WASHINGTON — It seems hard to go wrong with a hand soap that "kills 99 percent of germs" it encounters. But critics of anti-bacterial soaps in the home say there's plenty to be concerned about.

A government advisory panel will take a look at that tomorrow.

The popularity of soaps and other products claiming anti-bacterial properties skyrocketed in the last decade as consumers turned to them as a defense against household illnesses. Some people contend that a number of the products, particularly those that use synthetic chemicals rather than alcohol or bleach, pose the risk of creating germs that are resistant to antibacterials as well as antibiotics.

Those critics say antibacterials are no more effective than regular soap in reducing infections and illnesses. Unlike anti-bacterial products, regular household soap helps separate bacteria from the skin so they wash down the drain or attach to the hand towel when hands are dried. Anti-bacterial soap kills the bacteria outright.

Manufacturers disagree with many of the critics' claims; both sides point to studies they say support their point of view. A Food and Drug Administration panel of independent experts will take up these concerns in a public hearing.

The Nonprescription Drugs Advisory Committee will consider whether there is evidence that these products pose long-term hazards, as the critics contend. They can make recommendations on the sales and labeling of these products to the FDA, which ultimately has the authority to restrict availability of these soaps and related items.

FDA briefing documents posted on the Internet ahead of the meeting do not suggest any such ruling is imminent.

Critics like Dr. Stuart Levy, president of the Alliance for the Prudent Use of Antibiotics, say these products should be banned for use in healthy households. Instead, he says, keep them where they are needed: in hospitals and in homes with very sick people at greater risk if they get a bacterial infection.

"We run the risk of changing the kinds of bacteria we confront every day in the home," said Levy, a professor of medicine and molecular biology at Tufts University School of Medicine.

Here's how, he says: The small percentage of bacteria that survive a brush with the soap may develop resistance to it. What's more, he says, some surviving bacteria may have an improved ability to pump out all threatening substances, including antibiotics used to cure infections.

Those survivors may pass that mutation to their offspring, and the adaptation can come to dominate an entire population of bacteria, creating a resistance.

While Levy says that has happened in lab studies, there's no firm evidence it's happening in households. Brian Sansoni, spokesman for the Soap and Detergent Association, an industry group, said studies have found no link between the real-world use of anti-bacterial products and bacterial resistance.