David C Renew | PubMed Health

PubMed2002

Exposure guidelines for low-frequency electric and magnetic fields: report from the Brussels workshop.

The EMF Exposure Guidelines Science Workshop was held to evaluate the information base for guidelines for electric and magnetic field exposures at extremely low frequencies, to identify research needs, and to discuss how best to apply scientific knowledge in developing exposure recommendations. Although the existing guideline values are based on electrostimulation of nerve and muscle tissues, guidelines must also consider controversial studies of potential health effects from chronic exposures at environmental levels that are far too weak to cause electrostimulation. The size of the safety factor applied in specifying exposure limits reflects a variety of factors that introduce uncertainties. These include confidence in existing dose-effect relationships, population diversity, the reliability and precision of techniques to control over-exposure, and completeness of the information base, particularly regarding long-term effects. Specific research questions that can change the level of uncertainty meaningfully were identified in these areas: biophysical mechanisms of electrostimulation; the range of thresholds throughout exposed populations; cancer causation in children and adults, including a possible role for contact currents; cognitive, behavioral, and physiological effects on the central nervous system; improved dosimetry; and better understanding of electromagnetic interference with implanted biomedical devices such as pacemakers, defibrillators, and physiological monitors. This report introduces ten papers from the workshop that address these and related topics in detail.

Biophysical Phenomena↗

PubMed2002

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.

Electromagnetic Fields↗