Until 2004, the NRPB published its own exposure guidelines. In March 2004, it recommended instead that the UK should adopt the ICNIRP 1998 guidelines. It actually published two documents:
Advice on Limiting Exposure to Electromagnetic Fields (0-300 GHz)
Review of the Scientific Evidence for Limiting Exposure to Electromagnetic Fields (0-300 GHz)
In July 2004 the NRPB also published a Summary of comments received on the May 2003 Consultation Document and responses from NRPB
see also more on other NRPB statements on EMFs
What they said
“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 restriction for members of the public compared with workers is appropriate.”
|1993 NRPB Guidelines|
(the same for occupational and public)
1998 ICNIRP Guidelines
|Basic Restriction(the quantity which must not be exceeded)||Induced current density in the central nervous system||10 mA m-2||10 mA m-2||2 mA m-2|
|Reference Level(not a limit in itself but a guide to when you need to investigate the basic restriction)||Magnetic field||1600 µT||500 µT||100 µT|
|Electric field||12 kV m-1||10 kV m-1||5 kV m-1|
These values are for 50 Hz - see here for the values at 60 Hz
The actual field values required to exceed the basic restriction are higher than the reference levels and are obtained by numerical calculation. For public exposure (and for uniform fields such as found from power lines) the conclusion is:
Basic restriction: 2 mA m-2 in the central nervous system
ICNIRP reference level: 100 µT
ICNIRP reference level: 5 kV m-1
These values are for 50 Hz - see here for the values at 60 Hz
* The Dimbylow calculations give a value of 9.2 kV m-1. HPA suggest 9 kV m-1 which includes a further small margin.
Effects considered in providing advice
Both the NRPB and ICNIRP levels are chosen to prevent fairly well-established effects of EMFs on the body (at power frequencies, the effect on induced currents on the central nervous system). NRPB state:
“It is concluded that there are scientific data indicating the need for appropriate values for restrictions on exposure. These data derive from experimental studies related to effects of EMFs on the central nervous system… The restrictions on exposure and recommendations for further investigation, where relevant, are derived from data on these effects.”
But in arriving at these recommendations, NRPB also reviews the evidence for the whole range of other possible effects of EMFs. It concludes:
“Evidence of other possible effects associated with EMF exposure derives principally from epidemiological studies and from some experimental studies. The main, but not sole, subject of such studies has been cancer. These studies have been reviewed extensively by expert groups, including AGNIR, and are summarised in the associated review of the science (NRPB, 2004). It is concluded that currently the results of these studies on EMFs, taken individually or as collectively reviewed by expert groups, are insufficient either to make a conclusive judgement on causality or to quantify appropriate exposure restrictions.”
NRPB recommendations on precaution
However, although NRPB concludes these studies do not justify quantitative exposure limits, it does suggest they may justify considering precautionary approaches.
The summary Statement says:
“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 main body of the document states:
“There remain concerns about the possible effects of exposure of children to power frequency magnetic fields. The view of NRPB is that it is important to consider the possible need for further precautionary measures in respect of exposure to children to power frequency magnetic fields.”
“The government should consider the need for further precautionary measures in respect of exposure of people to EMFs. In doing so, it should note that the overall evidence for adverse effects of EMFs on health at levels of exposure normally experienced by the general public is weak. The least weak evidence is for the exposure of children to power frequency magnetic fields and childhood leukaemia.”
more on precaution generally.
The legal position
The NRPB’s role is to provide advice to Government. Its advice does not have direct force on either industry or the public.
In August 2004, in response to the NRPB’s recommendation, the Parliamentary Under Secretary for Public Health (Melanie Johnson) wrote to the Chairman of the NRPB welcoming the new advice. The letter included a 10 point annex describing the way Government intends to implement the NRPB advice. It points to the need for inter-departmental working and introduces the initial plans for a wider stakeholder process in order to consider the possible need for further precautionary measures in respect of extremely low frequency (ELF) electromagnetic fields (EMF).
The key statement about implementation is:
“… the Government expects the NRPB guidelines to be implemented in line with the terms of the EU Recommendation, that is, taking account of the risks and benefits of action. Preliminary discussions have already taken place to identify what reasonable actions might be taken.”
On precautionary measures, it says:
“The Government will be exploring further the practical applications of precautionary measures within a stakeholder engagement process. This will be the subject of wide consultation and will explore any risks and benefits arising in the same manner as a Regulatory Impact Assessment.”