10 Germ Myths Under the Microscope

Experts Tell Which Germ Concerns Are Legit

ABC News Medical Unt

Dec. 29, 2008—

As you take steps to avoid the germs and viruses that proliferate as winter progresses, you've no doubt received a good share of advice on how to avoid catching whatever's going around.

ABCNews OnCall+ spoke with experts about some of the popular myths about germs that tend to spread as fast as the bacteria themselves this time of year.

Is a dog's mouth cleaner than a person's? How unsafe are public toilet seats? Some of these questions lack hard data, and the study findings sometimes conflict.

So before taking advice from your friends, you might want to check their wisdom about our microbe neighbors.

Fact or Myth? You can get infections or illnesses from sitting directly on a public toilet seat.

Answer: Myth

"Just sort of sitting on the seat and having that contact with the skin on your butt isn't going to be a way of transmitting an infection," said Elizabeth Scott, co-director and founder of the Simmons Center for Hygiene and Health in Home and Community Settings at Simmons College in Boston.

"I think that one's associated with the fact that we all find public toilets very disgusting," she said, adding that you were more likely to get sick from touching the toilet seat or the flush handle with your hand.

Dr. J. Owen Hendley, professor of pediatric infectious disease at the University of Virginia Children's Hospital, said that this myth has been a persistent one.

Of getting an infection, he said, "I guess you could, but I've never known of a documented case where that actually happened."

But that has not stopped the myth. Hendley noted that the concern might have originated with a fear that syphilis could spread through toilet seats. He said that that fear is likely behind the design of many public toilet seats in which the seat itself is open in the front, preventing contact between the person and the seat in that area.

But the knowledge that sitting directly on the seat doesn't spread the germs doesn't seem likely to make it more appealing.

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"I couldn't imagine it [spreading infection]," said Hendley. "Which is not to say I would like to go into a public restroom and sit down on the toilet seat."

Fact or Myth? If you keep your toothbrush within 6 feet of your toilet, you're brushing your teeth with toilet water.

Answer: Possibly a Fact

"You get a great spray out of the toilet when you flush it," said Charles Gerba, a professor of microbiology at the University of Arizona. "This throws bacteria out of the toilet."

Gerba's research showed a spray coming out of toilets when they are flushed. That spray goes out and puts fecal bacteria and whatever else is in the toilet all over everything else in the bathroom, right?

Maybe not. A few years ago, the Discovery Channel's "Mythbusters" tackled the issue.

In its tests, the show placed toothbrushes near the toilet, in a bathroom cabinet and in the kitchen of a house.

At the end of the test, the show declared the toilet-toothbrush-shower a myth, with all three toothbrushes having similar amounts of fecal bacteria, regardless of placement.

So we know there's a spray when the toilet gets flushed, but it's unclear how far it travels and what ends up where.

Ultimately, the problem may be that there hasn't been a peer-reviewed study of toothbrush hygiene. We don't know where the bacteria travel, and we don't know the source of bacteria that may have ended up on the toothbrushes placed in various areas.

"A lot of the droplets that are generated when you flush a toilet, they are too large to spread probably more than a foot or two," said Sattar.

Fecal bacteria means the bacterium E. coli, which is found in fecal matter, among other things. While often used to gross someone out about bacterial contamination, just finding it doesn't mean the germs came from the toilet.

So it's not entirely clear that your toothbrush is showering in your toilet water just because it's nearby. But it may not be a bad idea to put the lid down when you flush.

Fact or Myth? The blowing air from a hand drier in a public restroom spreads germs.

Answer: Myth

Syed Sattar, a professor emeritus of microbiology at the University of Ottawa, has looked into this issue, and was more than happy to declare it an outdated concern.

"That is certainly a myth, because we have done our own studies in that regard," he said.

Sattar said his team had sampled the air around driers in various public restrooms as people were using them and found no increase in bacteria.

As to the rumor that dust accumulates inside, he said his team had taken apart multiple hand driers in places like bus stations and busy shopping centers and also found nothing.

The real worry about hand driers, said Scott, is having to touch something to start them.

"It's always good to look for systems that don't require you to touch," she said, because the buttons will accumulate germs.

Ideal restrooms, Scott said, wouldn't have doors or handles for the faucet, and would have electronic eyes to start hand driers, faucets and flush mechansms on toilets.

"No-touch is ideal," Scott said.

Fact or Myth? Antibacterial soap keeps your hands cleaner than regular soap.

Answer: Myth

This myth may stem from a misconception about what we do when we wash our hands. By rinsing in soap and water for at least 20 seconds, we aren't supposed to be killing bacteria, but simply getting germs and viruses off our hands.

"If you can get to a sink and you can wash your hands thoroughly 15 to 20 seconds with regular soap and then rinsing -- that is the most effective method of 'de-germing', or removing germs from your hands," said Scott.

She noted that washing with soap and water doesn't remove all the microbes from our hands, because some are an important part of our skin, and even if we did kill them, they would return.

Given that regular soap and water removes the germs, there is no need for an antibacterial agent, and it probably won't work anyway.

"The speed of action of these ingredients that are added is rather slow, so that they are not there on the hands long enough to present the desired level of reductions," said Sattar.

So the antibacterial agents added to soap, typically triclosan, isn't effective in this case but may present problems, as our next myth explains.

Fact or Myth? Alcohol rubs cause bacterial mutation and help create resistant strains.

Answer: Myth for Alcohol Rubs, Possibly a Fact for Antibacterial Soap

The alcohol-based antibacterial rubs are effective enough that they do not create resistant strains, explained Scott, but the antibacterial soaps may present a hazard.

While the alcohol rub stays on the hands and is not meant to be rinsed off, the antibacterial triclosan is rinsed off before it can do all its work and then enters the water supply.

"The reason I don't like it is because it gets in the water supply and stuff like that," said Hendley of his opposition to triclosan in soap.

Scott notes that resistant strains of bacteria have been created in labs using triclosan, although it remains to be seen if it will happen in the natural environment.

"It's something that's been observed in the laboratory, and it's something that needs to be researched," she said.

For Sattar, the long-term risks of triclosan in the environment also need to be looked at.

"Their accumulation in the environment or chronic exposure to them on a long-term basis, especially for children, may have a long-term risk that we will not discover until later on," he said.

Ultimately, Sattar said, antibacterial soap doesn't do enough to justify its use. "Don't take risk without a demonstrated benefit," he said.

Fact or Myth? Sponges typically don't help keep your kitchen cleaner, they just spread germs around.

Answer: Fact

Sponges pick up various contaminants when used to clean used to clean dishes or surfaces that food has touched, and those contaminants can be easily spread.

"Sponges are probably the most germ-laden object in the household," said Gerba. "They usually contain 10,000,000 or more fecal bacteria. In a study we did some years ago, we found salmonella in 10 percent of them. The reason is that they are wet and pick up food for the bacteria. They do a great job of spreading bacteria around the household."

So in order to keep sponges from being bacteria farms for your kitchen, several steps should be taken.

Hendley said he maintains separate counter and dish sponges and makes sure to have detergent in the sponge whenever he uses it.

Scott said that maintaining separate dish and counter sponges is key.

"I think the best practice is to keep the sponge at the kitchen sink for washing up, and to use paper towels for wiping down kitchen surfaces," she said.

Sponges can be placed in the dishwasher or laundry to decontaminate them, although the research on how much that helps remains unclear.

Perhaps the best way to clean sponges is by microwaving them, but it's important to ensure that they are wet before putting them in.

Fact or Myth? Plastic cutting boards are more sanitary than wooden ones.

Answer: Fact -- if the board's handled right

The difference in sanitation has little to do with the cutting boards themselves.

"[The cutting boards] are about the same," said Gerba. "In the average household they have 200 times more fecal bacteria that the average toilet seat."

Scott explains that the wear on the cutting board affects its cleanliness more than the material from which it's made.

"The most important thing is, whatever cutting board anyone's using, it's not badly scoured," she said.

So why did we deem this a fact?

As Scott explained, a plastic cutting board is easier to clean, by bleaching it at the sink or putting it through the dishwasher.

In any case, she noted, separate cutting boards should be used for raw chicken or beef and vegetables.

And ultimately, the plastic cutting boards are more sanitary, Scott said, because they're cheaper -- so people are more likely to throw them out and replace them. Fact or Myth? The makeup at a cosmetics counter is unsafe to use -- it harbors a multitude of germs.

Answer: Probably a Fact

The safety of using sample cosmetics from the counter may depend on how they're used, but the prospect of what could be in that makeup is enough to keep Scott away from them.

"I don't like that idea at all," she said. "There is the possibility that someone handled the cosmetic who had pathogens on their hands or a skin infection or an eye infection. That all might be transmitted by that cosmetic."

There doesn't appear to much hard data on what the cosmetics at the counter contain, but their usage could lead to the spread of infection.

Scott's advice is to stick to single use samples and avoid the communal beauty sources.

Fact or Myth? A dog's mouth is cleaner than a person's mouth.

Answer: Myth

If you heard this myth, it probably came from a dog lover as they justified why they let their pet lick their face.

And in one sense, they may be right: A dog's mouth is likely to contain fewer microbes that are harmful to humans.

"If I were forced to be bitten by a dog or a human, I'd take a dog," said Hendley.

But that doesn't mean a dog's mouth has fewer microbes, or that it's "clean."

"I'm thinking, what was the dog last licking?" said Scott.

Hendley and Scott noted that dogs tend to lick themselves, particularly after scraping themselves, and their mouths tend to come in contact with animal feces.

Scott also noted that germs can be picked up by stroking the animals, and you should wash your hands anytime you touch them.

Fact or Myth? Airplanes are a major source of contamination because of the recirculated air.

Answer: Unclear

Airplanes put many different people in a confined space for several hours with the same air. Small wonder that some see planes as flying germ houses.

But while germs may once have recirculated freely, new technology may have removed some of the flight concerns.

ABCNews OnCall+ has previously looked at the issue, and travel can increase risk of flu (which comes from a virus, not a germ), but that is a concern in any crowded area, not just an airplane.

The recirculated air, however, is not as much of a concern as it may once have been.

"It probably was true in the sense that inside of an aircraft cabin, if filled to capacity, you would have a lot of people breathing germs in and out," said Sattar.

But, he said, "More recent aircraft design has created engineering controls which reduce that risk."

Sattar notes that HEPAs, or high efficiency particulate arresters, which were developed around World War II, trap tiny particles in the air so that any particle that might be carrying viruses or bacteria is caught when viruses pass through the air system in the aircraft.

So planes, like any crowded area, pose an increased disease risk, but it isn't clear how much, if any, of that is due to the recirculated air.

Sattar also noted that the World Health Organization will be examining this issue to ensure that passengers aren't sharing illnesses with their fellow travelers.


Cold & Flu season is here! Visit the ABCNews.com OnCall+ Cold & Flu Center to get answers to all your questions about these nasty germs.