Concerns about Triclosan
Triclosan, a common antimicrobial in toothpaste and other products, has been linked to inflammation and cancer in the gut, reports Haixia Yang, postdoctoral researcher in food science at the University of Massachusetts Amherst.
THOUSANDS of products we use daily, such as hand soaps, toothpastes, body wash, kitchenware and toys, contain the antimicrobial chemical triclosan. Research in the US suggests it may have widespread health risks, including aggravating inflammation in the gut and promoting the development of colon cancer, prompting a call for health authorities to reassess regulation of triclosan for its effect on human health.
THE antimicrobial chemical triclosan is in thousands of products we use daily — hand soaps, toothpastes, body wash, kitchenware and even some toys. Work in our lab suggests this compound may have widespread health risks, including aggravating inflammation in the gut and promoting the development of colon cancer by altering the gut microbiota, the community of microbes found in our intestines.
Our results, as far as we know, are the first to demonstrate triclosan can promote colonic inflammation and associated colon cancer in mice. This study suggests health authorities must reassess regulation of triclosan for its effect on human health. That is key because it is impossible to avoid contact with this chemical.
Triclosan is one of the most widely used antimicrobials and is incorporated in more than 2000 consumer products. Millions of pounds of the chemical are used in the United States each year. The National Health and Nutrition Examination Survey showed triclosan was detected in about 75% of the urine samples of individuals tested in the US and it is among the top 10 pollutants found in US rivers.
Our lab at the University of Massachusetts Amherst collaborated with scientists from 13 universities to explore the effects of triclosan on inflammation in the colon. We first tested triclosan in normal, healthy mice and found the chemical caused lowgrade inflammation.
In our next round of experiments we induced gut inflammation in mice using chemicals and then fed them food containing a low dose of triclosan for three weeks. We also did the same thing with mice that were genetically engineered to spontaneously develop inflammatory bowel disease, and with mice in which we chemically induced colon cancer.
After feeding the mice triclosan at concentrations reported in human blood plasma, the colon inflammation in the mice worsened. The chemical also accelerated the development of colitis — inflammation that leads to rectal bleeding, diarrhoea, abdominal pain, abdominal spasms in humans — and the growth of tumours. In one group of mice, it reduced their lifespan.
We also wanted to know how exactly triclosan was causing harm. Because it is a bacteriakilling compound, we thought it might be disrupting the community of microbes in our guts, which is vital for maintaining good health. The mice that suffered inflammation from triclosan exposure had a lower species diversity of microbes in the gut and lower populations of the socalled “good” bacteria,
Bifidobacterium.
Our team and researchers from the University of WisconsinMadison used germfree mice – which have absolutely no bacteria in their gut – and found feeding triclosan to these animals had no effect. This finding suggests the harmful effects of triclosan are due to changes in the microbiome.
In addition, we found a protein called the Tolllike receptor 4, an important mediator of communication between the microbes and the host’s immune system, is critical for the harmful effect of triclosan. Mice that lacked this protein seemed immune to the biological effects of triclosan.
Little is known about the impact of this chemical on human health or other species. Our study indicates there is an urgent need for further evaluation and to update regulatory policies. — theconversation.com