Triclosan, an antimicrobial agent found in toys, toothpaste, cosmetics and more than 2,000 other consumer products, has been found to wreak havoc on the guts of mice whose blood concentrations of the compound are roughly equivalent to a typical level for humans.
One group of mice who were fed a diet laced with triclosan for three weeks ended up with low-grade inflammation of the colon and saw their garden of gut microbes become depleted. When researchers chemically induced inflammatory bowel disease in another group of mice, those exposed to real-world levels of triclosan suffered increased damage to the colon and more severe symptoms of colitis than did mice who weren't fed the chemical.
Finally, in mice made to develop colon cancer, those exposed to triclosan developed more and larger tumors, fueled by the activation of genes known to drive the cancer's growth. These mice also were slightly more likely to die of colon cancer than their triclosan-free counterparts. However, the difference was too small for scientists to say it was statistically significant.
The findings were published in the journal Science Translational Medicine.
The study authors, led by Haixia Yang, a postdoctoral food science researcher at the University of Massachusetts Amherst, discovered that the guts of triclosan-fed mice were particularly depleted of Bifidobacterium, a strain that has anti-inflammatory effects.
By changing the gut's microbiotic population and activating genes that govern inflammation and cancer growth, triclosan "could cause adverse effects on colonic inflammation and colon cancer," the team wrote. "Further studies are urgently needed to better characterize the effects of (triclosan) exposure on gut health to establish science-based policies for the regulation of this antimicrobial compound."
Research has demonstrated triclosan's toxicity at high doses, but this study explored the compound's safety at more typical levels of exposure.
Triclosan used to be widely used in antibacterial soaps and hand sanitizers. The Food & Drug Administration has declared it and 24 other antimicrobial compounds to be "not generally recognized as safe" and ordered it removed from soaps and hand sanitizers by the end of the year.