The statement from the Electricity Association representing UK Power Companies, dated 6th October 2002, PR/24/2002,
concerning the California Health Department Report into possible risks from electric and magnetic fields associated with the electricity supply.


- Commentary by Professor Denis L Henshaw -


On Friday, 11th October 2002, the California Health Department (DHS) released a major report on the possible health effects of exposure to electric and magnetic fields, EMFs, associated with powerlines and the electricity supply generally. The Report, based on the assessment of three scientists, makes a number of statements:

To one degree or another all three of the DHS scientists are inclined to believe that EMFs can cause some degree of increased risk of childhood leukaemia, brain cancer, miscarriage and Lou Gehrig’s Disease (or Amyotrophic Lateral Sclerosis, ALS, a form of motor neurone disease).

All three scientists had judgements that were “close to the dividing line between believing and not believing” that EMFs cause some degree of increased risk of suicide.

For adult leukaemia, two of the scientists are “close to the dividing line between believing or not believing” and one was “prone to believe” that EMFs cause some degree of increased risk.


Part of the statement by the Electricity Association reads:

“In the last two years alone the evidence [concerning EMF and health] has been reviewed by the International Agency for Research on Cancer (IARC), the European Commission’s Scientific Committee and the UK’s National Radiological Protection Board (NRPB). The work by California Department of Health Services is another review of essentially the same evidence, but its conclusions are clearly out of line with the worldwide consensus and have been heavily criticised.”

Parts of this statement are incorrect while other parts are highly misleading. A possible relationship between miscarriage and EMFs was not considered by either the IARC or NRPB Reports, nor were these reports concerned with depression and suicide (see comparative summary in Table 21.2 of the California Report).

In fact, where the California, NRPB and IARC reports overlap there are clear areas of agreement. For example, all three reports acknowledge a doubling of childhood leukaemia risk associated with magnetic fields above 0.4 microtesla (mT) and for this reason magnetic fields have been classified as a possible carcinogen. A report by the NRPB in the Autumn of 2001 agrees with the conclusion of the California Report that there is an association between magnetic fields and the incidence of ALS.

There are two important reasons why the California Report differs from earlier reports. Firstly, the October 2002 California Report was able to draw on important scientific evidence published since the publication of the NRPB and IARC Reports in 2001. Secondly, the terms of reference of the California Report are different to that of the earlier reports in that it is concerned with the degree of confidence in the scientific evidence, specifically whether it is more likely than not that exposure to magnetic fields is associated with an increased risk of a given health condition.

It is interesting to note that the criticisms of the California Report have largely originated from power companies or individuals funded by power companies. Independent scientists have largely welcomed and congratulated the authors on the report.

The Electricity Association statement includes the following quotation from Dr John Swanson:

“.....exaggerated claims that are not supported by the evidence do not help. After 20 years and £300m of research, scientists across the world are increasingly coming to the view that there is no major public health risk from exposure to EMFs.”

The findings of the California Report have taken account of important new research published in the last 18 months. The conclusion that magnetic field exposures lead to an increased risk of miscarriage is based on a number of studies including two large studies published in January 2002 involving women exposed in their homes. There are also a number of ways in which magnetic fields interact with the human body. For example, there are now a number of studies in human populations reporting that magnetic field exposures as low as 0.2 mT, well below that seen near high voltage powerlines, suppresses the nocturnal production in the pineal gland of the hormone melatonin. Melatonin is a natural anti-cancer agent and reduced levels in the body are associated with depression. Melatonin readily crosses the placenta and it is highly effective at preventing oxidative damage to the fetus. Overall, there is at least one plausible mechanism to explain the conclusion now reached by the California Report that magnetic field exposures are associated with an increased risk of a number of health conditions.

If all of the risks that the California Report now associates with magnetic field exposures were indeed to indicate a causal link then such exposure would constitute a significant public health risk. This is why it is important for all sections of society, be they scientists, the general public or Government, to study the California Report in its entirety and consider the implications in terms of public health policy.

Note that the California Report itself extends to 401 pages. If the appendices, comments received and the replies to the comments are included the whole report extends to approximately 1000 pages.