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From the Townsend Letter
April 2016

Prenatal Fluoride and Autism
by John D. MacArthur
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US Fetuses Overdosed with a'Developmental Neurotoxicant'
In 2009, researchers at the EPA's Neurotoxicology Division found "substantial evidence" that fluoride is "toxic to the developing mammalian nervous system."58 Pregnant women already minimize or avoid other "developmental neurotoxicants" in the same category with fluoride: ethanol (alcohol), nicotine, diazepam (Valium), caffeine, lead, arsenic, amphetamine. They're also advised to avoid tetracycline, even though the EPA has only "minimal evidence" of its developmental neurotoxicity.
Fluoridation promoters say not to worry because "dose makes the poison, and the recommended level of fluoride in US drinking water is only 0.7 mg/l" (a concentration, not a dose). When it comes to neurodevelopment, however, a toxic substance's capacity to disrupt the developing brain does not simply depend upon dose. It also depends upon the "duration of exposure, and most important, on the timing during the developmental process," says the National Scientific Council on the Developing Child.59
In 1997, the Institute of Medicine (IOM) established 0.7 mg of fluoride per day as a Tolerable Upper Intake Level (UL) for infants 0 to 6 months old (based on US research from the 1930s and 1940s).60 A UL is the maximum level of total chronic daily intake that is unlikely to pose risks of adverse effects to the most sensitive members of the healthy population.61 A fetal UL was not determined but would be significantly lower, because in the unborn fetus, "sensitivity increases due to active placental transfer, accumulation of certain nutrients in the amniotic fluid, rapid development of the brain."62
Fetal blood levels of fluoride can vary widely, but they average about two-thirds of maternal levels. Therefore, when a pregnant woman consumes 3 mg of fluoride, her fetus is exposed to the equivalent of consuming about 2 mg of fluoride – an amount nearly three times the Tolerable Upper Intake Level of a 6-month-old infant.
"As intake increases above the UL," the IOM says "the risk of adverse effects increases."63 Again, fluoridation promoters say not to worry, because the only adverse developmental effect from a chronic intake of fluoride above its UL is dental fluorosis, a cosmetic not a health issue. "Because the cosmetic effects of the milder forms of enamel fluorosis are not readily apparent," the IOM selected moderate enamel fluorosis as the critical adverse effect for infants and children.64
The IOM did not consider adverse neurological effects, only dental fluorosis. There is, however, a connection between tooth development and brain development.

Developmental Defects Increase with Fluoride Levels in Drinking Water
All enamel defects are indications of severe stress, because they result from systemic cellular disruption during prenatal and early postnatal life that can affect other ectodermally derived structures, including the brain. Chronologically distributed enamel defects are a valuable aid in neurologic diagnosis, since they occur commonly in brain-damaged children. Developmental enamel defects in primary teeth have been found at least twice as frequently in children with mental retardation as in control children.65,66
Some enamel defects are essentially birth defects resulting from a pregnant woman's consumption of fluoride. Similarly, a thin upper lip and flattened philtrum (the groove in the middle of the upper lip) are birth defects resulting from consumption of alcohol during pregnancy. They certainly signify more than a cosmetic effect, as does the gray-blue line on the gums of people with lead poisoning.
Dental studies show that the prevalence and severity of developmental defects of enamel in children increase significantly as fluoride levels in drinking water increase from less than 0.2 mg/l to more than 0.7 mg/l.67-70 Fluoride supplements (0.25 to 0.75 mg/day) are also associated with developmental defects of enamel.71 Note: research shows that the use of fluoride supplements (1.5 mg/day) during pregnancy doubles fetal blood concentrations of fluoride.72
Fluoride levels in amniotic fluid have been positively correlated in a dose-response relationship with fluoride content and pathology of fetal bones – with significantly greater fluoride levels in fetuses born to mothers with dental fluorosis.73
British researchers estimate the prevalence of dental fluorosis of all levels of severity to be 15% in nonfluoridated areas and 48% in fluoridated areas.74
Choi et al. (2015) found that developmental neurotoxicity was associated with dental fluorosis. Children with fluoride-induced mottling of their teeth – even the mildest form that appears as whitish specks on the enamel – showed lower performance on some neuropsychological tests.75,76

Genetic Susceptibility to Fluoride's Adverse Effects
Fluorosis severity does not depend just on the amount of fluoride that one consumes. There are individual genetic and metabolic factors involved (as there are in autism spectrum disorders). Animal studies reveal a genetic component in the pathogenesis of dental fluorosis and in bone response to fluoride exposure.77 In humans, severity of dental fluorosis varies individually at the same level of intake.72
Genetic sensitivity to fluoride's adverse neurological effects was confirmed by Zhang et al. (2015), who found that children with a variation of the COMT gene, which is associated with cognitive performance, had steeper cognitive decline from exposure to fluoride. Also, poor IQ scores were observed in the high fluoride exposure group (1.4 mg/l) compared with controls (0.63 mg/l).78 Note: for generations, the recommended fluoride level in US public drinking water was allowed to range up to 1.7 mg/l.

SSRIs and Autism
In genetically susceptible individuals, autism may result from maternal exposure of a fetus to minute concentrations of pharmaceuticals, such as Prozac, a selective serotonin reuptake inhibitor (SSRI).79 Because serotonin is critical to fetal brain development, concerns have arisen regarding prenatal exposure to SSRIs that manipulate serotonin levels 80 Serotonin elevation in the blood is one of the better-documented and consistent findings in autism and is probably gastrointestinal in origin 81 Note: 95% of the serotonin in the body is located in the gut.
Research shows that prenatal exposure to SSRIs is associated with an increased risk of autism.82 A major study published in December 2015 looked at outcomes of 145,456 pregnancies over 12 years. The University of Montreal researchers found that taking SSRIs during the second or third trimester of pregnancy more than doubled a child's risk of being diagnosed with autism by age seven.83
Two of the most commonly prescribed SSRIs, Prozac (fluoxetine) and Paxil, contain fluorinated compounds. According to Gary M. Whitford, PhD, DMD, an expert on fluoride metabolism, a 20 mg dose of fluoxetine can provide up to 3.3 mg of fluoride, "depending on how much fluoride ion is released during the drug's metabolism."84 Note: Whitford was a key member of the Institute of Medicine panel that determined dietary reference intakes for fluoride.

Preeclampsia, Autism, and Fluoride
Taking SSRIs during pregnancy is also associated with preeclampsia, the dangerous pregnancy complication with immediate and lifelong consequences for mother and child. In a study involving 5731 pregnant women, the incidence of preeclampsia was 15.2% among those who continued SSRIs beyond the first trimester, compared with 2.4% among nonusers.85
Preeclampsia also increases the risk of having a child with autism spectrum disorder, and risk increases with greater preeclampsia severity.86,87 Preeclampsia has the same key subcellular mechanism of pathogenesis as dental and skeletal fluorosis, endoplasmic reticulum (ER) stress. In fluorosis, fluoride causes the ER stress. In preeclampsia, the cause is still unknown (as discussed by the author).88
Fujita et al. (2010) found that autism spectrum disorder is related to ER stress induced by mutations in the genes encoding synaptic cell adhesion molecules, and that PSD-95 is involved.89,90 As discussed above, fluoride decreases the expression level of PSD-95 in the brain.

Fluoride, Premature Birth, and Autism
Substantial laboratory and clinical evidence suggests that maternal fluoride consumption is a risk factor for premature birth, a leading cause of long-term neurological disabilities in children (as discussed by the author).91 Premature birth is also significantly associated with autism. Large-scale population-based studies show that the prevalence of autism is 2 to 4 times higher in preterm children than in children born at full term.92,93
The preterm gut experiences abnormal bacterial colonization with a decreased rate of diversification and altered microbiome composition. It also has an increased number of pathogenic bacteria.12 Placentas collected after preterm births have significantly lower levels of bacteria that act a bit like natural versions of medications used to stop preterm contractions.94
A December 2015 review concluded, "The maternal oral, vaginal, and gut microbiome influence the risk of pregnancy outcomes that have profound impacts upon the health of the neonate and infant, including preterm birth, preeclampsia, gestational diabetes, and excessive gestational weight gain."95

Hypothyroidism, Autism, ADHD, and Fluoridated Water
Fluoride effects on thyroid function are well documented. Thyroid hormones are essential for fetal and neonatal brain development, and even slight alterations during critical periods of development can have severe consequences on the development of the child.96 Andersen et al. (2015) observed that children born to mothers with thyroid dysfunction had an increased risk of developing autism spectrum disorders, attention deficit/hyperactivity disorders (ADHD), and psychiatric disease in adolescence and young adulthood.97 Klein et al. (2001) found an inverse correlation between severity of women's hypothyroidism and the IQ of their children.98
In 2015, a major population-level study that analyzed data from 99% of England's 8020 general medical practices showed a positive association between patients diagnosed with hypo-thyroidism and fluoride levels in their drinking water. High hypothyroidism prevalence was 30% more likely in practices located in areas with fluoride levels in drinking water in excess of 0.3 mg/l. Practices located in the West Midlands (a wholly fluoridated area) were nearly twice as likely to report high hypothyroidism prevalence in comparison to Greater Manchester (nonfluoridated area).99
The study did not include undiagnosed subclinical hypo-thyroidism. The National Research Council (2006) said that in pregnant women, subclinical hypothyroidism is associated with "decreased IQ of their offspring."100
The most common neuro-developmental disorder of childhood is ADHD. Another large-scale population-based study published in 2015 revealed that artificial water fluoridation prevalence was significantly positively associated with ADHD prevalence in the US. After controlling for socioeconomic status, each 1% increase in artificial fluoridation prevalence in 1992 was associated with approximately 67,000 to 131,000 additional ADHD diagnoses from 2003 to 2011.101

More Fluoride Absorbed from Artificially Fluoridated Water
Fluoridation promoters claim that because fluoride compounds have always been naturally present in drinking water, fluoride cannot be a factor in the increasing prevalence of developmental neurotoxicity. However, they overlook the fact that the degree of absorption of any fluoride compound after ingestion is correlated with its solubility. The readily water-soluble industrial fluorides (sodium fluoride, sodium silicofluoride, fluorosilicic acid) used to artificially fluoridate drinking water are rapidly and almost completely absorbed, in contrast to low-soluble natural compounds such as calcium fluoride. The solubility of fluoride correlates generally with the degree of toxicity.72,102
Industrial fluorides are added to nearly three-fourths of US public water supplies; therefore substantial amounts of fluoride are also ingested from foods and beverages processed in fluoridated cities. Note: women are advised to drink more water when pregnant.

Fluoride, Copper, and Autism
Water fluoridation chemicals have been shown to increase the leaching of lead and copper from brass plumbing fixtures into tap water (as discussed by the author).103 Copper has an antagonistic relationship with zinc. Excess copper levels and zinc deficiency are common in children diagnosed with an autism spectrum disorder.104
Due to the multifaceted effect of zinc on gut development, it is likely that insufficient zinc supply will affect development of the fetal GI tract, contributing to many of the reported GI problems associated with autism.105

Prenatal Fluoride: All Risk and No Benefit
The US Food and Drug Administration (FDA) has classified fluoride as a Pregnancy Category C drug, which "may pose risks similar to a drug in Category X."106 The risks of a Category X drug clearly outweigh potential benefits.
What are the potential benefits of ingesting fluoride during pregnancy? For the child, none. The FDA has long prohibited claims that prenatal fluoride supplements benefit the teeth of children.107 For the mother: "No published studies confirm the effectiveness of fluoride supplements in controlling dental caries among persons ages >16 years."108 A 2015 Cochrane Review could not identify any evidence determining the effectiveness of water fluoridation for preventing caries in adults.109

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