This volume evaluates possible carcinogenic hazards from exposures to static and extremely low frequency (ELF) electric and magnetic fields. It is the first of two IARC Monographs volumes on various kinds of non-ionizing radiation. Extremely low frequency (ELF) magnetic field exposures result from proximity to electric power transmission lines, household wiring, and electric appliances and are in addition to the exposure that results from the earth's magnetic field. Overall, extremely low frequency magnetic fields were evaluated as possibly carcinogenic to humans (Group 2B). Static magnetic fields and static and extremely low frequency electric fields could not be classified as to carcinogenicity to humans (Group 3).