|MadSci Network: Computer Science|
Brian, you ask:
I've heard studies suggest that wireless networks, and cell phones, have been shown to disturb brain function, increase tumors in the brain, and weaken the protective buffer between skull and brain. Is there scientific evidence to support this and is there evidence to refute these claims?
There are indeed "reports" that radio-frequency (RF) radiation from mobile phones and/or mobile base stations DO all of the things you mention. There are also numerous peer-reviewed studies that say they DO NOT.
These seemingly contradictory statements may be easier to understand when you realise that hundreds and hundreds of papers have been published on possible biological effects of RF radiation. I have nearly 700 such papers in my files. The IEEE International Committee on Electromagnetic Safety has compiled a list of 1743 such studies as part their updating of the IEEE C95.1 RF radiation safety guidelines.
When you have this many studies, you would expect to find numerous reports of "effects", since the laws of statistics dictate that some studies should find effects even if no such effects existed.
So the question you have to ask is:
Does RF radiation of the intensity produced by mobile phones, mobile phone base stations or wireless networks have any biological effects that have been confirmed and replicated?
Here the answer is a flat "NO".
Numerous scientific panels and government agencies have looked at this issue in recent years. Here is what some of them had to say:The U. S. Environmental Protection Agency
In a 1999 letter to the FCC, Robert Brenner (EPA Acting Deputy Assistant Administrator for Air and Radiation) stated:
A few studies report that at non-thermal levels, long term exposure to RF energy may have biological consequences. The majority of currently available studies suggests, however, that there are no significant non-thermal human health hazards. It therefore continues to be EPA's view that the FCC exposure guidelines adequately protect the public from all scientifically established harms that may result from RF energy fields generated by FCC licensees.An expert scientific panel in the United Kingdom
In 2000, a special committee in the U.K., the "Independent Expert Group on Mobile Phones" (also known as the "Stewart Commission") issued a report on mobile phone safety issues. On the general issue of radio-frequency radiation safety, the U.K. Independent Expert Group concluded that:
The balance of evidence to date suggests that exposures to RF radiation below NRPB and ICNIRP guidelines do not cause adverse health effects to the general population... There is now scientific evidence, however, which suggests that there may be biological effects occurring at exposures below these guidelines. This does not necessarily mean that these effects lead to disease or injury, but it is potentially important information...An expert scientific panel in Canada
An Expert Panel assembled by the Royal Society of Canada issued a report on mobile phone safety in 1999. The Expert Panel concluded:
Scientific studies performed to date suggest that exposure to low intensity non-thermal RF fields do not impair the health of humans or animals... It appears that exposure of the public to RF fields emitted from wireless telecommunications base transmitters is of sufficiently low intensity that biological or adverse health effects are not anticipated... It is possible that users of wireless telecommunication devices, including cell phones, may experience exposures of sufficient intensity to cause biological effects, although these biological effects are not known to be associated with adverse health effects... The level of evidence, and the limitations of the studies to date, do not support a conclusion that exposure to RF fields of the type and intensity produced by wireless telecommunication devices contributes to the development of tumours... Overall, these studies do not provide conclusive evidence of adverse health effects from RF exposure.Expert scientific panels in the United States
In 2001 the Institute of Electrical and Electronics Engineers (IEEE) published statements on mobile phones and mobile phone base stations.
On mobile phones they concluded that:
Several national and international organizations have established guidelines for human exposure to radio frequency energy. These include the IEEE C95.1 standard and the recommendations of the National Council on Radiation Protection and Measurements (NCRP) , the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the National Radiation Protection Board (NRPB) in the United Kingdom . While these guidelines differ in some respects, their limits in the frequency range used by wireless communications devices are broadly similar. The consensus of the scientific community, as reflected in these exposure guidelines, is that exposure to RF energy below recommended limits in these guidelines is safe.
Measurements have shown that RF exposure to individuals from use of cellular telephones and other low power wireless transceivers is normally within recommended limits. Some cell phones and other wireless transceivers can affect the operation of heart pacemakers, implantable defibrillators, or other body-mounted medical devices, if the phone is placed directly next to the devices (within a few centimeters). Individuals with such devices should follow their physicians? recommendations regarding safe use of wireless transceivers.
On base stations they concluded that:
In nearly all circumstances, public exposure to RF fields near wireless base stations is far below recommended safety limits... Consequently, wireless base stations are not considered to present a risk to the general population including aged people, pregnant women, and children
In a website (http://www.fda.gov/cellphones/) that went on-line in May 2002, the US Food and Drug Administration and the Federal Communications Commission concludes:
On mobile phone base stations:
The electromagnetic RF signals transmitted from base station antennas stations travel toward the horizon in relatively narrow paths... Therefore, RF exposure on the ground is much less than exposure very close to the antenna and in the path of the transmitted radio signal. In fact, ground-level exposure from such antennas is typically thousands of times less than the exposure levels recommended as safe by expert organizations. So exposure to nearby residents would be well within safety margins.
Measurements made near cellular and PCS base station antennas mounted on towers have confirmed that ground-level exposures are typically thousands of times less than the exposure limits adopted by the FCC. In fact, in order to be exposed to levels at or near the FCC limits for cellular or PCS frequencies an individual would essentially have to remain in the main transmitted radio signal (at the height of the antenna) and within a few feet from the antenna...
On mobile phone handsets:
The available scientific evidence does not show that any health problems are associated with using wireless phones. There is no proof, however, that wireless phones are absolutely safe... Whereas high levels of RF can produce health effects (by heating tissue), exposure to low level RF that does not produce heating effects causes no known adverse health effects. Many studies of low level RF exposures have not found any biological effects. Some studies have suggested that some biological effects may occur, but such findings have not been confirmed by additional research. In some cases, other researchers have had difficulty in reproducing those studies, or in determining the reasons for inconsistent results.An expert scientific panel in the Netherlands
In 2002, the Health Council of the Netherlands issued reports on the safety of mobile phones and mobile phone base stations. On the general issue of mobile phone safety, the Health Council concluded that:
The electromagnetic field of a mobile telephone does not constitute a health hazard, according to the present state of scientific knowledge.
With respect to mobile phone base stations, the Health Council reaffirmed their earlier (2000) conclusion that:
The chance of health problems occurring among persons living and working below bases stations as a result of exposure to electromagnetic fields originating from the antennas is, in the Committee's opinion, negligible. The field levels are always considerably below the exposure limits.An expert scientific panel in France
In 2001, the Directeur Général de la Santé issued a report on the safety of mobile phones and their base stations (Les Téléphones Mobiles, leurs Stations de Base et la Santé). On the general issue of mobile phone safety, the French report concluded that:
The risk of accident and fatality associated with the use of mobile telephones when driving has definitely been established. In the current state of knowledge, this is the only known health risk, albeit a very serious one.
With respect to mobile phone base stations, the report concluded that:
There is considerably less personal exposure in the vicinity of base stations (with the exception of exclusion areas) than there is when making a call with a mobile phone... In view of the exposure levels observed, the group of experts does not back the hypothesis that there is a health risk for populations living in the vicinity of base stations.An expert scientific panel in Australia
In a supplement to their 2002 RF radiation protection standard the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) wrote:
Radiofrequency radiation (RFR) from mobile phone towers makes only a minor contribution to the total environmental RFR that arises primarily from other communications sources...
Significant safety factors are incorporated into the exposure limits -- that is, the limits are set well below the level at which adverse health effects are known to occur. Current data does not establish the existence of adverse heath effects for exposure levels below the limits of the ARPANSA.Some on-line resources
Medical College of Wisconsin
Electromagnetic Fields, RF Radiation and Human Health
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