Two studies provide shocking new data about the nature of the threat posed to human health by microplastics—tiny, usually invisible, fragments that are produced when plastics degrade.
Billions of tonnes of plastic have been manufactured, mostly in the last two decades, and the vast majority of it has ended up in the environment, in our seas and oceans. There the plastic breaks down into smaller and smaller pieces that are capable of entering the bodies of animals and humans and wreaking various forms of havoc we have yet to fully comprehend. But what we do know is bad enough.
Microplastics circulate like a force of nature: they travel on ocean currents, they’re kicked up into the atmosphere by evaporation and waves, they float through the air, and they enter clouds and fall in snow and rain over vast territories, far from places human beings have ever set foot. One estimate claims 3,000 tonnes of microplastics fall in snow over Switzerland every year.
But it’s not just out there, in nature, that we’re exposed to microplastics. It’s also in our day-to-day lives, in our homes and workplaces. If we drink water in plastic bottles, we’re potentially consuming millions or billions of plastic pieces with each mouthful. Food wrapped in plastic or prepared using plastic will be contaminated, of course. Even our clothes and furnishings, if they’re made with synthetic fibres, shed microplastics that accumulate in dust around our homes. Every single day, we drink microplastics, we eat them, we inhale them—and we probably absorb them through our skin and even through soft-tissue surfaces like the eyeballs.
In short, microplastics are ubiquitous. There seems to be no way for us to avoid exposure to them, even if we lock ourselves in our own homes and never go out.
The real issue is what these tiny particles are doing to us. Could they be contributing to the explosion of ill health and chronic disease we’ve seen in recent decades, from obesity and diabetes, to cancer, reproductive issues and neurological conditions like Alzheimer’s? The answer is yes, and these two new studies suggest the problem might be worse than we had feared.
In the first new study, researchers examined the placentas of new mothers and analyzed them for microplastics. They discovered that the placentas of mothers who gave birth prematurely contained significantly more microplastics than the placentas of mothers who carried their babies to full term. Levels of microplastics in the placentas of mothers who gave birth prematurely were among the highest levels ever recorded in human tissue, exceeding previous measurements of microplastics in human blood.
At present, the researchers can’t explain their findings. The result is paradoxical: you’d expect more microplastics to accrue the longer a baby is in the womb, not the other way around. But mothers who give birth prematurely accrue more in a shorter period of time. What is clear, at least, is that that there must be some mechanism within the body, or some acute source of exposure to microplastics, waiting to be discovered—a “known unknown” or “known unknowns,” to borrow a famous phrase from Donald Rumsfeld.
The second study has been making headlines in recent days, for obvious reasons. Did you know your brain could contain as much as a credit card’s worth of plastic (seven grams)?
Researchers examined brain samples taken from people who had died between 2016 and 2024 and measured them for plastic content. Other research had already shown, in humans and animals, that microplastics can cross the blood-brain barrier, which is the brain’s only protection against harmful substances and organisms, so it was reasonable to expect brain tissue to contain microplastics. The researchers found that levels of plastic in the brain samples increased by 50 percent in just eight years, and the median weight of plastic in a brain sample from 2024 was 4,917 micrograms per gram, or about five grams per kilogram. The average brain weighs roughly 1.5 kilograms, so 1.5 x 5 = 7.5 grams. The weight of a credit card.
Concentrations in brain samples are about 12 times higher than in liver or kidney samples.
Older brain samples, from the period 1997 to 2013, were obtained for comparison, and showed a steady increase in concentrations of plastic that mirrored the global increase in plastic production, as we might expect.
The researchers also found clear evidence of a link between dementia and microplastic exposure. The brains of people diagnosed with dementia contained up to 10 times more microplastic particles than the brains of those without the condition. The researchers can’t say that the extra plastic caused the dementia, but the link is highly suggestive.
Polyethylene, the most commonly produced plastic, accounted for around 75 percent of all detected plastic, suggesting that exposure derives overwhelmingly from ordinary forms of plastic goods.
Pretty scary, no? So what can be done? In the United States, at least, a golden opportunity to address the threat to health from microplastics now presents itself, with the election of Robert F. Kennedy Jr. as head of the Department of Health and Human Services.
RFK Jr. has already identified multiple issues for his “Make America Healthy Again” agenda, ranging from municipal fluoridation and the infant vaccine schedule, to toxic chemicals, processed food and regulatory corruption. We have a good idea of what and who he will be targeting.
But one thing RFK Jr. hasn’t mentioned is microplastics, although he’s obviously familiar with them. Action on microplastics would have to begin with more research, since we don’t understand nearly enough to be able to protect ourselves fully against them. RFK Jr. has said the research priorities of the National Institutes for Health must change, and I couldn’t agree more. The NIH should fund serious, determined research into microplastics to answer basic questions we still don’t know the answers to, and consider it a matter of national priority.
Questions like: What are typical levels of exposure? Is there a “safe” limit? Who is most at risk of exposure and why? What do microplastics do within the body—are there natural mechanisms that remove microplastics or sequester them within the body? What are the best ways to reduce exposure? Can we remove microplastics from our bodies? Can we produce safe alternatives to traditional plastics, since it appears that biodegradeable plastics and plastics made from plant-based materials rather than oil—often called “bioplastics”—may be just as toxic as traditional plastics?
It’s taken decades for this problem to emerge, and it will take years for it to be solved—or even for a reasonable compromise to emerge if we can’t eliminate plastics, which is a real possibility. We need to get moving before it’s too late.
