Documents of the NRPB: Volume 15, No. 2
AF McKinlay, SG Allen, R Cox, PJ Dimbylow, SM Mann, CR Muirhead, RD Saunders, ZJ Sienkiewicz, JW Stather and PR Wainwright
Advice on Limiting Exposure to Electromagnetic Fields (0-300 GHz)
This report reflects the understanding and evaluation of the current scientific evidence as presented and referenced in the full report.
The Board of NRPB has recommended the adoption in the UK of the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) for limiting exposures to electromagnetic fields (EMFs) between 0 and 300 GHz. This follows a thorough review of current scientific knowledge on the effects of EMFs and an extensive consultation exercise. The Board recognises the need to adopt a cautious approach in the interpretation of scientific knowledge and the benefits of common international guidelines.
- Following a review of the relevant scientific data (NRPB, 2004a) and an extensive consultation exercise, NRPB has issued new advice on exposure guidelines for electromagnetic fields (EMFs) (NRPB, 2004b). In establishing quantitative restrictions on exposure to EMFs a range of values are possible, particularly when taking into account uncertainties in the responses of different groups of individuals in the general population. The review of current scientific knowledge by NRPB staff, the adoption of a cautious approach to the interpretation of these data, and a recognition of the benefits of international harmonisation, combine in the Board's recommendation to adopt the ICNIRP exposure guidelines for occupational and public exposure to EMFs between 0 and 300 GHz (ICNIRP, 1998).
- The detailed scientific analysis by NRPB staff supports the recommendation by ICNIRP that exposure guidelines for members of the public should be more restrictive than for workers. This allows for a greater sensitivity to adverse health effects in the general population than for the working population. Increases in sensitivity may occur in infants and children, individuals being treated with medication, and those in the later years of life. The ICNIRP recommendation of a reduction factor of five in the basic restrictions for members of the public compared with workers is appropriate.
- In the light of ongoing research, major health risk assessments being carried out by the World Health Organization (WHO), and the possibility of further advice from ICNIRP, the Board considers that guidelines on limiting exposure to EMFs should be kept under review. NRPB staff will continue to monitor the results of research related to the effects of EMFs on health and to make further recommendations when appropriate.
- The Board recognises that there are concerns that prolonged low level exposure to EMFs across the range 0-300 GHz may be implicated in the development of long-term health effects, in particular cancer. Relevant epidemiological and biological studies have been reviewed in reports by the independent Advisory Group on Non-ionising Radiation (AGNIR, 2001a,b, 2003). These conclude that there is no firm evidence of such adverse health effects at the levels of EMFs to which people are normally exposed.
- An association between prolonged exposure to intense power frequency magnetic fields and a small raised risk of childhood leukaemia has, however, been found, the scientific reasons for which are presently uncertain. In the light of these findings and the requirement for additional research, the need for further precautionary measures should be considered by government.
- The National Radiological Protection Board (NRPB) has the responsibility for providing advice on limiting exposure of people to electromagnetic fields (EMFs). These include static, power frequency (50 Hz in the UK), and other extremely low frequency (ELF) electric and magnetic fields, and radiofrequency (RF) fields and radiation. The new advice from NRPB (2004b), supported by a review of the scientific evidence (NRPB, 2004a), updates previous advice on limiting exposure to EMFs (NRPB, 1993, 1999).
- These revised recommendations have been developed as part of the ongoing review by NRPB of the scientific evidence underlying the exposure guidelines for EMFs. The present review was requested by the Department of Health and has particularly examined the issues of uncertainty in the science and aspects of precaution. The advice on exposure guidelines is based on an assessment of the possible effects of EMFs on human health. It is derived from epidemiological studies of exposed human populations, experimental investigations, results from volunteer studies, and dosimetric information.
- In developing these recommendations, NRPB has drawn upon advice from individual UK and international scientific experts and from published comprehensive reviews by expert groups. It has additionally sought advice from an ad hoc expert group on weak electric field effects in the body. NRPB organised an open meeting to listen to public concerns about power lines in December 2002 and it was also aware of issues raised at open meetings organised by the Independent Expert Group on Mobile Phones (IEGMP, 2000). A consultation document on the new guidelines was issued in May 2003. Comments received from that consultation have been addressed in completing a review of the science and in formulating the advice.
- Generally, occupational exposure concerns healthy adults working under controlled conditions. These conditions include the opportunity to apply engineering and administrative measures and, where necessary and practical, to provide personal protection. For members of the public, similar controls do not generally exist, and individuals of varying ages can have wider variability in health status and responses to exposures to EMFs. For these reasons exposure restrictions for the public are lower than those recommended for the working population.
- Restrictions on exposure to EMFs are designed to prevent adverse health effects and are based on their interactions with body tissues. They are termed basic restrictions as they are developed from experimental data relating to thresholds for direct and indirect health effects, which give rise to the fundamental limits on exposure. Generally, the basic restrictions are not readily measurable.
- Direct effects are those resulting from the interaction of EMFs with the human body. For exposure to static magnetic fields, the restrictions are intended to avoid the induction of vertigo and nausea. For electric and magnetic fields, above frequencies of about 100 kHz, which include microwaves, the restrictions are intended to prevent adverse effects due to excessive whole- and partial-body heating.
- Indirect effects are those resulting from an interaction between EMFs, an external object such as a vehicle or other mechanical structure, and the human body. For these effects, advice on limiting exposure is provided to avoid the shocks and burns that might result. Such effects may be avoided by limiting the external electric field or by other engineering or administrative controls.
- Reference levels are also given; these are conservatively derived levels relating to the electric field, magnetic field, or current for comparison with measurements that can readily be made. Comparison of measurements with the reference levels can be used to assess whether compliance with the basic restrictions has been achieved. If the field to which a person is exposed exceeds the relevant reference level it does not necessarily follow that the basic restriction is exceeded. It is, however, then necessary to investigate compliance with the basic restriction using more detailed methods of exposure assessment. The reference levels may be used to indicate whether there is a need to take appropriate action to prevent shock and burn.
The National Radiological Protection Board (NRPB) has the responsibility for providing advice on exposure guidelines for electromagnetic fields (EMFs). As part of its policy of ongoing evaluation of scientific evidence and health risk assessment, NRPB has reviewed its advice on limiting exposure to EMFs and, at the request of the Department of Health, has particularly addressed the issues of uncertainty in the science and aspects of precaution.
As a result of this review, NRPB recommends the adoption of the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) for limiting exposure to EMFs.
In its review of the science, NRPB has drawn upon advice from individual UK and international scientific experts and from published comprehensive reviews by expert groups. It sought advice from an ad hoc expert group on weak electric field effects in the body and gave careful consideration to the views expressed in response to a consultation document on its proposed guidelines issued in May 2003. NRPB has listened to the concerns raised at a public open meeting on power lines held in December 2002 and is also aware of issues raised at the open meetings held around the country by the Independent Expert Group on Mobile Phones (IEGMP).
Uncertainties, particularly in relation to the responses of different groups of individuals, result in a range of possible values for restrictions on exposure. The review of the science, the need to adopt a cautious approach, and recognition of the benefits of international harmonisation combine in the recommendation to adopt the ICNIRP EMF exposure guidelines. These guidelines incorporate two tiers of protection: one set of values for occupational exposure and another, more restrictive, set for general public exposure.
NRPB is committed to monitoring the results of further research related to effects of EMFs on health and to revising its advice when appropriate.
There remain concerns about possible effects of exposure to EMFs and, in particular, power frequency magnetic fields. The view of NRPB is that government should consider the possible need for further precautionary measures.
Last reviewed: 6 August 2013