Detection, characterization, and quantification of microplastics in human biological matrices: a systematic review

The presence of microplastics (MPs) in the environment represents an emerging risk to human health, with growing evidence of detection in human biological matrices. This systematic review synthesizes evidence on the detection, quantification, and characterization of MPs in human biological matrices. A systematic search was conducted in PubMed, Web of Science, and Scopus databases. Original research articles published in English up to 2025 that involved human participants were included, specifically selecting observational studies. The 40 included studies confirmed MPs in multiple human biological matrices, including blood, urine, feces, placenta, breast milk, semen, lung, and heart tissue. The Newcastle-Ottawa Scale (NOS) was used to assess the quality and risk of bias of the individual studies. Substantial methodological heterogeneity was observed in analytical techniques, including Fourier-transform infrared microspectroscopy (μFTIR), micro-Raman spectroscopy (μ-Raman), laser direct infrared spectroscopy (LDIR), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), as well as in the reporting units and limits of detection. Most studies reported fragments and fibers, with a predominance of polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET). NOS assessment showed that 52.5% of studies were of moderate quality, indicating that while the frequent detection of these particles suggests widespread human contact, significant methodological shortcomings and potential analytical overestimations limit the accurate quantification of systemic exposure and the strength of causal inferences. The widespread detection of MPs raises public health concerns regarding chronic exposure and potential health implications. However, current evidence remains insufficient to establish causal relationships, underscoring the urgent need for rigorous epidemiological studies.