March 2006

Australian survey of RF exposure from base stations

A survey of the radiofrequency electromagnetic energy from 60 base stations in Australia has shown that exposure levels are well below the general public exposure limits of the ICNIRP guidelines. The highest recorded level was 0.2% of the general public exposure limit.

Reference: Henderson SI, Bangay MJ. Survey of RF exposure levels from mobile telephone base stations in Australia. Bioelectromagnetics 2006;27:73-76.

Personal dosimetry of exposure to base stations

The measurement of exposure to RFR from base stations is one of the challenges of epidemiological studies of health effects from this exposure. Radon and colleagues tested two personal dosimeters and found only moderate agreement between them, and no correlation with self-reported exposures.

Reference: Radon K, Spegel H, Meyer N, Klein J, et al. Personal dosimetry of exposure to mobile telephone base stations? An epidemiologic feasibility study comparing the Maschek dosimeter prototype and the Antenessa DSP-090 system. Bioelectromagnetics 2006;27:77-81.

See "Base stations" and “Research – Epidemiology” for more on the challenges of exposure assessment in epidemiologic studies.

There have also been three recent articles on heat-shock protein response after RFR exposure.

Thermal cause of heat-shock response to RFR called in to question

De Pomerai and colleagues for some time have been conducting experiments on the effect of radiofrequency radiation (RFR) on the C. elegans worm. In 1998 and 2000 (see “What’s New” July 2000) they reported that low-intensity RFR could elicit a clear heat-shock response that was apparently non-thermal in nature. They have now published the results of new experiments using a modified TEM cell that reduces power loss and consequent heating. In these new conditions there was no difference between exposed worms and sham controls in their response. They further showed that the small temperature rise that was evidently present in their earlier experiments is enough to produce a significant heat-shock response. The authors state:

 

“We conclude that our original interpretation of a non-thermal effect of microwaves cannot be sustained; at least part of the explanation appears to be thermal”.
The authors have submitted a retraction to the journal Nature regarding their 2000 paper.

For more, see “Toxicological experiments – Others – Heat-shock response”.

Reference: Dawe AS, Smith B, Thomas DWP, Greedy S, et al. A small temperature rise may contribute towards the apparent induction of heat-shock gene expression in the nematode Caenorhabditis Elegans. Bioelectromagnetics 2006;27:88-97.

No hsp70 response after RFR exposure at 1800 MHz

In this study two types of cells from human leukaemia lines were exposed to RFR and other conditions. No significant effects on hsp expression were seen after exposure to RFR at 1800 MHz at SARs of 0.5-2.0 W/kg for 45 minutes.

The authors also found no effect on free radical production after RFR exposure.

For more, see “Toxicological experiments – Others – Heat-shock response, and Free Oxygen Radicals”.

Reference: Lantow M, Schuderer J, Hartwig C, Simko M. Free radical release and HSP70 expression on two human immune-relevant cell lines after exposure to 1800 MHz radiofrequency radiation. Radiation Research 2006;165:88-94


No adverse effects of RFR exposure in hsp-deficient or wild mice

Lee and colleagues have generated mice deficient in hsp70.1in their laboratory. In this study they conducted a bioassay of the hsp70.1-deficient mice after a prolonged exposure to RFR to see if these mice are vulnerable to this situation. RFR exposure did not result in any evidence of changes in cell proliferation, apoptosis, or stress response. Wild mice likewise showed no evidence of changes in these parameters.

For more, see “Toxicologicall experiments – Others – Heat-shock response”.

Reference: Lee J-S, Huang J-J, Lee J-J, Pack J-K, et al. (2005): Subchronic exposure of hsp 70.1-deficient mice to radiofrequency radiation. Int J Radiat Biol 81:781- 792.

Study on cognitive function and RFR exposure

Several studies of the effect of RFR exposure on cognitive function have been done, with varying results. Some have reported a decrease in reaction times, although the results in at least one study have failed to be replicated. Other studies have shown no effect. A new study has reported a slowing of response time in certain situations in a series of tests, although the slowed response reached statistical significance in only one test. For more, see “Research-Clinical Experiments-Cognitive function”.

Reference: Eliyahu I, Luria R, Hareuveny R, Margaliot M, et al. Effects of radiofrequency radiation emitted by cellular telephones on the cognitive function of humans. Bioelectromagnetics 2006;27:119-126.

Another study fails to show tumour promotion in rats exposed to RFR

Dimethylbenz(a)anthracene (DMBA) is known to promote the development of mammary tumours in rats. Several studies have failed to show any additional tumour development in rats given DMBA and then exposed to RFR. In another recent study of rats exposed for 4 h/day, 5 days a week, for 26 weeks to 900 MHz RFR, a similar result was seen. There were no significant differences between RFR-exposed and sham-exposed animals in tumour development, latency, or size.

For more, see “Research- Toxicological– cancer studies – tumour growth and development”.

Reference: Yu D, Shen Y, Kuster N, Fu Y, et al. Effects of 900 MHz GSM wireless communication signals on DMBA-induced mammary tumors in rats. Radiation Research 2006;165:174-180.

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