Both the "pros" and the "antis" in the flouride debate are missing the full picture.

The scientific facts are straightforward. Fluoride is an essential trace element, and, as Dr Boyask says (Letters, April 20), is needed for the development of sound teeth.

It is also a potent toxin, as was found downwind of aluminium smelters in North Wales, and in the Bedford area, where there were brickworks using clay containing animal remains.

Cattle and trees were badly affected over a wide area. The trouble with putting flouride in the water supply is that it is not an efficient way of getting people to consume the right amount at the right time.

Adults gain no benefit, while the amount of water people drink varies between individuals.

It also occurs naturally in some foods, such as tea, and some methods of cooking involve boiling down the water, which will concentrate everything in it, including any fluoride compounds.

Those who drink a lot of tea or make soups could end up consuming a lot more fluoride than is good for them.

Since 98 per cent of all water is not drunk but used for washing or flushed down the toilet, putting fluoride in the water supply is a very wasteful method of delivery which also releases it indiscriminately into the general environment.

It should be offered as a dietary supplement, then it is up to parents to decide whether to give it to their children.

If the aim is to reduce tooth decay, priority should be given to discouraging children from eating the foods which cause it.

-Henry Law, Brighton