In April 2007, news stories about the potential health risks caused by exposure to electromagnetic fields (EMF) circulated once again in the UK. These stories were triggered by two events: first, the publication of a report by the Stakeholder Advisory Group on Extremely Low Frequency Electromagnetic Radiation (SAGE) and, second, a call from Lawrie Challis, chairman of the Mobile Telecommunications and Health Research programme, discouraging children from placing wireless-enabled portable computers on their laps because of the risk of EMF exposure to the lower torso. These events highlight the increasing use of EMF-emitting technologies, and the need for clear strategies that confidently identify and prevent any health risks that might arise from the growing reliance on this technology.
SAGE was commissioned by the UK Government and was asked to consider precautionary measures for two sources of EMF where health risks are uncertain: high-voltage overhead power lines; and domestic wiring, equipment, and appliances. With regards to power lines, the group identified several options that ranged from doing nothing to a more draconian alternative that included compulsory eviction from, or demolition of, properties up to 600 m from power lines. The option SAGE presented to the UK Government as “best available” was the need to prevent new power lines and new residential buildings (and some non-residential buildings, such as schools) from being built within 60 m of each other. Inevitably, this option represented a compromise between the two extremes and, crucially, did not address existing situations where power lines and residential buildings already coexist.
SAGE's remit, although worthy, was fundamentally flawed because the health effects of exposure to EMF remain largely unknown. Evidence of causation is clearly needed before any government can make a decision on appropriate preventative measures, otherwise, whether the intervention is the right one is difficult to assess. The question of disease causation and exposure to EMF has been addressed in a wealth of studies, but considerable uncertainty exists. Epidemiological studies show significant associations between high background magnetic fields located in homes and an increased risk of childhood leukaemia, but this association might not represent causation. As a result, the International Agency for Research on Cancer (IARC; Lyon, France), has classified power-frequency EMF as “possibly carcinogenic” for childhood leukaemia. Similarly, the California Department of Health Services in the USA has also noted that such a link with regards to adult leukaemia, adult brain tumours, and childhood leukaemia is also possibly carcinogenic, but not definitively so. For other cancers, more debate exists: indeed, IARC has classified the evidence linking EMF with all types of human cancer, other than childhood leukaemia, as “inadequate”.
With rapid advances in modern technology, continuing uncertainty about the health risks is no longer an option. Robust studies are needed urgently to bring reasoned clarity to all decision-making. Previous studies have been beset with weaknesses, such as inadequate adjustment for confounders, difficulties in replicating findings, and problems in measuring exposure (ie, recall bias and absence of standardised measurements). Large prospective multicentre studies are, therefore, needed to increase statistical power, and standardised methods for measuring exposure (such as personal field meters) need to be used over long periods of time. Measures of EMF exposures in different population groups (eg, children, the elderly, different ethnic groups, or people on medication) are also needed, as are anatomical site-specific assessments. Such studies need to be done independently from industries connected with the technologies under scrutiny so that data interpretation is not compromised by vested interests; an eventuality typified by recent allegations in the UK about the deliberate concealment of a risk-assessment report commissioned by a mobile telephone company.
Until we have the necessary evidence to fully assess safety, a precautionary approach is, of course, prudent. But, specific interventional measures should not be taken without a suitable evidence-base of causation, and knee-jerk reactions that potentially hinder innovation are not helpful. However, with increasing modernisation of societies across the world, and with cancer becoming the number one cause of mortality in many developed, and developing, countries, embracing new technology should be done in parallel with robust assessments of any associated dangers.
http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(07)70149-3/fulltext
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