So now The Lancet has got me really irked. Scientists, particularly epidemiologists, are fond of pointing out how the general public has such a poor understanding of statistics and science. And it’s a fair criticism; witness the hysteria over mad cows or the MMR jab (I personally think an interpretation of statistics course should be compulsory in any democracy). Anyway, the public can’t be blamed when scientists themselves are brazen in their claims to the point where they are accused by other scientists of scaremongering.
Ths has been the situation over a press release by the Harvard School of Public Health which itself refers to, yes, another Lancet study on the dangers of industrial chemicals to children. Here is the opening para of the press release:
Boston, MA – Fetal and early childhood exposures to industrial chemicals in the environment can damage the developing brain and can lead to neurodevelopmental disorders (NDDs)—autism, attention deficit disorder (ADHD), and mental retardation. Still, there has been insufficient research done to identify the individual chemicals that can cause injury to the developing brains of children.
n a new review study…The researchers found that 202 industrial chemicals have the capacity to damage the human brain, and they conclude that chemical pollution may have harmed the brains of millions of children worldwide. The authors conclude further that the toxic effects of industrial chemicals on children have generally been overlooked.
And here are two quotes from the paper:
the combined evidence suggests that neuro-developmental disorders caused by industrial chemicals has created a silent pandemic
And then later,
Although these chemicals might have caused impaired brain development in millions of children, the profound effects of such a pandemic are not apparent from available statistics
Confused? You should be.
Now, I kind of know what they’re trying to say: we know chemicals can harm children, so it’s probably a good idea to screen other chemicals for these effects. But look at what they actually say: some chemicals have proven to have harmful effects on child development and because there are lots of chemicals that aren’t tested, then these may also be having a harmful and very widespread effect. Panicked? Well, I’m too rational, even for an expectant father, to be worried by such a claim, and also not so stupid that I’ll take it in, especially after reading this in the Telegraph
Prof Nigel Brown, of St George’s, University of London, said: “It is possible that there is a problem, we should be aware of this and we should study the problem, but there is currently not a shred of evidence of a pandemic.
This is a campaigning article and should be treated as such. The campaign is worthwhile. However, in their enthusiasm, the authors verge on scaremongering. There is nothing new here; no original insights or concepts.t is a review only in the most superficial sense. There are no meta analyses; no considerations of mechanisms; no calculations of minimal toxic concentrations; no discussion of actual human exposure levels. These are, of course, difficult issues, but that is no excuse for ignoring them.
In other words, respected scientists have let their own agenda subvert their objectivity and in the process perhaps created mild panic. Even worse, they may have convinced public health authorities to screen for all sorts of chemicals. Now I’m not against sensible precautions in general, but I’d prefer them to be weighed up against the risks of not taking action. I don’t even have a thing against campaigning science articles, so long as the issue is discussed in a responsible way. But it does annoy me when the writers give little consideration to how their work will be interpreted by the public. A public that finds science difficult and a turn-off, makes lapses in probability judgements and perhaps most devastating, expects “somebody” to pay for a risk that may not even materialise.
And to think, only the other day I defended that damned Lancet and that study.
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