ARPANSA - Australian Radiation Protection and Nuclear Safety Agency

Introduction

Linet et al pooled the data from several epidemiological studies on powerline magnetic fields and health, in order to improve the statistics and so improve the quality of the results. In all, 9 studies were combined from various countries throughout the world. The combined study included 3247 cases and 10,400 controls and investigated the association between magnetic field exposure and childhood leukemia.

Results

Magnetic field exposure levels < 0.4 µT (0.4 micro Tesla = 4 milliGauss) to which 99.2% of the study children were exposed showed no increased risk. Childen exposed to levels higher that 0.4 µT showed twice the risk (95% CI 1.27 - 3.13) of contracting leukemia as those who were not so exposed.

Discussion

Less than 1% of children were in the high exposure group so the statistics here are not so strong. Adjusting for potential confounders such as level of urbanization and level of traffic exhaust failed to change the findings.

This type of study is subject to errors associated with measuring exposure. Some of the individual studies from the pool used calculated exposures based on external powerline configurations and not actual measurements based in the home. In addition no account was taken of the latency period for induction of childhood leukemia. That is the time taken from exposure to a possible carcinogen and the appearance of clinical disease.

Conclusion

The authors concluded that since only a small fraction of the children were highly exposed and that since the exposure errors for these cannot be determined they could not determine what was causing the risk.

Nevertheless for exposures above 0.4 µT the risk of childhood leukemia was doubled. Selection bias (choice of study participants) was considered a possible cause of the increase.

Related ARPANSA Links

Residential Exposure to Magnetic Fields and Acute Lymphoblastic Leukemia in Children.
The United States National Institute of Environmental Health Sciences (NIEHS) Conclusion on Health Effects of Electric and Magnetic Fields
50Hz Electric and Magnetic Fields
The Controversy Over Electromagnetic Fields and Possible Adverse Health Effects
Distance of Place of Residence from Dense Traffic; An Alternative to 50Hz Magnetic fields as a Risk Factor for Leukemia and Other Childhood Cancers?
Powerline (Extremely Low Frequency ELF) Electromagnetic Fields and Cancer - The Doll Report

Related links

• See the ABC interview of a researcher in the field.
• Non Ionising Radiation Links

References

A Pooled Analysis Study of Magnetic Fields and Childhood Cancer
British Journal of Cancer
2000, 83:692-698.
A. Ahlbom., M.Linet et al

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