This book examines the health effects of exposure to static electric and magnetic fields found in selected industries, such as medical facilities with magnetic resonance imaging (MRI), high-energy physics research facilities and some transportation systems. To date, research on their health effects lags far behind the rapid advances in technology. Electric and magnetic fields are generated by natural phenomena such as the Earth s magnetic field, thunderstorms, and by man-made sources that use electricity. When such fields do not vary with time they are referred to as static. For static electric fields, studies carried out to date suggest that the main effect is discomfort from electric discharges to the body. For static magnetic fields, acute effects are only likely to occur when there is movement of a person in the field. For example, a person moving within a relatively high field can experience sensations of vertigo and nausea, and sometimes a metallic taste in the mouth and perceptions of light flashes. Although only temporary, such effects may have a safety impact for workers executing delicate procedures, e.g. surgeons performing operations within MRI units. Even when at rest, a person will experience internal body movement, such as blood flow or heart beat. When placed within a high magnetic field, electrical fields and currents are generated around the heart and major blood vessels that can impede the flow of blood. Possible effects range from minor changes in heartbeat to an increase in the risk of abnormal heart rhythms that might be life threatening."