Bruce Hammock, Ph.D.; Michael Karin, Ph.D.; Robert Tukey, Ph.D.
University of California, Davis; University of California, San Diego
NIEHS Grants R01ES002710, P42ES004699, P42ES010337
NIEHS grantees report that mice with long-term exposure to the antibacterial agent triclosan experienced fibrosis and acceleration of cancer development in the liver. These findings add to earlier reports that this widely used antimicrobial agent can disrupt hormones and impair muscle contraction.
The researchers exposed mice to triclosan for six months, which equates to about 18 human years. The triclosan-treated mice exhibited cell proliferation, liver fibrosis, and proinflammatory responses that together form the type of environment within which human liver cancer forms. The researchers also chemically induced liver tumors in the mice and found that the mice exposed to triclosan had a large increase in tumor multiplicity, size, and incidence compared to unexposed mice. Findings from the study suggests that triclosan’s negative effects on the liver may result from interference with the constitutive androstane receptor, which plays a role in clearing foreign chemicals from the body.
The authors recommend that because the findings strongly suggest there are adverse health effects in mice with long-term exposure, the relevance of triclosan liver toxicity to humans should be evaluated. They also pointed out that eliminating the use of triclosan in products that are high volume but low benefit, such as hand soaps, would help lessen exposure.
Citation: Yueh MF, Taniguchi K, Chen S, Evans RM, Hammock BD, Karin M, Tukey RH. 2014. The commonly used antimicrobial additive triclosan is a liver tumor promoter. Proc Natl Acad Sci U S A 111(48):17200-17205.