The Dirt on Being Skeaky Clean
How clean is too clean? How dirty can we be and still be healthy? No matter which hygiene question you prefer to ask, this is one matter best mediated by one hand washing the other.
Let Dr. Gary Noskin explain. “Always stop to wash your hands when they are visibly soiled,” said Noskin, medical director of infection control at Northwestern Memorial Hospital in Chicago, who has conducted numerous studies on the subject. “We should wash them any time we come in contact with bacteria or viruses, such as when we touch our noses or use the bathroom. Our findings show using soap, water and friction for 25 to 30 seconds is what’s most effective.”
Passing bacteria and viruses among us is the most common way we get sick with any infectious disease, including colds and flu. Hand-to-hand contact is a major culprit, so is touching items such as faucet handles or telephones that are harboring bacteria and other germs. That’s why hand-washing is a must for daily health.
Yet an ongoing scientific debate focuses on whether there is such a thing as being too clean. Researchers have been asking--and finding--that maybe our homes and indoor environments are overly resistant to germs. There is growing skepticism about whether antibacterial soaps are necessary. The American Medical Assn. recently asked the government to expedite review of such products to determine if they actually pose a health threat by encouraging the growth of super-resistant bacteria.
It has even been argued that a young child covered head to toe in grime might be strengthening his immune system rather than just tracking in mud. The debate breaks into two parts. One issue is keeping our hands and bodies clean. The other hot point is exposure to allergens ranging from dust to pollen to cat dander, especially among young kids.
Dr. Stuart Levy of Tufts University School of Medicine in Boston is a critic of new antibacterial soaps and cleansers. He said these products are providing a false sense of security among consumers and “could be promoting superbugs that might otherwise be kept in check.” The argument is simple enough. Using antibacterial products wipes out not only the harmful bacteria and germs but also “good” bacteria.
Levy said household standbys such as chlorine bleach, hydrogen peroxide and alcohol are antibacterial cleaners, but once you use them, they vanish. The newer synthetic products leave a residue to kill bacteria for an extended period, not allowing the good bacteria to reestablish themselves. Good bacteria are vital for the intestinal tract, fighting off germs. They also help the body make vitamins and protect it at the mouth and skin layer.
“The vast majority of bacteria are out there serving a purpose for us,” said Levy, director of the Tufts center for adaptation genetics and drug resistance. “They help our intestinal tract mature, and they help our immune system mature.”
Levy explained that antibacterial soaps have no proven benefit over mild soap and water. He recommends using stronger hand cleansers only when someone in the household is seriously ill or has lowered immunity. Wiping hands on a paper towel might even be most important, he said, even if your hand-washing is shorter than the optimal half-minute. The paper towel gets organisms off the hand even if you don’t kill them. Studies indicate that using a paper towel is better for removing bacteria than the hot-air dryers installed in public bathrooms.
Other findings show that using enough soap is a key factor, though no one has agreed on how much soap is enough, just that each of us tends to use the same amount of soap as habit. In any case, Noskin said, the idea of keeping our hands totally clean is both unnatural and unattainable. Better to accept that frequent hand-washing should be part of your day.
“Hands aren’t sterile, they will never be sterile,” he said.
As for the second part of the too-clean debate, Levy makes frequent presentations about what is known as the “hygiene hypothesis.” It holds that when small children do not get enough exposure to bacteria, the immune system can overreact to pollen or dust or other typically harmless substances. It is based on the premise of killing the good bacteria and reducing competition with the bad bugs.
Parents might think they are doing the right thing using antibacterial soaps and household cleaners, strong detergents, antiseptic diapers and minimizing exposure to children and pets. Now it seems they might need to think again.
“I have been studying the data from Europe for 10 years,” Levy said. “Europeans with the highest air pollution report the least amount of allergies.” In addition, one recent Italian study showed exposure to bacteria is essential for development of an infant’s immune system.
“It’s just like a child needs exercise to build strong bones and muscles,” Levy said. “A child’s immune system needs its own workout to develop a normal resistance to infections.”
All of that makes an argument for letting the kids get mud under their fingernails. Statistics show that Americans typically spend 93% of their time indoors, often in newer structures that are tightly sealed no matter what season. As a result, what once were harmless things we breathed or touched--pollen, animal hair and fur, dust, mold--are increasingly “attacked” by our own immune systems.
In August, the New England Journal of Medicine published a study of more than 1,000 Tucson children that further advanced the hygiene hypothesis. It showed that exposure of youngsters to older children at home or to other children in day care significantly protects against the development of asthma.
Then, in March, noted University of Virginia researcher Thomas Platt-Mills published a paper in the British medical journal, the Lancet, indicating that a cat in the home actually can decrease the risk of asthma. It turns out cat dander leads the body to produce certain antibodies that ultimately strengthen the immune system.
Not every researcher is taking a shine to the hygiene hypothesis. Charles Gerba is a University of Arizona microbiologist concerned that Americans will become lackadaisical at a time of increasing high-profile germs such as E. coli O157:H7 and salmonella bacteria, plus hepatitis viruses. “In some ways, you can never be too clean,” Gerba said. Gerba explained that some antibacterial products are unnecessary--he names antimicrobial window cleaners and toothbrush handles--but that the new soaps and cleansers can offset the reality that most Americans aren’t likely to wash their hands with soap and water for the required 25 to 30 seconds.
“The average is four seconds,” Gerba said. “Another thing is, most of us clean our homes less than ever. We spent 25 hours [a week] on the home in the 1950s; now it’s closer to 15 hours.”
What’s more, surveys show that Americans wash their hands only about two-thirds of the time after a bathroom trip and roughly half the time after sneezing or petting the dog. Another criticism of the hygiene hypothesis is that it takes some attention away from use of antibiotic medications. The federal Centers for Disease Control and Prevention estimates that 50 million unnecessary prescriptions for antibiotics are written each year.
