An ingredient in antibacterial soaps, toothpaste, and other common household items promoted liver tumor growth in mice, according to a new study.  The chemical in question is Triclosan, the same stuff that earlier research linked to disrupted hormonal development, a reduction in bacterial resistance, and an increase in allergies.

“It’s not a direct carcinogen,” said the study’s author Robert Tukey, a professor of chemistry, biochemistry and pharmacology at the University of California San Diego School of Medicine.  “It’s a tumor promoter.”

The research showed that mice that were exposed to Triclosan had more tumors, bigger tumors and more frequent tumors than mice that were not exposed to it.  The chemical also apparently interferes in the way the liver cleanses the body of foreign chemicals.  To compensate for this stress, liver cells proliferate and turn fibrotic over time, causing cirrhosis.

Many doctors recommend using regular soaps and thorough hand washing techniques, since the detergent in regular soap is enough to deal with germs.  Dr. Tukey says he won’t use products containing Triclosan.

“We don't see a little bit of tumors,” Tukey said.  “We see very full blown tumorigenesis.  It’s on the extreme end of a tumor promoter and it does it very rapidly.”