Study type: Epidemiological study (observational study)

Could the geomagnetic field be an effect modifier for studies of power-frequency magnetic fields and childhood leukaemia? epidem.

Published in: J Radiol Prot 2012; 32 (4): 413-418

Aim of study (acc. to author)

A pooled analysis was conducted to investigate whether the geomagnetic field in different countries in which epidemiological studies of power-frequency magnetic fields and childhood leukemia have been performed appears to affect the results of those studies.

Further details

No biophysical mechanism of interaction between the magnetic fields and living systems has yet been identified that is capable of producing significant effects at the sub-microtesla levels implicated by the epidemiological studies on childhood leukemia. A candidate mechanism for a causal link is effects of magnetic fields on biological reactions involving free radicals. It predicts effects from variations in static magnetic fields as well as alternating magnetic fields, and therefore different consequences at different locations on the earth's surface due to variations in geomagnetic field.
The present study is based on the pooled analyses of Ahlbom et al (2000) and Kheifets et al (2010) including following eleven studies: Feychting et al, 1993 (Sweden), Verkasalo et al, 1993 (Finland), Linet et al, 1997 (USA), Michaelis et al, 1997 (Germany), McBride et al, 1999 (Canada), UK Childhood Cancer Study Investigators, 1999 (UK), Schüz et al, 2001 (Germany), Kabuto et al, 2006 (Japan), Malagoli et al, 2010 (Italy), Kroll et al, 2010 (UK), and Wünsch Filho et al, 2011 (Brazil).

Endpoint/type of risk estimation

Type of risk estimation: (odds ratio (OR))

Exposure

Assessment

Exposure groups

Group Description
Group 1 magnetic field exposure ≥ 0.3 µT, respectively 0.4 µT and geomagnetic field

Population

Statistical analysis method:

Conclusion (acc. to author)

The results showed only limited evidence, with wide uncertainty and not statistically significant, of effect modification by geomagnetic field in studies of alternating magnetic fields.

Limitations (acc. to author)

The analysis is limited because, except for the Brazilian study, about which there are methodological questions, all the available studies are from a relatively narrow range of geographic latitudes and hence geomagnetic fields. The spread of geomagnetic fields between the investigated countries is not much greater than typical perturbations to the geomagnetic field within a country.

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