The benefits of adding fluoride to our drinking water may have weakened over time. In a new review of the evidence, scientists found that while water fluoridation may slightly reduce the risk of cavities in young children, its overall effect is probably less than it was 50 years ago, before fluoride became widely available in toothpaste.
Beginning in the 1950s, states and cities across the US began adding fluoride to drinking water, following research showing that fluoride could prevent tooth decay, especially in children. Today, water fluoridation is used in many countries, and has been hailed as one of the most effective public health interventions in modern times. But there has long been a debate about the direct benefits of water fluoridation, and whether they may outweigh the potential risks. Researchers with the Cochrane Library, a research organization widely respected for its extensive reviews of clinical trial data related to important public health topics, have now decided to take a closer look at fluoridation using the latest gold standard evidence available.
Researchers recently reviewed 22 studies in community water systems, making sure to distinguish between studies conducted before and after 1975, when fluoride began to be widely added to toothpaste products. They focused on a specific question: whether the introduction or loss of these programs affected people’s risk of cavities. Overall, they found that today’s systems can still lead to less decay in children’s teeth, and more children who don’t decay completely. But they also found that the benefits of water fluoridation are probably less than they were before 1975.
“Current evidence using different research methods shows that the benefits of fluoridating water have diminished in recent decades,” said review author Tanya Walsh, professor of health care evaluation at the University of Manchester, in a statement from the Cochrane Library.
The new studies in the review were conducted in high-income countries, the researchers note. People in many parts of the world still have very high rates of tooth decay and limited access to fluoride toothpaste or other preventative treatments. Therefore, new water fluoridation systems in these areas may have a positive impact on the dental health of residents. But the researchers add that much has changed in the last 50 years, and that the risks and benefits of these programs should be closely evaluated from now on, especially in deciding whether to start new ones in areas where there may be less need.
“Inequalities in oral health are an urgent public health issue that requires action. Water fluoridation is only one option and is not very suitable for all people,” said Walsh.
A previous Cochrane review found that these programs may increase the risk of dental fluorosis in young children—a condition caused by excessive exposure to fluoride that can cause tooth wear. Another recent study also found a possible link between fluoride exposure and poorer kidney health in adolescents, as well as evidence that increased fluoride exposure in utero is associated with a greater risk of children developing neurobehavioral problems by age 3. On the other hand, there are many less-founded beliefs about the harms of fluoridation, such as the idea that fluoride can increase the risk of cancer.
The key takeaway from all of this research and debate should be that science and the world around us are constantly evolving. At the best of times, we are able to adapt to new evidence and act accordingly. It is certainly possible that water fluoridation will cease to be as useful as a public health measure as it once was. But that doesn’t mean it doesn’t place importance on the past.
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