If co-workers and family members are coming down with infections this winter, you may be tempted to turn to an anti-bacterial soap for protection.
But some scientists are increasingly concerned that a common anti-bacterial ingredient called triclosan may harm people's health. Laboratory studies have found that it may disrupt hormones, interfere with muscle function and promote the growth of stronger bacteria — and other research suggests it is building up in the environment to the possible peril of wildlife.
What's more, there is no evidence that hand-washing with soap containing triclosan or other anti-microbial ingredients offers any health advantages over regular soap and water, according to advisory committees for the American Medical Association and the U.S. Food and Drug Administration.
"Triclosan is what we call a stupid use of a chemical," said Dr. Sarah Janssen, a physician and senior scientist with the Natural Resources Defense Council, an environmental advocacy group. "It doesn't work, it's not safe and it is not being regulated."
The nation's main trade association for soap manufacturers, the American Cleaning Institute, says triclosan is effective against certain infectious bacteria and the health concerns are overblown.
Yet the FDA, which oversees the use of chemicals in food and drugs, has never completed a safety review and issued binding usage rules for triclosan. For nearly 40 years, manufacturers have been free to make and market products using the chemical even as evidence of potential health and environmental problems mounted.
Spurred by research results as well as lawsuits and petitions, the FDA in 2010 agreed to take another look at triclosan. The U.S. Environmental Protection Agency, which regulates the chemical's use as a preservative and pesticide, also moved up a comprehensive re-evaluation to 2013, a decade ahead of schedule.
The FDA promised to publish a review based on recent science by spring 2011. After missing that deadline, the agency set winter 2012 as the next target. The agency now says it does not have a new target date, frustrating health and safety advocates.
"We want to get it right before we put something out there, and we haven't been able to do that yet," said Doug Throckmorton, who is coordinating the review for the FDA.
Originally created for use in health care settings, triclosan (and triclocarban, used in solid soaps) has been added to dozens of consumer products, including body wash, toothpaste, deodorant, toys, clothing and yoga mats. Currently the only triclosan benefit recognized by the FDA is its ability to prevent gingivitis when added to toothpastes.
Allison Aiello, an associate professor of epidemiology at the University of Michigan, conducted a review of available scientific literature and concluded in a 2007 report that soaps containing triclosan "were no more effective than plain soap at preventing infectious illness symptoms and reducing bacterial levels on the hands."
Hand-washing, she notes, works largely by dislodging and rinsing away bacteria and viruses on the skin rather than killing them.
Soap industry spokesman Brian Sansoni, however, cites other research indicating that triclosan-treated soaps "are safe and effective, and they do what they say they do."
"They kill germs that make us sick," he said. "It has been one of the most researched and reviewed ingredients in consumer and health care products over the past 40 years."
For example, one review published in 2011 found that anti-microbial soap had a small advantage over regular soap in terms of microbes left on the skin. The benefit was strongest when hands carried higher bacterial loads.
The author, Rutgers University food science professor Donald Schaffner, said examples would include instances when a person's hands were contaminated with "vomit or feces or they had been handling ground beef or raw chicken."
Schaffner acknowledged that the American Cleaning Institute both funded and helped shape the scope of the research but said he stood behind the findings.
Aiello questioned whether the benefits found in that study were relevant to everyday hand-washing and said other research promoted by the soap industry lacked rigor and relied on small sample sizes.
Whether or not triclosan makes hand-washing more effective, Aiello and other scientists fear that frequent use will cause bacteria to develop an increased tolerance to the chemical, decreasing its effectiveness in settings where it is truly needed, such as in hospitals.
Though laboratory studies have demonstrated that exposure to triclosan can allow more tolerant bacteria to multiply, it remains unclear whether everyday use would increase bacterial resistance.