Bioelectromagnetics31:89^101(2010) Review ExtremelyLowFrequencyElectricFieldsand Cancer:AssessingtheEvidence Leeka Kheifets, 1 * David Renew, 2 Glenn Sias, 3 and John Swanson 2 1 UCLA Schoolof Public Health, Department of Epidemiology, LosAngeles, California 2 National Grid, London, UK 3 Southern California Edison, anEdisonInternational Company, Rosemead, California Much of the research and reviews on extremely low frequency (ELF) electric and magnetic fields (EMFs) have focused on magnetic rather than electric fields. Some have considered such focus to be inappropriate and have argued that electric fields should be part of both epidemiologic and laboratory work. This paper fills the gap by systematically and critically reviewing electric-fields literature and by comparing overall strength of evidence for electric versus magnetic fields. The review of possible mechanisms does not provide any specific basis for focusing on electric fields. While laboratory studies of electric fields are few, they do not indicate that electric fields should be the exposure of interest. The existing epidemiology on residential electric-field exposures and appliance use does not support the conclusion of adverse health effects from electric-field exposure. Workers in close proximity to high-voltage transmission lines or substation equipment can be exposed to high electric fields. While there are sporadic reports of increase in cancer in some occupational studies, these are inconsistent and fraught with methodologic problems. Overall, there seems little basis to suppose there might be a risk for electric fields, and, in contrast to magnetic fields, and with a possible exception of occupational epidemiology, there seems little basis for continued research into electric fields. Bioelectromagnetics 31:89–101, 2010. ß 2009 Wiley-Liss, Inc. Key words: review; EMF; childhood Leukemia INTRODUCTION Given the ubiquitous nature of extremely low frequency (ELF) electric and magnetic fields (EMFs), there has been concern regarding their potential to adversely affect health. At these extremely low frequencies, electric and magnetic fields are separate entities which must be considered separately. Following an early focus on electric fields and nonspecific health endpoints in the 1970s, from the 1980s onward much of the research has focused on magnetic fields and cancer rather than electric fields. This focus evolved partly because electric fields are harder to measure and characterize, but mainly because of the scientific leads provided by the early magnetic-field epidemiological studies that arose at that time. Nevertheless, some have considered the focus on the magnetic field to be inappropriate and have argued that electric fields should be part of both epidemiologic and laboratory work [Henshaw et al., 1996; Coghill, 2005]. Draper et al. [2005] found an association between childhood leuke- mia and residential proximity to power lines at distances that extend well beyond the expected influence of magnetic fields from transmission lines. Among numerous interpretations of this unexpected finding, electric field was suggested as a previously ignored candidate [Coghill, 2005]. Numerous previous reviews largely focused on magnetic fields [IARC, 2002; WHO, 2007]. Specifically, IARC placed ELF electric fields in category 3 (‘‘inadequate evidence’’) at the same time as placing ELF magnetic fields in category 2B (‘‘possibly carcinogenic’’), but most of their focus was on magnetic fields. There has been only one review of electric fields [Moulder and Foster, 1999]. This paper fills this gap by systematically and critically reviewing electric-fields epidemiologic literature and by comparing overall strength of evidence for electric versus magnetic fields. ß 2009Wiley-Liss,Inc. —————— Grant sponsor: Energy Networks Association, UK. *Correspondence to: Leeka Kheifets, UCLA School of Public Health, Department of Epidemiology, 650 Charles E. Young Drive South, Los Angeles, CA 90095-1772. E-mail: kheifets@ucla.edu Received for review 18 October 2008; Final revision received 27 March 2009 DOI 10.1002/bem.20527 Published online 31 July 2009 in Wiley InterScience (www.interscience.wiley.com).