Living near overhead power lines in early life does not increase a child’s risk of developing leukemia, according to a study published in the British Journal of Cancer.
An earlier study using information on childhood leukemia diagnosed between 1962 and 1995 suggested there was an elevated risk for children born within 600 meters of overhead power lines.
But now, updated data indicate that children born after the 1980s don’t have an increased risk.
According to researchers, this strongly suggests there is no direct biological effect of power lines on leukemia risk.
They believe the previous findings could be explained by changes in the characteristics of people living near power lines. The results might also be a chance finding or have resulted from problems with the study design.
“It’s very encouraging to see that, in recent decades, there has been no increased risk of leukemia among children born near overhead power lines,” said lead study author Kathryn Bunch, of the University of Oxford.
“More research is needed to determine precisely why previous evidence suggested a risk prior to 1980, but parents can be reassured from the findings of this study that overhead power lines don’t increase their child’s risk of leukemia.”
Expanding on previous findings
Several years ago, Dr Bunch’s colleagues at the University of Oxford set out to determine if proximity to high-voltage power lines affected the risk of childhood cancers in England and Wales, using data spanning the period from 1962 to 1995.
The team found evidence to suggest a relationship between childhood leukemia risk and the proximity to power lines of the mother’s residence at the time of the child’s birth. This included all 400 kV and 275 kV power lines and a small fraction of 132 kV lines (Draper et al, BMJ 2005).
Dr Bunch and her colleagues decided to extend this study by including more recent data, as well as cases and control subjects from Scotland. The group evaluated 132 kV, 275 kV, and 400 kV power lines and looked at subjects living greater distances from the power lines than those included in the previous study.
The researchers analyzed 53,515 children enrolled in the National Registry of Childhood Tumours from 1962 to 2008 and a group of matched controls.
The team found that, for the entire study period, there was no evidence of an increased risk of leukemia among subjects living closer to power lines. The relative risk of leukemia for children living 0 m to 199 m from power lines, compared with those living 1000 m or more from power lines (for all voltages), was 1.12.
There did appear to be an increased risk of leukemia when the researchers analyzed data according to decade. However, this risk declined over time.
The relative risk of leukemia for children living 0 m to 199 m from power lines, compared with those living 1000 m or more from power lines, was 4.50 in the 1960s, 2.46 in the 1970s, 1.54 in the 1980s, 0.99 in the 1990s, and 0.71 in the 2000s.
The elevated risk in the 1980s was not statistically significant, the researchers noted. They also pointed out that, even in the decades when the risk appears to be present, there is no evidence that it extended beyond the 600 m limit of the original analysis.
The fact that the risk declined over time suggests the leukemia is unlikely to have arisen from any physical effect of the power lines, the researchers said. They believe it’s more likely the result of changing population characteristics.
