Cellular phones have, for many years generated heated debates and a multitude of studies costing billions of dollars. The problem with cellular phone studies largely resides in the fact that more funding is given to the groups that publish findings demonstrating a health effect, resulting in bias and manufacturing of the results. Cellular telephone companies also generate their own studies, though the public have no confidence in the results. Government agencies do not usually have sufficient funds to conduct large studies and are unable to accept exterior funding since the public would refute their results.
The issue with cellular phones is that their emissions are difficult to measure since they are placed in proximity of the head or body when in use. In addition, their Specific Absorption Rates (SAR) are often close to the limits of the various guidelines. SAR is defined as the amount of energy absorbed in a mass of tissue. The first thing to consider is that limit: In Canada, as well as in the U.S., the SAR limit is 1.6 Watts per Kilogram. That limit was chosen 50 times below the threshold where a health effect was found. Some compare the acceptable limit to that of a lethal substance and would like to have the current SAR limit lowered by a factor of 100 or more. Since the outcome of an overexposure to a lethal substance is death, and a radiofrequency overexposure is a heating effect, the two are non comparable.
How is SAR measured? SAR is measured by placing the phone on a fibreglass human phantom filled with a solution having the same dielectric constant and conductivity as the human brain. A robot then scans an electric field sensing probe in various locations of the head. At this point in time, the phantoms and procedures are in process of being standardized. Until an international standard has been established, results can vary more than 25 per cent in each lab, meaning that the SAR values written on the phones may not be accurate. Since Safety Code 6 allows for a large protection margin, there is no cause for alarm, but choosing a phone with a SAR of 1.2W/Kg over a phone measured at 1.4W/Kg does not mean that the energy absorbed from the radiofrequency emissions will actually be less (for the 1.2W/Kg phone).
How do cellular phones work? Cellular telephones operate by transmitting a radiofrequency (RF) signal to a base station, which will link to a central office (in the case of a land line), or to another base station. The cellular telephone network is divided into hundreds to thousands of cells throughout the city. When the cellular subscriber is in motion, it is likely that he will enter into a different cell, operated by another base station. This unnoticeable process is called "hand off".
I'm worried about my cellular phone, how do I protect myself? Health concerns such as headaches, nausea, lack of sleep and others have been blamed on cellular telephones. The most important factor to consider is how the telephone is held. Bending the head and pressing the telephone against the ear for a long period of time will likely cause headaches and other short term health problems. Also, it is a natural reaction to press the phone hard against the face since when it is hard to hear. For a long conversation, this will likely result in a heating sensation on the side of the face where the phone was placed. Finally, the batteries of the cellular telephone do get warm over time, which is not to be confused with RF heating. You will not perceive a heating sensation from cellular phones due to RF heating. The circulation of the blood in our body enables our system to remove heat from any particular area. There is not enough energy from a cellular phone to overcome the thermoregulation of the human body, therefore a heating effect is not possible.
Can I reduce the amount of RF energy I absorb? Concerned citizens have installed RF shields on their cellular telephones. If these devices do absorb RF energy, which is unlikely in many cases, the cellular telephone has to compensate by increasing it's power, which results in a more rapid decay of the batteries. It may also be important to consider that the closer the phone is to the base station, the less RF power is transmitted and vice versa. Headsets are most likely the best solution, as long as the cellular telephone is placed away from the body. Not out of fear of a health outcome, but simply because the there will be less RF energy lost from the telephone, which will likely increase battery life. Finally, there is no solution to talking on a phone while driving. The actual conversation is distracting, regardless of the use of headsets. There will most likely be a ban on using phones while driving in Canada in the near future. This is already in effect in some states.
