3.9. Case-control study on childhood leukaemia and low-frequency magnetic fields from traction current installations

In the 1990s, a case-control study was conducted to investigate a possible correlation between childhood leukaemia and residential exposure to low-frequency magnetic fields (16.7 Hz) in Germany (Schüz et al. 2001). Here, 16.7 Hz corresponds to the frequency at which traction current installations are also operated. The study includes 489 childhood leukaemia cases and 1,240 controls. Exposure was determined by taking measurements in the child’s bedroom over a 24-hour period. Comparing the group with a low median magnetic field exposure of < 0.1 µT versus the group with a high median magnetic field exposure of ≥ 0.2 µT, the study reported an increased but statistically not significant odds ratio of 1.91 (95 % CI: 0.41–8.89). The clearest limitation of the study is that the proportion of medium- or high-exposed persons was only 1 % (cases) or 1.9 % (controls) of the study population. The informative value of the study is thus very limited.

Another study investigated the relationship between the distance of the place of residence to the nearest traction current installation and the incidence of childhood leukaemia or non-Hodgkin’s lymphoma in England and Wales (Dickinson et al. 2003). This study also found a slight but statistically not significant association between the density of traction current installations and the risk of disease (rate ratio = 1.001; 95 % CI: 1.000–1.003). However, the authors do not rule out the possibility that this result is also due to another parameter, the “population mixing factor” which represents the extent of infections present in a region. Even with this study, there is therefore no clear statement about a possible association between childhood leukaemia and residential exposure to extremely low-frequency magnetic fields in the 16.7 Hz frequency range of traction current installations.

For this reason, the research project planned here will again investigate a possible association between the proximity of the place of residence to an electrified railway line and the risk of the occurrence of childhood leukaemia. The possibilities of such an investigation were presented at the expert workshop held on 25 January 2021 regarding epidemiological studies in the context of power grid expansion and were discussed with the experts present. For this research question a case-control study is suitable and data on cases of childhood leukaemia could be collected from the German Childhood Cancer Registry. For exposure assessment, the distance to the nearest traction current installation shall be determined. Based on the data collected in the previous study (Schüz et al. 2001), exposure to low-frequency magnetic fields could be estimated from these distance data.

It is currently being examined whether a study in this form is possible.

Literature

Dickinson HO, Hammal DM, Dummer TJ, Parker L, Bithell JF. Childhood leukaemia and non-Hodgkin's lymphoma in relation to proximity to railways. Br J Cancer. 2003 Mar 10;88(5):695-8. doi: 10.1038/sj.bjc.6600762. PMID: 12618876; PMCID: PMC2376356.

Schüz J, Grigat JP, Brinkmann K, Michaelis J. Childhood acute leukaemia and residential 16.7 Hz magnetic fields in Germany. Br J Cancer. 2001 Mar 2;84(5):697-9. doi: 10.1054/bjoc.2000.1630. PMID: 11237393; PMCID: PMC2363785.