In August, the University of California at Davis published a study showing that triclosan, a commonly used antibacterial agent, weakens skeletal and cardiac muscle in mammals, and impairs swimming in fish. The study is another blow to the besieged chemical, which has previously been knocked for messing with hormones and contributing to bacterial resistance.
Triclosan (TCS) has been with us for 40 years, an industrial bactericide found in, according to the study, “cleaning supplies, bedding, clothes, fabrics, shoes, carpets, plastics, and medical devices.” Because it builds up in the environment, though, the study says it can also be found in “raw and treated waste water, natural streams, sewage sludge, fish, and human samples of urine, plasma, and breast milk.” The recent vogue in hand sanitizers and antibacterial soaps means it's in a lot more purses and guest bathrooms, too. But as far as benefits, there's only evidence that it's good in toothpaste, for fighting gingivitis.
In the latest study, researchers found that TCS disrupts calcium channels in cells. Mice had a 25 percent reduction in cardiac activity and a nearly 20 percent reduction in grip strength. Meanwhile, fathead minnows, used to determine pollution in waterways, lost significant swimming abilities.
Bruce Hammock, a co-author of the study, says it's a matter of risk versus benefit. For people at risk for gingivitis, it's a good deal. It's handy in surgical scrubs. “But having it in every liquid soap in the nation,” says Hammock, makes it an environmental health problem. He says 99.9 percent of the TCS in the environment comes from liquid soap.
The day after the study appeared, the FDA amended its informational page on TCS to say that while there is not sufficient evidence that TCS poses a risk to humans, its effects on muscle and endocrine function in animals means the FDA is going to go ahead and take a closer look at this whole thing. That TCS may contribute to bacterial resistance explains why the FDA reminds us that there's no evidence that antibacterial soaps are any better at getting us clean that plain old soap and water.
So the research is starting to pile up against TCS. Around the time the study came out, Johnson & Johnson announced it was phasing it out of its products worldwide.
Hammock says it's a kind of cultural equation. “Once the compound has initials, it's on its way out.” Now that triclosan is familiar enough to go by TCS, Hammock says, it's just a matter of time before it follows BPA (Bisphenol-A, of baby bottle fame) out of favor, sparing us potential future health problems, and mice with weak handshakes.