![]() Geographic information systems, maps and on-site measurements have all been used to assess proximity to power lines 16, each with varying degrees of accuracy. Thus, the existence of similar temporal trends in risk in other countries is unresolved. Both studies covered more recent time periods only (diagnosed in 1988 or later). In these studies, no increase in risk was observed beyond 50 m from 200 + kV lines or within 50 m of lower voltage lines. Two large studies in France and the United States, specifically California, reported that living within 50 m of a 200 + kV line may be associated with a small increased risk of childhood leukaemia 14, 15. A small Danish study of calculated fields also found higher risks in earlier decades (1968–1986) compared with more recent cases (1987–2003) 13. The updated study confirmed the raised leukaemia risks reported for the earlier decades, but found that risk declined in the latest decades. 8 was extended to cover more recent time periods (diagnoses during 1962–2008) and lower line voltages 12. Several explanations have been proposed, including selection of controls, but none are fully satisfactory 11, leaving open the possibility that some factor associated with distance other than MF is responsible. Whether the risk truly persists at greater distances from power lines and what might be an explanation for this observation is unclear. 8, reporting on a study in the United Kingdom (UK) using diagnosed cases from 1962–1995, found an association between childhood leukaemia and the distance between home address at birth and the nearest high-voltage overhead line 8 with the apparent risk extending out to 600 m, a distance greater than would be expected for MF from high-voltage lines, because MF rapidly decline with distances and are very weak at distances beyond 100 m 9, 10. Unlike MF, there has not yet been a comprehensive pooled analysis on childhood leukaemia and distance to power lines, which could help to answer this question.ĭraper et al. However, distance is known to be a poor predictor of MF exposure 7 and therefore the question arises as to whether the association of increased childhood leukaemia risk with distance is due to MF or to other factors associated with distance from overhead power lines that are unrelated to long-term average MF. High MF can occur close (e.g., < 100 m) to high voltage power lines 6. They found an odds ratio (OR) of 1.59 (95% confidence interval (CI): 1.02–2.50) for the closest distance category, which was comparable to the result for MF. 4 pooled six studies for an analysis of the association between distance from power lines and childhood leukaemia. ![]() In one of these analyses, Kheifets et al. Analyses that have pooled data from multiple studies 2, 3, 4, 5 report a small but consistent increased risk of childhood leukaemia associated with exposures above 0.3 or 0.4 μT. Thirty-five epidemiologic studies have examined the association between exposure to extremely low-frequency magnetic fields (MFs) and childhood leukaemia 1. Reasons for the increased risk, found in this and many other studies, remains to be elucidated. In this first comprehensive pooled analysis of childhood leukaemia and distance to power lines, we found a small and imprecise risk for residences < 50 m of 200 + kV lines that was not explained by high magnetic fields. Odds ratios remained unchanged with adjustment for potential confounders. There was no association with calculated magnetic fields. The odds ratio was higher among children diagnosed before age 5 years. ![]() Among children living < 50 m from 200 + kV power lines, the adjusted odds ratio for childhood leukaemia was 1.33 (95% CI: 0.92–1.93). There was no material association between childhood leukaemia and distance to nearest overhead power line of any voltage. We present a pooled analysis combining individual-level data (29,049 cases and 68,231 controls) from 11 record-based studies. We pooled data from multiple studies to assess the association with distance and evaluate whether it is due to magnetic fields or other factors associated with distance from lines. Although studies have consistently found an association between childhood leukaemia risk and magnetic fields, the associations between childhood leukaemia and distance to overhead power lines have been inconsistent. ![]()
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