A study in mBio® this week points to yet another reason to potentially be cautious about the man-made antimicrobial compound triclosan. The agent, commonly found in household soaps, shampoos, toothpastes, medical equipment and other materials, may be finding its way inside human noses, where it can promote the colonization of Staphylococcus aureus bacteria and predispose some people to infection.
The study, from researchers at the University of Michigan, found traces of triclosan in the nasal passages of 41 percent (37 of 90) of healthy adults studied. Among those with traces of triclosan, 64 percent also were colonized with S. aureus. By contrast, only 30 percent of adults without triclosan had S. aureus colonization.
Additional experiments found that S. aureus grown in the presence of triclosan was better able to attach to human proteins, and that rats exposed to triclosan were more susceptible to S. aureus nasal colonization.
Triclosan is “really common in hand soaps, toothpastes and mouthwashes but there’s no evidence it does a better job than regular soap,” says senior study author Blaise Boles, PhD, an assistant professor of molecular, cellular and developmental biology at the university. “This agent may have unintended consequences in our bodies. It could promote S. aureus nasal colonization, putting some people, like those undergoing surgery, at increased risk for infection.”
While triclosan has been around for 40 years, it has been incorporated into many household products within the past decade, says Boles. His is not the first study to note its spread to humans: Other studies have found traces of triclosan in human fluids including serum, urine and milk, and studies in mammals have found that high concentrations of triclosan can disrupt the endocrine system and decrease heart and skeletal muscle function.
“In light of the significant use of triclosan in consumer products and its widespread environmental contamination, our data combined with previous studies showing impacts of triclosan on the endocrine system and muscle function suggest that a reevaluation of triclosan in consumer products is urgently needed,” Boles and colleagues wrote.
With consumer backlash and concerns from the scientific community about triclosan leading to bacterial resistance, triclosan has been banned in Europe and Canada, Boles says. In the U.S., Minnesota could become the first state to ban the agent: the Minneapolis City Council has urged the state to ban triclosan, and Gov. Mark Dayton ordered state agencies to stop using products containing the compound. In addition, the Food and Drug Administration in December issued a rule requiring manufacturers to provide more substantial data to demonstrate the safety and effectiveness of antibacterial soaps. Companies including Johnson & Johnson and Procter & Gamble have announced they are phasing out the use of triclosan in their products.
For now, Boles, who says he would like to conduct a more broad survey to determine if triclosan influences microbial colonization in additional human body sites, opts not to use products containing triclosan. But surveying products for the chemical is tricky, he notes, as triclosan also is marketed under other names including BioFresh, Microban, Lexol 300, Ster-Zac, Cloxifenolum, and Irgasan DP-300.