Microplastic Contamination of Human Sperm before In Vitro Fertilization Warrants Attention for Early Life Exposure Risks

The global prevalence of infertility boosts the demands for assisted reproduction technology (ART) and medical plasticware for processing human reproductive cells. The direct exposure risks of these cells to microplastic (MPs) potentially released from the plasticware, especially when sperm is extracted by mincing testicular tissues with sharp tools, remain unknown. Also, there are methodological challenges in confirming the actual occurrence and visualizing the original morphology of MPs in the retrieved sperm samples. Here, we identified sub-10-μm polystyrene (PS) MPs with protein coronas in mechanically retrieved sperm specimens on PS plastic Petri dishes through optical photothermal infrared imaging. The particles were mainly generated by the tools that induced local polymer cutting deformation on the dishes, and a few originated from resin particles remaining on the dishes during manufacture. Each 5 mm scratch by the tools could produce 2.0-13 MPs (1.9-560 μm), depending on the extent of surface damage to the dishes. Most of the MPs (41.7-81.5%) derived from scratching could be retrieved along with sperm cells, with an estimated exposure dose of 100-22,000 particles/mL. We offered reliable evidence of direct human sperm exposure to MPs and advocate limiting plasticware use to reduce early life health risks for ART-conceived babies.