Tuesday, May 8, 2012

Frightening Fact 3: People ignore warnings when it suits them

Take the case of Alice Stewart, who in the 1950s tried to discover why young children were being increasingly threatened by an certain kind of leukaemia.

She and her team visited all 203 public health departments around Britain to obtain details of every child who had died of leukaemia between 1953 and 1955. As part of the survey, a questionnaire was sent to the mothers of these children as well as to the mothers of children in two control groups - children who had died of other cancers, and children who were alive and well. The interviews with mothers covered topics including consumption of various food items, maternal age, birth rank and social class, pregnancy illnesses, drugs, x-rays; postnatal infections, inoculations, parent's occupations, family histories of cancer.

What she found in 1958 was evidence that foetal irradiation was a major cause. X-rays were associated with about one child death per week.

But, what was the reaction? The official line was that there was a threshold beneath which x-rays were safe. Alice Stewart's results were viewed with scepticism. Her funding was cut. Doctors went on x-raying pregnant women right into the 1980s, even though it doubled the chance of a childhood cancer. It took a long time for Alice Stewart's work to be proved true.

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So, yes, it's right for people to be able to challenge received wisdom, and sometimes such challenges are wrongly ignored.

But how does this compare with our case, the case of microwaves?

Remember firstly that Alice Stewart found results that were instantly recognisable from her survey - a very clear link. Studies into microwaves have found no clear link to ill health.

And the reason why is obvious from a little scientific background.

The energy of an x-ray photon is in the region of 120 keV.

The energy of a microwave photon is in the region of 120 µeV.

That first unit is a kilo electron volt. Kilo = a thousand. The second unit is a micro electron volt. Micro = a millionth. So we have a difference in order of magnitude of a billion.

What can we compare that to? Lets say a whale at 200 tonnes and some plankton at 0.2 grams. They have a difference in order of magnitude of a billion too. Yes the x-ray photon is like a whale and the microwave is like the plankton. One you wouldn't notice if it swam against you. The other would be more dramatic.

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