Microplastics in the Human Body: What Current Research Shows

The question of whether microplastics harm human health is one of the most actively studied in environmental medicine right now. The answer is complex: we have substantial evidence that microplastics are present in human tissue, emerging evidence of associated health outcomes, and significant uncertainty about exposure thresholds and causation. This article summarises the state of the evidence as of 2025.

The short answer

Microplastics are now found in human blood, lungs, colon, placenta, breast milk, and testes. The particles cross biological barriers that were previously assumed to be more protective. In 2024, a major Italian study found that patients with microplastic-containing arterial plaque had a 4.5-fold higher rate of heart attack, stroke, or death over three years compared to patients without detectable microplastics in plaque. A separate 2024 study found higher microplastic concentrations in human testicular tissue were associated with lower sperm counts. These are association studies — they cannot yet prove causation — but the findings are prompting urgency in the research community that was not present five years ago.

Where microplastics have been found in human tissue

Blood

A 2022 study in the Netherlands (Environment International, Leslie et al.) detected microplastics in 77% of blood samples from 22 healthy adult volunteers. The particles detected included PET, polystyrene, and polyethylene. This was significant because blood circulation represents a transport mechanism — particles in blood can reach any organ.

Lungs

A 2022 UK study (Jenner et al., Science of the Total Environment) found microplastics in 11 of 13 lung tissue samples, including in the deeper lung regions (lower lobes). Fibres found included polypropylene, PET, and nylon. Inhalation of airborne fibres from synthetic textiles — particularly during laundering, storage, or wear — is one likely pathway.

Placenta

A 2021 Italian study (Ragusa et al.) detected microplastics in all six human placental samples examined — on both the foetal and maternal sides of the placenta. This indicates the particles cross the placental barrier. The implications for foetal exposure have driven significant research interest since publication.

Testicular tissue

A 2024 study (Science of the Total Environment, Zhao et al.) analysed testicular tissue from 23 men and found microplastics in all samples. The study found a statistically significant inverse correlation between microplastic concentration in tissue and sperm count. Polyethylene was the most common type detected.

Arterial plaque

A 2024 study in the New England Journal of Medicine (Marfella et al.) examined carotid plaque removed during endarterectomy. Patients with detectable microplastics or nanoplastics in their plaque had a significantly higher rate of heart attack, stroke, or all-cause death over 34 months of follow-up (hazard ratio approximately 4.5). This is the study that moved microplastic health evidence from tissue-presence findings into clinical outcomes.

Mechanisms of potential harm

Several mechanisms have been proposed for how microplastics might cause harm:

• Physical irritation: Plastic particles are foreign bodies. In tissue, they can trigger chronic low-grade inflammation, the same mechanism linked to atherosclerosis and other chronic diseases.
• Chemical burden: Plastic particles adsorb pollutants from their environment — pesticides, heavy metals, flame retardants, plasticisers (including phthalates and BPA). When microplastics are absorbed into tissue, they may release these co-contaminants at the absorption site.
• Endocrine disruption: Many plasticisers added to synthetic materials to make them flexible are known endocrine disruptors. Bisphenols and phthalates have been detected leaching from microplastics in laboratory studies.
• Oxidative stress: Cell studies have found microplastic exposure increases reactive oxygen species and markers of oxidative stress in human cells.

What the regulatory and scientific bodies say

The WHO's 2019 report on microplastics in drinking water stated the evidence was insufficient to characterise risk at then-current exposure levels, while calling for urgent research. In 2023 and 2024, multiple national health agencies updated their positions to note increasing concern based on accumulating tissue-level evidence. None have established specific exposure limits for microplastics — largely because measurement methodology is still being standardised and long-term dose-response data in humans does not yet exist.

The absence of a defined safe exposure limit is not the same as confirmation of safety. It reflects the immaturity of the evidence base relative to the pace of accumulation.

What to do

1. Reduce high-frequency sources of synthetic fibre exposure. Clothing is a major source of airborne and dermal microplastic exposure in addition to waterway pollution. Switching high-wash items to natural fibres reduces ongoing exposure. See the natural fibre clothing collection.
2. Reduce plastic food and water contact. Microplastics in food and water are a significant ingestion pathway. Glass and stainless containers reduce exposure from packaging.
3. Use a laundry filter. Captures fibres before they enter the water supply that eventually reaches drinking water. See How to Reduce Microplastics from Laundry.
4. Pay particular attention if pregnant or trying to conceive. The placental and testicular findings make this a priority group for precautionary action. See Microplastics and Fertility: What We Know.

Related guides

• Microplastics in Clothing: The Complete Guide
• What Are Microplastics and Why Do They Matter?
• Microplastics and Fertility: What We Know and What It Means
• PFAS in Everyday Products: The Complete Guide