bias in case-control studies of cell phones and brain tumours
is one of the countries participating in the international case-control
study of cell phone use and brain tumours (INTERPHONE). The authors
of a recent article investigated whether there was any evidence
of selection bias in their
study. In other words, they attempted to determine whether there
was a difference in cell phone use between those who agreed to participate
in the case-control study and those who declined to participate.
They also investigated whether any observed differences had an impact
on the findings with regard to brain tumour risk. They found that
non-participants were less likely to regularly use a cell phone,
and that this tended to move the odds
ratio further below unity, although the effect was not "substantial".
Lahkola A, Salminen T, Auvinen A. Selection bias due to differential
participation in a case-control study of mobile phone use and brain
tumors. Ann Epidemiol 2005;15:321-325.
UTMS-like exposure has no effect on visual
have been a number of studies of the possible effects of cell phones
on brain function, with varying results. Schmid and colleagues recently
investigated the effects of a 1.97 GHz UTMS-like signal on visual
perception, using a battery of four tests. They found no statistically
significant differences between the exposure conditions and
more, see "Research - Clinical
Experiments - Cognitive function".
Schmid G, Sauter C, Stepansky R, Lobentanz IS, et al. No influence
on selected parameters of human visual perception of 1970 MHz UMTS-like
exposure. Bioelectromagnetics 2005;243-250.
Re-evaluation of SAR estimates in heads of
children and adults
has been ongoing controversy about whether the exposure level of
radiofrequency (RF) energy from the use of a cell phone next to
the head is higher for children than for adults. This topic has
been discussed in "What's New"
of September '03, March '04, and April '05. Bit-Babik and colleagues
used a commercial Finite-Difference-Time-Domain (FDTD) numerical
code to compute locally averaged SAR in two different anatomically
correct adult and child head models using the IEEE standard averaging
logarithm. Modeling and experimental measurements were also made
using three spheres filled with a tissue-equivalent mixture, to
approximate heads of increasing size. The peak 1- and 10-g average
SAR values and electromagnetic energy penetration depths were not
significantly different for child and adult heads exposed to the
same RF-energy transmitting device. The authors suggest that the
differences that were reported in other studies might be due to
use of different algorithms for calculating spatial averaged SARs.
They make a plea for standardization of "numerical models,
definitions, positions, procedures an algorithms for SAR calculations".
Bit-Babik G, Guy AW, Chou CK, Faraone A, et al. Simulation of exposure
and SAR estimation for adult and child heads exposed to radiofrequency
energy from portable communication devices. Radiat Res 2005;163:580-590.
Feasibility of epidemiological studies on
health effects of base stations
Swiss agencies sponsored an examination of the feasibility of future
epidemiological studies on health effects or effects on well being
from environmental sources, with particular emphasis on mobile telephone
base stations. The final report of the committee has now been published.
It gives a detailed analysis of dosimetric approaches, epidemiological
issues, past and current research, and requirements for future studies.
Study on the feasibility of epidemiological studies on health effects
of mobile telephone base stations - final report. Neubauer G, Roosli
M, Feychting M, Hamnerius Y, Kheifets L, Kuster N, Ruiz I, Schuz
J, Uberbacher R, Wiart J. March, 2005.