6 March 2001
nrDoc. NRPB, 12, No. 1 (2001)
The Board of NRPB welcomes the report by its Advisory Group on Non-ionising Radiation (AGNIR) on extremely low frequency (ELF) electromagnetic fields (EMFs) and the risk of cancer 1. This is a substantive report that has examined comprehensively relevant experimental and epidemiological studies on possible risks. It complements and updates previous reports on this topic by AGNIR 2- 4.
The Board notes the conclusions of the report. In particular, that the question of whether exposure to electromagnetic fields can influence the development of cancer cannot at present be completely resolved. This is despite the results from extensive epidemiological studies carried out in recent years with greatly improved methodology. Included in these are the findings of the UK Childhood Cancer Study (UKCCS) which is the world's largest case control study on the causes of childhood cancer.
The annual birth rate in the UK is about 700,000. There are around 500 cases of leukaemia and about 1000 cases of other cancers reported in children (under 15 years) in the UK each year. The report by AGNIR concludes that any risk relates to leukaemia in children and young persons and in particular to those exposed at relatively high levels of average domestic exposure to magnetic fields at or above 0.4 microtesla (µT) (400 nanotesla (nT)). For the UK population this relates to about 0.5% of the total population.
In the absence of any special effect of magnetic fields 2 of the 500 cases of childhood leukaemia a year would be associated with exposures of 0.4 µT or more; if there were an effect of magnetic fields a further 2 cases might be produced, 1 case every 2 years being possibly due to proximity to power lines. This would imply an increase in the annual risk of leukaemia in childhood from about 1 in 20,000 to 1 in 10,000 and would correspond to an increase in the overall risk of leukaemia to age 15 years from 1 in 1400 to 1 in 700 for the 0.5% of children who were highly exposed. As has already been demonstrated in the UKCCS it has not been possible to detect this increase in the UK. At this low level of risk some of the increase may be due to biases in the way the data have been collected. There is no evidence that residential exposure to EMF is involved in the development of cancer in adults, and in particular of leukaemia or brain cancer.
The review of experimental studies by AGNIR gives no clear support for a causal relationship between exposure to ELF EMF and cancer.
Despite the small proportion of children in the UK likely to be exposed at levels above 0.4 µT the Board's view is that there is a need to understand better the factors in the UK that might result in such levels of residential exposure to magnetic fields. It is already known from the results of the UKCCS that this is not attributed solely to proximity to power lines. International work in this area may help to explain the observed association between high levels of exposure and an increase in the leukaemia risk in children. Further information is also needed on any factors that may result in bias or confounding in the published residential studies. Any new experimental studies should be based upon carefully designed, hypothesis driven investigations, as recommended by AGNIR. The UKCCS is examining other factors that may be implicated in the development of childhood leukaemia.
The AGNIR report indicates that, in adults who are occupationally exposed, a causal relationships between EMF exposure and tumour incidence at any site is not established. There does, however, remain the possibility that further data on any effects on health of exposure to EMF could be obtained from epidemiological studies on occupational groups as their exposures will tend to be higher than those in residential studies. Occupational average exposures of some individuals in some industries may be up to a few tens of microtesla. The Board considers that such studies should be supported by Government and other funding bodies.
The Board supports the recommendation by AGNIR that further residential epidemiology studies in the UK of childhood leukaemia would be unable to provide any better information. The low levels of exposure generally in the UK do not provide a population that is large enough to detect any effect on leukaemia incidence at average exposures at or above 0.4 µT. More informative results may come from residential studies in other countries where exposures may be higher as a consequence of differences in the electricity supply and distribution systems.
Guidelines for limiting exposure to electromagnetic fields are presently based on preventing established health effects, which for ELF EMF are those related to induced currents in the tissues of the central nervous system. Epidemiological studies are also taken into account. The Board considers that the AGNIR report provides no additional scientific evidence to require a change in exposure guidelines.
1 ELF Electromagnetic fields and the risk of cancer. Report of an Advisory Group on Non-Ionising Radiation. Doc. NRPB, 12, No. 1, 1-179 (2001).
2 Electromagnetic fields and the risk of cancer. Report of an Advisory Group on Non-Ionising Radiation. Doc. NRPB, 3, No. 1, 1-138 (1992).
3 Electromagnetic fields and the risk of cancer. Supplementary report by the Advisory Group on Non-Ionising Radiation (May 1993). Radiol. Prot. Bull., 142 (1993).
4 Electromagnetic fields and the risk of cancer. Supplementary report by the Advisory Group on Non-Ionising Radiation (12 April 1994). Doc. NRPB, 5 No. 2, 77-81 (1994).
6 March 2001
Last reviewed: 4 December 2012