In a study published in August in the Journal of the American Medical Association, Canada-based researchers showed a significant drop in children’s intelligence quotient (IQ) scores as a result of gestational exposure to fluoride.

The researchers found that for every 0.33 mg/L increase of fluoride in the water that women consumed, 1.5 IQ points were lost in their offspring. Additionally, for every 0.7 mg/L increase, 3 IQ points were lost in young males specifically.(1)

In Ireland, the optimal levels of fluoride in drinking water for prevention of dental caries are 0.6-0.8 ppm (mg/L) – so for every litre of water you drink, there is an average value of 0.7 mg fluoride present.(2)

The study also highlighted that little research has been conducted on how fluoride exposure affects the different sexes, especially in light of the fact that “boys have a higher prevalence of neurodevelopmental disorders such as ADHD, learning disabilities, and intellectual disabilities”.(1)

Subjectivity of test

Do three IQ points really make a difference, some might ask? Perhaps not, and many would argue that IQ tests are relatively subjective.

Nonetheless, the children were assessed using the Wechsler Preschool and Primary Scale of Intelligence test to evaluate skills such as verbal/non-verbal reasoning, verbal comprehension, spatial processing, visual motor skills and general intellectual functioning, all of which would be considered critical indicators of the disorders listed above.

Pregnant tea drinkers

However, water is not the sole source of dietary fluoride. The researchers took into consideration how many cups of tea the women drank throughout their pregnancy, as green and black tea contain 1.9 mg/L and 2.6 mg/L fluoride, respectively.(3,4)

The Food Safety Authority of Ireland (FSAI) released their report on dietary fluoride exposure across the isle in 2018. They estimated that 76 per cent of total fluoride exposure in Irish adults could be attributed to the consumption of black tea.(5)

The FSAI report also compared their estimated daily fluoride exposure limits to the upper limits for safe exposure set by the European Food Safety Authority (EFSA, 2005). While the FSAI report highlights that all population groups were below these limits, in light of this new data on IQ effects, our exposure levels are still quite concerning.

Postnatal exposure

For example, the FSAI report estimates that adults (18+ years) and pre-school children (1-4 years) are exposed to 0.040 and 0.023 mg/kg of bodyweight daily. Assuming that an adult weighs 70kg (as recommended in the report) and that a four-year-old child weighs about 17 kg (averaged paediatric norms),6 then the total ingested daily fluoride shoots up to 2.8 mg and 0.3 mg for adults and children, respectively.

This could potentially equate to an IQ loss of 12 points for every Irish adult, and counting. Of course this is assuming that postnatal exposure to fluoride affects IQ scores in the same way as maternal exposure.

Dental caries

It must be said that there is a wealth of evidence to show that water fluoridation has produced a significant decrease in dental caries rates in many populations across the world.

But this does not address the root cause of dental caries, which arises from excessive sugar in the diet.7 Better dietary choices are simple interventions that can be implemented from birth in order to prevent tooth decay.

Still, a child’s IQ is a very different, and much less straightforward matter. One must weigh the risks of potential IQ loss in children against the benefits of preventable dental decay. It has been a controversial subject in Irish news for the past decade, but are we discussing the issue enough?

Fluoride debate

Until the Irish Government re-evaluates its stance on the age-old fluoride debate in light of this new evidence, every effort must be made towards ensuring this information reaches expectant mothers, allowing them to make informed decisions regarding their health and their children’s health.

References:

1. Green R, Lanphear B, Hornung R, et al. Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada. JAMA Pediatr. 2019;173(10):940-948. doi:10.1001/jamapediatrics.2019.1729.
2. https://www.hse.ie/eng/services/list/1/environ/fluoridation-faqs-1-.pdf.
3. Waugh DT, Potter W, Limeback H, Godfrey M. Risk Assessment of fluoride intake from tea in the Republic of Ireland and its implications for public health and water fluoridation. Int J Environ Res Public Health. 2016;13(3):259. doi:10.3390/ ijerph13030259.
4. USDA Nutrient Data Laboratory Beltsville Human Nutrition Research Center Agricultural Research Service. USDA National Fluoride Database of Selected Beverages and Foods. https://www.ars.usda.gov/SP2UserFiles/Place/ 80400525/Data/Fluoride/F02.pdf. Published 2005.
5. https://www.fsai.ie/publications/fluoride_study_2014-2016/.
6. http://www.dmconsortium.org/filesimages/clerkship%20resources/peds_pediatric_norms.pdf.
7. https://www.dentalhealth.ie/dentalhealth/causes/dentalcaries.html.

*Original article online at https://www.imt.ie/opinion/lets-talk-fluoride-irish-public-drinking-water-supplies-25-11-2019/