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. For detailed discussions of the evidence that RF radiation from mobile phones is associated with cancer or other health risks see:
  • JE Moulder et al: Cell Phones and Cancer: What Is the Evidence for a Connection? Radiation Research 151(5):513-531, May 1999. (http://www.radres.org/toc99.htm#may99)
  • 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, A COMAR Technical Information Statement. IEEE Eng Med Biol, Jan/Feb 2001, pp 128-131. (http://www.seas.upenn.edu:8080/~kfoster/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/eprise/main/docroot/PUB/content/PUB_3_8X_Environmental_Carcinogens-Cellular_Phones_and_Risk_of_Brain_Tumors)
  • Research and regulatory efforts on mobile phone health issues (GAO-01-545). US General Accounting Office, Washington, D.C., 2001. (http://www.gao.gov/new.items/d01545.pdf).
  • Mobile telephones: an evaluation of health effects. Health Council of the Netherlands, The Hague, 2002.
    (http://www.gr.nl/OVERIG/PDF/02@01E.PDF)
  • Cell Phone Facts: Consumer Information on Wireless Phones, Food and Drug Administration and the Federal Communications Commission: 2000..
    (http://www.fda.gov/cellphones/)
• 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
  • 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 Navigator v4.78 and for conformation with HTML 4.0 transitional.

1. What are mobile phone base stations; and are there health hazards associated with living, working, playing, or going to school near one?
2. Are scientists seriously concerned about possible health risks from mobile phone base station antennas?
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?
4. 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?
5. Do mobile phone base station antennas produce radiation?
6. Is the non-ionizing radiation (radio-frequency radiations) from mobile phone base station antennas similar to ionizing radiations such as X-rays?
7. Is the radio-frequency radiation from mobile phone base station antennas similar to the "EMF" produced by power lines?
8. Are there safety guidelines for mobile phone base station antennas?
9. Is there a scientific basis for these radiofrequency radiation safety guidelines?
10. Are all the safety guidelines the same?
11. Does the U. S. have safety guidelines for mobile phone base stations?
12. Can mobile phone base station antennas meet the safety guidelines?
13. Are there circumstances where mobile phone base station antennas could fail to meet the safety guidelines?
14. What siting criteria are required to ensure that a mobile phone base station antenna will meet safety guidelines?
    1. What are some general siting criteria?
    2. What are the difference between a high-gain antenna and a low-gain antenna?
    3. What do the phrases "antenna gain", "transmitter power" and "effective radiated power (ERP)" mean?
    4. What is the difference between the RF patterns for high-gain and low-gain antennas?
    5. Is it safe to live on the top floor of a building that has a mobile phone base station antenna on it?
    6. Are use restrictions or "set-backs" required around mobile phone base station antenna sites and what is the "minimum safe distance"?
    7. What precautions need to be taken when working around mobile phone base station antennas?
    8. How do you assess compliance with radio-frequency radiation guidelines for mobile phone base stations?
15. Does everyone agree with the current RF safety guidelines?
    1. Does the U. S. Environmental Protection Agency think that the current safety guidelines for mobile (cellular) phones are adequate?
    2. Has an Australian group claimed that there is evidence that living near TV broadcast towers causes an increase in childhood leukemia?
    3. Has an Israeli epidemiologist claimed that there is evidence that low-level RF exposure causes a variety of health effects?
    4. Has a British group reported excess leukemia and lymphoma around a high-power FM/TV broadcast antenna?
    5. Has a University of Washington (Seattle, U.S.A) researcher claimed that there is evidence that RF exposure from base stations is hazardous?
    6. What about the claims on British, American and French TV that there is new data suggesting that cell phones might cause cancer?
    7. What have various expert scientific panels (UK, US, Canada, Netherlands) said about the safety of mobile phone base stations?
    8. Did microwave irradiation of the US Embassy in Moscow cause cancer or other injuries to people working there?
16. Are there epidemiological studies showing that RF exposure from base stations is safe?
17. Could modulated RF radiation produce different effects than the continuous-wave (CW) RF radiation used in many laboratory studies?
18. Are there groups (such as children or the elderly) that are more sensitive to the effects of radio-frequency radiations?
19. Will mobile phone base station antennas affect heart pacemakers, cause headaches, etc?
    1. Will mobile phone base station antennas affect medical devices such as cardiac pacemakers?
    2. Do cell phones or cell phone base stations cause headaches?
    3. Does radio-frequency radiation from cell phones or cell phone base stations cause physiological or behavioral changes?
20. Can radio-frequency radiation produce biological effects?
21. Is there any replicated evidence that radio-frequency radiation can cause cancer?
22. Is there any evidence that radio-frequency radiation can cause miscarriages or birth defects?
23. What do the most recent scientific laboratory studies of RF radiation and cancer show?
    1. What about the report that exposure of mice to mobile phone RF radiation causes lymphoma?
    2. Has anyone else exposed rodents to mobile phone RF radiation to see if they got cancer?
    3. What about the report that exposure of mice to mobile phone RF radiation causes damage to the DNA in their brain cells?
24. Where can I get more information?
25. Who wrote these Questions and Answers?

What's New?

• [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 [185] and base stations [186].
• A new US government website on the safety and regulation of mobile phone and mobile phone base stations [189].
• A new French report on the safety and regulation of mobile phone and mobile phone base stations [179].
• [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 [178].
• A report that phase-modulated RF radiation was genotoxic to human cells, but that a continuous wave signal was not [180].
• A report that exposure of rats to mobile phone RF radiation does not promote chemically-induced breast cancer [181].
• 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 [182].
• A report that mobile phone RF radiation did not cause a certain type of genotoxic injury (micronucleus formation) in mammalian cells [191].
• 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 [190].
• A report that exposure of human volunteers to RF radiation from mobile phones improved their performance on tests for "attention" [183].
• A report that head-only exposure of rats to mobile phone RF radiation rat had no effect on learning [184].
• A report that use of mobile phones is not associated with an increased risk of acoustic neuromas (a benign brain tumor) [188].
• 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 [187].

• A detailed discussion of the "Moscow Embassy study" [70] 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 [168].
  • A review of the history of RF radiation safety guidelines [169].
  • A review of possible health risks from mobile phones from the World Health Organization [165].
  • A review of possible health risks from mobile phones from the American Cancer Society [163].
  • A review of international RF radiation safety guidelines and why they differ [164].
  • The Royal Society of Canada report was published in a biomedical journal along with an update [99].
  • IEEE COMAR Technical Information Statement on base stations [27].
  • IEEE COMAR Technical Information Statement on hand-held mobile phones [26].
• New epidemiology studies and experimental human studies:
  • Mobile phone RF radiation had no effect on melatonin levels or immune function in humans [166].
  • Exposure to RF radiation from GSM phones had no detectable subjective effects on human volunteers [160].
  • Headaches and other symptoms were reported to be higher in users of analog phones than users of digital phones [162].
  • A retrospective cohort study [155] 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 [113] reported that mobile phone RF caused sleep disturbance in human volunteers, when the study was repeated with a higher exposure intensity, the effect vanished [159].
  • A report [154] 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 [146] 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 [177]. See Q23B.
  • Exposure of mice to RF radiation did not promote chemically-induced skin cancer [175]. 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 [173].
  • RF radiation was not mutagenic in bacteria (the Ames test) [176]. See Q23C.
  • RF radiation did not cause chromosome damage in rats [174]. See Q23C.
  • Exposure of mice to digital or analog mobile phone RF radiation did not promote cancer (particularly lymphoma) induced by ionizing radiation [172]. See Q23A and Q23B.
  • Mobile phone RF radiation did not cause chromosome damage in human blood cells [167].
  • RF radiation at 4 W/kg had no effect on the blood-brain barrier of mice [170].
  • A study of RF radiation effects on "stress" responses in animals [161] found that restraint of animals for the exposure produced effects, but the RF radiation exposure itself did not.
  • Zook and Simmens [104] 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 [156].
  • No evidence for genotoxic or epigenetic activity in human lymphocytes exposed to 600 MHz GSM at 0.4-10 W/kg for 4 hrs [157].
  • RF exposure of pregnant rats had no affect in their offspring [145].
  • RF radiation may induce heat shock in worms without a detectable rise in temperature [148].
  • RF radiation did not damage chromosomes and did not enhance the activity of known carcinogens [149].
  • RF radiation did not cause cell transformation [151].
  • RF radiation did not cause chromosome damage and did not enhance micronucleus formation [150].
• 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 [171].
  • An analysis [147] 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 [158].

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.

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 [83]. 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 [1]
• the 1999 and 2000 reviews by Moulder and colleagues [95, 131]
• the 2000-2001 review by the Royal Society of Canada [99]
• the 2000 report of the UK Independent Expert Group on Mobile Phones (the "Stewart Commission") [128]
• the 2001 IEEE position paper [26]
• the 2001 review from the World Health Organization [165]
• the 2001 the review from American Cancer Society [163]
• the 2001 report from the US GAO [168]
• the new (in 2002) US FCC/FDA website [189]
• the 2002 report from the Health Council of the Netherlands [185]

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.) [23]. However, once the energy is absorbed the effects are the same.

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).

Yes. Mobile (cellular) phones and their base station antennas are two-way radios, and produce radiofrequency (RF) radiation [3]; that's how they work. This radiofrequency radiation is "non-ionizing", and its biological effects are fundamentally different from the "ionizing" radiation produced by x-ray machines [see Q6].

No. The interaction of biological material with an electromagnetic source depends on the frequency of the source [4]. X-rays, 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) [4].

The Electromagnetic Spectrum

No. Power lines produce no significant non-ionizing radiation, they produce electric and magnetic fields. In contrast to non-ionizing radiation, these fields do not radiate energy into space, and they cease to exist when power is turned off. It is not clear how, or even whether, power line fields produce biological effects; but if they do, it is not in the same way that high power 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.

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) [6], and the National Council on Radiation Protection and Measurements (NCRP) [7].

These radiofrequency standards are expressed in "plane wave power density", which is measured in mW/cm-sq (milliwatts per square centimeter) [8, 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 [9]. The ICNIRP standards are slightly lower and the NCRP standards are essentially identical [10].

In 1996 the U.S. Federal Communications Commission (FCC) released radiofrequency guidelines for the frequencies and devices they regulate, including mobile phone base station antennas [11]. The FCC standards for mobile phone base station antennas are essentially identical to the ANSI/IEEE standard [5].

The public exposure standards apply to power densities averaged over relatively short periods to time, 30 minutes in the case of the ANSI/IEEE, NCRP, and FCC standards (at mobile phone frequencies). Where there are multiple antennas, these standards apply to the total power produced by all antennas [13].

See international note 12 and Erdreich and Klauenberg [164].

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]:

1. The research on RF radiation is extensive [15], and is adequate for establishing safety guidelines.
2. 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 [126] for a discussion of the known effects of overexpose to RF radiation in humans.
3. Biological effects of RF radiation depend on the rate of energy absorption [8]; and within a broad range of frequencies (1 to 10,000 MHz), the frequency matters very little.
4. Biological effects of RF radiation are proportional to the rate of energy absorption; and the duration of exposure matters very little [96].
5. 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) [16].

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 [5] and the FCC [11].

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 [8].

The result was a highly conservative public exposure guideline that was set at a level that is only 2% of the level where replicated biological effects have actually been observed.

No. There are differences between the standards. ANSI/IEEE, ICNIRP, NCRP and FCC all use the same biomedical data, and the same general approach to setting safety guidelines. However, there are differences in the models used by the different groups, and hence there are slight differences in the final numbers [17, 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 [5] and ICNIRP [6], they do differ. See note 12 and Erdreich and Klauenberg [164] for details.

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 [11] that was based on a combination of the 1992 ANSI standard [5, 169] and the 1986 NCRP guidelines [7].

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 [135], the FCC guideline itself [11], and Foster and Moulder [131].

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 [77] 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 [123] measured RF levels in five schools, three of which had base stations on them or near them. All schools met Canadian, US and international RF standards by a wide margin. The maximum readings are shown in the following table.

In 2000, the U.K. National Radiation Protection Board [130] measured radiofrequency radiation levels at 118 publicly-accessible sites around 17 cell phone base stations. The maximum exposure at any location was 0.00083 mW/cm-sq (on a playing field 60 meters from a school building with an antenna on its roof). Typical power densities were less than 0.0001 mW/cm-sq (less than 0.01% of the ICNIRP public exposure guidelines). Power densities indoors were substantially less than power densities outdoors. When radiofrequency radiation from all sources (cell phone, FM radio, TV, etc.) was taken into account the maximum power density at any site was less than 0.2% of the ICNIRP public exposure guidelines. Details are shown in the following figure.

Radiofrequency Radiation Levels Near Mobile Phone Base Stations in the UK

The relationship between the RF power density and distance from the base of the tower or building on which the mobile phone base antenna was located. Adapted from Mann et al. [130].

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 [6] for public areas; the maximum in most schools was less than 0.1% 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.

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. Adapted from . http://www.radio.gov.uk/topics/mpsafety/school-audit/audit.htm/.

The relationship between the RF levels required to produce known biological effects, the RF levels specified in the FCC safety guidelines, and the RF levels found around mobile phone base stations is shown in the following figure.

Standards for Mobile Phone Base Stations

The relationship between the RF power density level required to produce known biological effects, the RF power density levels specified in the FCC safety guidelines, and the RF power density levels found around mobile phone base stations. Because the RF power density required to produce biological effects is dependent on frequency, this figure only applies to frequencies between 800 and 2200 MHz (that is, those currently used by analog and digital cellular phones).

Yes. There are some circumstances under which an improperly designed (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 [18]. This could arise for antennas mounted on or near the roofs of buildings. Petersen et al [77], 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 [9] 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.

While specific recommendations require a detailed knowledge of the site, the antenna, and the mounting structure, some general criteria can be described.

1. Antenna sites should be designed so that the public cannot access areas that exceed the 1992 ANSI [5] or FCC [11] 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 [18].
2. If there are areas accessible to workers that exceed the 1992 ANSI [5] or FCC [11] 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 [18].
3. If there are areas that exceed the 1992 ANSI [5] or FCC [11] 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 [18].

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 [11] require detailed calculations and/or measurement of radiofrequency radiation for some high-power rooftop transmitters, and some high-power transmitters whose antennas are mounted on low towers [19].

In general, the above guidelines will always be met when antennas are placed on their own towers. Problems, when they exist, are generally confined to:

• 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).

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,

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 [134].

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.

In general this will not be a problem.

1. As can be seen from the antenna patterns shown in Q14D, neither high- or low-gain antennas radiate much energy straight down.
2. 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).
3. FCC will require RF evaluations of all but the most low-powered roof-top transmitters (see note 19).
4. Even a worst-case calculation predicts that power density on the floor below an antenna will meet all current RF safety guidelines [55].
5. Actual measurements in top floor apartments and corridors confirm the power density will be far below all current RF safety guidelines [55].

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 [189] 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 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:

1. As discussed in Q12 and documented in the 2000 NRPB report [130], 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.
2. 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).
3. 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:

1. Increase the exposure of the users from their handsets.
2. Require the base antenna power to be increased.
3. Require the base antennas to placed further above the ground.
4. Increase the cell size and limit the number of users.

A detailed discussion of radio-frequency radiation occupational safety guidelines is beyond the scope of this FAQ.

In a detailed discussion of guidelines for telecommunications antenna installation, Tell [116] makes the following recommendations:

Specific Antenna Installation Guidelines (from Tell [116])

1. For roof-mounted antennas, elevate the transmitting antennas above the height of people who may have to be on the roof.
2. 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).
3. For roof-mounted directional antennas, place the antennas near the periphery and point them away from the building.
4. Consider the trade off between large aperture antennas (lower maximum RF) and small aperture antennas (lower visual impact).
5. Remember that RF standards are stricter for lower-frequency antennas (e.g., 900 Mhz) than for higher-frequency antennas (e.g., 1800 MHz).
6. Take special precautions to keep higher-power antennas away from accessible areas.
7. Keep antennas at a site as far apart as possible; although this may run contrary to local zoning requirements.
8. 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 [116])

1. 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.
2. "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]
3. Radio-frequency radiation levels at a site should modeled before the site is built.
4. Radio-frequency radiation levels at a site should measured.
5. Assume that all antennas are active at all times.
6. Disable (lock out) all attached transmitters before working on an antenna.
7. Use personal monitors to ensure that all transmitters have actually been shut down.
8. 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." [116]
9. "Keep on moving" and "avoid unnecessary and prolonged exposure in close proximity to antennas".
10. 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.
11. 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 [147] for an analysis of actual exposure levels to a person on a roof near a base station antenna.

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 [130]).

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 [130] and NCRP Report No. 119 [134].

Not everyone. Even among scientists there are a few people who claim that there is evidence that low level exposure to RF is hazardous (see, for example, Q15B and Q15C). However, even these scientists generally do not argue that power densities as low as those found around properly-designed base station antenna sites are hazardous.

Yes. The EPA asked the FCC to adopt parts of the 1986 NCRP guidelines [7] rather than the entire 1992 ANSI guidelines [5]. This the FCC did [11], and EPA has formally endorsed the FCC safety 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."

Yes and no. That claim was made in 1996, but follow-up studies in Australia (see below) and in the UK (see Q15D) contradict this claim.

Hocking and colleagues [28] published an "ecological" epidemiology study that compares municipalities "near TV towers" to those further away. No RF 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 [62] repeated the Hocking study [28]. McKenzie and colleagues looked at the same area, and at the same time period; but they made more precise estimates of the 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 [28] was an artifact.

Yes. In a 1995 article labeled an "opinion piece", Goldsmith [29A] argues that there is evidence that RF exposure is associated with mutations, birth defect, and cancer. This review is based largely on what the author admits to be "non-peer-reviewed sources", most of which are stated to be "incomplete" and to lack "reliable dose estimates". The author further states that "no systematic effort to include negative reports is made; thus this review has a positive reporting bias".

In an article based on a 1996 meeting presentation [29B] Goldsmith argues that epidemiological studies "suggest that RF exposures are potentially carcinogenic and have other health effects". His conclusions are based largely on:

• studies of RF exposure at the US embassy in Moscow (see Q15H and Hill [68]);
• the "geographical correlation" studies of Hocking et al [28] and Dolk et al [34, 35] that are discussed in Q15B and Q15D;
• the study of Korean war radar operators by Robinette et al [67] that is discussed in Q16.

Few scientists agree with the opinions expressed by Goldsmith (see, for examples the reviews of the RF epidemiology in 1, 5, 6, 7, 14, 53, 94, 139); and even fewer would be willing to base a conclusion on the types of data sources that Goldsmith relies on.

Yes and no. Dolk and colleagues [34] investigated a reported leukemia and lymphoma cluster near a high-power FM/TV broadcast antenna at Sutton Coldfield in the UK. They found that the incidence of adult leukemia and skin cancer was elevated within 2 km of the antenna, and that the incidence of these cancers decreased with distance. No associations at all were seen for brain cancer, male or female breast cancer, lymphoma or any other type of cancer.

Because of this finding, Dolk and colleagues [35] extended their study to 20 other high-power FM/TV broadcast antennas in the UK. Cancers examined were adult leukemia, skin melanoma and bladder cancer, and childhood leukemia and brain cancer. No elevations of cancer incidence were found near the antennas, and no declines in cancer incidence with distance were seen. This large study does not support the results found in the much smaller studies by the same authors at Sutton Coldfield [34] or by Hocking et al [28] in Australia.

Yes and no. Dr. Henry Lai (Department of Bioengineering, University of Washington, Seattle) has claimed at meetings that "low intensity" RF radiation has effects on the nervous system of rats. Dr. Lai has further claimed at meetings that there are published studies showing that RF radiation can produce "health effects" at "very low field" intensities.

Dr. Lai's own research has no obvious relevance to the safety of cell phone base stations since most of his studies were conducted with RF radiation intensities far above those that would be encountered near base stations. In general, Dr. Lai's studies were done with at a power density of 1 mW/cm-sq and an SAR of 0.6 W/kg [31, 92, 93]. This RF radiation intensity is over 100 times greater than that would be encountered in publicly-accessible areas near FCC-compliant base stations [16], and substantially exceeds the SAR limit that forms the basis of the FCC [11] and ANSI [5] safety guidelines for public exposure [17]. For further discussion of the research on possible effects of RF radiation on the nervous system see reviews by Lai [93] and Juutilainen and de Seze [90].

At a meeting in Vienna in 1998, and in a 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:

1. 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 [114].
2. 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 [76].
3. Decreased fertility in mice (Magras and Xenos, 1997) [86].
4. Decreased eating and drinking in mice (Ray and Behari, 1990) [88].
5. Changes in calcium transport in cells (Dutta et al, 1989) [89].
6. DNA damage (Phillips et al, 1998) [78].

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 [133] and Finnie et al [170] 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 [88] 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 [78] 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 [89] 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 [76] 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 [86] 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 [88] 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 [65] in Q23B) and see Stagg et al [161].
• 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 [89], the small decreases in cell growth reported by Kwee and Rasmark [76], nor the small changes in food consumption reported by Ray and Behari [88] 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.

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:

1. The study by Hardell et al [100] that is discussed in Q16.
2. The study by Preece et al [97] that is discussed in Q19C.
3. A new and then unpublished genotoxicity study.
4. 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 [138,188]. The published version reports no significant association between malignant [138] or benign [188] 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 [182]. The published version [182] 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 [150] and Bisht et al [191] 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.

United Kingdon

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 [128]. The full text is available at: http://www.iegmp.org.uk/IEGMPtxt.htm.

On the general issue of radio-frequency radiation safety, the U.K. Independent Expert Group concluded that:

"The balance of evidence to date suggests that exposures to RF radiation below NRPB [14] and ICNIRP [6] guidelines do not cause adverse health effects to the general population... 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 [97] and Koivisto et al [117] 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 [97] and Koivisto et al [117] and on the European Union "Precautionary Principle" [129]. 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 [129].

Canada

An Expert Panel assembled by the Royal Society of Canada issued a report on mobile phone safety in 1999 [99]. 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."

United States

In 2001 the Institute of Electrical and Electronics Engineers (IEEE) published a statement on mobile phone base stations [27]. The report is on-line at: http://www.seas.upenn.edu:8080/~kfoster/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 states 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..."

In 2002, the Health Council of the Netherlands issued a report on the safety of mobile phones [185]. The report is on-line at: http://www.gr.nl/OVERIG/PDF/02@01E.PDF. 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 [186] 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) [179]. 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 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."

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 [70] 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 [70] 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"

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 [94] and Rothman [139].

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 [94] 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 [94] 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 [67], Hill [68], Milham [69], Morgan et al [118] and Groves et al [187]. 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 [118] studied all major causes of mortality (with emphasis on brain cancer, lymphoma and leukemia) in employees of Motorola, a manufacturer of wireless communication products. Based on job titles, workers were classified into high, moderate, low, and background RF exposure groups. For workers with moderate or high 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 [187] 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 [67].

The other studies of acceptable design (Lilienfeld et al [70], Lagorio et al [71], Muhm [72], Tynes et al [73], Grayson [33], and Thomas et al [105]) 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 [79] 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 [94] 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. [121] published a study that reviewed health records of more than 250,000 mobile phone users. They found no difference in mortality between the users of hand-held portable phones (where the antenna is placed close to the head) and car-mounted mobile phones (where the antenna is mounted on the vehicle). In a 1999 follow-up study [122], the same group examined specific causes of death among nearly 300,000 mobile phone users in several U.S. cities. The investigators found no difference in overall cancer rates, leukemia rates, or brain cancer rates between the users of hand-held portable phones and the users of 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 [100], the second by Muscat et al [138], the third by Inskip et al [143], and the fourth by Johansen et al [155]. 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 [100] reported a non-significant excess of temporal lobe tumors, but Muscat et al [138], Inskip et al [143] and Johansen et al [155] reported a non-significant decrease of these tumors. Hardell et al [100] 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 [138] and Inskip et al [143] reported non-significant trends in the opposite direction (see details below).

In the first of the mobile phone case-control studies, Hardell et al. [100] 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 [100], Muscat et al [138], Inskip et al [143], and Johansen et al [155]. 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 [138] 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 [138] 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. [100] did not explicitly analyze this histopathological subtype of tumor, but Inskip et al [143] found a decreased incidence of neuroepitheliomas.

As soon as Muscat et al [138] was published, NEJM rushed a similar study onto their website that had been scheduled for publication in January of 2001. Inskip et al [143] 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 [143] 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 [155] 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 [152] 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 [155] found less melanoma and ocular cancer than expected in cell phone users. According to the accompanying editorial [153]:

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 [188] 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 [138] 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 [94] concluded that:

Several positive associations suggesting an increased risk of some types of cancer in those who may have had greater exposure to RF emissions have been reported. However, the results are inconsistent: there is no type of cancer that has been consistently associated with RF exposures. The epidemiologic evidence falls short of the strength and consistency of evidence that is required to come to a reasonable conclusion that RF emissions are a likely cause of one or more types of human cancer. The evidence is weak in regard to its inconsistency, the design of the studies, the lack of detail on actual exposures, and the limitations of the studies in their ability to deal with other likely relevant factors. In some studies there may be biases in the data used

In a 2000 review of the RF epidemiology literature, Rothman [139] 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.

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 [140]. 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 [90] who concluded that:

The literature relevant to the possible biological effects of AM radiofrequency radiation consists of scattered observations using a wide variety of experimental models and exposure parameters... Several studies have reported findings consistent with effects on the nervous system and cancer-related biological processes. However, the methods and exposure parameters vary widely, and no independent replications of the positive finds have been reported. The results available today fail to support the existence of well-defined modulation-specific bioeffects from exposure to radiofrequency radiation.

For recent reports of attempts to find differences between the biological effects of continuous-wave and modulated RF radiation, see Pakhomov et al [178] (who reported no difference) and 'D'Ambrosino et al [180] (who reported a difference).

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

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.

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].

It is possible that use of cell phones causes headaches.

In 1998, Frey [48] reported anecdotal evidence that cell phones cause headaches.

In 2000, Oftedal et al [154] 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 [162] 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 [142] 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.

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 [82] reported that human volunteers using a GSM cell phone for 35 minutes showed a 5-10 mm Hg rise in blood pressure. The study is small and was not blinded, and a rise in blood pressure of this magnitude has no known health consequences.

- Eulitz et al [84] reported that cell phones can alter the electrical activity of the brain. However, the effect may be an artifact caused by RF interference with the EEG leads.

- Freude et al [111] exposed human volunteers to RF from a 916 Mhz 350 mW GSM digital phone. Small changes in EEG were seen that "did not indicate any influence on human performance, well-being and health"

- In 1996 Mann and Röschke [113] 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 [115], and no effect at all when the power density was increased to 5 mW/cm-sq [159].

- 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 [108] reported that exposure of human volunteers to cell phone RF had no effect on night-time secretion of melatonin. In 2001, Radon et al [166] 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 [109] reported that rats exposed to 2450 MHz pulsed radio-frequency radiation showed "defects in long-term memory". The RF-exposed animals were slower than normal animals to learn a maze. Animals received whole-body RF exposure for 1 hr/day. The average SAR was 1.2 W/kg with peaks of 3-4 W/kg. The signal is quite different from that associated with a mobile phone base station and the peak SAR may have been high enough to cause thermal stress. The exposure intensity (SAR) was 15 times higher than the FCC standard for whole-body exposure of the general public. In 2000 Sienkiewicz et al [120] performed a similar experiment in mice (but using a signal and a power-density simulating a European digital cell phone base station signal) and found no effects on maze performance.

- In 1999, Preece et al [97] reported that exposure of human volunteers to cell phone RF radiation might decrease reaction times. 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 [97] found an effect for