Junio 2007

No cancer-producing effect of RFR exposure in mice
           
Tillmann and colleagues have reported a study performed under the PERFORM-A research program. The aim of this study was to assess potential carcinogenic effects on mice of exposure to RFR from GSM (902MHz) and DCS (1747 MHz) handsets at whole-body SAR levels up to 4 W/kg for 2 hours per day, 5 days per week, for 2 years. The study did not provide any evidence of RF possessing a carcinogenic potential.

For more, see "Research - Laboratory - Cancer studies - Tumour Growth and Development".

Reference: Tillmann T, Ernst H, Ebert S, Kuster N, et al. (2007): Carcinogenicity study of GSM and DCS wireless communication signals in B6C3F1 mice. Bioelectromagnetics 28:173-187.
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Long-term use of cell phones and risk of brain cancer

Three recent papers have reviewed studies that have reported analyses of the risk of brain cancer in those who have used cell phones for at least 10 years. As reported in "What's New" last month Hardell and colleagues examined two cohort and sixteen case-control studies. Eight of the studies gave results on acoustic neuroma. Only four gave results for ≥ 10 years of use, and one of these had only 2 cases. The other 3 gave statistically significant results for ipsilateral use. Nine studies reported on glioma, of which seven gave results for ≥ 10 years of use. Two, including one study by Hardell et al., showed statistically significant results for at least one analysis. Some of the results of their study that are quoted in this paper are not quoted in their original paper.

Lin briefly reviews some of these papers, and comments: “Thus, while the risk of brain tumours from cell phone exposures will likely remain controversial for some time, the latest report opens the door a little wider on the possibility that cell phone use could lead to brain tumours in humans”.

Another recent paper, by Lahkola and colleagues, reported a meta-analysis of cell phone use and intracranial tumours, and the authors concluded:
            "The totality of evidence does not indicate a substantially increased risk of intracranial tumors from mobile phone use for a period of at least 10 years".

References: Hardell LO, Carlberg M, Söderquist F, Hansson Mild K, et al. (2007): Long-term use of cellular phones and brain tumours - increased risk associated with use for > 10 years. Occup Environ Med published online 4 Apr 2007, doi:10.1136/oem.2006.029751
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Lin JC (2007): Mobile phone use and malignant central nervous system tumours. Radio Science Bulletin 320:48-49.
(This paper can be found in pdf format at www.ursi.org )

Lahkola A, Tokola K, Auvinen A (2006): Meta-analysis of mobile phone use and intracranial tumours. Scand J Work Environ Health 32:171-177.

For more on the Epidemiology of cell phone use and intracranial tumours, see “Research – Epidemiology – cell phone studies”.


RFR exposure and skin temperature

A recent study examined changes in temperature in the rabbit ear on exposure to radiofrequency radiation (RFR) for 20 minutes. The ears were exposed for 20 minutes at different SARs. Two experimental conditions were employed - normal blood flow and without blood flow in the ear. It was found that physiological blood flow significantly suppressed temperature rises even at 34.3 W/kg. The authors comment that the effect of blood flow should be taken into consideration when extrapolating modeling studies to living animals.

For more, see "Research - Laboratory studies - Others - Skin".

Reference: Jia F, Ushiyama A, Masuda H, Lawlor GF, et al. (2007): Role of blood flow on RF exposure induced skin temperature elevations in rabbit ears. Bioelectromagnetics 28:163-172.
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RFR exposure and brain function

Several papers have explored this relationship recently, with different results:

1) No effects on brain function from short- and long-term RFR exposure

Fritzer and colleagues assessed brain function in 10 young males exposed to 900 MHz RFR for 6 nights, and 10 controls.  There were no significant effects on sleep parameters or on neuropsychological testing in the exposed subjects, as compared to the controls.

This appears to be the first study on brain function that investigated "long-term" effects.
           
Reference: Fritzer G, Goder R, Friege L, Wachter J et al. (2007): Effects of short- and long-term pulsed radiofrequency electromagnetic fields on night sleep and cognitive functions in healthy subjects. Biolectromagnetics 28:316-325.
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2) Pulse-modulated RFR affects brain function

Regel and colleagues exposed healthy young males for 30 minutes at 900 MHz, over the left hemisphere. The subjects performed 3 tests of cognitive function during exposure, and an EEG was recorded for 6 minutes at 0, 30, and 60 minutes after exposure.

The authors found reduced reaction speed and increased accuracy in a working-memory task done during exposure. The EEG was also affected in the PM exposure, but only at 30 minutes. There were no effects from the CW exposure.

Reference: Regel S, Gottselig, J, Schuderr, J, Tinguely, G, et al. (2007): Pulsed radio frequency radiation affects cognitive performance and the waking electroencephalogram. Neuroreport 18:803-807.
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3) No effects on cognitive function from RFR exposure, to either hemisphere

Haarala et al. in this paper continue the series of studies they have reported on the effects of RFR on cognitive function (Koivisto 2000a,b; Haarala 2003,2004, 2005). They employed the same cognitive tasks that they used in the other studies. Healthy young males were exposed to a 902 MHz electromagnetic field (CW, PM, or sham) at weekly intervals. The exposure was done over each hemisphere in turn. The subjects performed a series of cognitive function tasks during the exposure. The tasks were performed twice during each session, with the laterality of exposure being changed for the second set of tasks.

No effects were found between the different RFR exposure conditions, or separate hemisphere exposures.

The authors provide a useful summary of potential explanations for the varied results that have been found in studies of the effects of RFR exposure on cognitive function.

Reference: Haarala C, Takio F, Rintee T, Lainie M, et al. (2007): Pulsed and continuous wave mobile phone exposure over left versus right hemisphere: Effects on human cognitive function.  Biolectromagnetics 28: 289-295.
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4) No effects on cognitive function, inconsistent effects on EEG from RFR

Haarala is also an author in this paper, and the design of the study was very similar to that of the above. Healthy young males were exposed to a 902 MHz electromagnetic field (CW, PM, or sham) at weekly intervals, while performing either an auditory or a visual memory task. RFR exposure had no effect on cognitive function. Some subtle effects were seen on EEG tracing. These were inconsistent, and were even seen on sham exposure.

Reference: Krause CM, Pesonen M, Bjornberg C Haarala, Hamalainen H (2007): Effects of pulsed and continuous wave 902 MHz mobile phone exposure on brain oscillatory activity during cognitive processing. Bioelectromagnetics 28:296-308.
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For more on these studies, see "Research - Clinical - EEG".



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