Microscopic pieces of plastic in the air we breathe and the food we eat could be causing an epidemic of colon cancer in America, new research suggests.
The number of colon cancer diagnoses has increased dramatically in the US over the past two decades, with fit, otherwise healthy people in their 20s and 30s increasingly affected by the disease.
Obesity, ultra-processed foods and taking antibiotics have all been blamed, but scientists are rushing to find a definitive cause.
Now a comprehensive review of more than 3,000 studies suggests that tiny particles smaller than a grain of rice may be the cause.
The researchers from the University of California San Francisco (UCSF) said these penetrating particles can build up in organs over time, causing irreversible DNA damage.
This leads to chronic inflammation that kills healthy cells and causes cancer cells to grow uncontrollably.
The researchers are now urging lawmakers to ‘take immediate action’ to limit future exposure to microplastics.
Researchers in California suggested that microplastics, found in everything from single-use plastics to seafood, could be responsible for the US colon cancer epidemic.
The above graph shows the increase in colorectal cancer cases in the US in men and women between 2000 and 2021.
Your browser does not support iframes.
Dr. Tracey J Woodruff, professor of obstetrics, gynecology and reproductive sciences at UCSF, said: “These microplastics are essentially particulate air pollution, and we know that this type of air pollution is harmful.”
Colon cancer is one of the fastest growing cancers, especially in Americans under the age of 50. These cases are considered early-onset.
The number of cases is expected to increase by 90 percent between 2010 and 2030 among people aged 20 to 34.
The review, published Wednesday in the journal Environmental Science & Technology, looked at 3,000 studies conducted between 2018 and 2024.
The team said that although most of the research cited was conducted in animals, the conclusions would likely apply to humans as well, because humans and animals experience the same exposure.
The researchers also pointed to several studies suggesting that exposure to microplastics could increase the risks of structural changes in the colon.
A 2022 study of mice in China, for example, found that mice chronically exposed to microplastics had “remarkable intestinal disorders,” such as damage to the walls of the colon.
Another one study published the same year suggested that exposure to microplastic caused the colon to produce less mucus, which forms a protective layer around the colon.
The Environmental Working Group, an activist organization focused on environmental pollutants, has mapped the communities and military sites confirmed to be contaminated with PFAS. Like microplastics, PFAS are found virtually everywhere in the environment
Your browser does not support iframes.
If the colon cannot produce mucus, the intestinal walls cannot protect against contaminants such as microplastics and bacteria.
Mucus also lubricates the colon and allows stool to pass easily. When stool builds up in the colon, it irritates the colon and inflames the inner lining.
This inflammation has been shown to kill healthy cells and promote the formation of cancer cells, while also inhibiting the immune system’s ability to fight back.
The researchers wrote: ‘We concluded that exposure to microplastics is ‘suspected’ to negatively impact the colon and small intestine in humans.’
They also suggested that inhaling microplastics could increase the risk of tissue damage in the lungs and cause chronic inflammation.
Microplastics are ubiquitous in the environment, circulating through the air and leaching into the human body through contact with contaminated food, water and soil.
They can also enter the bloodstream through synthetic clothing and cleaning products.
They are most commonly found in plastic bottles and containers, cosmetics, cleaning products and foods that come from oceans, such as seafood.
Raquel (left) was just 28 when doctors diagnosed her with stage four colon cancer. Evan White (right), from Dallas, was diagnosed with colon cancer at age 24. He died four years later, just weeks before his wedding
Experts recommend reducing the use of single-use plastics, filtering water and avoiding clothing with synthetic fibers to reduce exposure.
Earlier this year, researchers in Brazil found microplastics in human brains for the first time, suggesting they enter through the nose.
And research published in 2022 found microplastics in the blood of eight in 10 study participants.
There were several limitations to the new research, the most important of which was the authors’ reliance on animal studies.
The team said that ‘it is likely that our conclusions underestimate the true health consequences of microplastic exposure.
‘Importantly, these limitations highlight that there are clear opportunities for future research.’
The researchers are urging lawmakers in California and other states to impose restrictions on the use of microplastics.
Dr. Nicholas Chartres, lead author of the study and senior research fellow at the University of Sydney, said: ‘We urge regulators and policy leaders to consider the growing evidence of health harm from microplastics, including bowel and lung cancer.
“We hope state leaders will take immediate action to prevent further exposures.”