The UK electricity industry supports research into the health of its own workers. A database has been set up of everyone who worked for the then Central Electricity Generating Board (CEGB) in the late 1970s, over 80,000 people. All these people are being followed up to identify, when they eventually die, the cause of death. New techniques have been developed for assessing people’s exposure to magnetic fields over their working life. It is then possible to see whether the cause of death is linked to exposure to magnetic fields.
A major expansion of the use of this cohort is the decision in 2009 to start collecting data on cancer incidence, not just on causes of death.
Results so far
Analyses so far have shown no association between leukaemia, brain cancers, heart disease or neurodegenerative disorders and magnetic fields:
The first publication in 1997 looked at magnetic fields and brain cancer, and concluded:
“Although the exposure categorisation was based solely on recent observations, the study findings do not support the hypothesis that the risk of brain cancer is associated with occupational exposure to magnetic fields.” Full abstract
The second publication in 2001 used a new method for exposure assessment, developed by scientists at National Grid. This exposure assessment is now more sophisticated than used in most previous studies of this type (more details). The paper looked at magnetic fields and leukaemia, and concluded:
“There are no discernible excess risks of leukaemia as a consequence of occupational exposure to magnetic fields in United Kingdom electricity generation and transmission workers.” Full abstract
The third publication, also in 2001, used the improved exposure assessment to reanalyse the data on brain cancers, and concluded:
“There are no discernible excess risks of brain tumours as a consequence of occupational exposure to magnetic fields in United Kingdom electricity generation and transmission workers.” Full abstract
The fourth publication, in 2004, looked at heart disease, and concluded:
“There are no discernible excess risks of mortality from cardiovascular diseases as a consequence of occupational exposure to magnetic fields in UK electricity generation and transmission workers.” Full abstract.
A follow-up publication concluded that death certificates have only very limited accuracy at distinguishing different types of heart disease, and therefore some of the previous epidemiological studies of EMFs and heart disease are methodologically suspect.
The fifth publication, in 2005, compared mortality in the group as a whole with the general population, and concluded:
“Mortality was exceptionally low for most causes of death but late health effects from earlier asbestos exposure were still in evidence.”Full abstract
The sixth publication, in 2007, looked at neurodegenerative disorders (Alzheimer's disease, motor neurone disease and Parkinson's disease) and concluded:
“There is no convincing evidence that UK electricity generation and transmission workers have suffered increased risks from neurodegenerative diseases as a consequence of exposure to magnetic fields.”Full abstract
Future directions
Although not directly part of the research based on this cohort, the UK electricity industry sponsored a workshop in Edinburgh in 2006 for the people involved in these studies and in similar work in other countries to discuss possible future directions for such research. The conclusions were published in a peer-reviwed paper.