Magnetic fields and childhood cancer: an epidemiological investigation of the effects of high-voltage underground cables.
Epidemiological evidence of increased risks for childhood leukaemia from magnetic fields has implicated, as one source of such fields, high-voltage overhead lines. Magnetic fields are not the only factor that varies in their vicinity, complicating interpretation of any associations. Underground cables (UGCs), however, produce magnetic fields but have no other discernible effects in their vicinity. We report here the largest ever epidemiological study of high voltage UGCs, based on 52,525 cases occurring from 1962-2008, with matched birth controls. We calculated the distance of the mother's address at child's birth to the closest 275 or 400 kV ac or high-voltage dc UGC in England and Wales and the resulting magnetic fields. Few people are exposed to magnetic fields from UGCs limiting the statistical power. We found no indications of an association of risk with distance or of trend in risk with increasing magnetic field for leukaemia, and no convincing pattern of risks for any other cancer. Trend estimates for leukaemia as shown by the odds ratio (and 95% confidence interval) per unit increase in exposure were: reciprocal of distance 0.99 (0.95-1.03), magnetic field 1.01 (0.76-1.33). The absence of risk detected in relation to UGCs tends to add to the argument that any risks from overhead lines may not be caused by magnetic fields.
Formerly Childhood Cancer Research Group, University of Oxford, New Richards Building, Old Road Campus, Headington, Oxford, OX3 7LG, UK. National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK.
K J
KJ
Bunch
J
J
Swanson
T J
TJ
Vincent
M F G
MF
Murphy
D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D011211:Electric Power Supplies; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004739:England / Q000453:epidemiology; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D011829:Radiation Dosage; D012042:Registries; D012111:Residence Characteristics; D012307:Risk Factors; D014852:Wales / Q000453:epidemiology