Unveiling the presence of micro and nanoplastics in human biological matrices: A systematic review covering the latest five years from 2020 to 2025.

Plastic contamination has emerged as one of the most pressing environmental challenges of the 21st century, with global plastic production surpassing 413 million metric tons in 2024. This dramatic increase has led to a parallel rise in the generation of micro- and nanoplastics (MNPs), tiny plastic particles that now permeate not only natural ecosystems but also human environments. Human exposure to MNPs occurs through contaminated food, water, inhalation of airborne particles, dermal contact, and medical devices, although the exact exposure levels and health impacts remain uncertain. Once internalized, these particles have been shown to provoke inflammation, oxidative stress, and immune system disruption. To better understand the scope of this issue, a systematic review was conducted in accordance with PRISMA guidelines. Data were extracted on polymer types, particle sizes, detection methodologies, and documented biological impacts. MNPs were consistently identified across a wide range of human biological matrices, with the blood (30.2 %), stool (12.3 %), and skin (9.9 %) being among the most frequently studied. The most detected polymers included polyethylene (PE), polypropylene (PP), and polystyrene (PS). Recent advancements in detection technologies, particularly micro-Raman spectroscopy (μRaman), micro-Fourier Transform Infrared spectroscopy (μFTIR), and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS), have significantly enhanced analytical sensitivity, allowing for the reliable identification of particles as small as 1 μm. Without limitation the results from this systematic review are useful and applicable to guiding public health policies, shaping environmental regulations, and informing future toxicological research.