Microplastics from disposable paper cups are enriched in the placenta and fetus, leading to metabolic and reproductive toxicity during pregnancy

Abstract The health implications of microplastics (MPs), especially those originating from hot drinks in disposable paper cups (DPCs), are increasingly alarming. We investigated the accumulation and metabolic and reproductive toxicological effects of MPs from DPCs filled with hot water in various tissues in a pregnant mouse model. Simulating human intake of 0.3, 3.3, and 33.3 cups daily, we found MPs exposure-induced dose-responsive harmful effects on murine fetal development and maternal physiology. MPs were detected in all 13 examined tissues, with the highest accumulation in the cecal contents, followed by significant depositions in the fetus, placenta, kidney, spleen, lung, and heart. A higher proportion of smaller MPs (90.35% < 10 μm) was identified in brain tissues. Dose-responsive changes in functional microbiome and gene pathways were observed. Moderate MPs intake of 3.3 cups daily significantly altered cecal microbiome composition and metabolic functions. The transcriptomic functional variations in maternal blood, placenta, and mammary gland underscore the significant impacts of realistic MPs exposure on metabolic and immune health and posing neurodegenerative and miscarriage risks. The benchmark dose framework analysis using tissue-specific gene biomarkers revealed safe exposure limits at 2 to 4 cups/day during pregnancy. Our results indicate selective tissue accumulation and potential metabolic and reproductive toxicities of MPs at exposure levels presumed non-hazardous. Such risks remain unaddressed within current food safety regulations, impacting vulnerable groups such as pregnant women and fetuses. Research Highlights Microplastics released from disposable paper cups filled with hot water showed preferential accumulations in the murine fetus, placenta, kidney, spleen, lung, and heart, with significant adverse impacts on fetal development. Microplastic exposure led to dose-responsive maternal microbiome changes associated with increased fatty acid biosynthesis and elevated expressions of genes related to viral infections, neurodegenerative diseases, oxidative stress, and miscarriage risk. A consumption level of 3.3 cups/day was sufficient to elicit systemic metabolic and reproductive toxicity, with a predicted safe exposure limit of 2 to 4 cups/day during pregnancy by benchmark dose framework analysis with molecular biomarkers.