Ask the doctors: Teen’s drastic reaction to triclosan study worries parents

Dear Doctor: One of our teens, who is obsessed with science and medicine, says she read a story that there’s something in toothpaste that causes colon cancer. Now she’s refusing to brush her teeth. Is there any truth to what she’s read? If so, should we all stop using toothpaste?

Dear Reader: Your teen is referring to triclosan, a highly effective antimicrobial and antifungal agent. This won’t make her happy, but it’s found in more than 2,000 consumer products, including cleansers, personal care and household goods, and some pet supplies. That means it’s found in everything from toothpaste, clothing and makeup to kitchenware, furniture and toys.

In 2016, the FDA stopped manufacturers from offering for sale any over-the-counter antiseptic wash products like liquid, foam and gel hand soaps, bar soaps and body washes that contain triclosan. The ruling came as a result of studies that found the compound can alter hormone regulation in animals, could have a hand in the development of antibiotic-resistant germs and might be harmful to the immune system. So far, the FDA hasn’t stepped in to prevent the use of triclosan in toothpaste, where it is claimed to help protect against gingivitis. And for products like clothes, cookware, furniture and toys, which don’t make health claims, the regulation of triclosan is up to the Environmental Protection Agency.

The reason your teen is talking about triclosan right now is the publicity generated by the results of a recent study, which linked even short-term oral exposure to triclosan with adverse effects on the colon and its colonies of beneficial bacteria. Before we get to the details, it’s important to note that these studies were done on mice, and that further research regarding the effects of triclosan on humans is needed. However, because the mouse genome is similar to our own, with many shared genes, research in mice offers insights into certain risk factors that can extend to the human population.

Regarding this new study, mice who were fed a diet laced with triclosan over the course of three weeks wound up with inflammation of their colons. They also had a gut microbiome that was measurably depleted, particularly of Bifidobacterium, a strain that has been shown to fight inflammation. Another group of mice who had triclosan introduced into their diets and were then induced to develop inflammatory bowel disease had symptoms that were more severe, and colon damage that was more extensive, than the non-triclosan mice. Although some triclosan mice developed colon cancer with tumors that were larger and more aggressive than those of the non-triclosan mice, the researchers reported that the differences between the two groups were too small to be statistically reliable.

Because colon cancer is associated with inflammation, interest in these new triclosan studies is quite keen. We fully expect to see more research into the subject. In the meantime, no, we definitely don’t think you should stop brushing your teeth. But there are toothpastes without triclosan, and identifying them for the family seems like a great project for the young scientist in your household.