Sex-specific toxicological observations following 28-day oral gavage exposure to spherical and milled polystyrene nano- and microplastic particles in mice

Abstract

Abstract Background With the rise in global plastic production, microplastics are an emerging environmental pollutant due to their ubiquitous presence in the environment. Human exposure and the impact of microplastics on human health warrants further research. Recent studies have confirmed the presence of microplastics in human tissues and several studies have noted toxicity in mammalian in vitro and in vivo models. In this 28-day gavage study, we investigated the effects of spherical and milled polystyrene nano- and microplastics in both male and female C57BL/6 mice. Results The results showed no significant changes in food consumption, body weights or organ weight coefficients. Additionally, there were no changes in hematological or clinical biochemistry parameters. Histological analysis revealed inflammation in the gallbladder of 9 male mice out of 23 and 2 female mice out of 24 exposed to both spherical and milled polystyrene. The adaptive and innate immune markers showed no major changes; however, pro-inflammatory cytokines were decreased in all polystyrene exposed males. Conversely, female mice exposed to both spherical and milled polystyrene showed mild pathological changes in the small intestine, with changes in goblet cell population and mucus production. The presence of polystyrene was detected in both the liver and intestines of both sexes. Conclusions Sphereical and milled polystyrene particles showed similar toxicological results, but sex-associated differences were noted. Therefore, further research is warranted to explore the potential sex-specific response to microplastic exposure.