Germs More Attracted to Women's Hands

We have all heard doctors, researchers and even our parents tell us to wash our hands, but it seems even with diligent handwashing, germs still appear in abundance. Thousands of species of bacteria live on human hands and women seem to carry more bacteria than men. Women also had more of a range of bacteria on their hands than men.

A new University of Colorado at Boulder study evaluated 51 sets of hands to study the species of bacteria that were found. The study’s findings surprised researchers by the fact that not only do human hands carry much greater numbers of bacteria species than previously thought, but also that women have a significantly greater diversity of microbes on their palms than men. Of the 102 hands evaluated during the study, researcher noted that each hand averaged carrying 150 different species of bacteria. In all, researchers, led by Noah Fierer from the University of Colorado found over 4,700 bacterial species among those hands evaluated and only 5 percent of the bacteria was found to be in common among all volunteers. Even when comparing the right and left palms of the same individual there were only 17 percent shared bacteria types on average. Also, on average, women had 50 percent more species of bacteria on their palms than men.

The new study has been recently published in the Proceedings of the National Academy of Sciences. This new study found over 100 times more gene sequences than had been previously found in studies of skin-bacteria. Diverse bacteria on the palms of hands are three times higher than germs or bacteria found on the forearm and elbow, and bacteria on palms of hands even appeared to out number bacteria found in the mouth or lower intestines.

Researchers think that women may have more diverse germs on their palms not necessarily because they are not keeping up hygiene, but possibly because their hands have different acidities than men. Or it may be that they have different hand washing regimens, differences in sweat production, variations in hormones, or possibly how often cosmetics or hand lotions are applied to a woman’s hands. One thing helping men to ward off some of the germs could be their more acidic skin compared to women.

Even though the researchers stressed hand washing to still be a good practice, during the study, after hand washing, either the bacteria came back quickly or the hand washing wasn’t enough to dislodge the bacteria found on the hands, according to the researchers. Though some bacteria was reduced after hand washing there were some that were actually more abundant. Researchers said washing hands with anti-bacterial cleansers regularly was still an effective way to minimize the risk of disease because the cleansers seem to specifically target harmful bugs.

University of Colorado biochemistry assistant professor Rob Knight, a co-author of the paper, said, "The vast majority of bacteria are non-pathogenic, and some bacteria even protect against the spread of pathogens,” and "From a public health standpoint, regular hand washing has a very positive effect." Dr Valerie Curtis, director of the Hygiene Centre at the London School of Hygiene and Tropical Medicine, in regards to bacteria and germs on hands said "Most are likely to be neutral, just living there without doing any harm or good." But she added: "It is thought that having such flora on our hands is probably beneficial, because the bacteria occupy niches which are then unavailable to pathogens."

Researchers were very surprised at the number of bacteria species found on the hands evaluated during the recently published study and especially that women carried even a greater diversity of germs than men on their palms. They feel their research could potentially help to identify which species are linked to certain diseases through an establishment of a “healthy baseline” of bacteria species on the human hand.