Fluoride can help strengthen baby teeth before they come through the gums by building fluoride into their structure. The main effect is when teeth erupt through the gums. If fluoride is present in saliva, teeth will continually be exposed to small levels of fluoride, which helps strengthen the tooth surface. Fluoridated water is the best way to achieve this.
top of page Is tooth decay a serious problem? Internationally, decay rates have been decreasing over the last 20 years. However, tooth decay is still a significant health problem, particularly in communities with insufficient fluoride in their water.
Tooth decay will result in the life-long repair of teeth or tooth loss. Decay causes pain and loss of self-esteem and it also costs individuals and the community to treat it. Approximately $500 million is spent in New Zealand on dental treatment. The largest proportion of this is treating dental decay.
Dental pain can stop a person from eating, working and sleeping which affects their whole wellbeing. Decayed teeth can affect people’s self-esteem and confidence about the way their teeth look or their bad breath.
Although tooth decay remains a common disease, it is largely preventable. Dental decay does not have to be a fact of life – prevention is possible and fluoridation, along with a healthy diet, is the most cost-effective way to achieve this.
Where else can I get fluoride from?
Common sources of fluoride for people include food and drink, toothpaste and fluoride supplements such as tablets.
Some countries use fluoridated salt, others fluoridated milk. The World Health Organization says fluoridated water is the most effective and safest way of providing the benefits of fluoride.
Go to information about sources of fluoride
top of page Do fluoride tablets work as well as fluoridated water?
No. The benefit of fluoride tablets is limited as they don’t provide constant small doses throughout the day and are more expensive over time than water fluoridation.
The fluoride in the saliva from a tablet lasts only three hours, and would give less than 1 percent of the fluoride available from food and drink in a fluoridated area.
To be effective, fluoride tablets must be taken every day and preferably chewed. Even well-motivated parents can find it difficult to ensure children receive tablets regularly. At a public research level, water fluoridation is more effective because it is taken regularly throughout the day in the water used to drink and cook with irrespective of the consumer's social, economic or physical status.
How do we know fluoridation is effective? The effectiveness of water fluoridation has been documented in scientific literature for well over 50 years. Data from the 1930s and 1940s shows that even before fluoridation, children drinking naturally fluoridated water had lower decay rates than children consuming water without fluoride.
Studies have also shown that when communities stop fluoridation, there is a reversal of the benefits, an increase in decay rates and a large increase in the number of baby teeth extracted.
It is true that over the years, decay rates have declined in both fluoridated and non-fluoridated areas. This can largely be explained by the use of fluoride toothpaste and the cross-over effects of food and water containing products from fluoridated areas. Most recent studies continue to show that the difference between fluoridated and non-fluoridated areas continues to be significant throughout life.
The World Health Organization has reviewed the data available and the Public Health Commission (PHC) in New Zealand published an extensive review of water fluoridation in 1994 and supports fluoridation.
In September 2000 the Ministry of Health released a report, written by Environmental Science and Research Ltd (ESR), evaluating recent evidence of the fluoridation of water supplies. This report provides further support for the safety and effectiveness of water fluoridation.
In 2003 the Public Health Advisory Committee (PHAC) also reviewed evidence of the effect of water fluoridation with respect to reducing inequalities in oral health. It strongly recommended increasing the proportion of the New Zealand population receiving fluoridated water.
top of page Does fluoridation cause health problems?
The weight of scientific evidence supporting the safety and effectiveness of fluoridation is overwhelming and it is clear the majority of reputable health, scientific and medical bodies agree with its use.
Many parts of the world have received naturally fluoridated water for thousands of years. Large human populations have now been exposed to community water fluoridation for many decades and no persuasive evidence links optimal fluoridation with any adverse health effects. With hundreds of millions of people continuing to receive the benefits of fluoride in drinking-water, the absence of documented adverse health effects is particularly convincing. Information about water fluoridation and safety Information about fluoride and health Can fluoridated water cause toxic effects?
It is impossible to experience fluoride toxicity from drinking-water optimally fluoridated at levels between 0.7 ppm to 1 ppm. It would require drinking more than 5000 glasses of fluoridated water at one time.
Anything is toxic if you take too much of it, including many common substances that are essential to health, for example, water, iron, vitamins A and D or even oxygen.
In excessive quantities fluoride too can be toxic, but, at the very low concentrations (0.7 ppm to 1 ppm) used in water fluoridation it is not toxic, even when used over a lifetime.
top of page Why do some communities not accept fluoridation? A community may not accept fluoridation for many reasons. Often a referendum is held where low voter turnouts are common and sometimes communities are not provided with accurate information. However, it is important to note that fluoridation has never been discontinued because it was proven harmful in any way.
Why does opposition to community water fluoridation continue?
A lot of opposition is based on the question of freedom of choice, which can be a very emotional issue. Some people feel very strongly that they should not have to receive fluoridated water if they do not wish to.
Society often makes decisions or rules based on the benefits to the community as a whole (for example, putting iodine in salt or wearing seat-belts). Some people believe that these decisions limit our personal choice. Public health organisations encourage communities to adopt fluoridation because the benefits to everyone with natural teeth are so worthwhile that the whole community should have access to those benefits.
The option remains for people who are particularly opposed to fluoride in the water to install a filter to remove it if they wish.
There is also evidence that several groups opposed to water fluoridation use ‘fear tactics’ to raise safety concerns within the community. No ‘scare claims’ are generalisable to water fluoridation at the recommended levels.
A very large body of scientific literature supports fluoridation as a safe means of reducing rates of tooth decay.
top of page What is the optimal level of fluoridated water a person should drink on a daily basis?
An estimated 75–90 percent of ingested fluoride is absorbed by the alimentary tract (NRC 1993). Fluoride in drinking-water accounts for about half of the total intake in young children and half the total intake in adults (NHMRC 1991).
The rest of the intake is from dietary sources, especially from tea, which contains fluoride in the range of 1 - 3 ppm (Murray et al 1991). Some heavy tea drinkers may even have intakes of 8 - 10 mg/day (refer to Water Fluoridation In New Zealand). Drinking-water with 0.7 - 1.2 ppm, together with a normal diet, provides safe and appropriate levels of fluoride intake.
What if people have health conditions like kidney disease? There is no research evidence of increased kidney disease or dysfunction in humans drinking up to 8 ppm fluoride; nor is there any evidence that existing kidney disease is made worse.
What if people use a fluoridated toothpaste as well, will that be too much fluoride? Studies show that water fluoridation provides benefits above and beyond those from other fluoride vehicles alone (for example, toothpaste or tablets). Conversely, fluoride toothpastes provide additional benefits beyond water fluoridation.
Water fluoridation is not a replacement for tooth brushing with fluoride toothpaste, as brushing helps to remove the bacteria (found in plaque) and keeps gums healthy. Rather, the two work hand in hand to help prevent tooth decay, and provide an additional benefit above that of fluoridated water alone.
top of page Can a person have too much fluoride in their body? Yes, in the same way that a person can have too many vitamins and other dietary supplements. In other parts of the world, where there are extremely high levels of fluoride, it can cause skeletal fluorosis. This requires the ingestion of much larger amounts of fluoride than anyone in New Zealand would be exposed to.
What is the benefit of fluoride to teeth when it is ingested instead of applied topically?
Fluoride ingested and applied topically, such as drinking-water and brushing teeth with a fluoridated toothpaste, go hand in hand as effective measures to help prevent tooth decay.
Sugar intake constantly flowing past teeth needs good levels of fluoride in plaque and saliva to be the ‘first line’ in tooth decay prevention.
Human beings are well adapted to living in an environment with natural fluoride. Some of the fluoride we ingest is taken up by bones and teeth. The fluoride taken in to the teeth also helps to prevent dental decay by strengthening the teeth and reducing enamel demineralisation.
Our kidneys excrete excessive fluoride from the body, so to protect teeth over our lifetime it is important to have small, regular amounts such as is provided in fluoridated water and fluoridated toothpaste.
When fluoride is ingested regularly when teeth are developing, it is deposited across the tooth's entire surface and this slows down decay. Because of this, tooth decay in fluoridated areas progresses more slowly.
Can the Minister of Health provide information that confirms the safety of hydrofluorosilicic acid? The most recent study is that commissioned by the City of Fort Collins, US. The Fluoride Technical Study Group found that adding hydrofluorosilicic acid did not increase any contaminants levels into the water quality so it was unlikely community water fluoridation poses a health risk’. Fluoride Technical Study Group report (www.healthdistrict.org)
top of page What is the difference (in any form of measurement) between a safe intake and potentially harmful intake of fluoride?
The Drinking-Water Standards for New Zealand focus on defining safety standards to prevent adverse health effects. The recommended maximum acceptable value (MAV) for fluoride is proposed as 1.5 mg/l. The guidelines also recommend the adjustment of water fluoride to between 0.7 mg/l and 1.0 mg/l for oral health reasons. Because the dosage is over half the MAV, this automatically makes the water supply a ‘priority 2’ under the standards. This means the supply must be monitored to demonstrate compliance with the standards.
top of page Page last reviewed: 6 August 2009
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