It's Something in the Water

How can we move forward with the fluoridation debate? Hamilton City Council has an obligation to show that its decision will not cause harm

Fluoridation of public water supplies is a public health measure that has been around since the 1940s. Its benefit in reducing tooth decay in children and to a lesser extent in adults has long been established. Why then is it still being contested so fiercely in New Zealand and why did Hamilton City decide to stop it?

There seem to be three main reasons that might be headed roughly: ‘don’t mess with our water’;  ‘fluoride is poisonous’ and ‘we don’t need it’.

Don’t mess with our water. There is an objection to any intervention of this kind. It has elements of reason, emotion and politics. On the reason side is the knowledge that any attempt at improving on nature no matter how desirable its intention can have unforeseen consequences that are less desirable. The emotional element is the fear of alteration of what we eat and drink by forces that are outside our control and our understanding. The political element is the over-arching belief that individuals, not government, should take care of their health needs.

Fluoride is poisonous. There is the concern that fluoride may have toxic effects. A subset of this concern is the knowledge that there is a quantity of fluoride much larger than can be ingested from normally fluoridated water that is undoubtedly toxic and there is always the possibility, no matter how small, that such a quantity might accidentally be added to the water supply.[1]

Over the years, as researchers have investigated the properties of fluoride there have been papers published in reputable scientific journals raising questions as to whether fluoride ingestion in quantities obtainable from a fluoridated water supply is related to an increased risk of osteosarcoma, reduced IQ, skeletal fluorosis, dental fluorosis and no doubt other conditions.

We don’t need it. The third objection is that in modern times, since fluoride has been included in dental products such as toothpastes and mouthwashes, there is no longer a need for it to be added to the water. Research has shown some of these products to be effective in preventing tooth decay  

So why would you want to have fluoride in your water?

The ‘don’t mess with our water’ objections should be examined in the context of other public health measures. A broad definition of public health measures would include public access to the basic requirements for health; adequate nutrition, care, sanitation, exercise, shelter and clothing but let’s confine ourselves to interventions by authorities that deal with a specific issue. So, usually included would be: removal of lead from paint and petrol, iodisation of salt, and immunisation against poliomyelitis, meningococcal disease, measles and other infectious diseases. 

Provision of clean, potable water is a public health measure with historic significance. It was John Snow, a London physician and the father of epidemiology, who found that public water supplies were the source of the cholera epidemic in Soho in 1854. An apocryphal story has him removing the handles from the pumps on the contaminated wells, an early public health intervention. In any event the epidemic was brought to an end and an understanding gained of the importance of the quality of drinking water to health. The provision of a healthy water supply is now an elaborate process that is applied in cities and towns worldwide, usually under the direction of local authorities. Additives are required to deal with particulate, viral, bacterial and chemical contamination.

In the early days of fluoridation it had been found that some water supplies had natural fluoride in amounts that prevented tooth decay. Others did not and it was argued that authorities in these cities and towns had a responsibility to correct the deficiency.   

To the argument that fluoride is toxic in amounts that are ingested from fluoridated water supplies it can be said that no reputable research has so far been able to demonstrate that this is the case. Research that has raised the possibility of significant fluoride-produced toxic side effects, has so far been answered. An example is a possible association with increased risk of fractures.[2] The most recent is a Chinese study suggesting a lowering of IQ in populations drinking fluoridated water. It seems to be on the way to being resolved.[3],[4]

The argument that we no longer need fluoride in water because it’s in toothpaste and mouthwash clearly has validity although there are certain to be some children who will miss out because they don’t use these products. The question of how significant the difference is in a modern setting has been answered by at least one before-and-after study in an area that stopped fluoridation of its water supply. They found that the incidence of dental caries in ten-year-olds increased following cessation of fluoridation.[5]

My plea to the Hamilton City Council is to commit to an independent research project that compares rates of tooth decay before and after cessation of fluoridation. It’s the least they can do to meet their obligation to Hamilton’s children. The project should also include comparison of rates of any feared side-effect of fluoride ingestion, such as osteosarcoma. Such a study would provide valuable information on which the New Zealand public and local authorities might base decisions on what should be in their drinking water.  

[1] Gessner, B., Beller, M. (1994) Acute fluoride poisoning from a public water system. The New England Journal of Medicine, 330, 95-99.

[2] Rosen, C. (2000) Fluoride and fractures: An ecological fallacy. The Lancet, 355, 247-8.

[3] Sabour, S., Ghorbani, Z. (2013) Developmental fluoride neurotoxicity: Clinical importance versus statistical significance. Environmental Health Perspectives, 121(3), a70.

[4] Choi, A., Grandjean, P., Sun, G., Zhang, Y. (2013) Developmental fluoride neurotoxicity: Choi et al respond. Environmental Health Perspectives, 121(3), a70.

[5] Attwood, D., Blinkhorn, A. (1991) Dental health in schoolchildren 5 years after water fluoridation ceased in south-west Scotland. International Dental Journal, 41,1,43-8.