NEW YORK, July 5, 2011 /PRNewswire/ --
The world-renowned International Journal of Hyperthermia has unveiled a new special issue which addresses the thermal aspects of radiofrequency exposure on human health. This special issue resulted from a workshop born out of the controversies surrounding huge growth and use of wireless communication.
In the issue, invited experts further refine a quantitative assessment of the effects of thermal energy on tissue damage, fetal development, immune function and neurocognitive behaviour. The special issue papers are available on: http://informahealthcare.com/toc/hth/27/4.
One of the key findings of the workshop and research papers is that while radiofrequency exposure standards can surely be refined further, it is fair to say that the present exposure limits set for the general public are far more protective against thermal hazards than recommended limits for the temperature of hot water in the home.
"The purpose of the workshop - and the resulting special issue - was to review current knowledge of the effects of heat on the body that are of potential relevance to setting limits for human exposure to radiofrequency," explains the lead review author, Kenneth R Foster, of the Department of Bioengineering at the University of Pennsylvania. "Thermal damage to the body is clearly a very large topic; our discussion and this special issue focuses on thermal effects that are likely to be relevant to setting radiofrequency exposure limits."
"We examined the most appropriate health endpoints for a given tissue or system, appropriate time periods for acute and chronic exposure, time-temperature thresholds for adverse effects, as well as cost effective and targeted research to help us better understand and define human exposure standards," continued Foster.
"The upshot was that current radiofrequency limits, as recommended by the WHO and adopted by the majority of the world's governments, are - in thermal terms - far below temperatures that could harm the body," says Foster. "Indeed, under ordinary environmental conditions, exposure at the whole body limits for the general public, will lead to no detectable increase in core body temperature due to thermoregulatory responses.
That said, both sets of current guidelines on exposure to radiofrequency are subject to limitations, despite the fact that they form the basis for exposure guidelines throughout most of the world. The IEEE (Institute of Electrical and Electronics Engineers) and the ICNIRP (International Commission on Non-Ionizing Radiation Protection) limits set out basic restrictions in terms of power absorbed in tissue. However, the biologically significant quantity is the thermal exposure (increase in temperature and duration of exposure to elevated temperature).
Within the human body, time-temperature functions for thermal damage to different tissue types varies widely and current limit definitions are complex and difficult to explain to the public. In addition, new technologies employing high-power mm wave sources are coming into use and the possibility of human exposure to such energy at potentially injurious levels is increasing.
"If the limiting hazards of RF energy are indeed thermal, several questions must be addressed," says Mark Dewhirst, Professor of Radiation Oncology, Pathology and Biomedical Engineering at Duke University. "Are current limits adequate to protect diverse tissues from thermal injury? Would it make sense to move to a time-temperature based limit? Are present standards adequately protective for exposures to the types of energy employed by modern electronic devices?"
"The workshop and resulting special issue of the International Journal of Hyperthermia addresses these questions and sets out areas where further research is recommended.
The introductory review article for this special issue of the International Journal of Hyperthermia is available on open access at: http://www.informahealthcare.com/hth
|SOURCE International Journal of Hyperthermia|
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