Fluoride is a naturally occurring substance in the earth's structure. Some communities have fluoride occurring naturally in their water supplies at levels that help to prevent cavities. Other communities adjust their fluoride levels. Fluoride is added to drinking water to help people have the best possible dental health. Since community water fluoridation began in 1945, it has been demonstrated to be a safe and cost-effective way to prevent tooth decay. Fluoridation of the drinking water is simply the precise adjustment of the naturally occurring fluoride levels in drinking water to optimal levels (0.5 - 0.8 mg/L) for the prevention of tooth decay. Fluoridation protects teeth in two ways:
Fluoride helps to prevent the tooth decay process and may actually reverse the tooth decay process at very early stages.
All natural water sources contain fluoride. Some water sources, (often deep wells) have a very high natural fluoride content which must be reduced before the water is delivered to consumers. London draws its water from Lakes Huron and Erie, which have relatively low fluoride levels. Controlled fluoridation raises the fluoride content to a more beneficial level for cavity prevention.
The City of London has been fluoridating its drinking water since 1967. The fluoridation of London's water supply was approved by a plebiscite (public vote) in 1966.
Fluoridation in London occurs by the addition of a compound known as Hydrofluorosilicic Acid (HFS), which dissociates (or dissolves) when added to the water, liberating fluoride ions.
The current source of London’s HFS is an ore that is mined and processed in Florida. This ore is rich in fluoride and phosphorus. Processing involves separating the fluoride and the phosphorus, creating HFS and Phosphoric Acid; an important ingredient in chemical fertilizer.
Any substance that is added to drinking water is required to pass rigorous testing to ensure that it meets the high standards that are legislated for the water industry. All HFS received by the City of London is independently tested to ensure that it meets the National Sanitation Foundation (NSF) and American National Standards Institute (ANSI) standards for purity. The NSF/ANSI Standards for fluoride products added to drinking water are even more stringent than the United States Pharmacopeia–National Formulary (USP-NF) Standards that apply to fluoride products used in pharmaceuticals.
Every element is toxic if consumed in very high dosages. For example, we need to breathe oxygen to survive, but high levels of oxygen are toxic. The natural impurities contained in HFS are found in extremely low concentrations and are not considered to be a threat to our health.
The Safe Drinking Water Act, 2002 (SDWA) governs the operation of municipal water systems in Ontario. Under this Act it is recommended that where fluoride is added, the concentration be adjusted to 0.5 - 0.8 mg/L, the optimum range for control of tooth decay. The City of London adjusts the fluoride level under the recommendation of the Director, Dental Services of the Middlesex-London Health Unit. The current recommendation is to target a fluoride concentration of 0.7 mg/L.