Coming Soon to a Tap Near You : If fluoride--the chemical credited with reducing teeth decay--isn’t already in your water supply, expect it. It’s now the law.

It’s considered the most thoroughly studied public health issue in the country and one of the most cost-effective ever.

Now, 50 years after the benefits of fluoridated water were discovered, nearly all Californians will soon--finally--benefit from it.

A bill signed by Gov. Pete Wilson in October requires water districts serving 10,000 or more residents to fluoridate tap water. That law went into effect Monday, although districts--including the City of Los Angeles--have some leeway until funding is found. Authorities will be allowed a grace period to locate funding to implement fluoridation, but eventually it will run from almost every tap in the state.

While fluoridation is seen as a positive development by most dentists, it will require residents to learn more about the chemical’s benefits and its potential hazards. Studies have shown that fluoride is safe and effective. Children who drink fluoridated water have 40% less tooth decay than children in non-fluoridated communities. It has been shown to strengthen tooth enamel, thus cutting the risk of decay.

On the other hand, young children can get too much fluoride--through water, supplements and toothpaste--which can result in stained or pitted teeth. “You don’t know [you’re consuming too much fluoride] until it’s too late to do anything about it,” says Dr. Donald F. Duperon, a UCLA professor of dentistry and expert on pediatric dentistry.

It is astonishing to many local dentists that Los Angeles remains the largest metropolitan area in the nation to be without fluoridation, so powerful are its benefits, says Dr. Eugene R. Casagrande, past president of the Los Angeles Dental Society and a longtime advocate of fluoridating local water supplies.

Sixty-two percent of Americans nationwide consume fluoridated water compared with 17% of Californians.

“The last time it was talked about in L.A. was over 20 years ago,” Casagrande says. “One of the major arguments was, it was a communist plot, that someone would poison us. And there have been concerns over toxicity and baldness, blindness, impotency, cancer--you name it, people feared [fluoride] would cause it.”

Now, with the safety issue settled by a number of scientific studies, the only compelling argument against fluoridation has been cost, he says. (Nevertheless there remains a small contingent of critics who oppose fluoridation as big-government intrusion.)

The City of Los Angeles was already closing in on passage of its own fluoridation measure prior to the state legislation. A City Council decision on when and how to implement citywide fluoridation is expected soon.

The City Council has instructed the Department of Water and Power to come up with ideas about how to fund fluoridation. The initial cost is estimated at $3.5 million, Casagrande says, with an additional $750,000 yearly estimated to maintain the system.

Still, fluoridation has a huge payoff by reducing the money taxpayers spend to treat the dental problems of indigent patients, Casagrande says.

“When you talk about fluoridation reducing decay levels by 40% to 60%, we shouldn’t even be talking about the cost,” he says. “We should be able to find the money somewhere.”

Thousands of poor children in Los Angeles never see a dentist and have extensive tooth decay, he says.

“Some kids don’t have the opportunity to go to the dentist every six months or to get fluoridated vitamin supplements or get fluoridated water delivered to their door or even get to use fluoridated toothpaste. Maybe some don’t even have a toothbrush,” Casagrande says.

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Public health officials in Los Angeles acknowledge that there is a large group of children who do not receive adequate dental care.

“The [tooth decay] rate is extremely high in the immigrant community, partly due to dietary habits,” Duperon says.

Compounding the problem, he adds, is the high cost of tooth decay. For example, very young children with decayed teeth must undergo surgery with general anesthesia to remove the teeth because they can’t tolerate local anesthetic.

“We’re taking teeth out of 2-year-olds. It costs $4,000 to $5,000 to put a 2-year-old under general anesthesia,” he says.

Even children who have the best dental care will benefit from fluoridation, Duperon says. Some quantity of fluoride is naturally present in ground water. But, in a series of studies he coauthored, Duperon found that the amount of natural fluoride present in drinking water varied considerably around the county, even from block to block.

The finding is important because dentists and pediatricians often prescribe fluoride vitamin supplements to their patients up until age 12--when all the permanent teeth have come in--if the local water supply is not fluoridated. Duperon’s study showed that, depending on where children live, they may already get enough fluoride.

“Unless the pediatrician analyzes their personal water supply, it’s impossible to know” if the child needs a fluoride supplement, he says. “We have such a mix of water sources. I can show you areas that are way above recommended levels and areas way below it. In Pasadena, we found changes from one street to the next because the water source changes.”

As a result, Duperon advises his colleagues not to prescribe fluoride supplements, and he has lobbied for fluoridation to standardize the levels in the water supply.

“It’s the only real solution,” he says. “It really makes a lot of sense to adjust the water because it is so hard for doctors to prescribe fluoride.”

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Children who get too much fluoride--usually through a combination of water high in fluoride and use of fluoridated toothpaste and fluoride supplements--can end up with mottled teeth, Duperon says. The first sign of a problem is white, chalklike spots on permanent teeth. These flecks can occur naturally but are also produced from too much fluoride. Children who live in fluoridated areas have about a 15% to 20% rate of flecks compared with a rate of 1% to 4% in areas without fluoridated water.

In severe cases, the white areas can turn brown and may even become pitted.

With a fluoridated water supply, it should be easy enough to avoid too much fluoride, Duperon says. Children will not need fluoride supplements, for example, unless their home is equipped with certain types of water filters that remove fluoride or they use non-fluoridated bottled water.

Moreover, dentists are working hard to teach children (and their parents) that only a tiny dot of toothpaste is necessary. Those TV commercials showing an inch-long, thick blob of toothpaste are misleading.

“We are teaching kids that a pea-shaped size or just a smear of toothpaste is enough,” Duperon says.

Studies show that young children swallow about 65% of toothpaste, he says, so it is critical for parents to use a minimal amount of toothpaste and teach the child to spit out excess toothpaste.