BENER Abstract No. 15127. EXTRA LOW FREQUENCY ELECTRIC AND MAGNETIC FIELDS IN THE BEDPLACE OF CHILDREN DIAGNOSED WITH LEUKEMIA: A CASE-CONTROL STUDY.
(Eng.) Coghill, R. W.; Steward, J.; Philips, A. [Coghill Res. Labs., Lower Race, Gwent NP4 5UH, UK (RR/R.C.); Gwent Health Commission, Mamhilad, Pontypool, Gwent, UK (J.S.); Delta-T Devices Ltd., Burwell, Cambridge, UK (A.P.)] Eur J Cancer Prev 5(3):153-158; 1996 (26 Refs).
The authors surveyed extremely low-frequency (ELF) electric and magnetic field exposures in the bedrooms of children with leukemia. The survey was conducted using a case-control design. Electric and magnetic fields were measured as close to the bed as possible of 56 children, 33 boys, under the age of 15 yr who had been diagnosed with acute lymphocytic leukemia (ALL) within 10 yr of March 1995 and 56 children, matched for age and sex, without ALL. The subjects lived in southeastern England. Cases were identified through media requests and selection from charity databases which, the authors indicated, could have introduced a selection bias. The fields were measured by 5 trained assistants using custom-built electric and magnetic field probes, built to IEEE and International Electrotechnical Commission recommendations, connected to data loggers (Delta-T Devices, Burwell, UK). The measurements were taken every 30 sec and averaged every 5 min over a 24-hr period. From these measurements, data were extracted for the period between 2000 and 0800 hr on the assumption that this period, at least, conservatively, represented the most relevant period of exposure. The mean 24-hr ELF magnetic fields and standard deviations measured in the bedrooms of the children with ALL and the controls were 0.070 +/- 0.070 and 0.057 +/- 0.038 uT, respectively. The difference was not statistically significant. The 24-hr mean vertical component of the ELF electric fields in the bedrooms of the case children and controls was 13.5 +/- 13.4 and 7.3 +/- 12.9 V/m, respectively. The mean 12-hr vertical component of the electric fields, based on measurements made between 2000 and 0800 hr, was 13.9 +/- 13.6 V/m for the children with ALL and 7.3 +/- 12.9 V/m for the controls. The difference between the 12 and 24-hr average electric fields of cases and controls was statistically significant (p<0.01). A more detailed analysis of the 12-hr average electric field data showed that 13 cases and 5 controls were exposed to field strengths of 20 V/m or higher, 14 cases and 8 controls were exposed to 10 to 19-V/m electric fields, 12 cases and 13 controls were exposed to electric field strengths of 5 to 9 V/m, and 17 cases and 30 controls were exposed to electric field strengths below 5 V/m. For all cases and controls, 12-hr exposure to electric fields of 10 V/m or higher was associated with an increased risk of ALL, relative risk (RR) = 2.86 (95% confidence interval (CI) 1.16-8.00). A dose-response gradient was seen when cut-off points of 5 to 9, 10 to 19, and 20 V/m were used. The corresponding RRs were 1.49 (CI 0.47-5.10), 2.40 (CI 0.79-8.09), and 4.69 (CI 1.17-27.78). The authors concluded that this study, which was the first to report periodic electric field exposures in the habitual bedplace of leukemic children, found significant differences in the exposure of leukemic vs. non-leukemic children. This suggests that the importance of electric fields may have been overlooked in previous epidemiological studies of EMFs and cancer.
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