A good portion of residents in southwestern Riverside County can look forward to fewer cavities and healthier teeth, water officials say.

Metropolitan Water District of Southern California on Monday began adding fluoride to its water supply at a Riverside treatment plant that provides water to most of western Riverside County. This is the first of the district’s five plants to supplement the trace amounts of fluoride that are naturally in the water.

Customers won’t notice a difference in the water, MWD officials say.

The move is bringing the system up to par, the MWD said. Nationally, 43 of the 50 largest cities in the country already fluoridate their water and 67 percent of the population drinks fluoridated water, said Tim Collins, chairman of the California Dental Association’s Fluoridation Advisory Council. The $5.5 million chemical injection system, paid for with a grant from a private health foundation, will raise the level of fluoride from 0.1 to 0.4 part per million to the recommended range of 0.7 to 0.8 part per million, water officials said.

‘A Significant Step’

“This is a significant step toward catching up with the rest of the nation,” Collins said. “… The most important thing the community can do to ensure the oral health of residents is to fluoridate the water supply.”

California’s water districts and city utilities with more than 10,000 connections have been required to add fluoride since a 1995 state law went into effect. MWD, as a wholesaler, was not part of that.

But MWD’s board approved adding fluoride after health officers from the six Southern California counties it serves asked MWD to do so, said district spokesman Bob Muir.

The additional fluoride will help reduce tooth decay by 20 percent to 40 percent, Collins said.

But not everyone is in favor of adding fluoride.

Oakland-based Environmental Working Group petitioned MWD to reconsider. The group’s concerns follow emerging research about possible health risks since MWD approved the move in 2003, said Bill Walker, vice president of the environmental group.

Concerns

“The research is emerging, but it’s enough that makes us concerned,” Walker said. “We think with all this new evidence, Metropolitan Water District should wait.”

Walker said threats include fluorosis, a pitting and staining of the teeth, and the possibility that ingesting fluoride as a child might put teenage boys at greater risk of bone cancer. It isn’t that fluoride itself is harmful, but it should be applied rather than ingested, Walker said.

“It’s like drinking a bottle of sunscreen,” he said.

In the Inland area, the level of fluoride in the water will vary in different areas because some cities and water agencies blend Metropolitan’s water with their own supply, others do not use MWD water, and some water, including that in Riverside, already has enough natural fluoride that none has to be added.

The fluoridated tap water should not be used to mix powdered infant formula, which already contains fluoride, Collins said. Physicians, dentists and pharmacists in MWD’s service area have also been told to recommend that patients suspend fluoride supplements for the next year while the fluoridation system is established, Collins said.

The added cost will be $1 per family per year, Muir said.

The American Dental Association estimates that for every $1 spent, fluoridated water saves $38 in dental bills.

“Fluoride is conditioner for the tooth,” said Mary Hayes, a Chicago pediatric dentist and a spokeswoman for the American Dental Association. “If you choose not to use fluoridated water, you are removing that chance for prevention and success.”

MWD adds fluoride

Monday: Henry J. Mills water treatment plant in Riverside, which provides water to southwest Riverside County

Nov. 12: F.E. Weymouth plant in La Verne, which serves Los Angeles County

Nov. 19: Robert B. Diemer plant in Yorba Linda, which serves Orange County

Nov. 26: Joseph P. Jensen plant in Granada Hills, which serves Los Angeles and Ventura counties

Dec. 3: Robert A. Skinner plant near Temecula, which serves southwest Riverside and San Diego counties