Am J Epidemiol 2004; 159:1201.
Copyright © 2004 by the Johns
Hopkins Bloomberg School of Public Health
LETTERS TO THE EDITOR |
RE: "USE OF ELECTRIC BEDDING DEVICES AND RISK OF BREAST CANCER IN AFRICAN-AMERICAN WOMEN"
Department of Preventive Medicine, School of Medicine, Stony Brook University, Stony Brook, NY 11794-8036
In their analysis of electric bedding devices, Zhu et al. (1) included participants who used the blanket only to warm the bed as well as those who kept the blanket on most of the time while in bed when reporting on the effect of "number of years of use" and "number of seasons per year."
Since women who kept it on most of the time while in bed have a higher and longer magnetic field exposure than do women who used the blanket only to warm the bed, we suggest that the authors either 1) stratify the duration and number of seasons of use by mode of use or, preferably, 2) limit the analyses only to women who kept the device on most of the time in bed. This approach was followed by all but one of the published studies that collected information on mode of use. In these studies, analyses stratified the results on duration and frequency of use by mode of use (2), or they either excluded women who used the blanket to warm the bed only (3, 4) or only considered longer duration of exposure to electric blankets/bed warming devices as use during their sleep time (5–10). The study by Gammon et al. (2) was the only one to show the duration of use results stratified by mode of use; no difference in risk was shown. The one study that included both modes of use in the duration analyses did not find an association between electric blanket use and breast cancer (11). Since the other seven studies did not show (3, 4) or were unable to show (5–10) their results stratified by mode of use, there is no way of knowing if the results would have differed across these strata.
We would be very interested in the results of these analyses.
REFERENCES
- Zhu K, Hunter S, Payne-Wilks K, et al. Use of electric bedding devices and risk of breast cancer in African-American women. Am J Epidemiol 2003;158:798–806.
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- Laden F, Neas LM, Tolbert PE, et al. Electric blanket use and breast cancer in the Nurses’ Health Study. Am J Epidemiol 2000;152:41–9.
[Abstract/Free Full Text] - McElroy JA, Newcomb PA, Remington PL, et al. Electric blanket or mattress cover use and breast cancer incidence in women 50–79 years of age. Epidemiology 2001;12:613–17.[CrossRef][ISI][Medline]
- Zheng T, Holford TR, Mayne ST, et al. Exposure to electromagnetic fields from use of electric blankets and other in-home electrical appliances and breast cancer risk. Am J Epidemiol 2000;151:1103–11.
[Abstract/Free Full Text]
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