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Fluoridation of public water supplies could effectively become compulsory in Aotearoa New Zealand. A bill before parliament proposes that district health boards (rather than councils) be made responsible for water fluoridation. We all want good dental health, but a number of recent studies show reduced cognitive ability in children who were exposed to fluoride in the womb. Dr John Christie asks: how safe is fluoridation?

In Augusl 2019 the journal JAMA Pediatrics published the result of a study of Canadian women and their young children which found a significant negative association between the mothers’ fluoride exposure during pregnancy and the lQ of their children at age four (Green 2019).

Translated to New Zealand (Cressey 2010) the results imply an average IQ loss of about 4 points in non-fluoridated towns and cities, where tea is the main source of fluoride (e.g. Christchurch), and 9 in those with fluoridated drinking water, such as Auckland and Wellington …

NOT AN ISOLATED STUDY

In the last four years several high-quality studies showing an association between prenatal exposures to fluoride and diminished cognitive abilities have been published (Bashash 2017, Valdez Jimenez 2017, Green 2019, Till 2020a).

All studies that have measured foetal exposure to fluoride have found such an effect (Grandjean 2020). A 2012 review of 27 earlier, mostly Chinese, studies found the average IQ in high fluoride areas was 6.75 points lower than in low fluoride areas (Choi 2012, Choi 2013).

Other recent studies have found increased fluoride exposure was associated with increased incidence of ADHD (Bashash 2018, Riddell 2019). Summarising the evidence, Harvard university’s Professor Philippe Grandjean concluded in a recent review ‘there is little doubt that developmental neurotoxicity is a serious risk associated with elevated fluoride exposure, whether due to community water fluoridation, natural fluoride release from soil minerals, or tea consumption, especially when the exposure occurs during early development.’ (Grandjean 2019).

PERMANENT DAMAGE TO THE BRAIN

In an earlier paper Grandjean explained in The Lancet that neurotoxic damage is likely to be permanent: ‘The developing human brain is inherently much more susceptible to injury caused by toxic agents than is the brain of an adult … Because of the extraordinary complexity of human brain development, windows of unique susceptibility to toxic interference arise that have no counterpart in the mature brain or in any other organ. If a developmental process in the brain is halted or inhibited, there is little potential for later repair, and the consequences can therefore be permanent.’ (Grandjean 2006)

The JAMA Pediatrics paper (Green 2019) reports that lower IQs are associated with, rather than caused by fluoride exposure. This is because it is difficult in epidemiology (population health studies) to prove causation. Commonly the likelihood of causation is assessed using the Bradford Hill criteria, named after the British statistician who described them to the Royal Society of Medicine in 1964.

HEED THE SCIENCE

Andrew Little recently said: “Let’s challenge those who want to ignore the science” (Sivignon 2021). I completely agree. The science says water fluoridation has an uncertain and probably small benefit, and that the risk of permanent brain damage in very young children is high. This is science that should not be ignored. It would be very useful to talk to your local MP – show him or her a copy of this article, with its references. The listed scientific journals are of the highest quality – they do not publish ‘junk science’.

Grandjean, an expert neurotoxicologist, recently judged fluoride exposure to meet 8 of the 9 criteria (Grandjean 2020). The ninth criterion, specificity, supports causation if it exists but does not rule it out if not, as Bradford Hill himself pointed out (Hill 1965). Specificity would exist here if IQ losses were associated with fluoride exposure and nothing else.

SO WHAT SHOULD WE DO?

The available evidence suggests that the current fluoride exposure levels in New Zealand are causing brain damage in children. This affects about one third of the current population. The Canadian paper was published over 17 months ago now. In this time there have been more than 80,000 births in New Zealand – many more babies at risk – and there is still no response from the Ministry of Health (MOH).

So we all have to take matters into our own hands. The advice from both the authors of the Canadian study (Green 2019) and the editor of JAMA Pediatrics (Christakis 2019) is for pregnant women to minimise fluoride intake. Since rapid brain development continues up to age five, parents should minimise intake by young children.

Most important is to cease drinking fluoridated water and tea. It is especially important not to use fluoridated water in infant formula (Till 2020a) or to use infant foods containing fluoridated water. Fluoride intake can be further reduced by not eating foods such as bread made using fluoridated water (Cressey 2010). If possible, buy products from non-fluoridated areas such as Christchurch. Intake from fluoride toothpastes is negligible for adults but it would be prudent to for children to use non-fluoridated toothpaste.

Fluoride avoidance is necessary because the evidence of neurotoxic danger is strong and the consequences very serious. In contrast the evidence for dental benefit from water fluoridation is weak (NHS 2000, Schluter 2020), and whereas dental decay can be treated (preferably in fact prevented, through a healthy diet and good dental hygiene), brain damage cannot.

Key precautions for pregnant women and young children (Till 2019)

• Avoid fluoridated water
• Minimise consumption of tea

Precautions should continue as long as possible. The brain develops rapidly up to age two, expands another 10% by age five and is now known to continue developing past age 20 (Lenroot 2006).

All types of tea (black, green, white and oolong) contain relatively high concentrations of fluoride, but actual amounts vary according to the source, the highest from Kenya, lowest from Sri Lanka. Fluoride intake also varies with the method of preparation; the common Chinese practice of discarding the first infusion reduces fluoride intake by 80% (Waugh 2017).

References

Bashash, M et al. 2017. Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6-12 years of age in Mexico. Environmental Health Perspectives 125, 097017.

Bashash, Met al. 2018. Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6-12 years of age in Mexico
City. Environ, Int. 121, 658-666.

Choi, A et al. 2012, Developmental fluoride neurotoxicity: A systematic review and meta-analysis. Environmental Health Perspectives 120, 1362.

Choi, A et al 2013, Developmental fluoride neurotoxicity: Choi et al. respond. Environmental Health Perspectives 121, a70.

Christakis, M. 2019. Quoted in ‘Is Fluoride in Drinking Water Safe? A New Study Reignites a Long-Standing Debate’, Time 20 Aug 2019.

Cressey, Pet al. 2010. Estimated dietary fluoride intake for New Zealanders. Journal of Public Health Dentistry 70, 327.

Grandjean, P et al. 2006 Developmental neurotoxicity of industrial chemicals. The Lancet 368, 2167.

Grandjean, P. 2019. Developmental fluoride neurotoxicity: An updated review. Environmental Health 18, 110.

Grandjean, P. 2020. Food and Water Watch, et al. v U.S. EPA, Expert Declaration of Philippe Grandjean, MD, MSc_ Report No.198-3, US Federal Court.

Green, R et al. 2019. Association between maternal fluoride exposure during pregnancy and 10 scores in offspring in Canada. JAMA Pediatrics 173, 940.

Hill, AB.1965. The environment and disease: Association or causation? Proc. R. Soc. Med. 58, 295.

Lenroot, RK et al. 2006. Brain development in children and adolescents: Insights from anatomical magnetic resonance imaging. Neuroscience & Biobehavioral Reviews 30, 718.

NHS Centre for Reviews and Dissemination 2000. A systematic review of public water fluoridation. University of York.

Riddell, JK et al, 2019. Association of water fluoride and urinary fluoride concentrations with attention deficit hyperactivity disorder in Canadian youth. Environment International 133, 105190.

Rugg-Gunn, A. 2001. Preventing the preventable: The enigma of dental caries. British Dental Journal 191, 478.

Schluter, PJ et al. 2020. Association between community water fluoridation and severe dental caries experience in 4-year-old NZ children. JAMA Pediatr.
174,969.

Sivignon, C. 2021. Government considers water fluoridation policy, says Andrew Little. Stuff 22 Jan 2021.

Till, C 2019. Ways for pregnant women to reduce fluoride exposure. This is a flyer by one of the senior authors of [Green 2019].

[Till 2020a] Till, C et al. 2020. Fluoride exposure from infant formula and child 10 in a Canadian birth cohort. Environment International 134, 105315.

[Till 2020b] Till, C et al. 2020. The evolving science of fluoride: When new evidence doesn’t conform to existing beliefs. Pediatr Res. 22.05.2020.

Valdez Jimenez, Let al. 2017. In utero exposure to fluoride and cognitive development delay in infants. Neurotoxicology 59, 65-70.

Waugh, DT et al 2017. Black tea source, production, and consumption: Assessment of health risks of fluoride intake in New Zealand. Journal of Environmental and Public Health 2017, 5120504.

*Read the full article online at http://fluoridealert.org/wp-content/uploads/christie-2021.pdf

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