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Residential magnetic fields predicted from wiring configurations: I. Exposure model.

Authors
Bowman-JD; Thomas-DC; Jiang-L; Jiang-F; Peters-JM
Source
Bioelectromagnetics 1999 Oct; 20(7):399-413
NIOSHTIC No.
20027432
Abstract
Case-control data on childhood leukemia in Los Angeles County were reanalyzed with residential magnetic fields predicted from the wiring configurations of nearby transmission and distribution lines. As described in a companion paper, the 24-h means of the magnetic field's magnitude in subjects' homes were predicted by a physically based regression model that had been fitted to 24-h measurements and wiring data. In addition, magnetic field exposures were adjusted for the most likely form of exposure assessment errors: classic errors for the 24-h measurements and Berkson errors for the predictions from wire configurations. Although the measured fields had no association with childhood leukemia (P for trend=.88), the risks were significant for predicted magnetic fields above 1.25 mG (odds ratio=2.00, 95% confidence interval=1.03-3.89), and a significant dose-response was seen (P for trend=.02). When exposures were determined by a combination of predictions and measurements that corrects for errors, the odds ratio (odd ratio=2.19, 95% confidence interval=1.12-4.31) and the trend (p =.007) showed somewhat greater significance. These findings support the hypothesis that magnetic fields from electrical lines are causally related to childhood leukemia but that this association has been inconsistent among epidemiologic studies due to different types of exposure assessment error. In these data, the leukemia risks from a child's residential magnetic field exposure appears to be better assessed by wire configurations than by 24-h area measurements. However, the predicted fields only partially account for the effect of the Wertheimer-Leeper wire code in a multivariate analysis and do not completely explain why these wire codes have been so often associated with childhood leukemia. The most plausible explanation for our findings is that the causal factor is another magnetic field exposure metric correlated to both wire code and the field's time-averaged magnitude.
Keywords
Magnetic-fields; Models; Electrical-transmission; Electrical-properties; Electric-properties; Electrical-fields; Electrical-measurement; Electrical-systems; Electromagnetic-fields; Electromagnetic-radiation; Cancer; Blood-disorders; Children
Contact
J. D. Bowman, NIOSH, 4676 Colombia Pkwy, Cincinnati, OH 45266 USA
CODEN
BLCTDO
Publication Date
19991001
Document Type
Journal Article
Email Address
jdb0@cdc.gov
Fiscal Year
2000
NTIS Accession No.
NTIS Price
Issue of Publication
7
ISSN
0197-8462
NIOSH Division
DART
Source Name
Bioelectromagnetics
State
OH; CA
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