Fluoride exposure from infant formula and child IQ in a Canadian birth cohort

Till, Christine; Green, Rivka; Flora, David B.; Hornung, Richard; Martínez-Mier, E. Ángeles; Blazer, M; Farmus, Linda; Ayotte, Pierre; Muckle, Gina; Lanphear, Bruce P.

doi:10.1016/j.envint.2019.105315

Cited by 73 publications

(65 citation statements)

References 36 publications

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“…Among such instances, a Chinese study found that exposure to moderately high fluoride in childhood could cause the loss of excellent intelligence [ 15 ]. A cohort study in Canada also reported that water fluoride concentration was associated with intelligence loss of formula-fed children, and the mean fluoride concentrations in the drinking water in the fluoridated and non-fluoridated communities appeared same as the study of Green et al (2019) [ 16 ]. Meanwhile, no association between excessive fluoride and IQ scores were observed in a community water fluoridation program in New Zealand, where the fluoride concentration ranged from 0.7 to 1.0 mg/L [ 17 ].…”

Section: Introductionsupporting

confidence: 51%

RETRACTED ARTICLE: Fluoride exposure and intelligence in school-age children: evidence from different windows of exposure susceptibility

Huang

et al. 2020

BMC Public Health

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Background The intellectual loss induced by fluoride exposure has been extensively studied, but the association between fluoride exposure in different susceptibility windows and children’s intelligence is rarely reported. Hence, we conducted a cross-sectional study to explore the association between fluoride exposure in prenatal and childhood periods and intelligence quotient (IQ). Methods We recruited 633 local children aged 7–13 years old randomly from four primary schools in Kaifeng, China in 2017. The children were divided into four groups, of which included: control group (CG, n = 228), only prenatal excessive fluoride exposure group (PFG, n = 107), only childhood excessive fluoride exposure group (CFG, n = 157), both prenatal and childhood excessive fluoride exposure group (BFG, n = 141). The concentrations of urinary fluoride (UF) and urinary creatinine (UCr) were determined by fluoride ion-selective electrode assay and a creatinine assay kit (picric acid method), respectively. The concentration of UCr-adjusted urinary fluoride (CUF) was calculated. IQ score was assessed using the second revision of the Combined Raven’s Test-The Rural in China (CRT-RC2). Threshold and saturation effects analysis, multiple linear regression analysis and logistic regression analysis were conducted to analyze the association between fluoride exposure and IQ. Results The mean IQ score in PFG was respectively lower than those in CG, CFG and BFG (P < 0.05). The odds of developing excellent intelligence among children in PFG decreased by 51.1% compared with children in CG (OR = 0.489, 95% CI: 0.279, 0.858). For all the children, CUF concentration of ≥1.7 mg/L was negatively associated with IQ scores (β = − 4.965, 95% CI: − 9.198, − 0.732, P = 0.022). In children without prenatal fluoride exposure, every 1.0 mg/L increment in the CUF concentration of ≥2.1 mg/L was related to a reduction of 11.4 points in children’s IQ scores (95% CI: − 19.2, − 3.5, P = 0.005). Conclusions Prenatal and childhood excessive fluoride exposures may impair the intelligence development of school children. Furthermore, children with prenatal fluoride exposure had lower IQ scores than children who were not prenatally exposed; therefore the reduction of IQ scores at higher levels of fluoride exposure in childhood does not become that evident.

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Section: Introductionsupporting

confidence: 51%

RETRACTED ARTICLE: Fluoride exposure and intelligence in school-age children: evidence from different windows of exposure susceptibility

Huang

et al. 2020

BMC Public Health

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“…In an extension of the MIREC study of prenatal fluoride exposures, the authors subsequently assessed the possible impact of fluoride exposure from reconstituted formula in fluoridated and non-fluoridated communities [123]. After adjustment for prenatal fluoride exposure and other covariates, each increase by 1 mg/L in the water fluoride concentration was found to be associated with a statistically significant decrease of 8.8 IQ points in the children who had been formula-fed in the first 6 months of life, while no such difference was seen among the exclusively breastfed children.…”

Section: Resultsmentioning

confidence: 99%

“…Subsequent epidemiological studies have strengthened the links to deficits in cognitive functions, several of them providing individual exposure levels, though most of the new studies were cross-sectional and focused on populations with fluoride exposures higher than those typically provided by fluoridated water supplies. Prospective studies from the most recent years document that adverse effects on brain development happen at elevated exposure levels that occur widely in North America and elsewhere in the world, in particular in communities supplied with fluoridated drinking water [24, 63, 116, 123]. These new prospective studies are of very high quality and, given the wealth of supporting human studies and biological plausibility, leave little doubt that developmental neurotoxicity is a serious risk associated with elevated fluoride exposure, especially when this occurs during early brain development.…”

Section: Plausibility and Implicationsmentioning

confidence: 99%

“…These new prospective studies are of very high quality and, given the wealth of supporting human studies and biological plausibility, leave little doubt that developmental neurotoxicity is a serious risk associated with elevated fluoride exposure, especially when this occurs during early brain development. While evidence on the neurotoxic impact of early postnatal exposure remains limited [21, 123], other neurotoxicity evidence suggests that adverse effects are highly plausible [124].…”

Section: Plausibility and Implicationsmentioning

confidence: 99%

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Developmental fluoride neurotoxicity: an updated review

Grandjean

2019

Environ Health

150

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Background: After the discovery of fluoride as a caries-preventing agent in the mid-twentieth century, fluoridation of community water has become a widespread intervention, sometimes hailed as a mainstay of modern public health. However, this practice results in elevated fluoride intake and has become controversial for two reasons. First, topical fluoride application in the oral cavity appears to be a more direct and appropriate means of preventing caries. Second, systemic fluoride uptake is suspected of causing adverse effects, in particular neurotoxicity during early development. The latter is supported by experimental neurotoxicity findings and toxicokinetic evidence of fluoride passing into the brain. Method: An integrated literature review was conducted on fluoride exposure and intellectual disability, with a main focus on studies on children published subsequent to a meta-analysis from 2012. Results: Fourteen recent cross-sectional studies from endemic areas with naturally high fluoride concentrations in groundwater supported the previous findings of cognitive deficits in children with elevated fluoride exposures. Three recent prospective studies from Mexico and Canada with individual exposure data showed that early-life exposures were negatively associated with children's performance on cognitive tests. Neurotoxicity appeared to be dose-dependent, and tentative benchmark dose calculations suggest that safe exposures are likely to be below currently accepted or recommended fluoride concentrations in drinking water. Conclusion: The recent epidemiological results support the notion that elevated fluoride intake during early development can result in IQ deficits that may be considerable. Recognition of neurotoxic risks is necessary when determining the safety of fluoride-contaminated drinking water and fluoride uses for preventive dentistry purposes.

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“…A recent 2020 study by Till et al of Canadian cohort children compared IQ scores in 398 children who were formula-fed versus breastfed during infancy [156]. This detailed analysis indicates that fluoride intake among infants younger than six months may exceed the tolerable upper limits if they are fed exclusively with formula reconstituted with fluoridated tap water.…”

Section: Developmental Neurotoxicity Of Fluoride In Childrenmentioning

confidence: 99%

Mechanisms of Fluoride Toxicity: From Enzymes to Underlying Integrative Networks

Strunecká

Strunecký

2020

Applied Sciences

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Fluoride has been employed in laboratory investigations since the early 20th century. These studies opened the understanding of fluoride interventions to fundamental biological processes. Millions of people living in endemic fluorosis areas suffer from various pathological disturbances. The practice of community water fluoridation used prophylactically against dental caries increased concern of adverse fluoride effects. We assessed the publications on fluoride toxicity until June 2020. We present evidence that fluoride is an enzymatic poison, inducing oxidative stress, hormonal disruptions, and neurotoxicity. Fluoride in synergy with aluminum acts as a false signal in G protein cascades of hormonal and neuronal regulations in much lower concentrations than fluoride acting alone. Our review shows the impact of fluoride on human health. We suggest focusing the research on fluoride toxicity to the underlying integrative networks. Ignorance of the pluripotent toxic effects of fluoride might contribute to unexpected epidemics in the future.

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Fluoride exposure from infant formula and child IQ in a Canadian birth cohort

Cited by 73 publications

References 36 publications

RETRACTED ARTICLE: Fluoride exposure and intelligence in school-age children: evidence from different windows of exposure susceptibility

RETRACTED ARTICLE: Fluoride exposure and intelligence in school-age children: evidence from different windows of exposure susceptibility

Developmental fluoride neurotoxicity: an updated review

Mechanisms of Fluoride Toxicity: From Enzymes to Underlying Integrative Networks

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