Power frequency magnetic fields and risk of childhood leukaemia: misclassification of exposure from the use of the 'distance from power line' exposure surrogate.
A recent study examining the relationship between distance to nearby power lines and childhood cancer risk re-opened the debate about which exposure metrics are appropriate for power frequency magnetic field investigations. Using data from two large population-based UK and German studies we demonstrate that distance to power lines is a comparatively poor predictor of measured residential magnetic fields. Even at proximities of 50 m or less, the positive predictive value of having a household measurement over 0.2 microT was only 19.4%. Clearly using distance from power lines, without taking account of other variables such as load, results in a poor proxy of residential magnetic field exposure. We conclude that such high levels of exposure misclassification render the findings from studies that rely on distance alone uninterpretable.
Maslanyj
Myron
M
EMF Dosimetry Group, Radiation Protection Division, Centre for Radiation, Chemical and Environmental Hazards, Health Protection Agency, Chilton, Didcot, Oxon, UK.
Simpson
Jill
J
Roman
Eve
E
Schüz
Joachim
J
D002648:Child; D011211:Electric Power Supplies / Q000009:adverse effects*; D004574:Electromagnetic Fields; D004781:Environmental Exposure / Q000009:adverse effects*; D005858:Germany; D006798:Housing; D006801:Humans; D007938:Leukemia / Q000453:epidemiology*; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D012306:Risk; D018570:Risk Assessment; D012307:Risk Factors; D006113:United Kingdom