Soap power: Handwash chemical linked to cancer

Reuters / Mariana Bazo
Washing your hands with antibacterial soap may be dangerous, a new US study reveals. A chemical found in many liquid handwashes and other basic household products like shampoos and toothpaste has been linked to cancer.

Triclosan is an antimicrobial agent of broad-spectrum and one of the most common additives used in a wide range of consumer products, from kitchenware to toys. Studies have also found traces of the chemical in 97 percent of breast milk samples from lactating women and in the urine of nearly three-quarters of people tested. Triclosan is also common in the environment, being one of the seven most-frequently detected compounds in streams across the US.


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Researchers from the University of California, San Diego School of Medicine, have found that triclosan causes liver fibrosis and cancer in laboratory mice through molecular mechanisms that are also relevant in humans.

"Triclosan's increasing detection in environmental samples and its increasingly broad use in consumer products may overcome its moderate benefit and present a very real risk of liver toxicity for people, as it does in mice, particularly when combined with other compounds with similar action,"
study leader Professor Robert H. Tukey stated in a press release. The full study has been published in the Proceedings of the National Academy of Sciences on Monday.

Tukey found that triclosan disrupted liver integrity, compromising liver function in mouse models. Mice exposed to the chemical for six months (roughly said to be equivalent to 18 human years) were more susceptible to chemical-induced liver tumors. Their tumors also proved to be larger and more frequent than in mice not exposed to triclosan.

The researchers say triclosan may cause harm when interfering with a protein responsible for detoxifying foreign chemicals in the body, the so called constitutive androstane receptor. As a result, liver cells proliferate and turn fibrotic. In the long run, continued liver fibrosis boosts tumor formation.



Triclosan is under scrutiny by the US Food and Drug Administration (FDA). The agency stated on its website that while it currently doesn't have evidence that triclosan added to antibacterial soaps and body washes provides extra health benefits over soap and water, "consumers concerned about using hand and body soaps with triclosan should wash with regular soap and water."

The US scientists also recommend avoiding products that contain triclosan, except for toothpastes where the amount used is small.

"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,"
one of the researchers, Professor Bruce D. Hammock of the University of California said.