Microplastics in Human Biological Matrices: Forensic Integration of Toxicological and Medico-Legal Evidence

Microplastics (MPs) have emerged as a pervasive environmental contaminant with growing evidence of human internal exposure. Their persistence, ability to cross biological barriers, and potential c additives raise significant concerns in forensic toxicology and public health.

To critically synthesize global evidence on the occurrence, toxicokinetics, and forensic relevance of MPs detected in human biological samples, highlighting their potential value in medico-legal investigations.

A narrative review of over 40 peer-reviewed studies (2019–2024) was undertaken using PubMed, Scopus, and Web of Science. Studies reporting MPs in human matrices, including blood, placenta, breast milk, lungs, feces, urine, semen, thrombi, and cerebrospinal fluid, were evaluated for analytical methods, particle characteristics, and quality-control rigor.

MPs were consistently detected in 12 different human matrices, with particle sizes ranging from <1 µm to 500 µm, predominantly as fibers and fragments of polyethylene, polypropylene, and polyethylene terephthalate. Documented biological effects include oxidative stress, inflammation, immune dysregulation, and possible neurotoxicity. From a forensic perspective, polymer-specific signatures and pigment residues can serve as trace indicators of exposure, supporting medico-legal investigations in cases of environmental or occupational disease.

The detection of MPs in human biological samples underscores their dual toxicological and forensic significance. Standardized analytical protocols and forensic validation are essential to ensure evidentiary reliability and to interpret microplastic exposure in a medico-legal context.