ONE WILD WORLD — NEWSLETTER

Issue #028   ·   Things Companies   ·   June 2026

A 2025 study found microplastics in every human brain tested — at concentrations 50% higher than eight years ago, crossing the blood-brain barrier, and present at five times the rate in people who died with dementia. A 2024 study in the New England Journal of Medicine found that people with plastic particles in their arterial plaque were 4.5 times more likely to have a heart attack, stroke, or die. And the industry that created this problem spent decades and tens of millions of dollars convincing you that sorting your recycling bin was the solution.

Microplastics are pieces of plastic smaller than five millimetres. Nanoplastics are smaller still — invisible to the naked eye, thin enough to slip through cell membranes, small enough to cross the barrier that protects the brain from most foreign particles. For most of the past two decades, scientists debated whether these particles were really getting into the human body. That debate is now closed. The question is what they do once they are there.

The Body Map

Microplastics have now been detected in human lungs, in bone marrow, in arterial plaque, in the liver, in the kidneys, in breast milk, in semen, in the placentas of unborn children, and in every testicle sample tested in a 2023 study. They have been found in the blood. They have been found in saliva and urine. They have been found in the olfactory bulb — the brain structure directly behind the nose, one of the most likely entry points for airborne particles.

The first time a lot of people heard about microplastics, it was in the context of ocean pollution and fish. The fish story was true, but it was also a useful framing for an industry under pressure: the plastic problem was out there, in the water, in the wildlife, an environmental issue for scientists in waders. The body story is different. The body story is that the particles are already in you, in concentrations high enough to measure, in organs you would prefer to keep clean.

In January 2025, researchers at the University of New Mexico published a study in Nature Medicine that put a number on something researchers had been dreading. They chemically dissolved brain tissue from autopsy samples — frontal cortex, the region just above and behind the eyes — and measured what was left after the human material had been broken down. What remained, in every sample, was plastic.

The samples came from two groups: people who died in 2016, and people who died in 2024. The concentration in the 2024 brains was about 50% higher. The 2024 brains were, on average, 0.5% plastic by weight. That is roughly the equivalent of a small plastic spoon’s worth of material for every 100 grams of brain tissue. The researchers then extended the comparison back further, pulling samples from 1997 to 2013. The increase over time was consistent. Plastic concentrations were more than double in 2016 compared to the late 1990s, and almost four times higher in 2024.

The researchers also tested the brains of twelve people who died with a dementia diagnosis. Their brains contained more than five times the microplastic concentration of the healthy 2024 samples. The study is explicit about what this finding means and does not mean: it is an association, not a cause. Dementia patients may have impaired ability to clear particles. Or higher exposure may contribute to neurodegeneration. Or both. Or neither. The study does not answer this. It documents the association and leaves the rest for future research.

"I never would have imagined it was this high. I certainly don’t feel comfortable with this much plastic in my brain, and I don’t need to wait around 30 more years to find out what happens if the concentrations quadruple."

— Matthew Campen, lead researcher, University of New Mexico (2025)

The brain study got headlines, but the study with the most immediate clinical implications was published a year earlier. In March 2024, a team of Italian researchers published a prospective study in the New England Journal of Medicine. They had taken samples of arterial plaque from 257 patients undergoing surgery to remove blockages from their carotid arteries — the arteries in the neck that supply blood to the brain. The plaque was tested for microplastics.

Polyethylene was found in the plaque of 58% of patients. Polyvinyl chloride was found in 12%. The researchers then followed all 257 patients for an average of 34 months. At the end of the follow-up period, the rate of heart attack, stroke, or death from any cause was 4.5 times higher in patients whose plaque had contained microplastics than in those whose plaque had not.

The caveats are important here. The study is observational. People whose arteries contain more plastic may differ in other ways from those whose arteries contain less — diet, occupation, geography, exposure history — and some of those differences may explain the outcomes. The study cannot prove that the plastic caused the events. What it can say, and does say, is that the association is large, statistically significant, and published in one of the most rigorous medical journals in the world.

This is the Things Companies section. The science above tells you what is in your body. This part tells you how it got there, and specifically what the people responsible for putting it there have been doing for the past fifty years.

In 1953, Vermont briefly banned disposable bottles after dairy farmers complained that broken glass in fields was killing livestock. The beverage and packaging industries mobilised. They founded Keep America Beautiful — a seemingly civic-minded nonprofit, one of the most effective pieces of corporate lobbying infrastructure ever built. The organisation’s famous "litterbug" advertising campaigns, launched in the late 1950s, delivered a precise message to the American public: pollution was a personal failing. The structural driver — the industry producing ever-increasing volumes of disposable packaging — was carefully kept out of frame.

The campaign worked. Picking up rubbish became a moral duty. “Recycling” became the expected response. Keep America Beautiful’s corporate partners included Coca-Cola, Pepsi, Nestle, and the major plastic producers. While the organisation promoted individual responsibility for waste, its backers were simultaneously lobbying against container-deposit legislation — the bottle-bill laws that would have made companies responsible for taking back their own packaging.

In 1988, the industry introduced the Resin Identification Code: the small numbered triangles printed on plastic products, designed to look like recycling symbols. Most of the plastics that carried those symbols were not actually recyclable in any economically viable way. Internal documents from the same period confirm that the industry knew this. According to NPR’s 2020 investigation drawing on those documents, industry officials had known since the 1970s that large-scale plastic recycling was economically unviable, because the process costs more than making new plastic from oil.

In 1989, the Society of the Plastics Industry convened a private meeting in Washington. Executives from Exxon, Chevron, Amoco, Dow, DuPont, and Procter & Gamble attended. The problem on the table was plastics’ deteriorating public image. The solution they settled on, according to Lew Freeman, who was vice president of the lobbying group at the time, was: “advertise our way out of it.” What followed was a $50 million-a-year ad campaign promoting the benefits of plastic and the promise of recycling. The campaigns ran for years. Less than 10% of all plastic ever produced has been recycled.

The industry knew recycling was not a real solution. They spent $50 million a year promoting it anyway. The alternative — less plastic — was not on the agenda.

It would be dishonest to write this newsletter without being clear about what the science has not yet established. The presence of microplastics in human organs is documented. The health consequences are not.

The dementia association in the 2025 Nature Medicine study is not a causal finding. The cardiovascular association in the 2024 NEJM study is not a causal finding. Animal studies — particularly in mice — have shown that microplastics can drive arterial plaque formation and inflammation at environmentally relevant doses. But the jump from mouse models to human disease mechanisms is not automatic, and it has not yet been made with the kind of evidence that would satisfy a clinical standard of proof.

The honest summary is this: the particles are in your body, in concentrations that are increasing with time, in organs including the brain. We have biological plausibility for harm — plastic particles and their chemical additives can cause inflammation, disrupt hormones, and damage cells in laboratory conditions. We have epidemiological associations between plastic burden and serious health outcomes. We do not yet have the large, long-term, prospective human trials that would establish the causal chain beyond doubt.

Matthew Campen, whose team published the brain study, put it directly: “I certainly don’t feel comfortable with this much plastic in my brain, and I don’t need to wait around 30 more years to find out what happens if the concentrations quadruple.” That is not a scientific conclusion. It is a reasonable human response to a body of evidence that is building faster than anyone expected.

The plastic is in your brain. It was in the brain of every person in the study.

The concentration in 2024 was 50% higher than in 2016.

In 1989, the industry that made it decided to advertise their way out of the problem.

They are still advertising.

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SOURCES

Campen, M. et al. — "Bioaccumulation of microplastics in decedent human brains", Nature Medicine (2025). DOI: 10.1038/s41591-024-03453-1

Marfella, R. et al. — "Microplastics and nanoplastics in atheromas and cardiovascular events", New England Journal of Medicine, 390:900–910 (2024). DOI: 10.1056/NEJMoa2309822

Clark, R. et al. — "Micronanoplastics in carotid artery plaque in symptomatic patients", presented at AHA Vascular Discovery Scientific Sessions, Baltimore (April 2025)

Ragusa, A. et al. — "Plasticenta: First evidence of microplastics in human placenta", Environment International (2021)

Schwabl, P. et al. — "Detection of various microplastics in human stool", Annals of Internal Medicine (2019)

Leslie, H.A. et al. — "Discovery and quantification of plastic particle pollution in human blood", Environment International (2022)

Ragusa, A. et al. — "Deeply understanding human exposure to micro and nanoplastics", Polymers (2021) — breast milk

Zhao, Z. et al. — "Widespread microplastic pollution in human testes", Science of the Total Environment (2023)

NPR / Frontline — "How Big Oil Misled the Public into Believing Plastic Would Be Recycled" (2020)

DeSmog — "Proof Plastics Industry Knew Recycling Was False Solution in 1974" (2025) — internal industry documents

US Environmental Protection Agency — Plastics: Material-Specific Data (less than 10% historical recycling rate)

Keep America Beautiful — corporate history and founding documented in: Strand, G. — "The Crying Indian", Orion Magazine (2008)

Freeman, L. — quoted in NPR/Frontline investigation (2020): "advertise our way out of it"

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