Doubt has been cast over theories that air pollution caused by overhead power lines is linked to the development of childhood leukaemia, researchers say today.
A study published in the Journal of Radiological Protection has found little evidence to support the ‘corona-ion hypothesis’, which has been cited as a possible reason for the number of childhood leukaemia cases recorded close to high-voltage overhead power lines in the UK before the 1980s.
But the cause behind the increased number of leukaemia cases remains unclear.
The hypothesis is based on the fact that high-voltage overhead power lines create charged particles in the surrounding air by ionisation. These ionised particles, known as corona ions, can attach themselves to air pollutants, which are more likely to be retained in the airways or lungs, thus leading to serious health effects, including childhood leukaemia.
Research by the Childhood Cancer Research Group at the University of Oxford and National Grid has demonstrated that on average there has been no increased risk of leukaemia among children born near high-voltage power lines in recent years.
However, the same piece of research confirmed an increased risk prior to the 1980s, which has yet to be explained.
Investigators from the Institute of Physics have used data from more than 7,000 children in England and Wales who were born and diagnosed with leukaemia between 1968 and 2008, and who lived within 600 metres of a high-voltage overhead power line.
They calculated the exposure of each of the children to corona ions using a model based on: the voltage of the power line; the distance from the line; how the concentration of corona ions varied with distance from the power lines; and the amount of time, and speed, that wind blew in each direction around the power lines.
The results did not reveal exposure to corona ions could explain the pattern of increased leukaemia rates close to high-voltage overhead power lines.
Kathryn Bunch, co-author of the study, said: “We found in earlier studies that, for previous decades, childhood leukaemia rates were higher near power lines. This new paper seems to show that this wasn’t caused by corona ions – but it leaves us still searching for the true cause and we are undertaking further investigations of the variation in risk over time.”
Swanson J et al. Childhood cancer and exposure to corona ions from power lines: an epidemiological test. 2014 J. Radiol. Prot. 34 873. [abstract]
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