their single and combined toxicity on mice were explored in terms of histopathology, oxidative defense system and metabolic profile, their bioaccumulation levels were also measured. The results showed that inflammatory cell infiltration and functional damage in liver were caused by polystyrene, in addition to the above-mentioned injury, hepatic oxidative stress and metabolic disorders of liver and kidney were also caused by epoxiconazole. Besides, more severe effects involving tissue damage, oxidative stress, and metabolic disorders in liver and kidney were observed under combined exposure to polystyrene and epoxiconazole, importantly, the combined toxicity appeared to be associated with increased levels of their bioaccumulation. In-depth research found that epoxiconazole caused intestinal barrier damage by targeting the gut microbiota, leading to massive invasion of polystyrene, which in turn interfered with hepatic metabolism of epoxiconazole. In all, our evidence indicated that polystyrene and epoxiconazole could cause combined toxicity in mammals through the synergistic effect of their bioaccumulation in vivo, which provided new insights into the health risks posed by microplastics and pesticides in mammals.