January 2007

Cohort study of cell phone use and cancer risk

Johansen et al. (2002) reported on a cohort study of cell phone users and cancer risk. This group has now updated their findings. They followed 420,095 subscribers and linked them to the Danish Cancer Registry. The mean time of cell phone use was 8.3 years, with a maximum of 21 years. They found no evidence of an association between tumour risk and cell phone use.

For more, see Research – Epidemiology”.

Reference: Schuz J, Jacobsen R, Olsen JH, Boice JD Jr., et al. (2006d): Cellular telephone use and cancer risk: Update of a nationwide Danish cohort. J Natl Cancer Inst 98:1707-1713.

Another negative study of RFR and the stress response

Lee and colleagues have added to the growing number of studies that have shown no effect of RFR exposure on the induction of indicators of stress responses in the cell. They exposed cells to RFR at SAR of either 2 or 20 W/kg for 30 minutes or 1 hour, and found no change in expression of heat shock proteins or other activators of stress responses.

For more, see “Research – Toxicology – Others – Heat shock response”.

Reference: Lee J-S, Huang T-Q, Kim T-H, Kim JY, et al. Radiofrequency radiation does not induce stress response in human T-lymphocytes and rat primary astrocytes. Bioelectromagnetics 2006;27:578-588.

New method proposed for estimating exposure levels for cell phone users

One of the most difficult tasks in conducting an epidemiological study of the risks of cell phone usage is to accurately assess exposure levels of users.

SC Kim and colleagues have proposed a new method to estimate quantitative and relative RF exposure levels using a neural network model. The parameters that were used to develop this model were average usage time per day, total period of usage in years, SAR of the specific phone, hands-free usage, antenna extraction, and the type of phone (flip or folder). They used these because they believe them to be related to RF exposure. The authors emphasize that their method needs to be developed and updated as future research enables RF exposure to be more accurately estimated.

Reference: Kim SC, Nam KC, Kim DW (2006): Estimation of relative exposure levels for cellular telephone users using a neural network. Bioelectromagnetics 27:440-444.

RFR exposure and the skin

There have been few papers that have examined the effect of RFR exposure on the skin.
Two papers, authored by the same group of researchers, have now reported the effect of RFR exposure on the skin (Manchez 2006, Sanchez 2006). Skinless rats were exposed to either 900 or 1800 MHz RFR, either for 2 hours at SAR of 5 W/kg, or for 2 hours per day, 5 days a week, for 12 weeks at 900 or 1800 MHz at SAR of 2.5 or 5 W/kg. There were no significant changes in the skin of exposed rats, when compared with skin from an unexposed part of the same area of the rat, or of control or sham-exposed rats.

For more, see “Research – Toxicology– Others – Skin”.

References: Masuda H, Sanchez S, Dulou PE, Haro E, et al. Effect of GSM-900 and -1800 signals on the skin of hairless rats: 1: 2-hour acute exposures. Int J Radiat Biol 2006;82:669-674.

Sanchez S, Masuda H, Billaudel B, Haro E, et al. Effect of GSM-900 and -800 signals on the skin of hairless rats: 11: 12-week chronic exposures. Int J Radiat Biol 2006;82:675-680.

Anesthesia affects temperature in rabbits' eyes

There have been varied results in experiments testing the effect of RFR on rabbits' eyes. Kojima et al. reported that anesthesia affects the thermoregulatory control mechanisms, and leads to increased temperatures in the eyes of the rabbits (see "What's New" June "04). The same group has now confirmed this finding, and has also shown that a computational model gives results that are in good agreement with results seen in live animals.

For more, see "Research - Toxicology - Ocular".

Reference: Hirata A, Watanabe S, Kojima M, Hata I, et al. Computational verification of anesthesia effect on temperature variations in rabbit eyes exposed to 2.45 GHz microwave energy. Bioelectromagnetics 2006;27:602-612.

Review of the effect of ELF-modulated RF fields on brain function

Cook and colleagues have updated a 2002 review of brain electrophysiological and cognitive responses to EMF exposure. Some of the review relates to ELF-modulated RF fields. They report that there are more reports of physiological effects than performance effects, and offer possible explanations for these observations.

For more, see “Research – Clinical – EEG and Cognitive function”.

Cook CM, Saucier DM, Thomas AW, Prato FS. Exposure to ELF and ELF-modulated radiofrequency fields: The time course of physiological and cognitive effects observed in recent studies (2001-2005). Bioelectromagnetics 2006;27:613-627.

No effect of RFR on ROS or HSP70 levels

Another paper has failed to show any effect of RFR on reactive oxygen species (ROS) or HSP70 levels. Human lymphocytes and monocytes were exposed to 1800 MHz RFR for 30 or 45 minutes at 2W/kg SAR for the ROS investigation, or for 1 hour for the HSP study. No increase was seen in ROS induction or HSP&) levels.

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

Lantow M, Lupke M, Frahm J, Mattson MO, et al. ROS release and Hsp70 expression after exposure to 1,800 MHz radiofrequency electromagnetic fields in primary human monocytes and lymphocytes. Radiat Environ Biophys 2006;45:55-62.