New Cochrane Review Finds Water Fluoridation Has Minimal Effect on Dental Health

Adding fluoride to drinking water provides very limited dental benefits, according to an updated Cochrane Review published Friday.

by Brenda Baletti, Ph.D.

Adding fluoride to drinking water provides very limited dental benefits, especially compared with 50 years ago, according to an updated Cochrane Review published today.

The review follows less than two weeks after a California federal judge ruled water fluoridation poses an “unreasonable risk” of reduced IQ in children and must be regulated by the Environmental Protection Agency (EPA).

It also comes as some U.S. cities and towns have moved to pause or stop fluoridating their water in response to the verdict, signaling that fluoridating water, a long-term and largely unquestioned practice in the U.S., is facing heightened scrutiny.

To determine if water fluoridation leads to reduced rates of tooth decay, researchers from the University of Manchester and other U.K. universities reviewed 157 studies comparing communities that fluoridated their water to those that don’t.

They concluded that contemporary evidence shows community water fluoridation may lead to a very small reduction in cavities in children’s baby teeth over time. Fluoride in water reduced tooth decay only by about one-quarter of one tooth, they found, and even that conclusion was made with “low certainty.”

“Adding fluoride to water may slightly increase the number of children who have no tooth decay in either their baby teeth or permanent teeth,” the study authors wrote. “However, these results also included the possibility of little or no difference in tooth decay.”

They said studies conducted in 1975 or before showed a larger benefit of water fluoridation on tooth decay, CNN reported — a reduction of about one less cavity in baby teeth. However, those findings no longer apply to populations today who have better baseline dental health and exposure to other sources of fluoride, like toothpaste, they said.

The findings also confirm recent observational studies, including the LOTUS Study, which found only a 2% reduction in cavities among people living in fluoridated areas in England.

The conclusions — taken together with recent scientific research and the federal court decision — raise serious questions about the practice of community water fluoridation.

“When interpreting the evidence, it is important to think about the wider context and how society and health have changed over time,” said co-author Anne-Marie Glenny, professor of Health Sciences Research at the University of Manchester.

“Given that the benefit has reduced over time, before introducing a new fluoridation scheme, careful thought needs to be given to costs, acceptability, feasibility and ongoing monitoring,” said co-author Lucy O’Malley, Ph.D., senior lecturer in Health Services Research at the University of Manchester.

Public health agencies, professional organizations like the American Academy of Pediatrics (AAP) and lobbying organizations like the American Dental Association (ADA) have ignored or opposed the growing body of research showing fluoride’s adverse health effects, insisting the benefits of water fluoridation are unquestionable.

They maintain water fluoridation is a safe and effective strategy for oral health.

“I find it incredibly irresponsible that agencies like the CDC [Centers for Disease Control and Prevention], American Dental Association and the American Academy of Pediatrics have lauded and promoted this harmful practice of fluoridation for far too long,” integrative dentist Dr. Griffin Cole told The Defender.

Cole said that given the known neurotoxic effects of fluoride, there was never any justification for fluoridating water. He said:

“It is accurate to say we are all exposed to so many other sources of fluoride that continuing to add it to our water supply is now not necessary, but it’s disingenuous and unconscionable to say the statistically insignificant effect on tooth decay was worth poisoning millions of Americans and children’s brains for nearly 80 years.”

In last week’s 80-page federal court decision, U.S. District Judge Edward Chen evaluated and summarized the extensive scientific data presented at trial demonstrating that fluoride has neurotoxic effects on the developing brains of fetuses and children.

According to Chen, the “optimal level” of water fluoridation currently used in the U.S., which is 0.7 milligrams per liter, is too close to the known level at which fluoride poses a neurotoxic risk and may itself be neurotoxic.

Research published in JAMA Network Open in May shows that children born to women exposed during pregnancy to fluoridated drinking water at optimal levels were more likely to have neurobehavioural problems.

The authors of the Cochrane study also found insufficient evidence to show that water fluoridation reduces oral health inequalities, which is one of the key claims supporters like the ADA used to justify the practice.

Last week, the ADA and the AAP confirmed they remain staunch supporters of water fluoridation.

ADA President Linda J. Edgar said in a statement that scientific evidence shows community water fluoridation reduced cavities by 25% — a significantly higher claim than found in the Cochrane review.  Dr. Charlotte W. Lewis, a member of the AAP Section on Oral Health, said water fluoridation is “a public health policy based on a solid foundation of evidence.”

Neither organization immediately responded to The Defender’s request for comment.

The CDC, which has long advocated for water fluoridation as a “cornerstone strategy” for limiting tooth decay, and the EPA, which has refused to regulate it, also did not respond to The Defender’s request for comment on the study.

Over 200 million Americans are currently exposed to fluoridated water on a daily basis.