Health workers who regularly wash their hands with antibacterial soap have been found to be exposed to potentially unsafe levels of triclosan, a chemical that is currently being reviewed by the U.S. Food and Drug Administration.

Triclosan is a common ingredient that is added to certain soaps, clothing, cookware, cosmetics, furniture and toys in order to prevent bacterial contamination. However, research has shown that triclosan can alter hormone regulation in animals, and may even contribute to the development of antibiotic-resistant germs.

Researchers at UC San Francisco looked at urine samples from physicians and nurses, divided into two groups. The first group used antibacterial soap with 0.3 percent triclosan, and the second group used just soap and water.

Group one was found to have much higher levels of triclosan in their urine, compared to the second group.

Co-investigator Paul Blanc, MD, a professor of medicine at UCSF who holds the Endowed Chair in Occupational and Environmental Medicine, recommends using non-triclosan-containing soaps if they are available. Using plain soap and water can be just as effective at eliminating germs, without the negative side effects associated with additional chemicals like triclosan.

“Antimicrobial soaps can carry unknown risks, and triclosan is of particular concern. Our study shows that people absorb this chemical at work and at home, depending on the products that they use,” said Blanc in a statement.

The findings of the study are published in the Journal of Occupational and Environmental Medicine.