Noviembre 2004

Another study fails to confirm Lai's findings

In 1994 Lai, Horita and Guy published a paper that had a significant impact on the debate about whether radiofrequency radiation (RFR) in the cell phone range had the potential for adverse health effects. They reported that, after 45 minutes exposure to 2450 MHz microwaves, rats showed retarded learning while performing in a radial-arm maze to obtain food rewards. They claimed that this showed a deficit in spatial "working memory" function. Cobb et al. (2004) carried out a replication study and failed to confirm the findings of Lai et al. (see "What's New", February 2004). Now Cassel and colleagues have also performed a study to attempt to replicate Lai's study. Like the Cobb study, they were unable to show any difference in the behaviour of the exposed rats, compared with a sham-exposed or another control group.

For more, see "Research - Toxicological Experiments - Brain function".

Reference: Cassel JC, Cosquer B, Galani R, Kuster N. Whole-body exposure to 2.45 GHz
electromagnetic fields does not alter radial-maze performance in rats. Behav
Brain Res 2004;155:37-43.

Another epidemiological review

There have been a series of reviews of epidemiological studies of the relationship between cell phones and cancer. Most have concluded that there is no convincing evidence to date of any association. A recent review by Kundi and colleagues comes to a somewhat different conclusion. While agreeing with others that all studies have some methodological deficiencies, they go on to state:

"Nevertheless, all studies approaching reasonable latency found an increased cancer risk associated with mobile phone use".

One of the authors, Dr Hardell, has been the principal author of a number of epidemiological studies. For more, see "Research - Epidemiology".

Reference: Kundi M, Mild K, Hardell L, Mattson M-O. Mobile telephones and cancer - a
review of epidemiological evidence. Journal of Toxicology and Environmental
Health Part B 2004;7:351-384.

No effect of long-term RFR exposure on cancer incidence in rats

There have been a number of animal studies that have examined the effect of radiofrequency radiation on cancer incidence. The majority has shown no effect. Another study has been published that adds to the body of evidence that long-term RFR exposure, at cell phone frequency and SAR exposure level, has no effect on cancer incidence in animals. Anderson and colleagues exposed rats for 2 years to a 1600 MHz RF field and could find no difference in exposed versus sham-exposed groups in survival or cancer incidence. For more, see "Research - Toxicological Experiments - Cancer".

Reference: Anderson LE, Sheen DM, Wilson BW, Grumbein SL, et al. Two-year chronic bioassay study of rats exposed to a 1.6 GHz radiofrequency signal. Radiation Research

Suggestions for exposure design in human studies of cell phones

There are considerable challenges in conducting studies of cell phones in human volunteers. Kuster and colleagues have published guidelines to help standardize exposure assessment in such studies. They cover such areas as exposure distribution and strength, design of the exposure set-up, signal characteristics, dosimetry, and characterization of unwanted influences.

Reference: Kuster N, Schuderer J, Christ A, Futter P, et al. Guidance for exposure
design of human studies addressing health risk evaluations of mobile phones.
Bioelectromagnetics 2004 25:524-529.

An examination of the effect of modulation

There has been much speculation about the biological importance of modulation of radiofrequency (RF) energy. Foster and Repacholi have reviewed this issue in a recent publication. They examine in particular the reports of modulation-dependent effects of RF energy on calcium efflux from brain tissue. The mechanisms underlying such an effect, if it exists, are not understood. The authors make a plea for further research in this area to confirm or refute the findings of previous studies, but also state that other aspects of good study design may be more important in future research on effects of RF energy.

Reference: Foster KR, Repacholi MH. Biological effects of radiofrequency fields: Does
modulation matter? Radiation Research 2004;162:219-225.

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