Authored By:
Zhang Y, Lai J, Ruan G, Chen C, Wang DWMeta-analysis of epidemiological studies that investigated the association between extremely low frequency (ELF) electromagnetic fields (EMF) and cancer risk. A total of 42 case-control studies involving 13,259 cases and 100,882 controls were included. The overall analysis of the pooled data found that there is a small increased cancer risk (odds ratio, OR = 1.08; 95% confidence interval, 95% CI = 1.01-1.15). In subgroup analyses increased risks were shown in interview-based studies compared to measurement-based studies, in North American studies compared to European studies and residential studies compared to occupational studies. The authors concluded that there is an association between ELF EMF exposure and cancer.
Published In:
Environ Int 2015; 88 : 36 – 43The study by Zhang et al is one of the first meta-analysis to include all of the eligible case-control studies on ELF EMF exposure and cancer. Although the authors found an overall statistically significant association, the association is very small. Furthermore the authors assign subjects as being exposed at lower exposure levels, which could account for the results. Another methodological problem with this paper is that it combines both occupational and residential studies for the overall result; although separate associations are also provided.
The overall evidence for an association between ELF magnetic field exposure and the risk of female breast cancer as well as adult brain cancer and leukaemia is weak and remains inadequate (see World Health Organization’s Environmental Health Criteria no. 238, http://www.who.int/entity/peh-emf/publications/Complet_DEC_2007.pdf). The exception is with leukaemia in children, the new epidemiological studies published after the WHO’s review are continuing to be consistent with earlier findings of a possible increased risk of childhood leukaemia with exposures higher than typically encountered by the public (Scientific Committee on Emerging and Newly Identified Health Risks). However, it is not known how magnetic fields could cause childhood leukaemia. In addition, other research including studies on cells and animals has not confirmed these results. On balance, the evidence related to childhood leukaemia is not strong.
