After years of controversy, a new study confirms that exposure to electromagnetic fields doubles leukaemia risks. Dr. Mae-Wan Ho reports.
The radiation emitted by power cables, pylons and electrical appliances in the home may be causing cancer in two children in Britain every year, according to new epidemiological evidence.
The study, commissioned by the National Radiological Protection Board (NRPB) concluded that one in 200 British children are exposed to high levels of electromagnetic radiation in the home and that this could be doubling their risk of leukaemia.
Dispute over the possible links between electromagnetic fields and cancer goes back to the 1970s in the United States and before. A series of laboratory and epidemiological investigations worldwide came up with contradictory and inconclusive findings.
But the argument has dramatically shifted in favour of there being a causal link with the publication in March 2002 of the long-awaited report by a team of scientists headed by Richard Doll of the Cancer Studies Unit at Oxford. Doll is renowned for his role in proving that smoking is the principal cause of lung cancer.
The danger occurs with exposures to electromagnetic fields of 0.4 microTeslas (or 4 milliGauss) and greater, levels that the NRPB says one in 200 children in Britain - and many abroad - receive in their houses.
For comparison, the earths magnetic field is about 50 microTeslas. The earths field, which includes other natural frequencies, has been with us since life began. And many organisms are adapted to it. Birds, for example, use the earths magnetic field to navigate long distances in their annual migration.
Since the discovery of electricity and the invention of radar in the 1930s, human beings have been saturating our everyday environment with a spectrum of artificial electromagnetic radiations (see Box 1), the harmful effects of which have become increasingly apparent.
Electromagnetic waves and the electromagnetic spectrum
Electromagnetic waves propagate through empty space at the speed of light, ie, 300 000 kilometres per second, and include the light that enables us to see, which vibrate at frequencies of about 1014 cycles per second. They have both an electrical component and a magnetic component vibrating at right angles to each another.
The entire electromagnetic spectrum is extremely wide, ranging from waves that vibrate at less than one cycle per second, or one Hz (Hertz) named after Heinrich Hertz, the German physicist who discovered electromagnetic waves in 1888 to 1024 Hz. The corresponding range of wavelengths speed/frequency is from 3 x 108 metres to 3 x 10-15 metre.
Above the visible spectrum are the ultraviolet rays, X-rays and g-rays, the ionising radiations that break molecules up into electrically charged entities, and can damage DNA, causing harmful mutations.
Below the visible spectrum, are the non-ionising electromagnetic radiation (NIEMR), emitted by electrical power stations, transmission lines, radio and TV towers, mobile phone base-stations, microwave ovens, radar, electric blankets, radios, TVs, computers, mobile phones, and other electrical appliances.
The report reveals for the first time that less than half of the exposures are due to nearby high-voltage power lines and electricity sub-stations. The remainder are probably from a combination of wiring, computers, televisions and other electrical equipment, but needs further research.
The effect is too small to have been detected in the UK Childhood Cancer Study conducted in 1999.
However it was spotted in a pooled analysis of 3,247 cases of childhood leukemia in Europe, North America and New Zealand published last year.
The report stops short of drawing any firm conclusions because of the absence of any proven biological mechanisms by which such low levels of non-ionising electromagnetic radiation can trigger cancer.
Source: "Electrical connection" by Rob Edwards and Duncan Graham-Rowe. New Scientist 6 March 2002.