Questions and Answers About EMF Electric and Magnetic Fields Associated with the Use of Electrical Power.
January 1995.

Your EMF Environment

Q. Is there something significant about the 2-mG magnetic field level?

A. The significance of 2 mG is as a boundary to define the exposed group in some studies, not as a safety threshold. Some experiments with cells hvae reported effects at field levels as low as 2 mG but there is nolaboratory evidence for adverse human health effects at this level.

A typical American home has a background magnetic field level (away from any appliances) that ranges from 0.5 mG to 4 mG, with an average value of 0.9 mG.* Most ordinary electrical appliances produce higher localized magnetic fields.

Several EMF epidemiological studies have used 2 or 3 mG as a cut-off point to define broad categories of exposure. Below this level, subjects are considered "unexposed," and above this level they are considered "exposed." In some studies, a higher cancer risk was , found within the exposed group. Other studies found no such increased risk. The significance of 2 mG as a boundary to define the exposed group in some studies, not as a safety threshold. Although some experiments with cells have reported effects at field levels as low as 2 mG, there is no laboratory evidence for adverse human health effects at this level.

The Swedish study suggested a dose/response relationship for EMF exposure: The higher the estimated magnetic field exposure, the higher the cancer risk. To deduce from the Swedish study, however, that 2 mG is some sort of safety threshold is to read far too much into the data. The Swedish government has so far concluded that current knowledge does not provide sufficient basis for setting exposure limits .

*This estimate is based on the EPRI study of 992 homes, described on p. 49. An average magnetic field measurement was calculated for each home, based on measurements conducted in each room. The average of the 992 individual "home averages" was 09 mG.