Overhead power lines pose no cancer risk to children despite earlier fears of a link with leukaemia, a large study has found.
Scientists analysed data on almost 16,500 in the UK who were diagnosed with the blood cancer between 1962 and 2008.
They found no evidence that children born after the 1980s whose mothers lived within a kilometre of power lines had a greater than average risk of developing the disease.
A previous study focusing on leukaemia cases diagnosed between 1962 and 1995 had pointed to an increased risk for children born within 600 metres of the electric cables.
This strongly suggests that there is no direct biological effect from power lines that is helping to trigger childhood leukaemia, say the scientists.
They believe the earlier finding could be explained by changes in the characteristics of people living near power lines, pure chance, or problems with the study design.
Kathryn Bunch, from the Childhood Cancer Research Group at Oxford University, who led the new investigation, said: "It's very encouraging to see that in recent decades there has been no increased risk of leukaemia among children born near overhead power lines.
"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 leukaemia."
Results from the research, funded by the charity Children with Cancer UK, are reported in the British Journal of Cancer.
The scientists compared information from the National Registry of Childhood Tumours, which has stored data on nearly all children diagnosed with cancer in the UK since 1962, with records showing place of birth.
Leukaemia is the 11th most common cancer in the UK, but accounts for about a third of all cancers diagnosed in children.
Around 460 new cases of leukaemia are diagnosed in children under the age of 15 in the UK each year.
Dr Julie Sharp, head of health information at Cancer Research UK, which owns the British Journal of Cancer, said: "There has been a lot of concern that overhead power lines could increase the risk of cancer, particularly leukaemia, in children. This study is reassuring for anxious parents, as it indicates that overhead power lines don't cause leukaemia or other cancers in children."