The Hygiene Hypothesis

Is there dust on your furniture? Are there handprints on your walls? Are there stains on your family room rug? Or food spills on the kitchen counter? This scene can be a veritable nightmare for mothers concerned about keeping their kids healthy and out of the pediatrician's office.

We've been raised to think that a dirty house is a breeding ground for germs. We also know that germs beget sick kids, and ill children are a cause of concern and worry for parents likely already stressed out from the rigors of everyday living.

It's no wonder we scurry around our homes armed with disinfectant, wiping down everything and everybody that crosses our paths. We desperately want our children to be healthy—a worthy goal, no doubt. But could this hyper-cleanliness actually be counterproductive? Some scientists would answer that with a resounding yes, citing the hygiene hypothesis.

What Is the Hygiene Hypothesis?

The hygiene hypothesis theorizes that a lack of early childhood exposure to dirt, bacteria, and other infection-causing agents can weaken the immune system and increase the risk of developing allergies and asthma. It basically indicates that exposure to bacteria—despite what the manufacturers of cleaning and antibacterial products will have you believe—might not be such a bad thing after all.

If you look around your home, you may find that you're using products you didn't even know were antibacterial. Antibacterial ingredients have become so prevalent that there are now antibacterial soaps, laundry detergents, toothpastes, body washes, hand lotions, shampoos, dish soaps, towels, bed linens, and many household cleaning products—all touted to wipe out harmful bacteria and lower a family's risk of infection.

Yet according to a study published in the March 2004 Annals of Internal Medicine, these products offer little protection against the most common germs (many of which stem from viruses) that cause illness. In the study, families that used antibacterial products developed runny noses, cough, sore throat, fever, vomiting, and diarrhea as frequently as the families that used non-antibacterial products.

If you're still worried about wiping out bacteria from your family's life, take note: Each square centimeter of your skin is host to an average of about 100,000 bacteria, and according to the Children's Health Environmental Coalition, "Most of the microbes on and around us are harmless. Bacteria naturally inhabit our skin, digestive tract, the soil, and our homes, helping to maintain a balance in both our internal and external environments. There's even mounting evidence that exposure to bacteria might be a good thing. According to the 'hygiene hypothesis,' bacterial assaults help children's immune systems to develop.'" ("Antibacterial and Disinfectants: Are They Necessary?" S. Hartman, 2003.)

In fact, the benefactors of these extreme hygienic practices are the very microbes that we are trying to do away with. As for the children we are trying to protect, they may be suffering on two fronts: This suppression of the immune system makes it more difficult for their little bodies to fight off and expel infection, and it heightens their risk of acquiring infections in places with high concentrations of illness—namely the doctor's office, daycare, and school.

Dr. Stuart Levy, MD, Director of the Center for Adaptation Genetics and Drug Resistance at the Tufts University School of Medicine, affirms that studies have indeed identified an increase in respiratory illnesses in homes that are excessively clean. "If we over-clean and sterilize, children's immune systems will not mature," he says.

Dr. Levy has also noted that overuse of these antibacterial ingredients could promote the development of drug-resistant "superbugs." This is similar to the increasing problem of antibiotic-resistant bacteria in our society caused from overuse of antibiotics.