Aug. 4, 2006  -- We've seen George Bush chat away on a cell phone, not to mention Paris Hilton. And don't forget Maxwell Smart, the secret agent who used his shoe for a phone.

Believe it or not, his shoe phone could have been cleaner than your cell phone.

When people in New York City were asked which they thought was dirtier -- the sole of your shoe, a toilet seat or a cell phone -- the answer was overwhelmingly the toilet seat.

But they were wrong -- your cell phone is filthier.

New research out of the United Kingdom found mobile phones are a technological petri dish for tens of thousands of germs.

Why? Germs multiply in warm places. Between the heat the phones generate and the germs on faces and hands, you've got a bacterial breeding ground.

"You put it in a warm place, you hold it in your hand, you put it in your pocket like I do, it's nice and warm," said microbiologist Chuck Gerba. "Bacteria like that. It can grow in these types of places."

Dirtiest Phone Ever Tested

Believe it or not, the filthiest phones can spread the dreaded staph bacteria, which can cause everything from skin infections to meningitis. And where do these germs come from? Your hands and face.

Gerba recently tested 25 mobile phones and found the staph bug growing on nearly half.

Gerba also tested 10 phones from "Good Morning America" cast and crew. The results were shocking, especially the from the soundman's phone.

"This is the dirtiest phone I have ever tested," Gerba said. "He has somewhere between 10 and 50 million bacteria on his phone. If there is ever a new life form on this planet, it will be on this phone."

If you're worried about germs growing on your cell, Motorola has come up with a clever tactic -- some of its phones have an anti-microbial coating, which prevents bacteria from growing.

In the meantime, keep your phone to yourself and clean it frequently with anti-bacterial wipes.