Germ-free nation: is our obsession with cleanliness beginning to backfire?

Cleanliness is next to impossible, as the old joke goes, but you'd never know it at your local supermarket. There you'll find antibacterial hand soaps, antibacterial laundry detergents, antibacterial toothpastes and antibacterial toys. In some places, you can buy antibacterial mattresses, chopsticks and polyester. There are so many such products on the market today that antibacterials have become a $16 billion-a-year industry. The Washington Post reports that two-thirds of all liquid soaps on American store shelves today contain antibacterial agents.

>From this evidence alone, you might assume we'd be living in a germ-free environment by now, with infectious diseases all but wiped out. Either that, or we've become a nation of germophobes, unable to shake hands or turn a doorknob without immediately pulling out a Handi Wipe.

There's mote evidence for the later than for the former, which raises interesting questions. In fact, those disorders directly attributable to the strength of our immune systems such as asthma and allergies are on the rise. The number of asthma cases doubled from 1985 to 2000. And in the past 10 years, 700 new antibacterial products have been added to the market, leading some experts to suspect a troubling connection.

The possibility that we may be too clean for our own good has led some researchers to fear that antibacterials (and the desire for cleanliness to which they are a response) may actually be tendering us more rather than less vulnerable to disease. Whether that's true or not probably won't be established for years, but that doesn't mean you can't begin to make intelligent choices about your own approach to health based on existing evidence.

Hygiene Hypothesis

To grasp the science behind the experts' concern, it's important to familiarize yourself with the "Hygiene Hypothesis." That phrase attempts to convey the notion that some efforts to protect ourselves from germs may have proven counterproductive.

"The Hygiene Hypothesis seems to have taken root when it was observed that people with higher socioeconomic status--and therefore the cleanest living environments--also have the greatest problems with allergies and infectious diseases," explains James Dahlgren, MD, a University of California-Los Angeles (UCLA) toxicologist. "You're born with no immunities except what your mother gives you, which is why breast-feeding is so important. It isn't until you're 6 months old that your own immune system kicks in to protect you. The basic idea of the Hygiene Hypothesis is that the immune system has to be stimulated to develop properly, so that if a home is too clean, children don't develop the immunities that will protect them later in life."

Linked to this theory is the fact, first observed in highly sterile hospital settings, that pediatric patients treated with antibiotics were cured of one disease but were left vulnerable to others. "The antibiotics killed off the so-called non-resistant bacteria, but this left only the resistant ones--the ones the antibiotics could not kill--as a greater percentage in the body," says Dahlgren. This allowed the scrappiest bacteria to mutate and colonize at will, weakening the children and making it more difficult than ever for them to recuperate.

"It was out of that concern that doctors for years have been saying that you should not use antibiotics unless you absolutely have to--and then use the narrowest ones you can," Dahlgren says. "Unfortunately the pharmaceuticals industry has been pushing the broadest-spectrum antibiotics they have, which are also the most expensive. These kill more and more of the non-resistant bacteria, leaving more of the resistant ones." The phenomenon can be compared, the Boston-based Alliance for the Prudent Use of Antibiotics (APUA) explains, "to weeds that have overgrown a lawn where the grass has been completely destroyed by an overdose of herbicides."

Antibiotic Paradox

Stuart Levy, MD, who is chairman of the APUA, author of The Antibiotic Paradox: How the Misuse of Antibiotics Destroys Their Curative Powers and director of the Center for Adaptation Genetics and Drug Resistance at the Tufts University School of Medicine, says the idea that "germs should be destroyed, and kids should be raised in a sterile home is a mistake. If we over-dean and sterilize, children's immune systems will not mature. What worries me is that if we continue using antibacterials, we won't see [problems] until children get older, maybe 10 years from now."

Maybe so, but Sandra Kemmerly, MD, an infectious diseases specialist at the Ochsner Clinic Foundation in New Orleans, notes that dire conclusions drawn from the Hygiene Hypothesis "have been extrapolated informally into a lot of areas for which there is still no real scientific support."

But Kemmerly does acknowledge that these conclusions may offer significant insights nonetheless. People who are raised in less pristine environments often do seem hardier than those in more pristine ones. An October 2000 study by the National Jewish Medical & Research Center in Denver, for example, showed that household dust levels are higher in rural communities than urban ones--and that this dust appears to have a protective effect against allergies and asthma. Research presented in March 2003 to the American Academy of Allergy, Asthma & Immunology showed that exposure to a dog in the first year of life seems to strengthen a baby's immune system.