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Microplastics, tiny fragments of plastic measuring less than five millimetres, have now been discovered not only in human blood and organs, but deep within bones and even the brain. Recent studies from the UK, China, Italy, and the US reveal just how far plastic pollution has infiltrated the human body, raising urgent questions about its long-term health consequences.
The evidence was unearthed through both historical and cutting-edge scientific investigations. At Rothamsted Research in Hertfordshire, England, home to the world’s longest-running agricultural experiments, century-old soil samples have revealed the creeping rise of plastic contamination. Andy Macdonald, known by colleagues as the “Keeper of the Bottles,” oversees this archive and notes that microplastics began appearing in soil samples around the 1920s, with a sharp increase from the 1960s onward.
“We can clearly see the pre- and post-plastic eras in our samples,” Macdonald explained. “Microplastics likely entered the soil from everything from atmospheric fallout to tire debris from tractors.”
Fast-forward to 2025, and the plastic problem is no longer confined to the environment; it’s inside us. A groundbreaking human challenge trial in London earlier this year saw volunteers drink fluids prepared using plastic containers and teabags, mimicking everyday behaviour. Led by Dr. Stephanie Wright of Imperial College London, the study aimed to track the absorption of microplastics in the body.
“We know that heat and plastic are a dangerous mix,” said Wright. “We’re testing just how much of this plastic ends up in the bloodstream after common household use.”
Early data suggest that microplastics can cross the gut barrier into the blood, with smaller particles, known as nanoplastics, posing even greater risks as they may penetrate cells and organs. These particles have now been found in the liver, spleen, lungs, kidneys, and even the carotid arteries, which supply blood to the brain.
A 2024 study by Italian researchers revealed that people with early-stage cardiovascular disease who had microplastics in their artery plaques were 4.5 times more likely to suffer strokes, heart attacks, or sudden death over the next three years.
Another startling discovery came in early 2025 when scientists identified high concentrations of microplastics in the brains of cadavers, especially in those who had suffered from dementia. “We were shocked,” said Dr. Matthew Campen, a toxicology professor at the University of New Mexico. “Patients with dementia had up to ten times the level of microplastics compared to others.”
Campen believes the brain’s high fat content and impaired blood-brain barrier in dementia may facilitate the buildup of plastics. “It’s a perfect storm, our most vulnerable organ being exposed to something our body can’t break down.”
While researchers are cautious not to claim microplastics as a sole cause of diseases like dementia or heart conditions, many believe these particles act as silent stressors, intensifying chronic inflammation, oxidative stress, and potentially accelerating ageing.
Professor Fay Couceiro from the University of Portsmouth sums it up: “They’re not asbestos. They’re not an immediate threat. But they are a slow, insidious burden on the body, pushing it closer to disease.”
The complexity of the issue is magnified by the fact that “microplastics” is an umbrella term covering thousands of plastic types, shapes, and chemical compositions. A single bottle of water can contain up to 240,000 plastic particles of varying materials.
“Some plastics absorb toxins or carry heavy metals,” explains Verena Pichler, pharmaceutical chemist at the University of Vienna. “Others may disrupt hormones or immune responses. The variability is enormous.”
Despite the unsettling discoveries, researchers stress the importance of continued study rather than panic. More human data is needed to understand the true extent of health risks and guide global regulation.
Looking ahead, efforts are mounting to reduce exposure, ban harmful plastic additives, and develop safer materials. But for now, the burden of plastic on human health has become too big and too embedded to ignore.
“We’re all part of an uncontrolled global experiment,” says Dr. Wright. “And it’s time we start asking what price we’re paying for our plastic dependence.”
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