A method for assessing occupational exposure to power-frequency magnetic fields for electricity generation and transmission workers

摘要

A new method for assessing both current and historical occupational exposures to magnetic fields has been developed and used in health studies involving a cohort of electricity generation and transmission workers in England and Wales. The exposure values are derived by calculation from engineering and operational data about the power stations rather than from measurement. They are provided for each of 11 job categories for each year of operation of each power station represented in the cohort. The engineering data are used to determine the average magnetic fields in specified areas of work within the power station and then applied to information about the time spent in these areas by each of the job categories. The operational data are used to adjust the exposures for each year according tot he power station output for the year. Earlier methods used measures or the advice of panels of experts to provide exposure scores fro number of job categories across all power stations and years. Such methods were not able to distinguish exposures form different power facilities or during the different years of their operation. Measurement surveys at 10 power stations of the magnetic fields in the work areas give confidence that the calculations were realistic. Exposure measurements on 215 workers at three power stations were compared in job groups with the exposures predicted by the method. The Pearson correlation coefficient was 0.86 μT respectively. The method gives a good prediction of measured exposure and is being used for studies of occupational exposure to magnetic fields and leukemia, and of cardiovascular disease, and a reanalysis of brain cancer.