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For the record

Power lines and childhood asthma

On 2nd August 2011 the journal Archives of Pediatric and Adolescent Medicine published a study on the relationship between exposure of pregnant women to magnetic fields - from power lines and electrical appliances - and the risk of their children subsequently developing asthma. The Daily Mail ran an article with the headline ‘Pylons and hairdryers linked to baby asthma risk’.   

Here, Professor Patricia McKinney - Professor of Paediatric Epidemiology at the University of Leeds – and Prof David Spiegelhalter - Winton Professor of the Public Understanding of Risk at the University of Cambridge – explain the limitations of this research.

As Professor McKinney said: “The strong conclusions drawn from this paper that magnetic field exposure in pregnancy increases the risk of asthma in offspring cannot be justified based on the evidence provided in the publication. The investigation lacks a biological basis or hypothesis to test.”

 “Crucially we cannot determine how representative the sample was - an important factor in epidemiological studies as this selection bias may have been linked to mothers who were more heavily exposed to EMF or likely to have children with asthma. There are numerous additional well documented risk factors that remain unaccounted for. Childhood asthma is well researched and its cause is likely to be multifactorial, but this paper does not argue strongly for maternal exposure to EMF being a contributory factor.”

 Overall, Professor Speigelhalter said,  “this study has the advantage of having measured exposure to magnetic fields during pregnancy rather than relying on recall, but the disadvantage that the possible association with asthma seems to be an afterthought in a study of miscarriage”

NHS Behind the Headlines have written a piece looking at the weaknesses of this research in more detail.

Author: Sense About Science

Document type: For The Record

Published: 2 August 2011


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