A new study reinforces the wisdom of hand washing.
Researchers studying bacteria found on the human hand say they discovered many more types than they had expected to find. And, they've also found that women have a greater variety on their hands than men do.
One of the study's authors says he was astonished by "the variability between individuals, and also between hands on the same individual."
The researchers aren't sure why women had a greater variety of bacteria than men, but one suggests it may have to so with the acidity of the skin. Men generally have more acidic skin than women.
They say other possibilities include differences in sweat and oil gland production, the frequency of moisturizer or cosmetics applications, skin thickness or hormone production.
Still, the researchers say it's nothing to panic about, stressing "the vast majority of the bacteria" on the human body "are either harmless or beneficial."