Many times you don't think about the harmful effects of a habit but some can open you up to all kinds of germs.

Think about everything you touch in a day from handles to toilets to railings.

If you bite your fingernails, that's exactly what you're putting in your mouth.

A microbiology class at Troy University Dothan took samples of a number of things people touch and the results might surprise you.

Belisle, a student in the class found a number of things on a sanitized surface in a kitchen; one place you would expect to be clean. “There was a dozen different bacteria; a couple fungi; two of them I know are staphylococcus," he said.

"There are about 100 micro organisms that can live under your fingernails and that's viruses and germs so anything that you touch with your hands you are putting in your mouth," says Wendy Knight, an infection control practitioner at the Southeast Alabama Medical Center, "You can develop staff infections; you can get some really bad gig bugs that would involve nausea, vomiting and diarrhea. You wouldn't think just simply biting your nails could make you this sick."

Microbiology professor Dr. Gary Manfready says he worries more about bacteria getting in your skin than in your mouth.

"Your body's got a great immune system and a series of ways of kicking things out,” says Manfready, "Once it gets under the epidermal layer it gets into an anaerobic environment where it's just laying around and the aerobic environment under the nail is one thing but once it gets in an anaerobic environment it just goes to town and starts growing."

When you bite far enough to open sores, you could be inviting bacteria in.

"They bite all the way up the nail bed itself so your body's more exposed to germs," says Evonne Bennett, a cosmetology and nail instructor at Wallace Community College.

So how do you quit? You can try getting acrylic nails or painting them.

“At least they have to work through the polish for a moment,” says Bennett.

She also suggests buying a polish with a bitter taste specially designed to help you stop.