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Temporal variability in residential magnetic fields and risk of childhood leukemia.

Authors
Thomas-D; Jiang-L; London-S; Bowman-J; Peters-J
Source
Thomas D, Jiang L, London S, Bowman J, Peters J, eds., Los Angeles, CA: University of Southern California, 1999 Jun; :1-29
Link
NIOSHTIC No.
20030716
Abstract
Data from a case-control study of childhood leukemia and electromagnetic fields in Los Angeles County were reanalyzed to test hypotheses relating to the temporal variability of the magnetic field's magnitude. Empirical indices of temporal variability such as proportions of time above certain thresholds, frequencies of changes greater than certain amounts, and various auto correlations were computed. We also derived an exposure metric (termed the "kinetic index") from the toxicokinetic model for RNA transcription suggested by Litovitz et al., [1990] to explain experimental results from intermittent magnetic field exposures. None of these indices of time-variability was found to be significantly associated with leukemia risk in univariate analyses. However, when considered jointly, the kinetic index and the first-order autocorrelation were significant, owing to their negative correlation with each other. These results are consistent with the predictions of a modification of the model involving coherence time [Litovitz et al., 1991]. The kinetic index was also marginally significant when adjusted for the Wertheimer-Leeper wire code, but could not account for the risk associated with wire codes. The association with two time-variability indices could be a chance finding, in view of the large number of models tested. Therefore, these results provide only weak support for the hypothesis that the toxicokinetic model and the kinetic index are related to childhood leukemia. However, the approach merits consideration in future epidemiologic studies.
Keywords
Children; Leukemogenesis; Case-studies; Exposure-assessment; Exposure-levels; Exposure-limits; Magnetic-fields; Magnetic-properties; Ribonucleic-acids; Toxic-effects; Toxic-materials; Toxins; Kinetics; Statistical-analysis; Models; Monitoring-systems; Cancer; Cancer-rates
Publication Date
19990601
Document Type
Book or book chapter
Editors
Thomas-D; Jiang-L; London-S; Bowman-J; Peters-J
Fiscal Year
1999
NTIS Accession No.
NTIS Price
NIOSH Division
DBBS
Source Name
Temproal Variability in Residential Magnetic Fields and Risk of Childhood Leukemia
State
OH; CA
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