Watchdog calls for study of cancer link to power lines

New studies are needed to establish if weak magnetic fields from high-voltage power lines lead to childhood leukaemia, the Government's radiation watchdog said yesterday.

New studies are needed to establish if weak magnetic fields from high-voltage power lines lead to childhood leukaemia, the Government's radiation watchdog said yesterday.

The recommendations, by the National Radiological Protection Board (NRPB), follow international studies which suggest that continued exposure to low-level fields could double the risk of leukaemia for children exposed to it from one in 20,000 to one in 10,000 - and thus cause on average one or two extra cases of the blood cancer in the UK each year. There are about 500 cases annually.

A review of evidence from around the world suggests that the risk occurs with long-term exposure to magnetic fields above 0.4 microteslas - equivalent to standing about 60 metres from a high-voltage distribution line. Standing directly below a 400 kilowatt power line might expose a person to levels as high as 40 microteslas, but the dose diminishes rapidly as distance from the source increases. Roughly 0.5 per cent of the British population, or 300,000 people, are estimated to live in houses that might be exposed to at least 0.4 microteslas over a long period. By comparison a fridge magnet generates a field of about 0.1 tesla at its surface, but it is static.

The NRPB is urging investigation of fields that are 250,000 times weaker, but which change direction 50 times per second with the mains current.

But the NRPB emphasised that the evidence for any link with illness was patchy and inconclusive: a 1999 study, the UK Childhood Cancer Study, which sought possible causes of childhood leukaemia, found no link with magnetic fields.

Dr Alastair McKinlay, head of the NRPB's physical dosimetry department, said: "The NRPB considers this evidence related to cancer and EMF [electromagnetic fields] cannot be used to devise quantitative restrictions on exposure, but it certainly should not be ignored."