Where Microplastics Have Been Found in the Human Body

Blood — first confirmed in 2022

In March 2022, Leslie and colleagues at Vrije Universiteit Amsterdam published the first study to detect and quantify microplastics in human blood. Whole blood samples from 22 healthy, non-fasting adult volunteers were analysed using pyrolysis–GC/MS. Plastic particles were detected in 17 of 22 participants (77%). The most common polymer was PET, detected in 50% of samples, followed by polystyrene (36%) and polyethylene (23%). Mean total concentration was 1.6 µg/ml¹.

This confirmed microplastics can enter systemic circulation — meaning they can, in principle, reach any organ in the body.

Arterial plaque — linked to cardiovascular events in 2024

Marfella and colleagues (2024) detected microplastics in carotid artery plaque specimens from patients undergoing endarterectomy. Using pyrolysis–GC/MS and electron microscopy, they found polyethylene in 58.4% of specimens and polyvinyl chloride in 12.1%. At 34-month follow-up, patients with microplastics in their plaque had a hazard ratio of 4.53 for the composite endpoint of MI, stroke, or death².

Testicles — detected in 100% of samples in 2024 study

Hu and colleagues (2024) analysed testicular tissue from both human and canine subjects using pyrolysis–GC/MS. Microplastics were detected in every human testicular sample examined, with a median concentration of 329.44 µg/g tissue — higher than concentrations found in dog testes. The most prevalent polymers were polyethylene, PVC, and PET⁷.

A separate 2024 multi-site study by Zhou and colleagues in eBioMedicineexamined 113 male participants across three regions of China. Microplastics were detected in semen samples and found to be associated with reduced sperm progressive motility; exposure to PTFE was specifically linked to lower sperm count⁸.

The placenta — unborn children exposed in utero

Ragusa and colleagues (2021) published the "Plasticenta" study — the first detection of microplastics in human placentas. Six placentas were collected from consenting women with uneventful pregnancies. Twelve microplastic fragments were found in four placentas using Raman microspectroscopy, on both the maternal and fetal sides³.

This finding confirmed that the placenta — previously considered a robust protective barrier — does not prevent microplastic passage to the developing fetus.

Breast milk — confirmed in 2022

Ragusa and colleagues (2022) published the first study to detect microplastics in human breast milk, examining 34 samples from healthy women with no occupational plastic exposure using Raman microspectroscopy. Microplastics were detected in 26 of 34 samples (76%)⁴.

Brain tissue — accumulates at higher concentrations than other organs

Post-mortem studies of human brain tissue have detected microplastic particles, with concentrations found to exceed those in liver and kidney samples from the same donors. This pattern of preferential brain accumulation is hypothesised to relate to the lipophilic properties of certain polymers and the brain's high fat content, though the mechanism has not been definitively established¹³.

Routes of entry into the body

Three primary exposure routes are established¹⁴:

• Ingestion — through food, water, and hand-to-mouth contact; the primary route
• Inhalation — airborne fibres from synthetic textiles, urban dust, and particulate pollution
• Dermal contact — direct skin absorption has been demonstrated for nanoplastics in laboratory conditions