The Essex town of Maldon was once well known to dentists, because natural deposits of fluorine salts in local springs meant that the inhabitants had teeth that were strong, if somewhat brown. But while Maldon was a textbook example of the beneficial effects of fluoride at low levels, events in Nadvoitsi, a town in the former Soviet Union, show what happens when intake becomes excessive. Just 125 miles south of the Arctic Circle, Nadvoitsi is home to a huge aluminium factory that belches fumes night and day. But although aerial pollution causes liver disease, it is the children's teeth that tell the real horror story.
From the age of three, most young mouths here are filled with splintered, blackened stumps. And when the milk teeth drop out, they are replaced with yet more decaying teeth, that become so brittle they have been known to break off just biting on a peanut. The cause is a disease called fluorosis, or fluoride poisoning. And in Nadvoitsi, it is no secret where the contaminant comes from.
Faced with increasing demands for aluminium in the 1960s, directors of the factory, which employs 90 per cent of workers in the town, dumped bricks saturated with fluorine salts into a nearby swamp. From there, it gradually made its way into the lake which provides the town with its drinking water, and for the past 15 years it has been poisoning the inhabitants.
Children are more sensitive than adults to the disease, which also damages internal organs and slowly destroys bones. Recent estimates suggest that 93 per cent of young people in the town are now affected, 84 per cent of them severely.
For years, the authorities denied that pollution was the cause, blaming the symptoms on excessive tea consumption. But five years ago, the Green Party established the true cause, and since then, official denials have been replaced by official reassurances that the situation is under control.
However, in a town where people over the age of 15 automatically put their hands to their mouths whenever they speak, nobody is smiling yet.