A new study has revealed that a common antibacterial chemical added to bath soaps can change hormonal activity in rats and in human cells in the laboratory, and does so by a formerly unreported mechanism.
The study, by the University of California - Davis researchers, comes as a growing number of studies, of both lab animals and humans, have revealed that some synthetic chemicals in household products can lead to health problems by interfering with normal hormone action.
Called endocrine disruptors, or endocrine disrupting substances (EDS), such chemicals have been linked in animal studies to a range of problems, including cancer, reproductive failure and developmental anomalies.
The current study is the first to examine the hormone effects of the antibacterial compound triclocarban (also known as TCC or 3,4,4'-trichlorocarbanilide), which is widely used in household and personal care products including bar soaps, body washes, cleansing lotions, wipes and detergents.
After conducting tests, the researchers found two key effects.
In human cells in the laboratory, triclocarban increased gene expression that is normally regulated by testosterone. And when male rats were fed triclocarban, testosterone-dependent organs such as the prostate gland grew abnormally large.
Furthermore, the authors said their discovery that triclocarban increased hormone effects was new.
All previous studies of endocrine disruptors had found that they generally act by blocking or decreasing hormone effects.
Lead author Bill Lasley said that consumers should not take this study as guidance on whether to use triclocarban-containing products.
"Our mothers taught us to wash our hands well before the advent of antimicrobial soaps, and that practice alone prevents the spread of disease," he said.
The new study was published online this week by the journal Endocrinology.