07/02/2014 - Power lines still associated with childhood leukaemia
The British Journal of Cancer and the Childhood Cancer Research Group issued a very misleading Press Release entitled: 'OVERHEAD POWERLINES DON'T RAISE LEUKAEMIA RISK IN CHILDREN'
Their important new paper by Bunch, et al , does not show this. The authors have analysed a great deal of data for all high-voltage powerlines of 132,000 volts (132 kV) and above.
The BJC/CCRG Press Release headline and the dismissive comments by the lead author and by Cancer Research UK's head of health information that claim the study indicate that overhead powerlines don't cause leukaemia or other cancers in children are very dishonest. The supplementary data tables (not in the actual paper) do show a fairly consistent relative risk of about 1.5-fold up to 199 metres over 4 decades 1962-1999 for 132 kV powerlines - the type generally close to residential housing.
The main association of electrical power and incidence of child leukaemia (CL) has been the magnetic fields (EMFs) from all sources that are associated with our use of electricity. A recent large meta-analysis by Zhao, et al,  has confirmed an approximate doubling at 0.4 microteslas, as does the new EC SCENIHR draft report . This magnetic field association close to powerlines (and other equipment) is, in no way, challenged by this new study.
An earlier paper by the same research centre (CCRG) by Draper, et al , showed an association of childhood leukaemia CL with proximity to 275 kV and 400 kV lines. The CCRG later reported that the EMFs had fallen off within 100 metres from the powerlines to levels below those produced by other electrical causes (including underground cables running under our pavements and house wiring) .
Further than about 100 metres from powerlines, any effect on cancer incidence is much more likely to be due to toxic aerosols (from pollution) being charged up by the corona discharges from the high voltage powerline. When this happens, and they are breathed in, they have about a 10-fold increased risk of sticking to the lung surface and being absorbed into the bloodstream. This was repeatedly reported in papers by Professor Denis Henshaw and his Human Radiation Effects team at the University of Bristol over the period 1995-2010.
In this new study the CCRG researchers added more cases and a large number of lower-powered 132 kV powerlines (which often pass over or very close to homes), when according to Dr John Swanson (a senior National Grid scientist and co-author of this new study) EMFs typically fall off to background levels from other sources (less than 0.05 microteslas) within 50 metres of the powerline. Dr Swanson runs an excellent website EMFs.info with a mass of good details about ELF EMF exposure levels from our uses of electricity and we do not suspect him of making or supporting the contested claims in the BJC/CCRG Press Release.
As there is little evidence that the risk of childhood leukaemia is increased at magnetic field (EMF) levels below 0.2 microteslas, it is vital to analyse cases and controls living within 0-49 metres in order to test whether proximity to overhead HV powerlines increase the risk . The first analysis band in the published paper is 0-199 metres and is of little use to determine if living close to an overhead high voltage powerline can increase the risk of childhood leukaemia, as well over 75% of the children will be exposed to higher EMFs from other sources which will greatly reduce any effect of magnetic fields from the powerlines.
Another recent important study on powerlines and childhood leukaemia by a team at INSERM published in the BJC last year found an increased risk within 50 metres of a high-voltage overhead line, but not further away . This is briefly mentioned in the new paper, but the very important implications of the 50 metre distance limit finding are not discussed.
The New BJC paper is an important contribution to the high-voltage powerline and increased incidence of childhood leukaemia debate and we will soon be issuing a full news story with an analysis about what their interesting results might indicate.
Most of the cases analysed ion this paper will be living in higher EMFs produced by other sources, which will reduce the apparent effect of the fields from the powerlines
Professor Mike O'Carroll has produced a helpful summary and criticism of the flawed BBC reporting of this new study. See: Revolt NL376 (24 KB pdf file)
A more detailed report about this will be posted on Powerwatch next week (10-14th February).
- Bunch, K.J. et al (2014) Residential distance at birth from overhead high-voltage powerlines: childhood cancer risk in Britain 1962-2008 British Journal of Cancer
- Zhao et al. (2013) Magnetic fields exposure and childhood leukaemia risk: A meta-analysis based on 11,699 cases and 13,194 controls. Leukaemia Research (In press)
- See: SCENIHR
- Draper G, Vincent T, Kroll ME, Swanson J (2005) Childhood cancer in relation to distance from high voltage power lines in England and Wales: a case-control study. BMJ 330(7503): 1290-1294.
- Kroll ME, Swanson J, Vincent TJ, Draper GJ (2010) Childhood cancer and magnetic fields from high-voltage power lines in England and Wales: a case-control study. Br J Cancer 103(7): 1122-1127.
- Philips A, et al, (2013) Adult cancers near high-voltage power lines - commentary, Epidemiology 2013 Sep;24(5):782-3
- Sermage-Faure C, et al, 2013, Childhood leukaemia close to high-voltage power lines - the Geocap study, 2002-2007. Br J Cancer 108(9): 1899-1906
News story issued 7-Feb-2014 and edited with minor revisions on 8-Feb-2014.
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