What
do recent reports from scientific meetings and journals say?
What
about the report that exposure of mice to cell phone radiation causes
damage to the DNA in their brain cells?Revisionsv2.6.3, Oct-2000:
v2.6.2, Sep-2000:
v2.6.0, Jul-2000:
v2.5.1, Apr-2000:
- Cross references to other questions are indicated by the letter Q followed
by the question number; for example, (Q9) indicates that
further information is found in Question 9.
- Technical references are shown in brackets; for example, [2]
is a reference to technical note 2.
- Technical notes follow the main FAQ.
- "International notes" are appended to regular
technical notes, so [International note 2] is a section within technical note 2.
1) Are there health hazards associated with living, working, playing, or going to school near a cellular phone or PCS base station antenna?
No. The consensus of the scientific community, both in the US and internationally, is that the power from these base station antennas is far too low to produce health hazards as long as people are kept away from direct access to the antennas (see Q13 and Q14 ).
It is critical to be aware of the difference between antennas, the objects that produce radio-frequency radiation; and towers or masts, the structures that the antennas are placed on. It is the antennas that people need to keep there distance from, not the towers that hold the antennas.
Not really. There are some reasons to be concerned about human health effects from the hand-held cellular and PCS phones themselves (although it is not certain that any risks to human health actually exist). These concerns exist because the antennas of these phones can deliver large amounts of radiofrequency energy to very small areas of the user's body [83]. Base station antennas do not create such "hot spots", so the potential safety issues concerning the phones have no real applicability to the base station antennas.
For further discussion of health issues related to hand-held phones see the ICNIRP report [1], the reviews by Moulder and colleagues [95, 131], the review by the Royal Society of Canada [99], and the report of the UK Independent Expert Group on Mobile Phones (the "Stewart Commission") [128]
No. There are many technical differences between cell phones, PCS phones, and the types of "cell" phones used in other counties [2, also see international note 2]; but for evaluation of possible health hazards, the only distinction that matters is that they operate at slightly different frequencies. The radiowaves from some base stations (e.g., those for the cell phones used in the U.S.) may be absorbed by humans somewhat more than the radiowaves from other types of base stations (e.g., those for the PCS phones used in the U.S.) [23]. However, once the energy is absorbed the effects are the same.
Yes and no. The radiowaves from some antennas (particularly FM and VHF-TV broadcast antennas) are absorbed more by humans than the radiowaves from other sources (such as cellular phone or PCS base station antennas); but once the energy is absorbed the effects are basically the same.
In addition, FM and TV antennas are 100 to 5000 times more powerful than base station antennas, but are mounted on much higher towers (typically 800 to 1200 ft).
Yes. Cellular and PCS phones and their base station antennas are radios, and produce radiofrequency (RF) radiation [3]; that's how they work. This radiofrequency radiation is "non-ionizing", and its biological effects are fundamentally different from the "ionizing" radiation produced by x-ray machines [see Q6].
No. The interaction of biological material with an electromagnetic source depends on the frequency of the source [4]. X-rays, radiowaves and "EMF" from power lines are all part of the electromagnetic spectrum, and the parts of the spectrum are characterized by their frequency. The frequency is the rate at which the electromagnetic field changes direction and is given in Hertz (Hz), where one Hz is one cycle (change in direction) per second, and 1 megahertz (MHz) is one million cycles per second.
Electric power in the US is at 60 Hz. AM radio has a frequency of around 1 MHz, FM radio has a frequency of around 100 MHz, microwave ovens have a frequency of 2450 MHz, and X-rays have frequencies above one million MHz. Cellular phones operate at 860-900 MHz, and PCS phones operate at 1800-2200 MHz [also see international note 2].
At the extremely high frequencies characteristic of X-rays, electromagnetic particles have sufficient energy to break chemical bonds (ionization). This is how X-rays damage the genetic material of cells, potentially leading to cancer or birth defects. At lower frequencies, such as radiowaves, the energy of the particles is much too low to break chemical bonds. Thus radiowaves are "non-ionizing". Because non-ionizing radiation cannot break chemical bonds, there is no similarity between the biological effects of ionizing radiation (x-rays) and nonionizing radiation (radiowaves) [4].
The Electromagnetic Spectrum |
 |
No. Power lines produce no significant non-ionizing radiation, they produce electric and magnetic fields. In contrast to non-ionizing radiation, these fields do not radiate energy into space, and they cease to exist when power is turned off. It is not clear how, or even whether, power line fields produce biological effects; but if they do, it is not in the same way that high power radiowaves produce biological effects [4, 53]. There appears to be no similarity between the biological effects of power line "EMF" and the biological effects of radiowaves.
Yes. There are national and international safety guidelines for exposure of the public to the radiowaves produced by cellular phone and PCS base station antennas. The most widely accepted standards are those developed by the Institute of Electrical and Electronics Engineers and American National Standards Institute (ANSI/IEEE) [5], the International Commission on Non-Ionizing Radiation Protection (ICNIRP) [6], and the National Council on Radiation Protection and Measurements (NCRP) [7].
These radiofrequency standards are expressed in "plane wave power density", which is measured in mW/cm-sq (milliwatts per square centimeter) [8]. For PCS (1800-2000 MHz) antennas, the 1992 ANSI/IEEE exposure standard for the general public is 1.2 mW/cm-sq. For analog cellular phones (about 900 MHz), the ANSI/IEEE exposure standard for the general public is 0.57 mW/cm-sq [9]. The ICNIRP standards are slightly lower and the NCRP standards are essentially identical [10].
In 1996 the U.S. Federal Communications Commission (FCC) released radiofrequency guidelines for the frequencies and devices they regulate, including cellular phone and PCS base station antennas [11]. The FCC standards for cellular phone and PCS base station antennas are essentially identical to the ANSI/IEEE standard [5].
The public exposure standards apply to power densities averaged over relatively short periods to time, 30 minutes in the case of the ANSI/IEEE, NCRP, and FCC standards (at PCS and cellular phone frequencies). Where there are multiple antennas, these standards apply to the total power produced by all antennas [13].
Yes. When scientists examined all the published literature on the
biological effects of radiowaves they found that the literature agreed on a
number of key points [see 1, 5, 6,
7, 14, 53, 83,
90, 95, 96 and 99
for details]:
ANSI/IEEE and FCC applied a 10-fold safety margin to establish occupational exposure guidelines. They then applied an additional 5-fold safety margin for continuous exposure of the general public. Finally, detailed studies were done to establish the relationship of power density, which can be routinely measured, to energy absorption, which really matters [8].
The result was a highly conservative public exposure guideline that was set at a level that is only 2% of the level where replicated biological effects have actually been observed.
No. There are differences between the standards. ANSI/IEEE, ICNIRP, NCRP and FCC all use the same biomedical data, and the same general approach to setting safety guidelines. However, there are differences in the models used by the different groups, and hence there are slight differences in the final numbers [17]. No biological significance should be associated with these slight differences.
A number of countries have their own regulations for public exposure to RF radiation from mobile phone base station antennas. While most of these regulation follow the same patterns and rationales used by ANSI/IEEE [5] and ICNIRP [6], they do differ. See note 12 for details.
Yes. Until 1996 the U. S. Federal Communication Commission (FCC) used an out-dated (1982) ANSI standard that was really designed for occupational, rather than public exposure. In 1996 the FCC adopted a new standard that is based on the newer (1992) ANSI standard, but which is not identical to it [11].
The new FCC standard for mobile phone base stations is 0.57 mW/cm-sq for cellular phone frequencies and 1.0 mW/cm-sq for PCS phone frequencies. This 1996 FCC standard applied to all new transmitters licensed after 15-Oct-97, but pre-existing facilities had until 1-Sep-2000 to demonstrate compliance.
The FCC power-density standards described above apply to whole-body public exposure to radio-frequency radiation from mobile phone base stations; they do not apply to exposure from the phones themselves or to occupational exposure. For a discussion of exposure from the phones or a discussion of occupational RF radiation exposure see FCC OET Bulletin 56 [135], the FCC guideline itself [11], and Foster and Moulder [131].
Yes. With proper design, cellular phone and PCS base station antennas can meet all safety standards by a wide margin.
A low-gain base station antenna, mounted 10 meters (30 ft) off the ground and operated at the maximum possible intensity, might produce a power density as high as 0.01 mW/cm-sq on the ground near the antenna site; but ground level power densities will more often be in the 0.00001 to 0.0005 mW/cm-sq range [57, 77, 123, 130]. These power densities are far below all the safety standards, and the standards themselves are set far below the level where potentially hazardous effects have been seen.
Within about 200 meters (600 ft) of the base of the antenna site, the power density may be greater at elevations above the base of the antenna site (for example, at the second floor of a building or on a hill). Even with multiple antennas, and with both cellular phone and PCS antennas on the same tower, power densities will be less than 2% of the guidelines at all heights and at all distances of more than 60 meters (180 ft) from an antenna site.
Further than about 200 meters (600 ft) from the antenna site power density does not rise with increased elevation.
Power density inside a building will be lower by a factor of 3 to 20 than outside [54,130].
Peterson et al [77] measured power densities around cell phone base stations. The measurements were for 1600 W (ERP) low-gain antennas (see Q14H for a discussion of antenna power and gain) on towers that ranged from 40 to 83 meters (120 to 250 ft) in height. The maximum power density on the ground was 0.002 mW/cm-sq, and the maximum was at 20 to 80 meters (60-240 feet) from the base of the towers. Within 100 meters (300) feet of the base of the towers, the average power density was less than 0.001 mW/cm-sq. These maximum RF power densities are all less than 1% of the FCC, ANSI/IEEE, NRPB and ICNIRP standards for public exposure.
In 1999 in Vancouver Canada, Thansandote et al [123] measured RF levels in five schools, three of which had base stations on them or near them. All schools met Canadian, US and international RF standards by a wide margin. The maximum readings are shown in the following table.
| School
| Base Station Location | Maximum RF Level |
| 1 | PCS base station across street | 0.00016 mW/cm-sq |
| 2 | analog base station on roof | 0.0026 mW/cm-sq |
| 3 | analog base station across street | 0.00022 mW/cm-sq |
| 4 and 5 | no antennas nearby | less than 0.00001 mW/cm-sq |
| Canadian Standard | less than 0.57 mW/cm-sq |
In 2000, the U.K. National Radiation Protection Board [130] measured radiofrequency radiation levels at 118 publicly-accessible sites around 17 cell phone base stations. The maximum exposure at any location was 0.00083 mW/cm-sq (on a playing field 60 meters from a school building with an antenna on its roof). Typical power densities were less than 0.0001 mW/cm-sq (less than 0.01% of the ICNIRP public exposure guidelines). Power densities indoors were substantially less than power densities outdoors. When radiofrequency radiation from all sources (cell phone, FM radio, TV, etc.) was taken into account the maximum power density at any site was less than 0.2% of the ICNIRP public exposure guidelines. Details are shown in the following figure.
Radiofrequency Radiation Levels Near Mobile Phone Base Stations in the UK |
 |
| The relationship between the RF power density and distance from the base of the tower or building on which the mobile phone base antenna was located. Adapted from Mann et al. [130]. |
The relationship between the RF levels required to produce known biological effects, the RF levels specified in the FCC safety guidelines, and the RF levels found around mobile phone base stations is shown in the following figure.
Standards for Mobile Phone Base Stations |
 |
| The relationship between the RF power density level required to produce known biological effects, the RF power density levels specified in the FCC safety guidelines, and the RF power density levels found around mobile phone base stations. Because the RF power density required to produce biological effects is dependent on frequency, this figure only applies to frequencies between 800 and 2200 MHz (that is, those currently used by analog and digital cellular phones). |
Yes. There are some circumstances under which an improperly designed cellular phone and PCS base station antenna could violate safety standards.
Safety standards for uncontrolled (public) exposure could be violated if antennas were mounted in such a way that the public could gain access to areas within 20 feet (horizontal) of the antennas themselves [18]. This could arise for antennas mounted on, or near, the roofs of buildings. For antennas mounted on towers, it is very difficult to imagine a situation that would not meet the safety standards.
Safety standards for controlled (occupational) exposure could be violated if antennas were mounted on a structure where worker access to areas within 10 feet the antennas is required [18]. Peterson et al [77], for example, found that 2-3 feet from a 1600 W (ERP) low-gain roof-top antenna, the power density was as high as 2 mW/cm-sq (compared to the ANSI [9] public exposure standard of 1.2 to 0.57 mW/cm-sq).
While specific recommendations require a detailed knowledge of the site, the antenna, and the mounting structure, some general criteria can be set.
The FCC guidelines [11] require detailed calculations and/or measurement of radiofrequency radiation for some high-power rooftop transmitters, and some high-power transmitters whose antennas are mounted on low towers [19].
In general, the above guidelines will always be met when antennas are placed
on their own towers. Problems, when they exist, are generally confined to:
Because siting criteria for high- and low-gain antennas are different it is important to be able to tell them apart (see Q14H for a discussion of antenna gain). Fortunately, the antennas look rather different:
Distinguish the Two Antenna Types |
 |
Even from a distance the site (towers) for high- and low-gain antennas look different. When high-gain antennas are mounted on buildings, they may not be obvious, particularly if they are mounted to the sides of building, or more commonly to the sides of penthouses.
Different Ways to Mount Antennas |
 |
The RF patterns for the two different types of antennas are very different. For a low-gain (whip) antenna with a typical 1000 W ERP (see Q14H for a discussion of antenna power and gain) of the type used by most cell phone bases stations, the pattern looks like this:
RF Emissions from a 1000 W ERP Low-Gain
Antenna
|
 |
Very close to a low-gain antenna (in what is technically known as the "near field"), the power density around an antenna looks like this:
RF Emissions from a 1000 W ERP Low-Gain
Antenna
|
 |
The data for the above figure were adapted (with permission) from drawings provided by UniSite Inc. of Tampa, Florida (http://www.unisite.com).
For a high-gain (sector) antenna of the type used in PCS base stations, the pattern looks like this:
RF Emissions from a Single 1000 W ERP
High-Gain Antenna
|
 |
Keep in mind that a typical PCS base station will use 3 (or occasionally 4) of these transmission antennas, all pointing in different directions.
Very close to a single high-gain antenna (in what is technically known as the "near field"), the power density around an antenna looks like this:
RF Emissions from a Single 1000 W ERP
High-Gain Antenna
|
 |
The data for the above figure were adapted (with permission) from drawings provided by UniSite Inc. of Tampa, Florida (http://www.unisite.com).
In general this will not be a problem.
No. Radiofrequency safety guidelines do not require either setbacks or use restrictions around cellular or PCS base station antenna sites, since power levels on the ground are never high enough to exceed the guidelines for continuous public exposure (see Q8 and Q12).
As discussed in Q13 and Q14, there may be circumstances where use restrictions will have to be placed around the antennas themselves.
A detailed discussion of radio-frequency radiation occupational safety guidelines is beyond the scope of this FAQ.
In a detailed discussion of guidelines for telecommunications antenna installation, Tell [116] makes the following recommendations:
Specific Antenna Installation Guidelines (from Tell [116])
Work Practices for Reducing Radio-frequency Radiation Exposure (from Tell [116])
Compliance can be assessed through measurements or calculations. Both methods require a solid understanding of the physics of RF radiation, and measurements require access to sophisticated and expensive equipment.
Calculation: If the effective radiated power (ERP) and antenna gain of the base station antenna is known (see Q14H for a discussion of ERP and gain) and the height of the antenna is known, then "worst case" calculations of ground level power density can be made. However, the calculation method is not simple and the ERP is often unknown (height and antenna gain can be estimated by visual inspection of a site).
Measurement : Actual measurement of power density from mobile phone base stations requires sophisticated and expensive equipment and considerable technical knowledge. The instruments designed to measure power line fields and the instruments designed to test microwave ovens are not suitable for measuring base stations. Determining that base stations meet ANSI/IEEE, FCC, NRPB is ICNIRP standards is "relatively easy", but the instruments required cost well over US$$ 2000. Actual measurement of the power-density from a base station antenna is much more difficult, as there are many other sources of RF radiation at a typical site (see Mann et al [130]).
For a technical discussion of measurement techniques and instrumentation see Mann et al [130] and NCRP Report No. 119 [134].
The power of a mobile phone base station is usually described by its effective radiated power (ERP) which is given in watts (W). Alternatively, the power can be given as transmitter power (in watts) and the antenna gain.
Transmitter power is a measure of total power, while ERP is a measure of the power in the main beam. If an antenna was omni-directional and 100% efficient, then transmitter power and ERP would be the same. But mobile phone base station antennas (like most antennas) are not omni-directional; they are moderately (low-gain antennas) to highly (high-gain antennas) directional. The fact that they are directional means that they concentrate their power in some directions, and give out much less power in other directions.
Antenna gain is a measure of how directional an antenna is; it is measured in decibels (dB). For example, a 30 W transmitter with a 15 dB antenna (reasonably typical for a sectored mobile phone base station) would have an ERP of 950 W.
Perhaps the concept of "gain" and "ERP" are best explained by analogy to light bulbs. Compare a regular 100 W light bulb and a 100 W spot light. Both have the same total power, but the spot light is much brighter when you are in its beam and very weaker when you are outside its main beam. A mobile phone base antenna (particularly a high-gain panel antenna) is like the spot light, and ERP is equivalent to the power in the spot light's main beam.
For a more complete technical discussion of these issues see Section 2.2.11 of NCRP Report No. 119 [134].
Not everyone. Even among scientists there are a few people who claim that there is evidence that low level exposure to RF is hazardous (see, for example, Q15B and Q15C). However, even these scientists generally do not argue that power densities as low as those found around properly-designed base station antenna sites are hazardous.
Yes. The EPA asked the FCC to adopt parts of the 1986 NCRP guidelines [7] rather than the entire 1992 ANSI guidelines [5]. This the FCC did [11], and EPA has formally endorsed the FCC safety standards.
In a 25-Jul-96 letter to Reed Hunt (Chairman of the FCC), Carol Browner (Director of EPA) wrote:
"We have reviewed... 'FCC Draft of July 2, 1996, in the Matter of Guidelines for Evaluating The Environmental Effects of Radiofrequency Radiation'. This new approach... addresses our concerns about adequate protection of public health. I commend you for taking this approach..."
In a 17-Jan-97 follow-up letter to Reed Hunt (Chairman of the FCC), Mary Nichols (EPA Assistant Administrator for Air and Radiation) wrote:
"I would like to reiterate EPA's support of FCC's final RF exposure guidelines issued in August [of 1996] as providing adequate protection of public health."
In a 30-April-1999 letter to the FCC, Robert Brenner (EPA Acting Deputy Assistant Administrator for Air and Radiation) stated:
"The FCC guidelines expressly take into account thermal effects of RF energy, but do not directly address postulated non-thermal effects, such as those due to chronic exposure. That is the case largely because of the paucity of scientific research on chronic, non-thermal health effects. The information base on non-thermal health effects has not changed significantly since the EPA's original comments in 1993 and 1996. 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."
Yes and no. That claim was made in 1996, but follow-up studies in Australia (see below) and in the UK (see Q15D) contradict this claim.
Hocking and colleagues [28] published an "ecological" epidemiology study that compares municipalities "near TV towers" to those further away. No RF exposures were actually measured, but the authors calculate that exposures in the municipalities "near TV towers" were 0.0002 to 0.008 mW/cm-sq. No other sources of exposure to RF are taken into account, and the study is based on only a single metropolitan area. The authors report an elevated incidence of total leukemia and childhood leukemia, but no increase in total brain tumor incidence or childhood brain tumor incidence.
More detailed epidemiology studies of FM/TV antennas in the U.K. have not found evidence for a cancer connection (see Q15D).
In 1998, McKenzie and colleagues [62] repeated the Hocking study [28]. McKenzie and colleagues looked at the same area, and at the same time period; but they made more precise estimates of the RF exposure that people got in various areas. They found increased childhood leukemia in one area near the TV antennas, but not in other similar areas near the same TV antennas; and they found no significant correlation between RF exposure and the rate of childhood leukemia. They also found that much of the "excess childhood leukemia" reported by Hocking et al occurred before high-power 24-hour TV broadcasting had started. This replication study, plus the failure to find any effect in the larger UK studies (see Q15D), suggests that correlation reported by Hocking et al [28] was an artifact.
Yes. In a 1995 article labeled an "opinion piece", Goldsmith [29A] argues that there is evidence that RF exposure is associated with mutations, birth defect, and cancer. This review is based largely on what the author admits to be "non-peer-reviewed sources", most of which are stated to be "incomplete" and to lack "reliable dose estimates". The author further states that "no systematic effort to include negative reports is made; thus this review has a positive reporting bias".
In an article based on a 1996 meeting presentation [29B]
Goldsmith argues that epidemiological studies "suggest that RF exposures
are potentially carcinogenic and have other health effects". His
conclusions are based largely on:
- studies of RF exposure at the US embassy in Moscow (see Q16
and Hill [68]);
- the "geographical correlation" studies of Hocking et al [28]
and Dolk et al [34, 35] that are discussed in Q15B
and Q15D;
- the study of Korean war radar operators by Robinette et al [67]
that is discussed in Q16.
Few scientists agree with the opinions expressed by Goldsmith (see, for examples the reviews of the RF epidemiology in 1, 5, 6, 7, 14, 53); and even fewer would be willing to base a conclusion on the types of data sources that Goldsmith relies on.
Yes and no. Dolk and colleagues [34] investigated a reported leukemia and lymphoma cluster near a high-power FM/TV broadcast antenna at Sutton Coldfield in the UK. They found that the incidence of adult leukemia and skin cancer was elevated within 2 km of the antenna, and that the incidence of these cancers decreased with distance. No associations at all were seen for brain cancer, male or female breast cancer, lymphoma or any other type of cancer.
Because of this finding, Dolk and colleagues [35] extended their study to 20 other high-power FM/TV broadcast antennas in the UK. Cancers examined were adult leukemia, skin melanoma and bladder cancer, and childhood leukemia and brain cancer. No elevations of cancer incidence were found near the antennas, and no declines in cancer incidence with distance were seen. This large study does not support the results found in the much smaller studies by the same authors at Sutton Coldfield [34] or by Hocking et al [28] in Australia.
Yes and no. Roger Coghill (U.K.) and Neil Cherry (New Zealand) have been quoted in the mass media as claiming that there is evidence that RF exposure is hazardous at intensities well below the ANSI, FCC, ICNIRP and NRPB guidelines.
Roger Coghill appears to be an "environmental manager", who runs a laboratory that makes [permanent?] magnets "to help people suffering from muscular or arthritic pain" [59]. He has self-published a document [58] that explains "Coghill's hypothesis of cerebral morphogenic radiation". Apparently, Coghill believes that "the brain is actually a organic fully operational radio transmission station... that is in radio contact with every cell in its body" [59]. He appears to base his theory heavily on "Eastern European" research that has not been published in the West [59].
Neil Cherry is an elected official from New Zealand. and a "Senior Lecturer in Agricultural Meteorology" [60]. Like Coghill, he has self-published a document on the hazards of exposure to low-intensity RF [60]. Cherry has been quoted in the mass media as saying that "EMF exposure" is "highly statistically associated with health effects although there is no scientific proof that EMF caused the health effects" [61]. According to Cherry, these health effects include "cancer at many sites in the body, sleep disruption, chronic fatigue syndrome, miscarriage, birth defects, altered human EEG and circadian rhythms and several other adverse effects." [61]. Cherry's ideas appear to depend heavily on the views of Goldsmith (Q15C) and Hocking (Q15B).
Neither Coghill nor Cherry have published anything in the peer-reviewed scientific literature to support their claims. Both Coghill and Cherry mix discussions of power-frequency fields and RF as though they were biologically equivalent (which is almost certainly not correct), and to rely heavily on unpublished and non-reviewed sources (which are impossible to check). Their comments to the mass media have been very vague as to the scientific basis for their opinions. Until Coghill and Cherry present their theories in a peer-reviewed scientific forum, and back their theories with actual data, it is impossible for any scientist to take their theories seriously.
Yes and no. Dr. Henry Lai (Department of Bioengineering, University of Washington, Seattle) has claimed at meetings that "low intensity" RF radiation has effects on the nervous system of rats. Dr. Lai has further claimed at meetings that there are published studies showing that RF radiation can produce "health effects" at "very low field" intensities.
Dr. Lai's own research has no obvious relevance to the safety of cell phone base stations since most of his studies were conducted with RF radiation intensities far above those that would be encountered near base stations. In general, Dr. Lai's studies were done with at a power density of 1 mW/cm-sq and an SAR of 0.6 W/kg [31, 92, 93]. This RF radiation intensity is over 100 times greater than that would be encountered in publicly-accessible areas near FCC-compliant base stations [16], and substantially exceeds the SAR limit that forms the basis of the FCC [11] and ANSI [5] safety guidelines for public exposure [17]. For further discussion of the research on possible effects of RF radiation on the nervous system see reviews by Lai [93] and Juutilainen and de Seze [90].
At a meeting in Vienna in 1998, and in a letter sent to public officials in 1999, Dr. Lai referenced six studies in support of his claim that there is data showing that RF radiation can produce "health effects" at "very low field" intensities. These studies were:
There appears to be no real basis for these claims.
In the summer and fall of 1999 (and repeated in the Spring of 2000), programs on British, American and French TV claimed that there was new data suggesting that RF radiation from cell phones could cause injury to humans. Four sources of "new" information were generally cited:
The last two of these "new" studies were only vaguely described in the TV reports, but they appear to be references to studies sponsored by the mobile phone industry in the US (under the program called WTR). The biology study was presented at a meeting in March, 1999 and published abstracts are available [102, 103]. The epidemiology study was presented at a meeting in June 1999, but there is not even a published abstract.
The U.S. Food and Drug Administrations (FDA) appears to have seen the studies, and published the following comments of 20-Oct-99 [for full text see http://www.fda.gov/cdrh/ocd/mobilphone.html].
"Researchers conducted a large battery of laboratory tests to assess the effects of exposure to mobile phone RF on genetic material. These included tests for several kinds of abnormalities, including mutations, chromosomal aberrations, DNA strand breaks, and structural changes in the genetic material of blood cells called lymphocytes. None of the tests showed any effect of the RF except for the micronucleus assay, which detects structural effects on the genetic material. The cells in this assay showed changes after exposure to simulated cell phone radiation, but only after 24 hours of exposure. It is possible that exposing the test cells to radiation for this long resulted in heating. Since this assay is known to be sensitive to heating, heat alone could have caused the abnormalities to occur. The data already in the literature on the response of the micronucleus assay to RF are conflicting. Thus, follow-up research is necessary. [Tice et al. Tests of mobile phone signals for activity in genotoxicity and other laboratory assays. In: Annual Meeting of the Environmental Mutagen Society; 29 March 1999, Washington, D.C.; and personal communication, unpublished results.]."
"In a hospital-based, case-control study, researchers looked for an association between mobile phone use and either glioma (a type of brain cancer) or acoustic neuroma (a benign tumor of the nerve sheath). No statistically significant association was found between mobile phone use and acoustic neuroma. There was also no association between mobile phone use and gliomas when all types of types of gliomas were considered together. It should be noted that the average length of mobile phone exposure in this study was less than three years. When 20 types of glioma were considered separately, however, an association was found between mobile phone use and one rare type of glioma, neuroepithelliomatous tumors. It is possible with multiple comparisons of the same sample that this association occurred by chance. Moreover, the risk did not increase with how often the mobile phone was used, or the length of the calls. In fact, the risk actually decreased with cumulative hours of mobile phone use. Most cancer causing agents increase risk with increased exposure. An ongoing study of brain cancers by the National Cancer Institute is expected to bear on the accuracy and repeatability of these results. [Muscat et al. Epidemiological Study of Cellular Telephone Use and Malignant Brain Tumors. In: State of the Science Symposium;20 June 1999; Long Beach, California. ]"
Oddly, the FDA's description of the work of Tice and colleagues does not completely match their published abstracts [102, 103]. The abstracts state that five different genotoxicity tests were done at SARs of 1, 2.5, 5 and 10 W/kg with both a 837 MHz analog signal and a 1900 MHz digital signal; and that none of the tests showed increased DNA damage, increased micronucleus frequency, increased mutations or increased chromosome damage.
In May 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 [128]. The full text is available at: http://www.iegmp.org.uk/IEGMPtxt.htm.
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 [14] and ICNIRP [6] guidelines do not cause adverse health effects to the general population." [Section 1.17]
"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..." [Section 1.18]This "new scientific information" the Stewart Commission refers to is largely the reaction time studies of Preece et al [97] and Koivisto et al [117] that are discussed in Q19C, and studies by dePomerai et al [127] which suggest that nonthermal exposures of nematode worms can lead to expression of heat shock proteins.
With respect to mobile phone base stations, the U.K. Independent Expert Group concluded that:
"The balance of evidence indicates that there is no general risk to the health of people living near to base stations on the basis that exposures are expected to be small fractions of guidelines." [Section 1.33]However, the U.K. Independent Expert Group was quite critical of the planning process used for siting base stations in the U.K., and recommended that:
"...the siting of all new base stations should be subject to the normal planning process." [Section 1.36]
"...protocols be developed, in concert with industry and consumers, which can be used to inform the planning process and which must be assiduously and openly followed before permission is given for the siting of a new base station." [Section 1.37]
"[the protocols should include] a requirement for public involvement, an input by health authorities/health boards and a clear and open system of documentation which can be readily inspected by the general public." [Section 1.38]
"...an independent random, ongoing, audit of all base stations be carried out to ensure that exposure guidelines are not exceeded outside the marked exclusion zone... and that particular attention should be paid initially to the auditing of base stations near to schools..." [Sections 1.40 and 1.41].Specifically with respect to schools, the U.K. Independent Expert Group also recommended that:
"...[for] base stations sited within school grounds, that the beam of greatest intensity should not fall on any part of the school grounds or buildings without agreement from the school and parents. Similar considerations should apply to base stations sited near to school grounds." [Section 1.42].
Probably the most controversial recommendations made by the U.K. Independent Expert Group referred to the phones themselves rather than base stations, when they recommended that:
"...drivers be dissuaded from using either hand-held or hands-free phones while on the move." [Section 1.22]and that:
"...the widespread use of mobile phones by children for non-essential calls should be discouraged and... that the mobile phone industry should refrain from promoting the use of mobile phones by children." [Section 1.53].
The recommendation that children be discouraged from using phones is based
largely on the cognitive effect studies of Preece et al [97]
and Koivisto et al [117] and on the European Union
"Precautionary Principle" [129].
This recommendation has been criticized on multiple grounds:
Yes and no. While there have been no epidemiology studies of cancer and cell phone base stations, there have been epidemiology studies of cancer and other types of exposure to radiowaves. For a recent review see Elwood [94].
In general, epidemiology studies of radiowaves and cancer have not found
significant correlations between exposure and cancer. The studies include:
- studies of cancer in people occupationally exposed to radiowaves,
- geographic correlation studies that compare cancer rates among areas with
different potential exposures to radiowaves,
- "cancer cluster" studies.
Geographic correlation studies (see Q15B, Q15D and Elwood [94]) estimate the strength of radiowaves in geographic areas and correlate these estimates with disease rates in these areas. Even when the design of geographic correlation studies is optimal, they are considered exploratory and are not used for determining causality.
Reports of clusters of cancer provide little practical information. The major
steps in evaluating reports of "cancer clusters" are:
- define a logical (as opposed to arbitrary) boundary in space and time,
- determine whether an excess of a specific type of cancer has actually
occurred,
- identify common exposures and characteristics.
The above steps, however, have not generally been followed in studies of
radiowaves, and reports of "cancer clusters" are of essentially no
value in determining whether exposure to radiowaves is a cause of cancer (see
Elwood [94] for details of these studies).
The majority of the occupational studies of radiowaves exposure have deficiencies in exposure assessments because occupation or job title was used as an estimate of exposure; that is, actual radiowave exposure levels are not known.
There are four epidemiological studies that are generally considered to have acceptable design and analysis, adequate sample size, and sufficient follow-up time: Robinette et al [67], Hill [68], Milham [69, and Morgan et al [118]]. These four studies do not show statistically-significant associations between exposure to radio-frequency radiation and either cancer in general or any specific kind of cancer.
The other studies of acceptable design (Lilienfeld et al [70], Lagorio et al [71], Muhm [72], Tynes et al [73], Grayson et al [33], Thomas et al [105], and Dreyer et al [122]) have more limitations in exposure assessment, case ascertainment, or follow-up time; but they also do not suggest that radiowave exposure increases the risk of either cancer in general or any specific kind of cancer.
Szmigielski [79] studied Polish military personnel who may have had radiowave exposure. The incidence of cancer of all types, brain cancer, leukemia and lymphoma are reported to be elevated in exposed personnel. Because the methods of data collection and analysis are inadequately described or unsuitable, and because assessment of radiowave exposure is very deficient, the report does not meet basic epidemiological criteria for acceptability. Elwood [94] also concludes that the methods used in the Szmigielski study may have created a systematic bias "that would be expected to produce an increased relative risk for all types of cancer".
In 1996, Rothman et al. [121] published a study that reviewed health records of more than 250,000 mobile phone users. They found no difference in mortality between the users of hand-held portable phones (where the antenna is placed close to the head) and mobile cellular phones (where the antenna is mounted on the vehicle). In a 1999 follow-up study [122], the same group examined specific causes of death among nearly 300,000 mobile phone users in several U.S. cities. The investigators found no difference in overall cancer rates, leukemia rates, or brain cancer rates between the users of hand-held portable phones and the users of mobile cellular phones. The only specific cause of death that correlated with mobile phone use was deaths from motor vehicle collisions.
To date, only one case-control study has evaluated cancer in mobile phone users. Hardell et al. [100A, 100B] conducted a study of brain tumors in Swedish mobile phone users, as part of a larger study of possible causes of brain cancer (other possible causes evaluated included occupation, radiation therapy for cancer, exposure to diagnostic radiation, and exposure to a wide variety of chemicals). Exposure was assessed by questionnaires, and analyses were based on use of hand-held cellular telephones (use of "hands-free" devices and use in a car with a fixed antenna were not considered to be "exposure"). No elevation of brain tumor incidence was found in users of either digital or analog phones, and no exposure-response trend was observed (see figure below). When analysis was restricted to temporal, occipital and temporoparietal tumors on the same side of the brain where the cell phone was reported to have been used, a non-significant excess incidence was found. This increase was seen for use of analog phones, but not for the use of digital phones [100A].
Brain Cancer in Cell Phone Users |
 |
| Relative risk of brain cancer (odds ratio with 95% confidence interval) in users of hand-held cell phones from the epidemiological study of Hardell et al [79]. The number of cases in the overall analysis, and the sub-analyses are shown in parentheses. The analog phones are either at 450 (NMT 450) or 900 MHz; the digital phones are GSM. The last 4 rows look at which side of the head (L=Left, R=Right) the phone was used on. The line highlighted in red is probably the one most relevant to cancer risk assessment as it looks at long-term heavy use. |
In a study published in early 2000, Morgan and colleagues [118] studied all major causes of mortality (with emphasis on brain cancer, lymphoma and leukemia) in employees of Motorola, a manufacturer of wireless communication products. Based on job titles, workers were classified into high, moderate, low, and background RF exposure groups. For workers with moderate or high RFR exposure no elevation in rates of brain cancer, leukemia and lymphoma were found. Actual peak and/or average RFR exposure levels are not known.
The lack of associations between exposure to radiowaves and total cancer, and the lack of consistent associations between exposure to radiowaves and any specific type of cancer, suggests that radiowaves are unlikely to have a strong causal influence on cancer.
In his recent review of the RF epidemiology literature, Elwood [94]
concluded that:
Several positive associations suggesting an increased risk of some types of cancer in those who may have had greater exposure to RF emissions have been reported. However, the results are inconsistent: there is no type of cancer that has been consistently associated with RF exposures. The epidemiologic evidence falls short of the strength and consistency of evidence that is required to come to a reasonable conclusion that RF emissions are a likely cause of one or more types of human cancer. The evidence is weak in regard to its inconsistency, the design of the studies, the lack of detail on actual exposures, and the limitations of the studies in their ability to deal with other likely relevant factors. In some studies there may be biases in the data uses.
Possibly, but there is no replicated evidence for such effects. It has been suggested that amplitude-modulated (AM) RF radiation might have different effects than continuous-wave (CW, unmodulated) RF radiation. This could be important, since cell and PCS phones and base stations produce a modulated signal, and much of the research has been done with unmodulated RF sources.
This issue had been reviewed in detail by Juutilainen and de Seze [90]
who concluded that:
"The literature relevant to the possible biological effects of AM radiofrequency radiation consists of scattered observations using a wide variety of experimental models and exposure parameters... Several studies have reported findings consistent with effects on the nervous system and cancer-related biological processes. However, the methods and exposure parameters vary widely, and no independent replications of the positive finds have been reported. The results available today fail to support the existence of well-defined modulation-specific bioeffects from exposure to radiofrequency radiation."
Possibly. Some groups in the general population might be more sensitive to the effects of radiowaves than others, but no such groups have actually been found. The possible existence of such sensitive individuals is one of the main reasons that an additional 5-fold safety margin is added to the public exposure guidelines (see Q9).
See the discussion of whether children should use hand-held mobile phones in Q15H
Although the public's principle health concern about cell phone and PCS base station antennas appears to be the possibility of a cancer connection (see Q21 and Q23B-Q23D), other health-related issues come up periodically. Particularly common are questions about interference with heart pacemakers (covered in Q19A). This section will also cover less common issues. The possibility of a connection with miscarriages and birth defects is covered in Q22.
No. There is no evidence that cellular phone or PCS base station antennas will interfere with cardiac pacemakers or other implanted medical devices as long as exposure levels are kept within the ANSI standard for uncontrolled exposure (see Q8 and Q12).
It is possible that PCS phones themselves might interfere with pacemakers if the antenna is placed directly over the pacemaker. This problem is reported to occur with only some types of PCS phones and some types of pacemakers [46, 137].
There is no reason to think so. There are anecdotal reports that cell phones cause headaches (see Frey [48], and the discussion of Mild et al and Sandstrom et al [25] in Q23). There have been no serious epidemiological studies of the issue, and there are no real biophysical or physiological bases for expecting a connection.
There are unreplicated reports of such effects. There are some studies that suggest that RF radiation from hand-held mobile phones might cause subtle physiological or behavioral changes. However, none of the studies provides substantial evidence that mobile phone base stations might pose a health hazard:
- Braune et al [82] reported that human volunteers using a GSM cell phone for 35 minutes showed a 5-10 mm Hg rise in blood pressure. The study is small and was not blinded, and a rise in blood pressure of this magnitude has no known health consequences.
- Eulitz et al [84] reported that cell phones can alter the electrical activity of the brain. However, the effect may be an artifact caused by RF interference with the EEG leads.
- Freude et al [111] exposed human volunteers to RF from a 916 Mhz 350 mW GSM digital phone. Small changes in EEG were seen that "did not indicate any influence on human performance, well-being and health"
- Mann and Röschke [113] reported that exposure to a mobile phone signal could cause slight changes in sleep patterns, but a subsequent study by the same group [115] found no evidence for the effect. In a more recent study, Borbély [110] reported that exposure to a mobile phone signal at 1 W/kg could cause slight changes in sleep patterns.
- De Seze et al [113] reported that exposure of human volunteers to cell phone RF had no effect on night-time secretion of melatonin. Effects on melatonin have been suggested as a mechanism by which power line fields might affect human health (see note 4).
- Wang and Lai [109] reported that rats exposed to 2450 MHz pulsed radio-frequency radiation showed "defects in long-term memory". The RF-exposed animals were slower than normal animals to learn a maze. Animals received whole-body RF exposure for 1 hr/day. The average SAR was 1.2 W/kg with peaks of 3-4 W/kg. The signal is quite different from that associated with a mobile phone base station and the peak SAR may have been high enough to cause thermal stress. The exposure intensity (SAR) was 15 times higher than the FCC standard for whole-body exposure of the general public. In 2000 Sienkiewicz et al [120] performed a similar experiment in mice (but using a signal and a power-density simulating a European digital cell phone base station signal) and found no effects on maze performance.
In 1999, Preece et al [97] reported that exposure of human
volunteers to cell phone RF radiation might decrease reaction times (see Figure
below). The press coverage was extensive, but the actual study has no obvious
implications for human health:
Cell Phone Use and Reaction Time |
 |
| Reaction time data from Preece et al [97]. Reaction times are shown for seven separate reaction time tests. The "analog" signal was a 915 MHz sine wave. The "digital" signal was a 915 MHz sine wave modulated with a 217 Hz square wave at a 12.5% duty cycle. According to the authors, the analog test group for the "choice reaction time" test (marked in red) was considered to be significantly lower than the sham exposure value, but no other differences were considered to be statistically significant. |
In 2000, Koivisto et al [117, 132] reported studies of human volunteers who were exposed to 902 MHz RF from a 250 mW digital (GSM) phone and given a battery of reaction time tests. For some tests, exposure reduced (improved) the time required, other tests showed less significant time improvements. Some tests showed no significant effects. For the test in which Preece et al [97] found an effect for the analog signal, Koivisto et al [117] found no effect for a digital signal. The tests showing effects are stated to be tests of cognitive function. The Koivisto et al [132] conclude that:
"With respect to behavioral consequences of the RF fields in humans, all available evidence point to the same direction: RF fields facilitate rather than disrupt performance. The physiological mechanisms underlying such influences are poorly understood, and it is too early to conclude what the significance of the observed effects is on human health."
In 2000 Tsurita et al [133] reported that RF radiation had no effect on the blood-bain barrier in rats. These rats were exposed to a 1339 MHz digital (TDMA) signal for one hour per day for 2-4 weeks. The average whole body SAR was 0.25 W/kg and the brain SAR was 2 W/kg, and no changes in body temperature were observed. No effects were observed on body weight, brain morphology or blood-brain barrier permeability. The Tsurita et al [133] paper includes a detailed discussion of previous studies of RF effects on the blood-brain barrier.
For a recent review of the behavioral effects of RF radiation see D'Andrea [96].
Yes. If exposure is sufficiently intense, radiowaves can cause biological effects. Possible injuries include cataracts, skin burns, deep burns, heat exhaustion and heat stroke. Most, if not all, of the known biological effects from exposure to high-power radiofrequency sources are due to heating [20]. The effects of this heating range from behavioral changes to eye damage (cataracts) [see refs in 1, 5, 6, 7 14, 53, 83, 90, 99 and 99]. Except possibly within a few feet of the antennas themselves [128], the power produced by cellular phone and PCS base station antennas is too low to cause heating.
There have been scattered reports of effects [21] that do not appear to be due to heating, the so called non-thermal effects [20]. None of these effects have been independently replicated, and none have any obvious connections to human health risks.
The lack of biological effects from exposures to radio-frequency radiation that do not produce biologically significant temperature changes is not surprising, as there are no known biophysical mechanisms that would suggest that such effects were likely [124].
No. Even at high levels of exposure, there is no substantial evidence that radiowaves can either cause or contribute to cancer (for an opinion to the contrary see the reports discussed in Q15B and Q15C). Although research in this area has been extensive, there is no replicated laboratory or epidemiological evidence that radiowaves at the power levels associated with public exposure to radiowaves from cellular phone and PCS base station antennas are associated with cancer [see refs in 1, 5, 6, 7, 14, 74, 83, 95, 99 AND 128 for details].
There are two recent laboratory reports that RF exposure might produce cancer, or cancer-related injuries in animals. These studies are discussed in Q23B and Q23D. Both studies use RF levels far above those found in publicly-accessible area near base station antennas, and neither study has been replicated.
The epidemiological studies of RF show no consistent association with total cancer, or with any specific type of cancer (see Q16).
Indirectly, yes. Exposure to levels of radiowaves sufficient to cause whole body heating can cause miscarriages or birth defects. The power produced by cellular phone and PCS base station antennas is far too low to cause such heating. There is no laboratory or epidemiological evidence at all that radiowaves at the power levels associated with public exposure to radiowaves from cellular phone and PCS base station antennas are associated with miscarriages or birth defects [see refs in 1, 5, 6, 7 and 14 for details].
See also the discussion of Bastide et al [26] in Q23A.
There is a constant flow of new information. This section will attempt to summarize this new information. Studies which attract major attention will often get their own sections, such as the epidemiological studies discussed in Q15B, Q15C, Q15D and Q15E, the mouse studies discussed in Q23B and Q23C, and the DNA strand break studies discussed in Q23D.
A 1997 study [37] reports that lymphoma-prone mice exposed for 18 months to strong, but intermittent, radio-frequency fields of the type used by digital cellular phones have an increased incidence of lymphomas. No increases in the incidence of other types of tumors were found. The field intensities used are above the guidelines for public exposure recommended in the ANSI/IEEE standard (Q8), and are far above those that exist in publicly-accessible areas near cellular phone and PCS base station antennas [16].
While this study is very interesting, its impact on regulation of RF exposure
of the general public is quite unclear:
See the Technical notes for the reference [37], quotes from the authors' abstract [38], quotes from the authors' discussion [39], and for further technical details [40].
Several questions have been repeatedly asked about this study:
No. Before this study can be related to human risk assessment:
- it must be replicated,
- a similar study must be done with normal mice,
- the exposure-response relationship for the effect must be known,
- the induction of other types of tumors must be studied.
When you want to know whether something might cause cancer, you usually start with a sensitive strain of animals and a high dose of the agent. This maximizes your chance of finding something. If you find nothing under these circumstances, then you can be fairly confident that the agent does not cause this cancer. If you do find excess cancer, you then need to determine whether this will also happen in normal animals and/or at more reasonable doses. If you first do normal animals at low doses, and you find no excess cancer, you still would need to test cancer-prone animals at high doses.
An additional problem with using normal mice and low doses of RF to study induction of lymphoma, is that lymphoma is rare in normal mice (1-3% lifetime incidence). To detect a 50% increase in this normal rate would require over 2000 mice.
There are at least 10 other studies of long-term exposure of rodents to radiofrequency radiation. None of these studies used lymphoma-prone mice and none have reported excess lymphoma. See Q23C for details.
A difference in tumor incidence between normal animals and animals that have been genetically-altered to make them cancer prone is not unexpected, as other studies (for example, Johnson [112]) have shown that the genetically-altered animals often show different responses than normal animals in carcinogen screening tests.
It is not easy to expose animals to uniform levels of RF. If animals are unrestrained in cages, the RF dose (the SAR [8]) varies with the position of the animal, with its orientation to the antenna, with the presence of other animals, and with the animal size. To get well-defined RF doses, the animals must be confined in small holders, and the daily handling and confinement this requires can produce biological effects all by itself. Even under these conditions, the SAR may change as the animals increase in size. Basically, the experimenter has a choice: treat free-running animals with minimal disturbance and accept uncertain dosimetry, or get good dosimetry and risk artifacts due to handling and confinement. Either choice is open to criticism.
There are at least 10 other studies of long-term exposure to rodents to radio-frequency radiation.
- In 1971, Spalding el al [64] published a study of mice that had been exposed to 800-MHz RF for 2 hr/day, 5 days/week, for 35 weeks at a SAR of 13 W/kg. The average life span of the RF-exposed group (664 days) was slightly, but not significantly, longer than that of the sham group (645 days).
- In 1982 Szmigielski et al [65] published a study of mice that were exposed to 2450-MHz RF for 2 hr/day, 6 days/wk, for up to 6 months. Exposures were at 2-3 and 6-8 W/kg. Controls included both sham-irradiated animals and animals subject to "confinement stress". Both RF exposure and confinement stress significantly accelerated the appearance of both chemically-induced skin tumors and chemically-induced breast tumors. The dosimetry in this study is questionable, and seems likely that the mice exposed at the higher dose were subjected to physiologically-significant heating.
- In 1988 Saunders et al [98] published a study of male mice that were exposed to 2450-MHz RF radiation (power density of 10 mW /cm-sq and SAR of 4 W/kg) for 6 h per day for a total of 120 h over an 8-week period. At the end of the treatment the mice were mated with unexposed females. There was no significant reduction in pregnancy rate, so that there had been no increase in dominant lethal mutations. Examination of spermatogonia showed no increase in chromosome aberrations. The authors conclude that "there is no evidence in this experiment to show that chronic exposure of male mice to 2450-MHz microwave radiation induces a mutagenic response".
- In 1994 Liddle et al [66] published a study that examined the effects of life-time 2450-MHz RF exposure in mice. Mice were exposed for 1 hr/day, 5 days/week throughout their life at either 2 or 6.8 W/kg. Life span was significantly shortened in mice exposed at 6.8 W/kg (median of 572 days vs 706 days in the sham-exposed group). However, at 2 W/kg, the RF-exposed animals lived slightly, but not significantly longer (median of 738 days) than the sham-exposed group. The authors suggested that the heating from exposure at 6.8 W/kg was stressful enough to decrease life span.
- In 1992, Chou et al [43] published a study of 100 normal
rats that were exposed to pulsed 2450 MHz RF at 0.15-0.40 W/kg [8]
for 21.5 hrs/day and 25 months. No effects were observed on life-span or cause
of death. An increase in total cancer was seen in exposed group, with no effect
on survival. The malignancy rates in the controls was unusually low for this
strain, and no increase in benign tumors were observed. Two primary lymphomas
were seen in the exposed animals, and two in the controls. No benign or
malignant brain tumors were seen in either exposed or control rats.
The authors concluded:
Microwave exposure... showed no biologically significant effects on general health... The findings of an excess of primary malignancies in exposed animals is provocative. However, when this single finding is considered in light of other parameters, it is conjectural whether the statistical difference reflects a true biological influence. The overall results indicate that there are no definitive, biologically significant effects...
- In 1994, Wu et al [56] published a report on 26 mice that were exposed to a chemical carcinogen plus 2450 MHz RF at 10 mW/cm-sq (10-12 W/kg). Exposure continued for 3 hrs/day, 6 days/week for 5 months. The chemical carcinogen is one that causes colon cancer. No difference in colon cancer rates were seen between animals treated with the carcinogen alone and the animals treated with the carcinogen plus RF.
- In 1997, Toler el [45] published a report on 200 mammary-tumor-prone mice exposed to pulsed 435 MHz RF at 1.0 mW/cm-sq (0.32 W/kg). Exposure continued for 22 hrs/day, 7 days/week for 21 months. The authors reported no differences in survival or mammary tumor incidence. The authors reported that there was no difference in the rates of any types of tumors between the exposed and the control group. Of particular note, there was no difference in the lymphoma, leukemia or brain tumor rate between the exposed and the control group.
- In 1998, Frie et al [44] published a report on 100 mammary-tumor prone mice that were exposed to 2450 MHz RF at a SAR of 0.3 W/kg. Exposure was for 20 hrs/day, 7 days/week for 18 months. The study found no difference in tumor incidence or survival between the exposed and the control group. Later in 1998, Frie et al [47] published a second study using the same mouse model and the same exposure regimen, but a higher SAR of 1.0 W/kg. Again, the study found no difference in tumor incidence or survival between the exposed and the control group. There were no differences in lymphoma, leukemia or brain tumor incidence between the exposed and the control group in either study.
- In 1998 Imaida et al [63a] published a report on 48 rats that were given a chemical carcinogen that cause liver cancer, and were then exposed to 929 MHz RF an a SAR of 0.6-0.9 W/kg. Exposure was for 90 min/day, 5 days/week for 6 weeks. No difference in liver cancer rates were seen between RF-exposed rats and rats given only the chemical carcinogen.
In a second 1998 paper, Imaida et al [63b] reported a similar lack of liver cancer promotion in rats exposed to 1500 MHz RF at a SAR of 2.0 W/kg. Again, exposure was for 90 min/day, 5 days/week for 6 weeks.
- In 1998 Adey et al [24] reported that exposure to pulse-modulated 837 MHz RF did not induce or promote brain tumors in rats. RF exposure started with continuous whole-body far-field exposure of pregnant rats and continued through weaning. At 7 weeks of age, localized near-field exposure of the head was begun, and this exposure continued for 22 months (2 hrs/day, 7.5 min on - 7.5 min off, 4 days/week). Some rats were also treated with a chemical brain tumor carcinogen (ethylnitrosourea, ENU). Brain SARs ranged from 0.7 to 1.6 W/kg, and whole-body SAR ranged from 0.2 to 0.7 W/kg; the range of SARs was due to changes in weight and variability in animal positioning. The number of brain tumors was less in the RF-exposed groups than in the sham-exposed groups, but the difference was not statistically significant. This non-significant decrease was seen in both rats treated with RF alone, and in rats treated with RF plus the chemical brain tumor carcinogen.
In 2000, Adey et al [50] reported that exposure to continuous wave 837 MHz RF did not induce or promote brain tumors in rats. Other than the difference in modulation, the 2000 study used the same design and exposure protocol as the 1999 study.
- At a meeting in 1999, Zook et al [104] reported the absence of an effect on brain tumor incidence in rats exposed to 860-MHz radio-frequency radiation at 1.0 W/kg. Zook et al also reported that the same RF protocol did not promote chemically induced brain cancer.
- In 1999, Chagnaud et al [106] reported that exposure of rats to a GSM signal did not promote chemically-induced breast cancer. At various times after exposure to a chemical carcinogen, rats were exposed for 2 weeks at 2 hours per days to a 900-MHz GSM signal at 0.075 or 0.27 W/kg. No effects on tumor incidence, tumor growth or animal survival were observed.
- Also in 1999, Higashikubo et al [107] reported that exposure of rats that had brain tumors to radio-frequency radiation had no effect on the growth of these brain tumors. Rats were exposed to either 835 mHz continuous wave RFR or 848 MHz pulsed RFR at SARs of 0.75 W/kg. Exposure was for 4 hrs/day, 5 days per week, starting 28 days prior to tumor implantation and continuing for 150 days after tumor implantation.
Thus it would appear that induction of lymphoma, and tumors in general, by life-time exposure of rodents to RF is not a general phenomena.
Agents that can damage the DNA of cells are presumed to have carcinogenic potential [4]. Agents that can damage DNA are called genotoxins, or are referred to as having genotoxic activity. In general, studies of cells exposed to RF have not found evidence for genotoxicity unless the SAR was high enough to cause thermal (heat) injury [5, 6, 7, 14].
In 1995 and 1996, Lai and Singh [31] reported that RF caused DNA damage (genotoxic injury) in rats. In these experiments, rats were exposed to 2450 MHz RF at 0.6 and 1.2 W/kg. After exposure, the animals were killed, and their brain cells were analyzed for DNA injury. The authors reported an increase in DNA stand breaks 4 hours after exposure.
The work of Lai and Singh [31] has failed independent attempts at replication. In 1997, Malyapa et al [49a, 49b] reported that they could not detect the effect seen by Lai and Singh, but there were some differences between the studies. In 1998, Malyapa et al [49c] reported that they could not detect the effect in an exact replicate of the Lai and Singh [31] study.
Other recently published studies on the genotoxic potential of RF have reported no evidence for genotoxicity (damage to DNA):
On contrast, other recently published studies found some evidence for RF
exposure might be genotoxic:
Two reviews of the genotoxic potential of RF were published in 1998.
Verschaeve and Maes [80] concluded that:
"According to a great majority of papers, RF fields, and mobile telephone frequencies in particular, are not genotoxic: they do not induce genetic effects in vitro [in cell culture] and in vivo [in animals], at least under non-thermal conditions [conditions that do not cause heating], and do not seem to be teratogenic [cause birth defects] or to induce cancer."Brusick et al [81] concluded that:
"The data from over 100 studies suggest that RF radiation is not directly mutagenic and that adverse effects from exposure of organisms to high power intensities of RF radiation are predominantly the result of hyperthermia [heating]; however, there may be some subtle indirect effects on the replication and/or transcription of genes under relatively restricted exposure conditions."
The documentation of the various radiofrequency standards [5, 6, 7 and 14] contain extensive references. Reasonably up-to-date reviews of this area include: the ICNIRP publication on hand-held phones [1], the review by Stuchly [83], and the review by Repacholi [74].
This FAQ sheet was written by Dr. John Moulder, Professor of Radiation
Oncology, Radiology and Pharmacology/Toxicology at the Medical College of
Wisconsin. Dr. Moulder has taught, lectured and written on the biological
effects of non-ionizing radiation and electromagnetic fields for over two
decades.
The original version of this FAQ was written in 1995 under a contract with the
City of Brookfield, Wisconsin.
Parts of this FAQ are derived from four peer-reviewed publications:
1. International Commission on Non-Ionizing Radiation Protection: Health issues related to the use of hand-held radiotelephones and base transmitters. Health Physics 70:587-593, 1996.
2. PCS (Personal Communication Systems) phones are hand-held radiotelephones that use a digital, rather than the analog transmission system used by most cellular phones. In the U.S., cellular phones operate at 860-900 MHz, while PCS phones operate at 1800-2200 MHz. In appearance, cellular and PCS phones and their base station antennas are similar. In the U.S., "cordless" phones operate at frequencies ranging from 45 to 1800 MHz, and "citizens band (CB)" transceivers operate at about 27 MHz. Some cordless phones operate at power levels that equal or exceed some cellular phones.
International note: Around the
world a variety of other frequencies are used for both analog and digital
hand-held transceivers and mobile radios, and other names are given to the
systems (see Table 1 in Stuchly [83] for details). The most
common frequencies for "cellular" systems are 800-900 MHz (analog and
digital) and 1800-2000 MHz (digital); but hand-held transceivers exist that use
frequencies from as low as 45 MHz to as high as 2500 MHz. Power output from
hand-held units seldom exceeds 2 W, but power output from vehicle-mounted units
such as those used by law enforcement personnel can be as high as 100 W.
Canada: Analog and digital phones operate at 824-849 MHz. A 2000 MHz digital
system (similar or identical to PCS service in the US) is coming soon.
Australia: The analog AMPS phones operate at 825-890 MHz and the digital GSM
phones operate at 890-960 MHz.
Europe: Analog systems at about 900 MHz; digital (GSM) systems at about both
900 and 1800 MHz.
3. The specific frequencies used by cellular and PCS phones can be called either microwaves (MW), radiofrequencies (RF), or radiowaves. For the discussion of health effects the distinction between radiowaves and microwaves is semantic, and the term radiowaves (or radiofrequency or RF) is used in this document for all frequencies between 3 kHz and 300 GHz.
4. For a detailed discussion see:
- JE Moulder and KR Foster: Biological effects of power-frequency fields as they
relate to carcinogenesis. Proc Soc Exper Biol Med 209:309-324, 1995;
- JE Moulder: Power-frequency fields and cancer. Crit Rev Biomed Engineering
26:1-116, 1998.
5. IEEE Standards Coordinating Committee 28 on Non-Ionizing Radiation Hazards: Standard for safety levels with respect to human exposure to radio frequency electromagnetic fields, 3 kHz to 300 GHz (ANSI/IEEE C95.1-1991), The Institute of Electrical and Electronics Engineers, New York, 1992.
6. International Commission on Non-Ionizing Radiation Protection: Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields. Health Physics 74:494-522, 1998.
7. National Council on Radiation Protection and Measurements: Biological effects and exposure criteria for radiofrequency electromagnetic fields. NCRP Report No. 86, 1986.
8. The biological effects of radiowaves depend on the rate
at which power is absorbed. This rate of energy absorption is called the
Specific Absorption Rate (SAR) and is measured in watts/kilogram (W/kg). SARs
are difficult to measure on a routine basis, so what is usually measured is the
plane wave power density. Average whole body SARs can then be calculated from
the power density exposure (see Stuchly [83] for details).
Note that some documents express power density as µW/cm-sq, where 1000 µW/cm-sq
equals 1 mW/cm-sq.
9. The power density standards are stricter for cellular frequencies than for PCS frequencies because humans absorb radiowaves more at 860 MHz than at 1800 MHz, and it is the amount of power absorbed that really matters [8].
10. Specifically, the ICNIRP standard is 0.40 mW/cm-sq for cellular phone frequencies and 0.90 mW/cm-sq for PCS phone frequencies, while the NCRP guideline is 0.57 mW/cm-sq for cellular phone frequencies and 1.00 mW/cm-sq for PCS phone frequencies.
11. Guidelines for Evaluating the Environmental Effects of Radiofrequency Radiation (FCC 96-326), Federal Communications Commission, Washington, D.C., 1996. Available from the FCC web page.
12. International note --
Standards for public exposure to RF radiation from mobile phone base station
antennas in countries other than the U.S. This list is not comprehensive or
necessarily up-to-date; the information should be checked with the appropriate
regulatory authorities in each country.
Australian standard:
The Australian situation is rather complex. Until 1998, RF exposure in Australia
was regulated by "AS2772.1-1990 Radiofrequency radiation, Part 1: Maximum
exposure levels-100 kHz to 300 GHz including Amendment No. 1/1994" from the
Standards Association of Australia. In that standard the allowable general
public exposure limit for the frequencies used by mobile phone services was 0.2
mW/cm-sq; this was a factor of 2 - 6 lower than the FCC, ANSI/IEEE, ICNIRP and
NCRP standards.
This standard was revised in 1998 on an interim basis, and the allowable general
public exposure limits in the new "interim" standard
[AS/NZS2772.1(Int):1998] appeared to similar to the ICNIRP standard [6]
except at higher frequencies where the lower limits of the 1990 Standard were
retained. This interim standard was effective until 5-March-99, when it was to
have been "confirmed, withdrawn or revised". The committee responsible
for the standard was unable to achieve the required level of consensus to
confirm or revise the interim standard and it was subsequently withdrawn.
When the AS/NZS2772.1(Int):1998 lapsed, the Australian Communications Authority
(ACA) stepped in and adopted its own radiocommunications RF standard. The ACA
standard appears to be largely identical to AS/NZS2772.1(Int):1998, except that
it applies only to RF used for communications.
New Zealand standard:
In 1998 the Australian and New Zealand standards were merged as an
"interim" standard [AS/NZS2772.1(Int):1998]. The same confusion that
applied to the Australian standard occurred in New Zealand. However, unlike
Australia, New Zealand has adopted a final standard, "NZS 2772.1:1999
Radiofrequency fields - Part 1: Maximum exposure levels - 3 kHz to 300
GHz", that aligns fully with the ICNIRP Guidelines [6]
and does not contain the reduced exposure levels at higher frequencies that were
part of the earlier standards.
Canadian standard: [Health Canada: Limits of exposure to radiofrequency
fields at frequencies from 10 kHz - 300 GHz Safety Code 6, Canada Communication
Group, Ottawa, Canada, (1993)] At the frequencies of relevance to base stations
the Canadian standard appears to be identical to the FCC standard.
UK standard: The UK standard [14] is 0.57 mW/cm-sq at
900 MHz and 1.00 mW/cm-sq at 1800 MHz.
Greek standard [Measures for protection of the public from operation of
land-installed antennas. Athens, Hellenic Republic, 2000]: The standard is
essentially identical to ICNIRP [6] standard.
Swiss standard [Regulation about Protection against Nonionizing
Radiation. Swiss Federal Council, 1999]: For wireless communication transmitters
above 6 W (ERP) the standard is 4.0 V/m (0.0042 mW/cm-sq) at 900 Mz and 6.0 V/m
(0.0095 mW/cm-sq) at 1800 Mz. For broadcast radio (and TV?) the standard is
3.0-8.5 V/m (0.0024-0.019 mW/cm-sq).
Italian standard:
Ministero Dell'Ambientem, Decreto 10 settembre 1998, n. 381, Regolamento recante
norme per la determinazione dei tetti di radiofrequenza compatibili con la
salute umana.
At mobile phone frequencies the standard appears to be 0.10 mW/cm-sq. For
situations where exposure is expected to exceed 4 hours/day, the limit appears
are further reduced to 0.010 mW/cm-sq. Local regional administrations appear to
have the authority to further reduce these limits, and several regions appear to
have limits 4 times lower (0.0025 mW/cm-sq).
13. Where there are multiple transmitting antennas at different frequencies, the method for assuring adherence to the ANSI [5] or FCC [11] standards is complex. However, there is also an easy way to check adherence under these conditions: add the power densities of all the antennas and apply the strictest power density standard. Anything which passes this easy check will pass the more stringent and complex test. Something that fails this easy check must be analyzed by the more stringent and complex method described in the ANSI standard.
14. National Radiation Protection Board: Restrictions on human exposure to static and time varying electromagnetic fields and radiation. Doc NRPB 4:1-69, 1993.
15. The 1992 ANSI standard [5], for example, is based on the review of 321 papers from the peer-reviewed literature; and the NCRP guidelines [7] are based on a review of nearly 1000 reports.
16. Specifically, no potentially-hazardous effects have
been reproducibly shown below a SAR of 4 W/kg.
- At cellular and PCS phone frequencies it would require a power density of
20-100 mW/cm-sq to achieve a SAR as high as 4 W/kg.
- Under worst-case assumptions (multiple low-gain, high-ERP antennas), the SAR
of a human in publicly-accessible locations near a FCC-compliant base station
would be less than 0.01 W/kg.
- Under realistic conditions the SAR to a human near such a base station would
be less than 0.0005 W/kg.
17. ANSI, ICNIRP and NCRP all agree that whole body exposure of the general public should be kept below a whole body SAR of 0.08 W/kg. Where the standards disagree is about the specific relationship of SAR to power-density, a relationship that is determined from a combination of dosimetry and biophysical modeling.
International note: As a result of differences between approaches and frequencies used, world-wide standards for the continuous exposure of the public to RF from base station antennas ranges from 0.20 to 1.20 mW/cm-sq.
18. For the "panel" antennas used by most PCS base stations, the area of concern is only at the front of the antennas. For the "whip" style antennas used in many cellular base station antennas, the area of concern would be in all directions. This differences becomes clearer after an examination of the RF patterns from each type of antenna (see Q14C).
These general statements about minimum safe distances assume that total ERPs per sector for base station antennas will not exceed 2000 W. In the U.S., this is generally the case; and under the U.S. FCC guidelines, sites with total ERPs above 2000 W will require specific site evaluations [see note 19].
International note: More powerful antennas may be used elsewhere, in which case the minimum safe distances would be larger. Minimum safe distances will also be larger when there are multiple antennas broadcasting in the same sector.
19. Specifically, the FCC will require evaluations for:
International note: Strictly speaking, these criteria only apply in the U.S. Nevertheless, they are useful criteria for determining what types of antenna sites are most likely to violate RF standards. For example, sites that are exempted from measurement requirement under the FCC rules should also easily meet the stricter Australian standard.
20. One distinction that is often made in discussions of the biological effects of radiowaves is between "nonthermal" and "thermal" effects. This refers to the mechanism for the effect: non-thermal effects are a result of a direct interaction between the radiowaves and the organism, and thermal effects are a result of heating. There are some reported biological effects of radiowaves whose mechanisms are unknown, and it is difficult (and not very useful) to try to draw a distinction between "thermal" and "nonthermal" mechanisms for such effects.
21. These effects have included changes in the electrical activity of the brain, changes in enzyme activity, and changes in calcium ion transport across membranes [for details see 1, 5, 6, 7 and 14].
22. Santani et al: Electric fields from 900 MHz digital cellular telephones. Bioelectromagnetics Society, Tampa, June 1998.
23. The increased human absorption at 900 MHz (U.S. cell phone frequency) versus 2000 MHz (U.S. PCS phone frequency) applies to whole body exposure at a distance from the antenna (the case for public exposure near a base station antenna site). This difference may not apply to partial body exposures in very close proximity to an antenna.
24. WR Adey, CV Byus et al: Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats chronically exposed to 836 MHz modulated microwaves. Radiat Res 152:293-302, 1999.
25a. KH Mild et al: Use of mobile phones and subjective disorders. A Swedish-Norwegian epidemiological study. Background and development of questionnaire. Bioelectromagnetic Society, Tampa, June 1998.
25b: M Sandström et al: Subjective symptoms among mobile phone users in Sweden and Norway. A Swedish-Norwegian epidemiological study. Bioelectromagnetic Society, Tampa, June 1998.
26a. BJ Youbicier-Simo, JC Lebecq and M Bastide: Mortality
of chick embryos exposed to EMFs from mobile phones. Bioelectromagnetic Society,
Tampa, June 1998.
26b. BJ Youbicier-Simo, JC Lebecq and M Bastide: Damage of chicken embryos by
EMFs from mobile phones: Protection by a compensation antenna.
Bioelectromagnetic Society, Tampa, June 1998.
27. See 63b.
28. B Hocking et al: Cancer incidence and mortality and proximity to TV towers. Med J Austral 165:601-605, 1996.
29A. JR Goldsmith: Epidemiologic evidence of radiofrequency
(microwave) effects on health in military, broadcasting, and occupational
studies. Int J Occup Environ Health 1:47-57, 1995.
JR Goldsmith: Epidemiologic evidence relevant to radar (microwave) effects.
Environ Health Perspec 105:1579-1587, 1997.
30. A discussion of the problems with interpreting
ecological epidemiology studies is beyond the scope of document. For discussion
of this issue see:
S Piantadosi et al: The ecological fallacy. Am J Epidem. 127(5):893-904, 1988.
S Schwartz: The fallacy of the ecological fallacy: the potential misuse of a
concept and the consequences. Am J Public Health. 84(5):819-24, 1994.
31a. H Lai and NP Singh: Acute low-intensity microwave exposure increases DNA single-strand breaks in rat brain cells. Bioelectromag 16:207-210, 1995
31b. H Lai and NP Singh: Single- and double-strand DNA breaks in rat brain cells after acute exposure to radiofrequency electromagnetic radiation. Int J Rad Biol 69:513-521, 1996.
32. A Maes et al: 954 MHz microwaves enhance the mutagenic properties of mitomycin C. Environ Molec Mutagen 28:26-30, 1996.
33. JK Grayson: Radiation exposure, socioeconomic status, and brain tumor risk in US Air Force: A nested case-control study. Amer J Epidem 143:480-486, 1996.
34. H Dolk et al: Cancer incidence near radio and television transmitters in Great Britain I. Sutton Coldfield Transmitter. Amer J Epidem 145:1-9, 1997.
35. H Dolk et al: Cancer incidence near radio and television transmitters in Great Britain. II. All high power transmitters. Amer J Epidem 145:10-17, 1997.
36. MR Scarfi et al: Genotoxic effects of mitomycin-C and microwave radiation on bovine lymphocytes. Electro Magnetobio 15:99-107, 1996.
37. MH Repacholi et al: Lymphomas in Eµ-Pim1 Transgenic Mice Exposed to Pulsed 900 MHz Electromagnetic Fields. Rad Res 147:631-640, 1997.
38. Quotes from the abstract of Repacholi et al [37]
:
"...One hundred mice were sham-exposed and 101 were exposed for two 30-min
periods per day for up to 18 months to plane wave fields of 900 MHz with a pulse
repetition frequency of 217 Hz and a pulse width of 0.6 ms. Incident power
densities were 0.26-1.3 mW/cm-sq and [average SAR was] 0.13-1.4 W/kg. Lymphoma
risk was found to be significantly higher in the exposed mice than in the
controls (OR=2.4, p=0.006, 95% CI=1.3-4.5)... Thus long-term intermittent
exposure to RF fields can enhance the probability that mice carrying a
lymphomagenic oncogene will develop lymphomas".
39. Quotes from the discussion in Repacholi et al [37]
"[the literature] does not seem to offer a mechanism by which RF field
exposure... could increase the incidence of lymphoid malignancy"
"While the increase in the incidence of lymphoma found here was highly
significant statistically, and the exposure conditions were designed to mimic
the fields generated by a digital mobile telephone, the implications of the
study for risk of carcinogenesis in humans are unclear. It is difficult to
extrapolate directly from mice to humans due to differences in their absorption
of energy from RF fields."
"We would not interpret these studies as indicating that RF-field exposure
would be specifically lymphomagenic in normal animals."
"That is not to imply that any humans at all are necessarily at increased
risk of cancer as a consequence of exposure to RF fields. No single experiment
on animals can allow such a conclusion."
40. Further technical notes concerning Repacholi et al [37]:
- Mice used in these studies are transgenic animals that are born with an
activated oncogene that predisposes them to develop lymphoma. By the age of 10
months 5-10% of these mice develop lymphomas, and by 18 months about 15% develop
lymphomas. The incidence of lymphoma in normal mice is very much lower.
- The data analysis was blinded. The exposures themselves were not completely
blinded; during the course of the experiments the investigators knew which mice
were being exposed and which were not, but the people caring for the animals did
not.
- The RF field was not uniform in the exposure room, and the animals were
allowed to move freely in their cages during the exposure. As a result, the
actual exposure levels of the animals are not known. All that is known is that
the SAR range was 0.007 to 4.3 W/kg and that the average SAR for the mice was
0.14 to 1.4 W/kg.
- The ANSI/IEEE standard for exposure of the general public to RF is based on
keeping exposures below 0.08 W/kg. The SAR level in publicly-accessible
locations near cellular phone or PCS base stations is in the 0.0005-0.005 W/kg
range [16]. Thus the exposure levels used in this mouse study
are well above those to which people are actually exposed.
- Because the animals used in the study are genetically predisposed to lymphoma
it is difficult to decide whether this should be viewed as a test for genotoxic
activity or a test for epigenetic activity (see the
power lines-cancer FAQ for a discussion of the distinction).
41a. Vijayalaxmi et al: Frequency of micronuclei in the
peripheral blood and bone marrow of cancer-prone mice chronically exposed to
2450 MHz radiofrequency radiation. Rad Res 147:495-500, 1997.
41b. Vijayalaxmi et al: Proliferation and cytogenetic studies in human blood
lymphocytes exposed in vitro to 2450 MHz radiofrequency radiation. Int J Rad
Biol 72:751-757, 1997.
42. CD Cain et al: Focus formation of C3H/10T1/2 cells and exposure to a 836.55 MHz modulated radiofrequency field. Bioelectromag 18:237-243, 1997.
43. CK Chou et al: Long-term, low-level microwave irradiation of rats. Bioelectromag 13:469-496, 1992.
44. MR Frei et al: Chronic exposure of cancer-prone mice to low-level 2450 MHz radiofrequency radiation. Bioelectromag. 19, 20-31, 1998.
45. JC Toler et al: Long-term low-level exposure of mice prone to mammary tumors to 435 MHz radiofrequency radiation. Rad Res 148:227-234, 1997.
46. DL Hayes et al: Interference with cardiac pacemakers by cellular telephones. New Eng J Med 336:1473-1479, 1997.
47. MR Frei et al: Chronic low-level (1.0 W/Kg) exposure of mammary cancer-prone mice to 2450 MHz microwaves. Rad Res 150:568-576, 1998.
48. AH Frey: Commentary: Headaches from cellular telephones: Are they real and what are the implications? Environ Health Perspec 106:101-103, 1998.
49a. RS Malyapa et al: Measurement of DNA damage following exposure to 2450 MHz electromagnetic radiation. Rad Res 148:608-617, 1997.
49b. RS Malyapa et al: Measurement of DNA damage following exposure to electromagnetic radiation in the cellular communications frequency band (835.62 and 847.74 MHz). Rad Res 148:618-627, 1997.
49c. RS Malyapa et al: DNA damage in rat brain cells after in vivo exposure to 2450 MHz electromagnetic radiation and various methods of euthanasia. Rad Res 149:637-645, 1998.
50. WR Adey, CV Byus et al: Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats exposed to frequency-modulated microwave fields. Cancer Res. 60:1857-1863,2000.
51. T Shirai et al: Lack of promoting effects of the electromagnetic near-field used for cellular phones (929 MHz) on rat liver carcinogenesis in medium-term bioassay. 2nd World Congress, Bologna, 1997.
52. G d'Ambrosio et al: Preliminary results on human lymphocytes exposed in vitro to cellular telephone microwave frequency. 2nd World Congress, Bologna, 1997.
53. KR Foster, LS Erdreich and JE Moulder: Weak electromagnetic fields and cancer In the context of risk assessment. Proc IEEE 85:731-746, 1997.
54. Measurements show that signal strength in a building is anywhere from 5% to 40% of the level measured in the street outside. In general, signal attenuation is greater at ground level than higher up in the building, and attenuation is less at higher (PCS) frequencies than at lower (cell phone) frequencies (JD Parsons, The Mobile Phone Propagation Channel, Wiley and Sons, NY, 1992).
55. A worst-case calculation (2000 W ERP low-gain antenna mounted directly on a low-attenuation roof) predicts a power density of less than 0.10 mW/cm-sq on the floor below. A calculation for a more typical roof-top mount (1000 W ERP high-gain antenna, mounted 2 meters above a typical roof) predicts a power density of less than 0.001 mW/cm-sq on the floor below.
Actual measurements in the top floor apartments of a building with high-gain (panel) base stations antennas mounted to the outside of the parapet just above the apartments found a maximum power density of 0.0004 mW/cm-sq [101]. Measurements in a corridor in the floor directly below a roof-top base station (antennas 3 meters above the main roof) found a maximum power density of 0.008 mW/cm-sq. Both maximums assume that the base stations are operating at their maximum capacity of 2000 W ERP [101].
In 2000, NRPB (UK) [130] made measurements in multiple apartment buildings and schools that had a wide variety of mobile phone antennas on their roofs. On the top floor of these buildings the maximum RF power density from all sources combined was 0.0001 mW/cm-sq.
56. RY Wu et al: Effects of 2.45 GHz microwave radiation and phorbol ester 12-O-tetradecanoylphorbol-13-acetate on dimethylhydrazine -induced colon cancer in mice. Bioelectromag 15:531-538, 1994.
57. ED Mantiply et al: Summary of measured radiofrequency electric and magnetic fields (10 kHz to 30 GHz) in the general and work environment. Bioelectromag 18:563-577, 1997.
58. R Coghill: Something in the Air: A Biologists Review of Adverse and Beneficial Effects on Mankind, Nature and the Environment, From the Use of Radio, TV, Telecommunications, Mobile Phones, Microwaves and Electricity. Source and publisher obscure, 1997?
59. Quotes are from EMF Health and Safety Digest, Sept 1997, pp 12-13.
60. N Cherry: Potential adverse health effects of cell sites". Source and publisher obscure, 1996?.
61. Quotes are from an internet "interview" in NZine (www.nzine.co.nz) in July of 1997.
62. DR McKenzie et al: Childhood incidence of acute lymphoblastic leukemia and exposure to broadcast radiation in Sydney -- a second look. Aust New Zealand J Public Health 22:360-367, 1998.
63a. K Imaida et al: Lack of promoting effects of the electromagnetic near-field used for cellular phones (929.2 MHz) on rat liver carcinogenesis in a medium-term liver bioassay. Carcinogenesis 19:311-314, 1998.
63b. K Imaida et al: The 1.5 GHz electromagnetic near-field used for cellular phones does not promote rat liver carcinogenesis in a medium-term liver bioassay. Jap J Cancer Res 89:995-1002, 1998.
64. JF Spalding et al: Effects of 800-MHz electromagnetic radiation on body weight, activity, hematopoiesis and life span in mice. Health Phys 20:421-424, 1971.
65. S Szmigielski et al: Accelerated development of spontaneous and benzopyrene-induced skin cancer in mice exposed to 2450 MHz microwave radiation. Bioelectromag 3:179-191, 1982.
66. CG Liddle et al: Alteration of life span of mice chronically exposed to 2.45 GHz CW microwaves. Bioelectromag 15:177-181, 1994.
67. CD Robinette et al: Effects upon health of occupational exposure to microwave radiation. Amer J Epidem 112:39-53, 1980.
68. DA Hill: Longitudinal study of a cohort with past exposure to radar: the MIT Radiation Laboratory follow-up study [dissertation], University of Michigan Dissertation Service, Ann Arbor, Michigan, 1988.
69. S Milham: Increased mortality in amateur radio operators due to lymphatic and hematopoietic malignancies. Amer J Epidem 127:50-54, 1988.
70. AM Lilienfeld et al: Foreign Service Health Status Study - Evaluation of Health Status of Foreign Service and Other Employees from Selected Eastern European Posts. Final Report, Contract No. 6025-619073, United States Department of Health, Washington, D.C., 1978.
71. S Lagorio et al: Mortality of plastic-ware workers exposed to radiofrequencies. Bioelectromag 18:418-421, 1997.
72. JM Muhm: Mortality investigation of workers in an electromagnetic pulse test program. J Occup Med 34:287-292, 1992.
73. T Tynes et al: Incidence of cancer in Norwegian workers potentially exposed to electromagnetic fields. Amer J Epidem 136:81-88, 1992.
74. MH Repacholi: Radiofrequency field exposure and cancer: What do the laboratory studies suggest? Environ Health Perspec 105:1565-1568, 1997.
75. A Antonopoulos et al: Effects of high-frequency electromagnetic fields on human lymphocytes in vitro. Mut Res 395:209-214, 1997.
76. S Kwee and P Rasmark: Changes in cell proliferation due to environmental non-ionizing radiation 2. Microwave radiation. Bioelectrochem Bioenerg 44:251-255, 1998.
77. RC Petersen et al: Radio-frequency electromagnetic fields associated with cellular-radio cell-site antennas. Bioelectromag 13:527-542, 1992.
78. JL Phillips et al: DNA damage in Molt-4 T-lymphoblastoid cells exposed to cellular telephone radiofrequency fields in vitro. Bioelectrochem Bioenerg 45:103-110, 1998.
79. S Szmigielski: Cancer morbidity in subjects occupationally exposed to high-frequency (radiofrequency and microwave) electromagnetic radiation. Sci Total Environ 180:9-17, 1996.
80. L Verschaeve and A Maes: Genetic, carcinogenic and teratogenic effects of radiofrequency fields. Mut Res 410:141-165, 1998.
81. D Brusick et al: Genotoxicity of radiofrequency radiation. Environ Molec Mutagen 32:1-16, 1998.
82. S Braune et al: Resting blood pressure increase during exposure to a radiofrequency electromagnetic field. Lancet 351(9119):1857-1858, 1998.
83. MA Stuchly: Biological concerns in wireless communications. Crit Rev Biomed Eng 26:117-151, 1998.
84. C Eulitz et al: Mobile phones modulate response patterns of human brain activity. NeuroReport 9:3229-3232, 1998.
85. OM Garson, TL McRobert et al: A chromosomal study of workers with long-term exposure to radio-frequency radiation. Med J Austral 155:289-292, 1991.
86. IN Magras and TD Xenos: RF radiation-induced changes in the prenatal development of mice. Bioelectromag 18:455-461, 1997.
87. PC Goswami, LD Albee et al: Proto-oncogene mRNA levels and activities of multiple transcription factors in C3H 10T1/2 murine embryonic fibroblasts exposed to 835.62 and 847.74 MHz cellular phone communication frequency radiation. Radiat Res 151:300-309, 1999.
88. S Ray and J Behari: Physiology changes in rats after exposure to low levels of microwaves. Radiat Res 123:199-202, 1990.
89. SK Dutta, B Ghosh et al: Radiofrequency radiation-induced calcium ion efflux enhancement from human and other neuroblastoma cells in culture. Bioelectromag 10:197-202, 1989.
90. J Juutilainen and R de Seze: Biological effects of amplitude-modulated radiofrequency radiation. Scand J Work Environ Health 24:245-254, 1998.
91. JL Chagnaud and B Veyret: In vivo exposure of rats to GSM-modulated microwaves: flow cytometry analysis of lymphocyte subpopulations and of mitogen stimulation. Int J Radiat Biol 75:111-113, 1999.
92. H Lai, A Horita et al: Microwave irradiation affects radial-arm maze performance in the rat. Bioelectromag 15:95-104, 1994.
93. H Lai: Research on the neurological effects of nonionizing radiation at the University of Washington. Bioelectromag 13:513-526, 1992.
94. JM Elwood: A critical review of epidemiologic studies of radiofrequency exposure and human cancers. Environ Health Perspect 107(Suppl. 1):155-168, 1999.
95. JE Moulder, LS Erdreich et al: Cell phones and cancer:
What is the evidence for a connection? Radiat. Res., 151:513-531,1999.
On line version available.
96. JA D'Andrea: Behavioral evaluation of microwave irradiation. Bioelectromag 20:64-74, 1999.
97. AW Preece, G Iwi et al: Effect of a 915-MHz simulated mobile phone signal on cognitive function in man. Int J Radiat Biol 75:447-456, 1999.
98. RD Saunders, CI Kowalczuk et al: Studies on the induction of dominant lethals and translocations in male mice after chronic exposure to microwave radiation. Int J Radiat Biol 53:983-992, 1988.
99. Royal Society of Canada: A review of the potential risks of radiofrequency fields from wireless telecommunication devices. Royal Society of Canada, Ottawa, Ont, (http://www.rsc.ca)
100A. L Hardell, A Näsman et al: Use of cellular telephones and the risk of brain tumors: a case-control study. Int. J. Oncol. 15:113-116, 1999.
100B. L Hardell, A Näsman et al: Case-control study on radiology work, medical X-ray investigations, and use of cellular telephones as risk factors for brain tumors. Medscape General Medicine 2:2000. This is an on-line journal: http://www.medscape.com/Medscape/GeneralMedicine/journal/public/mgm.journal.html.
101. RC Petersen, AK Fahy-Elwood et al: Wireless telecommunications: Technology and RF safety issues, In: "Non-Ionizing Radiation: An Overview of the Physics and Biology", KA Hardy, ML Meltz et al (editors), Medical Physics Publishing, Madison, WI, pp. 197-226,1997.
102. LP Phillips, DB Blackwell et al: Genotoxicity of radio frequency radiation fields generated from analog, TDMA, CDMA and PCS technology evaluated using a three test in vitro battery. Environ Molec Mutagen 33 (Suppl. 30):49, 1999.
103. MV Vasquez, CJ Clancy et al: Genotoxicity of radio frequency radiation fields generated from analog, TDMA, CDMA and PCS in human blood cells evaluated using single gel (SCG) electrophoresis and the cytochalasin B micronucleus assay. Environ Molec Mutagen 33 (Suppl. 30):66, 1999.
104. CA Zook: The carcinogenicity of RF radiation to the brain of rats, Proc 11th Int Congress of Radiation Research, Radiation Research Society, Dublin, pg. 280, 1999.
105. TL Thomas, PD Stolley et al: Brain tumor mortality risk among men with electrical and electronics jobs: A case-control study. J Natl Cancer Inst 79:233-238, 1987.
106. JL Chagnaud, JM Moreau et al: No effect of short-term exposure to GSM-modulated low-power microwaves on benzo(a)pyrene-induced tumours in rat. Int J Radiat Biol 75:1251-1256, 1999.
107. R Higashikubo, VO Culbreth et al: Radiofrequency electromagnetic fields have no effect on the in vivo proliferation of the 9L brain tumor. Radiat Res 152:665-671, 1999.
108. R de Seze, J Ayoub et al: Evaluation in humans of the effects of radiocellular telephones on the circadian patterns of melatonin secretion, a chronobiological rhythm marker. J Pineal Res 27:237-242, 1999.
109. B Wang and H Lai: Acute exposure to pulsed 2450-MHz microwaves affects water-maze performance of rats. Bioelectromag 21:52-56, 2000.
110. A Borbély, R Huber et al: Pulsed high-frequency electromagnetic fields affects human sleep and sleep electroencephelogram. Neurosci Lett 275:207-210, 1999.
111. G Freude, P Ullsperger et al: Microwaves emitted by cellular telephones affect human slow brain potentials. Eur J Appl Physiol 81:18-27, 2000.
112. FM Johnson: Carcinogenic chemical-response "Fingerprint" for male F344 rats exposed to a series of 195 chemicals: Implications for predicting carcinogens with transgenic models. Environ Molec Mutagen 34:234-245, 1999.
113. K Mann and J Röschke: Effects of pulsed high-frequency electromagnetic fields on human sleep. Neuropsychobio 33:41-47, 1996.
114. LG Salford, A Brun et al: Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50 and 200 Hz. Micro Res Tech 27:535-542, 1994.
115. P Wagner, J Röschke et al: Human sleep under the influence of pulsed radiofrequency electromagnetic fields: A polysomnographic study using standardized conditions. Bioelectromag 19:199-202, 1998.
116. RA Tell: Telecommunications Antenna Installation Guidelines, Richard Tell Associates, Las Vegas, 1996. Available from CTIA, 1250 Connecticut Ave, NW, Suite 200, Washington, DC, 20036.
117. M Koivisto, A Revonsuo et al: Effects of 902 MHz electromagnetic field emitted by cellular telephones on response times in humans. Neuroreport 11:413-415,2000.
118. RW Morgan, MA Kelsh et al: Radiofrequency exposure and mortality from cancer of the brain and lymphatic/hematopoietic systems. Epidemiology 11:118-127,2000.
119. Vijayalaxmi, BZ Leal et al: Primary DNA damage in human blood lymphocytes exposed in vitro to 2450 MHz radiofrequency radiation. Radiat. Res. 153:479-486,2000.
120. ZJ Sienkiewicz, RP Blackwell et al: Low-level exposure to pulsed 900 MHz microwave radiation does not cause deficits in the performance of a spatial learning task in mice. Bioelectromagnetics 21:151-158,2000.
121. KJ Rothman, JE Loughlin et al: Overall mortality of cellular telephone customers. Epidemiology 7:303-305,1996.
122. NA Dreyer, JE Loughlin, KJ Rothman: Cause-specific mortality in cellular telephone users. JAMA 282:1814-1816,1999
123. A Thansandote, GB Gajda et al: Radiofrequency radiation in five Vancouver schools: exposure standards not exceeded. Can. Med. Assoc. J. 160:1311-1312,1999.
124. KR Foster: The mechanism paradox: Constraints on interactions between radiofrequency fields and biological systems; in M Moriarty, C Mothersill et al (eds): 11th International Congress of Radiation Research. Lawrence, KS, Allen Press, Inc., 2000, pp 222-226.
126. GI Reeves: Review of extensive workups of 34 patients overexposed to radiofrequency radiation. Aviat Space Environ Med 71:206-215,2000.
127. D dePomerai, C Daniells et al: Nonthermal heat shock response to microwaves. Nature 405:417-418,2000.
128. Independent Expert Group on Mobile Phones: Report on Mobile Phones and Health. Chilton, National Radiation Protection Board, 2000. Online at: http://www.iegmp.org.uk/IEGMPtxt.htm.
129. KR Foster, P Vecchia and M Repacholi: Science and the precautionary principle. Science 288:979-981, 2000.
130. SM Mann, TG Cooper et al: Exposure to radio waves near mobile phone base stations. National Radiation Protection Board (U.K.), June 2000.
131. KR Foster and JE Moulder: Are mobile phones safe? IEEE Spectrum, August 2000, pp 23-28. Online at: http://www.spectrum.ieee.org/publicfeature/aug00/prad.html
132. M Koivisto, CM Krause et al: The effects of electromagnetic field emitted by GSM phones on working memory. Neuroreport 8:1641-1643, 2000.
133. G Tsurita, H Nagawa et al: Biological and morphological effects on the brain after exposure of rats to a 1439 MHz TDMA field. Bioelectromag 21:364-371, 2000.
134. National Council on Radiation Protection and Measurements (U.S.): A practical guide to the determination of human exposure to radiofrequency fields. NCRP Report No. 119. Bethesda, MD, National Council on Radiation Protection and Measurements (U.S.), 1993.
135. RF Cleveland and JL Ulcek: Questions and answers about biological effects and potential hazards of radiofrequency electromagnetic fields. OET Bulletin 56, 1999. On line at: http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet56/oet56e4.pdf
136. P Gos et al: No mutagenic or recombinogenic effects of mobile phone fields
at 900 MHz detected in the yeast Saccharomyces cerevisiae. Bioelectromag
21:515-523, 2000.
137. FH Grand and RE Schlegel: Effects of increased air gap on the in vitro
interaction of wireless phones with cardiac pacemakers. Bioelectromag
21:485-490, 2000.