Toxicological Evaluations Following 28-Day Oral Gavage Exposure to Polyethylene Terephthalate Microplastic Particles in Mice

The degradation of plastic in the environment can result in the generation of micro- and nano-plastics. As one of the common types of plastics used, polyethylene terephthalate (PET) microplastics are pervasive in the environment. Yet, their potential toxicity remains poorly understood. In this study, we addressed this gap by examining systemic toxicity in C57BL/6 mice following 28-day oral gavage with irregularly shaped PET microplastics at human-relevant exposure levels of 0, 0.3, 1.5, 7.5, or 37.5 mg/kg bodyweight/day. No significant changes were seen in bodyweights, food consumption, organ weights, clinical biochemistry, or hematological parameters. Histological changes were seen in the kidneys of male mice with minimum to mild apoptosis in the outer strip of the outer medulla. Additionally, decreased goblet cells were observed in both male and female mice, albeit in different intestinal sections. However, this change in goblet cell population did not result in overt epithelial damage. Overall, sub-chronic PET microplastic exposure did not cause overt systemic toxicity, but sex-specific minor histological alterations in the kidney and gut were observed. Our findings show only minor effects following short-term exposure, but real-world microplastic exposure is likely to be chronic, thus a longer exposure period may be necessary to fully elucidate the potential impact of PET microplastic-induced toxicity.