They're the rolling work horses at the grocery store, but if you use a shopping cart you could be taking home a lot more than food and household supplies.

The growing germ scare in this country has many grocery stores offering disinfectant wipes for shopping carts. Many stores not only provide them at the entrance near the cart storage, but at meat counters and checkout stands.

Earlier this month a state legislator in Arkansas introduced a bill that would require grocer stores to provide sanitation stations -- all because of because of hidden germs on the cart seats and the handles.

So we took a closer look at these invisible hitchhikers and how concerned we should be about a health risk.

"I use them all the time!"

As the mother of three kids, Cindy Aiken of Mill Creek is very concerned about what's on those carts.

"There could be anything! I mean you could have flu viruses in there," she said.

It's a disturbing thought for parents, given how small kids have their mouths and hands all over the place. Some researchers insist shopping carts can carry more germs than public toilets.

University of Arizona scientist Dr. Charles Gerba, who's made a name for himself as a top "germ cop," says kids in carts only add to the problem.

"Many of them are diaper age and don't have good sanitary habits. You're putting your broccoli right where your kid's butt was," said Gerba in an interview this month on Good Morning America.

With graphic descriptions like that, who wouldn't be concerned? But I wanted to know, how much bacteria is really lurking?

The First Test

With the help of KOMO 4 Researcher Lorraine Collier -- and a hidden camera -- I tested 15 carts at more than half a dozen stores.

We worked with two local test labs: AMTEST in Redmond, and The Institute of Environmental Health in Lake Forest Park.

After consulting with their microbiologists and WSU Food Safety Specialist Karen Killnger-Mann, we tested for Listeria, Salmonella, Staph, E.Coli, general individual bacteria and total coliforms.

Total coliform bacteria are natural organisms that start out in soil, vegetation and the intestinal tracts of humans and animals (fecal matter) and have long been considered indicators of the overall degree of contamination. Small amounts are not uncommon and are typically not harmful. Large amounts raise the possibility of potentially harmful bacteria that could cause illness.

In our first test, we swabbed both the handles and the seats on five carts.

All of the samples tested free of Salmonella, E.Coli and Listeria.

But there was a lot of other bacteria.

Four carts had virtually no total coliforms. Two of the five carts had low levels of total coliforms and what are considered moderate levels of total bacteria. But one cart had total coliform count of 120, and an alarmingly high total bacteria count of 1.6 million. That's in the roughly 8-square-inch composite sample from the handle and seat.

Microbiologist Mansour Samadpour, CEO of IEH Laboratories, called that highly contaminated. The more bacteria, the higher your chance of getting bugs that can make you sick. Most of the bugs in that case most likely came from the shopping cart seat.

That is why so many grocery stores are jumping on the sanitizer bandwagon.

Still, many consumers, like Wendy Wyman of Seattle, just pass them by. "I've never noticed them," she said.

Wendy's daughter Merrily flat out doesn't bother. "I figure whatever bacteria I'm going to get on the shopping cart, I can get anywhere and everywhere else."

While scientists acknowledge that germs are indeed everywhere, Dr. Samadpour says for children especially it's a good idea to wipe carts and other surfaces that are prone to high germ exposure.

"It's prudent to definitely use some sort of sanitary protocol," he said. "You know, use a baby wipe."

Clean The Carts With Baby Wipes?

With the household cleaning industry offering increasing options for sanitizing practically everything with chemical wipes and cleaners, I wanted to find out if ordinary baby wipes would be as effective as wipes with disinfectant.

So we tested 10 more carts. This time, just the handles - both before and after using ordinary baby wipes, and over the counter disinfectant wipes.

The results?

Small amounts of mold. Some handles had small amounts of staph.

Dr. Samadpour says the most common problem with staph is skin infections. Staph bacteria are common in the environment and shed from people's skin.

Under the right conditions, Samadpour explained, staph bacteria can cause skin infections and even food poisoning. And some staph is resistant to drugs.

But even our scientists were surprised that the highest bacteria count on the handles was only 130 individual bacteria. That's considered low. Results of the other 14 carts were less than 50. Some samples had no bacteria at all -- likely the result of customers like Cindy Aiken who wipe the cart handles each time they go to the store.

The wipes work. It's also important to note that virtually all of the reports decrying shopping carts as filthy and germ-laden appear to be based on work originally published three or four years ago, before cart wiping because such a big trend in this area.

Most revealing of all in our test: ordinary baby wipes worked just as well as the wipes with disinfectant when it came to reducing and removing the bacteria. In both cases, the bacteria was either eliminated or sharply reduced.

Good Hygiene and Hand Washing Still the Best Solution

While the scientists we worked with were surprised there weren't more bacteria on the carts, they stress that just because there's bacteria present doesn't mean it's bad bacteria that can make you sick.

There's also concern that our over use of anti-bacterial products is generating more super bugs. In fact, PCC Natural Markets told me it does not provide wipes for customers because the wipes only give a false sense of security.

"We decided to call the experts just to find out what the experts were saying about this topic," said PCC's Trudy Biailc, who contacted the U.S. Centers for Disease Control. PCC also questions the wisdom using chemicals, which for some consumers can present a toxic hazard themselves.

"We were told there's little or no evidence, there's no data to support the idea that shopping carts are even a problem," she said, quoting the CDC's lead microbiologist in epidemiology Dr. Matthew Arduino.

Here's what the centers for disease control told me: "We don't link scores of infections to environmental surfaces like shopping carts. Shopping cart germs are not a major problem."

Local health officials concur.

But if it makes you feel better, and certainly if you have young children, are pregnant or have a weak immune system, the general consensus is you can greatly reduce the germs by wiping -- even with simple baby wipes. Just don't forget to wipe the seats.

Also remember that even if you wipe the cart, it will be re-contaminated as soon as you start handling products, produce and meat. Even more if you plop a kid in the cart. Something to think about next time you take a free food sample with your bare hands.

All health experts I talked with agree that the absolute best thing you can do to avoid getting sickened by germs on any surface is to wash your hands well and often. And keep them away from you eyes, nose and mouth. And when you can't wash, an instant sanitizer with at least 60 percent alcohol will go a long way to keeping your hands germ-free.