The increased risk of leukemia reported among children born close to overhead power lines is likely not a result of alterations in air pollution, researchers have reported in the Journal of Radiological Protection.
The group found little evidence to support the “corona-ion hypothesis” which has been cited as a possible explanation for the excess of childhood leukemia cases close to high-voltage overhead power lines in the UK prior to the 1980s.
The hypothesis is based on the fact that high-voltage overhead power lines create charged particles in the surrounding air.
These ionized particles, known as corona ions, can be blown away by the wind and attach to air pollutants, such as those from traffic or smoking.
The corona-ion hypothesis suggests these electrically charged pollutants are more likely to be retained in the airways or lungs, and this could lead to serious health effects, including childhood leukemia.
The researchers previously showed that, on average, there has been no increased risk of leukemia among children born near high-voltage power lines in recent decades. However, the same piece of research confirmed an increased risk prior to the 1980s, which has yet to be explained.
To investigate this theory, John Swanson, of National Grid in London, and his colleagues used data from 7347 children in England and Wales who were born and diagnosed with leukemia between 1968 and 2008, and who lived within 600 m of a high-voltage overhead power line.
The researchers calculated the exposure of each of the subjects 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, using data from various meteorological stations, the amount of time and speed that wind blew in each direction around the power lines.
The results did not suggest that exposure to corona ions explained the pattern of increased leukemia rates close to high-voltage overhead power lines previously found in earlier decades.
“We found in earlier studies that, for previous decades, childhood leukemia rates were higher near power lines,” said Kathryn Bunch, of the University of Oxford.
“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.”
