ScienceBlog -- People who wash their hands with contaminated soap from bulk-soap-refillable dispensers can increase the number of disease-causing microbes on their hands and may play a role in transmission of bacteria in public settings according to research published in the May issue of the journal Applied and Environmental Microbiology. “Hand washing with soap and water is a universally accepted practice for reducing the transmission of potentially pathogenic microorganisms. However, liquid soap can become contaminated with bacteria and poses a recognized health risk in health care settings,” says Carrie Zapka from GOJO Industries in Akron Ohio, the lead researcher on the study that also included scientists from BioScience Laboratories in Bozeman, Montana and the University of Arizona, Tucson.