Cellular radio systems involve communication between mobile telephones (also called cell phones) and
fixed base stations. Each base station provides coverage of a given area,
termed a cell. While cells are generally thought of as regular hexagons, making up a "honeycomb" structure, in practice they are irregular due to site availability and topography. Depending on the base
station location and mobile phone traffic to be handled, base stations may be formed only a few hundred
meters apart in major cities, to several kilometers apart in rural areas. If a person with a mobile phone moves out of one cell and into another, the controlling network hands over communications to the adjacent base station.
Cell phones are powered by electricity and they use electric and magnetic fields (EMF),
also known as electromagnetic waves, to establish a wireless communication
link between a cell phone and the nearest base station. Generally speaking, when one is
talking the cell phone is giving off electromagnetic waves with information riding on them
while when one is listening the hand phone is capturing the wanted electromagnetic waves from
the space. Electromagnetic waves go out and come into a cell phone through its antenna.
As cell phone usage becomes more and more commonplace around the world,
so do concerns about their effects on health.
2. Electromagnetic Radiation and Possible Health Hazards
According to their biological effects, electromagnetic radiation can be classified into
two forms: non-ionizing radiation and ionizing radiation.
visible light waves
are non-ionizing radiation that
do not have enough energy to break apart atoms and molecules and turn them into ions,
which are electrically-charged particles.
This means that
"non-ionizing radiation does not damage genetic material (DNA)
in molecules directly and cannot therefore cause cancer or any other illness in people."
on the other hand, are forms of ionizing radiation,
which, particularly at high doses, can increase one's risk of cancer, birth defects,
and genetic defects through DNA mutations resulting from atom and molecule ionization.
It seems that "there is no completely safe level of ionizing radiation."
3. Biological Effects of Microwave Radiation
If exposure is sufficiently intense, microwaves can cause biological effects.
Possible injuries include cataracts, skin burns, deep burns, heat exhaustion and heat stroke.
Most, if not all, of the known biological effects from exposure to high-power microwave frequency sources are due to heating. The effects of this heating range from behavioral changes to eye damage (cataracts). Except possibly within a few feet of the antennas themselves, the power produced by cellular phone and PCS base station antennas is too low to cause heating.
Cell phones are low power radio devices that transmit and receive microwave radiation at
frequencies of about 900 Megahertz (MHz) and 1800 MHz. The possible health hazards of cell
phones can be classified into thermal effect and non-thermal effect.
- Thermal-effect: The main concern of non-ionizing radiation is the thermal
(heating or "cooking")
effect. Although cell phone radiates low level of power but if a small amount of power absorbed
by a human head concentrates on one very small area in brain so as to form a "hot-spot" then
a small volume of brain may be overheated ("cooked") and damaged. Besides low level of power
radiation from cell phone, scientific studies have confirmed that there is no significant
temperature rise (no hot-spot) in the brain due to cell phone radiation.
Actually, our body is like an air-con system, the blood circulation and lower ambient temperature
help to dissipate any heat absorbed and to prevent any hot-spot.
The thermal effect of cell phone is negligible.
In fact, a mild bout of exercise will heat your
head more than the puny microwaves that the cell phones emit.
- Non-thermal effect: Cell phones do have effects on people. Some people feel headache
after talking too long and some hypersensitive people fell sick when the cellphone is turned on.
These effects are mainly non-thermal effects and we do have a new explanation.
We believe that non-thermal effects are due to the waveforms (causing mechanical vibration) that
are determined by the frequency of carrier wave and the modulation that is way to put the information riding on the carrier wave.
The principle and effect of modulation may be explained using a very close example, music or sound.
Different music and sound have different waveforms, assuming the same small
volume one may feel
comfortable when listening some music or sound but fell uncomfortable or even sick when listening to
some other music or (noise) sound (like scratching glass using something).
It has been reported that certain waveforms can be used to cure some mental illnesses
such as depression, sleepless, etc. This shows that the nerve system of people could be affected
by the waveforms.
The fact is that most people are not so sensitive to the modulation of microwaves
but a very small number of people may be hypersensitive, liking they have the "sixth eyes"
and they may suffer with the symptoms of head ache, bad mood, etc. Another very close example is that
most people feel normal to take modern fast transportation tools such as bus, taxi, airplane, etc. However, some few people do
suffer from any fast transportation means, including bus, taxi, etc.
In general, short term of those non-thermal (mechanical vibration) are usually reversible and
the symptom will disappear when the cause is gone. But the long-term effect is still not clear.
More studies are needed.
Even at high levels of exposure, there is no substantial evidence that microwaves can
either cause or contribute to cancer. Although research in this area has been extensive,
there is no replicated laboratory or epidemiological evidence that microwaves at the power levels associated with public exposure to microwaves from cellular phone and base station antennas are associated with cancer.
4. Comments on Confused Studies
Based on most recent reports, all previous studies that indicated a cancer risk use power levels
far above those found in publicly-accessible area and neither studies have been
In 1995, researchers at the University of Washington, Seattle, found DNA breaks in cells exposed to wireless phone radiation. If this was right, it would completely change the way we think about radiation. Subsequent attempts by researchers at Washington University in St. Louis to duplicate the work were unsuccessful, an indication that the first work might have been flawed.
One American research group showed a near tripling of a statistically significant risk of a rare kind of tumor called a neurocytoma among cell phone users, compared with people who do not use cell phones. The result of that study, however, is undercut by the fact that the data did not show that the risk of neurocytoma rose with the amount of cell phone use, which researchers would have expected to find. In fact, greater exposure was associated with lower risk.
Another epidemiological study found that right-handed people who used cell phones and had brain tumors tended to have them on the right side of the head -- a result that could show a link to radiation from the phones. However, no such correlation appeared in left-handed cancer patients.
In 1997 came another bombshell that is now being called into question. Researchers at the Royal Adelaide Hospital in Australia spent 18 months exposing mice to radiation mimicking the emissions of digital mobile phones and found that twice as many of these mice developed lymphomas as did animals not exposed to the radiation.
But since then, three other teams have failed to find similar evidence of increased cancer rates among mice exposed to microwave emissions. To increase the sensitivity of the experiment, the Australia team used mice that had been genetically engineered to be susceptible to lymphoma.
In the latest study, a team of microwave experts at the Brooks Air Force Base in San Antonio, Texas, used mice genetically engineered to be susceptible to breast tumors. They exposed the animals to microwaves for 20 hours a day for 18 months, yet saw no increases in tumor rates.
The Australia team is reserving judgment about the cancer link until researchers in Australia have repeated the original experiment using the same strain of mice and exposure conditions. "If they don't come up with the same result, that'll be a happy outcome," the Australia team says.
An even happier outcome would be if microwaves turned out to be good for you. It sounds crazy, but a couple of years ago a team at the Veterans Affairs Medical Center in California, found that mice exposed to microwaves for two hours a day were less likely to develop brain tumors when given a cancer-causing chemical. But nobody has yet replicated that finding either.
It was also reported that non-ionizing radiation may
speed up the cancer though it would not cause cancer.
However, so far the evidence from biological studies on possible effects on tumor promotion or progression, including work with experimental animals, is not convincing.
In 1998, fears about mobiles affecting brain function received fresh impetus thanks to work at the Defense Evaluation and Research Agency's labs (UK). A scientist exposed slices of rat brain to microwave radiation and found that it blunted their electrical activity and weakened their responses to stimulation. Because the brain slices were taken from the hippocampus, a structure with a role in learning, the results were seized upon as further evidence that mobile phones could scramble human memories.
In fact, the implications are far from clear. In people, the hippocampus is buried too deep in the brain to be influenced by emissions from mobile phones, says the same scientist. And his latest findings have undermined fears about memory loss. One result, for instance, suggests that nerve cell synapses exposed to microwaves become more--rather than less--receptive to undergoing changes linked to memory formation.
We are seeing the variation from lab to lab that you would expect from technically demanding experiments that are trying to pick up tiny effects.
Several studies use RF radiation intensities that substantially exceed anything that would be found in public areas near a safety-standard-compliant base station.
Some of the experiments may also be plagued by systematic errors. One problem is that microwave emissions can interfere with electrodes and other instruments, leading to all manner of false readings. Another is that researchers often have a hard job ensuring their equipment doesn't induce heating effects that could never be caused by a mobile phone.
5. Future Trend
Electromagnetic radiation is everywhere.
More and more wireless communication services (cellular phones, paging, wireless Internet)
are expected so is the artificial electromagnetic radiation.
The number of wireless phone users are exploding. It is predicted that there will be more wireless Internet accessing than wired Internet accessing in future. It is predicted that there will be 1.2 billion wireless device users around the world by 2005 and
2.7 billion in 2015. It seems that there is no way to reverse this trend. Too much electromagnetic radiation is a type of environmental pollution and should be controlled.
Scientists and engineers are developing better and safer wireless systems and devices.
Smaller cell size, better base station antennas and other more advanced technologies will allow future cell phones to radiate much lower power. It is certain that future cell phones will be safer, smaller and with longer battery life.
Using cell phone while driving might be the biggest hazard cell phones can cause.
Paying attention to drive your car when you're using cell phones.
Besides, you may adopt some of the following ways to minimize the radiation of the mobile phone.
- Shorter conversations.
Avoid speaking for long periods on the cell phone.
Try to plan your calls in such a way that you use ordinary phones for long conversations.
Speak as little as possible inside the car:
because the reflection from the car cavity may amplifies the radiation.
If you have to speak a lot from the car - get a roof antenna.
- To use plug-in earpiece:
Plug-in earpiece will separate the antenna further away from your head/body.
- Try a CDMA phone if you are hypersensitive to a GSM one:
If you fell headache or uncomfortable when using a GSM phone,
you may be hypersensitive to the modulation of electromagnetic waves.
People are less sensitive to CDMA phones.
Newer CDMA system works differently than GSM system and doesn't emit
the sharp-edged lower frequency pulses.
The digital RF signal more resembles a noisy analogue signal and is also likely to be less bio-active.
This may also be one reason to push industry to replace GSM systems with CDMA systems.
The output from mobile phones results in only a fraction of this amount of energy being deposited in the tissues of the head, and therefore the rise in temperature is only be a fraction of a degree. This is similar to the normal daily fluctuations in body temperature and such small changes in heat load are considered to be too low to cause adverse effects.
The waveforms of cell phone radiation may affect some hypersensitive people,
causing adverse physiological effects. Few studies have yet investigated these possibilities, but
the evidence does not suggest the existence of an obvious health hazard.
US Federal Communications Commission (FCC) concluded that
There is no scientific evidence to date that proves that wireless phone usage can lead to cancer or a variety of other health effects, including headaches, dizziness or memory loss."
US Food and Drug Adminstration (FDA) concluded that
The available scientific evidence does not show that any health problems are associated with using wireless phones. There is no proof, however, that wireless phones are absolutely safe."
UK's National Radiological Protection Board (NRPB) concluded that
"The totality of the evidence available does not suggest that the use of mobile phones
have any detrimental effect on human health. Nevertheless, there does remain a need for further