It is disturbing that, despite several letters of explanation, medical professional Dr Boyask (Letters, June 24/July 1) still fails to grasp the difference between water chlorination and water fluoridation.

It is the sole legitimate business of water companies to provide its customers with safe, drinkable, water. Chlorine is added solely for this purpose.

Fluoride is not added for this purpose but to treat dental conditions.

This deprives every person of their basic, legally protected right to choose or refuse medication and is neither the purpose nor right of water companies.

Dr Boyask states: "Fluoridation has been going on for millions of years and, as has been repeatedly stated and proven, where it is at correct levels it is dentally beneficial and otherwise harmless."

The National Pure Water Association (www.npwa.org.uk) states: "The fluoride added to water is 20-25 times more toxic than calcium fluoride, which occurs naturally in most waters".

Between 1987 and 1989, Parents of Fluoride Poisoned Children (PFPC) made a systematic survey of subclinical endemic cretinism in three areas of Xinjiang province, under a UNICEF Aid Project. It concluded: "The significant differences in IQ among these regions suggests fluoride can exacerbate central nervous lesions and somatic developmental disturbance caused by iodine deficiency", that "high fluoride intake can further disturb bone development" and there is "severe hearing loss in high fluoride and low iodine areas".

Of water fluoridation, they said: "How much longer is this fraud going to continue before we all do something to stop it, on a global level?"

Dr Boyask repeats claims for water fluoridation with no supporting evidence and despite other letters contradicting him. The "correct levels" cannot possibly be achieved this way, as everyone drinks different amounts of water and we are all exposed to other sources of fluoride.

-Gary Kemp, South East Against Fluoridation, Dover Road, Brighton