3.2. Pooled analysis of childhood leukaemia and exposure to magnetic fields

The pooled studies on childhood leukaemia and exposure to magnetic fields by Greenland et al. (2000)^[1] and Ahlbom et al. (2000)^[2] played an important role in the classification of low-frequency magnetic fields as “possibly carcinogenic” by the IARC. Two later pooled studies (Schüz et al., 2007 ^[3]; Kheifets et al., 2010^[4]) also found an increased risk of childhood leukaemia. Because new individual studies have been conducted since then, an update of the pooled studies was planned as a research project. In May 2018, a new pooled study was published by Amoon et al.^[5]. In this analysis, there was no overall correlation between the distance to the nearest power line and the risk of childhood leukaemia. Only a distance of less than 50 m from a high-voltage power line of at least 200 kV showed a weak – but not significantly increased – risk of leukaemia. A small, statistically significant increase was observed for children who were younger than five years old at diagnosis and whose home was within 50 m of a high-voltage power line of at least 200 kV. The study could not clarify whether the observed increased risk in the vicinity of high-voltage power lines was due to exposure to magnetic fields. The reason for this is that the strength of the magnetic field was not measured. Instead, the distance of the home to the nearest power line was used as a proxy. Thus, the validity of the study with regard to an association between exposure to magnetic fields and risk of childhood leukaemia is severely limited. The complete statement of the BfS on the Amoon study can be found here.

Because an update of the pooled study is available, the planned study has been cancelled. This decision was presented in the expert workshop held on 25 January 2021 regarding epidemiological studies in the context of power grid expansion and was supported by the experts present.

Literature

[1] Greenland S, Sheppard AR, Kaune WT, Poole C, Kelsh MA. A pooled analysis of magnetic fields, wire codes, and childhood leukemia. Epidemiology 2000; 11:624-634.
[2] Ahlbom A, Day N, Feychting M, Roman E, Skinner J, Dockerty J, Linet M, McBride M, Michaelis J, Olsen JH, Tynes T, Verkasalo PK. A pooled analysis of magnetic fields and childhood leukaemia. Br J Cancer 2000; 83:692-698.
[3] Schüz J, Svendsen AL, Linet MS, McBride ML, Roman E, Feychting M, Kheifets L, Lightfoot T, Mezei G, Simpson J, Ahlbom A. Nighttime exposure to electromagnetic fields and childhood leukemia: an extended pooled analysis. Am J Epidemiol 2007; 166:263-269.
[4] Kheifets L, Ahlbom A, Crespi CM, Draper G, Hagihara J, Lowenthal RM, Mezei G, Oksuzyan S, Schüz J, Swanson J, Tittarelli A, Vinceti M, Wunsch-Filho V. Pooled analysis of recent studies on magnetic fields and childhood leukaemia. Br J Cancer 2010; 103:1128-1135.
[5] Amoon AT et al. Proximity to overhead power lines and childhood leukaemia: an international pooled analysis. Br J Cancer. 2018; 119:364-373. doi: 10.1038/s41416-018-0097-7.