Purpose: Epidemiological studies have found an association between exposure to extremely low-frequency magnetic fields (ELF-MF) and childhood leukemia. In 2005, a large British study showed an association between proximity of residence to high-voltage power lines and the risk of childhood leukemia. The association extended beyond distances at which the 'power line'-induced magnetic fields exceed background levels, suggesting that the association was not explained by the magnetic field, but might be due to chance, bias, or other risk factors associated with proximity to power lines. Our aim was to conduct a comparable study in an independent setting (Denmark).
Methods: We included 1,698 cases aged <15, diagnosed with leukemia during 1968-2006, from the Danish Cancer Registry and 3,396 controls randomly selected from the Danish childhood population and individually matched by gender and year of birth. We used geographical information systems to determine the distance between residence at birth and the nearest 132-400 kV overhead power line.
Results: Odds ratios (ORs) were 0.76 [95 % confidence interval (CI) 0.40-1.45] for children who lived 0-199 m from the nearest power line and 0.92 (95 % CI 0.67-1.25) for those who lived 200-599 m away when compared with children who lived ≥600 m away. When restricting the analysis to 220 and 400 kV overhead power lines, the OR for children who lived 200-599 m from a power line was 1.76 (95 % CI 0.82-3.77) compared to children who lived ≥600 m away. However, chance is a likely explanation for this finding as the result was not significant, numbers were small, and there were no indications of an higher risk closer to the lines since no cases were observed within 200 m of these.
Conclusions: We found no higher risk of leukemia for children living 0-199 m or for children living 200-599 m of a 132-400 kV overhead power line. A slightly elevated OR for children living between 200 and 599 m of a 220-400 kV overhead power line is likely to be a chance finding.