Why Detecting Nanoplastics in Humans Matters: Exposure Routes, Biological Evidence, and Potential Health Implications

Nanoplastics, defined as plastic particles smaller than one micrometre, have emerged as a growing concern in human health research. Their small size allows them to cross biological barriers and interact directly with cells and tissues. Recent studies have confirmed the presence of plastic particles in multiple human biological matrices, including blood, lung tissue, placenta, faeces, urine, vascular tissue and brain samples. These findings indicate that human exposure to nanoplastics is not merely environmental but involves internal uptake. This review summarises current evidence on routes of human exposure and biological matrices, where nanoplastics have been detected, and potential health implications, on the basis of experimental and emerging clinical data. Ingestion and inhalation appear to be the dominant exposure pathways, with additional concern related to maternal-foetal transfer. Experimental studies suggest that nanoplastics may induce oxidative stress, inflammation, endocrine disruption and neurobiological effects, although direct causal links in humans remain limited. Accurate detection in clinical samples is essential for risk assessment and future epidemiological studies. While techniques such as pyrolysis gas chromatography–mass spectrometry (GC–MS), Raman spectroscopy, and single-particle inductively coupled plasma mass spectrometry (ICP–MS) have enabled recent discoveries, methodological limitations persist. Standardisation of analytical workflows is required before routine clinical interpretation can be achieved.