The Tacoma-Pierce County Board of Health will consider a proposal Wednesday to mandate water fluoridation for nearly a quarter of a million county residents.

The board will hear public comment on the proposal and could vote on it – though it’s also possible the decision will be postponed.

It’s unusual for a health board to take on the issue, which is often put to a public vote. But health department Director Federico Cruz-Uribe contends fluoridation is vital to stem an epidemic of tooth decay, particularly among low-income children. He insists the health board has the authority to require fluoridation, just as it would adopt rules pertaining to any other public health issue.

However, water districts and some towns oppose the mandate – and some have vowed to challenge the board in court.

Here are some questions and answers on the proposal and fluoridation in general:

Q: What areas of Pierce County are already fluoridated?

A: Tacoma, Fircrest, University Place, McChord Air Force Base, Fort Lewis, and communities located along Tacoma’s pipeline from the Green River. Seattle is also fluoridated.

Q: Is unfluoridated water available to people who live in fluoridated areas?

A: Yes. Tacoma has an unfluoridated, unchlorinated tap on a well at South 74th and Cedar streets. The water is free. Residents bring their own containers. Usage is about 170 gallons a day.

Q: Who would be required to fluoridate under the health department proposal?

A: All water systems that serve more than 5,000 people. That includes 14 water districts and 238,000 people. The water systems are: Lakewood, Puyallup, Bonney Lake, Parkland Light & Water, Spanaway Water Co., Firgrove Mutual Inc., Summit Water & Supply Co., Southwood Water System, Fruitland Mutual Water Co., Mountain View-Edgewood Water Co., City of Sumner, City of Milton, Sound Water and Town of Steilacoom.

Q: How much fluoride would be added to the water?

A: One part per million is the recommended concentration. Fluoride toothpastes contain about 1,000-1,500 ppm.

Q: How much would fluoridation cost and who would pay for it?

A: Estimates range between $1 million and $2.8 million. The Washington Dental Services Foundation may provide some grant money to help communities pay for fluoridation equipment. Water systems would bear all other costs, passing them along to customers.

Q: How prevalent is tooth decay in Pierce County?

A: Based on examinations by dental hygienists, the health department estimates about 46 percent of kids who live in unfluoridated areas have cavities, compared with 39 percent of those who live in fluoridated areas. For low-income children, 50 percent of those in unfluoridated areas had cavities, compared with 35 percent in fluoridated areas.

However, the data are not unequivocal. One set showed slightly higher primary tooth decay rates in fluoridated areas, and 59 percent of kids examined in Tacoma had cavities – even though the water supply has been fluoridated more than 10 years.

Q: Is fluoridated water effective at preventing tooth decay?

A: When it was first introduced in the 1940s and ’50s, fluoridation reduced cavities 40-60 percent. In recent years, the benefits appear to have dropped to 15-20 percent decay rate reductions. Some studies suggest that decay rates are declining equally in fluoridated and unfluoridated areas, possibly because of the widespread presence of fluoride in other substances, such as toothpaste.

Q: Does fluoride only benefit children?

A: No. It also reduces decay rates in adults, including the elderly.

Q: What types of cavities does fluoride prevent?

A: Fluoride is most effective against cavities on flat surfaces of teeth. It is less effective against decay on the pits and fissures of chewing surfaces – which is the most common type of tooth decay in children.

Q: How does fluoride work?

A: The most recent research concludes that fluoride works mainly on the surface of teeth, reducing the amount of cavity-causing bacteria, neutralizing bacterial acid and attracting calcium, which repairs decay and strengthens tooth enamel.

Q: Isn’t brushing twice a day with fluoride toothpaste enough to protect against decay?

A: Regular, lifetime use of fluoride toothpaste can provide benefits similar to drinking fluoridated water. However, the benefits of combined use of fluoridated water and fluoride toothpaste are even greater, says the U.S. Centers for Disease Control and Prevention.

Q: Is fluoride linked to cancer?

A: More than 50 epidemiologic studies in several countries failed to show any association between fluoride and the risk of cancer, and several independent reviews of the data conclude there is no evidence of a link.

One U.S. study reported higher cancer death rates in large, fluoridated cities. The National Cancer Institute and other researchers have refuted that study, arguing that it didn’t take age, gender and level of industrialization into account.

Two studies in the early 1990s reported malignant bone tumors linked with higher fluoride consumption in one of eight group of rats. Some federal scientists claim the significance of the study was downplayed by government agencies. The U.S. Public Health Service and the National Cancer Institute reviewed the research and both concluded there is no association between fluoride and increased cancer risk.

Q: Does fluoride increase the risk of hip fractures?

A: A 1992 study reported a small increase in hip fractures in areas with fluoridated water supplies. Two subsequent studies found no such link. Other studies have suggested that fluoride reduces the risk of hip fractures.

Q: Does fluoride have other harmful health effects?

A: Fluoride opponents cite a handful of studies that have suggested a link between fluoride and Alzheimer’s disease, allergies, immune system disruption, Downs Syndrome and neurotoxic effects.

Major scientific organizations have cited flaws in all of those studies and concluded that none has merit.

Q: Who supports fluoridation?

A: More than 90 national and international health and social organizations, including: the World Health Organization, CDC, U.S. surgeon general, Institute of Medicine, National Academy of Sciences, National Dental Association, American Cancer Society, Alzheimer’s Association.

Q: Who opposes fluoridation?

A: Citizens for Safe Drinking Water; The Sierra Club (opposes mandatory fluoridation); Washington Public Interest Research Group; Washington Toxics Coalition; National Treasury Employees Union Chapter 280, representing some scientists at EPA’s Washington headquarters.

Q: Where can I find more information?

A: Extensive information on fluoridation is available online from:

* The American Dental Society: www.ada.org/public/topics/ fluoride/fluoride.html.
* The Centers for Disease Control and Prevention: www.cdc.gov/ nccdphp/oh/fl-home.htm.
* U.S. Public Health Service review of fluoride’s benefits and risk is available at: www.health.gov/environment/ReviewofFluoride.
* The surgeon general’s 2000 report on oral health is available at: www.cdc.gov/nccdphp/oh/sgr2000-05.htm.
* Information from fluoride critics is available at: www.fluoridealert.org.

Sources: American Dental Association, American Academy of Family Physicians, Centers for Disease Control and Prevention, Fluoride Alert.org, U.S. surgeon general, U.S. Public Health Service.