Soap additive may cause cancer, liver disease

Long-term exposure to triclosan, an ingredient found in soaps, shampoos, toothpastes and many other household items may cause liver fibrosis and cancer, a new study has warned.
Despite the widespread use of Triclosan, researchers at the University of California, San Diego School of Medicine report potentially serious consequences of long-term exposure to the chemical.
The study shows 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," said Robert H Tukey, professor in the departments of Chemistry and Biochemistry and Pharmacology.

Researchers found that triclosan disrupted liver integrity and compromised liver function in mouse models.
Mice exposed to triclosan for six months (roughly equivalent to 18 human years) were more susceptible to chemical-induced liver tumours. Their tumours were also larger and more frequent than in mice not exposed to triclosan.

The study suggests triclosan may do its damage by interfering with the constitutive androstane receptor, a protein responsible for detoxifying (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 tumour formation.

Triclosan is perhaps the most ubiquitous consumer antibacterial. Studies have found traces in 97 per cent of breast milk samples from lactating women and in the urine of nearly 75 per cent of people tested.
Triclosan is also common in the environment: It is one of the seven most frequently detected compounds in streams across the US, researchers said.
"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," Hammock added.

The study was published in the journal PNAS.