Is the risk comparison made by the public between EMF and smoking or asbestos a valid one?

The possibility of adverse health effects from exposure to extremely low frequency (ELF) electric and magnetic fields (EMF) has caused considerable controversy in the scientific community and has received great attention in the media and among the general public with many comparing ELF EMF with tobacco smoking and asbestos. Although both smoking and asbestos are now classified by the International Agency for Research on Cancer (IARC) as Group 1 or "established'' carcinogens, this was not always the case. In this paper the evidence for the carcinogenicity of ELF EMF is compared with that for smoking and asbestos using the Bradford Hill model for establishing causality between exposure and disease. Application of the model shows that present data are insufficient to demonstrate that exposure to ELF EMF poses a definite human health hazard. However, while the bulk of the evidence is weak, there are several epidemiological studies which have reported an association between prolonged exposure to magnetic fields at levels above what is normally encountered and an increased risk in childhood leukaemia. On this basis IARC has classified ELF magnetic fields as a Group 2B or "possible'' carcinogen.