Childhood leukaemia

Around 20 epidemiological studies have now been performed looking just at a possible link between childhood leukaemia and EMFs. Scientific papers have an abstract and you can read the abstracts of the more important epidemiological studies here. Some of those studies found no association with magnetic fields, but most have found associations. Overall there is a statistical association within the studies that have been performed between unusually high magnetic fields and childhood leukaemia. By contrast, the evidence from the laboratory is that low level EMFs of the type experienced by the public do not seem to have the harmful effects that have been claimed.

Most studies have looked at whether EMFs cause childhood leukaemia but one recent study has looked at whether magnetic fields affect survival from leukaemia. One study has looked at children with Down's syndrome rather than children in general.

What do the studies show?

Associations from epidemiological studies on their own do not establish causation (More on what epidemiology can or cannot show). The associations could be caused by two other things:

• Bias in the study. If the children chosen to take part in the study were not properly representative of the population as a whole, the association that was found in the study might not exist in the rest of the population. We know that this problem (often called “control selection bias”) exists in most of the studies; what we don’t yet know is exactly how significant it is. More on bias.
• Other factors which were not properly controlled for. Something which does actually cause childhood cancer might be associated with magnetic fields so that children are exposed to both at once. Then the association that the study found would be caused by the other factor and not by EMFs. This is known as a “confounding factor”. We list here some of the other factors which vary with magnetic fields.

Evidence in summary

Overall, the evidence is strong enough for the official classification (by IARC and WHO) to be "possibly" a cause of cancer, the middle of 5 categories more on the IARC categories.

How many children may be affected?

The HPA calculate that the raised risk for childhood leukaemia suggested by epidemiological studies, if it were real, would correspond roughly to an extra two cases of childhood leukaemia per year in the UK, compared to an annual total of around 500 cases. More on numbers of children and cases.

Key studies

Click here fr the abstracts of the dozen or so most important studies on childhood leukaemia.

Click here for a summary of some key results: the Ahlbom pooled analysis, and two studies from the UK, the UKCCS and the "Draper" study.

Conclusions of expert review groups

Click here for the conclusions of some of the key expert reviews who have looked at the evidence on childhood leukaemia.