Exposure from power lines
Although a study in 1979 pointed to a possible association between living near electric power lines and childhood leukemia (5), more recent studies have had mixed findings. Currently, researchers conclude that there is little evidence that exposure to ELF-EMFs from power lines causes leukemia, brain tumors, or any other cancers in children (1, 6–10).
Exposure in homes
Many studies have also looked for possible associations between magnetic fields measured in homes and residences and the risk of childhood cancers, especially leukemia. Individual studies have had varying results, but most have not found an association or have found it only for those children who lived in homes with very high levels of magnetic fields, which are present in few residences (11–14).
To develop the most accurate estimates of the risks of leukemia in children from magnetic fields in the home, researchers have analyzed the combined data from many studies. In one such analysis that combined data from nine studies done in several countries, leukemia risk was increased only in those children with the highest exposure (a category that included less than 1 percent of the children); these children had a twofold excess risk of childhood leukemia (15). In another analysis that combined data from 15 individual studies, a similar increase in risk was seen in children with the highest exposure level (16). A more recent analysis of seven studies published after 2000 found a similar trend, but the increase was not statistically significant (17).
Overall, these analyses suggest that if there is any increase in leukemia risk from magnetic fields, it is restricted to children with the very highest exposure levels. But it is possible that this increase is not real, because if magnetic fields caused childhood leukemia, certain patterns would have been found, such as increasing risk with increasing levels of magnetic field exposure. Such patterns were not seen.
Another way that people can be exposed to magnetic fields in the home is from household electrical appliances. Although magnetic fields near many electrical appliances are higher than those near power lines, appliances contribute less to a person’s total exposure to magnetic fields because most appliances are used only for short periods of time. Again, studies have not found consistent evidence for an association between the use of household electrical appliances and risk of childhood leukemia (18).
Parental exposure and risk in children
Several studies have examined possible associations between maternal or paternal exposure to high levels of magnetic fields before conception and/or during pregnancy and the risk of cancer in their future children. The results to date have been inconsistent (19, 20). Studies are ongoing to evaluate this question.
Exposure and cancer survival
A few studies have investigated whether magnetic field exposure is associated with prognosis or survival of children with leukemia. Several small retrospective studies of this question have yielded inconsistent results (21–23). An analysis that combined prospective data for more than 3000 children with acute lymphoid leukemiafrom eight countries showed that ELF magnetic field exposure was not associated with their survival or risk ofrelapse (24).