Features,\nPotential Invasion Pathways, and Reproductive\nHealth Risks of Microplastics Detected in Human Uterus

Microplastics\n(MPs) are ubiquitous in global ecosystems and may\npose a potential risk to human health. However, critical information\non MP exposure and risk to female reproductive health is still lacking.\nIn this study, we characterized MPs in human endometrium and investigated\ntheir size-dependent entry mode as well as potential reproductive\ntoxicity. Endometrial tissues of 22 female patients were examined,\nrevealing that human endometrium was contaminated with MPs, mainly\npolyamide (PA), polyurethane (PU), polyethylene terephthalate (PET),\npolypropylene (PP), polystyrene (PS), and polyethylene (PE), ranging\nfrom 2–200 μm in size. Experiments conducted in mice\ndemonstrated that the invasion of the uterus by MPs was modulated\neither through diet–blood circulation (micrometer-sized particles)\nor via the vagina–uterine lacuna mode (larger particles reaching\na size of 100 μm. Intravenous exposure to MPs resulted in reduced\nfertility and abnormal sex ratio in mouse offspring (P < 0.05). After 3.5 months of intragastric exposure, there was\na significant inflammatory response in the endometrium (P < 0.05), confirmed by embryo transfer as a uterine factor leading\nto decreased fertility. Furthermore, human endometrial organoids cultured\nwith MPs in vitro exhibited significantly apoptotic\nresponses and disrupted growth patterns (P < 0.01).\nThese findings raise significant concerns regarding MP contamination\nin the human uterus and its potential effects on reproductive health.