Electricity, power lines, magnetic fields and childhood leukaemia
Magnetic fields: a ‘possible carcinogen’
In 2002, the International Agency for Research on Cancer (IARC) classified magnetic fields (also known as EMFs) of the type associated with our electricity supply as a class 2b carcinogen – possibly carcinogenic to humans.
In 2002, the International Agency for Research on Cancer (IARC) classified magnetic fields (also known as EMFs) of the type associated with our electricity supply as a class 2b carcinogen – “possibly carcinogenic to humans”. This was based on pooled epidemiological studies that reported an approximate doubling of leukaemia risk for children exposed at average levels above 0.3 - 0.4 microtesla. The UK average in homes is well below this, at about 0.05 microtesla.
In 2007, the World Health Organisation (WHO) estimated that, if the risk is real, up to 2,400 (5%) of worldwide childhood leukaemia cases per year could be attributable to magnetic field exposure above 0.3 microtesla.
Recent studies have also found increased childhood leukaemia risk with exposure to EMFs below 0.4 microtesla, in particular a 30 per cent increase with average exposures above 0.2 microtesla.
About 2% of UK homes have average levels above 0.2 microtesla. Under high voltage power lines values can be several or even tens of microtesla. EMF exposure can also be significantly above 0.2 microtesla from appliances in the home (including electric storage radiators), wiring faults and electricity cables under the street.
Other types of studies have advanced our understanding of how magnetic fields may cause the increased risk of leukaemia.
Birds and other animals use magnetic-field-sensitive biochemical reactions as navigation sensors. This has increased our understanding of the biological interactions of magnetic fields relevant to DNA damage, of the type that could lead to leukaemia.
The disruption by magnetic fields of our 24-hour circadian rhythm also lowers melatonin, an anti-cancer chemical, in our bodies. This is a pathway that may increase leukaemia risk, especially as melatonin is passed on to a developing foetus by the mother.
EMFs have now been shown to engender genomic instability, an evolving hallmark of cancer and in line with findings for established carcinogens.
Our 2005 report: Do electric and magnetic fields cause childhood leukaemia?
Our 2014 think tank report: Magnetic fields and childhood leukaemia – candidate mechanistic pathways
Raising awareness of the potential risk
Since 2004, Children with Cancer UK have been involved in a campaign to raise awareness of the potential role of EMF exposure in the causation of childhood leukaemia.
Part of the debate is around high-voltage overhead powerlines.
Underground powerlines tend to have lower levels of magnetic fields at ground level which are confined much closer to the line compared with overhead lines. They also do not cause high electric fields or corona ion emissions which can increase the toxicity of airborne toxic particles.
Children with Cancer UK was one of three management partners in the UK Government’s Stakeholder Advisory Group for Extremely Low Frequency Electric and Magnetic Fields (SAGE).
More than 40 partners worked together over the course of five years, from 2004. They produced two well-debated Official Reports for Government on various aspects of the health risks from magnetic fields and power lines. The Group particularly considered the options for alleviating public exposure.
SAGE 1: First interim assessment 2007
SAGE 1: Supporting documents 2007
SAGE 2: Second interim assessment 2010
In addition to childhood leukaemia, a number of other adverse health outcomes are also associated with magnetic field exposure. These include leukaemia and brain tumours in adults, miscarriage, heart disease and Alzheimer’s disease. Taking account of all of these health outcomes, SAGE concluded that in terms of cost-benefit it would be advantageous to place any new high voltage power lines underground.
Government formally responded only to the SAGE First Interim Report, which restricted the health considerations to childhood leukaemia.
SAGE 1: Government response to First interim assessment 2009
At present National Grid does try to avoid erecting power lines within 100 metres of existing houses. A much greater problem, which still remains, is the converse situation – the building of new houses near existing overhead powerlines.
World Health Organization, 2007, Extremely Low Frequency Fields. Environmental Health Criteria 238.
- Stakeholder Advisory Group on ELF EMFs (SAGE) precautionary approaches to ELF EMFs. First Interim Assessment: Power Lines and Property, Wiring in Homes, and Electrical Equipment in Homes. Date of issue: 27/04/2007 SAGE 1 First interim assessment 2007
- Stakeholder Advisory Group on ELF EMFs (SAGE) Precautionary approaches to ELF EMFs. Supporting Papers to the First Interim Assessment: Power Lines & Property, Wiring in Homes and Electrical Equipment in Homes. Date of issue: 27/04/2007 SAGE 1 Supporting papers 2007
- Government response to the Stakeholder Advisory Group on extremely low frequency electric and magnetic fields (ELF EMFs) (SAGE) recommendations. Date of publication: 16/10/2009 SAGE 1 Government response 2009
- Stakeholder Advisory Group on ELF EMFs (SAGE) Second Interim Assessment 2009 – 2010 Electricity Distribution (including low-voltage and intermediate-voltage circuits and substations) and Report on Discussions on Science. Date of issue: 08/06/2010 SAGE 2 Second interim report 2010