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.
An event causing early concern about fluoridation was a 1990 animal experiment that appeared to show equivocal (uncertain) evidence, in male rats, that fluoridated water fed to them yielded a high number of cases of osteosarcoma, a type of bone cancer. Subsequent studies and reports, in 1991, 1993, 1999, and 2011, have all underscored the conclusion that none of the data demonstrated an association between fluoridated drinking water and cancer.
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.”
Philippe Grandjean, adjunct professor of environmental health at the Harvard T.H. Chan School of Public Health, commented on the Cochrane Collaboration report, saying “We should recognize that fluoride has beneficial effects on dental development and protection against cavities. But do we need to add it to drinking water so it gets into the bloodstream and potentially into the brain? To answer this, we must establish three research priorities.” Those are: (1) ensure that fluoridation is done to no greater than the necessary level for dental medical purposes; (2) ensure that fluoridation doesn’t increase risks of harmful health outcomes; especially needed is basic animal research that would identify how fluoride may be toxic to developing brains; and (3) identify populations that may be very vulnerable to drinking water fluoridation, e.g., formula-fed babies or patients undergoing dialysis, so that their water can come from a lower-fluoride source. The subject Canadian study’s results address the third of those priorities.
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.
Beyond Pesticides has covered a related fluoride issue in its advocacy against food uses of the insecticide sulfuryl fluoride (typically, for post-harvest fumigation), a neurotoxic compound often used against termites, bedbugs, roaches, and rodents that is also associated with reduced IQ in children. Use of this pesticide was first permitted in food production in 2004. Advocates have charged that, apart from the risks of acute exposures, in combination with fluoride use in water fluoridation, its food uses and subsequent exposure potential create unacceptable risks under EPA and National Academy of Sciences (NAS) scientific determinations.
After a 2006 petition by Beyond Pesticides, Fluoride Action Network, and Environmental Working Group, in 2011 the Environmental Protection Agency (EPA) proposed to eliminate agriculture and food related applications of the compound, and to phase the elimination over a three-year period. The agency agreed that under the 1996 Food Quality Protection Act, it should calculate the aggregate exposure risks associated with fluoride use in food and water.” As Beyond Pesticides reported at that time: “The agency plans to cancel all allowable pesticide residue levels (tolerances) for the chemical, finding that, when residues on food pare combined with fluoridated drinking water and toothpaste, public exposure levels are too high. Under the Federal Food, Drug, and Cosmetic Act (FFDCA), EPA is required to ensure that pesticides it has registered for use cannot combine with non-food sources of the same substance to result in unsafe levels of exposure for that chemical.” After much lobbying and conference amendments, the 2014 Farm Bill was signed — including language instructing the EPA administrator to exclude non-pesticidal (all water fluoridation) sources of fluoride when determining aggregate risk exposure to sulfuryl fluoride.
The use of this compound continues. There are multiple avenues to avoidance of excess-fluoride risks, including: learning about local fluoridation practices; practicing and/or advocating for breastfeeding for the first six months (or more) of an infant’s life, especially in fluoridated communities; being mindful of exposures through dental practices; and choosing organic food whenever possible. Beyond opting for organic food options to avoid additional dietary exposure to sulfuryl fluoride, consumers can find information on alternative ways to deal with pest problems and avoid sulfuryl fluoride (as well as other pesticides) here. For options in dealing with specific pest problems, see Beyond Pesticides’ website pages on bedbugs, rodents, termites, and roaches.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.