How Dirty Are Your Shoes?

June 16, 2008 — -- Do you wear your shoes in the house or leave them at the door? It's an especially important choice for people with small children who play on the floor.

In some countries and cultures, it's scandalous to walk into a home with shoes on. But in the U.S., most people do.

"I don't really think that much about it," said New Jersey mom Michelle Ciocon.

"Good Morning America" tested the bottoms of eight different people's shoes, as well as two dogs' paws, for bacteria. Ciocon's shoes contained the most bacteria of all — 66 million organisms.

It's no reflection on her; she probably just stepped directly in something.

In a recent study, researchers at the University of Arizona found nine different species of bacteria on people's shoes. These types of bacteria can cause infections in our stomachs, eyes and lungs.

The study also found bacteria live longer on our shoes than in other places. As we walk, we constantly pick up new debris that feeds the growth of more bacteria.

The researchers tested to see if bacteria on shoes would transfer to the tile floors in a house. More than 90 percent of the time it did. Carpeting harbors bacteria even more.

"GMA's" test results were "dirtier than a toilet seat," said Jonathan Sexton, a research assistant at the University of Arizona's College of Public Health. "Toilet seats generally have 1,000 bacteria or less, and these are in the millions so there's a lot more bacteria here."

The results troubled Ciocon.

"I'm concerned," she said. "I'm going to make sure everyone takes their shoes off from now on. As soon as they get to that door, their shoes are going to be off."

Children under age 2 are the most vulnerable to the germs we track into the house, because they play on the floor and put their hands in their mouths an average of 80 times an hour.

"That means that your child can possibly be exposed to every single bacteria that you picked up on your shoe [...] all the bacteria from the park, the store, everywhere you went that day," Sexton said.