In 2022, a study published in Environment International provided the first direct evidence of microplastics in human blood. Researchers from the Vrije Universiteit Amsterdam tested blood samples from 22 healthy adults and found detectable microplastics in 17 of them, 77% of the sample. The plastics found included PET (polyethylene terephthalate, used in drinks bottles), polystyrene, and polyethylene. The study used a highly sensitive analytical technique to avoid contamination errors, making the findings methodologically robust.
The 2022 Amsterdam study
The study found microplastic concentrations ranging from 0 to 2.4 micrograms per millilitre of blood. PET was the most common polymer detected, which is consistent with PET's ubiquity in food and drink packaging. The researchers noted that the blood concentrations found were at the lower detectable limit of their methodology, meaning that actual concentrations may be higher and that the 23% of samples with no detected microplastics may simply reflect analytical limits rather than true absence. The study was small (22 participants) but was designed primarily to demonstrate feasibility and establish baseline methodology.
Subsequent research
Since 2022, microplastics have been confirmed in human lung tissue (2022), human placenta (2020, 2023), human breast milk (2022), human testicular tissue (2023), and most recently in human brain tissue. A 2024 study from the University of New Mexico, analysing post-mortem brain samples, found microplastics in every sample examined and at concentrations approximately ten times higher than those found in other organs, suggesting either preferential accumulation in brain tissue or a blood-brain barrier that is less effective at exclusion than previously assumed.
The 2024 New England Journal of Medicine study represented a significant escalation in concern. Researchers found microplastics embedded in the carotid arterial plaque of patients undergoing endarterectomy surgery. Patients whose plaques contained microplastics had a 4.5-fold higher risk of non-fatal heart attack, stroke, or death from any cause compared to patients with no detected microplastics in their plaques. This is the first study to establish a direct association between microplastic tissue accumulation and a hard clinical outcome.
What it means for health
The health implications of microplastic accumulation are not yet fully characterised. Known mechanisms include physical inflammation from particle irritation, chemical toxicity from plastic additive chemicals and adsorbed environmental toxins (microplastics are efficient carriers of PFAS, PCBs, and heavy metals), and potential interference with cellular processes at the nanoplastic scale where particles can cross cell membranes. The honest answer is that the scientific community is working quickly to characterise these effects and the full picture will likely take another decade to emerge. What is already clear is that microplastics accumulate in human tissue and that accumulation in arterial plaque is associated with serious adverse outcomes.
Reducing exposure
Drinking water is a primary source. Bottled water contains higher microplastic concentrations than filtered tap water in most studies. A water filter (reverse osmosis or solid block carbon) significantly reduces microplastic ingestion from water. Not heating food in plastic containers and switching from plastic to glass or stainless steel for food storage removes another major dietary source. Using a GuppyFriend bag when washing synthetic clothing captures a substantial proportion of fibres before they enter the water system. None of these measures eliminates exposure, but they reduce the daily accumulation rate.