Because we use electric power throughout our homes and workplaces, we are all subject to electric and magnetic fields (EMF) that are created by the voltages and currents present in electrical conductors and electrical equipment. Interest in the health effects of electric-power EMF has been motivated by several epidemiologic studies showing weak associations between surrogate measures of low-level EMF exposure and both childhood cancers and adult cancers. Due to the ubiquitous presence of electric power, the public health implications of this association are potentially very significant; however, good evidence for a causal relationship between exposure to EMF and any health effect has not been found. Yet, uncertainty, plus the suggestive epidemiologic findings, have fueled public anxiety and media attention. To put this potential health threat into perspective, it is important to consider the strength of the epidemiology, the availability of supporting animal studies, and mechanistic or biophysical information about the interaction of EMF with matter. Any discussion of steps that might be taken to avoid potential EMF health-effects needs to incorporate a perspective on how hypothetical EMF risks relate to other hazards to life and health.