"SAGE" stands for Stakeholder Advisory Group on ELF EMFs and describes precautionary approaches to ELF EMFs. It is a standard that is being used mainly for 50/60Hz AC magnetic flux density in general areas of a residential homes. It does not differentiate between day and night exposure. The study was mainly focusing on a relationship between extremely low frequency EMF and childhood leukemia.
The SAGE process was initiated by National Grid but is was later under the lead of the Department of Health. It was funded equally by the Department of Health, the Electricity Industry (National Grid and the Energy Networks Association) and the charity CHILDREN with LEUKAEMIA.
Government officials are a part of the process, informing the debate and supplying factual input to the Assessment. The Government supports the production of the Assessment and welcomes the material and the contribution it makes to consideration of the EMF issue. However, this does not necessarily imply that Government is aligned with the views expressed or the conclusions stated in this Assessment and Government representatives will not be formally supporting any particular conclusions and options outlined in the Assessment, as that is a matter for Government as a whole to consider once it has received the Assessment.
The SAGE recommendation is solely focused on low and extremely low frequency EMF. This is produced by the flow of AC alternating electrical current, typically by home appliances, power lines, substations and house main lines. The association between magnetic fields and an increased risk of childhood leukaemia is often expressed as occurring at long-term average fields greater than 0.4 µT. For magnetic fields, therefore, they recognise that, within the overall concept of “as low as reasonably achievable”, there is a greater imperative to reduce fields that are above 0.4 µT, and a lesser imperative to reduce fields that are below 0.4 µT, and what is “reasonable” will be different in these situations. They also recognise that 0.4 µT is not a precise threshold, does not represent a boundary between “safe” and “unsafe”, and should not be used as such. It is simply not possible to be dogmatic about where and at what rate the risk, if any, increases.
The epidemiological evidence on childhood leukaemia, as summarised by the Ahlbom pooled analysis, suggests a relative risk of two (potentially doubling for children in homes where the field over the general area of the house, averaged over 24 hours or longer, fell in the category “greater than 0.4 µT”, when compared to a reference category of “less than 0.1 µT”.