New research published recently in the Journal of Radiological Protection has cast doubt on the ‘corona-ion hypothesis’. This theory had indicated that children living close to high-voltage overhead power lines were at increased risk of developing childhood leukemia and that this increased risk was due to changes in surrounding air pollution composition.
Childhood leukemia is responsible for approximately one third of cancers diagnosed in children, making it the most common form. Approximately 460 children under the age of 15 years are diagnosed with leukemia each year in the UK.
The research was a collaborative effort between the Childhood Cancer Research Group at the University of Oxford and National Grid (both UK). The investigators report that they discovered very little evidence that indicated the ‘corona-ion hypothesis’ was the cause of the spike in childhood leukemia cases in close proximity to high-voltage overhead power lines prior to 1980 in the UK.
The ’corona-ion hypothesis’ gains its name from the ionization of particles in the air close to high-voltage overhead power lines, a process that creates corona ions. It is postulated that these ionized particles can occasionally be transported by the wind and attach to air pollutants, such as those arising from smoking and traffic. The hypothesis suggests that these ionized pollutants have an increased likelihood of being retained in an individual’s lungs or airways and could result in leukemia.
Previous studies by the researchers have demonstrated that on average there is no increased risk of leukemia among children born near power lines in recent decades. However, prior to the 1980s, the same research confirmed an increased risk of childhood leukemia, which is still to be explained.
In order to investigate this theory, the research team utilized data from over 7000 children in England and Wales who were born and diagnosed with leukemia between 1968 and 2008, and who lived within 600m of a high-voltage overhead power line.
A complex model allowed the researchers to calculate the exposure of each person to corona ions. The model was based on the voltage of the power line, the distance from the line, how the concentration of ions varied with distance from the line, and the wind speed and direction around the power lines.
The results of the modeling process did not support the theory that exposure to corona ions explained the trend of increased leukemia cases close to high-voltage power lines found in earlier decades.
Co-author of the study Kathryn Bunch commented: “We found in earlier studies that, for previous decades, childhood leukemia 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.”