Future needs of occupational epidemiology of extremely low frequency electric and magnetic fields: review and recommendations
- L Kheifets1,
- J D Bowman2,
- H Checkoway3,
- M Feychting4,
- J M Harrington5,
- R Kavet6,
- G Marsh7,
- G Mezei6,
- D C Renew8,
- E van Wijngaarden9
- 1Department of Epidemiology, UCLA School of Public Health, Los Angeles, California, USA
- 2National Institute for Occupational Safety and Health, Engineering and Physical Hazards Branch, Cincinnati, Ohio, USA
- 3Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, USA
- 4Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
- 5Institute of Occupational Health, University of Birmingham, Birmingham, UK
- 6Electric Power Research Institute, Palo Alto, California, USA
- 7Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- 8National Grid plc, London, UK
- 9Division of Epidemiology, Department of Community and Preventive Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
- Leeka Kheifets, UCLA School of Public Health, Department of Epidemiology, 73-284 CHS, 650 Charles E Young Drive South, Los Angeles, CA 90095-1772, USA; kheifets{at}ucla.edu
- Accepted 30 July 2008
- Published Online First 19 September 2008
Abstract
The occupational epidemiological literature on extremely low frequency electric and magnetic fields (EMF) and health encompasses a large number of studies of varying design and quality that have addressed many health outcomes, including various cancers, cardiovascular disease, depression and suicide, and neurodegenerative diseases, such as Alzheimer disease and amyotrophic lateral sclerosis (ALS). At a 2006 workshop we reviewed studies of occupational EMF exposure with an emphasis on methodological weaknesses, and proposed analytical ways to address some of these. We also developed research priorities that we hope will address remaining uncertainties. Broadly speaking, extensive epidemiological research conducted during the past 20 years on occupational EMF exposure does not indicate strong or consistent associations with cancer or any other health outcomes. Inconsistent results for many of the outcomes may be attributable to numerous shortcomings in the studies, most notably in exposure assessment. There is, however, no obvious correlation between exposure assessment quality and observed associations. Nevertheless, for future research, the highest priorities emerge in both the areas of exposure assessment and investigation of ALS. To better assess exposure, we call for the development of a more complete job-exposure matrix that combines job title, work environment and task, and an index of exposure to electric fields, magnetic fields, spark discharge, contact current, and other chemical and physical agents. For ALS, we propose an international collaborative study capable of illuminating a reported association with electrical occupations by disentangling the potential roles of electric shocks, magnetic fields and bias. Such a study will potentially lead to evidence-based measures to protect public health.
Footnotes
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Competing interests: This paper is based in part on deliberations at a workshop sponsored by ENA, a UK trade association. L Kheifets and JM Harrington organised and chaired the workshop, with other co-authors as participants. R Kavet and G Mezei are employed by the Electric Power Research Institute; DC Renew is employed by National Grid plc and worked on this paper with the company’s permission.
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Disclaimers: The findings and conclusions in this paper have not been formally disseminated by the U.S. National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy. The views expressed in this paper are those of the authors and not necessarily those of National Grid.
