WASHINGTON — If cleanliness is next to godliness, modern America is the land of the faithful — fighting the good fight against today's so-called superbugs with sparkling countertops and well-washed hands.

WASHINGTON — If cleanliness is next to godliness, modern America is the land of the faithful — fighting the good fight against today's so-called superbugs with sparkling countertops and well-washed hands.

Our culture's cleanliness obsession has been fed by a booming business in household products that promise the virtue of sterility. According to estimates by the Environmental Protection Agency, our antimicrobial crusade has us spending almost $1 billion annually on soaps and detergents, toys and cutting boards, bedsheets and toothbrushes, all of them treated with chemical compounds designed to kill the germs that cling to them. At the forefront of this product niche is the antimicrobial hand wash, commonly fortified with the bug-battling chemical triclosan.

It may be a dangerous, germ-filled world out there, but with your little bottle of — choose one: Dial, Safeguard, Palmolive — you can stroll worry-free through it.

Or so you may think.

The problem about our obsession with killing germs, some scientists and public health advocates warn, is that it may ultimately do us more harm than good.

Chief among those skeptics is microbiologist Stuart Levy of Tufts University School of Medicine, president of the Alliance for the Prudent Use of Antibiotics (APUA). Levy's research has led him to question why "antibacterial ingredients, once successfully used to prevent transmission of disease-causing micro-organisms among patients, particularly in hospitals ... are now being added to products used in healthy households ... even though an added health benefit has not been demonstrated."

That's happening, Levy says, despite several "potential negative consequences" of these products, including weakening the immune system, which could lead to a greater chance of allergies in children, and their possible link to the emergence of antibiotic resistance — the very problem that is making some diseases, such as methicillin-resistant Staphylococcus aureus, or MRSA, so difficult to treat.

Members of the manufacturing industry, meanwhile, including Brian Sansoni, vice president of communications at the Soap and Detergent Association, contend that consumers can use these products "with confidence" because "they reduce or kill germs on the skin that can make us sick."

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."

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.

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.

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.

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."

Levy lays out this theory in his book "The Antibiotic Paradox": Antibacterial products leave residues on the surfaces where they are used. The active ingredients linger and continue to kill the bacteria, but not effectively or randomly. The naturally stronger bacteria that survived the initial assault develop new defense mechanisms against the chemicals. This selection process gives rise to a new generation that is resistant to the offending compounds.

Certain bacteria also develop "cross-resistance" — transferring their new and improved defenses to bacteria fighting other types of antibiotics.

This is essentially the same scenario as the emergence of drug resistance from the overuse of antibiotic medications.

But Sansoni says that transferring the drug resistance phenomenon to hand cleaners is one of the "greatest suburban myths," for which, he says, there is no scientific evidence. Indeed, scientists looking for the emerging resistance have found it only in their own labs, in Petri dishes. Triclosan, for example, has been shown to make bacteria undergo mutations and create resistance — but only in the laboratory setting. Not on your kitchen counter.

Beyond the drug-resistance worries, some scientists are concerned that antimicrobial soap is an indiscriminate killer.

Some bacteria are bad for us, but some are good. The antimicrobials kill both. And when the good bacteria are gone, there's more room for the bad bacteria to grow, raising our risk of becoming sick.

Besides, a germ-free environment may actually weaken our immune systems, some critics say. They are referring to the Hygiene Hypothesis — the theory that children build their immune systems from infancy by putting in their mouths all those dirty objects they find lying around.

A number of studies have linked the development of allergies, asthma and skin problems in children to their having been raised in environments that are too sterile. "You need a little dirt," Levy says, "to train your immune system correctly."

The takeaway message: If you are worried about MRSA, E. coli, SARS, influenza or simply the common cold, you already know you should wash your hands.

Thoroughly.

Regular soap and water will do.

Ranit Mishori is a family medicine resident at Georgetown University/Providence Hospital