By Mary Otto
In an effort to get a clearer view of how rhetoric has shaped the media coverage of community water fluoridation over the years, researchers looked at more than five decades worth of news coverage surrounding 11 community water fluoridation (CWF) referenda in three U.S. cities: Portland, Oregon, Wichita, Kansas and San Antonio, Texas.
They analyzed the language used in the news articles and compared it with the rhetoric used by fluoridation proponents such as the American Dental Association (ADA) and opponents such as the Fluoride Action Network (FAN).
They found that opponents’ pseudoscientific claims about fluoride’s risks to children reflected in news stories.
They also found signs of “balance bias” in the media coverage which they described as a tendency by reporters to assign equal weight to opposing views “regardless of the strength of evidence supporting those views.”
In their study, published in April 2018 in the Journal of the American Dental Association, the researchers made a plea for better-informed journalism.
“A journalist covering an election with a clear understanding of the differing scientific merit of each side will be able to conduct more investigative studies as opposed to reporting on logically fallacious argumentum ad passiones arguments against CWF,” they wrote.
In their campaigns, fluoride opponents often cite studies that link fluoride to adverse health outcomes such as lower IQ.
A previous tip sheet on the fluoride debate in Kansas explored this tactic and how it played out in the days leading up to a 2012 vote on water fluoridation in Wichita.
Members of Wichitans Opposed to Fluoridation cited a group of studies reviewed by Harvard scientists that indicated that high levels of fluoride could be linked to lower IQs among schoolchildren.
But in this case, a local newspaper investigated the claims.
The Harvard scientists told The Wichita Eagle that the data was not particularly applicable in the United States because it came from foreign sources where fluoride levels were many times higher than they are in American tap water.
“The Harvard scientists did not gather the original data for the paper they published in July, titled ‘Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis,’ wrote Eagle reporter Dion Lefler:
“The Harvard paper was a compilation of 27 other studies, 25 of which were done in China.
“On average, children with higher fluoride exposure showed poorer performance on IQ tests,” the Harvard researchers wrote. “Fluoride released into the ground water in China in some cases greatly exceeded levels that are typical in the U.S. In general, complete information was not available on these 27 studies, and some limitations were identified.”
“One of the Chinese studies that has been translated into English, “Research on the intellectual abilities of 6- 14- year-old students in an area with endemic fluoride poisoning,” gave a glimpse of what the study limitations are.
“The students in the study were drinking well water containing seven parts per million of fluoride – 10 times the amount proposed for Wichita water.
“The study compared children in a control group with those whose water had high levels of fluoride.
“The children in the control group were drinking water with up to .8 parts per million of fluoride, a slightly higher level than .7 parts per million that will be in Wichita water if the ballot issue passes.
“The Chinese researchers found children using the high-fluoride water had IQs about a point lower than the control group,” Lefler wrote. “But the researchers also found the IQ differential didn’t appear to last to adulthood.”
In the November 2012 election, however, Wichita voters rejected fluoridated water as they did in 1964 and 1978.
Researchers around the world have continued to explore fluoridation and to examine claims of possible adverse effects such as neurotoxicity and lower IQ.
One such study, undertaken in response to such concerns, a team of environmental scientists, and supported by the National Toxicology Program‘s Division of the National Institute of Environmental Health Sciences was published in February 2018.
Researchers reported “no exposure related differences in motor, sensory or learning memory performance” for any of nine different tests performed by rats that had consumed water and food with different concentrations of fluoride.
The only side effect identified in the study was inflammation of the prostate gland, found at fluoride exposures five times higher than humans would experience drinking fluoridated water, they wrote.
Meanwhile, research continues to show the benefits of fluoride.
Children living in counties with fluoridated water have significantly less tooth decay than those living in counties that lack water fluoridation programs, a newly-published large-scale study has concluded.
While reduced decay rates were most notable in the primary teeth of children living in fluoridated counties, community water fluoridation (CWF) was also credited with providing a meaningful level of protection to the permanent teeth of children and adolescents.
Optimally fluoridated water is available to approximately 75 percent of the U.S. population, according to the Centers for Disease Control and Prevention.
The agency monitors federal and state efforts to increase access to fluoridated water to 79.6 percent nationwide, in keeping with oral health goals set forth in the federal government’s Healthy People 2020 initiative.
To learn more about fluoridation efforts over the years, this paper from the Centers for Disease Control and Prevention offers a useful history of community water fluoridation and outlines the science behind the effectiveness of fluoridation in preventing tooth decay.
And this 2015 paper by then-Surgeon General Vivek Murthy, written to commemorate the 70th anniversary of Community Water Fluoridation programs explains how the effort has evolved and changed over the years.
Fluoride is the ionic form of the element fluorine, among the most abundant elements in the Earth’s crust. Fluoride is present in most of the Earth’s water as well, though not always at levels determined by research as optimal to inhibit tooth decay.
Because the fluoride ion is negatively charged, it has an affinity for positive ions such as calcium found in calcified tissues including teeth.
When fluoride is ingested in water or applied to the teeth in toothpaste or other products, it becomes concentrated in saliva and in the matrix of plaque that coats the enamel of the teeth.
Each time food is eaten, decay-causing bacteria metabolize carbohydrates and produce acids that strip calcium and phosphate from the teeth. But when fluoride is present in saliva and plaque, its ions join with available calcium and phosphate, forming a new mineral, fluorapetite. Through this remineralization process, fluoride strengthens the teeth and helps prevent tooth decay.
Community water fluoridation programs provide for the controlled adjustment of fluoride to bring it to the level that research has determined is optimal for fighting tooth decay while not so high as to contribute to fluorosis, a condition that causes light mottling and in rare cases severe pitting of tooth enamel of the teeth.
The fluoride level long regarded by health officials as optimal for cavity prevention was set at a range of 0.7 milligrams to 1.2 milligrams per liter of water. But in January 2011, officials at the U.S. Department of Health and Human Services, while continuing to stress the benefits of fluoride, proposed that the recommended level of fluoride in drinking water be set at the lowest end of that range. They noted that the lower standard reflected research into changing water consumption patterns over time. In addition, they observed that Americans are now getting fluoride from a range of sources that did not exist in the 1940s when community water fluoridation programs first got underway.
On April 27, 2015, public health officials updated their recommendation for the “optimal” level of fluoride in drinking water nationwide. The updated standard, 0.7 milligrams of fluoride per liter of water, was announced by the U.S. Department of Human Services.
The Community Preventive Service Task Force is among the U.S. bodies of experts that has reviewed the potential of community water fluoridation to contribute to fluorosis.
“The data for fluorosis, both from the existing systematic review and newly identified studies, show a clear dose response relationship with fluoride in drinking water. Fluorosis is an enamel defect ranging in severity from barely noticeable white spots in mild forms to staining and pitting in more severe forms. The critical period for the development of fluorosis is from birth to 8 years. Prevalence of detectable dental fluorosis is around 40 percent in optimally fluoridated areas.
The majority of these cases are mild and difficult to see except by trained dental health professionals, and are not considered to be of aesthetic concern. There is no evidence that CWF results in severe fluorosis.
Although bone fractures and skeletal fluorosis have been associated with lifetime exposure to higher naturally-occurring fluoride concentrations (e.g. 4 mg/L), no association has been observed at levels used for CWF. The broader literature speculates about harms associated with higher levels of fluoride in water (e.g., cancer, lowered intelligence, endocrine dysfunction). Research evidence, however, does not demonstrate that CWF results in any unwanted health effects other than dental fluorosis. While harms have been proposed, most have no biological plausibility or insufficient evidence to draw conclusions.”
