Authored By:
Sudan M, Arah OA, Becker T, Levy Y, Sigsgaard T, Olsen J, Vergara X and Kheifets LThis is a cohort study which investigated any association between exposure to extremely low frequency (ELF) magnetic fields early in life and asthma in children. A total of 92,676 child and mother pairs were included in the study. The children’s exposures were estimated at the mothers’ residences during pregnancy and at the children’ residences from birth until diagnosis/end of follow up (estimations were based on distance from transmission lines and transmission line configuration details).The study did not find any statistically significant results that indicated an increased risk of asthma in children exposed to different levels of ELF magnetic fields. The authors concluded that there is no association between ELF magnetic fields exposure and asthma in children.
Published In:
PLoS One 2017; 12 (5): e0177651One of the major limitations of epidemiological studies investigating residential ELF magnetic fields exposure lies with the tiny proportion of study participants being exposed above the normal background level i.e. above .3 or .4 microtesla (µT). This leads to a low statistical power to reliably detect any association. ELF magnetic fields above .3 or .4 µT were shown by some epidemiological studies to be associated with childhood leukaemia – association that has not been established up until now. For example, the study by Sudan et al found that the proportion of subjects exposed above .2 µT was only 0.05%.
The Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) in its opinion on potential health effects of exposure to electromagnetic fields in 2015 reported that there were recent studies that found an increased risk of asthma in the offspring associated with exposure to ELF magnetic fields during pregnancy. One major study that found this was a prospective cohort study conducted by Li et al (2011). SCENIHR concluded that even though recent studies for the first time have shown an association between ELF magnetic fields exposure and asthma, the results need to be reproduced to evaluate their significance for risk assessment. It was interesting to note that the study by Sudan et al was designed to replicate the study by Li et al; however the study by Sudan et al did not reproduce the results found by Li et al.
