According to a research published in the May issue of the journal of Applied and Environmental Microbiology, they can be. The study, conducted by GOJO Industries, shows that soap dispensers with sealed, disposable containers are preferable to the normal refillable ones, as these refillable containers can become contaminated with Gram-negative bacteria. In fact during the study, 14 contaminated soap dispensers were found at an elementary school in Arizona, and the volunteers, or as they are better known, the Guinea Pigs, were found to have MORE bacteria on their washed hands, than they had previously to washing with the contaminated soap.
Furthermore, the study also showed that these bacteria can be directly redistributed by hand contact onto other surfaces like door handles and ATM keypads.
But as one of the volunteers put it; ‘ At least my hands smell good now…’
After the study was concluded, the school’s contaminated soap dispensers were replaced with dispensers using sealed-soap refills. After one year, not one of them was found to be contaminated.
