Engr. Anjum Iqbal
from Makkah Al Mukarrama
We all live surrounded by low-level Electric and Magnetic fields from power lines, electric appliances and electronic devices. The Biological effects of Low level non-ionizing fields are well established, but clear answer about adverse health effects continues to elude researchers.
What is electric field? What is Magnetic field? What are ionizing and non-ionizing fields? Let us say anything that carry electricity is surrounded by anelectromagnetic field. This field has electric and magnetic components that vary independently. The strength of electric component depends on voltage whereas the strength of magnetic field depends on current.
Magnetic component is actually responsible for biological effects. This is partly because much of the electric component is not effecting human body due to the shield provided by trees, building materials and clothing. Also, the body as a conducting medium attenuates the electric component by enormous factors. In the human body, the internal electric field induced by an external electric field is about one millionth to one hundred millionth of the applied field. On the other hands, the magnetic fields, in low frequency ranges are nearly unchanged as they pass through human body.
From time immemorial, Humans have been leaving on the surface of the earth in a natural relatively strong magnetic field--a static field of about 0.5 gauss or 500 milligass (mG) --which oscillates slowly over 24 hours period and varies over earth’s surface. Also, human have always lived in time varying natural electric and magnetic fields from thunderstorms and solar activity. The magnetic component of these fields is usually of low strength (about 0.1 mG) but can be as high as 5 mG during intense storms. The electric component can exceed 100,000 volts per meter during intense storms.
These are the natural magnetic fields humans are well experienced to live with. But the highest time varying magnetic fields (that oscillate fastest) to which humans are now exposed comes from man- made sources- electric power transmission & distribution lines and electric and electronic devices.
However average field in a house is about 2mG but under transmission lines it can go as high as 300 mG.
He current induced in the human body depends on the time rate of change of the magnetic field. Alternating fields such as 60 cycle per second field produced by Ac current sources are far more likely to have biological effects than steady DC fields. The emissions from a nominal 60-cycle source not all have a 60 c/s frequency. They sometimes contain very high frequency components extend into megahertz (MHZ )range. Most scientists ignored these fields when determining health effects.
In addition many common electronic devices, such as Hair dryers and electric shavers (which are used very close to human body exposes as high as 1000 to 5000 mg of fields, the exposure is limited as these equipment are used on for minutes per day. ). Microwave ovens, cellular telephones, television sets, video display terminal, have dominant fields which have frequencies more that 60 c/s.
In 1980s, cancer clusters have been the cause of public fear o EMFs This kind on cancer was notified in School children located near Power lines, in the police officers using Radar guns in America. Epidemiologist was greatly divided in their opinion but it was a hot topic for discussion at that time.
Studies of biological effects from low level non-ionizing fields are well established but clear answers to adverse health effects continue to elude researchers. Biological effects especially in laboratory tests; often differ depending on frequency, wavelength, angle between fields, and angle between Earth’s magnetic field and the applied field, also on type of amplitude (steady or pulsed). It some times vary with the order of application of fields of different intensity –such as weak-strong -weak or strong-weak, Weak- strong which can show different observations in the response of biological systems.
It is known that ionizing fields like X-ray and gamma rays can harm human tissues. They break molecular bonds, produce free radicals and damage DNA. Strong non-ionizing electromagnetic fields in the heating process in a Microwave oven This heating, even by a few degrees, can lead to damage in sensitive tissues.
Most scientist assumed that no biological effect could occur if the field is too weak to heat the tissues and the potential induced in living tissues by the external magnetic field is weaker than the natural potential across the cell membranes. The strongest 60 HZ field normally encountered in daily life is 1,000 to 5,000 mG, from a hair dryer or electric shaver. The highest potential gradient produced across the membrane by this kind of field would be on the order of tens of volts per meter (V per m). The natural gradient across cell membrane is about 10 V per m - which is much higher than the induced effect of commonly, encountered fields.
If this is the case than how the biological effects are possible?
In early 1980’s Scientists began to seriously consider the possibility that Athermal non-ionizing electromagnetic fields could have biological effects. Their interest in he research was stimulated by series of epidemiological studies on residential and occupational exposure to power frequency electromagnetic fields on School children near power High voltage transmission line was published in late 1979.
As a result of research, it was established that the low-level fields probably interact with living system by more than one mechanism. First, a process fairly complicated and not totally understood is related to intercellular two-way communication and resulting cooperation between cells The cell membrane which is made up of two layers of fatty phospholipid molecules with a total thickness of 40 A, keeps the cell inconstant contact with the intercellular fluid and the neighboring cells. Within the membrane are embedded many strands of protein that extend into the fluid surrounding the cell. Incoming electric and magnetic signals are received and accepted or rejected by(these) complex receptor molecules. Gap Junction, specialized regions of contact between adjacent cell membranes, couple cells electrically and chemically and greatly increase the capability of arrays of cells to detect weak signals from electromagnetic fields. As a result electromagnetic fields can affect the flux of biological messengers between cells. The modulation of intercellular communication through gap -- can change action of hormones, antibodies, neurotransmitters and cancer promoter molecules at their cell surface receptor sites. Electromagnetic field can cause Modification in shape and therefore the function of receptor molecules in the membrane, is another way of effects on hormones.
Three other mechanisms may also be important. Human brain like certain migratory birds also contains magnetic crystals. These crystals could experience a torque in weak magnetic fields, as does a compass needle. Preliminary evidence is available that specialized cells may contain thousands of magnetic crystals.
The second effect can be on recombination of free radicals. Free radicals, usually, exit for only nanoseconds in tissues before they recombine. Magnetic fields can cause free radicals to exits fewnanosecond longer thus slowing down the rate of heir recombination. The Concentration of free radicals in tissues may be slightly higher. Free radical spices are highly reactive and can damage DNA and many free radicals are known cancer promoters.
The third effect can be on Production of hormone melatonim from the pineal glad in the brain. The release of melatonim, both in humans and animals, from pineal gland during the night regulates body’s time clock. Studies show that magnetic fields can act on retina and the resulting signal may pass through the optic nerve to the pineal glad, where it directly reduces the out put of melatonin. Some studies suggest that magnetic field also reduce average melatonin level in humans. It is melatonin that inhibits breast, prostate and skin cancer by inhibiting tumor-enhancing hormones like prolactin and estrogen.
In these studies, the relative risks from living around high Electro-magnetic fields are in what epidemiologist called ‘noise level ’ of 1.5 to 3. (therisk ratio or relative risk , is the ratio of the disease incidence rate in the exposed population to that in the unexposed population. It is a useful research but most scientists are not convinced of a reasonably certain cause -and-effect relationship. Brief of various studies are summarized below:
( i.e. magnetic field exposure inside the house 0f 2mG or higher).
Scientists regards epidemiology as a blunt instrument and advocates that these studies can not be taken as enough evidence to say that electromagnetic fields are causing cancer.
CONTROLLED HUMAN STUDIES
In controlled human studies human volunteers are exposed to 60 Hz fields comparable to those found in workplaces and under large power transmission lines. The experiments are performed in double-blind conditions__ neither the volunteer nor the researcher knows when the fields are turned on.
Midwest Research Institute (MRI) observed significant slowing in heart rate, changes in electroencephalograms (EEG , which records electrical currents in the brain ), and changes in reaction time with exposure to electric and magnetic fields. A reduction of five beats per minute is occurred in 9 KV per meter-200 mG fields.
(* Three combined field conditions were tested. No effect is observed in 12 KV per m-300Mg and 6 KV per m- 100mG fields. Which proves effect of Amplitude “window” an amplitude that causes effects in the midst of two amplitudes one larger and one smaller that do not cause any effect. ).
Another curious result MRI finds is that the heart rate slowing occurred only when the volunteers are exposed to in the order field –sham - –field.
Sham means Zero filed condition. No significant effect in the order sham – field -field - sham is observed.
In EEG test, brain wave associated with concentration seemed to be disrupted at all levels of field strength. The effects were greatest soon after the field was switched on and again when it switched off. This means that changes in the exposure level is more important than the duration of exposure for producing effects in human beings.
MRI also observed that this effect did not persist much beyond the time of actual exposure to the field. The biological changes may or may not lead to disease with chronic exposure.
Very low frequency magnetic fields ( 2.5 Hz) are now being tested to see whether there effect on brain can be used to treat Parkinson Disease and epilepsy.
In animals, low level electromagnetic fields seem to have little effect on metabolism, blood chemistry and growth. However intense certain broad band pulses accelerate bone healing. Some patented medical devices uses this property that promote bone healing in humans. Rate develops faster in low level Electro magnetic fields. Animal fetus has no effect. Exposure of rate to Fields comparable to those near 500 KV lines, caused peak production of melatonin and other neurochemicals like norepinephirine, serotonin, and dopamine.
Human intelligence is observed to be reduced by few points in a large segment of exposed population. It also produce phase shift of neurochemicals in humans, this could cause sleep, and mood disorders and chronic depression.*
Several large scale animal studies suggest that power frequency ( 50 Hz ) electromagnetic field may enhance cancer rates ,they acts as cancer promoters rather than cancer initiator. Tumor promotion for both mammary & rodents and skin cancer for rodents is observed in controlled experiments. Rate of development of tumor is fast in em field-exposed rats.
CELL AND TISSUE STUDIES
Hundreds of studies indicate that low level athermal electromagnetic fields influence cell processes. One of these processes is the flow of calcium ions across the cell membrane. Calcium ion flow is an important means of transmitting extra cellular signals to the cell interior. It governs muscle contraction, egg fertilization and cell division.
In 1976, both halves of a newly killed Chick’s brain were placed in solutions to maintain natural cellular processes and one half was exposed to extremely low frequency fields. It was the first experiment that showed frequency and amplitude windows. At certain frequencies and amplitudes, the calcium ion efflux was decreased in the exposed half. The calcium ion efflux was not effected on certain frequencies and amplitude, some higher and some lower
than the those produced effect.
Later on it was shown that Numerical valves of Frequency and amplitude in the chicken brain experiment depends on the strength and orientation of a static magnetic field applied at the same time as the ac magnetic field.
It showed relation between applied magnetic field and the Earth’s magnetic field. Other kind of window effects were also observed i.e. the effect of 10 kV per meter field intensity resulted in four fold increased in tissues production of corticostererone where as 100 kV per meter field caused no effect.
Low level electromagnetic fields do not have sufficient energy to disrupt the structure of DNA. However, low intensity extremely low frequency have shown to change the synthesis rate of DNA in certain human cells and alter the transcription pattern of RNA, so that the protein produced in the cell
(Under the direction of RNA) do not have normal structure. Protein with abnormal structure would disrupt physiological functioning of the cell.
The effect of Em fields may not necessarily be cancer, a variety of other health endpoints, such as developmental effects and chronic depression, needs a close attention.
The exposures from Old Electric Blankets with 30 to 300 mG magnetic field strengths near the blanket surface are often greater than those from transmission lines or from many other house- hold appliances. New Blankets were designed to restrict the field Strength to 0.3 mG. The result is reduction in Magnetic field to less than 5 % but an increase in electric field resulting in higher induced currents in the human body than from the old-style blankets.
Scientists have reported risk of miscarriage among women who use electric blankets. The Epidemiological Studies designed to find a specific link between adverse health and blanket use haveshown mixed results.
BARRIERS TO REGULATION
If scientists eventually reach a consensus that low level electromagnetic fields do cause cancer or some other adverse health effect, then regulations defining some sage exposure level will have to be written.
Two peculiarities of magnetic fields make it difficult or impossible to define a safe exposure level with the currently available data. One is amplitude windows. Behavior of magnetic fields is not linear. That is, a higher dose may not necessary produce more of a biological effect than a lower dose. In some case higher dose may not produce any response at all, while a lower dose elicits a response. Therefore reducing fields may not make the field safe, in some cases it could in fact make them more dangerous.
Experimental evidences indicate that a 0.001mG is probably safer than 10mG field. Scientists do not have enough evidence to know that 3nG field is sager than a 6 mG field. Because of Amplitude Windows, it could turn out that the opposite is true.
Another factor that makes it difficult to write regulation in this regard is the measurement of the kind of exposure particularly for 60HZ field. Exposures can measured as: average field strength, average peak field strength , , average current or peak current induced in the body by fields, time spent in the field or number of times the field is switched on and off. Some Scientists believe that the individual risk any one of us faces, if it is real, is probably pretty modest and small compared to many risks in our day to day life.
The question “ Who may be at increased risk from electromagnetic field exposure? ” rather than “ what Level of exposure may be absolutely safe for the entire population ” is more important. Despite any agreement about what is a safe exposure level some state inAmerica have set limits for electric field intensity on the edge of transmission lines right of way. 9 1 to 3 KV per meter and 150 to 200 mG ). No national Government has yet issued standards in this regard.
Electrically powered trains and subways, magnetically levitated trains ( In Germany , measured field level at floor level is as high as 100 mG and at head level is 20 mG ) , superconductor energy storage, electric cars, electronic guide ways, and robotics can all produce high magnetic fields.
In India newly structured mobile towers, inceasing usage of computers, new Metro railways in mega cities and a jungle of non-technically approved electric Power Transmission and distribution networks contribute a heavy increase for individual exposure to electromagnetic waves with obvious health hazards but no measureable research & preventing regulations applied so far.
For the last 30 years grants of federal funds in America for research has been rather erratic. How ever several organizations , universities and research centers are spending 2 to 8 million multiyear program focused on effects of electromagnetic fields. Its effects on humans, primates, rodents, tissues, cells, gene, birth defect, miscarriages in humans, human epidemiology,personal exposure issues on humans, rats and mice, on Cancer in animals are under study. It includes producing a special polymer material that may have shielding properties. Over the years a great deal of cooperation and communication is benefiting the quality of research.
The research into the effects of electromagnetic fields is cross-disciplinary, highly complicated and has raised more questions than it has answered. So many years may pass before scientists have clear answers on cancer or other health problems that could be caused by electromagnetic fields. Society now has to decide how much it is willing to mitigate the cable.
Shifting thousands of already existing schools and residential housings from the vicinity of power lines would probably be a costly affair but new transmission lines, distribution lines or substation can installed away from the residential areas. And manufacturing video terminals and cellular phones so that nearly all the emissions are shielded could make them prohibitively expensive for many consumers.
It is known that no body is going to ban use of electricity, radio frequency and microwave electromagnetic fields in radio, TV, mobile phones Computers and other electronic devices. Even if we had perfect science, the policy debate will take its own time
Until research provides clear answers what should people do? It is Prudent Avoidance that can be done. It means avoiding or lowering exposure to
Electromagnetic fields. Avoid Electric Blankets made before 1990,Keep mobile phone as way from your body as possible, particularly never keep a mobile phone in your shirt front pocket closer to your heart ,move electric clocks away from the bed, move beds away from the walls that carry electric wiring, and use manual rather than electric appliances when not unduly inconvenient. For office workers it means not to situate a work right behind or beside another employee’s computer monitor or video display terminal. For police officers it means turning radar devices off when not in use or mounting the antenna outside the vehicle.
For other utilities it means routing new transmission lines away from residential areas and using line configuration that increase cancellation of magnetic fields between wires carrying different phases. For some utilities spending 4 to 5 % of the total cost to avoid potential problems with electromagnetic field will not be difficult.
The Electromagnetic Energy Policy Alliance ( EEPA )and association of manufacturers and users of electronic and electrical systems based in Washington D.C.cosidered “prudent avoidance” as fear for the unknown. EEPA argues that if prudent avoidance is used to set public policy it will man “ the national foundation of our modern technological world” is at risk.
A number of Government agencies all over the world who say officially that they would like to do research in this area are really doing very little. Avoiding research probably will not be an acceptable alternative. The public will continue to demand research funding and answers to these questions. -The End
In fact the research so far has raised more questions that it answered. So, many years may pass before scientist to have clear answers on health effects of electromagnetic fields. It may be too late.
* Like DOE, EPA, NIEHS, EPRI etc.