Research

Childhood leukaemia

One of the ways that scientists have researched the possible risk of childhood leukaemia and overhead lines, is by using epidemiology. Epidemiology looks at statistical patterns in human populations, so in this case, it looks at whether more children are diagnosed with leukaemia when they live close to overhead lines compared to those who do not live close by. This type of study can only find associations, not causes, of diseases. To find causes we look to laboratory and mechanistic studies.

Over 40 epidemiological studies have now been performed looking at a possible link between childhood leukaemia and EMFs. Some of those studies found no association with magnetic fields, but many did find associations. Overall, there is a statistical association within the studies that have been performed between high average magnetic fields and childhood leukaemia, although that association has become weaker in recent years.

By contrast, the evidence from the laboratory, through experiments on animals and cells, is that EMFs, at the levels produced by overhead lines, do not show evidence of an increase in childhood leukaemia incidence, or any other effects. No mechanism or way that EMFs could cause childhood leukaemia has been identified. Therefore, the uncertainty is a weak statistical association only and no evidence for causation has been found.

This statistical evidence has led to magnetic fields being classed as a possible cause of cancer by the International Agency for Research on Cancer (IARC)

Summarising the epidemiological evidence

This section summarises some of the major epidemiological studies that have been published to date. The summaries start with pooled analyses. These pool the results from individual studies and calculate a single overall result, giving the results more statistical significance. These studies have been carried out over a number of years and demonstrate how the statistical association has become weaker.