The findings should trigger alarm, says lead doctor in new study

At Green Prophet, we’ve been sounding the alarm on microplastics for over a decade. From plastic toothbrushes to disposable water bottles and even the invisible fragments shed by plastic teeth aligners, these tiny pollutants are everywhere—and they’re making their way into the most vital parts of our bodies, including our brains.

Plastics have infiltrated the planet’s most remote places, from the depths of the Mariana Trench to fresh Antarctic snow. They are in the dust of the Mojave Desert. Now, scientists are uncovering just how deeply they’ve infiltrated us. Research has revealed microplastics in human lungs, kidneys, and even the bloodstream.

But one of the most concerning discoveries yet? The presence of microplastics in the human brain and in some people if you put it together, it’s about the size of a crayon.

A recent study in Nature by toxicologist Matthew Campen at the University of New Mexico found that human brain tissue contains significant amounts of microplastics. By dissolving brain tissue samples, Campen’s team was able to isolate up to 10 grams of microplastics per brain—about the weight of a crayon. These findings highlight a grim reality: the plastics we ingest, inhale, and absorb from everyday products don’t just pass through our bodies; they accumulate in our organs, including the brain.

“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,” he says.

Scientists are racing to determine what microplastics do once they reach the brain. Early research suggests they may contribute to neuro-inflammation, cell death, and disruptions in brain function. Some studies even point to potential links between microplastics and neurological disorders like Alzheimer’s disease and dementia, though more research is needed to confirm these risks.

Made a brain goo and pulled plastic from the slurry

The researchers chemically dissolved the brain tissue, creating a kind of slurry, then ran it through a centrifuge, which spun out a small pellet containing undissolved plastic. The pellet was then heated to 600 degrees Celsius, a process known as pyrolysis. The researchers captured gas emissions as the plastics burned. Ions derived from the combusted polymers were separated chromatographically and identified with a mass spectrometer.

The technique detected and quantified 12 different polymers, the most common of which was polyethylene, which is widely used for packaging and containers, including bottles and cups.

“Dose makes the poison,” says Campen, adding that the new results should give rise to alarm about a global threat to human health. He acknowledges it can be hard to motivate consumers, who often shrug when warned about environmental contaminants that tend to be measured in parts per billion.

But the new findings might finally get their attention, he said. “I have yet to encounter a single human being who says, ‘There’s a bunch of plastic in my brain and I’m totally cool with that.’”

The team also used transmission electron microscopy to visually examine the same tissue samples that had high polymer concentrations – and found clusters of sharp plastic shards measuring 200 nanometers or less – not much larger than viruses. These are small enough to cross the blood-brain barrier, although Campen says it is unclear how the particles are actually being transported into the brain.

Are heart stents, fake breasts and artificial joints adding to the problem?

It is also unclear what effects plastic, which is considered to be biologically inert and used in medical applications like heart stents and artificial joints, might be having, he said. The physical characteristics of these particles may be the real problem, as opposed to some sort of chemical toxicity.

“We start thinking that maybe these plastics obstruct blood flow in capillaries,” Campen said. “There’s the potential that these nanomaterials interfere with the connections between axons in the brain. They could also be a seed for aggregation of proteins involved in dementia. We just don’t know.”

He suspects that most of the microplastics in the body are ingested through food – particularly meat, because commercial meat production tends to concentrate plastics in the food chain. A great deal of plastic is used in drip irrigation, and in hydroponics, furthering the sustainability question of this kind of “futuristic” food production. Netafim started developing compostable drip pipes a decade ago but jumps in innovation in this area have not been reported.

“The way we irrigate fields with plastic-contaminated water, we postulate that the plastics build up there,” Campen said. “We feed those crops to our livestock. We take the manure and put it back on the field, so there may be a sort of feed-forward biomagnification.”

The team has found high concentrations of plastic in meat bought at grocery stores, he added.

Where Are These Microplastics Coming From?

The plastic in your daily routine could be a major culprit. Here are some common sources:

• Plastic Teeth Aligners: Popular alternatives to metal braces, these aligners constantly shed microscopic plastic fragments as they wear down in the mouth.
• Toothbrushes: Most toothbrushes are made of plastic, and over time, bristles and handles break down into microplastics that can be ingested or washed into water systems.
• Water Bottles: Single-use and even reusable plastic bottles leach microplastics into the water you drink, particularly when exposed to heat.
• Food Packaging: Many processed foods come in plastic packaging that releases microplastics into food, especially when heated.
• Air Pollution: Microplastics are not just ingested—they are also inhaled. Synthetic clothing, car tires, and industrial waste contribute to airborne microplastic pollution.

The Health Risks: What We Know So Far

While research on microplastics in the human body is still emerging, initial findings are troubling:

Microplastics in the brain could interfere with cognitive functions, potentially contributing to neurodegenerative diseases.

A groundbreaking 2024 study from Harvard found that 60% of heart surgery patients had microplastics in their arteries. Those with plastic particles were 4.5 times more likely to suffer heart attacks, strokes, or death.

Microplastics have been found to trigger immune responses, leading to chronic inflammation.

Many plastics contain endocrine-disrupting chemicals (EDCs), which can interfere with hormone regulation and reproductive health.

How to avoid microplastics

Reducing exposure to microplastics is challenging but not impossible. Here are some steps you can take:

• Use a stainless steel or glass water bottle instead of plastic.
• Switch to old fashioned steel braces
• Switch to a natural, biodegradable or bamboo toothbrush.
• Choose ceramic or stainless steel food containers over plastic ones. A great way to start buying handmade dishes! Avoid or question products from countries like China where glaze testing is unreliable.
• Avoid heating food in plastic packaging.
• Invest in a high-quality air purifier to reduce airborne plastic particles indoors.
• Support policies that limit plastic production and pollution.
• Use natural, biodegradable plastics for wrapping food