Cellular Phone Antennas (Mobile Phone Base Stations)
and Human Health
- This FAQ addresses the issue of whether base station transmitter/antennas for cellular phones, PCS phones, mobile phones, and other types of portable transceivers are a risk to human health.
- Issues surrounding the phones (transceivers) themselves, including the regulation of radiation-frequency radiation from the phones, are discussed only indirectly.
- Many aspects of the FAQ are also relevant to other types of broadcast antennas.
- Specific technical and regulatory sections have a US bias, but the basic engineering and biology are relevant to any country. Where possible notes have been added to help readers outside the US relate this information to their national systems.
Such notes are color coded.
- This FAQ was designed with Netscape Navigator v4.78 and for conformation with HTML 4.0 transitional.
Table of Contents
- What are mobile phone base stations; and are there health hazards associated with living, working, playing, or going to school near one?
- Are scientists seriously concerned about possible health risks
from mobile phone base station antennas?
- Do the differences between cell phones, PCS phones, and other types of portable (mobile) phones matter when evaluating the potential impacts of base station antennas on human health?
- Do the differences between mobile phone base station antennas and other types of radio and TV broadcast antennas matter when evaluating their potential impacts on human health?
- Do mobile phone base station antennas produce radiation?
- Is the non-ionizing radiation (radio-frequency radiations) from mobile phone base station antennas similar to ionizing radiations such as X-rays?
- Is the radio-frequency radiation from mobile phone base station antennas similar to the "EMF" produced by power lines?
- Are there safety guidelines for mobile phone base station antennas?
- Is there a scientific basis for these radiofrequency radiation safety guidelines?
- Are all the safety guidelines the same?
- Does the U. S. have safety guidelines for mobile phone base stations?
- Can mobile phone base station antennas meet the safety guidelines?
- Are there circumstances where mobile phone base station antennas could fail to meet the safety guidelines?
- What siting criteria are required to ensure that a mobile phone base station antenna will meet safety guidelines?
- What are some general siting criteria?
- What are the difference between a high-gain antenna and a low-gain antenna?
- What do the phrases "antenna gain", "transmitter power" and "effective radiated power (ERP)" mean?
- What is the difference between the RF patterns for high-gain and low-gain antennas?
- Is it safe to live on the top floor of a building that has a mobile phone base station antenna on it?
- Are use restrictions or "set-backs" required around mobile
phone base station antenna sites and what is the
"minimum safe distance"?
- What precautions need to be taken when working around mobile phone base station antennas?
- How do you assess compliance with radio-frequency radiation guidelines for mobile phone base stations?
- Does everyone agree with the current RF safety guidelines?
- Does the U. S. Environmental Protection Agency think that the current safety guidelines for mobile (cellular) phones are adequate?
- Has an Australian group claimed that there is evidence that living near TV broadcast towers causes an increase in childhood leukemia?
- Has an Israeli epidemiologist claimed that there is evidence that low-level RF exposure causes a variety of health effects?
- Has a British group reported excess leukemia and lymphoma around a high-power FM/TV broadcast antenna?
- Has a University of Washington (Seattle, U.S.A) researcher claimed that there is evidence that RF exposure from base stations is hazardous?
- What about the claims on British, American and French TV that
there is new data suggesting that cell phones
might cause cancer?
- What have various expert scientific panels (UK, US, Canada,
Netherlands) said about the safety of mobile phone
- Did microwave irradiation of the US Embassy in Moscow cause cancer or other injuries to people working there?
- Are there epidemiological studies showing that RF exposure from
base stations is safe?
- Could modulated RF radiation produce different effects than
the continuous-wave (CW) RF radiation used in many
- Are there groups (such as children or the elderly) that are more sensitive to the effects of radio-frequency radiations?
- Will mobile phone base station antennas affect heart pacemakers, cause headaches, etc?
- Will mobile phone base station antennas affect medical devices such as cardiac pacemakers?
- Do cell phones or cell phone base stations cause headaches?
- Does radio-frequency radiation from cell phones or cell phone
base stations cause physiological or behavioral
- Can radio-frequency radiation produce biological effects?
- Is there any replicated evidence that radio-frequency radiation can cause cancer?
- Is there any evidence that radio-frequency radiation can cause miscarriages or birth defects?
- What do the most recent scientific laboratory studies of RF radiation and cancer show?
- What about the report that exposure of mice to mobile phone RF radiation causes lymphoma?
- Has anyone else exposed rodents to mobile phone RF radiation
to see if they got cancer?
- What about the report that exposure of mice to mobile phone
RF radiation causes damage to the DNA in their
- Where can I get more information?
- Who wrote these Questions and Answers?
Additions and changes in 2001-2002:
- [Q15G] generalized to cover the comments of a number of "Blue Ribbon" groups.
- Reports from the Health Council of the Netherlands on the safety of mobile phones  and base stations .
- A new US government website on the safety and regulation of mobile phone and mobile phone base stations .
- A new French report on the safety and regulation of mobile phone and mobile phone base stations .
- [Q14F] expanded to cover the issue of "minimum safe distances"
- A new survey of maximum RF levels in schools near mobile phone base stations in the UK added to [Q12].
- A report that there were no differences were found between the biological effects continuous-wave and pulsed RF radiation .
- A report that phase-modulated RF radiation was genotoxic to human cells, but that a continuous wave signal was not .
- A report that exposure of rats to mobile phone RF radiation does not promote chemically-induced breast cancer .
- A report that mobile phone RF radiation might cause a certain type of genotoxic injury (micronucleus formation) in human blood cells, but did not cause DNA strand breaks .
- A report that mobile phone RF radiation did not cause a certain type of genotoxic injury (micronucleus formation) in mammalian cells .
- A report that exposure of mice to mobile phone RF radiation produced no detectable effect on the brain and did not mutate the DNA of their brain cells .
- A report that exposure of human volunteers to RF radiation from mobile phones improved their performance on tests for "attention" .
- A report that head-only exposure of rats to mobile phone RF radiation rat had no effect on learning .
- A report that use of mobile phones is not associated with an increased risk of acoustic neuromas (a benign brain tumor) .
- A report that exposure to RF radiation from US Navy radar during the Korean War is not associated with a subsequent increase in cancer rates .
- A detailed discussion of the "Moscow Embassy study"  as Q15H.
- New governmental reports and academic reviews:
- A report to the U.S. Congress of the state of research into the possible health effects of mobile phone RF radiation .
- A review of the history of RF radiation safety guidelines .
- A review of possible health risks from mobile phones from the World Health Organization .
- A review of possible health risks from mobile phones from the American Cancer Society .
- A review of international RF radiation safety guidelines and why they differ .
- The Royal Society of Canada report was published in a biomedical journal along with an update .
- IEEE COMAR Technical Information Statement on base stations .
- IEEE COMAR Technical Information Statement on hand-held mobile phones .
- New epidemiology studies and experimental human studies:
- Mobile phone RF radiation had no effect on melatonin levels or immune function in humans .
- Exposure to RF radiation from GSM phones had no detectable subjective effects on human volunteers .
- Headaches and other symptoms were reported to be higher in users of analog phones than users of digital phones .
- A retrospective cohort study  of all types of cancer in Danish mobile phone users. No increased risk of brain cancer, leukemia, lymphoma, ocular cancer or melanoma was found.
- In 1996, Mann and Röschke  reported that mobile phone RF caused sleep disturbance in human volunteers, when the study was repeated with a higher exposure intensity, the effect vanished .
- A report  on headaches and other symptoms reported by mobile phone users.
- A report [152, 153] that intraocular melanoma is associated with occupational use of mobile phones and other RF sources.
- A report  that RF from mobile phones affects EEG, but not memory or reaction time.
- New cellular and animal studies:
- Exposure of mice to digital mobile phone RF radiation did not promote chemically-induced skin cancer . See Q23B.
- Exposure of mice to RF radiation did not promote chemically-induced skin cancer . See Q23B.
- Exposure of normal mouse cells and human tumor cells to digital or analog mobile phone RF radiation had no effect on their growth .
- RF radiation was not mutagenic in bacteria (the Ames test) . See Q23C.
- RF radiation did not cause chromosome damage in rats . See Q23C.
- Exposure of mice to digital or analog mobile phone RF radiation did not promote cancer (particularly lymphoma) induced by ionizing radiation . See Q23A and Q23B.
- Mobile phone RF radiation did not cause chromosome damage in human blood cells .
- RF radiation at 4 W/kg had no effect on the blood-brain barrier of mice .
- A study of RF radiation effects on "stress" responses in animals  found that restraint of animals for the exposure produced effects, but the RF radiation exposure itself did not.
- Zook and Simmens  reported the absence of an effect on brain tumor incidence in rats exposed to continuous-wave or pulsed RF radiation at 1.0 W/kg.
- No increase in cancer in mice exposed to ultra-wide band RF pulses .
- No evidence for genotoxic or epigenetic activity in human lymphocytes exposed to 600 MHz GSM at 0.4-10 W/kg for 4 hrs .
- RF exposure of pregnant rats had no affect in their offspring .
- RF radiation may induce heat shock in worms without a detectable rise in temperature .
- RF radiation did not damage chromosomes and did not enhance the activity of known carcinogens .
- RF radiation did not cause cell transformation .
- RF radiation did not cause chromosome damage and did not enhance micronucleus formation .
- New dosimetry and biophysical studies:
- A report on the near impossibility of assessing RF radiation exposure from mobile phone base stations without site specific measurements or calculations .
- An analysis  of exposure levels to a person on a roof near a base station antenna.
- A theoretical examination finds that nonthermal effects of RF radiation are implausible .
Questions and Answers
1) What are mobile phone base stations; and are there health hazards associated with living, working, playing, or going to school near one?
Mobile phone base stations are low-power multi-channel two-way radios. A mobile phone (cell phone) is a low-power, single-channel, two-way radio. When you talk on such a mobile phone, you (and perhaps dozens of other people around you) are talking to a nearby base station. From that base station your phone call goes into the regular land-line phone system.
Because mobile phones and their base stations are two-way radios, they produce radio-frequency radiation (that's how they communicate), and they expose people near them to radio-frequency (RF) radiation. However, because both the phones and the base stations are low power (short range), the RF radiation exposure levels from them are generally very low.
The consensus of the scientific community, both in the US and internationally, is that the power from these mobile phone 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 RF radiation; and towers or masts, the structures that the antennas are placed on. It is the antennas that people need to keep their distance from, not the towers that hold the antennas.
It is also important to be aware that there are many different designs of mobile phone base stations that vary widely in their power, their characteristics, and their potential for exposing people to RF radiation.
2) Are scientists seriously concerned about possible health risks from mobile phone base station antennas?
Not really. There are some reasons to be concerned about human health effects from the hand-held mobile (cellular) phones themselves (although it is not certain that any risks to human health actually exist). These concerns exist because the antennas of these phones deliver much of their radiofrequency energy to very small volumes of the user's body . Base station antennas do not create such "hot spots" (unless you are standing directly in front of one), 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 1996 ICNIRP report 
- the 1999 and 2000 reviews by Moulder and colleagues [95, 131]
- the 2000-2001 review by the Royal Society of Canada 
- the 2000 report of the UK Independent Expert Group on Mobile Phones (the "Stewart Commission") 
- the 2001 IEEE position paper 
- the 2001 review from the World Health Organization 
- the 2001 the review from American Cancer Society 
- the 2001 report from the US GAO 
- the new (in 2002) US FCC/FDA website 
- the 2002 report from the Health Council of the Netherlands 
3) Do the differences between cell phones, PCS phones, and other types of portable (mobile) phones matter when evaluating the potential impacts of base station antennas on human health?
No. There are many technical differences between cell phones, PCS phones, and the types of "mobile" 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 RF radiation from some base stations (e.g., those for the older 800 MHz cell phones used in the U.S.) may be absorbed by humans somewhat more than the RF radiation from other types of base stations (e.g., those for the 1800-2000 MHz "PCS" phones used in the U.S.) . However, once the energy is absorbed the effects are the same.
4) Do the differences between base station antennas and other types of radio and TV broadcast antennas matter when evaluating their potential impacts on human health?
Yes and no. The RF radiation from some antennas (particularly FM and VHF-TV broadcast antennas) are absorbed more by humans than the RF radiation from other sources (such as mobile phone base station antennas); but once the energy is absorbed the effects are basically the same.
FM and TV antennas send out 100 to 5000 times more power than base station antennas, but are usually mounted on much higher towers (typically 800 to 1200 ft).
5) Do mobile phone base station antennas produce radiation?
Yes. Mobile (cellular) phones and their base station antennas are two-way radios, and produce radiofrequency (RF) radiation ; 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].
6) Is the non-ionizing radiation (RF radiation) from mobile phone base station antennas similar to ionizing radiations such as X-rays?
No. The interaction of biological material with an electromagnetic source depends on the frequency of the source . X-rays, RF radiation 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 (wave) per second, and 1 megahertz (MHz) is one million cycles (waves) 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 million MHz. Cellular (mobile) phones operate at a variety of frequencies between about 800 and 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 RF radiation, the energy of the particles is much too low to break chemical bonds. Thus RF radiation is "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 (RF radiation) .
The Electromagnetic Spectrum
7) Is the RF radiation from mobile phone base station antennas similar to the "EMF" produced by power lines?
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 RF radiation produces biological effects [4, 53]. There appears to be no similarity between the biological effects of power line "EMF" and the biological effects of RF radiation.
8) Are there safety guidelines for mobile phone base station antennas?
Yes. There are national and international safety guidelines for exposure of the public to the RF radiation produced by mobile phone 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, 169], the International Commission on Non-Ionizing Radiation Protection (ICNIRP) , and the National Council on Radiation Protection and Measurements (NCRP) .
These radiofrequency standards are expressed in "plane wave power density", which is measured in mW/cm-sq (milliwatts per square centimeter) [8, 169]. For PCS (about 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 . The ICNIRP standards are slightly lower and the NCRP standards are essentially identical .
In 1996 the U.S. Federal Communications Commission (FCC) released radiofrequency guidelines for the frequencies and devices they regulate, including mobile phone base station antennas . The FCC standards for mobile phone base station antennas are essentially identical to the ANSI/IEEE standard .
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 mobile phone frequencies). Where there are multiple antennas, these standards apply to the total power produced by all antennas .
See international note 12 and Erdreich and Klauenberg .
9) Is there a scientific basis for these radiofrequency radiation safety guidelines?
Yes. When scientists examined all the published literature on the biological effects of RF radiation they found that the literature agreed on a number of key points [see 1, 5, 6, 7, 14, 53, 83, 90, 95, 96, 99, 164, and 169 for details]:
- The research on RF radiation is extensive , and is adequate for establishing safety guidelines.
- Exposure to RF radiation can be hazardous if the exposure is sufficiently intense. Possible injuries include cataracts, skin burns, deep burns, heat exhaustion and heat stroke. See Reeves  for a discussion of the known effects of overexpose to RF radiation in humans.
- Biological effects of RF radiation depend on the rate of energy absorption ; and within a broad range of frequencies (1 to 10,000 MHz), the frequency matters very little.
- Biological effects of RF radiation are proportional to the rate of energy absorption; and the duration of exposure matters very little .
- No biological effects have been consistently shown below a certain rate of whole body energy absorption (this rate is called the specific absorption rate or SAR) .
Based on this scientific consensus, different agencies and countries took different approaches to setting safety guidelines. A typical approach was that used by ANSI/IEEE  and the FCC .
To establish occupational exposure guidelines, ANSI/IEEE and FCC applied a 10-fold safety margin to the lowest energy absorption rate shown to have biological effects. 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 the energy absorption rate (SAR), which really matters .
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.
10) Are all the safety guidelines the same?
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, 164, 169]. 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  and ICNIRP , they do differ. See note 12 and Erdreich and Klauenberg  for details.
11) Does the U. S. have safety guidelines for mobile phone base stations?
Yes. Until 1996 the U. S. Federal Communications Commission (FCC) used an out-dated (1982) ANSI standard. In 1996 the FCC adopted a new standard  that was based on a combination of the 1992 ANSI standard [5, 169] and the 1986 NCRP guidelines .
The new FCC standard for mobile phone base stations is 0.57 mW/cm-sq at 900 MHz and 1.0 mW/cm-sq at 1800-2000 MHz. 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 , the FCC guideline itself , and Foster and Moulder .
12) Can mobile phone base station antennas meet the safety guidelines?
Yes. With proper design, mobile phone base station antennas can meet all safety guidelines by a wide margin.
A mobile phone base station antenna, mounted 10 meters (33 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 guidelines, and the standards themselves are set far below the level where potentially hazardous effects have been seen.
Within about 200 meters (650 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 on the same tower, power densities will be less than 5% of the FCC guidelines at all heights and at all distances of more than 55 meters (180 ft) from an antenna site.
Further than about 200 meters (650 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].
Petersen et al  measured power densities around cell phone base stations. The measurements were for 1600 W (ERP) antennas (see Q14C for a discussion of antenna power) on towers that ranged from 40 to 83 meters (130 to 275 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 (65-265 feet) from the base of the towers. Within 100 meters (330) 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  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.
RF Levels in Canadian Schools Near Cell Phone Base Stations
||Base Station Location
||Maximum RF Level
||PCS base station across street
||analog base station on roof
||analog base station across street
|4 and 5
||no antennas nearby
||less than 0.00001 mW/cm-sq
||less than 0.57 mW/cm-sq
In 2000, the U.K. National Radiation Protection Board  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. .
In 2001, the Radiocommunications Agency of the UK Department of Trade and
Industry measured RF radiation levels at 100 schools
that had mobile phone base stations near them. The maximum
RF level measured at any school what less than 1% of
the ICNIRP standard  for public
areas; the maximum in most schools was less than 0.1%
of that standard.
Radiofrequency Radiation Levels in Schools Near Mobile Phone Base Stations in the UK
(in comparison to the ICNIRP guidelines for public areas)
Maximum RF radiation levels (in comparison to the ICNIRP standard for public areas) in UK schools that have mobile phone base stations near them.|
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).
13) Are there circumstances where mobile phone base station antennas could fail to meet the safety guidelines?
Yes. There are some circumstances under which an improperly designed (or inadequately secured) mobile phone base station antennas could fail to meet safety guidelines.
Safety guidelines for uncontrolled (public) exposure could be exceeded if antennas were mounted in such a way that the public could gain access to areas within 6 meters/20 feet (horizontal) of the antennas themselves . This could arise for antennas mounted on or near the roofs of buildings. Petersen et al , for example, found that 2-3 feet (1 meter) from a 1600 W (ERP) roof-top antenna, the power density was as high as 2 mW/cm-sq (compared to the ANSI  public exposure standard of 1.2 to 0.57 mW/cm-sq). For antennas mounted on towers, it is very difficult to imagine a situation that would not meet the safety guidelines.
14) What siting criteria are required to ensure that a mobile phone base station antenna will meet safety guidelines?
While specific recommendations require a detailed knowledge of the site, the antenna, and the mounting structure, some general criteria can be described.
14A) What are some general siting criteria?
- Antenna sites should be designed so that the public cannot access areas that exceed the 1992 ANSI  or FCC  guidelines for public exposure. As a general rule, the uncontrolled (public) exposure guideline cannot be exceeded more than 6 meters (20 feet) from an antenna .
- If there are areas accessible to workers that exceed the 1992 ANSI  or FCC  guidelines for uncontrolled (public) exposure, make sure workers know where the areas are, and what precautions need to be taken when entering these areas. In general, this would be areas less than 6 meters (20 feet) from the antennas .
- If there are areas that exceed the 1992 ANSI  or FCC  guidelines for controlled (occupational) exposure, make sure that workers know where these areas are, and that they can (and do) power-down (or shut down) the transmitters when entering these areas. Such areas may not exist; but if they do, they will be confined to areas within 3 meters (10 feet) of the antennas .
If there are questions about whether these guidelines are met, compliance should be verified by measurements done after the antennas are activated.
The FCC guidelines  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 .
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:
See international note 19.
- Antennas placed on the roofs of buildings; particularly where multiple base station antennas for different carriers are mounted on the same building;
- Antennas placed on structures that require access by workers (both for regular maintenance, and for uncommon events such as painting or roofing).
14B) What are the difference between a high-gain antenna and a low-gain antenna?
There are many different types of base station antennas, and the RF radiation patterns from them can be quite different. The most basic difference is between high-gain antennas and a low-gain antennas. Because siting and safety issues for high- and low-gain antennas are different, it is important to be able to tell them apart (see Q14B for a discussion of antenna gain). In the early days of mobile phones, you could usually tell by looking. Unfortunately, the development of newer antenna designs and the variety of different ways to stealth (hide) antennas now often makes it impossible to determine what kind of antenna has been installed just by looking,
14C) What do the phrases "antenna gain", "transmitter power" and "effective radiated power (ERP)" mean?
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 were omni-directional and 100% efficient, then transmitter power and ERP would be the same. But mobile phone base station antennas (like all 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, and it is measured in decibels. As a result, a 20-50 W base station transmitter with a high-gain antenna could produce an ERP of anywhere from several hundred watts to over 1000 watts.
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 sector 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 .
14D) What is the difference between the RF patterns for high-gain and low-gain antennas?
The RF patterns for different types of antennas are very different. For a low-gain antenna with a 1000 W ERP (see Q14C for a discussion of antenna power and gain) of the type formerly used by many cell phone base stations, the pattern can look like this:
RF Radiation from a 1000 W ERP Low-Gain Antenna on a 15 m Tower
For a high-gain (sector) antenna of the type used in many of the newer base stations, the pattern can look like this:
RF Radiation from a Single 1000 W ERP High-Gain Antenna Mounted 2 m above the Roof of a 13 m Building
Keep in mind that mobile phone base station that use high-high-gain sectored antennas will usually use 3 (or occasionally 4) of these transmission antennas, all pointing in different directions.
The data for the above figure were adapted (with permission) from drawings provided by UniSite Inc. of Tampa, Florida.
14E) Is it safe to live on the top floor of a building that has a mobile phone base station antenna on it?
In general this will not be a problem.
- As can be seen from the antenna patterns shown in Q14D, neither high- or low-gain antennas radiate much energy straight down.
- The roof of the building will absorb large amounts of the RF energy. Typically a roof would be expected to decrease signal strength by a factor of 5 to 10 (or more for a reinforced concrete or metal roof).
- FCC will require RF evaluations of all but the most low-powered roof-top transmitters (see note 19).
- Even a worst-case calculation predicts that power density on the floor below an antenna will meet all current RF safety guidelines .
- Actual measurements in top floor apartments and corridors confirm the power density will be far below all current RF safety guidelines .
14F) Are use restrictions or "set-backs" required around mobile phone base station antenna sites and what is the "minimum safe distance"?
Radiofrequency safety guidelines do not require either setbacks or use restrictions around mobile phone 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.
The "Minimum Safe Distance" from a mobile phone
base antenna is described by the FDA/FCC 
"To be exposed to levels at or near the FCC limits for cellular or PCS frequencies an individual would essentially have to remain in the main transmitted radio signal (at the height of the antenna) and within a few feet from the antenna... In addition, for sector-type antennas RF levels to the side and in back are insignificant."
Note that the above quote about safe distances applies to the actual radiating antenna, not to the tower the antenna is on. For a mobile phone base station antenna mounted on tower that is 5+ meters high, there should be no areas that will come anywhere close to the RF radiation safety guidelines, so the concept of a "minium safe distance" really doesn't mean anything.
Some people have argued that base stations should be kept some distance away from "sensitive" areas.
There is little logic to this argument:
- As discussed in Q12 and documented in the 2000 NRPB report , the ground level power density does not drop with distance in any regular manner until you get about at least several hundred meters away from a base station.
- People living, working or studying in a building usually get less exposure from a base station that is on their building than they would from a base station several hundred meters away (Q12 and Note 130).
- Horizontal distance from a base station is less of a factor in ground level power density than antenna height, the antenna power and antenna pattern.
In addition, moving base antennas away from an area where there are mobile phone users may:
- Increase the exposure of the users from their handsets.
- Require the base antenna power to be increased.
- Require the base antennas to placed further above the ground.
- Increase the cell size and limit the number of users.
14G) What precautions need to be taken when working around mobile phone base station antennas?
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  makes the following recommendations:
Specific Antenna Installation Guidelines (from Tell )
- For roof-mounted antennas, elevate the transmitting antennas above the height of people who may have to be on the roof.
- For roof-mounted antennas, keep the transmitting antennas away from the areas where people are most likely to be (e.g., roof access points, telephone service points, HVAC equipment).
- For roof-mounted directional antennas, place the antennas near the periphery and point them away from the building.
- Consider the trade off between large aperture antennas (lower maximum RF) and small aperture antennas (lower visual impact).
- Remember that RF standards are stricter for lower-frequency antennas (e.g., 900 Mhz) than for higher-frequency antennas (e.g., 1800 MHz).
- Take special precautions to keep higher-power antennas away from accessible areas.
- Keep antennas at a site as far apart as possible; although this may run contrary to local zoning requirements.
- Take special precautions when designing "co-location" sites, where multiple antennas owned by different companies are on the same structure. This applies particularly to sites that include high-power broadcast (FM/TV) antennas. Local zoning often favors co-location, but co-location can provide "challenging" RF safety problems.
Work Practices for Reducing Radio-frequency Radiation Exposure (from Tell )
- Individuals working at antenna sites should be informed about the presence of RF radiation, the potential for exposure and the steps they can take to reduce their exposure.
- "If radiofrequency radiation at a site can exceed the FCC standard for general public/uncontrolled exposures, then the site should be posted with appropriate signs." [Per Richard Tell, personal communication, Feb 2000]
- Radio-frequency radiation levels at a site should modeled before the site is built.
- Radio-frequency radiation levels at a site should measured.
- Assume that all antennas are active at all times.
- Disable (lock out) all attached transmitters before working on an antenna.
- Use personal monitors to ensure that all transmitters have actually been shut down.
- Keep a safe distance from antennas. "As a practical guide for keeping [radio-frequency radiation] exposures low, maintain a 3-4 ft [1-1.2 m] distance from any [telecommunications] antenna." 
- "Keep on moving" and "avoid unnecessary and prolonged exposure in close proximity to antennas".
- At some site (e.g., multiple antennas in a restricted space where some antennas cannot be shut down) it may be necessary to use protective clothing.
- Remember that there are many non-RF hazards at most sites (e.g., dangerous machinery, electric shock hazard, falling hazard), so allow only authorized, trained personnel at a site.
Also see Bernardi et al  for an analysis of actual exposure levels to a person on a roof near a base station antenna.
14H) How do you assess compliance with radio-frequency radiation guidelines for mobile phone base stations?
Compliance can be assessed through measurements or calculations. Both methods require a solid understanding of the physics of RF radiation. Measurements require access to sophisticated and expensive equipment. Calculations require detailed knowledge about the power, antenna pattern and geometry of a specific antenna.
Nothing as simple as distance from an antenna site is adequate for assessing compliance or estimating exposure levels [113, 171]. As discussed and illustrated in Q12, RF radiation exposure may not even increase as you get closer to an mobile phone base station site.
Calculation: If the effective radiated power (ERP), the antenna pattern and the height of the base station antenna is known (see Q14C for a discussion of ERP and gain), then "worst case" calculations of ground level power density can be made. However, the calculation method is not simple and the ERP and antenna pattern are often unknown.
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, or ICNIRP guidelines 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 ).
Calculations (and sometimes even measurements) must take into account possible sources of RF radiation other than the mobile antenna site being assessed [113, 171]. It is not unusual for there to be other RF radiation signals that are stronger than those from the base station being assessed.
For a technical discussion of measurement techniques and instrumentation see Mann et al  and NCRP Report No. 119 .
15) Does everyone agree with the current RF safety guidelines?
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.
15A) Does the U. S. Environmental Protection Agency (EPA) think that the current safety guidelines for mobile (cellular) phones are adequate?
Yes. The EPA asked the FCC to adopt parts of the 1986 NCRP guidelines  rather than the entire 1992 ANSI guidelines . This the FCC did , and EPA has formally endorsed the FCC safety guidelines.
In a 25-Jul-96 letter to Reed Hundt (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 Hundt (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."
15B) Has an Australian group claimed that there is evidence that living near TV broadcast towers causes an increase in childhood leukemia?
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  published an "ecological" epidemiology study that compares municipalities "near TV towers" to those further away. No RF radiation 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  repeated the Hocking study . McKenzie and colleagues looked at the same area, and at the same time period; but they made more precise estimates of the exposure to RF radiation 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 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  was an artifact.
15C) Has an Israeli epidemiologist claimed that there is evidence that low-level RF exposure causes a variety of health effects?
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 Q15H and Hill );
- the "geographical correlation" studies of Hocking et al  and Dolk et al [34, 35] that are discussed in Q15B and Q15D;
- the study of Korean war radar operators by Robinette et al  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, 94, 139); and even fewer would be willing to base a conclusion on the types of data sources that Goldsmith relies on.
15D) Has a British group reported excess leukemia and lymphoma around a high-power FM/TV broadcast antenna?
Yes and no. Dolk and colleagues  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  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  or by Hocking et al  in Australia.
15E) Has a University of Washington (Seattle, U.S.A) researcher claimed that there is evidence that RF exposure from base stations is hazardous?
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 , and substantially exceeds the SAR limit that forms the basis of the FCC  and ANSI  safety guidelines for public exposure . For further discussion of the research on possible effects of RF radiation on the nervous system see reviews by Lai  and Juutilainen and de Seze .
At a meeting in Vienna in 1998, and in a letters sent to public officials, 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:
- Changes in the blood-brain barrier (Salford et al, 1997). An as-yet unpublished meeting presentation; for earlier work from this group see Salford et al, 1994 .
- Changes in cell proliferation (Kwee and Rasmark, 1997). This is an unpublished study that may be the same as that published by Kwee and Rasmark in 1998 .
- Decreased fertility in mice (Magras and Xenos, 1997) .
- Decreased eating and drinking in mice (Ray and Behari, 1990) .
- Changes in calcium transport in cells (Dutta et al, 1989) .
- DNA damage (Phillips et al, 1998) .
A review of the above studies finds little actual support for Dr. Lai's claim.
- One of the studies, the report of effects on the blood-brain barrier by Salford et al, has never been published and cannot be evaluated. Note that in 2000-2001, Tsurita et al  and Finnie et al  reported that RF radiation had no effect on the blood-brain barrier of rats or mice.
- Two of the studies [78, 88] do not actually report any statistically-significant effects.
- Ray and Behari  reported that exposed animals "tended" to eat and drink less than the controls, and that the effect disappeared by the end of the exposure period.
- Phillips et al  reported that exposure caused increased DNA damage in 3 of 12 exposure regimens and decreased DNA damage in 4 of the other 9 regimens. The study found no overall effect and no pattern.
- The statistical significance of the "effects" reported in two other studies [76, 89] is open to question, as the effects reported are very small and appear in only some experiments.
- Dutta et al  reported increased calcium efflux for only 6 of the 19 exposure regimens that were tested. Since the increases were unrelated to exposure intensity or frequency, they may be a multiple comparison artifact.
- The "effect" reported by Kwee and Rasmark  is a 5-10% decreases in cell growth that was statistically significant in only 5 of 9 trials.
- Two of the studies [86, 88] have inadequate control groups, so that if there is an effect, there is no way to be certain that it was due to the RF.
- Magras and Xenos  compared mouse fertility in breeding pairs kept in an "antenna park" with those kept in a laboratory. The conclusion that the effect on breeding was due to the RF rather than other environmental factors is purely speculative.
- Ray and Behari  tightly confined their animals during exposure, but did not appear to similarly confine their controls. This type of "confinement stress" is known to cause changes in physiology and behavior (see discussion of Szmigielski et al  in Q23B) and see Stagg et al .
- Several of the studies [88, 89] also use RF radiation intensities that substantially exceed anything that would be found in public areas near an FCC-compliant base station.
- Many of the "effects" reported have no known relationship to any human health hazard. For example, neither the changes in calcium efflux reported by Dutta et al , the small decreases in cell growth reported by Kwee and Rasmark , nor the small changes in food consumption reported by Ray and Behari  have any known significance for human health.
- All of the "effects" quoted by Dr. Lai have been the subject of other studies that have shown no such effects, including studies done at substantially higher field intensities.
15F) What about the claims on British, American and French TV that there is new data suggesting that cell phones might cause cancer?
There appears to have been no real scientific basis for these claims.
In the summer and fall of 1999 (and repeated in 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 study by Hardell et al  that is discussed in Q16.
- The study by Preece et al  that is discussed in Q19C.
- A new and then unpublished genotoxicity study.
- A new and then unpublished epidemiology study.
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 WTR epidemiology study was presented at a meeting
in June of 1999, and has now been published in the peer-reviewed
The published version reports no significant association
between malignant  or benign
 brain cancer and the use of
hand-held cell phones. See further discussion of the
study in Q16.
The WTR genotoxicity study was presented at a meeting in March of 1999 [102, 103]. Parts of this WTR study were finally published in early 2002 . The published version  reports that RF radiation at 5 or 10 W/kg was capable of causing a one specific type of genotoxic injury (increased micronucleus formation); but did not enhance DNA strand breaks. Vijayalaxmi et al  and Bisht et al  have already reported that they cannot confirm the micronucleus findings. The authors of the WTR genotoxicity study speculate that their reported effect on micronucleus formation my be due to heating.
15G) What have various expert
scientific panels (UK, US, Canada, Netherlands) said about
the safety of mobile phone base stations?
In 2000, a special committee in the U.K., the "Independent Expert Group on Mobile Phones" (also known as the "Stewart Commission") issued a report on mobile phone safety issues . The full text is available at: 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  and ICNIRP  guidelines do not cause adverse health effects to the general population... There is now scientific evidence, however, which suggests that there may be biological effects occurring at exposures below these guidelines. This does not necessarily mean that these effects lead to disease or injury, but it is potentially important information..." [Sections 1.17 and 1.18]
The "new scientific information" the Stewart Commission refers to is largely the reaction time studies of Preece et al  and Koivisto et al  that are discussed in Q19C, and studies by dePomerai et al [127, 148] 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]
- "...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  and Koivisto et al  and on the European Union "Precautionary Principle" . This rationale for this recommendation has been criticized on multiple grounds:
- The notion that there may be neurological effects at the SAR levels produced by hand-held mobile phones is based on reports of effects that are both weak and contradictory.
- There is no evidence that the reported cognitive effects would cause an adverse health effect, and the reported effects appear to be too small to have any real functional significance.
- The Committee provided no evidence to justify the premise that children are more susceptible to the reported effects, other than to speculate about the susceptibility of the "developing nervous system". Since most nervous system development is done by the end of infancy, the relevance of this to phone use by teenagers is unclear.
- The suggestion that phones will produce higher SARs in the head of a child compared to an adult was provided without any supporting argument.
- The Committee's application of the precautionary principle to children's exposure to hand-held mobile phones appears to violate the guidelines established by the European Union .
An Expert Panel assembled by the Royal Society of Canada issued a report on mobile phone safety in 1999 .
Regarding mobile phone base stations, the Expert Panel concluded:
"Surveys conducted in proximity to base stations operating in Canada indicate that the public is exposed to extremely low intensity RF fields in the environment. These exposures are typically thousands of times lower than the recommended maximum exposure in Safety Code 6."
In 2001 the Institute of Electrical and Electronics Engineers (IEEE) published a statement on mobile phone base stations .
The statement concluded that:
"In nearly all circumstances, public exposure to RF fields near wireless base stations is far below recommended safety limits... Consequently, wireless base stations are not considered to present a risk to the general population including aged people, pregnant women, and children"
"The electromagnetic RF signals transmitted from base station antennas stations travel toward the horizon in relatively narrow paths... Therefore, RF exposure on the ground is much less than exposure very close to the antenna and in the path of the transmitted radio signal. In fact, ground-level exposure from such antennas is typically thousands of times less than the exposure levels recommended as safe by expert organizations. So exposure to nearby residents would be well within safety margins."
"Measurements made near cellular and PCS base station antennas mounted on towers have confirmed that ground-level exposures are typically thousands of times less than the exposure limits adopted by the FCC. In fact, in order to be exposed to levels at or near the FCC limits for cellular or PCS frequencies an individual would essentially have to remain in the main transmitted radio signal (at the height of the antenna) and within a few feet from the antenna..."
"When cellular and PCS antennas are mounted on rooftops, RF levels on that roof or on others near by would probably be greater than those typically encountered on the ground. However, exposure levels approaching or exceeding safety guidelines should be encountered only very close to or directly in front of the antennas..."
In 2002, the Health Council of the Netherlands issued a report on the safety of mobile phones . On the general issue of mobile phone safety, the Health Council concluded that:
"The electromagnetic field of a mobile telephone does not constitute a health hazard, according to the present state of scientific knowledge."
With respect to mobile phone base stations, the Health Council reaffirmed their earlier (2000) conclusion  that:
"The chance of health problems occurring among persons living and working below bases stations as a result of exposure to electromagnetic fields originating from the antennas is, in the Committee's opinion, negligible. The field levels are always considerably below the exposure limits."
In 2001, the Directeur Général de la Santé issued a report on the safety of mobile phones and their base stations (Les Téléphones Mobiles, leurs Stations de Base et la Santé) . On the general issue of mobile phone safety, the French report concluded that:
"The risk of accident and fatality associated with the use of mobile telephones when driving has definitely been established. In the current state of knowledge, this is the only known health risk, albeit a very serious one."
With respect to mobile phone base stations, the report concluded that:
"There is considerably less personal exposure in the vicinity of base stations with the exception of exclusion areas than there is when making a call with a mobile phone...In view of the exposure levels observed, the group of experts does not back the hypothesis that there is a health risk for populations living in the vicinity of base stations."
15H) Did microwave irradiation of the US Embassy in Moscow cause cancer or other injuries to people working there?
The exposure to RF radiation occurred, but there is no real evidence that it caused any health effects.
From 1953 to 1976, low-intensity microwaves were aimed at the American Embassy building in Moscow. Lilienfeld et al  performed a comprehensive survey of the health experience of 1827 foreign service employees who had been assigned to work at the embassy (and their dependents). Their health experience was compared to 2561 foreign service workers assigned to other East European embassies (and their dependents). Measurements of several different exposed areas of the Moscow embassy in three time periods indicated the maximum exposure was at 0.015 mW/cm-sq (at 0.5 to 9 GHz) for 18 hours/day. For most of the exposure period, the maximum level was lower. The embassies of the comparison population were said to be at background levels.
Lilienfeld et al  found no evidence that individuals in the Moscow group experienced higher mortality for any cause, or higher mortality from cancer in general or from any cancer subtype. Although this study was well-designed, the relatively small cohort size and short follow-up time limited its power. The power of this study is also limited by the extremely low RF radiation levels, although it should be noted that the RF levels are larger than those found near most mobile phone base station antennas.
The study concluded that:
"Personnel working in the American Embassy in Moscow suffered no ill effects from the microwaves beamed at the Chancery"
16) Are there epidemiological studies showing that RF exposure from base stations is safe?
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 radiofrequency radiation. For reviews see Elwood  and Rothman .
In general, epidemiology studies of radiofrequency radiation and cancer have not found significant correlations between exposure and cancer. The studies include:
- geographic correlation studies that compare cancer rates among areas with different potential exposures to radiofrequency radiation
- "cancer cluster" studies
- studies of cancer in people with military or occupational exposure to radiofrequency radiation
- users of hand-held mobile phones
Geographic correlation studies
Geographic correlation studies estimate the strength of RF radiation 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.
The geographical correlation studies done to date show no consistent relationship between exposure to RF radiation and either adult of childhood cancer. See Q15B, Q15D and Elwood  for further discussion of these studies.
Cancer cluster studies
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 RF radiation, and reports of "cancer clusters" are of essentially no value in determining whether exposure to RF radiation is a cause of cancer (see Elwood  for details of these studies).
Occupational exposure studies
The majority of the occupational studies of RF radiation exposure have deficiencies in exposure assessments because occupation or job title was used as an estimate of exposure; that is, actual RF radiation exposure levels are not known.
There are five epidemiological studies of occupational exposure to RF radiation that are generally considered to have acceptable design and analysis, adequate sample size, and sufficient follow-up time: Robinette et al , Hill , Milham , Morgan et al  and Groves et al . These five studies do not show consistent associations between exposure to radio-frequency radiation and either cancer in general or any specific kind of cancer.
In a study published in early 2000, Morgan and colleagues  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 RF radiation exposure no elevation in rates of brain cancer, leukemia and lymphoma were found. Actual peak and/or average RF radiation exposure levels are not known.
In a study published in 2002, Groves et al 
reported that exposure to RF radiation from US Navy
radar during the Korean War is not associated with a
subsequent increase in cancer rates. In comparison with
navy men who served at the same time, but who had "low
radar exposure potential", the sailors with "high radar
exposure potential" showed less overall cancer and brain
cancer than expected. The rate of nonlymphocytic leukemia
was elevated, but the authors note that this increase
was statistically significant in only one of the three
high exposure occupations. This is a follow-up study
to Robinette et al .
The other studies of acceptable design (Lilienfeld et al , Lagorio et al , Muhm , Tynes et al , Grayson , and Thomas et al ) have more limitations in exposure assessment, case ascertainment, or follow-up time; but they also do not suggest that RF radiation exposure increases the risk of either cancer in general or any specific kind of cancer.
Szmigielski  studied Polish military personnel who may have had RF radiation 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 RF radiation exposure is very deficient, the report does not meet basic epidemiological criteria for acceptability. Elwood  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".
Studies of exposure to mobile phone RF radiation
In 1996, Rothman et al.  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 car-mounted mobile phones (where the antenna is mounted on the vehicle). In a 1999 follow-up study , 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 car-mounted mobile phones. The only specific cause of death that correlated with use of hand-held mobile phones was death from motor vehicle collisions.
In 1999-2001, four studies evaluated brain cancer in users of hand-held mobile phones: the first by Hardell et al , the second by Muscat et al , the third by Inskip et al , and the fourth by Johansen et al . None of studies found associations between mobile phone use and brain cancer (see figure below), and none found exposure-response trends. In general, the temporal lobe of the brain gets the highest RF radiation exposure in users of hand-held cell phones; Hardell et al  reported a non-significant excess of temporal lobe tumors, but Muscat et al , Inskip et al  and Johansen et al  reported a non-significant decrease of these tumors. Hardell et al  reported a non-significant excess of temporal lobe tumors on the side of the head where the patients reported using their phones, but Muscat et al  and Inskip et al  reported non-significant trends in the opposite direction (see details below).
In the first of the mobile phone case-control studies, Hardell et al.  analyzed mobile phone use in 233 Swedish brain tumor patients, some of whom has used hand-held mobile phones for as long as 10 years. This was done 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 mobile 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 lobe (or temporal, occipital plus temporoparietal lobe) tumors on the same side of the brain where the cell phone was reported to have been used, a non-significant excess incidence of brain cancer was found. This "handedness" was seen for use of analog phones, but not for the use of digital phones.
Brain Cancer in Users of Hand-Held Mobile Phones
Relative risk of brain cancer (with 95% confidence interval) in users of hand-held cell phones from the epidemiological studies of Hardell et al , Muscat et al , Inskip et al , and Johansen et al . The number of exposed cases in the overall analysis, and the sub-analyses are shown in parentheses. The top set of relative risks looks at the least restrictive definition of "mobile phone use" reported by each group, the middle set of relative risks looks at the group with the longest use analyzed by each group, and the bottom group looks at tumors in the lobe of the brain expected to get the highest exposure to RF radiation.
In December 2000, Muscat et al  published a similarly-designed study of 469 brain tumor patients in the US, some of whom has used hand-held mobile phones for as long as 4 years. Exposure was assessed on the basis of in-hospital interviews. No elevation of brain tumor incidence was found in users of hand-held phones, and no exposure-response trend was observed (see figure above). The incidence of temporal lobe tumors (where RF radiation exposure should be the greatest in users of hand-held phones) was not elevated. There was a non-significant trend for tumors to be on the side of the head where the patients reported using their phones; but when analysis was confined to the temporal lobe tumors, there were fewer tumors than expected on the side of the head where the phones were used.
When Muscat et al  analyzed tumors by histopathological type, there was no excess of gliomas (the most common and deadly form of brain tumors); but there was an excess of neuroepitheliomas. This increase was not statistically significant. Hardell et al.  did not explicitly analyze this histopathological subtype of tumor, but Inskip et al  found a decreased incidence of neuroepitheliomas.
As soon as Muscat et al  was published, NEJM rushed a similar study onto their website that had been scheduled for publication in January of 2001. Inskip et al  studied 782 brain tumor patients in a different part of the US, some of whom had used hand-held mobile phones for as long as 5 years. They found no elevation of brain tumor incidence in users of hand-held phones, and observed no exposure-response trend (see figure above). The incidence of temporal lobe tumors (where RF radiation exposure should be the greatest in users of hand-held phones) was not elevated. There was a non-significant trend for tumors to be on the side of the head opposite to where the patients had reported using their phones. When Inskip et al  analyzed tumors by histopathological type, there was no significant excess of any types of malignant or benign brain tumors.
In early 2001, Johansen et al  published a retrospective cohort study of all types of cancer in Danish mobile phone users, some of whom has used cell phones as long as 5 years. This included 154 brain cancer patients. Mobile phone use was associated with a significantly decreased overall risk of cancer that was attributable largely to less smoking-related cancer. No increased risk of brain cancer, leukemia, lymphoma, ocular cancer or melanoma was found in mobile phone users. No significant increase in any types of cancer were found in mobile phone users. No exposure response trends in leukemia or brain cancer incidence were seen in cell phone users. There was no increase in temporal or occipital lobe tumors in cell phone users (see figure above).
In the accompanying editorial [155B] Park wrote:
"Regardless of how convincing the evidence exonerating cell phones may be, there will continue to be those who will argue that the issue has not been completely settled. In science, few things ever are. The scientific community has a responsibility to put all the evidence into perspective for the public."
In January 2001, Stang et al  reported that the use of "radio sets, mobile phones, or similar devices at [the] workplace for at least several hours per day" was associated with uveal (intraocular) melanoma. Of 118 individuals with intraocular melanoma, 6 (5.1%) reported that they were "probable or certain" to have "ever been exposed" to mobile phones at work. According to the authors, this occupational mobile phone use is 4 times higher than expected. Mobile phone use outside of work was not assessed, and other risk factors (for example, UV exposure and light skin color) were not assessed. In the only other comparable study, Johansen et al  found less melanoma and ocular cancer than expected in cell phone users. According to the accompanying editorial :
Stang and colleagues raise the possibility that we should add a new type of cancer to those already under leading consideration as possible hazards of RF radiation, and it may well be that future studies will support their hypothesis. At this point , however, given the small size of the study, the relatively crude exposure assessment, the absence of attention to UVR exposure or other possible confounding variables, and limited support from the literature, a cautious interpretation of their results is indicated.
In 2002 Muscat et al  reported that use of mobile
phones was not associated with an increased risk of
acoustic neuromas (a benign brain tumor). This study
parallels Muscat's earlier report 
on malignant brain tumors and the use of hand-held mobile
phones. The tumors that were found in mobile phone users
were more likely to be on the side opposite where the
phone was used, than one the side where the phone was
reported to have been used.
Summary of the epidemiology
The lack of associations between exposure to RF radiation and total cancer, and the lack of consistent associations between exposure to RF radiation and any specific type of cancer, suggests that RF radiation is unlikely to have a strong causal influence on cancer.
In a 1999 review of the RF epidemiology literature, Elwood  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 used
In a 2000 review of the RF epidemiology literature, Rothman  concluded that:
Based on the epidemiological evidence available now, the main public health concern is clearly motor vehicle collisions, a behavioral effect rather than an effect of RF exposure as such. Neither the several studies of occupational exposure to RF nor the few of cellular telephone users offer any clear evidence of an association with brain tumors of other malignancies. Even if the studies in progress were to find large relative effects for brain cancer, the absolute increase in risk would probably be smaller than the risk stemming from motor vehicle collisions.
17) Could modulated RF radiation produce different effects than the continuous-wave (CW) RF radiation used in many laboratory studies?
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 (see for example Hyland . This could be important, since mobile phones and their 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  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.
For recent reports of attempts to find differences between the biological effects of continuous-wave and modulated RF radiation, see Pakhomov et al  (who reported no difference) and 'D'Ambrosino et al  (who reported a difference).
18) Are there groups (such as children or the elderly) that are more sensitive to the effects of RF radiation?
Possibly. Some groups in the general population might be more sensitive to the effects of RF radiation 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 Q15G
19) Will mobile phone base station antennas affect heart pacemakers, cause headaches, etc?
Although the public's principal health concern about mobile phone base station antennas appears to be the possibility of a cancer connection (see Q21 and Q23A-Q23C), 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.
19A) Will mobile phone base station antennas affect medical devices such as cardiac pacemakers?
No. There is no evidence that mobile phone base station antennas will interfere with cardiac pacemakers or other implanted medical devices as long as exposure levels are kept within the ANSI guideline for uncontrolled exposure (see Q8 and Q12).
It is possible that digital mobile 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 digital phones and some types of pacemakers [46, 137].
19B) Do cell phones or cell phone base stations cause headaches?
It is possible that use of cell phones causes headaches.
In 1998, Frey  reported anecdotal evidence that cell phones cause headaches.
In 2000, Oftedal et al  found that users of cell phones commonly report having headaches, but since the study contains no data on non-users it is not known whether the rate of headaches reported by these cell phone users is unusual. An extension of the study by Sandström et al  reported that headaches and other symptoms were higher in users of analog (NMT 900) phones than users of digital (GSM) phones.
In 2000, Chia et al  reported that headaches were significantly more common among users of hand-held cell phones than among non-users (65% vs 54%). Headache prevalence increase significantly with duration of use, and the use of hand-free equipment eliminated the increase.
No one has claimed that there is scientific evidence that base stations cause headaches, and there are no biophysical or physiological bases for expecting such an effect.
19C) Does radio-frequency radiation from cell phones or cell phone base stations cause physiological or behavioral changes?
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:
- None of the "effects" reported imply the existence of hazards.
- All of these studies used radio-frequency radiation of an intensity far above those associated with mobile phone base stations.
- Most of these reports have not been independently confirmed, and there are grounds for being skeptical about most of them.
- Braune et al  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  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  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"
- In 1996 Mann and Röschke  reported that exposure to a mobile phone signal at 0.05 mW/cm-sq could cause slight changes in sleep patterns; but subsequent studies by the same group found no significant effect when the power density was lowered to 0.02 mW/cm-sq , and no effect at all when the power density was increased to 5 mW/cm-sq .
- In 1999, Borbély, Huber and colleagues [110, 141] reported that exposure to a mobile phone signal at 1 W/kg could cause slight changes in sleep patterns and sleeping EEG.
In 1999, De Seze et al  reported that exposure of human volunteers to cell phone RF had no effect on night-time secretion of melatonin. In 2001, Radon et al  reported a similar lack of effect of mobile phone RF radiation on melatonin levels in humans. Effects on melatonin have been suggested as a mechanism by which power line fields might affect human health (see note 4).
- Wang and Lai  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  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  reported that exposure of human volunteers to cell phone RF radiation might decrease reaction times. The press coverage was extensive; but the actual study has no obvious implications for human health, since the effect was seen for just one of many tests of cognitive function and it appears to be far too small to have any real functional significance.
- 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  found an effect for the analog signal, Koivisto et al  found no effect for a digital signal. The tests showing effects are stated to be tests of cognitive function. In further studies in 2001, Koivisto et al  found that a 30-60 minute exposure to RF radiation from GSM phones had no detectable subjective effects on human volunteers.
- In 2000, Krause et al  reported a study of human volunteers who were exposed to 902 MHz RF from a 250 mW digital (GSM) phone and given memory and reaction time tests. Effects on error rate and reaction time were not significant. Some effects on EEG were observed under some test conditions. According to the authors: "The present results do not allow any conclusions concerning the possible effects of cellular phone use on cognition".
- In 2000 Tsurita et al  reported that RF radiation had no effect on the blood-brain 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  paper includes a detailed discussion of previous studies of RF effects on the blood-brain barrier. In a similar study in 2001, Finnie et al  reported that RF radiation at 4 W/kg had no effect on the blood-brain barrier of mice.
- In 2000, Bornhausen and Scheingraber  reported that exposure of pregnant rats to RF radiation has no effect on the behavior of their off-spring. Free-roaming pregnant rats were continuously exposed to 900 MHz GSM RF at 0.1 mW/cm-sq (SARs ranged from 17.7-75 mW/kg). No cognitive deficits were found in their offspring.
In 2002, Edelstyn and Oldershaw 
reported that exposure of human volunteers to 900 MHz
RF radiation from mobile phones improved their performance
on tests for "attention".
Also in 2002, Dubreuil et al 
reported that head-only exposure of rats to 900 MHz
pulsed RF radiation (SAR of 1 or 3.5 W/kg) for 45 minutes
had no effect on learning.
For a 1999 review of the behavioral effects of RF radiation see D'Andrea .
20) Can RF radiation produce biological effects?
Yes. If exposure is sufficiently intense, RF radiation 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 . The effects of this heating range from behavioral changes to eye damage (cataracts) [see refs in 1, 5, 6, 7 14, 53, 83, 90 and 99]. Except possibly within a few feet of the antennas themselves , the power produced by mobile phone base station antennas is too low to cause heating.
There have been scattered reports of effects  that do not appear to be due to heating, the so called non-thermal effects [20, 25, 158]. 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 [25, 124, 158, 165 ].
In a 2001 review, Pickard and Moros  conclude that:
"The prospects of UHF (300-3000 MHz) irradiation producing a nonthermal bioeffect are considered theoretically and found to be small... This supports previous arguments for the improbability of biological effects at UHF frequencies unless a mechanism can be found for accumulating energy over time and space and focusing it. Three possible mechanisms are then considered and shown to be unlikely... Finally, it is concluded that the rate of energy deposition from a typical fields and within a typical tissue is so small as to make unlikely any significant nonthermal biological effect."
21) Is there any replicated evidence that RF radiation can cause cancer?
No. Even at high levels of exposure, there is no substantial evidence that RF radiation 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 RF radiation at the power levels associated with public exposure to RF radiation from mobile phone 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 laboratory reports that exposure to RF radiation might produce cancer, or cancer-related injuries in animals. These studies are discussed in Q23A and Q23C. 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).
22) Is there any evidence that RF radiation can cause miscarriages or birth defects?
Indirectly, yes. Exposure to levels of RF radiation sufficient to cause whole body heating can cause miscarriages or birth defects. The power produced by mobile phone base station antennas is far too low to cause such heating. There is no laboratory or epidemiological evidence at all that RF radiation at the power levels associated with public exposure to RF radiation from mobile phone base station antennas are associated with miscarriages or birth defects [see refs in 1, 5, 6, 7 and 14 for details].
23) What do the most recent scientific laboratory studies of RF radiation and cancer show?
There is a constant flow of new information. Studies which attract major attention will often get their own sections, such as the mouse and rat cancer studies discussed in Q23A and Q23B, and the DNA strand break studies discussed in Q23C.
23A) What about the report that exposure of mice to mobile phone RF radiation causes lymphoma?
A 1997 Australian study by Repacholi et al  reported that lymphoma-prone mice exposed for 18 months to strong, but intermittent, RF radiation 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 guideline (Q8), and are far above those that exist in publicly-accessible areas near mobile phone base station antennas .
While this study is interesting, its impact on regulation of RF exposure of the general public is quite unclear, as it cannot be determined from the study whether lymphomas can be induced in normal (as opposed to cancer-prone) animals by exposure to RF radiation, or what level of RF radiation exposure level is required for induction of lymphoma in cancer-prone mice.
Clearly the study will need to be repeated with both normal and lymphoma-prone mice. If the effect can be replicated, it will be critical to determine the dose-response relationship for lymphoma induction, and to determine whether the effect occurs for other tumors and/or in other species.
Several questions have been repeatedly asked about this study:
- Does this study mean that mobile phones cause cancer?
- Before this study can be related to human risk assessment it must be replicated, a similar study must be done with normal mice, and the exposure-response relationship for the effect must be known.
- In the first direct attempt at confirmation of the Repacholi et al study, Heikkinen et al  reported that exposure of mice to mobile phone RF radiation did not increase the incidence lymphoma induced by exposure of the mice to ionizing radiation. The major difference between the studies is that Heikkinen et al  made their animals lymphoma-prone by exposing them to ionizing radiation; while Repacholi et al  made their mice lymphoma-prone via a genetic alteration.
- If it is so difficult to extrapolate from these cancer-prone mice to humans, why were they used?
- 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.
- Do we know whether exposure to cell phone radiation causes lymphoma in normal animals?
- There are at least 15 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 Q23B for details.
- A difference in tumor induction between normal animals and animals that have been genetically-altered to make them cancer prone is not unexpected, as other studies (for example, Johnson ) have shown that the genetically-altered animals often show different responses than normal animals in carcinogen screening tests.
- Why is the level of RF radiation exposure in this study so poorly-defined?
- It is not easy to expose animals to uniform levels of RF radiation. If animals are unrestrained in cages, the RF dose (the SAR ) varies with the position of the animal, with the animals's orientation to the antenna, with the presence of other animals, and with the animal's size. To get well-defined RF radiation exposure, the animals must be confined in small holders, and the daily handling and confinement this requires can produce biological effects all by itself (see Stagg et al ). 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.
23B) Has anyone else exposed rodents to mobile phone RF radiation to see if they got cancer?
There are at least 20 other studies of long-term exposure to rodents to radio-frequency radiation.
- In 1971, Spalding el al  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-exposed group (645 days).
- In 1982 Szmigielski et al  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" (see Stagg et al ). 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  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  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  published a study of 100 normal rats that were exposed to pulsed 2450 MHz RF at 0.15-0.40 W/kg  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  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  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  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  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  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  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.
- In 1999, Chagnaud et al  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  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 RF radiation or 848 MHz pulsed RF radiation 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.
- In 2001, Zook and Simmens  reported the absence of an effect on brain tumor incidence in rats exposed to continuous-wave or pulsed 860-MHz radio-frequency radiation at 1.0 W/kg. Exposure was for 6 hrs/day, 5 days/week for 22 months, starting when the rats were 2 months old. Zook and Simmens also reported that the same RF protocols did not promote chemically induced brain cancer. No statistically-significant RF-related increases in overall cancer or any specific types of cancer (including lymphoma) were found.
- Later in 2001, Jauchem et al  reported that there were no significant effects on mammary tumor development or animal survival in mammary tumor-prone mice exposed to pulses composed of an ultra-wideband (UWB) of frequencies, including those in the RF range. Histopathological evaluations revealed no significant effect on the numbers of neoplasms in any tissue studied (including lymphomas).
- Also in 2001, Heikkinen et al  reported that exposure of mice to RF radiation of the type used by analog or digital mobile phones did not increase the incidence of cancer (particularly lymphoma) induced by ionizing radiation. Mice were exposed to ionizing radiatio and then to pulsed (GSM-type) or continuous wave (NMT-type) RF radiation. RF radiation exposure was at 1.5 W/kg (analog signal) or 0.35 W/kg (digital signal) for 1.5 hrs/days for 78 weeks. No increase in any types of cancer were observed in the animals exposed to RF radiation.
- 2001 also saw two reports that RF radiation did not promote chemically-induced skin cancer. Imaida et al  reported that pulsed RF radiation of the type used by Japanese digital mobile phones did not increase the incidence of chemically-induced skin cancer in mice. Imaida et al  tested both promotion and co-promotion (with TPA) protocols, and found no promotion in either. Mason et al  also reported the absence of promotion or co-promotion of chemically-induced skin cancer in mice exposed to 94 GHz RF radiation.
In 2002, Bartsch et al  reported
that exposure of rats to mobile phone RF radiation does
not promote chemically-induced breast cancer. The rats
were exposed to a chemical breast cancer carcinogen
and for life-time to pulsed 900 MHz RF radiation at
0.1 mW/cm-sq (SAR of 0.018-0.070 W/kg). No effect on
latency or incidence of benign or malignant breast cancer
were found. Interesting, prior to publication it had
been widely claimed (although not by the authors) that
this study would show significant effects on breast
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.
23C) What about the report that exposure of mice to mobile phone RF radiation causes damage to the DNA in their brain cells?
Agents that can damage the DNA of cells are presumed to have carcinogenic potential . 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  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 
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  study.
In 2002, Tice et al  also reported
that RF radiation did not cause DNA strand breaks. In
a related 2002 study, Takahashi et al 
reported that head-only exposure of mice to 1500 MHz
RF radiation at 0.7 and 2.0 W/kg (90 min/day, 5 days/week,
for 4 weeks) did not produce mutations in their brain
Other recently published studies on the genotoxic potential of RF have reported no evidence for genotoxicity (damage to DNA):
- Vijayalaxmi et al [41a, 41b, 119] found no evidence for genotoxic injury in the blood cells of mice exposed to 2450 MHz RF for 18 months at 1 W/kg; or in human lymphocytes exposed in cell culture to 2450 MHz RF at 2.1 or 12.5 W/kg.
- Cain et al  found no effect of 836 MHz RF exposure at 0.015 W/kg on neoplastic cell transformation in animal fibroblasts.
- Antonopoulos et al  found no effects of RF exposure on cell growth or chromosome injury in human lymphocytes. Cells were exposed to RF for 48-72 hrs at 380 MHz (SAR=0.08 W/kg), 900 MHz (SAR=0.2 W/kg) or 1800 MHz (GSM, SAR=1.7 W/kg).
- Gos et al  reported that RF radiation of the type produced by GSM phones (at 0.13 or 1.3 W/kg) was not mutagenic and did not enhance the activity of a chemical carcinogen.
- Maes et al  reported that RF radiation exposure of human blood cells at 6.5 W/kg did not damage chromosomes, did not enhance the activity of a chemical carcinogen, and did not enhance chromosome damage induced by X-rays.
- Roti Roti et al  reported that RF radiation (analog or digital) exposure of mammalian cells at 0.6 W/kg did not cause cell transformation.
- Vijayalaxmi et al [150, 167] reported that RF radiation exposure of human blood cells at 4.4-5.5 W/kg did not cause chromosome damage.
- Maes and Collier  found no increase in chromosome aberrations or SCE in human lymphocytes exposed to 600 MHz GSM at 0.4-10 W/kg for 4 hrs. RF exposure also did not enhance the genotoxic effects of X-rays or of a chemical carcinogen (tests for epigenetic activity).
- Teichman et al  reported that RF radiation of type used in MRI did not cause mutations in a bacterial test system (the Ames assay).
- Vijayalaxmi et al  reported that exposure of mice to RF radiation for 24 hours at 12 W/kg did not cause chromosome injury in their blood or bone marrow cells.
- Bisht et al  reported that mobile phone RF radiation
did not cause increased micronucleus formation in
In contrast, other recent studies found some evidence for RF exposure might be genotoxic:
- Maes et al  reported that exposure of human blood cells to 954 MHz RF at 1.5 W/kg did not cause chromosome damage, but increased the amount of chromosome damage produced by a chemical carcinogen.
- Scarfi et al  reported that exposure of animal white blood cells to 9000 MHz RF at 70 W/kg produced caused genotoxic injury and enhanced the genotoxic injury caused by a chemical carcinogen. However, the SAR in this experiment was high enough to cause thermal (heat) injury, so the relevance to real-world human exposure is unclear.
- Phillips et al  exposed mammalian cells to RF for 2 or 21 hours at 814 or 827 MHz. The SAR was 0.0002 or 0.002 W/kg. Both increases and decreases in the incidence of DNA strand breaks were observed, with no obvious pattern.
- D'Ambrosio et al  reported that phase-modulated 1748
MHz RF radiation was genotoxic to human cells at 5
W/kg (micronucleus assay), but that a continuous wave
signal was not.
- Tice et al  reported that while RF radiation did
not cause DNA strand breaks, it might enhance micronucleus
Two reviews of the genotoxic potential of RF were published in 1998.
Verschaeve and Maes  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  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."
24) Where can I get more information?
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 .
- The review by Stuchly .
- The review by Repacholi .
- The 2001 review from the World Health Organization .
- The 2001 review from the American Cancer Society .
- The new (in 2002) US FCC/FDA website 
- The 2000 report from the Health Council of the Netherlands .
25) Who wrote these Questions and Answers?
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 since the late 1970's.
The original version of this FAQ was written in 1995 under a contract with the City of Brookfield, Wisconsin. The FAQ has been maintained and expanded since 1995 as a teaching aid at the Medical College of Wisconsin. The web server and web management is provided by the General Clinical Research Center at the Medical College of Wisconsin. The development and maintenance of this document is not supported by any person, agency, group or corporation outside the Medical College of Wisconsin.
Parts of this FAQ are derived from the following peer-reviewed publications:
- KR Foster, LS Erdreich, JE Moulder: Weak electromagnetic fields and cancer in the context of risk assessment. Proc IEEE, 85:733-746, 1997.
- JE Moulder: Power-frequency fields and cancer. Crit Rev Biomed Eng 26:1-116, 1998.
- JE Moulder, LS Erdreich, RS Malyapa, J Merritt, WF Pickard, Vijayalaxmi: Cell phones and cancer: What is the evidence for a connection? Radiat. Res., 151:513-531, 1999.
- KR Foster and JE Moulder: Are mobile phones safe? IEEE Spectrum, August 2000, pp 23-28.
- KR Foster and JE Moulder: Mobiles et cancer, un vrai casse-tête. La Recherche 337:39-47, 2000.
- KR Foster, P Vecchia et al: Effetti sulla salute dei telefoni mobili. AEI 87:36-41, 2000.
- JE Moulder: Radiaciones de Radiofrecuencias y Cancer: Efectos Biologicos y Posibles Mecanismos. In: P. Gil-Loyzaga and A. Ubeda Eds. , Ondas Electromagneticas y Salud, Informes Sanitarios, Siglo XXI, No. 1, Madrid, Spain, pp: 287-336, 2002.
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 two-way radios that use a digital, rather than the analog transmission system used by most "cell phones". In the U.S., most of the older 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 2500? MHz, and "citizens band (CB)" two-way radios 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  for details). The most common frequencies for "cellular" systems are 800-900 MHz (analog and digital) and 1800-2200 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 around 800-900 MHz, and there is a new 2000 MHz digital system (similar or identical to PCS service in the US).
Australia: The analog AMPS phones operate around 800-900 MH\z and the digital GSM phones operate around 900-1000 MHz.
Europe: Analog systems at about 900 MHz; digital (GSM) systems at around both 900 and 1800 MHz.
3. The specific frequencies used by mobile (cellular) phones can be called either microwaves (MW) or radiofrequencies (RF) or radiofrequency radiation (RFR) or radiowaves. For the discussion of health effects the distinction between radiowaves and microwaves is semantic, and the term radiowaves (or radiofrequency or RF or RFR) 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 RF radiation 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  for details).
Note that some documents express power density as µW/cm-sq (microwatts/cm-sq), where 1000 µW/cm-sq (1000 microwatts/cm-sq) equals 1 mW/cm-sq.
9. The power density guidelines are stricter for some frequencies than for others because humans absorb RF radiation more at 860 MHz than at 1800 MHz, and it is the amount of power absorbed that really matters .
10. Specifically, the ICNIRP standard is 0.40 mW/cm-sq at 800 MHz and 0.90 mW/cm-sq at 2000 MHz, while the NCRP guidelines are 0.57 mW/cm-sq and 1.00 mW/cm-sq for these same 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. Also see Erdreich and Klauenberg .
- 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  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 radiation 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  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: In mid-2000 the UK stopped using its own standard for mobile phones and mobile phone base stations  and adopted the ICNIRP standard .
- 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  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 MHz and 6.0 V/m (0.0095 mW/cm-sq) at 1800 MHz. 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  or FCC  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 , for example, is based on the review of 321 papers from the peer-reviewed literature; and the NCRP guidelines  are based on a review of nearly 1000 reports.
16. Specifically, no potentially-hazardous effects have been consistently shown below a SAR of 4 W/kg.
- At mobile 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 high-gain sector antennas used by most newer base stations, the area of concern is only at the front of the antennas. For the low-gain antennas used in many older base stations, 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 Q14D). Unfortunately, the RF radiation pattern from an antenna cannot always be determined from looking at it.
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:
"rooftop" is defined as: "the roof or otherwise outside, topmost level or levels of a building structure that is occupied as a work place or residence and where either workers or the general public may have access." I would assume that a mount on a water tower would be considered "non-rooftop"
- non-rooftop 1800-2000 MHz base station antennas less than 10 meters (30 feet) off the ground and with a total ERP of greater than 2000 W (3280W EIRP);
- rooftop 1800-2000 MHz base station antennas with a total ERP of greater than 2000 W (3280W EIRP).
- non-rooftop 800-900 MHz base station antennas less than 10 meters (30 feet) off the ground and with a total ERP of greater than 1000 W (1640W EIRP);
- rooftop 800-900 MHz base station antennas with a total ERP of greater than 1000 W (1640W EIRP)
- see Q14C for a discussion of ERP
"total power" is defined as: "the sum of the ERP or EIRP of all co-located simultaneously operating transmitters of the facility. When applying the [exclusion] criteria, radiation in all directions should be considered. For the case of transmitting facilities using sectorized transmitting antennas, applicants and licensees should apply the criteria to all transmitting channels in a given sector, noting that for a highly directional antenna there is relatively little contribution to ERP or EIRP summation for other directions."
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.
20. One distinction that is often made in discussions of the biological effects of RF radiation 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 RF radiation and the organism, and thermal effects are a result of heating. There are some reported biological effects of RF radiation 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. Also see Valberg , Foster  and Pickard and Moros .
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]. Also see Hyland .
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.
25. PA Valberg: Radio frequency radiation (RFR): the nature of exposure and carcinogenic potential. Cancer Causes Control 8:323-332, 1997.
26. Human Exposure to Radio Frequency and Microwave Radiation from Portable and Mobile Telephones and Other Wireless Communication Devices, A COMAR Technical Information Statement. IEEE Eng Med Biol, Jan/Feb 2001, pp 128-131.
27.Safety Issues Associated With Base Stations Used for Personal Wireless Communications, A COMAR Technical Information Statement. IEEE Eng Med Biol, Mar/Apr 2001, pp 110-114.
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.
29B. 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.
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 (1800-2000 MHz) frequencies than at lower (800-900 MHz) 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 sector 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 . 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 .
In 2000, NRPB (UK)  made measurements in multiple apartment buildings and schools that had a wide variety of mobile phone base station 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.
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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.
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This FAQ is Copyright©, 1996-2002 by John Moulder and the Medical College of Wisconsin, and is made available as a service to the Internet community.
Portions of this FAQ are derived from the following articles, and are covered by the Copyright on those articles:
- KR Foster, LS Erdreich, JE Moulder: Weak electromagnetic fields and cancer in the context of risk assessment. Proc IEEE, 85:733-746, 1997.
- JE Moulder: Power-frequency fields and cancer. Crit Rev Biomed Eng 26:1-116, 1998.
- JE Moulder, LS Erdreich, RS Malyapa, J Merritt, WF Pickard, Vijayalaxmi: Cell phones and cancer: What is the evidence for a connection? Radiat. Res., 151:513-531, 1999.
- KR Foster, JE Moulder: Are mobile phones safe? IEEE Spectrum, August 2000, pp 23-28.
- KR Foster, JE Moulder: Mobiles et cancer, un vrai casse-tête. La Recherche 337:39-47, 2000.
- KR Foster, P Vecchia, JE Moulder: Effetti sulla salute dei telefoni mobili. AEI 87:36-41, 2000.
- KR Foster, PJ Riu, JE Moulder: Efectos de los teléfonos móviles en la salud: Nuevas evidencia. Mundo Electronico, February 2001, pp. 34-39.
- KR Foster, JE Moulder: Teléfonos móviles y cancer cerebral. Mundo Cientifico, Dec. 2000.
- JE Moulder: Radiaciones de Radiofrecuencias y Cancer: Efectos Biologicos y
Posibles Mecanismos. In: P. Gil-Loyzaga and A. Ubeda
Eds. , Ondas Electromagneticas y Salud, Informes Sanitarios,
Siglo XXI, No. 1, Madrid, Spain, pp: 287-336, 2002.
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