02/11/2000 - NRPB response to UKCCS plus Powerwatch comments relating to increased child leukaemia (quite scientific)
Further developments have taken place following the 14th November 2001 NRPB statement, which we believe was seriously flawed. Mrs Maureen Asbury is a member of the Trentham Environmental Action Campaign, a group of people living in fields of several microtesla directly under a 132 kV power line. Dr John Stather (NRPB) wrote a very misleading letter to Mrs Asbury. She complained to the Chairman of the NRPB (Sir Walter Bodmer), copying it to Govt.Ministers. She has now had a reply from Dr Stather's boss, the NRPB Director, Professor Roger Clarke.
The letter from Professor Clarke expressed regrets that Dr Stather's letter "did not contain the latest information". He said that the NRPB posted an additional information sheet to their web site on 28th November that discusses the new British Journal of Cancer meta-analysis. In this, the NRPB now admit that living in magnetic fields of 0.4 µT or more doubles the risk of leukaemia. (95% confidence interval 1.27-3.13) Adjustment for factors such as socio-economic status and type of dwelling did not change the results appreciably.
The NRPB try to minimise the implications of this result by adding a completely gratuitous and misleading fact "the leukaemia risk is small nationally (less than 1 in 20,000 per year)." The risk is small only due to the fact that few people live in such fields. For people like Mrs Asbury, who unwillingly live in EMF pollution of several microtesla, the implications of the BJC meta-analysis are enormous.
The NRPB have not withdrawn or modified the earlier flawed statement which we comment on below.
Professor Nic Day, the lead researcher for the UKCCS EMF analyses, has now been appointed to the Board of the NRPB and has also been awarded a CBE in the New Year Honours. We offer our congratulations. UK EMF research is increasingly looking incestuous.
We believe that the following NRPB Response Statement is scientifically and morally flawed
NRPB: The first results of the EMF part of the case-control UK Childhood Cancer Study (UKCCS) were published in 1999 . The main conclusion of the analysis was that there was no evidence that exposure to magnetic fields associated with the electricity supply in the UK augments risk for childhood leukaemia, cancers of the central nervous system, or any other childhood cancer.
NRPB: Recently an important subsidiary analysis has been carried out which focuses on the relationship between childhood cancer and living near to power lines . The results, published in the British Journal of Cancer, are consistent with those based on measurements in the first analysis. There was no evidence that either residential proximity to electrical installations, or the magnetic field levels they produce, is associated with increased risk of childhood leukaemia or any other cancer.
NRPB: The UKCCS was set up in the early 1990s at a time when previous studies had suggested an association between exposure to power frequency electromagnetic fields (EMF) and the development of childhood malignant disease, especially leukaemia and cancers of the central nervous system . The main analysis  was based on residential and school measurements of magnetic flux density.
NRPB: Exposure was estimated for the year preceding the date of diagnosis (or an equivalent date for controls) by weighting the measurements by the time spent in bed, at school and elsewhere, as determined during interview. Exposure estimates were adjusted for appliance and power line historical fields as necessary. The study found no association between measured power-frequency magnetic field exposure and risk for any malignancy .
NRPB: Several previous epidemiological studies have used distance from power lines as a crude marker of exposure . Some have shown associations with childhood cancer; others have not. A recent view put forward is that either distance is a more stable surrogate for historical magnetic field exposure or that it may be a proxy measure for some unknown 'causal exposure' factor, less closely related to average measured magnetic fields . During the course of the original study, details of external sources such as high voltage lines, underground cables, substations and some types of distribution circuits, were collected for the homes of most cases and one control per case. Home addresses and grid references were provided on questionnaires sent to electricity companies, masked with respect to case-control status. The details have provided study investigators with the opportunity to examine the postulated association between disease and distance. The effect of magnetic fields calculated from power lines alone has also been examined, using categories selected beforehand to be the same as those used for the measured analysis .
NRPB: The results are consistent with the previously reported results based on measured magnetic fields . The study found no evidence that proximity to electrical installations, or the magnetic field levels they produce, is associated with increased risk of childhood leukaemia or any other cancer .
NRPB: All homes with external source information were examined, giving 3380 cases and 3390 controls, as compared to the 2226 case-control pairs in the measurement based analysis . The proximity study included the great majority of eligible households (85% of interviewed cases) so the possible effect of participation bias was small. Restricting the analysis to those children who had lived in the same home for all the year of interest (approximately 90% of study subjects) made little difference to the results.
References (NRPB 1 to 4, plus additional Powerwatch Refs 5 to 9)
- UK Childhood Cancer Study Investigators. Exposure to power frequency magnetic fields and the risk of childhood cancer. The Lancet, 354, 1925-1931 (1999)
- UK Childhood Cancer Study Investigators. Childhood cancer and residential proximity to power lines. British Journal Cancer, 83, No. 11, 1573 -1580 (2000)
- UK Childhood Cancer Study Investigators. The UK Childhood Cancer Study: objectives, materials and methods. British Journal Cancer, 82, No. 5, 1073-1102 (2000)
- NAS-NRC. Possible health effects of exposure to residential electric and magnetic fields. National Academy Press, Washington DC (1997)
- Interaction of static and Extremely Low Frequency electric and magnetic fields with living systems: health effects and research needs, Repacholi MH and Greenebaum B, Bioelectromagnetics 1999, 20: 133-160
- Assessment of health effects from exposures to power-line frequency electric and magnetic fields, NIEHS Working Group Report: NIH Publication 98-3981. Research Triangle Park; NIEHS 1998
- Health Effects from Exposure to Power-Line Frequency Electric and Magnetic Fields, NIEHS/NIH Pub. 99-4493, prepared in response to the 1992 US Energy Policy Act (PL 102-486, Section 2118)
- A pooled analysis of magnetic fields and childhood leukaemia, Ahlbom, et al, British Journal of Cancer (2000) 83(5), 692-698.
- A pooled analysis of Magnetic Fields, Wire Codes, and Childhood Leukemia, Greenland, et al, Epidemiology, Vol.11 No.6, 624-634.