It was quite a surprise. The report was prepared for the national radiological protection board. Stuart Allen, an NRPB expert who acted as consultant for the inquiry team, said he suspected mains supply lines to homes were involved, but could not be sure. Electromagnetic fields are measured in teslas. A high domestic exposure is consid ered to be an average 0.4 microteslas or more.
Household appliances generate much higher levels, but only at very short distances.
The combined effect of scores of electric motors and pumps in a home would not be enough to bring the average exposure to children up to 0.4 microteslas. Electromagnetic radiation in the home could be measured with a handheld device, but the NRPB said that, while more research was needed, it saw no reason to change guidelines in the wake of the report. Like the recent report on mobile phone radiation, the Doll group did not do field work, but collated results of nine projects around the world. They found exposure to more than 0.4 microteslas was associated with a doubling of the risk of leukaemia before age 15 from about one in 1,400 to one in 700. But the numbers of children involved were so tiny that it was hard to prove this was happening in Britain, and impossible as yet to prove that any increase was linked to electromagnetic fields.