Adding fluoride to municipal drinking water has been controversial for years, with much debate over benefits (prevention of tooth decay) vs health concerns. Especially worrisome are recent studies finding that fluoride in drinking water may have negative effects on children's IQ, whether the fluoride exposure occurs during pregnancy or infancy.
Canadian researchers found that babies that drank formula mixed with fluoridated water had a lower IQ at age 3 to 4 than exclusively breastfed children. [Breastfeeding results in much lower levels of fluoride exposure, even when the mothers drink fluoridated tap water. This is because only limited amounts wind up in breast milk.]
As in the USA, some Canadian communities fluoridate their water while others don't. Exposure to increasing levels of fluoride in tap water (even at government recommended "optimal" levels) was associated with lower IQ scores (especially non-verbal intellectual abilities) in the children. The more the fluoride exposure, the bigger the effect. In other words, studies suggest that fluoride is a neurotoxicant in that it negatively affects the developing brain.
What to do? Try to breastfeed your baby for 6 months. But if using formula and your municipal water has added fluoride - try to mix the formula with unfluoridated bottled water, especially water in glass bottles (because plastic leaches and has more microplastics in it.
From Beyond Pesticides: Fluoride In Science News Again, This Time For Effects On Children's IQ
The findings of a new Canadian study will be cold comfort for parents whose babies and children have consumed baby formula constituted with fluoridated drinking water. Scheduled for January 2020 publication in Environment International, the research paper, titled “Fluoride exposure from infant formula and child IQ in a Canadian birth cohort,” reports a significant drop in IQ for such children, compared to formula-fed children living in non-fluoridated areas.
Researchers found that for each 0.5 mg/L increase in fluoride concentration in drinking water, there was an average decrease of 4.4 IQ points among preschool children who were formula-fed during their first six months of life. The scientists found no significant association between water fluoride concentration and IQ among exclusively breastfed children. Further, the paper’s findings suggest that exposure to fluoride, both pre- and postnatally, has greater impact on the development of non-verbal intelligence than on that of verbal intelligence. The co-authors note, “These findings suggest that using optimally fluoridated water (0.7 mg/L) to reconstitute infant formula may diminish the development of intellectual abilities in young children, particularly for non-verbal abilities.”
The research team, out of York University in Toronto, examined nearly 400 mother–child pairs. The subjects were part of the Maternal–Infant Research on Environmental Chemicals (MIREC) project, and hailed from six Canadian cities. Status of municipal drinking water in the resident cities of the subjects broke down to approximately 38% fluoridated and 62% non-fluoridated. When the children were between 30 and 48 months old, the mothers completed a questionnaire that asked about infant feeding (formula vs. breast milk vs. a combination of the two), and duration and timing of such feeding. Fluoride exposures were estimated via municipal water treatment data, and the feeding data for those subjects in the formula-fed (FF) and breastfed (BF) groups of subjects. IQ was then assessed via the Wechsler Preschool and Primary Scale of Intelligence-III.
The touted benefit of fluoride is the reduced incidence of dental caries once teeth have erupted and fluoride is topically applied. There is no benefit to use of fluoridated water for infants whose primary teeth have not erupted, and indeed, there would appear to be distinct downsides. Given this study’s results, the following facts take on greater significance: the researchers indicate that “formula-fed infants who reside in fluoridated areas have a 70-fold higher intake of fluoride than exclusively breastfed infants,” and “formula-fed infants also retain more fluoride than breastfed infants because infants have a limited capacity to excrete fluoride before renal function reaches its full capacity at about two years of age.”
In addition, the researchers noted that their estimate of fluoride intake among formula-fed infants (who live in communities with fluoridated water) may underestimate actual exposures because they did not include fluoride from other sources, such as infant formula itself, toothpastes, or foodstuffs. Thus, they say, the association between fluoride and lowered IQ scores among formula-fed infants may be even stronger than that in their analysis.
In reporting on an earlier study from the MIREC project, Beyond Pesticides wrote a bit about the history of fluoridation of water: “Before fluoride dental products were widely available, the U.S. Public Health Service introduced water fluoridation in the 1950s to reduce dental problems. In 2015, the U.S. lowered the optimal fluoride concentration from 0.7-1.2mg/L to 0.7mg/L after overexposure to fluoride caused 68% of adolescents to have enamel fluorosis — a disorder characterized by hypomineralization of tooth enamel appearing as discoloration and sometimes causing physical damage to the tooth.”
The pros and cons of fluoride in drinking water have been debated for decades. In the early 20th century, scientists began linking the few communities whose drinking water had high levels of naturally occurring fluoridation with lower levels of dental caries. In 1945, Grand Rapids, Michigan began adding fluoride to its water supply, and increasing numbers of municipalities followed suit as studies began to show lower rates of cavities in schoolchildren in fluoridated communities.
In 2015, the Cochrane Collaboration — a global, nonprofit, independent network of researchers and health care professionals known for rigorous scientific review of public health policy — published its findings, based on an analysis of 20 studies on water fluoridation. The collaborative group evaluated the effects of fluoride in water on the prevention of tooth decay and dental fluorosis; it found that, although fluoridation does tend to reduce dental caries in children, “no studies that aimed to determine the effectiveness of water fluoridation for preventing caries in adults met the review’s inclusion criteria.”
In addition, the report concluded that earlier (pre-1975) research studies on water fluoridation were deeply flawed, and therefore, their conclusions unreliable. It went on to say that “fluoride itself may be dangerous at high levels. Excessive fluoride causes fluorosis — changes in tooth enamel that range from barely noticeable white spots to staining and pitting. Fluoride can also become concentrated in bone — stimulating bone cell growth, altering the tissue’s structure, and weakening the skeleton. . . . Perhaps most worrisome is preliminary research in laboratory animals suggesting that high levels of fluoride may be toxic to brain and nerve cells. And human epidemiological studies have identified possible links to learning, memory, and cognition deficits.”
A 2012 meta-analysis published by Environmental Health Perspectives, and referenced in 2019 reporting by Beyond Pesticides, said that its results suggested that fluoride may be a developmental neurotoxicant that can impact neurodevelopment, and can do so at exposures much lower than those that can cause toxicity in adults. As previously noted, in 2015, the U.S. Department of Health and Human Services lowered the recommended level of fluoridation in drinking water because of concerns about dental fluorosis. At that time, Dr. Grandjean called this a “positive development,” but recommended that the level be reduced further because of potential health risks of aggregate fluoride exposure, including neurodevelopmental and thyroid anomalies.