Enhanced reproductive toxicities induced by phthalates contaminated microplastics in male mice (Mus musculus)

It has been demonstrated that microplastics (MPs) can transport phthalate esters (PAEs) into the tissues of mice. However, the influence of MPs on accumulation of PAEs and the combined toxicity need profound investigation. In this study, the bioaccumulation of PAEs and reproductive toxicity due to contaminated MPs exposure were investigated. After exposure to PAE-contaminated MPs for 30 days, significantly increased accumulation of PAE was observed in the liver and gut but not in the testis, which are ascribed to the distribution of MPs in tissues. Herein, most micro-size MPs accumulated in the gut and liver, while only a few nano-size MPs entered the Sertoli cells. Compared with virgin MPs and PAEs alone, PAE-contaminated MPs induced enhanced reproductive toxicities manifested by greater alterations in sperm physiology and spermatogenesis. The enhanced toxicities were also confirmed by the testicular transcriptomic alterations and aggravated oxidative stress induced by PAE-contaminated MPs. These aggravated reproductive toxicities were not caused solely by PAE, but may also be caused by the sensitization effect of oxidative stress induced by MPs. Our results highlight the potential reproductive toxicity on male terrestrial mammals due to co-exposure of MPs and plastic additives and provide valuable insights into the mechanism of combined toxicity of MPs and other pollutants.