- Author: Kathy Keatley Garvey
The ground-breaking study, published in the Proceedings of the National Academy of Sciences, was led by NIEHS-funded scientists Robert Tukey, director of the Superfund Research Program at UC San Diego and Bruce Hammock, director of the UC Davis Superfund Research Program.
In its January newsletter, NIEHS ranked the triclosan study No. 2 in grant-funded research published in 2015. Some 2514 NIEHS-funded research papers were published in 2015. The institute, part of the National Institutes of Health, also singled out 27 other papers for special recognition.
Triclosan is a widely used antibacterial chemical found in cosmetics, soaps, shampoos, toothpastes and many other household products, said Hammock, who holds a joint appointment with the UC Davis Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center. “This study, using laboratory mice, raises concerns about the safety of triclosan in humans,” he said. These findings add to earlier reports triclosan can disrupt hormones and impair muscle contraction.
The paper, “The Commonly Used Antimicrobial Additive Triclosan is a Liver Tumor Promoter,” drew widespread attention from news media, scientists and consumers.
The team also chemically induced liver tumors in the mice and found that the mice exposed to triclosan showed a large increase in tumor multiplicity, size, and incidence compared to unexposed mice.
Hammock said the findings suggest 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.
Other co-authors of the paper are Mei-Fei Yueh, Koji Taniguchi, Shujuan Chen, R. M. Evans and Michael Karin, all of UC San Diego; and Ronald M. Evans, Salk Institute for Biological Studies.
Hammock was featured in the January 2015 edition of Chemical Research in Toxicology, and in the Sept. 4, 2014 edition of Newsweek in a piece titled "Is Cancer Lurking in Your Toothpaste? (And Your Soap? And Your Lipstick? Hammock called triclosan “quite a good antimicrobial” that belongs in the hospital, not on the kitchen counter, and told reporter Alexander Nazaryan, “There's no reason for it to be there" (in hand and dish soaps).
The research was funded, in part, by U.S. Public Health Service grants ES010337, GM086713, GM100481, A1043477, ES002710 and ES004699.