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Are Antimicrobial Soaps Breeding Tougher Bugs?

And that message has found a following. According to Mintel GNPD, a market research firm based in Chicago, 71 percent of adults who do some or all of the household cleaning "prefer [to use] antibacterial and germ-killing cleaning products."

Moving Beyond Soap

The first mass-marketed antimicrobial product was put out in 1948 by the Dial Corp. "Aren't you glad you use Dial?" the marketing campaign asked: "Don't you wish everybody did?" The implied biology lesson -- a correct one, as it happens -- was that bacteria are partly responsible for body odor. The new deodorant was a hit; Liquid Dial followed in 1987, and a waterless hand-sanitizing gel in 1998.

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Major marketing breakthroughs came when companies figured out how to put the antimicrobial compounds into more than just soap. Hand sanitizers were swiftly followed by germ-killing plastics and synthetic fibers, and suddenly nearly every product in your house -- from air filters to wallpaper, bathroom appliances, door frames, food storage containers and the kitchen sink -- could be part of the fight against bugs. Check your computer keyboard; chances are it was treated with a film of Microban, one of the leading trade names for triclosan.

In the wake of such scares as the bird flu, E. coli in food and MRSA, Mintel says the germ-killing marketplace has become even more fertile. In one recent three-year period, new product launches increased by more than 700 percent, from 200 products introduced in 2003 to more than 1,600 in 2006.

For many Americans, soap -- the plain old soap your grandmother used -- is simply not enough.

New and Improved?

Plain old soap relied for its chemistry primarily on animal and vegetable fat, and its cleaning power came essentially from its ability to create suds and lather, as the soap molecules formed a thin film around dirt, allowing it to be washed away under running water. Down the drain go not only bacteria but also viruses, such as those that cause the common cold. Compounds like chlorine, alcohol and peroxide (which kill immediately and at random rather than inhibiting the growth of bacteria) were often added to give soap extra cleansing kick. Those products are also commonly found in travel wipes and towelettes.

Adding specifically antibacterial agents seemed a natural next step. And although Levy and other scientists don't dispute that these chemicals can kill bacteria, they argue there's no evidence they do any good. "No study has shown that," Levy says. What's more, many illnesses such as flu and the common cold, which prompt people to wipe down telephone handsets and doorknobs, are caused not by bacteria but by viruses -- and antibacterials can't slow a virus at all.

Levy cites several studies, among them a 2004 study in the Annals of Internal Medicine, in which 228 New York households were divided randomly into two groups: One used regular soap and water; the other antimicrobial soap. There were just as many instances of vomiting, diarrhea, fever, sore throat, cough, runny nose and pinkeye among the antimicrobial users.

"For general use, antibacterial soaps are not superior to cleansing with regular soap and water," says Shmuel Shoham, an infectious disease specialist at Washington Hospital Center. His view is backed by the conclusions of an advisory panel to the Food and Drug Administration, which voted 11 to 1 in 2005 that, when it comes to keeping us healthy, antibacterial soaps and washes are no more effective.

But the New York study's lead author, Elaine Larson of Columbia University concedes that antibacterial soaps may offer benefits when there are medically vulnerable people in the house: someone who is "ill, immunocompromised, a neonate [newborn], or elder." A point that Sansoni emphasizes: Health care is not just in the hospital anymore, he says, it is in our homes.

Hazardous to Your Health?

While the arguments continue over whether antibacterial soap does any good, there's a second concern over whether it may actually do harm.

"Evidence is accumulating," Shoham says, "that chemicals used in antimicrobial soaps may be causing bacteria to become more resistant to commonly used antibiotics."