Health and Safety of Community Water Fluoridation

              One of the largest debates in the realm of human health is the controversy surrounding community water fluoridation and its systemic effects. There are numerous arguments opposing the addition of fluoride to drinking water, based on its seemingly negative impact on various aspects of physiological health. The idea that fluoride exposure has a correlation to a decrease in IQ has been researched and debated extensively. Similarly, the effect of fluoride intake on parts of the body, such as the thyroid and pineal glands, is a common component in the dispute on water fluoridation. Widespread and concerning, fluorosis is a massive factor in the discussion on fluoride health and safety. Dental fluorosis is a frequent topic that oral health professionals are privy to, as well as the positive impact that community water fluoridation has on the incidence of dental caries. Overall, the discourse on fluoride is of utmost importance, and it is essential that the health benefits and disadvantages of community water fluoridation are studied and understood.

  One common component of the dispute around community water fluoridation is the contingency of it’s possible adverse effect on the cognitive development of children. Fluoride’s influence on the young population has been studied at length in an attempt to determine if a correlation exists between the intelligence quotient’s of children and their exposure to fluoride, both directly and via maternal consumption during pregnancy. “A study published by a group of researchers in Canada and the US after the CADTH HTA concluded that exposure to higher levels of fluoride during pregnancy is associated with lower IQ scores in children aged 3 to 4 years in Canada.”¹ The study took into account maternal urinary fluoride (MUFSG) as well as the daily fluoride intake of the mothers.¹ “A 1-mg/L increase in MUFSG was associated with a 4.49-point lower IQ score (95% CI, −8.38 to −0.60) in boys, but there was no statistically significant association with IQ scores in girls (B = 2.40; 95% CI, −2.53 to 7.33). A 1-mg higher daily intake of fluoride among pregnant women was associated with a 3.66 lower IQ score (95% CI, −7.16 to −0.14) in boys and girls.”² The conclusion drawn from the MUFSG was odd and arguably insignificant due to the variation of effects based on sex, however the correlation between the daily fluoride intake of  mothers and the decreased IQs of their toddlers is consistent regardless of sex. Knowing all the facts, it can be concluded that daily maternal fluoride intake does correlate to a slight decrease in child IQ, however maternal urinary fluoride does not seem to have a consistent correspondence to IQ levels.

  Another study examined the the cognitive effects of direct fluoride intake on children 6-14 years of age.² “The studies (88%, n = 50) which found relation between fluoride and neuronal impacts were carried out in China, India, Iran, and Mexico”² however, the fluoride concentrations present in the studies shown are much different than those in average Canadian drinking water. Certain area’s studied had water fluoride concentrations as high as 8.4ppm which is twelve times the optimal fluoride concentration.² This indicates that the “generalizability of the findings from those studies to the Canadian context is unlikely given they were conducted in rural areas and areas of low socioeconomic status in countries, such as China, India, Iran, or Mexico, which also include other sources of fluoride such as fluoridated salts or naturally occurring water fluoride levels that are many folds higher than the current Canadian levels.”³ Along with the extremely high concentration of water fluoride, “multiple methodological limitations were identified in these studies including the lack of control for important confounding variables such as exposure to known neurotoxicants (e.g., lead, arsenic, or iodine), socioeconomic status, nutritional status, and parental education that could be related to fluoride exposure and also potentially affect children’s IQ.”³ From these studies it is indicated that direct intake of fluoride does relate to a decline in adolescent’s cognitive ability. This, however, was determined in areas with fluoride concentrations much higher than the agreed upon maximum acceptable concentration (MAC) in Canada, indicating that the findings would likely not be reflected in first world countries.

  The calcification and dysfunction of various glands in the body, including the thyroid and pineal glands, has been a prevalent concern in relation to community water fluoridation. Thyroid impairment is a ubiquitous issue globally and has been thought to correlate with fluoride intake, prompting various studies on the matter. One particular study observed levels of numerous hormones, pertaining to the thyroid, in three groups of children each with a subsequently increasing level of fluoride exposure.⁴ “It showed a nonsignificant association between thyroid function and long-term systemic intake of fluoride up to 1.4 ppm.”⁴ Unlike some, this study is useful because of its pertinence to first world countries, concluding that there is no correlation “between dental fluorosis and thyroid function in children residing in near-optimal naturally fluoridated areas (0.2–1.4 ppm) with normal nutritional status and optimal iodine intake.”⁴ Similar to the thyroid gland, the pineal gland, in the human brain, is thought to be impacted by systemic fluoride. While unequivocal evidence that fluoride inhibits pineal function has not been found, there are studies showing that systemic fluoride does accumulate in the pineal gland.⁵ This finding, however, is not necessarily indicative of fluoride being detrimental because the calcification of the pineal gland is inevitable, regardless of fluoride exposure. Calcium naturally accumulates in the gland, and the rate of pineal calcification has not been shown to increase with any level of fluoride exposure. Knowing this, it is evident that community water fluoridation has not been found as a cause of thyroid or pineal gland dysfunction.

  Arguably, one of the most popular side effects of ingested fluoride is fluorosis. “When excessive amounts of systemic fluoride are responsible for enamel hypoplasia or enamel hypocalcification, this condition is classified as dental fluorosis.”⁶ Similarly, when this anomaly takes place in the bones, it is termed skeletal fluorosis and is “a serious concern to be taken into consideration and to be dealt with effectively.”⁷ Dental fluorosis is only a risk during tooth development and cannot affect the teeth post-eruption. Skeletal fluorosis, however, is a risk associated with excessive fluoride intake throughout life, and increases the incidence of bone fractures and deformities while also causing pain and stiffness.⁸ One study looks at the prevalence of skeletal fluorosis in places such as Iran, and shows that it is inevitably an unfortunate challenge faced by that population due to the extremely high levels of fluoride that they are exposed to.² The issue with this study is that it has limited relevance to Canadians because the fluoride levels in Canada are about one fifteenth of those researched in Iran.² Dental fluorosis, on the other hand, is a disadvantage of water fluoridation, but most cases are only aesthetic issues, as dental fluorosis is not a health concern unless it is severe. Thus, the issue of dental fluorosis has less gravity in the discussion on health and safety of community water fluoridation, simply because the aesthetic consequences are outweighed by the health benefits. Also, the risk of skeletal fluorosis is not a strong opposition of water fluoridation because the optimal concentration of fluoride is not enough to cause skeletal fluorosis.

  The big benefit of community water fluoridation is its significant impact of caries reduction. Studies done in the early 1900‘s, reported by the World Health Organization, show that “at 1 mg of fluoride per litre [of water], the reduction in the prevalence of dental caries was approximately 50% compared with communities with less than 0.1 mg of fluoride in their drinking water.”⁹ The reduction of dental caries is definitely a significant success in the improvement of overall human health and has been attributed as one of the ten great public health achievements of the 20th century by the Centers for Disease Control and Prevention.¹⁰ The positive impact of community water fluoridation on oral health is further emphasized by studies conducted in the early 2000s on the effects of cessation on dental caries in children. ¹¹  “Findings were consistent with an adverse effect of fluoridation cessation on children’s caries experience, about 2.5–3 years post-cessation.”¹¹ These studies indicate a clear benefit of community water fluoridation on dental caries. It is important to give adequate credit to the advancement of oral health, that has been achieved by water fluoridation, as the oral cavity and its wellbeing are massive indicators and mediators of the health and wellness of the rest of the body.

  In conclusion, the benefits of fluoride are clear, however, they are counteracted by risk. There is definitely some exaggeration and misinformation associated with the anti-fluoride argument which makes it relatively easy to dismiss any claims that align with that view, but it is important to keep an open mind and critically analyze data, regardless of how it relates to one’s own opinions or beliefs. The reality is that, as of now, the addition of the optimal concentration of fluoride to community water has not been shown to have any drastic negative impacts on human health. With that said, studies do show that exposure to levels of fluoride surpassing the maximum acceptable concentration does appear to have detrimental effects. Knowing this, it is understandable that there is concern surrounding the addition of any level of fluoride to drinking water, despite its failure to produce negative results, simply due to wariness of the mineral itself. The data accessible as of now does point toward community water fluoridation as being a positive movement for overall health, however the obscurity surrounding the topic comes from the uncertainty around the long term effects of persistent low level fluoride consumption. The unfavourable results of exposure to high levels of fluoride introduce fears and assumptions about the effects that proper community water fluoridation might have on Canadians later in life, after having been exposed to systemic fluoride for decades. This poses the question of whether or not it is wise to make public health decisions based on the lack of adverse effects presented by community water fluoridation thus far, along with its obvious benefits, or to make decisions based on potential risk that may or may not present in the future. In my personal opinion, the benefits of fluoride on the overall health of society today outweigh the presumptive effects that we may deal with in the future. The addition of the optimal concentration of fluoride to community water has no acute drawbacks, meanwhile, it possesses distinct benefits. I believe that the outcome most conducive to our society’s health and well-being is to make the educated decision to continue with the addition of fluoride to drinking water, keeping an open mind to the idea that, should any adverse repercussions occur in the future, the current policies on this topic may be subject to necessary adjustment.

REFERENCES

Green R, Lanphear B, Hornung R, Flora D, Martinez-Mier EA, Neufeld R, et al. Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada. JAMA Pediatr. 2019;173(10):940. Available from: https://www-ncbi-nlm-nih-gov.login.ezproxy.library.ualberta.ca/pmc/articles/PMC6704756/

Saeed M, Malik RN, Kamal A. Fluorosis and cognitive development among children (6-14 years of age) in the endemic areas of the world: a review and critical analysis. Environ Sci Pollut Res Int. 2020;27:2566–2579. Available from: https://link-springer-com.login.ezproxy.library.ualberta.ca/content/pdf/10.1007/s11356-019-06938-6.pdf 

National Center for Biotechnology Information. Community Water Fluoridation Exposure: A Review of Neurological and Cognitive Effects. 2019 [cited 2020 Apr 9]. Available from: https://www-ncbi-nlm-nih-gov.login.ezproxy.library.ualberta.ca/books/NBK551870/?report=reader#!po=0.980392  

Shaik N, Shanbhog R, Nandlal B, Tippeswamy HM. Fluoride and thyroid function in children resident of naturally fluoridated areas consuming different levels of fluoride in drinking water: An observational study. Contemp Clin Dent. 2019;10(1): 24–30. Available from: https://www-ncbi-nlm-nih-gov.login.ezproxy.library.ualberta.ca/pmc/articles/PMC6974988/  

 Luke J. Fluoride deposition in the aged human pineal gland. Karger. 2001;35:125–128. Available from: https://www-karger-com.login.ezproxy.library.ualberta.ca/Article/Abstract/47443 

Darby ML, Walsh MM, editors. Dental hygiene theory and practice. 3rd ed. St. Louis: Saunders/Elsevier; 2010. 

Srivastava S, Girones L, Oliva AL, Arias AH, Harrill AH, Sanders AP, et al. Fluoride in drinking water and skeletal fluorosis: a review of the global impact. Curr Environ Health Rep. 2020. https://doi.org/10.1007/s40572-020-00270-9 

8. Water-related diseases [Internet]. World Health Organization. World Health Organization; 2016 [cited 2020 Apr 9]. Available from: https://www.who.int/water_sanitation_health/diseases-risks/diseases/fluorosis/en/   

D.M. O’Mullane, R.J. Baez, S. Jones, M.A. Lennon, P.E. Petersen, A.J. Rugg- Gunn. Fluoride and oral health.Community Dent Health. 2016;33:69–99. Available from: https://www.who.int/water_sanitation_health/diseases-risks/diseases/fluorosis/en/  

 Ten Great Public Health Achievements -- United States, 1900-1999 [Internet]. Centers for Disease Control and Prevention. Centers for Disease Control and Prevention; [cited 2020 Apr 9]. Available from: https://www.cdc.gov/mmwr/preview/mmwrhtml/00056796.htm

 McLaren L, Patterson S, Thawer S, Faris P, McNeil D, Potestio M, et al. Measuring the short‐term impact of fluoridation cessation on dental caries in Grade 2 children using tooth surface indices. Community Dent Oral Epidemiol. 2016;44:274–282. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1111/cdoe.12215