The relative merits of contemporary measurements and historical calculated fields in the Swedish childhood cancer study.
We present arguments that suggest that historical average calculated fields, which are widely used to estimate biologically relevant exposure to electromagnetic fields, may be less accurate than contemporary spot measurements, which are made at a time following the biologically relevant period of exposure. We use data from the seminal Feychting and Ahlbom study of the health effects of electromagnetic field exposure in a Swedish population to illustrate our argument. We also show how the two types of measurements can produce divergent estimates of risk, and show how in the Feychting and Ahlbom study, the less accurate measurement, the historical average calculated fields, may have resulted in a spurious increase in the estimates of risk. Finally, we consider the implications of our arguments for other studies that rely on wire codes and historical calculations of personal exposure.
Jaffa
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PacifiCorp, Salt Lake City, UT 84140, USA.
Kim
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Aldrich
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TE
D015982:Bias; D002648:Child; D004574:Electromagnetic Fields / Q000009:adverse effects; D004781:Environmental Exposure / Q000009:adverse effects; D015340:Epidemiologic Research Design; D006801:Humans; D009369:Neoplasms / Q000453:epidemiology*; D013548:Sweden / Q000453:epidemiology