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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
2004;162:201-210.
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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