No evidence of oxidative stress in cells exposed to RFR
Cells stressed by oxidation react by producing substances that are called free oxygen radicals or reactive oxygen species (ROS). These may be harmful to the organism. In September of '04 we reported that Zmyslony and colleagues found that ROS levels were increased in rat lymphocytes exposed to radiofrequency radiation (RFR) at 930 MHz (SAR 1.5 W/kg) for either 5 or 15 minutes. Hook et al. (2005), however, report no evidence of oxidative stress in mouse macrophage cells exposed to RFR at either 835.62 MHz (FMCW) or 847.74 MHz (CDMA) at a SAR of 0.8 W/kg for 20-22 hours.
For more, see "Toxicological Experiments - Others - Free oxygen radicals".
Hook GJ, Spitz DR, Sim JE, Higashikubo R, Baty JD, et al. (2005). Evaluation
of parameters of oxidative stress after in vitro exposure to FMCW- and
CDMA- modulated radiofrequency radiation fields. Radiat Res 163:497-504.
On several occasions we have discussed results of studies suggesting that exposure to RFR can lead to increased production of heat shock proteins (hsps) - see "What's New", July '00, November '01, August '02 and November '02, April '03, and October '04. It has been suggested that increased levels of hsps after RFR could indicate that the cells are stressed by the exposure, and that the hsps could induce or promote cancer. Now Lim and colleagues (2005) contribute to the debate. They found no evidence of an increase in hsp27 or 70 levels following exposure to either continuous wave or GSM-modulated RFR at 900 MHz for periods up to 1 hour.
For more, see "Toxicological Experiments - Others - Heat-shock response".
Lim HB, Cook GG, Barker AT, Coulton LA (2005). Effect of 900 MHz electromagnetic
fields on nonthermal induction of heat-shock proteins in human leukocytes.
Radiat Res 163:45-52.
Vijayalaxmi and Obe have published a detailed review of studies that examined the effect of radiofrequency radiation on genotoxicity. They report that 58% did not indicate increased damage to the genetic material, 23% reported an increase in damage, and 19% were inconclusive. The authors attempt to identify reasons for the varying results, and make recommendations for future research.
This subject is reviewed in "Research - Toxicological Experiments - Cancer studies".
Vijayalaxmi, Obe G. Controversial cytogenetic observations in mammalian
somatic cells exposed to radiofrequency radiation. Radiat Res 2005;163:481-96
A new international standard for measurement of mobile phone exposure has been developed jointly by the International Electrotechnical Committee, by the European Committee for Electrotechnical Standardization (CENELEC) and by the Institute of Electrical and Electronics Engineers. The standard specifies methods that can be used to measure SAR limits and brings together different practices and methods used around the world. It will help mobile phone manufacturers, and others making hand-held communication devices, ensure that their devices are in accord with recognized SAR limits.
For more, see www.iec.ch