There are at least two alternatives to scientific studies. One is to ignore the science and go straight for myth, magic and superstition. The other is to start with a scientific study and then twist it to suit your own purposes. This second appears regularly in the world of science and, unfortunately, is becoming more common.
Take the example of mercury amalgam fillings in teeth. In Britain and America a good proportion of the population has already got these ‘silver’ fillings, and it would be reassuring for them to know that there were no problems associated with such a procedure, even though it means having mercury (a known poison) in your mouth, often for many years. A recent study, we are told, says exactly that: we have nothing to worry about.
Let’s look at this Study. It came out in 2006 and involved a group of 1,000 school children, over a period of 3 years. Hmm, pretty impressive. However, there are several things to note. One is that the age range was 7-10 years old. That tells us something about these children, but there is no way to predict their future health. We can’t be sure what will happen to them from the ages of, say, 17-20 or 27-30, and we certainly can’t work out from this study what is happening to 27 year olds right now. In my case, I’m a good deal older, and I want to know what effect the fillings are having on the 47-50 year olds, or even the 57-60 year olds. Trying to extrapolate from this one Study to that age group is silly but, amazingly, that is exactly what some writers have done. One, a columnist in the Guardian newspaper in London, has tried to assert that this study is ‘reassuring’ for all age groups.
Worse, though the Study was limited to a small geographical area, the writer tries to say that the results apply to all school children, everywhere. Would you believe that? Young people in China and Japan have a completely different health profile to those in Europe. Why, there are studies that show children in the South of England have a different experience to those in the North of England. This writer ignores that. The Study shows these children are healthy, he says, therefore all children will be healthy. No, that’s Bad Science.
There’s more. If this Study looked at the children’s health, you might imagine that when they met up with the scientists conducting the work, (every two months, as it happens), the man in (or woman) in the white coat would be writing down facts about the child’s health on their clipboard. If the child said they had headaches, or infections, or sleepless nights, the information would be noted, right? Not a bit of it. The Study was focussed on neurological development, which meant, basically, three tests: one, was the application of IQ tests on a regular basis; the second area involved brain scans, MRI’s and stuff like that; the third topic was reaction times – You’ve tried ‘Whack the Rat’? They do it on computers these days, but the principle is the same: a light comes on and you have to hit a button. If you do it quickly you’re fine, if you’re slow, there might be something wrong. Well, that’s all good and it tells us something, but it’s bad news for parents; some want to know if amalgam ‘silver’ fillings are related to such childhood illnesses as asthma. The Study had nothing to say on that, because it didn’t look at it. If somebody said, ‘This report showed no link between amalgam fillings and the increase in asthma amongst young people’, it would be correct – but totally misleading. There is ‘no evidence’, in this case, because none was sought. Is there a link? We don’t know. We’re waiting for that study to be done.
There’s more. Think about kids aged 7 to 10. You’ve had them? Then what happens during those years? You’re right: their teeth fall out. The early ‘milk teeth’ are replaced by adult growth. Which means, unfortunately for the Study, that some of these children started the investigation with teeth that didn’t last. Those teeth might have had fillings in, but the teeth dropped out before the end of the 3 years. Worse, the new teeth that grew may or may not have required fillings during this period. Either way, very few of the children would have had fillings for all of the time scale; if a child defined as ‘with fillings’ only had them in for 3 months, 6 months, or a year of the study, that tells us nothing about the long-term effects of silver fillings. And, in particular, tells us nothing about an adult who’s had the same filling in their mouth for 20 or 30 years!
But there’s yet another problem. The Study set out to look at half the children having no fillings and half having some, (not many, as we see above), but even those with some, (and for a short period of time), weren’t found to be totally ‘healthy’, not completely! Even the journalist in the Guardian couldn’t claim that. He said that the differences between those with fillings and those without was ‘negligible’. Well, sorry, but my Dictionary defines negligible as ‘some’, a small amount, admittedly, but some. It might be a very, very small amount, say a couple of percent, which is fine, if you are reassured that when you’re told that, say, ‘90% of people are unaffected’ it automatically means that you’ll be in that group! Okay, it might be more than that: it might be 95% or even 97%, but that still leaves a small number with problems, possibly, and the reason that’s important is that you can’t confuse percentages with absolute numbers. 3% of the population might sound like a small number, but in a country the size of Britain, that’s 2 million people! If even half or a quarter of those were ill at any one time, the whole health system would be stressed to the point of collapse. In Britain we often have 100,000 people going down with flu every winter. If there’s 200,000 it’s officially classified as an ‘epidemic’. Imagine ten times that amount of people reporting to their doctors, or trying to find advice from their local hospital or clinic, or knocking on the doors of their dentists. The system couldn’t cope.
Well, you might say, that’s a bureaucratic problem, not a scientific one. Maybe that’s why some of us might suspect that the so-call ‘scientific’ evidence is being tampered with, or why public discussion is being stifled. Anyone who questions issues like mercury amalgam fillings is instantly labelled a ‘quack’ or some kind of Alternative Therapist. Such defensiveness is revealing, but unhelpful; it would be better if we could concentrate on the evidence and see what that has to tell us, without being misled by politicians, or journalists with an agenda. People who are, even know, using scientific studies for their own purposes.