Abstract:
Electromagnetic field (EMF) radiation became a particular focus for industrial hygiene beginning in the mid 1960's when symptoms such as headache, insomnia, and cardiovascular changes were reported in switchyard workers in the former Soviet Union (WHO, 1989). Before then, hazards associated with the use of electrical power were thought to be limited to thermal burns and electrocution. Over the past 30 years research has been conducted on the potential for adverse health effects resulting from EMF exposure.
Results of the numerous health studies are conflicting. Some epidemiological results report positive associations between EMF and the development of childhood and adult cancers, while others do not. A major criticism of much of the work is the lack of accurate exposure assessments, since a majority of the studies used surrogate measures of exposure such as job titles or wire coding. These methods were used at the time because personal exposure monitors (PEM) were not available until the late 1980's.
Pems measure the magnetic flux density over time, which is typically summarized as a time weighted average (arithmetic mean). This metric and others summarizing central tendency or peak exposures have been traditionally used in EMP exposure assessment. It is not known which of these metrics is the most appropriate summary since there is no universally accepted explanation regarding the action of magnetic fields on living tissue. Alternatively, it has been proposed that temporal measurements summarizing the rate of change and magnitude of magnetic field strength may be more pertinent on adverse cellular interaction (Burch, 1999; Yost, 1999).
This paper presents the results of a project to characterize EMF exposures of ground crew personnel at an airline in the United States using PEMs. Traditional metrics used for EMP exposure are compared to alternative temporal metrics that summarize intermittent changes in the magnetic field. The data also are added to a larger EMF Job Exposure Matrix (JEM) of over 200 occupations similarly characterized using PEMs. It is hoped that this data, along with the remainder of the JEM will provide a more accurate exposure assessment for future studies.