Global plastic pollution is a significant environmental and public health concern. Plastic production has increased since the 1950s, reaching approximately 368 million metric tons in 2019. Approximately 60% of all plastics ever produced are disposed of, leading to pervasive contamination of our ecosystem with microplastic particles. Microplastics are a concern for public health given their resistance to degradation, presence in air, food and products relevant to human exposure, and demonstrated ability to cross cell membranes. Human exposure via inhalation and ingestion is unavoidable with recent evidence-based estimates suggesting humans intake tens of thousands of microplastic particles annually, or on the order of several milligrams daily. Understanding the extent to which microplastics are absorbed is a critical next step in evaluating their relevance to human health. The overarching aim of this research is to translate methods that have been developed for measuring microplastics in environmental samples and marine tissues for use with human biospecimens. Specifically, by leveraging the relatively accessible placenta, we propose an approach to measure and characterize microplastics in tissue collected from the general population of pregnant people. We will also investigate sources of exposure, including modifiable lifestyle factors, as well as sources of contamination present in the labor and delivery room and during sample processing. The proposed research will leverage existing infrastructure from the N (NYU CHES), an ongoing prospective birth cohort designed to study prenatal exposure to endocrine disrupting chemicals on a range of perinatal and child health outcomes. Maternal urinary concentrations of bisphenol and phthalate chemicals will also be measured during pregnancy. This will allow us to examine patterns of joint exposure to chemical plastic additives and plastic particles. In sum, we anticipate results from this research will provide critical insights on the extent to which humans are exposed to microplastics. This information may significantly alter our view of plastics as inert particles that pass through the human system and lead to a reassessment of the risks posed by microplastics exposure.