However, the possible effects of radiation or extreme low frequency fields from VDTs on pregnancies continue to concern employees. ELF fields are considered as separate, independent, non-radiating electric and magnetic fields. Electric fields are produced by voltage and increase in strength as the voltage increases. Magnetic fields are from the flow of current through wires or electrical devices and increase in strength as the current increases. Electrical equipment usually has to be turned on for a magnetic field to be produced.
Electric fields are present even when equipment is turned off, as long as it is plugged in.
Current research has focused on potential health effects of magnetic fields. This is because some inconclusive epidemiological studies have suggested increased cancer risk associated with estimates of magnetic field exposure. No similar associations have been reported for electric fields. Exposure to EMFs depends on the strength of the magnetic field sources, the distance from those sources, and the time spent in the magnetic field. Potential health effects were first noted in the early 1970s in scientific and medical literature.