October 2001

Study fails to show DNA damage after RF radiation exposure

There is ongoing controversy about whether or not RF radiation can produce genotoxic effects - for details, see "Research - Toxicological Experiments" on this web site. Li and colleagues report that they could find no evidence of DNA damage in cells that had been exposed to RF radiation at SARs of 3.2-5.1 W/kg. This SAR level is about twice the peak level allowed by the FCC in the United States. The cells were irradiated using 847.74 MHz CDMA and 835.62 MHz FDMA fields for either 2, 4, or 24 hours.

Reference: Li L, Bisht KS, LaGroye I, Zhang P, et al. Measurement of DNA damage in mammalian cells exposed in vitro to radiofrequency fields at SARs of 3-5 W/kg.
Radiation Research 2001;156:328-332.

Regulation of body temperature during RF exposure

Adair and colleagues have shown previously that exposure to RF radiation at a peak surface SAR of 7.7 W/kg did not increase the core body temperature, measured in the oesophagus at the level of the heart. They now report a study in which volunteers were exposed to RF fields that produced a peak surface SAR of 15.4 W/kg and an estimated whole body SAR of 1.0 W/kg. Both these levels are outside the IEEE guidelines. They found no change in oesphageal temperature or metabolic heat production. Local heat increases at skin level were compensated by heat loss responses of increased blood flow and sweating.

Reference: Adair ER, Mylacraine KS, Cobb BL. Human exposure to 2450 MHz CW energy at levels outside the IEEE C95.1 standard does not increase core temperature. Bioelectromagnetics 2001;22:429-439.

NRPB Report on possible health effects from TETRA

Terrestrial Trunked Radio (TETRA) is a new digital system for mobile radio for use by commercial organizations and emergency services. It operates at around 400 MHz. It is being used in the UK and will probably be used widely in the future.

An Advisory Group of the National Radiological Protection Board (NRPB) in the UK has published a report on possible health effects from TETRA. Concern had arisen because the RF signal is pulse modulated at a frequency of 17.6 Hz. The Independent Expert Group on Mobile Phones (IEGMP) suggested last year that as a precautionary measure amplitude modulation at around 16 Hz should be avoided. They did so because some studies had suggested that RF exposure modulated at 16 Hz could increase leakage of calcium from brain and other tissues.

The Advisory Group reviews the issues involved and states that " it is unlikely that the special features of the signals from TETRA mobile terminals and repeaters pose a hazard to health".

Reference: Report on Possible Health Effects from Terrestrial Trunked Radio (TETRA). Report of an Advisory Group on Non-Ionising Radiation. Published on the NRPB web site 31 July 2001 www.nrpb.org.uk

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