Basic restrictions in EMF exposure guidelines.

Different bodies have set guidelines restricting exposure to electric and magnetic fields. The limits at power frequencies recommended by these guidelines and the scientific basis and rationale for setting them have been reviewed, starting with the WHO Environmental Health Criteria 69 on Magnetic Fields, published in 1987. These guidelines are all designed to limit the induced current density to 10 mA m(-2), sometimes reduced by an additional safety factor of five for the general public. While published guidelines have, to date, universally adopted a restriction based upon induced current density, the internal electric field is the more fundamental quantity in determining biological effects. It is recommended that consideration be given to using the internal electric field rather than current density in future guidelines. Those who are responsible for setting guidelines need good scientific information on which to be able to set their limits. While there is already a significant weight of scientific evidence upon which exposure restrictions can be based, there is a need for more research to reduce uncertainties and to enable greater precision in the setting of limits. Some suggestions for future research directions, particularly aimed at further understanding of the interaction of electric fields with the nervous system, are suggested in this paper and are developed more widely in the following papers covering the proceedings of the EPRI Guidelines Science Workshop held in Brussels in June 2000.