Mobile phone cancer

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Mobile phone radiation and health

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). Mobile phones use electromagnetic radiation in the microwave range, and some believe this may be harmful to human health. 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, based upon the consensus view of the scientific and medical communities, states that health effects (e.g. headaches) are very unlikely to be caused by cellular phones or their base stations, and expects to make recommendations about mobile phones in October 2009.

However, some national radiation advisory authorities, including those of Austria, France, Germany, and Sweden recommended to their citizens measures to minimize exposure. Examples of the recommendations are:

Use hands-free to decrease the radiation to the head.
Keep the mobile phone away from the body.
Do not telephone in a car without an external antenna.

However, the use of "hands-free" was not recommended by the British Consumers' Association in a statement in November 2000 as they believed that exposure was increased. However, measurements for the (then) UK Department of Trade and Industry and others for the French l’Agence française de sécurité sanitaire environnementale showed substantial reductions. In 2005 Professor Lawrie Challis and others said clipping a ferrite bead onto hands-free kits stops the radio waves travelling up the wire and into the head.

Health hazards of handsets

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, can have a peak power of 2 watts, and a US analogue phone had a maximum transmit power of 3.6 watts. Other digital mobile technologies, such as CDMA2000 and D-AMPS, use lower output power, typically below 1 watt. The maximum power output from a mobile phone is regulated by the mobile phone standard it is following and by the regulatory agencies in each country. In most systems the cellphone and the base station check reception quality and signal strength and the power level is increased or decreased automatically, within a certain span, to accommodate for different situations such as inside or outside of buildings and vehicles.

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 the head. In Europe, the limit is 2 W/kg, averaged over a volume of 10 grams of tissue. 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. Thus, the European 10-gram ratings should be compared among themselves, and the American 1-gram ratings should only be compared among themselves. SAR data for specific mobile phones, along with other useful information, can be found directly on manufacturers' websites, as well as on third party web sites.

Thermal effects

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 will occur at the surface of the head, causing its temperature to increase by a fraction of a degree. In this case, 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 circulation is capable of disposing of excess heat by increasing local blood flow. However, the cornea of the eye does not have this temperature regulation mechanism and exposure of 2-3 hours' duration has been reported to produce cataracts in rabbits' eyes at SAR values from 100-140W/kg, which produced lenticular temperatures of 41°C. Premature cataracts have not been linked with cell phone use, possibly because of the lower power output of mobile phones.

Non-thermal effects

The communications protocols used by mobile phones often result in low-frequency pulsing of the carrier signal. Whether these modulations have biological significance has been subject to debate.

Some researchers have argued that so-called "non-thermal effects" could be reinterpreted as a normal cellular response to an increase in temperature. The German biophysicist Roland Glaser, for example, 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 caused 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.

Blood Brain Barrier effects

Swedish researchers from Lund University (Salford, Brun, Perrson, Eberhardt, and Malmgren) have studied the effects of microwave radiation on the rat brain. They found a leakage of albumin into the brain via a permeated blood-brain barrier. Other groups have not confirmed these findings in cell or animal studies.

Electromagnetic hypersensitivity

Some users of mobile handsets have reported feeling several unspecific symptoms during and after its use; ranging from 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), to disturbances of the digestive system. Reports have noted that all of these symptoms can also be attributed to stress and that current research cannot separate the symptoms from nocebo effects.

Genotoxic effects

Research published in 2004 by a team at the University of Athens had a reduction in reproductive capacity in fruit flies exposed to 6 minutes of 900 MHz pulsed radiation for five days. Subsequent research, again conducted on fruit flies, was published in 2007, with the same exposure pattern but conducted at both 900 MHz and 1800 MHz, and had similar changes in reproductive capacity with no significant difference between the two frequencies. Following additional tests published in a third article, the authors stated they thought their research suggested the changes were “…due to degeneration of large numbers of egg chambers after DNA fragmentation of their constituent cells …”.

In 1995, Lai and Singh reported damaged DNA after two hours of microwave radiation at levels deemed safe according to government standards in the journal Bioelectromagnetics. Later, in December 2004, a pan-European study named REFLEX (Risk Evaluation of Potential Environmental Hazards from Low Energy Electromagnetic Field (EMF) Exposure Using Sensitive in vitro Methods), 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, whole-sample average. 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.. Reviews of in vitro genotoxicity studies have generally concluded that RF is not genotoxic and that studies reporting positive effects had experimental deficiences.

Mobile phones and cancer

In 2006 a large Danish study about the connection between mobile phone use and cancer incidence was published. It followed over 420,000 Danish citizens for 20 years and showed no increased risk of cancer. The German Federal Office for Radiation Protection (BfS) consider this report as inconclusive.

In order to investigate the risk of cancer for the mobile phone user, a cooperative project between 13 countries has been launched called INTERPHONE The idea is that cancers need time to develop so only studies over 10 years are of interest.

The following studies of long time exposure have been published:

A Danish study (2004) that took place over 10 years and found no evidence to support a link.

A Swedish study (2005) that draws the conclusion that "the data do not support the hypothesis that mobile phone use is related to an increased risk of glioma or meningioma.

A British study (2005) that draws the conclusion that "The study suggests that there is no substantial risk of acoustic neuroma in the first decade after starting mobile phone use. However, an increase in risk after longer term use or after a longer lag period could not be ruled out.

A German study (2006) that states "In conclusion, no overall increased risk of glioma or meningioma was observed among these cellular phone users; however, for long-term cellular phone users, results need to be confirmed before firm conclusions can be drawn.

A joint study conducted in northern Europe that draws the conclusion that "Although our results overall do not indicate an increased risk of glioma in relation to mobile phone use, the possible risk in the most heavily exposed part of the brain with long-term use needs to be explored further before firm conclusions can be drawn.

Other studies on cancer and mobile phones are:

Tumour risk associated with use of cellular telephones or cordless desktop telephones, that states: "We found for all studied phone types an increased risk for brain tumours, mainly acoustic neuroma and malignant brain tumours".

A Swedish scientific team at the Karolinska Institute conducted an epidemiological study (2004) that suggested that regular use of a mobile phone over a decade or more was associated with an increased risk of acoustic neuroma, a type of benign brain tumor. The increase was not noted in those who had used phones for fewer than 10 years.

The INTERPHONE study group from Japan published the results of a study of brain tumour risk and mobile phone use. They used a new approach: determining the SAR inside a tumour by calculating the radiofrequency field absorption in the exact tumour location. Cases examined included glioma, meninigioma, and pituitary adenoma. They reported that the overall odds ratio (OR) was not increased and that there was no significant trend towards an increasing OR in relation to SAR-derived exposure.

In 2007, Dr. Lennart Hardell, from Örebro University in Sweden, reviewed published epidemiological papers (2 cohort studies and 16 case-control studies) and found that:

Cell phone users had an increased risk of malignant gliomas.
Link between cell phone use and a higher rate of acoustic neuromas.
Tumors are more likely to occur on the side of the head that the cell handset is used.
One hour of cell phone use per day significantly increases tumor risk after ten years or more.

In a February 2008 update on the status of the INTERPHONE study IARC stated that the long term findings ‘…could either be causal or artifactual, related to differential recall between cases and controls.’

A self-published and non-peer reviewed meta-study by Dr. Vini Khurana, an Australian neurosurgeon, presented an "increasing body of evidence ... for a link between mobile phone usage and certain brain tumours" and that it "is anticipated that this danger has far broader public health ramifications than asbestos and smoking". This was criticised as ‘…an unbalanced analysis of the literature, which is also selective in support of the author’s claims.’

Sleep and EEG effects

Some studies have claimed to show that mobile phone signals affect sleep patterns and possibly delay sleep onset during exposure. In another clinical study, carried out by Sweden's Karolinska Institute and Wayne State University in the US, the authors concluded their research suggested an association between RF exposure and adverse effects on sleep quality within certain sleep stages, though participants were unable to determine better than chance if they had been exposed to actual radiation or sham exposure. The UK National Health Service criticized the research because of the small sample size used, and because of the 53% of participants who reported sensitivity to mobile use, a proportion unlikely to be representative of the general population. The NHS also criticized the press for inaccurate reporting of the study.

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 more powerful at close quarters. On the other hand due to the attenuation of power with the square of distance, field intensities drop rapidly with distance away from the base of the antenna. Base station emissions must comply with ICNIRP guidelines of a maximum power density of 4.5 W/m² (450 microwatts/cm²) for 900 MHz and 9 W/m² (900 microwatts/cm²) for 1800 MHz. These guidelines are set for short term heating, which is the only understood mechanism of electromagnetic fields on biological tissue. The ICNIRP guidelines are distrusted by some. Several surveys have found increases of symptoms depending upon proximity to electromagnetic sources such as mobile phone base stations. A 2002 survey study by Santini et al. in France found a variety of self-reported symptoms for people who reported that they were living within of GSM cell towers in rural areas, or within of base stations in urban areas. Fatigue, headache, sleep disruption and loss of memory were among the symptoms reported. Similar results have been obtained with GSM cell towers in Spain, Egypt, Poland and Austria. It is, however, important to note that these surveys do not show statistically significant clustering or causality and those complaining of adverse symptoms may be displaying the nocebo effect, unless this is controlled in the study. There are significant challenges in conducting studies of populations near base stations, especially in assessment of individual exposure.

However, a study conducted at the University of Essex and another in Switzerland concluded that mobile phone masts were unlikely to be causing these short term effects in a group of volunteers who complained of such symptoms. The Essex study has been criticised as being skewed due to drop-outs of test subjects, although electrical sensitivity lobby groups have praised the study as a whole, and these criticisms were answered by the authors.

As technology progresses and data demands have increased on the mobile network, towns and cities have seen the number of towers increase sharply, including 3G towers which work with larger bandwidths. Many measurements and experiments have shown that transmitter power levels are relatively low - in modern 2G antennas, in the range of 20 to 100 W, with the 3G towers causing less radiation than the already present 2G network. An average radiation power output of 3 W is used. The use of 'micro-cell geometries' (large numbers of transmitters in an area but with each individual transmitter running very low power) inside cities has decreased the amount of radiated power even further. The radiation exposure from these antennas, while generally low level, is continuous.

Experts consulted by France consider it is mandatory that main antenna axis not to be directly in front of a living place at a distance shorter than 100 meters.. This recommendation was modified in 2003 to say that antennas located within a 100-metre radius of primary schools or childcare facilities should be better integrated into the cityscape and was not included in a 2005 expert report.

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.

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, and 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.

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 Commission 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. Mobile telephone service providers are, in many regions, required to obtain construction licenses, provide certification of antenna emission levels and assure compliance to ICNIRP standards and/or to other environmental legislation.

Many governmental bodies also require that competing telecommunication companies try to achieve sharing of towers so as to decrease environmental and cosmetic impact. This issue is an influential factor of rejection of installation of new antennas and towers in communities. The safety standards in the U.S. are set by the Federal Communications Commission (FCC). The FCC has based its standards primarily on those standards established by the Institute of Electronics and Electrical Engineering (IEEE), specifically Subcommittee 4 of the "International Committee on Electromagnetic Safety".

Evolution of Safety Standards

The following is a brief summary of the wireless safety standards, which have become stricter over time.

1966: The ANSI C95.1 standard adopted the standard of 10 mW/cm² (10,000 μW/cm²) based on thermal effects.
1982: The IEEE recommended further lowering this limit to 1 mW/cm² (1,000 μW/cm²) for certain frequencies in 1982, which became a standard ten years later in 1992 (see below).
1986: The NCRP recommended the exposure limit of 580 μW/cm².
1992: The ANSI/IEEE C95.1-1992 standard based on thermal effects used the 1 mW/cm² (1,000 μW/cm²) safety limit. The EPA called this revised standard "seriously flawed", partly for failing to consider non-thermal effects, and called for the FCC to adopt the 1986 NCRP standard which was five times stricter.
1996: The FCC updated to the standard of 580 μW/cm² over any 30-minute period for the 869 MHz, while still using 1mW/cm² (1,000 μW/cm²) for PCS frequencies (1850-1990 MHz).
1998: The ICNIRP standard uses the limit of 450 μW/cm².

Adequacy of Current Standards

The controversial question is whether the current safety standards are adequate enough to protect the public's long-term health. A few nations have set safety limits orders lower than the ICNIRP limit. In particular, the Salzburg Resolution for Austria recommends safety limits many times lower (0.6 V/m = 0.1 microWatts/cm² for pulsed radiation.

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. In US federal court, expert testimony relating to science must be first evaluated by a judge, in a Daubert hearing, to be relevant and valid before it is admissible as evidence. In one case against Motorola, the plaintiffs alleged that the use of wireless handheld telephones could cause brain cancer, and that the use of Motorola phones caused one plaintiff’s cancer. The judge ruled that no sufficiently reliable and relevant scientific evidence in support of either general or specific causation was proffered by the plaintiffs; accepted a motion to exclude the testimony of the plaintiffs’ experts; and denied a motion to exclude the testimony of the defendants' experts.

Precautionary principle

In 2000, the World Health Organization (WHO) recommended that the precautionary principle could be voluntarily adopted in this case. 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 economic importance of wireless telecommunication systems in modern civilization, there is an increased popularity of such measures in the general public, though also evidence that such approaches may increase concern. 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-free 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.