Thursday, 25 November 2010

Low EMF radiation not harmful to health, says WHO (but scores higher than secondary smoke)

Low level radiation from electro magnetic fields has not been found harmful to health, according to the World Health Organisation. So I am told by the Energy Directorate of the Scottish Government, following an enquiry regarding this post. My enquiry to Energy Secretary Jim Mather ran as follows:
In your capacity as Energy Minister I am interested in your views on how a power line can be authorised and not undergrounded in a heavily populated area, even though the relative risk of childhood leukaemia in areas close to high voltage power lines can be up to 4 (compared with relative risks of lung cancer and heart disease resulting from exposure to secondary smoke commonly given as 1.2–1.3, yet is held to be dangerous enough to justify a comprehensive smoking ban).
The reply indicated that Scottish Ministers can authorise or reject overhead lines, and they do not have authority in respect of putting lines underground. Further,
In respect of the health concerns, the Scottish Ministers take advice from the Health Protection Agency (HPA), and their view accords with that of the World Health Organisation – that despite extensive research, there is no evidence to conclude the exposure to low level Electro Magnetic Fields (EMF) is harmful to human health.
The writer of this letter made no allusion to risk levels from secondary smoke exposure.

The radiation off power lines shows at the bottom of the scale. But does this mean that the risks are non-existent? Not being an epidemiologist I am approaching this with considerable caution. The results I have found from this study in Canada give a relative risk from exposure to EMF of 1.72 (95% CI 0.54–5.45) and concluded no significant risk. From Germany, in pooled studies that included separate studies of night-time exposure, relative risks went up to 5.81 (95% CI 0.78–43.2 [is this an error?]).

Comparing the results with secondary smoke exposures: 1.4 (95% CI 0.9-2.2) for the total population and 1.2 (95% CI 0.7-2.1) (described by our good friend RT as a Killer Finding), it is clear that the risks for EMF score higher.

The letter from the Energy Directorate indicates that the situation regarding exposure to leukaemia from power lines will be carefully observed: clearly they diagnose the problem as lower than borderline significance. But then how do they (with World Health Organisation approval) get the whole world panicked about secondary smoke exposure, when it never seems to give a relative risk higher than about 1.4?


Anonymous said...

Haven't read it, but it is possible to have a RR of 5.81 and the CI including 1.0. One way this could happen is if the sample was very small.
More generally, the anti smoking industry would argue that although most of the results for passive smoking studies are not significant, when a meta analysis is conducted on all of them together, the result is significant. There are plenty of arguments against this, which will be rolled out should subsequent studies on power lines consistently point towards a risk.

Anonymous said...

Meta analysis can be used to show trends that are not immediately apparent from individual studies but its big weakness therefore is that it can also over emphasize trends that are very insignificant or non-existent.

It is obviously a very fashionable tool for those people pursuing policy based research who are desperate to see a specific outcome from data that stubbornly refuse to provide it but many real scientists are concerned that it is pretty close to voodoo and if you need to use meta analysis to show an effect it probably isn't all that important.

Most of the “new” studies we read about involve people simply re-hashing old work using this type of approach and if you feel the need to check out a bunch of loonies who think that it is the best thing ever try looking up The World Cancer Research Fund. Be very afraid.

Klaus K said...

Epidemiology shows that neither EMF or passive smoking can be a hazard to public health. Furthermore there is no plausible explanation to why EMF should cause leukemia. This is the main reason for why that theory is dismissed.

However a plausible explanation exists for why passive smoking could cause lung cancer, since active smoking is a risk factor of lung cancer, but this theory is threatened right now, because scientists have found that lung cancer in smokers and never-smokers may be two completely different diseases - and thus the theory cannot use the plausible-argument. Google: [lung cancer never smokers]

Regarding epidemiology in passive smoking, the British statistician Peter Lee has shown why passive smoking can be no cause of either lung cancer or heart disease, even if pooling of all published studies gives significant results:

Belinda said...

The difference between passive smoking and EMF is that you can find expressions of genuine public concern about EMF from people whose symptoms appear to result from exposure to it, whereas with passive smoking 99 per cent of complaints from the public are about the smell (or Roy Castle). There are complaints about other things than leukaemia too.