§ Mr. Lawrenceasked the Secretary of State for Social Services what is his assessment of the proportion of the population who would directly benefit from improved dental health if all the drinking water is fluoridated.
§ Mr. John PattenFluoridated water consumed from birth during the years of tooth formation— up to 14 years of age—gives the greatest dental health benefit. Research shows that this confers a measure of protection against tooth decay which persists throughout adult life. In consequence, the proportion of the population who would directly benefit if all drinking water were fluoridated would not be static but would increase year by year until the whole of the population had been covered. It remains, however, the Government's policy that decisions on the introduction of fluoridation schemes should be taken at local rather than national level.
§ Mr. Lawrenceasked the Secretary of State for Social Services what is his assessment of the maximum safe dose of fluoride in the body injected from any source.
§ Mr. John PattenSerious acute fluoride poisoning requires a single ingestion of at least 20 mg. of sodium fluoride per kg. body weight —1.2 g. for an average adult. The other main danger associated with chronic fluoride ingestion is skeletal fluorosis. Advanced skeletal fluorosis requires an ingestion of at least 20 mg. of fluoride ion per day for 10–20 years. Changes in bone density may be apparent on x-ray at lower doses but no such changes have been found in temperate climates where the levels of fluoride ion in drinking water have been less than 4 mg. per litre and there is evidence that the threshold for these changes is higher.
§ Mr. Lawrenceasked the Secretary of State for Social Services if he will estimate the total dose of fluoride that each individual will be receiving if fluoride is added to the public drinking water at one part per million.
§ Mr. John PattenIt is estimated that individuals consuming representative United Kingdom diets and average quantities of water containing fluoride at one part per million will ingest an average of 2.9 mg. of fluoride per day. The quantity will vary according to the composition of the diet and heavy tea drinkers, for example, will continue to derive substantially the greatest proportion of their daily intake from tea leaves, one of the natural sources of fluoride.