Could microplastics be causing the increase in bowel cancer?
Two of New Zealand’s leading cancer researchers are seeking more funding to investigate a potential link between microplastics and a rise in bowel cancer in people under 50.
There has been a near 80% increase in the number of under 50s being diagnosed with cancer globally in the last three decades.
Of particular concern for that age group is the increase in colorectal (bowel) cancer – rising 26% per decade.
For Māori in particular, it was rising 36% per decade, colorectal surgeon and professor at the University of Otago, Christchurch, Dr Frank Frizelle, said.
Despite the increases, National’s campaign promise to lower the bowel screening age to 45 has yet to be implemented.
Health Minister Shane Reti told The Post yesterday he was “receiving briefings” on the matter and was “uncertain” of a time frame.
The delay was “very disappointing”, Frizelle said.
Over 3300 Kiwis are diagnosed with bowel cancer each year, including about 350 people under 50.
The speed and size of the increase in younger people has led experts to believe it is a result of changes in the environment.
University of Canterbury toxicology professor Ian Shaw said more research was needed, but there appeared to be a link between microplastics (fragments of any type of plastic less than 5mm in length) and colorectal cancer.
While nothing had been proven yet, the microplastics a person ingested could get stuck in the intestines, disrupting the mucus layer in the gut and reducing its protective effect – increasing the likelihood of colorectal cancer, Frizelle said.
Microplastics were not particularly toxic themselves, but could “damage things ... and allow things, like bacteria, to travel with them through the mucus layer”.
“It’s like sticking an arrow through the two mucus layers.”
Microplastics may play a role in both the initial formation of a cancer cell and helping it grow into a tumour.
Putting substances into human or animal tissue could cause an inflammatory response that could cause cells to divide. The more often a cell divides, the greater the risk of a cancer cell forming.
Putting microplastics into tissue would set up the inflammatory response, Shaw said.
“It’s also possible microplastics might deliver carcinogens – like a bus taking them to cells in the body.”
Both Frizelle and Shaw said more research was needed to prove the connection, but they needed more funding to do that.
“We can’t prove they are connected but we know they [microplastics] are there and we know they have got a way to initiate and promote a tumour so we need to look at that in more detail,” Shaw said.
Microplastics are everywhere. Reducing your use of plastics is the obvious answer, but without knowing the risks it was hard to say.
“You can’t stop eating, you can’t totally avoid eating foods with microplastics because they are everywhere. So the only way you can stem the problem is stopping the production of microplastics and that’s going to be a very long, slow process and they’re going to be there for a very long time,” Shaw said.
It was difficult to say what foods might contain microplastics, but the more obvious culprits (in theory) were mussels and filter feeding marine creatures, he said. Microplastics were also found in clothes.
Recent studies found microplastics in some plants and therefore in some vegetables, Shaw said.
It was important to weigh up the risks versus benefits.
“The risk of the microplastics we can’t assess, but the benefits of the food is very great. We don't know if it’s possible to avoid certain foods to avoid an unknown risk of microplastics.”