If that were so, surely there would be plenty of examples to quote and health authorities would have moved quickly to stop its supply. On the contrary, those authorities are still doing their utmost to encourage communities to fluoridate.
Why? The evidence is clear and unarguable.
Fluoridated water does wonders for children's teeth. And, heaven knows, Rotorua children - whose dental health is among the worst in the land - deserve that boon.
Local health organisations have every right to claim that fluoridation would help to improve the dental health of the city's children.
And they are right, too, to point out that it would help to reduce inequalities in oral health, benefiting low-income, Maori and Pacific Islands children.
It is all very well to talk about providing fluoride tablets instead. The disadvantaged children who would benefit most are unlikely to be provided with tablets of any sort, let alone fluoride.
The great benefit of fluoridated water is that everybody drinks it and it costs nothing directly. Those - like me with my false teeth - who don't need it are absolutely unaffected, yet those who do need it receive great benefit.
One of the saddest letters so far was the one which declared: "We are only interested in Rotorua, not what is happening elsewhere in the country." Surely this sort of pathetic, parochial myopia is not common in our city. If it is, God help us.
Another letter-writer tries to tell us that fluoride is banned in 15 countries, including Israel.
Yet my information, from an impeccable source, is that in Israel water fluoridation is required for all communities of more than 5000 people.
I don't know about the rest of the countries he names, but if he is mistaken about one, then the rest are suspect.
Public water supplies have long been fluoridated in Australia and Britain; South Africa has made it mandatory for every water provider to include fluoride; in the United States fluoride is automatically introduced in all new community water supplies; and California has made it mandatory for all communities of more than 100,000.
I know that there's no getting through to some people, but I wonder about folk like the Fluoride Action Network national co-ordinator, Mary Byrne, who still insists, in spite of all the evidence that is right before their eyes, that "studies show" that fluoridation does not reduce dental decay and has serious side effects.
This is utter nonsense.
"Studies" these days come to all sorts of weird conclusions, usually depending on how much money is spent to get the desired result, but the fact remains that fluoridation has been found to be safe and effective by some of the world's most respected medical bodies.
In 1994, for instance, the World Health Organisation published a report reaffirming its support of fluoridation as safe and effective in preventing tooth decay.
Around the world more than 60 countries have fluoridated water supplies covering hundreds of millions of people.
So let's just get on and join them.
garth.george@hotmail.com