It's no secret that Americans respond to the word "bacteria." Last year, more than $135 million worth of anti-bacterial liquid dish detergents alone were bought in this country's food, drug and mass merchandiser stores (not including Wal-Mart), according to data from ACNielsen.

And that, actually, represents a 10.6 percent decrease from 2003, according to the Schaumburg-based research firm.

But the anti-bacterial category continues to grow broader and more intriguing with the recent introduction of a whole genre of bacteria-busting home appliance. Namely: the toothbrush sanitizer.

The claim: There are "millions" of potentially harmful bacteria (including, perhaps, scary ones like salmonella and E. coli) living and breeding on the bristles of our wet toothbrushes between uses. And, according to these claims, we're sticking those germs not only into our mouths the next time we brush, but potentially into our bloodstream should we abrade our gums with the bristles.

The supposed fix: a small electric appliance ($50 to $80), meant to sit on the bathroom counter, that uses either a steam/dry heat method or ultraviolet light to rid the toothbrush bristles of more than 99 percent of those germs.

The big questions: Do we really need this device? And how did we survive this long without sanitized toothbrushes?

We turned to six medical/health professionals for some answers.

They include: a dentist; a dental hygienist; a microbiologist; a periodontist; an infectious disease physician; and the Centers for Disease Control and Prevention in Atlanta. (The American Dental Association and the American Dental Hygienists' Association have no official position on toothbrush sanitizers.)

We asked them to respond to some of the startling statements about bacteria and toothbrushes that are being made by the makers of toothbrush sanitizers that hit the market recently.

They are Germ Terminator and VIOlight. Both have launched aggressive media campaigns and the VIOlight, in particular, has caught the attention of many a design buff. The chic little unit, whose frosted top glows a blue-violet hue when the UV system is working, was designed by none other than Philippe Starck, master product designer.

The bottom line from our pool of experts is this, though: The toothbrush is not the biohazard that these manufacturers would like Americans to believe.

Only the dental hygienist sang the praises of sanitizing. The others we consulted said there is no scientific evidence to support the need for it-and perhaps, more important, that some of the information being presented by the makers of these appliances is just plain misleading.

First of all, the notion that "millions" of bacteria might be lurking on our toothbrushes should not make anyone cringe. The human mouth harbors "billions" of bacteria, according to Christine Wu, a microbiologist by training and a professor of periodontics and associate dean for research at the College of Dentistry, University of Illinois at Chicago.

"You could have billions of bacteria in 1 milligram of dental plaque," Wu says. "The oral cavity is a very, very complicated ecosystem." Some are good bacteria. Some are bad.

Some, quite naturally, get onto our toothbrushes when we're brushing.

The CDC recommends rinsing the toothbrush thoroughly with water after using it and allowing it to air dry in an upright position. For the most part, organisms need moisture to survive.

Will all the bacteria be removed from those bristles?

"No, probably not. But there's no evidence that the bacteria remaining pose a health threat to you," says Dr. William Kohn, a dentist by training and the associate director for science, Division of Oral Health at the CDC.

There is no evidence, says Kohn, "that the next time you brush - somehow, all of a sudden, these bacteria have become new, enhanced organisms that are going to cause disease."The germs in our mouth don't come from our toothbrush, explains Dr. Rebecca Wurtz, an infectious disease physician and associate professor in the Department of Preventive Medicine at Northwestern University Feinberg School of Medicine in Chicago. "The germs are naturally in our mouths and 'sanitizing' a toothbrush won't change that," Wurtz says.Some of those germs, indeed, will travel into our bloodstream if our gums bleed even a little when we're brushing, Wurtz says. But "it's a tiny number of germs that your immune system very quickly scoops up," Wurtz says. "It happens every day of our lives. Using a toothbrush makes that happen. Using a so-called 'dirty' toothbrush doesn't make it happen any worse."If anything, Wurtz continues, a worn-out toothbrush poses a bigger health hazard than an unsanitized one. The nylon bristles actually get sharper as they wear. "You are more likely to injure your gums" with a worn-out brush, says Wurtz, not to mention the fact that a brush with splayed bristles isn't doing an effective job of cleaning the teeth.Although they are careful in the wording of their claims about the role of "dirty" toothbrushes, the makers of both VIOlight and Germ Terminator like to point out the link between oral disease and cardiovascular disease-the fact that people who have periodontal disease also tend to have thicker carotid arteries, a strong predictor of stroke and heart attack.(In February, the heart journal Circulation published a study that, for the first time, got to the microbiology of that association. It found that people who had higher proportions of four specific periodontal disease-causing bacteria in their mouth also had thicker carotid arteries. What the study did not determine was cause and effect - whether periodontal disease causes cardiovascular disease or vice versa. The study was not designed to take that on, nor did it discuss toothbrushes.)Dr. Panos Papapanou, a periodontist and one of the authors of the study that was published in Circulation, said he does not see the role of "dirty" toothbrushes in this whole scenario."It doesn't make sense," says Papapanou, who is professor and chair of the Section of Oral and Diagnostics Sciences and director of the Division of Periodontics at Columbia University School of Dental and Oral Surgery in New York."Your toothbrush could be sterile or not sterile," Papapanou says. "It's your own bacteria (in your mouth) that confers that risk."Which is the same argument Kohn and Wurtz make about our mouths being the real harbor of germs, not our toothbrushes.The makers of both VIOlight and Germ Terminator go a step further, though, in their claims about toothbrush bacteria. They say that not all the germs on those bristles necessarily came from our own mouths.Cross-contamination of brushes could occur in a family cup holder, should the brushes touch one another, say Joel Pinsky, chief executive officer of VIOlight, and James Song, inventor and chief executive officer of Germ Terminator.(Neither Pinsky nor Song is a medical professional. Song has a background in science, though. He studied biochemistry in college some 20 years ago and also owns a company that deals in nutritional supplements and body-care products. Toothbrush germs have bothered him since he was a kid; as a college student he used to grow germs that he took off his classmates' toothbrushes. Pinsky's background is in manufacturing and distribution. He was previously in the leather goods business. Both have submitted their sanitizers to independent laboratories to substantiate their claims that these devices do, indeed, kill the germs they say they do.)

Pinsky and Song also say that airborne bacteria (including fecal organisms, a result from toilet spew) could land on our toothbrushes.To that, Wurtz says: "There are airborne germs around us all the time. And they're not any more likely to settle on our toothbrushes than to settle in our lungs."As for the particular concern about fecal bacteria, which could contain E. coli, landing on our toothbrushes, Kohn at the CDC says he is "unaware" of any published scientific report that shows this to be a cause for concern.Wurtz says even if someone was misguided enough (and she does not recommend this) to put her toothbrush on the floor next to the toilet and even if there was a fine mist spew, "even then, you don't have to be concerned - other than it's gross." The aerosolized germs that spew from the toilet, says Wurtz, "have already been in our intestinal tracks."About the possibility of germs spreading by the bumping of toothbrushes in the family cup holder, Chicago dentist Dr. Trucia Drummond believes that is "probably true" - but certainly not the only way illness spreads through a household. Drummond recommends keeping toothbrushes apart. So does the CDC in its recommendations for proper toothbrush care."There's a lot of things that are theoretically possible when you talk about germs," Kohn says. "You can invent all kinds of scenarios, but you still have to show: Is there any evidence whatsoever that people are actually getting sick from this ('dirty' toothbrushes)? And there is none."

Both Song at Germ Terminator and Pinsky at VIOlight debate that.Song acknowledges that "there isn't a $100 million study" that proves that toothbrush germs cause disease and, in particular, chronic inflammation that may surface later in life and lead to heart disease, stroke and a host of other health problems. It is one of Song's key beliefs, which he theorizes in "Why Your Toothbrush May Be Killing You...Slowly," a book he wrote and published himself."I'm trying to make the link, that association," says Song, who believes the bottom line is simply this: "A clean toothbrush is better than a germ-infected one."Maria Perno Goldie, a San Carlos, Calif.-based dental hygienist and a past president of the American Dental Hygienists' Association, agrees with that thinking-and compares using a "dirty" toothbrush to eating off last night's dishes without washing them."Would eating off those dirty dishes make us sick? Maybe. Maybe not," says Perno Goldie, who notes that as a dental hygienist she is in the business of preventing disease.As for Pinsky at VIOlight, he believes that most people don't know how they get sick. So "why not wash your toothbrush?"Both Song and Pinsky apparently have struck a chord with more than a few believers.Song says he has sold 400,000 Germ Terminator units since launching the product 1½ years ago. And he says he has been approached by several "big companies" and is in the process of negotiating distribution rights with one of them.Pinsky says he has sold 10,000 units since he launched VIOlight in October.Both products are available on the Internet (www.germterminator.com; www.violight.com) and at certain locations of certain mass-merchandise stores such as Kmart.These aren't the first toothbrush sanitizers that ever came to be. At least one other, the Purebrush brand, has been on the market since the early 1990s.The big names in oral care aren't in the toothbrush sanitizer business though.Philips Sonicare offers no such appliance. And neither does The Gillette Co., which has the Oral-B brand. "We don't believe there's any danger with using a toothbrush as normal and letting it air dry," says Michele Szynal, a spokeswoman for Oral-B.Although Kohn at the CDC doesn't see any benefit from using these devices, he also says toothbrush sanitizers probably aren't harmful either. And for people who are "really germ conscious," a toothbrush sanitizer might bring them a certain peace of mind, says Kohn-even though it might not be doing them any good.