The idea that water fluoridation is a vast Communist conspiracy aimed at undermining public health is largely a thing of the past. However, the facts surrounding the continued use of fluoride in public drinking water seem to vary greatly depending on whom you talk to.

According to the Center for Disease Control, 4.7 million residents across the commonwealth receive fluoridated water. That is 70.4 percent of all residents on community water systems.

Ria Convery, of the Massachusetts Water Resource Authority, said the MWRA — which provides full or partial water service to many communities north of Boston — has added fluoride to water for more than 30 years. It maintains a target fluoride level of 1.0 part per million in drinking water as recommended by the CDC.

“The strong position taken by the CDC, one of the world’s leading public health institutions, is important to understanding MWRA’s addition of fluoride to reduce tooth decay and promote community public health,” Convery said.

The state’s Department of Public Health takes a similar stand.

In a statement issued in 2010, which, according to spokesman Scott Zoback is still valid today, DPH calls fluoridation a safe, cost-effective and practical way to prevent tooth decay and argues that it benefits all residents regardless of age or income status.

“There is no public safety concern about fluoridation in Massachusetts,” the statement from Zoback reads. “DPH continues to support the benefits of community water fluoridation for dental health.”

Yet there is a growing movement that believes to fluoridate or not to fluoridate should be an individual choice, which raises the inevitable question: Does the good outweigh any potential bad when it comes to fluoridated water?

Magic or mayhem

Communities in the United States have been fluoridating water systems since the mid-1940s, and fluoridation became an official policy of the U.S. Public Health Service by 1951. By 2006, nearly 70 percent of the country’s population serviced by public water systems (and nearly 62 percent overall) were receiving fluoridated water.

“When this started in 1945, the belief was you had to swallow fluoride so the teeth below the gums wouldn’t decay,” said Carol Kopf, of the Fluoride Action Network, or FAN. “They thought fluoride was a magic bullet.”

FAN’s mission is to “broaden awareness about the toxicity of fluoride compounds among citizens, scientists, and policymakers alike.” Kopf and many others in Massachusetts and across the country now believe that, not only is fluoride not the answer to perfect teeth, it’s harmful in other ways.

Topsfield resident Jeffy Demeter was studying nutrition when she stumbled on the subject of water fluoridation several years ago. She said she learned that a great number of people suffer from iodine deficiencies, which is a side effect of over-fluoridation. Further research showed that too much fluoride is also potentially harmful for infants and the elderly.

Another concern is the risk of dental fluorosis, which leaves white, almost lacy markings on tooth enamel. Kopf, who has been fighting mandated water fluoridation since the 1980s, said it comes from over-fluoridation and estimates that 40 percent of American teenagers have those markings.

Demeter calls fluoride a chemical that if taken in too large a dose by a small child could prove fatal.

“That’s really just a dramatic situation to prove a point and it’s never happened that I know of, but it could,” she said, adding that is why there are warning labels on items such as toothpaste that contain fluoride.

The DPH instead calls fluoride a natural occurring mineral that when added to water can prevent tooth decay by as much as 60 percent in baby teeth, and by as much as 35 percent in adult or permanent teeth.

“People say, ‘I grew up with it, it’s not harmful,’ but I don’t think people realize the effect,” Demeter said. “The effects are cumulative, they build up and it affects everyone differently.”

Topsfield has been adding fluoride to its drinking water, which comes from the Ipswich River, since 1953, about two years before fluoridated toothpaste was introduced, Demeter said. At the time it could be argued that public water was for many people their only exposure to fluoride, but Demeter said that is no longer true. Fluoride is now readily found in most toothpastes and dozens of mouthwashes and even some bottled water, and that much exposure, over a lifetime, can add up to over-fluoridation.

Kopf also argues researchers have since discovered fluoride is only truly effective when used topically, not by drinking. Reports from the CDC counter that notion, stating, “even today, with other available sources of fluoride, studies show that water fluoridation reduces tooth decay by about 25 percent over a person’s lifetime.”

The DPH also states fluoride from fluoridated water is incorporated into the structure of growing teeth, providing strength and added protection.

State studies aside, last summer Demeter took her concerns to the people when she launched a petition for a special Town Meeting. The single warrant article asked Topsfield residents to vote on whether they wanted to continue the practice of adding fluoride to the water, but it never made it to the floor.

Demeter said the Finance Committee instead proposed forming a committee to look at the issue. She is hoping the committee will have a report ready for this year’s annual Town Meeting in May.

Topsfield isn’t the only community to potentially face a town-wide vote on the issue. Demeter said Newburyport, Rockport and Gloucester are all looking at ballot questions and in 2011, Amesbury voters opted out of water fluoridation when 55 percent of residents voted to ditch the 44-year-old practice.

The benefits

According to the DPH Office of Oral Health, the benefits of water fluoridation are clear. They include “fewer and less severe cavities, decreased need for fillings and tooth extractions, and reduced pain associated with tooth decay.”

Convery said a CDC report, “Ten Great Public Health Achievements — United States 1900-1999,” pinpoints fluoridation of public water to reduce tooth decay as one of the leading public health achievements of the last century.

Demeter has argued the Environmental Protection Agency never approved fluoridation, but Convery said the EPA sets fluoride standards to guard drinking water safety.

“I should note that the EPA is currently evaluating [changing] the recommended dosage from 1.0 parts per million to 0.7,” Convery added. “When and if that change occurs we will lower our target as well.”

The CDC calls water fluoridation the least expensive way to deliver the benefits of fluoride to all residents of a given community. It estimates that for larger communities of 20,000 or more, it costs about 50 cents per person to fluoridate the water and that every $1 invested in the preventative measure translates to about $38 in savings in dental treatment costs.

Demeter said the debate over fluoridated water essentially boils down to one issue for her.

“I think it should be a choice,” she said. “The cause of dental decay is not a lack of fluoride and if you don’t have fluoride in your water, it’s not a communicable disease, you can get supplements.”

Convery was as solid in her support as Demeter was in her opposition.

“We are aware that a number of people across the country are raising questions about fluoride in drinking water,” Convery said. “MWRA intends to keep an open-minded view on any matters of technical competency and we will pay close attention to competing viewpoints. But it is doubtful that MWRA’s position will change so long as the CDC, MDPH and others continue to support fluoridation and its benefits.”