Are mobile phones hazardous to human..? A lot of answer is available in dailies, magazines and internet. But all of them touches the matter in a superficial way. And this is because of the fact that the issue under consideration is inter disciplinary in nature-- ie; both electronics and medical science.
Nowadays cell phone is gaining popularity and the total number of phones sold worldwide during the year 2004 is expected to exceed 62 crore..! So the implication of mobile radiation on humans is a serious subject of research. But most of the research articles( especially in medical science ) these days approaches the issue in a statistical manner. In otherwords, they deals about a study conducted among some 500 no. of mobile users and coming under a conclusion. This type of statistical approach will never give a solid answer, even though their analysis is scientific.
So my review aims to put the problem in its proper perspective, by reminding how various applications of electricity and of communications appeared during the 20th century, and at what point potential hazards to human beings were detected. The interactions between handset antennas and biological tissues will be evaluated, in terms of the specific absorption rate (SAR). Until now, no convincing evidence was found that cellular phones could be harmful, as long as they are properly operated.
SOME HISTORICAL FACTS.
When electricity was invented and used for common purposes, people believed that , the current in the wire is flowing like water in a pipeline. They all aware of the danger of electricity when one came into contact with these wires. So precautionary measures were invented like proper insulation and earthing.
But, unlike water in a pipeline, the current in a wire radiates energy which is not visible to human eyes. Common men was not aware of this, and felt that he was safe as long as he never came into contact with the conducting wire directly.
But during the second world, huge antennas were erected, first to ensure transatlantic communications, later on regular broadcasting of radio programs, and then for television. At the beginning, the receiver sensitivity was very low, so that the transmitters had to pump a lot of electromagnetic power (at first mostly noise) into the atmosphere. Some people then absorbed considerable amounts of radiation, but apparently no one did worry about it at the time. Long distance effects of electricity are not easily perceived by the general public, because one does not see directly how a current, carefully contained within an isolated conductor, could affect someone at any distance from it. The concepts of electromagnetic pollution only appeared recently.
However, radars installed on board of ships were found to produce heat and burns when operating personnel came too close. The heating produced by microwaves was then evaluated and safety measures set up both for operating personnel and for the general public. Even high power radio broadcasting antennas will cause burns when people are near to it. So this is the difference between electric current hazard and electromagnetic one.
Thus , unlike electric current the nature of electromagnetic hazards is non-thermal. That is low power which are not directly linked to the heating of tissues, but to more direct interactions between the electromagnetic field and body cells. Such effects being to some extent comparable to those produced by radiation on sensitive electronic equipment. In principle, non-thermal effects could take place at lower power levels, but no conclusive evidence could be found that non-thermal effects can actually be harmful.
TECH FACTS.
The common belief is that the power is playing the major role in electromagnetic pollution. But I think the crucial part is the Frequency. Just listen....
Radiations are all part of a common spectrum known as electromagnetic spectrum. Radio and Microwaves are having very low energy(for a single photon) compared to higher contributers like Visible Light, Ultraviolet and X-rays. For extremely high frequencies, above the visible light range, a single photon has enough energy to pull an electron out of an atom, and thus to ionize it, so that such radiation is called ionizing. Chemical changes may then take place, which may induce tan and sunburn (ultraviolet rays) or, for the harder radiation (X and gamma rays), mutations or cancer.
At lower frequencies, in visible light, infrared, and all the frequency ranges used in communication purposes, the energy of a single photon is too small to ionize an atom: the radiation is then called non-ionizing. It is then the combined effect of many low energy photons that produces either thermal or non-thermal effects. Burns may result, due to excessive heating, when the radiated power absorbed exceeds a safety limit.
Thus exposure to radiation is very different in these two cases. It is the medical science to determine whether these low power, low frequency, non-ionizing radiations are hazardous to health. But, the gradual change of human genes or mutation is very difficult to predict. This changes in genes are not spontaneous. Its a gradual phenomena which takes some 20 or 50 years or more. Mobile phones are popular only in these days and the effect of these radiations will only occur gradually.
In general we can say that the use of mobile phone near the head will defenitely heats up the brain tissues even though the power radiated by the handset is very small ( some milliWatts ). But we have no equipment to measure these increase in temperature in our head. And if there is an increase in temperature in the head then we have no proof that it will cause a severe burn to brain tissues. The confusion still remains...But the ’burn factor’ is less serious than the ’ionizing factor’.
One more thing...all cell phone providers uses frequencies like 800MHz, 1800MHz etc. for communication and this frequency is somewhat ’ near’ to 2400MHz which the microwave oven uses to cook food..!!! But remember, in the microwave oven the power is very high compared to that of a mobile phone.
All of us heard that the headset and its connecting wire attached to the mobile phone will cause severe radiation to head. That is the connecting wire of the headset itself act as an antenna which carries radiations directly to the head...!! But I think this is somewhat absurd. Nokia and Motorola scientists are not fools to mix their voice signals with the transmitted one..! But remember that a piece of wire or metal near the radiation region will reflect electromagnetic waves. So it is wise to avoid that headset in your mobile phone. Instead always buy a mobile with a Handsfree( I mean a loudspeaker ) mode. By doing this you can always kept your phone away from your body while talking. Keeping the mobile away means you can minimize the power of the radiation entering your head a lot.
Another thing is that your mobile phone will radiate with a greater power when used in less range areas. So always speak when your phone has good recieved power strength as indicated in your phone’s screen.
Prevention is better than cure....
Thanks ..
Kannan.