updated Jan 22, 2013; Melbourne, Australia; Jan. 21, 2013:
In my written testimony, submitted for the hearing before the US Senate in September 2009, I have written the following, concerning the impact of cell phone radiation on brain temperature (bold coloured text – emphasis added now by DL):
“…the radiation emitted by mobile phones might induce temperature hot spots within the exposed biological material, i.e. small areas where temperature might rise more than in the neighboring areas. We can detect and measure hot spots on the macro-scale but we do not have yet technology to measure whether hot spots are created on the micro-scale (sub-cellular-scale). Presently, dosimetry and modeling of the distribution and intensity of mobile phone radiation in the brain uses as a model plastic container molded in the form of half-head and filled with “physiological solution” consisting of water, salt and sugar. Such model represents human head with skull (plastic mold) and brain (water solution of salt and sugar). However, it is a great oversimplification of the reality.
Living tissues and cells are not homogenous environments but they are compartmentalized into cells and sub-cellular size volumes (organelles) that are delineated by lipid-containing hydrophobic membranes. Charged biological molecules and ions, unlike in the above mentioned “head model”, are not distributed within the tissue or cell uniformly and can’t travel freely. Thanks to the membranes and their selective transport mechanisms the distribution of molecules and ions in cells is non-uniform and produces electric gradients that play a paramount role in physiological functioning. Strong electromagnetic fields can disrupt the function of selective transport mechanisms of the membranes and cause profound physiological changes (e.g. electroporation).
The question to be answered is what happens when such hydrophobically compartmentalized environment is exposed to weak electromagnetic stimulus like mobile phone radiation. Will such exposure lead to formation of thermal hot spots on sub-cellular scale, because the free flow of charged molecules and ions is prevented by the selective transport mechanisms? Formation of such sub-cellular hot spots could cause changes in certain functional areas of the cell that eventually could lead to alterations in cell physiology. There have been identified the so-called temperature-sensing molecules in the cell membranes. When activated by temperature change these molecules send stress signals that may reach cell nucleus and may affect expression of genes and, as a consequence, alter cell physiology. However, we still do not know whether the activation of cellular stress response, observed in some studies, is caused by the activation of temperature sensing molecules in cell membrane by the mobile phone radiation or some another event.
In my opinion, it is possible to expect that the mobile phone radiation might affect cells by the combination of thermal and non-thermal (if they exist) mechanisms. Thermal effects, induced by mobile phone radiation, should not be automatically regarded as unimportant in context of health risk evaluation because their occurrence and kinetics are different from the harmless physiological warming up of the body. Unfortunately, the presently available technologies do not yet permit to measure temperature or mobile phone radiation distribution on sub-cellular scale. On the macro-scale of groups of thousands of cells, that are presently measurable, such sub-cellular hot spots would not be detectable.
From the point of view of the safety of mobile phone users, the issue of induction of biological (and possibly health) effects by thermal or non-thermal mechanisms should be put to rest. Continuous talk of the harmlessness of thermal effects induced by temperature rise up to 1oC and the continuous dispute whether non-thermal effects exist is misdirecting science and is taking attention from the important issue – if there are any effects induced by mobile phone radiation at levels permitted by the present safety standards that can alter normal physiology…”
The sentence marked above in bold red font might be now outdated.
PNAS published on Jan. 2, 2013 an article where scientists were able to measure temperature distribution in brain (including hot-spots) using NMR technology.
This study might open a new era in studies of the cell phone radiation effects on human brain because we will be able to determine the 3-D distribution of temperature changes in human brain that are caused by cell phone radiation. This will allow setting up better experiments to examine small thermal effects on function of human brain cells and brain as a whole.
We now know that both thermal and non-thermal effects of cell phone radiation exist. And we know that both can cause measurable biological effects.
We now need to find out what the non-thermal effects and the small-thermal effects can cause to living tissues before we can definitely answer the question of the existence of health effects. Hopefully the new NMR technique will help us in this endavour.
In the News Science story published by the Australian ABC News on Jan. 18, 2013, Rodney Croft commented the NMR-study as follows:
“…Professor Rodney Croft, director of the government-funded Australian Centre for RF Bioeffects Research says, to date, research with phantoms suggests heating from mobile phones is unlikely to be a problem.
“It is very, very small and is not likely to be large enough to cause an effect because it’s many times lower than the brain and the body is used to dealing with,” says Croft.
He agrees the technique developed by Gultekin and Moeller will be useful in validating the models used to date.
But, says Croft, while striving for greater accuracy is important, the research is a bit “academic” because currently there is no evidence of any actual problems from mobile phones.
He says even if measurements made in humans are different to those made in phantoms this will probably not matter because the level of heating involved in the first place is so small.
“Certainly there are going to be differences but I don’t think they’re going to be appreciable,” says Croft.”
I certainly disagree with Rodney. What he says fits rather statement of religion than of science. He beliefs… because neither he nor we know the real impact of cell phone radiation on the temperature of the sub-cellular structures in human brain. We had no suitable scientific techniques to measure it. Current models that represent human brain as “plastic bucket filled with water and sugar and salt”, where ions can move freely, do not meet scientific scrutiny. Such models were acceptable when, long time ago, the computing power of our computers was low. But now whe should revisit these issues and use representative models, not buckets with water. New approach with NMR might be the way to progress…
Lastly, lets not jump up to premature conclusions that there is no evidence of any health effects. There are plenty of red flags. We need to dilligently follow them before we can, with any degree of certainty, say that there are, or there are not, health effects. Examining temperature distribution in brain will certainly help to prepare better designed studies to examine mechanisms of the cell phone radiation effects observed in numerous studies.
This is real science needed in real life, this is not an academic only debate.
Update Jan. 22, 2013
One of the readers, in e-mail to me, experssed the following concern about PNAS study:
“…Two problems: NMR produces it’s own heat when scanning brain tissue via the strong magnetic field and pulsed RF, and brain tissue does not dissipate heat as effectively as the rest of the body. The skull is a resonant cavity that can augment some exposures...”
David H Gultekin, co-author of PNAS study responded as follows:
“…The issue here is the measurement of radiation absorption. Heating is the result of absorption and becomes detectable when heat accumulates and the temperature starts to raise above normal. NMR can also cause heating with certain RF intensive pulse sequences. However, RF pulse sequences with very low SAR are used for thermal imaging. This is easily verified by performing an imaging test run without switching the antenna on. The perfusion of tissue is relevant to the temperature raise during in-vivo measurements…”