Mobile phone radiation and health

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A Greenfield-type tower used in base stations for mobile telephony
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A Greenfield-type tower used in base stations for mobile telephony
A modern mobile phone (Samsung)
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A modern mobile phone (Samsung)

Mobile phone radiation and health concerns have been raised, especially following the enormous increase in the use of wireless mobile telephony throughout the world (as of August 2005, there were more than 2 billion users worldwide). This is because mobile phones use electromagnetic waves in the microwave range. These concerns have induced a large body of research (both epidemiological and experimental, in non-human animals as well as in humans). Concerns about effects on health have also been raised regarding other digital wireless systems, such as data communication networks.

The World Health Organization has officially ruled out adverse health effects from cellular base stations and wireless data networks, and expects to make recommendations about mobile phones in 2007-08.[1] In December 2006, a 21-year Danish study with 420,000 participants (considered a large, reliable, study of long-term effects) publised in the Journal of the National Cancer Institute ruled out any causal link between cell phones and cancer.[2]


Contents

[edit] Health hazards of handsets

Calculated specific absorbed radiation (SAR) distribution in an anatomical model of head next to a 125 mW dipole antenna. Peak SAR is 9.5 W/kg over 1 mg, average 0.008 W/kg. (USAF/AFRL).
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Calculated specific absorbed radiation (SAR) distribution in an anatomical model of head next to a 125 mW dipole antenna. Peak SAR is 9.5 W/kg over 1 mg, average 0.008 W/kg. (USAF/AFRL).

Part of the radio waves emitted by a mobile telephone handset are absorbed by the human head; the radio waves emitted by a GSM handset, for example, can have a power of up to 2 watts, and an analog phone in the USA (probably very few in use today) can have 3.6 watts, as in the old large mobile phone units installed in cars. Other digital mobile technologies, such as CDMA and TDMA, have today lower rates, under 1 watt. The average radiation rate of cellphones in some countries is regulated and it is mandatory to inform the consumers about it (usually printed in the battery compartment). In some systems the cellphone and the base station check reception quality and signal strength and the power level is increased or decreased automatically, within the above limits, such as inside buildings or vehicles, etc.

The rate at which radiation is absorbed by the human body is measured by the Specific Absorption Rate (SAR), and its maximum levels for modern handsets have been set by governmental regulating agencies in many countries. In the USA, the FCC has set a SAR limit of 1.6 W/kg, averaged over a volume of 1 gram of tissue, for most parts of the body. (SAR values are heavily dependent on the size of the averaging volume. Without information about the averaging volume used comparisons between different measurements can not be made.)

[edit] Thermal effects

Microscope photographs of lenses incubated in organ culture conditions for 12 days. Right frame shows Control lens with no damage. Bottom frame demonstrates the effect of microwave radiation on bovine lens sutures for a total exposure of 192 cycles (1.1 GHz, 2.22 mW). Each cycle lasts 50 min followed by 10 min pause. In the absence of microwave radiation, the bubbles are generated by temperature increase to 39.5 °C during 4 h; see left frame. Credit: IsraCast Technology News [2]
Enlarge
Microscope photographs of lenses incubated in organ culture conditions for 12 days. Right frame shows Control lens with no damage. Bottom frame demonstrates the effect of microwave radiation on bovine lens sutures for a total exposure of 192 cycles (1.1 GHz, 2.22 mW). Each cycle lasts 50 min followed by 10 min pause. In the absence of microwave radiation, the bubbles are generated by temperature increase to 39.5 °C during 4 h; see left frame. Credit: IsraCast Technology News [2]

One well-understood effect of microwave radiation is dielectric heating, in which any dielectric material (such as living tissue) is heated by rotations of polar molecules induced by the electromagnetic field. In the case of a person using a cell phone, most of the heating effect may occur in the head surface, causing its temperature to increase by a fraction of a degree. The level of temperature increase is an order of magnitude less than that obtained during the exposure of the head to direct sunlight. The brain's blood circulatxdfhgfchxcgnzcgjnzfhjzgfkjzdtg, cgjfdghxfgxfgdfxgdfxhfdgfgion easily disposes of excess heat by instantaneously increasing local blood flow. However, the cornea of the eye does not have this temperature regulation mechanism. Premature cataracts are known as an occupational disease of engineers who work on high power radio transmitters at similar frequencies.[citation needed] Due to the low power of mobile phones, cataracts have not been reported to occur in users of these.

It has been claimed that some parts of the human head are more sensitive to damage due to increases in temperature, particularly in anatomical structures with poor vasculature, such as nerve fibers. More recent results from a Swedish scientific team at the Karolinska Institute (Lonn, Ahlbom, Hall and Feychting) have suggested that continuous use of a mobile phone for a decade or longer can lead to a small increase in the probability of getting acoustic neuroma, a type of brain tumor. The increase was not noted in those who used phones for less than 10 years. The study has been criticized for possible problems in data analysis such as recall bias. However, another study conducted by the Swedish National Institute for Working Life supported an increased risk of "malignant tumors on the side of the head the phone is used." [3] Such long term heavy use involved phones of older higher power analog designs that were first introduced to Sweden in 1984, earlier than many other countries.

No increased cancer risk was found in a larger and more recent study, and the hypotheisized link is now generally regarded as having been ruled out.[2]

[edit] Non-thermal effects

In December 2004 a pan-European study named REFLEX, involving 12 collaborating laboratories in several countries showed some compelling evidence of DNA damage of cells in in-vitro cultures, when exposed between 0.3 to 2 watts/kg. This overlaps with the level of radiation typically emitted by digital cell phones of around 0.2 to 1 watt/kg. There were indications, but not rigorous evidence of other cell changes, including damage to chromosomes, alterations in the activity of certain genes and a boosted rate of cell division. [4] The results of this study run contrary to many similar studies that were conducted before and showed no increase in DNA damage. [5].

According to a recent (2004) review published by the UK National Radiation Protection Board (Z J Sienkiewicz and C I Kowalczuk [6]), "the effects reported by the REFLEX project do not appear to have been seen consistently (...) Overall these inconsistencies do not suggest that robust responses have been observed. The physiological significance or biological relevance of some the reported changes were questioned by the authors themselves (e.g., "Taken together, the results of the REFLEX project were exclusively obtained in in vitro studies and are, therefore, not suitable for the conclusion that RF-EMF exposure below the presently valid safety limits causes a risk to the health of people"). A comment by Boulder (2005) on these results questions "whether the positive findings were more common than expected from random chance (false positive rates from cellular genotoxicity tests can be as high as 20%)." The results of a long-term study announced in 2006 found no increased cancer risk, and the hypotheisized link is now generally regarded as having been ruled out,[2] [3]

The communications protocols used by mobile phones often result in low-frequency pulsing of the carrier signal. These low frequencies are similar to those that exist in the electrical oscillations of the human body, specifically the alpha and delta brain waves. Non-linear interactions could theoretically result when resonances are created when the brain is subjected to mobile phone radiation, in a manner similar to that observed when light strobing induces photosensitive epilepsy in susceptible individuals. No experimental results have indicated this theoretical possibility, however. These and other non-thermal effects are summarized in (Hyland, 2000).

Other researchers have argued that the so-called "non-thermal effects" could be reinterpreted as a normal cellular response to an increase in temperature. The noted German biophysicist Roland Glaser, for example [7] has argued that there are several thermoreceptor molecules in cells, and that they activate a cascade of second and third messenger systems, gene expression mechanisms and production of heat shock proteins in order to defend the cell against metabolic cell stress cause by heat. The increases in temperature that cause these changes are too small to be detected by studies such as REFLEX, which base their whole argument on the apparent stability of thermal equilibrium in their cell cultures.

[edit] Electromagnetic hypersensitivity syndrome

Many users of mobile handsets have reported feeling several unspecific symptoms during and after its use, such as burning and tingling sensations in the skin of the head and extremities, fatigue, sleep disturbances, dizziness, loss of mental attention, reaction times and memory retentiveness, headaches, malaise, tachycardia (heart palpitations) and disturbances of the digestive system. Some researchers, implying a causal relationship, have named this syndrome as a new diagnostic entity, EHS or ES (electrosensitivity). The World Health Organization prefers to name it "idiopathic environmental intolerance", in order to avoid the implication of causation. This entity is quite controversial, because albeit identified in unmistaken terms by the patients who affirm to suffer from it, in some cases in such a radical way that they avoid using cellphones, it has not been recognized as a separate clinical entity by most medical researchers.

Two recent literature reviews, however, one reviewing 13 published papers in 2003 and 2004, and another reviewing 31 papers published before 2004, have concluded that there is no scientific evidence for a causal relationship between the reported clusters of symptoms and exposure to microwave radiation used in cellphones, well below the safety standards. A workshop conducted by the WHO in Prague in 2004[4] also reached the same conclusions, viz., that 1) reported symptoms are very unspecific and could have other causes; 2) there is no causal association demonstrated between exposure and symptoms, 3) that patients who display those symptoms should be medically examined for alternative explanations and causes, including psychiatric/psychological ones (since they are typical manifestations of stress, somatization, or psychosomatic illness), and that the environment where they work or live should be assessed in order to discover other factors at work that could explain the symptoms; and 4) lowering the safety limits for handset radiation (SAR levels) will not affect the situation.

[edit] Health hazards of base stations

Another area of worry about effects on the population's health have been the radiation emitted by base stations (the antennas on the surface which communicate with the phones), because, in contrast to mobile handsets, it is emitted continuously and is much more powerful. Due to the attenuation of power with the square of distance, field intensities drop rapidly with distance away from the base of the antenna. A 2002 survey study by Santini et al. found a variety of health effects for people living within 300 m of base stations. Fatigue, headache, sleep disruption and loss of memory were among the effects found.

As technology progresses and data demands have increased on the mobile network, the number of towers has increased sharply in many cities, and competing companies usually do not make an effort towards sharing towers. The latest trend is 3G towers, which work with higher bandwidths. The buildup of networks has sparked many health concerns and much community outrage. Examples of such can be seen from headlines around the world; locals pulling down base station masts, or even, in some countries, physically attacking installation crews, communities lobbying against the rollout of cell networks, protest banners, demonstrations near hospitals, houses and local schools.

Many measurements and experiments have shown, however, that transmitter power levels are relatively low - in modern 2G antennas, in the range of 20 to 100 watts. The ACMA (Australian Communications and Media Authority) and ARPANSA (Australian Radiation Protection and Nuclear Safety Agency) recently announced that the 3G towers actually cause less radiation than the already present 2G network. An average radiation power output of 3 watt is used. 'Micro-cell geometries' inside cities have decreased the amount of irradiated power even further. [citation needed]

The propagation of more towers may add to a more strongly irradiated area. However, it can result in lower radiation for the mobile phone user, since phones transmit at a lower power when closer to a base station. [8] [9]

Base stations create interference patterns or regions where their signals add (in phase) or cancel (out of phase). Base stations which are too closely located can also interfere with each other's operation, leading to competition between cell phone companies for sites.

There are few reliable, well conducted and long-range epidemiological studies published on the putative effects of base stations on health. For every positive report (such as the Santini study mentioned above), there are others reporting no effect at all.

ICNIRP STANDING COMMITEE ON EPIDEMIOLOGY, 2004 [10]: The report reviews the risks of cancer, cardiovascular disease, adverse outcomes of pregnancy and cataract formation associated with RF field exposure at work. It then reviews the risk of leukemia to populations who are closer to RF transmitters used in broadcasting and telecommunications and the risks of brain cancer and acoustic neuromas by mobile phone users. The report concludes that the research performed to date gives no consistent or convincing evidence of a causal relationship between RF field exposure and any adverse health effects.

IEE BIOLOGY EFFECTS POLICY ADVISORY GROUP, 2004 [11]: The report concludes that the research published during the previous two years do not suggest that harmful effects exist from exposure to low level RF fields. The results from 7 epidemiological studies failed to provide convincing evidence to suggest that the use of mobile phones increase the risk of brain cancer and acoustic neuromas. However, it did acknowledge that mobile phone base stations remained a cause of considerable public concern.

[edit] Occupational health hazards

Telecommunication workers who spend time at a short distance from the active equipment, for the purposes of testing, maintenance, installation, etc. may be at risk of much greater exposure than the general population. Many times base stations are not turned off during maintenance, because that would affect the network, so people work near "live" antennas.

In this way, excessive radiation levels may lead to adverse health effects, including severe acute burns or milder chronic alterations of the skin, and perhaps other non-thermal effects which have not yet been fully documented.

A variety of studies over the past 50 years have been done on workers exposed to high RF radiation levels: Studies including radar laboratory workers, military radar workers, electrical workers, amateur radio operators. Most of these studies found no increase in cancer rates over the general population or a control group. Many positive results could have been attributed to other work environment conditions, and many negative results of reduced cancer rates also occurred. [12]

[edit] Safety standards and licensing

In order to protect the population living around base stations and users of mobile handsets, governments and regulatory bodies adopt safety standards, which translate to limits on exposure levels below a certain value. There are many proposed national and international standards, but that of the International Committee for Non-Ionizing Radiation Protection (ICNIRP) is the most respected one, and has been adopted so far by more than 80 countries. For radio stations, ICNIRP proposes two safety levels: one for occupational exposure, another one for the general population. Currently there are efforts underway to harmonise the different standards in existence.

Radio base licensing procedures have been established in the majority of urban spaces regulated either at municipal/county, provincial/state or national level. Telcos are required to obtain construction licenses, provide certification of antenna emission levels and assure compliance to ICNIRP standards and/or to other environmental legislation. Posterior alterations in the level of emission, number of active antennas or technology standards used in an installed antenna array might require new licensing procedures.

Many governmental bodies also require that competing telcos try to achieve sharing of towers so as to decrease environmental and cosmetic impact. Regarding this issue, it is an influential factor of rejection of installation of new antennas and towers in communities. In some cases, camouflaging the towers like tree trunks and other more visually acceptable structures has been tried.

[edit] Lawsuits

In the USA, a small number of personal injury lawsuits have been filed by individuals against cellphone manufacturers, such as Motorola, NEC, Siemens and Nokia, on the basis of allegations of causation of brain cancer and death [13]. So far, most of these lawsuits have been dismissed by the courts, on lack of scientific evidence of such a causal relationship, and this has been reducing the motivation of tort lawyers to pursue these health injury lawsuits.

[edit] Precautionary principle

In 2000, the World Health Organization (WHO) recommended that the precautionary principle could be voluntarily adopted in this case (see WHO Electromagnetic Fields and Public Health Cautionary Policies). It follows the recommendations of the European Community for environmental risks. According to the WHO, the "precautionary principle" is "a risk management policy 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." Other less stringent recommended approaches are prudent avoidance principle and ALARA (As Low as Reasonably Achievable). Although all of these are problematic in application, due to the widespread use and economical importance of wireless telecommunication systems in modern civilization, there is an increased popularity of such measures in the general public. They involve recommendations such as the minimization of cellphone usage, the limitation of use by at-risk population (such as children), the adoption of cellphones and microcells with ALARA levels of radiation, the wider use of hands-off and earphone technologies such as Bluetooth headsets, the adoption of maximal standards of exposure, RF field intensity and distance of base stations antennas from human habitations, and so forth.

The WHO began the International EMF Project[5] to "fill in the gaps" of scientific research in this area. By May 2006, the project had concluded that base stations and wireless data networks had no adverse health effects, including cancer, sleep disturbances, or cardiovascular changes. Conclusions specific to mobile phones were expected in 2007 or 2008.[1]

[edit] See also

[edit] References

The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. Please see the relevant discussion on the talk page for further details.
  1. ^ a b http://www.who.int/mediacentre/factsheets/fs304/en/index.html
  2. ^ a b c "After 21 years, scientists say: mobiles don't cause cancer" by Mark Henderson. The Times (of London), 6 Dec. 2006. http://www.timesonline.co.uk/article/0,,13509-2488946,00.html
  3. ^ SWEDISH RADIATION PROTECTION AUTHORITY REPORT 2002 [1]: "No significant associations have been seen between all brain tumors combined and phone use, with relative risks ranging from 0,9 to 1,3 (...) Subgroup analyses showed no consistent pattern of increased risk. It was considered that it was not biologically plausible that exposure to RF fields could increase the risk of cancer. The studies conducted so far have ruled out with a reasonable certainty that mobile phones cause cancer."
  4. ^ WHO Workshop on Electromagnetic Hypersensitivy, Prague 2004.
  5. ^ http://www.who.int/peh-emf/en/
  • Repacholi, M.H. Health risks from the use of mobile phones. Toxicology Letters, 2000. available at [14] (PDF Format)
  • G J Hyland (2000). "Physics and biology of mobile telephony". The Lancet 356: 1833-1836.
  • Shaw CI, Kacmarek RM, Hampton RL, Riggi V, Masry AE, Cooper JB, Hurford WE. (2004). "Cellular phone interference with the operation of mechanical ventilators.". Crit Care Med. 32: 928-31.
  • Lawrentschuk N, Bolton DM. (2004). "Mobile phone interference with medical equipment and its clinical relevance: a systematic review.". Med J Aust. 181: 145-9.
  • Seitz, H, Stinner, D, Eikmann, Th, Herr, C, Roosli, M. Electromagnetic hypersensitivity (EHS) and subjective health complaints associated with electromagnetic fields of mobile phone communication -- a literature review published between 2000 and 2004. Science of the Total Environment, June 20 [e-publication ahead of print], 2005, available at http://www.sciencedirect.com.
  • Rubin, GJ, Das Munchi, J, Wessely, S. Electromagnetic hypersensitivity: a systematic review of provocation studies. Psychosom Med. Mar-Apr; 67(2): 224-32. 2005, available at [15].
  • K. R. Foster, The precautionary principle - common sense or environmental extremism? IEEE Technology and Society Magazine, 21:8-13 (2002).
  • Mobile Phones and Health 2004: Report by the Board of NRPB. Documents of the NRPB: Volume 15, No. 5 (In PDF)
  • Glaser, R. Are thermoreceptors responsible for "non-thermal" effects of RF fields? Edition Wissenschaft, 21, December 2005.
  • Sienkiewicz Z.J. and Kowalczuck, C.I. A Summary of Recent Reports on Mobile Phones and Health. NBRP Reports, 2004.

[edit] External links

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