Extremely low-frequency non-ionizing radiation (ELF) is a natural component of environmental background radiation, but is also artificially produced by electrical devices. This low-level radiation is associated with electrical installations, transmission lines, home wiring, and electrical appliances such as computers, electric blankets, clocks and radios. Studies suggest it is the oscillating 60 hertz (cycles per second) current, (common to most electrical appliances), perhaps in combination with the background magnetic field of the earth, which produces radiation effects that can cause biochemical changes, interfering with function of genes and stimulating activity in biochemicals linked to the growth of cancer.
The magnetic field from the earth is 200 to 300 times as great as the level from power lines and appliances. Earth's magnetic field is about 450 milligauss in strength and fluctuates daily in response to solar activity and lunar motion. The amount of the fluctuation is roughly the same as magnetic fields from common house wiring, 1 to 5 milligauss. The magnetic fields suspected of causing childhood leukaemia are 3 to 4 milligauss, roughly one-hundredth the strength of the earth's static magnetic field. The strength of a magnetic field decreases rapidly with the distance from the source. At 2 centimetres, the magnetic field from the back of a microwave oven is 1,050 milligauss; at 40 centimetres it is 28 milligauss.
Thirty percent of the energy radiated from the aerial of a mobile telephone is absorbed directly into the brain of the user. Two research studies on the effects of exposure to EMR at frequencies similar to mobile telephone transmissions have shown it to cause DNA damage in the brains of rats. The US Food and Drink Administration advises users to use mobile telephones only when absolutely necessary and to make calls as brief as possible. US mobile telephone manufacturers were in 1995 already facing lawsuits claiming that their products have caused brain tumours.
In 1979, doctors at the University of Colorado reported that children exposed to higher than average magnetic fields had a twofold to threefold increased risk of leukaemia. Five subsequent epidemiological studies have reported similar findings, the latest in 1992 by the Swedish Karolinska Institute which studied a population of nearly half a million people living within 300 metres of power lines between 1960 and 1985; whereas a 1992 British government study and one by the Oak Ridge Associated Universities, USA, have concluded that the evidence to link low-level electric and magnetic fields with childhood cancers is too weak and inconsistent. In the USA, death rates as a result of breast cancer were reported in 1994 as 38 percent higher in women exposed to EMFs through job-related activities.