Feasibility of a cohort study on health risks caused by occupational exposure to radiofrequency electromagnetic fields

Breckenkamp J, Berg-Beckhoff G, Muenster E, et al. Feasibility of a cohort study on health risks caused by occupational exposure to radiofrequency electromagnetic fields. Environmental Health. 2009;8(1):23.Background: The aim of this study was to examine the feasibility of performing a cohort study on health risks from occupational exposure to radiofrequency electromagnetic fields (RF-EMF) in Germany. Methods: A set of criteria was developed to evaluate the feasibility of such a cohort study. The criteria aimed at conditions of exposure and exposure assessment (level, duration, preferably on an individual basis), the possibility to assemble a cohort and the feasibility of ascertaining various disease endpoints. Results: Twenty occupational settings with workers potentially exposed to RF-EMF and, in addition, a cohort of amateur radio operators were considered. Based on expert ratings, literature reviews and our set of predefined criteria, three of the cohorts were identified as promising for further evaluation: the personnel (technicians) of medium/short wave broadcasting stations, amateur radio operators, and workers on dielectric heat sealers. After further analyses, the cohort of workers on dielectric heat sealers seems not to be feasible due to the small number of exposed workers available and to the difficulty of assessing exposure (exposure depends heavily on the respective working process and mixture of exposures, e.g. plastic vapours), although exposure was highest in this occupational setting. The advantage of the cohort of amateur radio operators was the large number of persons it includes, while the advantage of the cohort of personnel working at broadcasting stations was the quality of retrospective exposure assessment. However, in the cohort of amateur radio operators the exposure assessment was limited, and the cohort of technicians was hampered by the small number of persons working in this profession. Conclusion: The majority of occupational groups exposed to RF-EMF are not practicable for setting up an occupational cohort study due to the small numbers of exposed subjects or due to exposure levels being only marginally higher than those of the general public

Optimal SAR Distribution from Waveguide Applicators for Hyperthermia of Deep-seated Tumours

A major characteristic in hyperthermia technology is the ability to focus heat energy on a small region around the tumour to be treated. By applying Kirchhoff-Huygens principle and the scalar theory of diffraction, specific absorption rate (SAR) distribution in a homogeneous muscle due to arrays of open-ended rectangular waveguide as direct-contact applicators (ORWDAs) at 915 MHz are calculated. The results are compared with that of a single ORWDA operating at the same frequency. The array applicators may offer improvement in field size and penetration depth

Fields due to open-ended waveguide applicators for microwave hyperthermia

This paper demonstrates that in microwave hyperthermia, while a single open-ended rectangular waveguide antenna (ORWA) applicator may be used for the treatment of only the superficial cancerous tumours, an ORWA array may possibly be used for heating of deep-seated tumours. By applying the Kirchhoff-Huygens principle and scalar theory of diffraction, the near-field distributions due to a single ORWA and ORWA arrays in an adjacent homogeneous human muscle are calculated. ORWA array applicators have better performance because of their field focusing effect which depends on the number of element