Electric fields & ions

In 1996 and in 1999, the Bristol University Human Radiation Effects Group published papers suggesting that the electric fields from high-voltage overhead power lines might influence the behaviour of airborne particles in such a way as to be harmful to human health. The main example given was radon daughter products.

The suggestions made were:

• That electric fields make harmful particles from the atmosphere more likely to stick to the skin
  
• That electric fields increase the concentration of harmful particles in the atmosphere near the source of the field
  
• That power lines produce “corona ions” which make particles in the atmosphere more likely to stick in the lungs

The suggestions have not been widely accepted and there has been some controversy. The most recent independent view was published by the NRPB’s Advisory Group on Non-Ionising Radiation in 2004. They agree that most of the physical processes do happen, but conclude:

“…it seems unlikely that corona ions would have more than a small effect on the long-term health risks associated with particulate air pollutants, even in the individuals who are most affected. In public health terms, the proportionate impact will be even lower because only a small fraction of the general population live or work close to sources of corona ions.”

and

“Any health risks from the deposition of environmental particulate air pollutants on the skin appear to be negligible.”

In 2007 the WHO Environmental Health Criteria monograph echoed these words:

"High-voltage power lines produce clouds of electrically charged ions as a consequence of corona discharge. It is suggested that they could increase the deposition of airborne pollutants on the skin and on airways inside the body, possibly adversely affecting health. However, it seems unlikely that corona ions will have more than a small effect, if any, on longterm health risks, even in the individuals who are most exposed."

In 2005 the CCRG study looked at whether childhood cancer was more common downwind rather than upwind of power lines, as would be predicted by this suggestion. The paper says:

“We have made an initial test of this hypothesis using a simple model suggested by Preece et al (personal communication), assuming the prevailing wind is from the south west. The case-control ratio was no greater downwind than upwind of power lines, so, using this admittedly oversimplified approach, we have no evidence to support this hypothesis.”

You can read more about:

• The 2004 NRPB report
• Other statements by the NRPB on this issue
• Comments that have been made on the suggestions by electricity industry scientists
• The evidence on whether air pollution causes childhood cancer
• The evidence on whether radon causes skin cancer

Bristol University issued a response to the NRPB report at the time but it is no longer available on their web site.

A different group at the University of Bristol headed by Dr Preece is analysing the incidence of certain cancers in areas of Avon and the South West close to or downwind of powerlines. Various preliminary results were reported some time ago in the media and at scientific conferences, but the work is not yet finished, final results are not available, and the work has not been reported in the peer-reviewed scientific literature. There are various methodological issues raised by such work. Unless and until both the methods and the results are properly published it is not possible to assess the validity of the work or to place reliance on any results.

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