antimicrobial soap
Triclosan, an ingredient common in antibacterial soaps, cosmetics, deodorants, toothpastes and more, has been under the microscope for the past few years amid growing concerns that it can disrupt key hormones that regulate growth and reproduction as well as contribute to the spread of antibiotic-resistant strains of bacteria.

Now, a new study has added another possible black mark against the chemical, showing it causes liver cancer in mice.

The study adds to a growing body of evidence that the chemical's possible harmful effects may outweigh its benefits - key information as the Food and Drug Administration weighs a possible ban on the chemical.

Robert H. Tukey, PhD, professor in the departments of Chemistry and Biochemistry and Pharmacology, led the study, which found that triclosan disrupted liver integrity and compromised liver function in mice. Perhaps most troubling, when mice were exposed to triclosan for six months (roughly equivalent to 18 human years) they were more susceptible to chemical-induced liver tumors. Their tumors were also larger and more frequent than in mice not exposed to triclosan.

The researchers explain that triclosan interferes with a protein in the body that helps clear away foreign chemicals. In reaction to this interference, liver cells proliferate and can start to form tumors.

Triclosan was initially developed as a surgical scrub for medical professionals and was first registered as a pesticide in 1969 but has since been added to a host of consumer products from kitchen cutting boards to soaps, even clothes to cut down on bacteria and odors. By 2001, 76 percent of liquid hand soaps contained the chemical.

More recent research, however, has cast doubt on its effectiveness at killing germs, In fact, in 2005, the FDA found no evidence that antibacterial washes containing triclosan were any better than washing with plain soap and water.

The chemical has become widespread - studies have found traces of it in 97 percent of breast milk samples from lactating women and in the urine of nearly 75 percent of people tested. It has also entered the environment, showing up as one of the seven most frequently detected compounds in streams sampled across the United States.

This latest study, linking the chemical to liver cancer in mice will likely contribute to the FDA's decision-making process, with a decision expected by 2015.