After reading enough material on
the possible risk of cell phone usage it is welcome to have an expert view
regarding the actual energetics of DNA damage as a precursor to cancer. It becomes clear that particular route is a
dead end. What this means is that in
terms of the physics we know and believe we understand, there is no route to
cancer.
This does not mean that other
effects are not taking place. Other work
has identified clumping of blood cells, although such clumping been a precursor
to tumor generation appears very unlikely.
Yet something happened that could induce plausibly a cascade of chemical
activity we have not identified.
Unfortunately this is a round about route and is simply not convincing.
On top of that, the statistical evidence
is effectively a comforting zero plus or minus whatever. In short, it appears we can all go back to
sleep. So maybe we can all afford to
wait for a much better demonstration of cause and effect than has been tossed
about or to be more correct gone unmentioned as it does not really exist.
Cell Phone Radiation, Cancer, and The WHO
by John G. Cramer
Alternate View Column AV-160
Published in the October-2011 issue of Analog Science Fiction & Fact Magazine;
This column was written and submitted 2/25/2011 and is copyrighted ©2011 by John G. Cramer.
All rights reserved. No part may be reproduced in any form without the explicit permission of the author.
On May 31, 2011, screaming headlines in many news media were along the
lines of the New York Times story “Cellphone Radiation May Cause Cancer,
Advisory Panel Says”. On that date the World Health Organization
(WHO) announced that a team of 31 scientists, from 14 countries including the USA
As a physicist, I am very troubled by the WHO proclamation and by the
panicky reactions it produced. Nowhere did I find any indication
that a key question had been asked: Is there ANY plausible physical mechanism
by which the electromagnetic microwave radiation from cell phones can possibly
produce DNA damage leading to brain cancer? Answer: There is
not. It seems to me that before we expend huge research resources to
undertake these expensive and inconclusive epidemiological studies, we should
be obligated to ask if the hypothetical effect under study is consistent with
the laws of physics. In other words, does the hypothetical link
between microwaves and cancer that is being investigated makes any sense at
all?
Let me elaborate. In order to produce cancer, the microwave
radiation would have to cause a break or rearrangement of cellular DNA,
modifying the genetic code so that nerve cells in the brain become
cancerous. The microwave photons must produce mutations. Is
that physically possible?
DNA is a rather robust long-chain molecule. It has been
suggested (See my column AV-35 in the October-1989
issue of Analog) that DNA, because it is such a stable and rigid molecule,
could be used for structural engineering at the nanoscale, constructing 3D
mechanical scaffolding made from DNA chains. As structural material DNA offers
several very interesting advantages: the chains are relatively rigid, can be
made in the laboratory to designer specifications, and will link, lock-and-key
fashion, only to complementary sequence of bases of another DNA chain. Thus,
“tinker-toy” DNA scaffolding at the nanoscale could be constructed, a framework
on which nanomachines could be assembled.
A key element of this nano-engineering concept is that it requires a
considerable energy, around 10-20 electron-volts, to break a DNA bond. This
is several times larger than the energy available from typical chemical
reactions or from the energy content of photons of visible light. The
DNA bond strength has been verified experimentally using the cantilever
nano-manipulation of an atomic force microscope. A DNA strand is
stretched like a spring until it reaches its breaking point and snaps. This
only occurs when it has been given about 265 electron volts of stored energy by
the cantilever system, implying a bond strength about 1/10 of that value. DNA
is a tough molecule.
The classical physics of Maxwell’s equations in the 19th century
described light and radio waves as perpendicular electric and magnetic fields
forming traveling waves moving through space at the speed of light with some
wave amplitude and frequency. The energy of the wave was
proportional to the square of the electric field. This picture led
to the conclusion that wave energy and wave intensity were locked together, the
more intense the light (or cell phone waves) the more their energy content, and
the more readily they might break a chemical bond. This antique view
still seems to be embraced by the segments of the medical profession engaged in
epidemiology. However, the dawning of the 20th century brought
a new experimental result, the photoelectric effect, which demonstrated that
the energy delivered by light was correlated with frequency, not
intensity. Albert Einstein, who won the Nobel Prize in 1921 for this
work, showed that the energy content of light was quantized into individual
photons, each of which carried an energy content E = hf, in other words,
Planck’s constant h (4.14 x 10-15 electron volts per Hz)
multiplied by the frequency f of the radiation. Interactions
between light and electrons, like those forming chemical bonds, happen one
photon at a time, and each photon can deliver only an energy of hf.
How, then, could microwave radiation break a DNA bond to produce a
carcinogenic mutation? As we sometimes say in physics, it would
require a visit from the Tooth Fairy. What is the difference between
the energy needed to break a DNA chemical bond and the energy that might be
supplied by the absorption of a photon of microwave radiation? The
most energetic photons of cell phone microwaves are those of the 4G networks
now replacing the older cell network infrastructure, and the 4G system operates
in the frequency range 2.496 to 2.690 GHz (1 GHz = 1 billion cycles per
second). The corresponding energy content of 4G microwave photons is
0.00000103 to 0.00000111 electron volts. This means that the
mismatch between the energy carried by a cell phone microwave photon and the
energy required to damage a DNA molecule is a factor of about one million.
It might be argued that it is possible for coherent microwave radiation
interacting with DNA to produce multi-photon events in which the energy of many
photons is absorbed in a particular quantum event. Such “pile-up”
quantum events do indeed happen with reduced probability, but usually involve
only two or three photons. One would need a million-photon pileup to
supply the needed energy for DNA breaking. The probability of such a
million-photon pile-up event is infinitesimally close to zero, which is physics
terminology for saying “No way!”.
So what does produce DNA mutations? There are two main
culprits: carcinogenic chemicals, and natural radioactivity and ionizing
radiation. Cell division involves replication of DNA and is a
complex chemical process. Alteration of the chemical environment in
which the process takes place can result in copying errors during DNA
reproduction, and this is the most likely cause of mutations. The cell is
also surrounded by a radioactive environment. In particular, some of
the carbon atoms in the DNA itself are the radioactive isotope carbon-14, which
decays by beta emission into nitrogen-14. Every second about 50 carbon
atoms in the DNA of the average human are converted into nitrogen, directly
producing mutations. Fortunately, the cells contain DNA repair
enzymes that compare one side of the double helix with the other and repair
such single-error damage.
Of course, the cell phone microwaves do interact with the brain. After
penetrating the skull with reduced intensity, their energy content will
generate tiny atomic and molecular vibrations that will show up as heat,
slightly elevating the temperature of the head in the region near the cell
phone. The body has a strong interest in maintaining the brain in a
narrow temperature range, so such external heating will stimulate additional
cooling blood flow in the heated region. Recent MRI studies
reporting an increase in brain activity related to cell phone use may reflect
this phenomenon. But it has nothing to do with cancer.
So why do epidemiologist persist in attempting to link cancer to cell
phone use? I think that the answer is: “Because they can.” And
because one inconclusive epidemiological study provides a reason for proposing
and undertaking an even larger and more expensive epidemiological study. There
is no obvious end to such a process.
I think part of the reason is also the confusion at many levels over
the use of the word “radiation”. To the general public, radiation is
a scary word associated with nuclear accidents and cancer. To a
physicist, electromagnetic radiation simply means the traveling waves made of
coupled electric and magnetic fields that are produced mainly by the
acceleration of electric charges. Electromagnetic radiation may be
of any frequency, with examples ranging from the 1 Hz ultra low frequency radio
waves made by lightning strikes to the 70 million electron volt gamma rays,
which have frequencies of about 3.3 x 1022 Hz and are made when neutral pi
mesons decay. All of these are forms of electromagnetic
radiation. The question that should be of interest is whether or not
it is ionizing radiation, i.e., radiation that has a photon energy
large enough to knock an electron loose from an atom. This occurs
when the photon has an energy of around 10 electron volts or more,
corresponding to ultraviolet light and above. Cell phone microwaves
have frequencies a million times too small to constitute ionizing radiation.
However, some might argue that the link between cell phone microwaves
and brain cancer is not a theoretical physic question; it is an experimental
question that must be tested. We physicists have been wrong before
in our claimed understanding of the universe, and there might be some presently
unknown physical phenomenon that allows cell phone microwaves to mutate DNA and
produce brain cancer. If the hypothetical effect is small, we could
miss it without even larger epidemiological studies.
OK, in the spirit of this approach, I’d like to propose an experiment
(for someone else to do) that would cost far less then the ongoing
epidemiological studies. The present state of molecular biology
technology is such that DNA of a specified sequence and length can be
synthesized by commercial firms specializing in the process. One can
also accurately measure the lengths of DNA strands by using electrophoresis
techniques, in which the mass of the DNA chain determines how slowly it
percolates through a porous medium in the presence of an electric field, with
the shorter, less massive DNA chains emerging first and the larger, more
massive chains emerging later.
Let us synthesize a particular DNA sequence of a specified length (say
1,000 or 10,000 bases) and place this in an aqueous solution in a vessel
actively maintained at body temperature. Two such vessels should be
prepared, with one held in isolation as a control and the other exposed to
intense microwave radiation for a given time, say 100 to 1,000 hours. Then
the solutions should be subjected to electrophoresis testing to look for
shorter DNA chains resulting from damage due to DNA breaks induced by cell
phone microwave radiation.
There will be some such damage due to natural radioactivity,
particularly carbon-14, and due to cosmic ray muons. However, I
confidently predict that there will be no significant observed difference in
DNA breakage between the irradiated sample and the control sample, independent
of the intensity and duration of the microwave exposure.
So, does anyone out there in the molecular biology community want to
undertake this test? You could probably get generous funding from
cell phone companies that feel harassed by the WHO.
Watch this column for experimental results, should anyone choose to
produce them.
AV Columns Online: Electronic reprints of about 150 "The Alternate
View" columns by John G. Cramer, previously published in Analog ,
are available online at: http://www.npl.washington.edu/av.
References
“Cellphone Radiation May Cause Cancer, Advisory Panel Says”, Tara
Parker-Pope and Felicity Barranger, The New York Times, May 31, 2011,
“Cell phone cancer report comes amid industry lobby”, Cecilia
Kang, The Washington
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