27 August 2019. A Canadian research study was released a few days ago and was widely called “controversial”, as it linked water fluoridation to loss of IQ points in children. Some commentators stated that nothing could be decided on just a single study, others referred to the benefits of water fluoridation in preventing caries. Even the editor of the scientific journal, JAMA Pediatrics, decided – for the first time ever – that the article should be accompanied by an apology for releasing such a controversial study. Yet, in the journal’s podcast, the editor recommended that pregnant women living in fluoridated communities should drink bottled water rather than the piped water with added fluoride.
The brouhaha is perhaps not surprising, as it refers to a long-standing tradition of feeding fluoride to huge populations to control caries – an intervention that is considered a cornerstone of modern prevention. Clearly, important authorities have taken a stand and decided to campaign for addition of fluoride to people’s drinking water, and they will not easily be convinced that fluoride is not all that good, after all. In fact, many countries have decided against fluoridation. Interestingly, the caries incidence in those countries is not any worse than it is in the U.S., where about two-thirds of the population is fluoridated.
Back to the Canadian study. Between 2008 and 2011, more than two thousand pregnant women were recruited into the Maternal-Infant Research on Environmental Chemicals (MIREC) cohort from major Canadian cities. Their children were examined with an IQ test at age 3-4 years, and the mother’s urine samples were located in the freezers from all three semesters of pregnancy, so that data could be analyzed for 526 mother-child pairs. The results were adjusted for exposures to other neurotoxicants and relevant covariates, such as sex, age at examination, and maternal exposure to indirect smoking, race, and education. The results showed that an increase of 1 mg/L of fluoride in water and an increase of 1 mg/day of total fluoride intake were associated with an IQ loss of 5.3 points and 3.66 points, respectively, for both boys and girls. Further, an increase in urine-fluoride of 1 mg/L was associated with a statistically significant loss in IQ of 4.49 points in boys, though not in girls. The latter finding may suggest that girls are less vulnerable than the boys, and they did have higher IQs.
Contrary to some of the news reports, this study did not appear out of the blue. The results are very similar to a study of similar design that was carried out in Mexico and published in 2017. Also, numerous studies have been carried out in countries such as China that show lower IQs in children exposed to elevated amounts if fluoride – even small elevations that would be considered safe by the U.S. EPA. In fact, the debate that happened on previous occasions is similar to what is happening now: Fluoridation is known to be safe and beneficial, and a single study does not change much. But it is not a single study any more. And fluoridation does not seem to be all that beneficial.
There is one new aspect, or one that has not received much attention until now. The Canadian researchers had obtained information on beverage intakes during pregnancy, including tea, as especially black tea can add substantially to the daily fluoride intake. The new findings suggest that, to control fluoride intakes, one has to limit tea consumption.
Excess fluoride is toxic, and it was known decades ago that too much fluoride could cause neurological symptoms. In certain parts of the world, especially in China, there is much fluoride in the soil that dissolves in the groundwater. In small amounts, the fluoride causes mottled teeth. In greater amounts, the result is a crippling bone disease called skeletal fluorosis. The U.S. Environmental Protection Agency decided many years ago that it needed to protect people against this bone disease and ignored any other risks. The time has come for health agencies in the U.S. and elsewhere to revisit the fluoride regulations and make it a priority to protect the brains of the next generation.