01.07.2009

Calling at a Cost

While there is significant controversy about the use of mobile phones and whether they will cause or contribute to particular diseases, there is no doubt they have the potential to cause harm.

A serious problem lies with our inability to measure the relationship between our exposure to radiofrequency radiation and resulting disease. Just as difficult is separating out the roles of vested interests. While the weight of evidence from industry and government studies suggests there is little, if any, problem, most evidence from independent studies indicates there are very serious issues that require careful consideration. However, once technology is rolled out it is almost impossible to roll it back.

The problem with mobile phones is that they emit radiofrequency from the base station antennas, producing low but continuous exposure to entire communities and to the mobile phone or handset, which produces intense, intermittent exposure to the head of the user. Mobile telephones operate on sending and receiving frequencies in the approximate range of 825 MHz to 915 MHz, although with the continued expansion of this technology, the range of frequencies to which users are potentially exposed may be broadened to 450 MHz to 2500 MHz. The antenna of the phone radiates power equally in all directions at peak levels of 1-2 when the phone is operating. A low frequency magnetic field is also emitted from the phone. This is associated with surges in electric current from the battery, generally in the range of 0.125 W-0.25 W.

The amount of this radiation actually absorbed by the user varies according to the amount of power emitted from particular phones. The amount of power depends on design factors such as make, model and type of aerial, as well as individual use of the device-including the proximity of the phone to the ear or skull, the orientation of the phone and the use of "hands-free" phone kits. The proximity of the phone to the user's head has been found to have the most significant relationship between mobile phone use and the amount of microwave and radio frequency radiation the head absorbs.

When the phone is in contact with the head, the amount of power that is absorbed decreases exponentially as the phone is moved farther away from the ear. That is, exposure to the radiation decreases a lot with just a small move of the phone away from the head. The amount of power that is absorbed can decrease by as much as 25 per cent with the phone being placed one centimetre from the head when in use. "Hands-free" kits are also a practicable means of reducing exposure to radiation by two orders of magnitude, due to the increased distance of the phone to the sensitive tissues of the human body. Similarly, the use of the speakerphone held away from the head can also dramatically reduce exposure.

Health effects

The effects of non-ionising radiation from mobile phones can be broadly categorised into thermally (heat) induced and non-thermally induced biological effects. Non-thermal effects of mobile phones include headache, memory problems, increase in frequency of seizures in children, decrease in duration of deep sleep and inhibition of secretion of melatonin.

Typical effects that have been noted in human studies include radiofrequency sickness, electroencephalographic changes, cell proliferation, blood pressure changes and blood-brain barrier leakages. Also confirmed have been transient, but significant, modifications in dermal or cutaneous blood flow as a result of standard operation of mobile phones. There are many less severe effects linked to mobile phone use; these include headache, sore muscles (radiating from the ear to the temple and through the shoulders) and sleep disturbances.

There is also growing concern about the potential contribution of mobile phones to brain cancer, leukaemia and acoustic neuroma (a particular tumour) in the head and neck. Few epidemiological studies have managed to confirm a solid link between mobile phone usage and tumour formation; making such links is extremely complicated due to issues such as the latency period between exposure and onset of symptoms. It may also be due to the strong industry bias in research.

However, several population and surrogate studies have produced alarming results. In a national US study, a significantly increased incidence of neuroepithelial tumours was found to be consistent with mobile phone usage. This was indicated by increased DNA strand breaks and chromosomal aberrations, which promote the development of tumours. Other studies have reported similar findings, noting changes in the development of enzymes associated with carcinogenesis after exposure to radiofrequency radiation. This suggests that the influence of radiofrequency and microwave radiation is more localised to the source of the energy and perhaps aided by the ability of radiofrequency radiation to interfere with the blood-brain barrier. This is supported in surrogate studies on animals, which showed influences on immuno-reactivity and neurotransmitters within the brain.

The impact of radiofrequency on male reproductive organs is also an area of increasing distress due to the known interference of radiofrequency and microwave radiation on the testes. A recent study found that electromagnetic radiation from mobile phones interferes with human sperm motility, the ability of the sperm to progress through the reproductive tract. This is of prime concern as this interference may lead to structural and behavioural changes in the male sperm cell that may not be apparent until later in life. In a study of laboratory animals exposed to low-energy radiofrequency radiation (that is, from a mobile phone), the exposure group experienced higher percentages of non-progressive or no-motility sperm. This could generate problems in the future for many, given the young age at which individuals start to use mobile phones.

While there are many concerns about the use of mobile phones, most governments are locked into the continued and expanded use of these devices. Authorities around the world are vague on the subject of mobile phones, mainly because of economic reasons. Despite this, the World Health Organisation recommends that one limit time on mobile phones and use hands-free devices whenever possible. The WHO also advises to use a "land line" phone when available, limit the duration of mobile phone conversations, fully extend the phone's antenna where possible (ie, if the phone has an external antenna) and use one's mobile phone in an open area so the phone transmits at a lower power level.

The controversy about the health effects of mobile phones is illustrated by a 2001 report from the Independent Expert Group on Mobile Phones, which stated that children under the age of 16 should be discouraged from using these devices. The reason for this recommendation is the potential for children to absorb more energy from radiation as a result of their relatively smaller head sizes, thinner skulls and higher tissue conductivity. The age recommendation was lowered to 10 years in 2004. This was due to pressure from the mobile phone companies, especially given that teenagers are probably the biggest users of mobile phones and these companies could have lost a significant portion of a growing, captive market.

Mobile phone towers are another big potential problem. They emit microwave signals in a relatively wide beam. These emissions have intensities that are quite high at close range to the antenna but which drop in intensity with distance. By any measure, the level of the signal is relatively low on the ground, but residents nearby are exposed to these emissions 24 hours a day. No one knows the long-term effects of this type of exposure or the range of susceptibility.

Peter Dingle is an environmental and nutritional toxicologist and Associate Professor in Health and the Environment at Murdoch University.

 
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