Mobile phones use electromagnetic radiation in the microwave range, which may be harmful to human health. They communicate by transmitting radio waves through a network of fixed antennae called base stations.
Radio-frequency waves are electromagnetic fields, and unlike ionising radiation such as X-rays or gamma rays, cannot break chemical bonds nor cause ionisation in the human body. All radiations and fields of the electromagnetic spectrum that do not normally have sufficient energy to produce ionisation in matter are termed as non-ionising radiation. These are characterised by energy per photon of less than about 12 electron volts (eV), wavelengths greater than 100 nanometres (nm) and frequencies lower than 3×1015 Hz.
In response to public and governmental concern, the World Health Organisation (WHO) started the International Electromagnetic Fields (EMF) Project in 1996 to assess the scientific evidence of possible adverse health effects of electromagnetic fields. Given the immense number of people who use mobile phones, even a small increase in the incidence of adverse effects on health could have major public health implications. Because exposure to the RF fields emitted by mobile phones is generally more than a thousand times than from base stations, there is a greater likelihood of any adverse effect of handsets.
Health hazards
A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. An assessment was published in 2007 by the European Commission Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR). The research clearly showed an increased risk of traffic accidents when mobile phones (either handheld or with a hands-free kit) are used while driving.
Electromagnetic interference is also a major concern. When mobile phones are used close to some medical devices (including pacemakers, implantable defibrillators and certain hearing aids), there is the possibility of interference with their operation.
Other health effects of using mobile phones include changes in the brain activity, reaction times and sleep patterns.
Radiation absorption. Part of the radio waves emitted by a cellphone is absorbed by the human head. The rate at which the radiation is absorbed by the human body is measured by the specific absorption rate (SAR), and its maximum levels for latest handsets have been set by governmental regulating agencies in many countries.
SAR is defined as the time derivative of the incremental energy absorbed by or dissipated in an incremental mass contained in a volume element of a given density. SAR values are heavily dependent on the size of the averaging volume.
In the USA, the Federal Communications Commission (FCC) has set an SAR limit of 1.6W/kg, averaged over a volume of one gram of tissue, for the head. In Europe, the limit is 2W/kg, averaged over a volume of 10 grams of tissue.
Measurement of SAR value is a complicated process and comprises a phantom human head, specially developed liquids, a robot fitted with a measurement probe and a mobile phone powered up to its maximum certified power level.
Thermal effects. Tissue heating is the principal mechanism of interaction between radio-frequency energy and the human body. Tissue is a dielectric material which is heated by rotations of polar molecules induced by the microwave radiation.
At the frequencies used by mobile phones, most of the energy is absorbed by the skin and other superficial tissues, resulting in negligible temperature rise in the brain or any other organs of the body. In the case of a person using a cellphone, most of the heating effect occurs at the surface of the head, causing its temperature to increase by a fraction of a degree. The local blood flow mechanism of the brain is capable of disposing of excess heat. However, the cornea of eye does not have temperature regulation mechanism and is more prone to produce cataracts.
Long-duration cellphone usage also causes burning effects to the ear and ear-aches, or sharp pains inside the ear to the same side of the head as the phone is held. Some users even experience pain descending down from just behind the ear onto the jaw. Some users feel numbing sensations or tingling mainly in the outer area of ear, face or jaw.
Eye problems may include fluttering of the eyelids, blurring of vision and bloodshot eye—always in the eye nearest the cellphone. Several studies have indicated that low-level RF exposure due to cellphones could cause significant visual effects, including the destruction of corneal endothelial cells, increased vascular permeability and destruction of photoreceptors in the retina.
Non-thermal effects. Some biophysicists argue that there are several thermoreceptor molecules in cells, which activate a cascade of second and third messenger systems, gene expression mechanisms and production of heat-shock proteins in order to defend the cells against metabolic cell stress caused by heat. The increases in temperature that cause these changes are too small to be detected.
Some studies indicated that stress proteins are unrelated to thermal effects. These studies proved that stress proteins occur for extremely low frequencies (ELF) and radio frequencies which have very different energy levels. Some studies indicated a leakage of albumin into the brain via a permeated blood-brain barrier. Several other studies indicated that the blood-brain barrier breaks down with exposure to low-intensity cellphone frequency.
Cognitive effects. The impact of cellphone radiation on cognitive functions of humans has been studied by several researchers. These studies confirmed slower response to a spatial working memory task when exposed to cellphone radiation.
The Defence Evaluation and Research Agency (DERA), the UK’s largest science and technology organisation, has conducted research on cellphones’ EM radiation on the brain cells of rats and showed loss of memory for short periods. Several users of mobile phones also reported short-term memory loss. The cognitive functions are heavily affected by longer exposure.
EM allergic reaction. A number of studies have investigated the effects of mobile phone radiation specifically during and after its use. The users reported several unspecific symptoms like burning and tingling sensations in the skin of the head and extremities, sleep disturbances, dizziness, fatigue, loss of mental attention, reaction times and memory retentiveness, headaches, heart palpitations, blood pressure and disturbances in digestive system.
Most users reported pain or ache on the same side as they held the phone and normally in the temporal region. When pain is located on one side of the head, users can invariably reproduce it on the other side by switching ears in an effort to obtain temporary relief.
Genotoxic effects. Cellphone RF radiation at both 900 MHz and 1800 MHz and SAR of 0.4-27.5W/kg showed a correlation between increasing SAR and decreased motility and vitality in sperm, increased oxidative stress, stimulating DNA base adduct formation and increased DNA fragmentation. A European study named REFLEX (Risk Evaluation of Potential Environmental Hazards from Low Energy Electromagnetic Field Exposure Using Sensitive in-vitro Methods) indicated some evidence of DNA damage of cells in in-vitro cultures, damage to chromosomes, boosted rate of cell division and alterations in the activity of certain genes.
Cancer. A multinational case-control study on adults, INTERPHONE, coordinated by the International Agency for Research on Cancer (IARC), investigated whether the RF fields emitted by cellphones increased the risk of cancer. The study focused on tumours arising in the tissues most exposed to RF fields from mobile phones: glioma and meningioma (the most common types of brain tumours), acoustic neurinoma and parotid gland tumours. It found no increased risk of glioma or meningioma but there were some indications of an increased risk of glioma for those who reported the highest 10 per cent of cumulative hours of cellphone use.
However, it has been suggested that EM fields associated with cellphones may play a role in speeding up the development of an existing cancer. Some studies reported lump in the neck or ear (lymphomas) also.
Recommendations
To date, research does not suggest any consistent evidence of adverse health effects from exposure to EM fields at levels below those that cause tissue heating. The WHO has issued a precautionary principle applied in circumstances with a high degree of scientific uncertainty, reflecting the need to take action for a potentially serious risk without awaiting the results of scientific research. Some recommendations to minimise the possible health hazards are:
1. Keep the cellphone as far away from your body as possible. By moving the cellphone just 5 cm away from your head while talking on it, electromagnetic radiation that reaches to head is reduced by 75 per cent.
2. Turn your cellphone off at night because EM radiation emitted by the cellphone can disturb sleep quality.
3. Avoid carrying your cellphone in your pocket, on your belt or in your hand. If you do carry the cellphone in your pocket or hand bag, always position it such that the keypad faces towards you. This way the antenna faces away from you. Body tissue in the abdomen absorbs radiation more quickly than the head. The hip produces 80 per cent of the body’s red blood cells and is especially vulnerable to electromagnetic radiation damage. Close proximity may also damage fertility.
4. Consider using your laptop computer to make calls or send an instant message.
5. Avoid using wired headsets. Headsets including the ear buds that come with most cellphones today, act as an antenna, channeling electromagnetic radiation directly to the ear canal. When you use regular ear buds or ear pieces, you get three times more EM radiation than if you held the cellphone against your ear. Also, you get it directly into your ear canal, and ultimately to your brain. So it is recommended not to listen to music on a cellphone using headsets.
6. Use air-tube headsets with ferrite beads. Air-tube headsets are believed to be safer because these don’t work as antenna and EM radiation can’t travel up the air tube like it does on a regular wired earphone. Further, ferrite beads suppress EM radiation and dissipate it as heat. So, it is recommended to use airtube headsets with a ferrite bead placed as close as possible to the cellphone.
7. Use the speaker phone as much as possible. EM radiation decreases in direct proportion to the distance of the source from your body. So never hold the phone directly against your head.
8. Avoid making calls when travelling fast. Cellphones automatically increase output power when moving fast as these attempt to connect or handover to the next cellphone base station.
9. When purchasing a cellphone, get one with low SAR.
10. Avoid using a cellphone in metal enclosures like lifts, elevators, vehicles, subways and airplanes. Metal enclosures act like Faraday cage, trapping some of the radiation and reflecting it back upon you and others. So turn off your cellphone inside all metal enclosures.
11. Make calls when and where you have a strong signal. In most systems, the cellphone and the base station check the reception quality and signal strength, and increase or decrease the power level automatically, within a certain span, to accommodate for different situations such as inside or outside buildings and vehicles. When the signal is weak, cellphones automatically increase the power output, exposing you to greater EM radiation.
12. Limit the amount of time you talk on cellphones. Just a two-minute call on a cellphone may disturb the electrical activity of the brain for up to an hour. The more time you spend on mobile phone, the greater your risk of developing brain cancer. So keep your talking brief. You may be saving not only money but a life—quite possibly your own.
13. Use hands-free kit to decrease the radiation to the head.
14. Do not use telephone in a car without an external antenna.
15. The base of a cordless phone emits high levels of EM radiation, even when it is not being used. So use a regular phone as much as possible. Regular phones are the safest bet for conversation and work.
16. Avoid using a cellphone when you are pregnant. The developing organs of the fetus are most sensitive to any possible EM radiation exposure. Moreover, cellphones generate low levels of non-ionising radiation, which are more likely to cause behavioural issues in children after birth. High amounts of these waves can disrupt body tissues—that’s one reason why it is suggested to wear protective shielding when getting an X-ray done.
17. Don’t allow children to use a cellphone, except for emergencies. Children are at a greater risk because their skulls have not completely thickened. Children’s skulls are thinner and their brain contains more fluid than adults’. Exposure of young children to cellphone radiation may be more detrimental to their health, especially during the development and maturation of the central nervous system, immune system and critical organs. Electromagnetic fields easily penetrate through the brain of children, increasing the risk of cancer (see the figure). The electromagnetic field penetration in an adult and a child clarifies it.
18. Use a Bluetooth headset in order to minimise EM radiation. It has been found that Bluetooth headsets emit 1/100th the EM radiation of a normal cellphone. But whatever is radiated by this type of headset directly enters the ear canal and ultimately disturbs the electrical activity of the brain.
19. Use a cellphone radiation protection device which has a patented shield technology that superimposes a low-frequency noise-field onto the radio frequency to make it harmless to the body.
The author is a junior telecom officer in BSNL, Ludhiana, Punjab, and pursuing Ph.D degree in electronics engineering from Institute of Technology, Banaras Hindu University, Varanasi
