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