Research has shown unusually high levels of mercury in people who have died in recent years. This hasn't come to light before, because it's not 'mercury poisoning' that is written on the Death Certificate. It could be stroke, or heart attack, or embolism. These are the biggest killers in terms of numbers, but the question for many researchers has been, How was the health of these people in the few years before they died? Were they very healthy? Increasingly, the evidence shows that people who appear to have died from a supposedly simple cause, have, in fact, been suffering a range of illnesses and distressing symptoms over a long time. These range from depression, to memory loss, to lack of sleep and low energy levels. Often they are vague and hard to pin down, such as 'metallic taste in the mouth', lethargy and no urge to socialise. The first of these is the clue. Why would people taste metal? The only metal most people in the West have anywhere near their mouths is mercury, the basis of amalgam fillings.

Residents of Europe and the U.S. have got used to the idea that it's a good idea to fill their mouths with metal, yet this is a relatively recent invention. It only goes back to the Victorian age, or the end of the nineteenth century. It then became increasingly popular and became the 'norm' after the Second World War. Perhaps because of the trend for children to eat more sweets, chocolate and cakes once wartime rationing had been phased out, there was a huge increase in the number of cavities suffered by young people. The answer from dentists was to drill out the decay and fill the resulting hole with an amalgam of metal which composed 50% mercury. This was considered to be the hardest substitute known for tooth enamel, and certainly seemed to serve the purpose. Many people born in the 1940s and 1950s will have a large proportion of filled teeth, with hardly any complete and untouched. Only in the last few years has another trend emerged, of using white coloured resin, and usually this has been restricted to the front teeth, where it shows. Dentists, it seems, prefer the hardness of the metal and continue to use it regularly, particularly for the back teeth, partly because it is a cheaper option.

It will come as some surprise to Westerners then, to hear that this totally acceptable feature of our modern life is actually quite new in human history and quite rare in terms of the rest of the world. If there was a problem with practice, then, it would have only been apparent comparatively recently, and only in the countries of the world that use this method of preserving teeth. It's no good asserting that millions of people have mercury-based fillings and it's not doing them any harm. If it was, it might only be now that we would notice. Of course, if it's not on the Death Certificate as a cause of death, then it would be harder to notice. That's similar to Alzheimer's Disease and other dementias. The growth in these diseases has been alarming many researchers, but it is rare to see it given as a cause of death. Usually dementia sufferers become weakened and succumb to other illnesses, such as pneumonia. The figures therefore show that the disease is prevalent and distressing for many individuals and families, but it doesn't appear 'fatal'. That's simply playing with words. Dementias never get better. People who suffer from them, have them until they die. Once you've got it, you never recover. Why shouldn't we think of it as a 'terminal' illness?

The problem, for researchers into the effects of mercury on the body, is that they think they've found a link between dementias and mercury fillings. This is a contentious claim, and it's easy to play 'Top Trumps' with the research findings – you may prefer an established name and respected institution and the research they do, to some of the less formal and less well known studies. Of course, that's not how science works. If a link has been found, then it should be provable in differing settings and with different populations. That research has yet to be done, but there is something that is holding it up. Science is not, as we might expect, totally disinterested and balanced in its view of what needs to be looked into. The fact that research on the effects of mercury needs to be done is not the most important consideration for some academic bodies. They ask, What is the point? Suppose, for example, that it could be proved that there was a link between the mercury in teeth fillings and illness – of any kind – what impact would that have on society? In litigious cultures, such as the U.S.A., it might result in multi-million dollar lawsuits. It might also result in a complete collapse in confidence in the dental profession in the West, the one that has been using mercury amalgam for this generation with such frequency and assurance. It's a well-paid and prestigious career, with good connections to the political and economic elites. How likely is it that these professionals would be prepared to admit that their treatments are misguided and potentially dangerous?

It's an irony to think that the Baby Boomer generation might find themselves dying in swathes not from misuse of illegal drugs, self-indulgent living, or 'sex and drugs and rock and roll', but from the simplest of things – a metal they have been carrying around in their lives since early childhood. Of course, such thoughts may be misguided. Perhaps new research will confirm the industry's confidence that mercury amalgam is a completely inert substance that has none of the poisonous qualities of its major component – mercury, one of the most poisonous metals known, and one that if taken orally is completely and horribly fatal. After all, we now know that the first Emperor of China was smitten with the look, feel and qualities of mercury, so much so that he took small quantities of the liquid metal for his health. It killed him. There's no dispute about that. The argument, from modern dentists and their supporters, is that once the mercury is mixed with its other components, it becomes completely harmless. That is the claim being examined by recent research.

It's worth remembering that this isn't the only debate about the use of metals that has gone on in human history. The Romans used to line their aqueducts with lead to bring water into the city in the first few centuries of this era. We now know that people who drink water flowing across such metal can suffer from many illnesses, including brain damage in children. The Romans didn't know this, but it may be one reason for the decline of their culture. The question many observers are asking is, have we a similar problem here, and is it worth more effort being put into considering the possible problems before more damage is done?