A newly released study by the University of Colorado finds that hands harbor many more forms of bacteria, in far greater numbers, than previously realized and that women have a significantly higher amount of bacteria on the palms of their hands than men. These were some of the key findings reported by Noah Fierer, an assistant professor in the University of Colorado's Ecology and Evolutionary Biology Department.

"The vast amounts and different types of bacteria found on the hands of study participants were quite unexpected," Fierer says.  "Especially the greater diverseness of bacteria detected on the hands of women."

For the study, 51 college students were selected -- 102 hands total.  Researchers found an average of about 150 different types of bacteria on the hands tested.

It is uncertain why women harbored more and a wider range of bacteria on their hands.  However, Fierer suggests it may be because men generally have more acidic skin than women as well as differences in sweat and oil gland production. Additionally, women use more cosmetics, moisturizers, and other personal items on their hands and skin, which may result in greater bacteria counts.

"Proper handwashing is key to removing bacteria from hands," says Diane Mahana, marketing manager for Pro-Link, a leading jan/san marketing and buying group that has just introduced a hand hygiene program for children, Get the Germs Before They Get You.  "Even though the program is directed toward children, this study shows how important hand hygiene is for all of us."

In addition to the disparity and amount of bacteria found on the hands of men and women, the study also found that few individuals share the same types of bacteria.  This disparity went even further when the researchers reported that an individual's left hand and right hand shared only 17 percent of the same bacteria.

The report also noted that proper hand hygiene must be viewed as ongoing and that hands should be washed frequently throughout the day.  This is because bacteria can "quickly re-form after handwashing," according to the researchers.