Is there something significant about the 2-mG magnetic field level?
A typical U.S. home has a background magnetic field level (away from any appliances and averaged over time) that ranges from 0.5 mG to 4 mG, with an average value of 0.6 mG. This estimate is based on the Electric Power Research Institute study (see related discussion at beginning of this chapter; Zaffanella et al., 1993). Most ordinary electrical equipment produces higher magnetic fields close to the source. (for examples of fields from various EMF sources are given later in this chapter.) Following standard epidemiologic practices, several EMF human health studies have used average exposures of 2 or 3 mG as an arbitrary cutoff point to define broad categories of exposure. Below this level, subjects were considered “unexposed,” and above this level, they were considered “exposed.” In some studies, a higher cancer risk was found within the exposed group. Two milligauss was significant in one influential Swedish study in that it was used as the boundary to define the exposed group, not b
