The Dirty Little Secret of Liquid Soap

Your liquid soap could be toxic.

A common ingredient found in liquid soap, as well as some shampoos, toothpaste and other personal hygiene products, is a chemical named triclosan.

Despite the fact that it is so widely used, this antimicrobial could pose potentially serious consequences after long-term exposure.

Specifically, triclosan causes liver fibrosis and cancer in laboratory mice through molecular mechanisms that are also relevant in humans, according to researchers from the University of California, San Diego and the University of California, Davis.

Lead study author Dr. Robert H. Tukey warns that the broad use of triclosan presents "a very real risk of liver toxicity for people, as it does in mice."

The mice that were exposed to triclosan for six months, which is roughly the equivalent to 18 human years, were more susceptible to chemically-induced liver tumors. Their tumors were also larger and more frequent than in mice not exposed to triclosan.

How does triclosan damage the body? The chemical appears to interfere with the constitutive androstane receptor, a protein responsible for detoxifying (or clearing away) foreign chemicals in the body. To compensate for this stress, liver cells proliferate and turn fibrotic over time. Repeated triclosan exposure and continued liver fibrosis eventually promote tumor formation.

Triclosan is perhaps the most ubiquitous consumer antibacterial. Studies have found traces in 97 percent of breast milk samples from lactating women and in the urine of nearly 75 percent of people tested. Triclosan is also common in the environment: It is one of the seven most frequently detected compounds in streams across the United States.

"We could reduce most human and environmental exposures by eliminating uses of triclosan that are high volume, but of low benefit, such as inclusion in liquid hand soaps," Hammock said. "Yet we could also for now retain uses shown to have health value--as in toothpaste, where the amount used is small."

Triclosan is currently under scrutiny by the FDA, thanks to its widespread use and recent reports that it can disrupt hormones and impair muscle contraction.

The study findings were published in the Proceedings of the National Academy of Sciences.

--From the Editors at Netscape

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