Exposure to Magnetic Fields and Childhood Leukemia: An Overview of Meta-Analysis

Background: Leukemia is the most common cancer in children. We aimed to evaluate the association between exposure to magnetic fields and childhood leukemia. Materials and Methods: In this overview, the relevant articles evaluating the association between exposure to magnetic fields and childhood leukemia are screened on the electronic databases of Scopus, EMBASE, Cochrane, Web of Science, and Medline until February 10, 2019. Results: The first meta-analysis showed a statistical association between the magnetic field intensity of ≥0.4 μT and ≥0.2 μT and childhood leukemia. The second meta-analysis based on wiring configuration codes resulted in a pooled relative risk estimate of 1.46 (95% CI=1.05-2.04 μT, P=0.024) and 1.59 (95% CI=1.14-2.22 μT, P=0.006) for exposure to 24-h measurements of magnetic fields, indicating a potential effect of residential magnetic field exposure on childhood leukemia. In the third meta-analysis, the odds ratios of exposure categories of 0.1-0.2 μT, 0.2-0.3 μT, and ≥0.3 μT over <0.1 μT were 1.07 (95% CI=0.81-1.41 μT), 1.16 (95% CI=0.69-1.93 μT), and 1.44 (95% CI=0.88-2.36 μT), respectively. In contrast to the three meta-analyses, there was no statistically significant association between exposure to ≥ 0.1μT and childhood leukemia. In addition, no significant difference was observed between two groups of children living at a distance of <100 m from the source point of magnetic fields and those living at a distance of ≥ 100 m (OR=1.34; 95% CI=0.98-1.83). Conclusion: Three meta-analyses showed a statistical association between magnetic field intensity and childhood leukemia (ranged 0.1-2.36 μT). The results of one study also showed that there was no relationship between exposure to ≥ 0.1 μT and childhood leukemia.