May 2006

RF exposure and melatonin production

Results of previous studies on melatonin production after RF exposure have been inconsistent. Most have shown no effect. Wood and colleagues exposed 55 volunteers to 895 MHz RFR for 30 minutes. Output of a melatonin metabolite was the same in exposed compared with control subjects in one measure. By another method of measurement the pre-bedtime output of melatonin was decreased in the RFR-exposed subjects. This was entirely due to 4 individuals who had outputs that were extreme "outliers" compared to the others. It was thought that this was due to this small group having delayed onset of melatonin production, or some confounding factor e.g. prior exposure to bright light before coming to the laboratory.

For more, see "Research - Clinical - Hormone secretion".

Reference: Wood AW, Loughran SP, Stough C. Does evening exposure to mobile phone radiation affect subsequent melatonin production? Int J Radiat Biol 2006;82:69-76

Mobile phone related symptoms - no difference in controlled tests

Some people complain of electrical hypersensitivity (EHS) - see "What's New, June '02, April '03, September '05, and April '06". However, when people with EHS have been tested in controlled trials, they have been unable to detect the RF-exposure condition, as opposed to a sham-exposure. Wilen and colleagues carried out a number of physiological measurements and cognitive tests on subjects who complained of symptoms related to mobile phones, but who did not complain of EHS. There were no significant differences related to RF exposure between cases and controls. There was increased heart rate variability in the cases during a critical flicker fusion threshold test and a memory test.
The authors considered that this might be due to differences in the autonomic nervous system regulation between persons with MP related subjective symptoms and persons with no such symptoms.

For more, see "Research - Clinical - Others- General Health effects, including electromagnetic field hypersensitivity", and FAQ #13.

Reference: Wilen J, Johansson A, Kalezic N, Lyskov E, et al. Psychological tests and provocation of subjects with mobile phone related symptoms. Bioelectromagnetics 2006;27:204-214.

Study on effect of RF exposure on function of the immune system

There have been few studies of the effect of RF exposure on immune function. Tuschl and colleagues tested the effect of short-term exposure from a GSM Basic signal on human lymphocytes and monocytes. They found no evidence that the RF exposure had any effect on the numerous tests of immune function that they performed.

For more, see “Research – Toxicological – Others -Immune system”.

Reference: Tuschl H, Novak W, Molla-Djafari H. In vitro effects of GSM modulated radiofrequency fields on human immune cells. Bioelectromagnetics 2006;27:188-196.

No effect of RFR on cell death

Merola and colleagues did experiments on a neuroblastoma cell line. This is a solid tumour, mainly found in children. They exposed the cells to RFR from a 900 MHz signal for up to 72 hours. They found no alterations in cell death, proliferation, or differentiation in the exposed cells, when compared with sham-exposed cells.

For more, see "Research - Toxicological - Others - Cell death".

Reference: Merola P, Marino C, Lovisolo GA, Pinto R, et al. Proliferation and apoptosis in a neuroblastoma cell line exposed to 900 MHz modulated radiofrequency field. . Bioelectromagnetics 2006;27:164-171.

More analyses from Hardell's group

Another publication has emerged from Hardell and colleagues in Sweden. This one reported the combined results from two case-control studies on the use of cell and cordless phones and the risk for malignant tumour. The studies covered the period 1997-2003. They found increased risks for analogue, digital, and cordless phones, particularly for those who had cumulative use of >2,000 hours, and for those with > 10 years use. Multivariate analyses reduced the risk assessments.

The results from this group are consistently different from those of others who have studied this problem. The reasons for this are debated in epidemiological circles. For more, see "Research - Epidemiology".

Reference: Hardell L, Carlberg M, Mild KH. Pooled analyses of two case-control studies on use of cellular and cordless telephones and the risk for malignant brain tumours diagnosed in 1997-2003. Int Arch Occup Environ Health 2006;published on-line March 16.