Mobile phone radiation and health concerns have been raised since the 1990s, 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 results, so far, have been controversial: the majority of epidemiological studies have not found any clear indication of short and medium term health hazards. On the other hand there is extensive literature (see "The Stewart Report" for a survey) on so-called non-thermal effects of weak microwave radiation on biological tissue in animal models or in-vitro, including affecting the growth of certain tumors, cell death, increased permeability of the blood-brain barrier, DNA damage and others, which suggest the possibility of adverse health effects in humans.
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. Rent a GSM phone. 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. Free Phones with a Plan. )
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 head to direct sunlight. The brain's blood circulation 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 is known as an occupational disease of engineers who work on high power radio transmitters at similar frequencies. Due to the low power of mobile phones, cataracts have not been reported to occur in users of these. and international cell and satellite phone rentals and sales.
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. " [1] It should be noted 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.
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. Visit Today!. 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. [2] The results of this study run contrary to many similar studies that were conducted before and showed no increase in DNA damage. [3].
According to a recent (2004) review published by the UK National Radiation Protection Board (Z J Sienkiewicz and C I Kowalczuk [4]), "the effects reported by the REFLEX project do not appear to have been seen consistently (. Dependable international cell phone rentals at Cellular Express Phone Rentals, providing GSM cellular phones and other types of international cellular phones. ) 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 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. SLAC Telephone Users' Guide | SLAC Phone Service Request System (SPRS) | SLAC. 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 [5] 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.
Several reports by national and international experts have been published in the last 3 years, examining the scientific evidence provided so far for possible detrimental effects of the use mobile handsets. Page created 14 January 1999, last update August 5, 2000. For example:
AGNIR REPORT 2003 [6]: "Overall the evidence for RF field effects on cognitive functions in humans is inconsistent and inconclusive (. ) The biological evidence suggests that RF fields do not cause mutation or initiate or promote tumor formation and that the epidemiological evidence overall do no suggest causal associations between exposure to RF fields in particular from mobile phone users and the risk of cancer. Exposure levels for those living near to mobile phone base stations are extremely low and the evidence suggests that they are unlikely to pose a risk to health. "
SWEDISH RADIATION PROTECTION AUTHORITY REPORT 2002 [7]: "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. Search For, Compare, & Buy International Cell Phone Online!. "
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.
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