Radiofrequency emissions from video display terminals.
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Biomedical subjects
Publications and source records attributed to M A Stuchly.
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An improved and modified technique with an open-ended coaxial-line sensor was used for measurement of the dielectric properties of animal tissues in vivo. The permittivity of skeletal muscle, brain cortex, spleen and liver of live cats and rats was measured at frequencies between 0.1 and 10 GHz. The results were compared with various published data on in vivo permittivity of the same and other species. The differences between the properties of the same tissue for various animals are very small. The tissues properties at frequencies above 1 GHz correlate well with the water content. Practically all water in the skeletal muscle is in the free form, while in other tissues both free and bound water are present.
Short-wave diathermy is one of the most popular treatment modalities used to relieve pain through localized heating. In Canada its use in hospitals is as frequent as that of ultrasonic therapy devices and about 10 times more popular than microwave diathermy. Intensities of the electric and magnetic fields around applicators of 7 different diathermy units were measured at the operator position and at various untreated areas of the patient during 11 treatment regimes using 5 types of applicators. Exposure to the operator in the normal operating position, behind the device console, usually does not exceed the limits recommended by the Canadian Federal Government. The intense fields around the applicators and the cables extend up to 0.5 m and are a source of potential overexposure to the operator.
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An open-ended coaxial line sensor in conjunction with an automatic network analyzer was used to measure in vivo the permittivity of several feline tissues (skeletal and smooth muscle, liver, kidney, spleen, and brain--gray and white matter) at frequencies between 10 MHz and 1 GHz. The estimated uncertainties of measurement were between 1.5% and 5%. The data are in general agreement with previously obtained data in vitro and in vivo. Significant differences in the properties of different types of the same tissue (eg, skeletal and smooth muscle) were observed. Many tissues were found to be non-homogeneous in its permittivity.
Human health aspects and biological effects of radio frequency (RF) and microwave radiation have been in the focus of research efforts in the last decade. An understanding of the interaction mechanisms between such radiation and living systems is essential in interpreting experimental results and assessing potential health hazards. A comprehensive review of basic biophysical interaction mechanisms between RF and microwaves in the frequency range between 10 MHz and 300 GHz and biological systems is provided in this paper. The interactions at various levels of organization of a living organisms such as molecular, cellular and macroscopic are discussed.
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An increasing proliferation of microwave sources and their continuously broadening scope of applications result in the necessity of an assessment of the potential radiation hazard in various situations. Recently, there has appeared quite a large number of references dealing with specific sources. This paper provides a review of various microwave radiation sources to assist in a general understanding of the basic characteristics of the sources which are pertinent to microwave radiation hazards.
Most wireless phones and their corresponding base stations operate at a very low power output and in the radiofrequency range of 800 to 2000 Megahertz. Current international guidelines protect against thermal biological effects in terms of the local or whole-body specific absorption rate (SAR). Potential non-thermal bio-effects resulting from the use of wireless phones are not established and laboratory (i.e., in vitro, in vivo) studies have shown conflicting results. Epidemiological studies of potential human health effects are few but are expected to emerge in the near future. Challenges to epidemiological research include difficult exposure assessment, selection of appropriate controls, potential confounding bias, and validation of outcome. Scientists, community advocacy groups, and public health professionals must be equipped to critically analyze the emerging evidence within a benefit/risk assessment framework.