New evidence that power lines do not cause childhood leukaemia
While most research has yielded no evidence of a link between the magnetic fields and childhood cancer, some uncertainty still remains over the safety of a minority of homes with very high levels of exposure.
But the new research, from the National Radiological Protection Board in Oxfordshire, has found no evidence that exposure, even to very strong magnetic fields, could lead to cancer.
Large-scale studies looking at disease trends have suggested a link between extremely low frequency (ELF) electromagnetic fields - which result from everyday sources such as overhead power lines and household appliances - and slight increased risk of childhood leukaemia, but only in homes with prolonged exposure to unusually strong magnetic fields. Such levels are present in only 0.5 per cent of UK homes.
The magnetic fields do not themselves have enough energy to directly cause damage to DNA that can lead to cancer. But the new research examined a theory that the magnetic fields might somehow prevent cells from repairing everyday DNA damage.
The researchers set up conditions in the lab to see if they could create this effect using blood cells from a donor, and found no evidence that magnetic fields damage the normal repair process in human cells.
The team was able to create cancer-causing damage to the cells by blasting them with radiation. The cells repaired themselves naturally, even while subjected to magnetic fields stronger than those experienced in British homes.
Lead researcher Dr David Lloyd says: "Some studies in the past have thrown up evidence of a weak link between unusually strong magnetic fields experienced in some homes, and leukaemia in children. We tried to produce this effect in cells in the lab, but couldn't find it even using magnetic fields stronger than people would experience in everyday life."
The new result adds weight to a growing consensus that magnetic fields are not a cause of leukaemia in children.
Dr Lloyd says: "Studies like ours have so far failed to uncover a pathway by which magnetic fields could cause childhood leukaemia - and it's looking probable that none exists."
Cancer Research UK's Sir Paul Nurse says: "We know environmental factors play a part in cancer, but it can be difficult to pinpoint all of them. Where large population studies throw up possible links to cancer, such as this, it is very important to investigate the link fully to see if it really exists.
"Many people have been concerned that the electromagnetic fields we are exposed to on a daily basis may have an impact on our health. The result of this study contributes to allaying those fears."
- British Journal of Cancer88 (12)
Notes to Editor
Cancer Research UK is Europe's largest cancer charity and owns the British Journal of Cancer.
The scientists used a well-established test as a means of assessing DNA damage and repair in cells. The technique involves counting the number of abnormal chromosomes present in a cell before it divides to form two cells.
The same technique is used to check people for genetic damage after accidents such as Chernobyl - damage that is frequently manifested as an unusually high number of chromosomes. It is also used to check for potentially dangerous effects of new drugs while they are under trial.
The research was funded by the EMF Biological Research Trust.