EXPOSURE ASSESSMENT FOR POWER FREQUENCY ELECTRIC AND MAGNETIC-FIELDS (EMF) AND ITS APPLICATION TO EPIDEMIOLOGIC STUDIES

Epidemiologic studies suggesting possible health effects associated wi th exposure to electric and magnetic fields (EMF) from the transmissio n, distribution, and use of electricity have motivated increased inter est in and attention to EMF exposure assessment. The result has been n ew instruments, measurement approaches, and exposure models that can i mprove on what has been a weakness in past epidemiologic studies, name ly EMF exposure assessment. This paper presents a status report on EMF exposure assessment that emphasizes the need for incorporation of the se advances in future studies. Several factors are identified that mak e the assignment of contemporary or retrospective EMF exposures potent ially more difficult than for other environmental agents. These includ e: EMF is not generally detectable by humans, exposure scenarios for E MF are generally not memorable, there is no clear mechanism for EMF ef fects, and the pervasive nature of EMF in an industrialized society ma kes identification of a low-exposure group difficult. Elements of stud y design that are impacted by the nature of EMF exposures include: sam pling and measurement strategies, summary measures of exposure, and th e choice of surrogate and/or models of exposure. Consideration of thes e exposure assessment issues and incorporation of recent advances can improve the overall quality of epidemiologic studies with an EMF expos ure component.