AUTHOR: Edward P. Washburn et al.
Cancer Causes and Control. 1994:(5) p. 299-309.
STUDY DESIGN: A meta-analysis was conducted to address the question whether residential proximity to electricity transmission and distribution equipment is associated with increased risk of childhood leukemia, childhood lymphoma, and childhood nervous system tumors. Analyses were conducted based on 13 studies for leukemia, 5 studies for lymphoma, and 7 studies for nervous system tumors. Studies analyzed had to meet specific criteria. Studies were "double-masked," a procedure which is designed to eliminate bias when determining which studies to include.
CONCLUSIONS: The combined relative risks are as follows: for childhood leukemia (RR=1.49, 95% CI=1.11-2.00), for childhood lymphoma (RR=1.58, 95% CI=0.91-2.76), which was not statistically significant, and for childhood nervous system tumors (RR=1.89, 95% CI=1.34-2.67). Formal analysis of dose-response relationships was not possible due to limited dose-response data. The authors call for future research which should include more precise exposure assessment and which should address what specific EMF characteristics are having a biological effect.
LIMITATIONS: Exposure assessment in the studies analyzed was found to be imprecise which increases the opportunity for misclassification, especially when exposure to EMF is measured by proxy. This may result in either greater or lesser estimate of the relative risk. Residential proximity was not the same for all the studies analyzed. Cancer outcomes were not always coded uniformly in the studies analyzed. Socioeconomic status may have been a bias in many of the primary studies.