“Mechanism of Electromagnetic Field Interactions with Cells”
This was the topic of a presentation by Dr Martin Blank from Columbia University that he gave at the CSIRO Division of Applied Physics at Lindfield on 23 August 1996.Dr Blank is a founding member of the Bioelectrochemical Society. He was reporting some recent findings from his research concerning the effect of power frequency electric fields on body tissues. The following is a summary by Don Benjamin of Dr Blank s talk.
He said he was impressed by the cross disciplinary work carried out at Cambridge when he visited there and was working on colloidal science. He has always remembered this and his present work relies heavily on this interdisciplinary exchange of information.
There is wide agreement in the scientific community on the damage and cancer- causing effect of radiation in the ionising region of the electromagnetic(EM) spectrum; i.e. > 10^15 Hertz, or above in the ultraviolet region. There is no such agreement in the lower or non-ionising region. The question is does such EM radiation cause cancer? and if so, how?.
Recent controversies have occurred about cellular phones. In the US Larry King is suing Motorola following his wife s diagnosis with a brain tumour that he attributes to mobile phone use. Anecdotal evidence suggests higher incidence of brain cancers among mobile phone users. Is it real?.
The heating effect of microwaves on tissues is known. Is the effect still there and damaging as much lower, say, milligauss levels?.
Video display monitors emit EM radiation at about 10^4 Hz. This is mainly in the side fields. Laptop users are spared this particular hazard but their hard drive emits some radiation.
His work centres on the 50-60 Hz end of the spectrum.
Electricity power lines have an electric field gradient of about 10^3 V/m in the air below the lines but because of the attenuation effect at the skin (about 10-7) it is considered that this is unlikely to produce a significant effect within the body. The magnetic field does penetrate the body unimpeded. So this is likely to be the more important effect.
Evidence from early epidemiological studies (by Wertheimer and Leiper?) first suggested an increased level of leukemia among children who lived near power lines, the risk being elevated by a factor of about 2-3 times. A threshold level of about 2 milligauss was suggested. This study was ridiculed at the time, particularly by the electric power utilities on the grounds of poor methodology.
The New York electric power authority (Savitz) later repeated this study with better methodology an reached the same conclusions. Later studies in Los Angeles and Sweden replicated these results for childhood leukemia.
Another series of studies found an increased risk of breast cancer among telephone linemen of about 5-7 times. Since breast cancer is very rare in males such an increased risk was very interesting.
Evidence of the effect of EM radiation from the medical area has resulted in the US FDA approving therapies involving the use of EM radiation to promote bone healing following fractures. It is now accepted that magnetic fields can accelerate growth.
So what is the mechanism?.
The hypothesis offered is one of biosynthesis involving the formation of new chemicals affected by weak electromagnetic fields, probably magnetic fields.
If one considers the living cell as having a diameter of about 10 micrometers and subjected to a magnetic field the effect is one of an increase in the rate of protein production, including enzymes. One way this appears to happen involves a two stage process involving transcription and translation.
In the transcription stage the DNA unravels partially forming messenger RNA, (mRNA) that goes out of the DNA nucleus and latches onto the ribosomes in the cell fluid surrounding the DNA nucleus. In the second stage the protein is produced. There is also a feedback mechanism that controls how much of the protein enzymes are produced, depending on the body s needs. If one measures the rate of protein production or the enzyme activity with and without the presence of the magnetic field it is found that the activity increases in the presence of the EM field.
There is a known mechanism, formerly known as heat shock, whereby a cell produces extra protein/enzymes in response to shock such as thermal shock. These proteins are called heat shock proteins (HSPs). This is now referred to as a stress response rather than heat shock because the process apparently applies to any stress, not only thermal. EM radiation appears to be merely another form of stress on the cell.
One interesting result is that the response from increasing the magnetic field in a cell from 8 milligauss to 80 milligauss is similar to the effect of increasing the temperature from 37 deg C to 42 deg C.
Another interesting effect is the stress tolerance. When a cell has its temperature raised from 37 deg C to 45 deg C the cell will die within a few minutes. But if the cell s temperature is raised first to about 42 deg C, allowed to fall back to 37 deg C then raised to 45 C the cell doesn t die, as if the memory of the previous stress has conditioned the cell to cope with more stress than before.
There also appears to be a negative feedback mechanism operating whereby the HSPs reduce the rate of production of further HSPs. What are the implications for these effects with EM radiation? Does this mean that people subjected
to continuous or occasional low level EM radiation are more able to tolerate further EM radiation?.
What is happening at the molecular level? It appears that the process is one affecting the Sodium Potassium Adenosine Triphosphatase (Na-K-ATP-ase) pump that drives the cell.
Consider a continuous cell membrane (phospho-lipase). There are molecules that cross the membrane with one particular pear-shaped one having its narrow end extending beyond the outer edge of the membrane and its broader
end extending beyond the inner edge. This is the larger of a two-part molecule; the pear-shaped one is accompanied by a smaller elliptical part. Most of the interesting characteristics of the molecule occur in the part.
For this 100,000 molecular weight cell the ATP converts to ADP with the production of 3 Na+ ions and 2 K+ ions.
It is the business of these enzymes to use the energy from the ATP to get the Na to move out of the cell and the K to move inside. It appears to do this by modifying the permeability of the cell walls to allow these interchanges. This enzyme activity appears to be related to the movement of electric charge e-. Thus the movement of these positive ions through the is probably mediated by the movement of these negative charges and the amount of activity enhancement depends on the availability of these charges.
The enzyme activity is enhanced for magnetic fields at all enzyme activities but for electric fields is limited to low enzyme activity.
Any electric field present does not permeate the membrane. Instead it builds up a +ve charge on the outer layer of the membrane. Its ability to produce a corresponding -ve charge on the inner surface of the membrane relies on the scavenging of free charges within the membrane. So this enhancing effect is limited to low enzyme activities presumably because of the limitation of the availability of sufficient free charges within the membrane.
The quantity of charge/current density involved is quite large being equivalent to currents in a conductor of about 10,000 amperes; perhaps approaching superconductivity.
Summary (as written by Dr Martin Blank).
Interest in biological effects of electromagnetic (EM) fields continues to be stimulated by epidemiological studies that correlate increased risk of certain cancers with environmental EM field exposures. Correlations suggest causality, but many scientific questions about cellular mechanisms and signal transduction processes must be answered to assess the plausibility of the risk. Our studies of EM field interactions with cells provide significant insights into both the cell biology and the cell biophysics of the problem.
From analysing changes in the biosynthesis following exposure to EM fields, we have shown that EM fields stimulate the stress response, a cellular reaction to a variety of stimuli that cells interpret as harmful.
From studies of electric and magnetic signal transduction processes in a functioning membrane protein, the Na, K-atpase “ion pump” in cells, we have found that signal transduction always depends upon biological activity of the enzyme. Furthermore, the different effects in electric and magnetic fields can be explained by interaction of the field with moving charges during enzyme activity. This mechanism suggests that EM field-stimulated initiation of the stress response may involve direct interaction with DNA.
The systems studied are not esoteric or under unusual conditions. both biological systems are present in virtually all cells and the measured effects occur in the power frequency range and at EM field levels that are slightly above normal background.