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This FAQ addresses the issue of whether base station transmitter/antennas for mobile phones (cellular phones, PCS phones), and other types of portable transceivers are a risk to human health.
Issues surrounding the phones (transceivers) themselves, including the regulation of radio-frequency (RF) energy emissions from the phones, are discussed only indirectly. For detailed discussions of whether RF energy from mobile phones is associated with cancer or other health risks see:
KR Foster and JE Moulder: Are mobile phones safe? IEEE
Spectrum, August 2000, pp 23-28.
(http://www.spectrum.ieee.org/publicfeature/aug00/prad.html)
Human Exposure to Radio Frequency and Microwave Radiation from Portable and
Mobile Telephones and Other Wireless Communication Devices. IEEE Eng Med Biol,
Jan/Feb 2001, pp 128-131.
(http://ewh.ieee.org/soc/embs/comar/phone.htm)
H Frumkin, A Jacobson et al: Cellular phones and risk of
brain tumors. CA Cancer J Clin 51:137-141, 2001.
(http://www.cancer.org/docroot/pub/content/pub_3_8x_environmental_carcinogens-cellular_phones_and_risk_of_brain_tumors.asp)
Mobile
telephones: an evaluation of health effects.
Health Council of the Netherlands, The Hague, 2002.
(http://www.gr.nl/pdf.php?ID=377)
Cell Phone
Facts: Consumer Information on Wireless Phones, Food and Drug Administration and
the Federal Communications Commission..
(http://www.fda.gov/cellphones/)
JD Boice and JK McLaughlin: Epidemiological studies of
cellular telephones and cancer risk -- A review. Stockholm, Swedish Radiation
Protection Authority, 2002.
(http://www.ssi.se/ssi_rapporter/pdf/ssi_rapp_2002_16.pdf)
NEW
Mobile Phones and Health 2004: Report by the Board of NRPB.
Documents of the NRPB 15:1-114, 2004.
(http://www.nrpb.org/publications/documents_of_nrpb/abstracts/absd15-5.htm)
NEW
ZJ Sienkiewicz and CI Kowalczuk: A Summary of Recent
Reports on Mobile Phones and Health (2000-2004). Chilton, National Radiological
Protection Board, 2005.
(http://www.nrpb.org/publications/w_series_reports/2005/nrpb_w65.htm)
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.
El documento "Preguntas y respuestas sobre antenas de telefonía móvil y salud humana" está disponible en español: http://www.mcw.edu/gcrc/cop/telefonos-moviles-salud/toc.html
Queste FAQ riguardanti "le antenne per telefonia mobile e i loro effetti sulla salute" sono disponibili in italiano all'indirizzo: http://space.tin.it/clubnet/albpales/Telefonia_mobile/toc-it.htm
An older version of this document is available in Chinese at: http://www.ym.edu.tw/rad/cbase/
This document is available in Japanese at: http://www.iftech.or.jp/cellular/health.html
There are two related FAQs:
Power Lines and Cancer FAQs
(
http://www.mcw.edu/gcrc/cop/powerlines-cancer-faq/toc.html)
Static Electromagnetic Fields and Cancer FAQs
(
http://www.mcw.edu/gcrc/cop/static-fields-cancer-faq/toc.html)
This FAQ was designed with Netscape v7.2 and for conformation with HTML 4.0 transitional.
Do mobile phone base station antennas produce radiation?
Are there safety guidelines for mobile phone base station antennas?
Is there a scientific basis for these RF energy safety guidelines?
Are all RF energy safety guidelines the same?
Does the U. S. have safety guidelines for mobile phone base stations?
NEW Can mobile phone base station antennas meet the safety guidelines?
What are some general siting criteria?
What are the differences 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?
What precautions need to be taken when working around mobile phone base station antennas?
How do you assess compliance with RF energy guidelines for mobile phone base stations?
The U. S. Environmental Protection Agency and the current RF energy safety guidelines.
What did an expert scientific panel in Canada say about the safety of mobile phone base stations.
What did an expert scientific panel in France say about the safety of mobile phone base stations.
What did an expert scientific panel in Australia say about the safety of mobile phone base stations.
Are there epidemiological studies showing that exposure to RF energy from base stations is safe?
NEW Geographic correlation studies
Microwaves and the US Embassy in Moscow
NEW Studies of exposure to mobile phone RF energy
NEW Reviews of the epidemiology
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 mobile phones or mobile phone base stations cause headaches?
Can RF energy produce biological effects?
Is there any replicated evidence that RF energy can cause cancer?
Is there any evidence that RF energy can cause miscarriages or birth defects?
What do the most recent scientific laboratory studies of RF energy and cancer show?
The 1997 report that exposure of mice to mobile phone RF energy causes lymphoma.
NEW Studies in which rodents were exposed to mobile phone RF energy for long periods of time.
Does the human body produce more RF energy than a person would get near a mobile phone base station?
Where can I get more information?
Who wrote these Questions and Answers?
v7.4, Mar/Apr 2005:
Governmental reports and academic reviews:
A review of the epidemiology of RF energy from the International Commission for Non-Ionizing Radiation Protection (ICNIRP) Standing Committee on Epidemiology [219] concluded that: "Results of these studies to date give no consistent or convincing evidence of a causal relation between RF exposure and any adverse health effect". See summary in Q16F.
Two new reports from the U.K. National Radiological Protection Board. One [217] is a review of mobile phones and health, and the other [229] is a review of reviews done by other groups. See excerpts in Q15C.
In 2003, Zwamborn et al [178] reported that exposure of human volunteers to base station RF energy caused decreased feelings of "well-being" and improvement on some cognitive function tests. A formal critique this study was done by the Health Council of the Netherlands [232]. See discussion in Q19C.
A review of the genotoxicity assays done with RF energy [224]. See excerpts in Q23C.
Epidemiology and experimental human studies:
In 1997, Dolk and colleagues [28] analyzed cancer rates in the area surrounding an FM/TV broadcast tower in the UK and found a decreasing incidence of adult leukemia with increasing distance from the antennas. In a 2001 follow-up report, Cooper and colleagues [216] reported that more recent cancer incidence data did not support the association of distance and adult leukemia incidence found in the original study. See discussion in Q16A.
Three new studies of exposure to human volunteers to mobile phone RF energy found no consistent evidence of effects [220, 222, 225].
Long-term and/or heavy users of mobile phones had slightly less brain cancer than expected [227]. See discussion in Q16C.
Exposure to human volunteers to mobile phone RF energy caused an increase in cerebral blood flow [231].
Animal studies:
Mobile phone RF energy had no effect on melatonin levels in rats [226].
Exposure of rats to RF energy produced inconsistent evidence of genotoxic injury to their bone marrow cells [223].
Exposure to rats to RF energy had no effect on anxiety responses [230].
Long-term exposure to mobile phone RF energy did not promote chemically-induced brain cancer in rats [228]. See discussion in Q23B.
Cellular studies:
Studies funded by the European Union (the REFLEX report) report some evidence from cellular studies that mobile phone RF energy might be genotoxic [221]. See Q23D.
Dosimetry and biophysical studies:
Measurements of RF energy in a large town in northern Italy found that radio/TV signals were generally stronger than mobile phone (base plus handset) signals, and that all measurements showed power densities well below even the Italian safety standard [215].
Additions and changes in 2004:
Governmental reports and academic reviews:
A review of the mobile phone base station controversy in France [214].
A draft of new occupational exposure guidelines from the European Union [212] which appear to be nearly identical to the ICNIRP [4] exposure guidelines.
A review [206] of the issue of whether modulation should be considered as a factor of potential biological importance in assessment of the risk of RF energy emitted by communications systems is discussed in Q17.
A statement [209] about the safety of mobile phones and their base stations was released by expert groups in Denmark, Finland, Iceland, Norway and Sweden; it is covered in a new Q15I.
A report on a 2003 workshop that was held to discuss research on the effects of RF energy on the blood-brain barrier [211].
An academic review on mobile phones and cancer [202] which concludes that the current evidence indicates that "long term exposure to emissions from mobile phones may lead to a small to moderate increased risk of developing certain types of cancer."
A report on the biological effects of modulated RF energy from the US National Council on Radiation Protection and Measurements (NCRP) [201] is summarized in Q17..
A review of the scientific evidence underlying exposure limits for RF energy from the UK National Radiological Protection Board [200].
Epidemiology and experimental human studies:
A report that long-term use of analog phones was associated with an increase in the incidence of acoustic neuromas. The increase was not statistically significant, but the acoustic neuromas that occurred in the long-term users occurred disproportionately on the side of the head where they reported using their mobile phones [210]. NEW A later study by the same group [227] suggests that the disproportionate reports of mobile phone use on the side of the head where the tumors occurred is a case of "recall bias"; see discussion in Q16C.
Exposure of human volunteers to RF energy from GSM mobile phones impaired their performance on cognitive performance tests [207].
Use of mobile phones and/or cordless phones was not associated with an increased risk of salivary gland tumors [208].
The Koivisto group reported [205] that they could not replicate their own earlier finding of RF energy effects on human short-term memory.
Cancer rates were reported to be elevated around Korean AM radio broadcast antennas [204].
Exposure of human volunteers to mobile phone RF energy had no effect on blood pressure or heart rate [198].
Exposure to mobile phone RF energy led to decreased reaction times in human volunteers [197].
Use of mobile phones in Denmark was not associated with an increased rate of benign brain tumors (acoustic neuromas) [192].
Krause et al [188] report that they cannot replicate their own earlier studies in which they had reported that human volunteers who were exposed to RF from a GSM phone showed changes in brain activity (EEG) and performance on memory tasks.
Animal studies:
Two years of exposure of rats to 1600 MHz RF energy at 0.16 or 1.6 W/kg had no effects on cancer incidence, general health or survival [203].
Exposure of pregnant mice and their offspring to pulsed RF energy did not cause mutations [199].
Exposure of rats to 2450 MHz pulsed RF energy at 1.2 W/kg did not cause DNA damage in their brain cells [193].
Cobb et al [189] report that they cannot replicate a 1994 study in which Lai and colleagues reported that exposure of rats to low-level RF energy caused changes in the rats' ability to learn a maze.
Cellular studies:
Exposure of mammalian cells to analog or digital mobile phone signals at 0.03-3.2 W/kg did not cause apoptosis or DNA strand breaks [191].
Exposure of mammalian cells to 2450 MHz RF energy at 1.9 W/kg did not cause DNA strand breaks [190].
Dosimetry and biophysical studies:
A discussion of the claim the human body produce more RF energy than a person would get near a mobile phone base station is discussed in a new Q24.
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 (RF) energy (that's how they communicate), and they expose people near them to RF energy. However, because both the phones and the base stations are low power (short range), the RF energy 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 energy; 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 energy.
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 RF energy to very small volumes of the user's body [61]. 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 mobile phones see:
the 1999 and 2000 reviews by Moulder and colleagues [64, 86]
the 2000-2001 review by the Royal Society of Canada [68]
the 2000 report of the UK Independent Expert Group on Mobile Phones (the "Stewart Commission") [84]
the 2001 IEEE position paper [21]
the 2001 review from the World Health Organization [109]
the 2001 review from American Cancer Society [107]
the constantly updated US FCC/FDA website [128]
the 2002 report from the Health Council of the Netherlands [124]
the 2004 review by Kundi [202]
NEW the reviews from the UK NRPB in 2003-2005 [187, 200, 217, 229]
3) Do the differences between cell phones, PCS phones, analog phones, digital phones and other types of mobile phones matter when evaluating the potential impacts of base station antennas on human health?
No. There are many technical differences between different types of "mobile" phones [1, also see international note 1]; but for evaluation of possible health hazards, the only distinction that matters is that they operate at slightly different frequencies. The RF energy from some base stations (e.g., those for the older 800 MHz mobile phones used in the U.S.) may be absorbed by humans somewhat more than the RF energy from other types of base stations (e.g., those for the 1800-2000 MHz "PCS" phones used in the U.S.) [18]. 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 energy from some antennas (particularly FM and VHF-TV broadcast antennas) are absorbed more by humans than the RF energy 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 800-1200 ft or 250-400 meters).
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) energy; that's how they work. This RF energy is "non-ionizing", and its biological effects are fundamentally different from the "ionizing" radiation produced by x-ray machines [see Q6].
This RF energy can also be called microwaves, radiowaves, RF radiation (RFR) or RF emissions. For the discussion of health effects the distinction between radiowaves and microwaves is semantic; and the term "RF energy" or just "RF" is used in this document for all frequencies between 3 kHz and 300 GHz.
6) Is the RF energy from mobile phone base station antennas similar to ionizing radiations such as X-rays?
No. The interaction of electromagnetic energy with biological material (cells, laboratory animals or humans) depends on the frequency of the source [41]. X-rays, RF energy and "EMF" from power lines are all produced by electromagnetic sources, but the frequencies of their sources are very different. 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 (1 MHz = 1,000,000 Hz), FM radio has a frequency of around 100 MHz, microwave ovens have a frequency of 2450 MHz, and X-rays have frequencies above one million MHz. Cellular (mobile) phones operate at a variety of frequencies between about 800 and 2200 MHz [also see international note 1].
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 those used by mobile phones and their base stations, the energy of the particles is much too low to break chemical bonds. Thus RF energy 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 RF energy [41].
The Electromagnetic Spectrum |
7) Is the RF energy 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 energy produces biological effects [2, 41]. There appears to be no similarity between the biological effects of power line "EMF" and the biological effects of RF energy.
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 energy 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) [3, 185b], the International Commission on Non-Ionizing Radiation Protection (ICNIRP) [4], and the National Council on Radiation Protection and Measurements (NCRP) [5].
These RF standards are expressed in "plane wave power density", which is measured in mW/cm-sq (milliwatts per square centimeter) [6, 185b]. For base stations that operate in the 1800-2000 MHz range (for example, PCS base stations in the USA), the 1999 ANSI/IEEE exposure standard for the general public is 1.2 mW/cm-sq. For antennas that operate around 900 MHz (for example, base stations for analog phones in the USA), the ANSI/IEEE exposure standard for the general public is 0.57 mW/cm-sq [7]. The ICNIRP standards are slightly lower and the NCRP standards are essentially identical [8].
In 1996 the U.S. Federal Communications Commission (FCC) released RF guidelines for the frequencies and devices they regulate, including mobile phone base station antennas [9]. The FCC standards for mobile phone base station antennas are essentially identical to the ANSI/IEEE standard [3].
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 [11].
Also see international note 10 and Erdreich and Klauenberg [108].
9) Is there a scientific basis for these RF energy safety guidelines?
Yes. When scientists have examined all the published literature on the biological effects of RF energy they found that the literature agreed on a number of key points [see 3, 4, 5, 41, 92, 61, 62, 64, 65, 68, 108, 143, 151, 168, 170, 185a, 195, 200, 209, 217, 219, 229 for details]:
Exposure to RF energy can be hazardous if the exposure is sufficiently intense. Possible injuries include cataracts [185i], skin burns, deep burns, heat exhaustion [185c] and heat stroke [185c]. See Reeves [83] and Adair and Black [185c] for a discussion of the known effects of overexposure to RF energy in humans.
Biological effects of RF energy depend on the rate of energy absorption [6]; and within a broad range of frequencies (1 to 10,000 MHz), the frequency matters very little.
Biological effects of RF energy are proportional to the rate of energy absorption; and the duration of exposure matters very little [65].
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) [12].
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 [3, 185b] and ICNIRP [4]:
They reviewed the scientific literature to find the lowest energy absorption rate (SAR) that consistently showed potentially-harmful biological effects.
To establish occupational exposure guidelines, they applied a 10-fold safety margin to that SAR.
They then applied an additional 5-fold safety margin to establish guidelines for continuous exposure of the general public.
Finally, detailed engineering and physics studies were done to establish the relationship of power density, which can be routinely measured, to the energy absorption rate (SAR), which really matters [6].
The result was a highly conservative public exposure guideline that was set at a level that is only 2% of the level where potentially-harmful biological effects have actually been demonstrated.
10) Are all RF energy safety guidelines the same?
No. There are differences between the standards. ANSI/IEEE, ICNIRP, NCRP and FCC all use the same general approach to setting safety guidelines. However, there are differences in the physics (dosimetry) models used by the different groups, and hence there are slight differences in the final numbers [13, 108, 185b].
A number of countries have their own regulations for public exposure to RF energy from mobile phone base station antennas. While most of these regulation follow the same patterns and rationales used by ANSI/IEEE [3] and ICNIRP [4], they do differ. See International note 10 and Erdreich and Klauenberg [108] for details.
Some countries (e.g., Switzerland and Italy) have adopted regulations for public exposure to RF energy that are dramatically lower than the ANSI/IEEE [3] and ICNIRP [4] guidelines. In general these lower numbers are based on political considerations rather than on different interpretations of the science.
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 1982 version of the IEEE/ANSI standard. In 1996 the FCC adopted a new standard [9] that was based on a combination of the 1992 ANSI/IEEE [3, 185b] and the 1986 NCRP guidelines [5].
The 1996 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 now applies to all mobile phone base stations (and all other broadcast antennas), regardless of when they were licensed.
The FCC power-density standards described above apply to whole-body public exposure to RF energy 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 energy exposure see FCC OET Bulletin 56 [89], the FCC guideline itself [9], Foster and Moulder [86], Tell [77], and the documents references in Q2.
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.
NEW A mobile phone base station antenna, mounted 10 meters (33 ft) above publicly-accessible areas and operated at the maximum intensity, might produce a power density as high as 0.01 mW/cm-sq in publicly-accessible areas near the antenna site; but power densities in publicly-accessible areas will more often be in the 0.00001 to 0.0005 mW/cm-sq range [45, 60, 81, 85, 215]. 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 should be less than 5% of the FCC guidelines at all heights and at all distances of more than 40 meters (130 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 [42, 85].
Petersen et al [60] measured power densities around mobile phone base stations. The measurements were for antennas radiating 1600 W ERP (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 and ICNIRP standards for public exposure.
In 1999 in Vancouver Canada, Thansandote et al [81] measured RF levels in five schools, three of which had base stations on them or near them. All schools met Canadian, US and international RF standards by a wide margin. The maximum readings are shown in the following table.
| School | Base Station Location | Maximum RF Level |
| 1 | digital (PCS) base station across street | 0.00016 mW/cm-sq |
| 2 | analog base station on roof | 0.0026 mW/cm-sq |
| 3 | analog base station across street | 0.00022 mW/cm-sq |
| 4 and 5 | no antennas nearby | less than 0.00001 mW/cm-sq |
| Canadian Standard | less than 0.57 mW/cm-sq |
In 2000, the U.K. National Radiation Protection Board [85] measured RF energy levels at 118 publicly-accessible sites around 17 mobile 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 RF energy from all sources (mobile 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.
RF Energy 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. [85]. |
In 2001, the Radiocommunications Agency of the UK Department of Trade and Industry measured RF energy levels at 100 schools that had mobile phone base stations on (or near) them. The maximum RF level measured at any school was less than 1% of the ICNIRP standard [4] for public areas; the maximum in most schools was less than 0.05% of that standard. The results of this audit are summarized in the figure below and the details are on the web at: http://www.radio.gov.uk/topics/mpsafety/school-audit/audit.htm.
RF Energy Levels in Schools Near Mobile Phone Base
Stations in the UK
|
| Maximum RF energy levels (in comparison to the ICNIRP standard for public areas) in UK schools that have mobile phone base stations near them. Adapted from . http://www.radio.gov.uk/topics/mpsafety/school-audit/audit.htm/. |
A 2000 survey of GSM base stations by the Australian
Radiation Protection and Nuclear Safety Agency found that public exposures to RF
energy were less than 0.1% of their standard [169].
The highest exposure level they found was less than 0.0002 mW/cm-sq (less than
0.01% of the ICNIRP public exposure guidelines), and the average exposure level
was less than 0.0001 mW/cm-sq. At most of the 13 sites they measured, there were
other types of RF signals that were more powerful than the base station signal
(AM radio was more powerful in 12 cases, FM radio in 6 cases, and TV in 3
cases). At all sites measured the total RF energy from all sources combined
(mobile phone base stations, AM radio, FM radio, VHF TV, UHF TV, paging) was
less than 0.1% of the Australian (or the ICNIRP or FCC) RF safety guidelines.
The Australian report is on line at:
http://www.arpansa.gov.au/pubs/eme_comitee/rfrep129.pdf
NEW In 2001, Anglesio et al [215] reported that measurements of RF energy in buildings in a large town in northern Italy found that radio/TV signals were generally stronger than mobile phone (base plus handset) signals, and that all measurements showed power densities far below even the Italian safety standard (0.01 mW/cm-sq). The peak level was less than 0.003 mW/cm-sq.
The relationship between the RF levels required to produce known biological effects, the RF levels specified in the FCC, IEEE and ICNIRP 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 safety guidelines, and the RF power density levels actually measured 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 mobile 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 site 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 8 meters/25 feet (horizontal) of the radiating surface(s) of the antennas themselves [14]. This could arise for antennas mounted on or near the roofs of buildings. For example, Petersen et al [60] found that 2-3 feet (1 meter) from a roof-top antenna radiating 1600 W ERP, the power density was as high as 2 mW/cm-sq (compared to the ANSI/IEEE [3] public exposure standard of 0.57-1.2 mW/cm-sq).
For antennas mounted on towers, it is somewhat difficult to imagine a situation that would not meetthe safety guidelines. However, there are reports (principally from outside North America and Europe) of mobile phone base station antennas facing directly at nearby buildings. Whether these antennas would meet FCC, ANSI/IEEE or ICNIRP safety guidelines would depend on the ERP, the exact geometry and the degree of shielding provided by the building.
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 1999 ANSI/IEEE [3] or FCC [Q11] guidelines for public exposure. As a general rule, the uncontrolled (public) exposure guideline cannot be exceeded more than 8 meters (25 feet) from the radiating surface of the antenna [14].
If there are areas accessible to workers that exceed the 1999 ANSI/IEEE [3] or FCC [Q11] 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 8 meters (25 feet) from the radiating surface of the antenna [14].
If there are areas that exceed the 1999 ANSI/IEEE [3] or FCC [Q11] 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 probably be limited to areas within 3 meters (10 feet) of the antennas [14].
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 [9] require detailed calculations and/or measurement of RF energy for some types of base stations [15]. In June 2003, the FCC proposed some significant changes in these rules (see note 15).
Problems, when they exist, are generally confined to:
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). Note that the occupation safety standards for RF energy apply only to workers with appropriate RF energy safety training.
Towers that are placed very close to, and lower than, nearby buildings.
14B) What are the differences between a high-gain antenna and a low-gain antenna?
There are many different types of base station antennas, and the RF energy 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. Depending on the antenna gain, a 20-50 W base station transmitter could produce an ERP of anywhere from about 50 watts to over 1000 watts.
The concept of "gain" and "ERP" are best explained by analogy to light bulbs. Compare a regular 100 W light bulb to a 25 W spot light. The spot light has less total power than the regular light, but is much brighter when you are in its beam and much weaker when you are outside its beam. A mobile phone base antenna (particularly a high-gain sector antenna) is like the spot light, and ERP is equivalent to the effective 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 [88].
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 mobile phone base stations, the pattern can look like this:
RF Energy Levels 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 Energy Levels 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.
14E) Is it safe to live or work 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).
Even a worst-case calculation predicts that power density on the floor below an antenna will meet all current RF safety guidelines [43].
Actual measurements in top floor apartments and corridors confirm the power density is far below all current RF safety guidelines [43].
14F) Are use restrictions or "set-backs" required around mobile phone base station antenna sites and what is the "minimum safe distance"?
RF safety guidelines do not require either setbacks or use restrictions around mobile phone base station antenna sites, since power levels on the ground should not (by definition) be 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 [128] as follows:
"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 (or building or structure) 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 energy safety guidelines, so the concept of a "minimum 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 [85], the ground level power density does not drop with distance in any regular manner until you get 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 85).
The antenna height, the antenna power and the antenna pattern are much bigger factors in determining ground level exposure to RF energy than the horizontal distance from a base station.
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 thus limit the number of users that can connect.
14G) What precautions need to be taken when working around mobile phone base station antennas?
A detailed discussion of RF energy occupational safety guidelines is beyond the scope of this FAQ.
In a detailed discussion of guidelines for telecommunications antenna installation, Tell [77] makes the following recommendations:
Specific Antenna Installation Guidelines (from Tell [77])
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 RF Energy Exposure (from Tell [77])
Individuals working at antenna sites should be informed about the presence of RF energy, 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]
RF energy levels at a site should be modeled before the site is built.
RF energy levels at a site should be 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 [RF energy] exposures low, maintain a 3-4 ft [1-1.2 m] distance from any [telecommunications] antenna." [77]
"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 [96] 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 RF energy 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 energy. Measurements require access to sophisticated and expensive equipment. Calculations require detailed knowledge about the power, antenna pattern and geometry of each antenna at a site.
Nothing as simple as distance from an antenna site is adequate for assessing compliance or estimating exposure levels [85, 113]. As discussed and illustrated in Q12, RF energy 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 are 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. See Barbiroli et al [162] for an example of how exact calculations can be made if all relevant technical specifications are known.
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 energy at a typical site (see Mann et al [85] and Line et al [169]).
For a technical discussion of measurement techniques and instrumentation see Mann et al [85], NCRP Report No. 119 [88] and Line et al [169].
15) What are other scientists, scientific organizations and governmental review groups saying about RF energy and the safety of mobile phones base stations?
This section will deal with what other scientists, scientific organizations and governmental review groups are saying about RF energy safety and mobile phone base stations. Occasionally this section will also deal with reports on RF energy safety and mobile phones base stations that appear in the mass media.
15A) The U. S. Environmental Protection Agency and the current RF energy safety guidelines.
The EPA asked the FCC to adopt parts of the 1986 NCRP guidelines [5] rather than the entire 1999 ANSI/IEEE guidelines [3]. This the FCC did [9], and EPA has formally endorsed the FCC safety guidelines.
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) Claims on British, American and French TV that there is new data suggesting that mobile phones might cause cancer.
In the summer and fall of 1999 (and repeated in 2000 and possibly in 2001), programs on British, American and French TV claimed that there was new data suggesting that RF energy from mobile phones could cause injury to humans. Four sources of "new" information were generally cited:
An epidemiology study of mobile phone use and brain cancer by Hardell et al [69]. See Q16E for a detailed discussion of this study.
A 1999 report by Preece et al [66] that exposure of human volunteers to mobile phone RF energy might decrease reaction times.
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 literature [91,127]. The published version reports no significant association between malignant [91] or benign [127] brain cancer and the use of hand-held mobile phones. See further discussion of the study in Q16E.
The WTR genotoxicity study was presented at a meeting in March of 1999 [71, 72]. Parts of this WTR study were published in early 2002 [121]. The published version [121] reports that RF energy 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 [97], Bisht et al [130], McNamee et al [146, 147] and Koyama et al [186] have reported that they cannot replicate the micronucleus findings. The authors of the WTR genotoxicity study speculate that their reported effect on micronucleus formation may be due to heating.
15C) What did expert scientific panels in the United Kingdom say about the safety of mobile phone base stations.
In 2000, a special committee in the U.K., the Independent Expert Group on Mobile Phones (IEGMP, also known as the "Stewart Commission") issued a report on mobile phone safety issues [84]. The full text is available at: http://www.iegmp.org.uk/report/text.htm.
NEW Follow-up
reports were issued in 2003 [187],
2004 [200,
217]
and 2005 [229].
The full text of the 2003 report [187]
is available at:
http://www.nrpb.org/publications/documents_of_nrpb/abstracts/absd14-2.htm
the 2004 reports [200,
217]
are at:
www.nrpb.org/publications/documents_of_nrpb/abstracts/absd15-3.htm
and
www.nrpb.org/publications/documents_of_nrpb/abstracts/absd15-5.htm
and the 2005 report [229]
is at:
http://www.nrpb.org/publications/w_series_reports/2005/nrpb_w65.htm
On the general issue of RF energy safety, the Expert Group concluded in 2000 that [84]:
"The balance of evidence to date suggests that exposures to RF energy below NRPB and ICNIRP [4] guidelines do not cause adverse health effects to the general population..."
In 2003, the U.K. Advisory Group on Non-Ionizing Radiation [187] concluded that:
"In aggregate the research published since the [2000] IEGMP report does not give cause for concern. The weight of evidence now available does not suggest that there are adverse health effects from exposures to RF fields below guideline levels, but the published research on RF exposures and health has limitations, and mobile phones have only been in widespread use for a relatively short time. The possibility therefore remains open that there could be health effects from exposure to RF fields below guideline levels; hence continued research is needed."
NEW In 2004, the NRPB [217] reported that:
"The widespread development in the use of mobile phones world-wide has not been accompanied by associated, clearly established increases in adverse health effects. Within the UK, there is a lack of hard information showing that the mobile phone systems in use are damaging to health. It is important to emphasize this crucial point."
With respect to mobile phone base stations, the 2000 Expert Group concluded that [84]:
"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."
In 2003, the U.K. Advisory Group on Non-Ionizing Radiation [187] concluded that:
"Exposure levels from living near to mobile phone base stations are extremely low, and the overall evidence indicates that they are unlikely to pose a risk to health."
NEW In 2004, the NRPB [217] reported that:
"The [Office of Communications] measurements indicate that exposures of the public from macrocell base stations are small fractions of exposure guidelines... Similar conclusions on exposure levels have been reached by NRPB from surveys of around 60 base station sites. Exposures in proximity to picocells have been found to be no more than a few per cent of guidelines for the public."
With respect to RF energy and cancer, the the U.K. Advisory Group on Non-Ionizing Radiation [187] concluded that:
"The biological evidence suggests that RF fields do not cause mutation or initiate or promote tumour formation, and the epidemiological data overall do not suggest causal associations between exposures to RF fields, in particular from mobile phone use, and the risk of cancer,"
NEW The 2005 report from the NRPB [229] is a review of 26 reviews done by other countries and scientific groups. It concludes that:
"Most of the 26 reports examined here have reached similar conclusions... Overall the reports acknowledge that exposure to low level RF fields may cause a variety of subtle biological effects... but the possibility of exposure causing adverse health effects remains unproven... Further, these reports stress that very low level exposures, typical of base stations, are extremely unlikely to cause any effects on biophysical grounds, whereas localized exposures, typical of those from mobile phones, may induce effects as a result of mild heating of superficial tissues close to the head."
15D) What did an expert scientific panel in Canada say about the safety of mobile phone base stations.
An Expert Panel assembled by the Royal Society of Canada issued a report on mobile phone safety in 1999 [68]. The report is online at: http://www.rsc.ca/english/RFreport.pdf.
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."
15E) What did expert scientific panels in the United States say about the safety of mobile phone base stations.
In 2001 the Institute of Electrical and Electronics Engineers (IEEE) published a statement on mobile phone base stations [22]. The report is on-line at: http://ewh.ieee.org/soc/embs/comar/base.htm.
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"
In a website (http://www.fda.gov/cellphones/) that went on-line in May 2002, the US Food and Drug Administration and the Federal Communications Commission state that:
"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..."
15F) What did an expert scientific panel in the Netherlands say about the safety of mobile phone base stations.
In 2002, the Health Council of the Netherlands issued a report on the safety of mobile phones [124]. The report is on-line at: http://www.gr.nl/pdf.php?ID=377.
On the general issue of mobile phone handset 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 [125] 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."
15G) What did an expert scientific panel in France say about the safety of mobile phone base stations.
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) [118]. An English-language summary is on-line at: http://www.sante.gouv.fr/htm/dossiers/telephon_mobil/conclus_uk.htm.
On the general issue of mobile phone handset 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) What did an expert scientific panel in Australia say about the safety of mobile phone base stations.
In a supplement to their 2002 RF energy protection standard [168] the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) discussed the safety of mobile phone base stations:
"Radiofrequency radiation (RFR) from mobile phone towers makes only a minor contribution to the total environmental RFR that arises primarily from other communications sources. Depending on location the RFR from mobile phone towers is generally less than 3% of all RFR from other contributing sources including AM and FM radio, television, paging systems and emergency services... Further, the exposure levels from all combined radiofrequency sources as measured adjacent to the mobile phone towers are generally much less than 2 microwatts per square centimeter [0.002 mW/cm-sq]. Such RFR levels are below 1% of the maximum allowable public exposure levels."
Elsewhere in that document ARPANSA discussed safety standards for public exposure to RF energy:
"Significant safety factors are incorporated into the exposure limits -- that is, the limits are set well below the level at which adverse health effects are known to occur. Current data does not establish the existence of adverse heath effects for exposure levels below the limits of the ARPANSA."
Note that with respect to public exposure to RF energy from mobile phone base stations the Australian standard is largely (if not completely) in agreement with the ICNIRP Guidelines.
15I) What did expert groups in Denmark, Finland, Iceland, Norway and Sweden say about the safety of mobile phone base stations.
In 2004, the Danish National Board of Health, the Radiation and Nuclear Safety Authority of Finland, the Icelandic Radiation Protection Institute, the Norwegian Radiation Protection Authority and Swedish Radiation Protection Authority issued a joint statement on "Mobile Telephony and Health" [209]. The statement is on-line at: http://www.ssi.se/ickejoniserande_stralning/mobiltele/NordicMobilPress2004.pdf
"The Nordic authorities agree that there is no scientific evidence for any adverse health effects from mobile telecommunication systems, neither from the base stations nor from the handsets, below the basic restrictions and reference values recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). However, certain knowledge gaps exist that justifies more research in this field. There are a number of published reports suggesting that biological effects may occur at exposure levels below the ICNIRP guidelines. These studies need to be reproduced and the scientific progress in these fields of research should be followed carefully. In this context, however, it is important to note that biological effects do not necessarily imply health hazard."
"The exposure to the general public from base stations is extremely low, normally 100 to 10 000 times lower than the ICNIRP guidelines and very much lower than the exposure from the handsets."
"It is uncertain if children and young people are more sensitive than adults to electromagnetic fields from mobile telephony, very few direct studies of this subject have been performed. A recent compilation by the Health Council of the Netherlands concludes that there is no scientific evidence that children are more sensitive to radio frequency radiation than adults and that no special restrictions for children are needed."
16) Are there epidemiological studies showing that exposure to RF energy from base stations is safe?
Yes and no. While there have been no epidemiology studies of cancer and mobile phone base stations, there have been epidemiology studies of cancer and other types of exposure to RF energy. For summaries, see:
the 2002 review by Boice and McLaughlin [143];
the 2003 review by Elwood [185e];
the 2003 review by Breckenkamp et al [194];
the 2003 review by the Swedish Radiation Protection Authority [195];
the 2004 review by ICNIRP [219].
Epidemiology studies of RF energy from base stations have generally been concluded to be "infeasible, as there is no possibility to estimate individual exposure accurately enough" [138].
In general, epidemiology studies of RF energy 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 RF energy
"cancer cluster" studies
studies of cancer in people with military or occupational exposure to RF energy
users of hand-held mobile phones
16A) Geographic correlation studies
Geographic correlation studies estimate the strength of RF energy 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 generally used for determining causality.
The geographical correlation studies done to date show no consistent relationship between exposure to RF energy and either adult of childhood cancer. See Elwood [63] for a detailed discussion of the earlier geographic correlation studies. The best known geographical correlation studies are those of cancer in people living near TV or radio broadcast towers.
1996 and 2004: Hocking and colleagues [23] compared municipalities "near TV towers" to those further away. No RF energy exposures were actually measured, no other sources of exposure to RF are taken into account, and the study is based on only a single metropolitan area. The authors reported an elevated incidence of total leukemia and childhood leukemia, but no increase in total brain tumor incidence or childhood brain tumor incidence. In 2003, they also reported decreased survival in these childhood leukemia cases [213].
1998: McKenzie and colleagues [46] repeated the Hocking study [23]. They looked at the same area, and at the same time period; but they made more precise estimates of the exposure to RF energy 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. The increased incidence reported by Hocking et al [23] was found to have been based on data from a single area, and to have resulted largely from cases diagnosed before 24-hr TV transmission was introduced at most of the stations.
1997: Dolk and colleagues [28] 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.
1997: Because of the above finding, Dolk and colleagues [29] 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 [28] or by Hocking et al [23] in Australia.
NEW 2001: In a follow-up to the first 1997 Dolk et al study [28], Cooper et al [216] reported that more recent cancer incidence data did not support the association of distance and adult leukemia incidence reported at Sutton Coldfield.
2002: Michelozzi et al [135] reported that the incidence of childhood leukemia was elevated within 6 km of Vatican Radio (31 transmitters at 4-44 kHz and 0.5-1.6 MHz, with power of up to 600,000 W). The authors also report elevated leukemia in adult men residing near the transmitters, but not in adult women. Interpretation of this reported cancer cluster is limited by the small numbers and by the use of distance as a surrogate of exposure.
2002: Hallberg and Johansson [134] speculated that the increase in melanoma seen in Sweden (and industrialized countries) since 1960 is due to exposure to FM radio broadcasting.
2004: Park et al [204] reported that overall cancer death rates were slightly elevated among people who died in "administrative units" that contained AM radio broadcast antennas. The overall association is weak and is seen only in males. No specific types of cancer are elevated, and there is no trend towards increased cancer death rates with increasing broadcast power. The authors note that "In the Korean culture, most people tend to return to their hometown when they die"; so that the "administrative units" where people die will frequently not reflect where they lived (and what they were exposed to) before they developed cancer.
16B) 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 have not generally been followed in studies of RF energy, and the reports of "cancer clusters" are of essentially no value in determining whether exposure to RF energy is a cause of cancer (see Elwood [63] for details of these studies).
16C) Occupational exposure studies
There are five epidemiological studies of occupational exposure to RF energy that are generally considered to have acceptable design and analysis, adequate sample size, and sufficient follow-up time: Robinette et al [52], Hill [53], Milham [54], Morgan et al [78] and Groves et al [126]. These five studies do not show any consistent associations between exposure to RF energy and either cancer in general or any specific kind of cancer.
The other studies of acceptable design (Lilienfeld et al [55 and Q16D], Lagorio et al [56], Muhm [57], Tynes et al [58], Grayson et al [27], and Thomas et al [74]) have more limitations in exposure assessment, case ascertainment, or follow-up time; but they also do not suggest that RF energy exposure increases the risk of either cancer in general or any specific kind of cancer.
Recent major occupational studies of RF energy exposure include:
2000: Morgan and colleagues [78] 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 energy exposure no elevation in rates of brain cancer, leukemia and lymphoma were found. Actual peak and/or average RF energy exposure levels are not known.
2002: Groves and colleagues [126] reported that exposure to RF energy from US Navy radar during the Korean War was 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 [52].
16D) Microwaves and the US Embassy in Moscow
There have been claims (by Goldsmith [24], for example) that microwave exposures at the US Embassy in Moscow caused cancer and other injuries to people working there. This exposure to RF energy 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 [