Triclosan is an antimicrobial commonly found in soaps, shampoos and other household items. As a consequence of its use in many consumer products, it is frequently detected in water samples, and studies have also found traces in human bodily fluids like breast milk and urine.

Robert H. Tukey, University of California, San Diego, La Jolla, USA, Bruce D. Hammock, University of California Davis Cancer Center, USA, and colleagues have studied the consequences of long-term exposure to triclosan. In a feeding study, they exposed mice to the antibacterial for six months. It was found that triclosan can stimulate liver cell proliferation as a stress response. This leads to liver fibrosis, compromises liver function, and promotes the growth of liver cancer induced by diethylnitrosamine.

This study gives strong evidence for adverse health effects of triclosan in mice, and leads the researchers to the conclusion that the toxic effects of triclosan on humans should be investigated more closely.

• The commonly used antimicrobial additive triclosan is a liver tumor promoter,
  Mei-Fei Yueh, Koji Taniguchi, Shujuan Chen, Ronald M. Evans, Bruce D. Hammock Michael Karin, Robert H. Tukey,
  Proc. Natl. Acad. Sci. U. S. A. 2014.
  DOI: 10.1073/pnas.1419119111