ELECTROMAGNETIC-FIELDS AND NEOPLASMS WITH SPECIAL REFERENCE TO EXTREMELY LOW-FREQUENCIES

The available documentation from epidemiologic and experimental investigations that indicates links between exposure to extremely low frequency (ELF) electromagnetic fields (EMFs) and cancer development has been evaluated in search of possible causal relationships. Of 29 epidemiologic studies published in the last decade 22 indicate increased risk of neoplasms in residents living in houses with an above-average background 50/60 Hz magnetic field flux (above 3 mG), or in certain occupations with probable exposure to EMFs during work. The strength of association and consistency were found reasonably convincing, while temporal relationships to past EMF exposure of cancer victims is not satisfactorily documented in the retrospective epidemiologic studies. Experimental evidence for the possible cancer-promoting properties of ELF EMFs arose only from studies of cellular effects in vitro; there are no acceptable animal studies offering convincing evidence for or against links between ELFs and carcinogenesis. Single cellular studies indicate that weak ELFs (or ELF-modulated microwave fields) may exert effects similar to chemical cancer promoters (e.g. phorbol esters) or enhance the promoting capability of these chemicals. Two theories try to explain mechanisms for the possible cancer-related properties of ELF EMFs, but neither are supported by acceptable experimental evidence. Lack of data from animal experiments further lowers support for the above theories. In summary, it is proposed that the available information only allows ELF EMFs to be classed as possible carcinogens for humans. Animal experiments, as well as prospective epidemiologic studies with more closely defined exposure conditions are needed in order to progress the understanding of health risks related to environmental and occupational EMF exposure.