Development of a Source-Exposure Matrix for Occupational Exposure Assessment of Electromagnetic Fields in the INTEROCC Study

摘要

Introduction: As part of the INTEROCC study, we collected information on work with sources of exposure to electric and magnetic fields (EMF) by using a detailed source-based questionnaire, covering the entire EMF frequency range (from 0 Hz to 300 GHz). To estimate occupational exposure of study subjects to the EMF sources identified, we constructed a database of source-based measurements from published and unpublished literature. The aim of the current work was to summarize these measurements into a source-exposure matrix (SEM), accounting for their quality and relevance. Methods: We developed methods for combining available measurements based on the assumptions of log-normality and symmetric quantiles of EMF data. Pooled estimates were weighted by our confidence in the combined measurement data. Arithmetic and geometric means, as well as estimates of variability and maximum exposure were calculated by EMF source, frequency band and dosimetry type. Results: The SEM contains confidence-weighted exposure estimates for the electric (E-field) and magnetic (H- and B-field) fields for 312 EMF exposure sources. Operator position geometric mean electric field levels for RF sources ranged between 0.8 V/m (plasma etcher) and 320 V/m (RF sealer), while magnetic fields ranged from 0.02 A/m (speed radar) to 0.6 A/m (microwave heating). For ELF sources, electric fields ranged between 0.2 V/m (electric forklift) and 11,700 V/m (HVTL-hotsticks), while magnetic fields ranged between 0.14 μT (visual display terminals) and 17 μT (TIG welding). Conclusion: The methodology developed allowed the construction of an EMF-SEM from measurements collected from the literature and may be used to summarize similar exposure data for other physical or chemical agents. The SEM will be used together with detailed information on distance to the source, automation, and other determinants of exposure reported by the study subjects, to calculate indices of cumulative exposure to EMF for their use in the analysis of brain tumours risk associated with these exposures. The SEM will also be offered publicly for its use by other researchers.