For decades, plastic pollution was something that happened out there — to turtles, to beaches, to that floating garbage patch you saw a documentary about once. That era is over. Between 2019 and 2025, researchers went looking for plastic inside human beings, and they found it essentially everywhere they looked.
This is the inventory. Every line cites a peer-reviewed study you can check at the bottom.
Blood (2022)
Dutch researchers analyzed blood from 22 healthy donors and found quantifiable plastic particles in 77% of them — PET (bottle plastic), polystyrene, and polyethylene, at an average concentration of about 1.6 micrograms per milliliter. This was the study that moved the conversation from “we might be ingesting plastic” to “it’s circulating in our veins.”
Brain (2025)
A team at the University of New Mexico analyzed brain tissue from autopsies and found micro- and nanoplastics in every sample — at concentrations suggesting roughly a plastic spoon’s worth (~7 grams) in a typical brain, mostly as nano-scale polyethylene shards. Two findings deserve your attention:
- Brains from 2024 contained about 50% more plastic than brains from 2016. The dose is rising, fast.
- Brains of people with documented dementia carried markedly higher concentrations. Important caveat: this is a correlation; diseased brains may simply clear particles worse. Nobody has shown plastic causes dementia.
Artery plaque (2024)
The most clinically serious finding to date. Italian surgeons followed 257 patients who had plaque removed from their carotid arteries. In about 58% of patients, the plaque contained detectable polyethylene or PVC. Over the next ~34 months, the patients with plastic in their plaque had a 4.5× higher risk of heart attack, stroke, or death than those without.
This was an observational study at one center — it shows association, not proof of cause. But it was published in the New England Journal of Medicine, the most conservative venue in medicine, with an editorial calling for urgent follow-up. This is not a fringe result.
Placenta (2021, confirmed 2024)
Italian researchers first detected microplastics in human placentas in 2021 — on both the maternal and fetal sides. In 2024, a University of New Mexico team using a more sensitive method found plastics in all 62 placentas they tested, every single one. The phrase researchers now use is “born pre-polluted.”
Lungs (2022)
UK researchers found microplastic fibers in 11 of 13 samples of living human lung tissue, including in the deepest regions of the lung — particles small enough to ride air currents all the way down.
Breast milk (2022)
Microplastics were detected in 26 of 34 samples of human breast milk. Before this becomes a guilt engine: breast milk remains unambiguously recommended; formula prepared in plastic bottles carries its own (larger, fixable) plastic dose. The lesson isn’t “don’t breastfeed” — it’s that nothing in the chain is plastic-free anymore.
Testes and semen (2024)
Microplastics were found in every human testis sampled in a 2024 study, and multiple 2024 studies found them in most semen samples tested. Whether this relates to the global decline in sperm counts is unproven — but the particles are sitting in the most hormone-sensitive tissue in the male body.
Stool, saliva, liver, kidneys (2019–2024)
The first human detection was stool in 2019 (all eight participants, from eight different countries). Liver, kidney, and salivary findings have followed in autopsy and clinical studies.
How to read this without spiraling
Three honest framings:
- Presence is established. Harm is emerging. That plastic is in these tissues is no longer debated. What it does there is an open scientific front — the strongest human signal so far is the cardiovascular study above.
- The dose is rising. The brain data suggests ~50% more plastic in eight years. Whatever the harm threshold turns out to be, we are moving toward it, not away.
- Your intake is adjustable. Autopsy studies measure people who never tried to avoid plastic — nobody told them bottled water averages a quarter-million particles per liter or that heating plastic multiplies shedding. You know. That’s the entire point of this site.
Start with the 30-Day Purge. It’s sequenced by impact, and week one is free.