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HUMAN EXPOSURE TO RADIO-FREQUENCY
FIELDS FROM POLICE RADARS
As Approved by the IEEE United States Activities Board
May 1992
*************************************
We recognize public concern about the safety of exposure to
electromagnetic fields. Recent allegations in the media link
cancer with exposure to police radars, one of the lowest power
microwave systems in our modern society -- typically between 10 and
100 milliwatts.
Guidelines for safe limits of exposure to microwaves have been
published by the Institute of Electrical and Electronics Engineers
(IEEE C95.1, 1991) and the American National Standards Institute
(ANSI C95.1, 1982). These guidelines were developed to protect
human beings from harmful exposure to radio frequency
electromagnetic fields. Our Committee on Man and Radiation (COMAR)
has stated that prolonged exposure at or below the levels
recommended in ANSI C95.1-1982 is not hazardous to human health
based on present knowledge (IEEE-USA COMAR, 1990).
Measurements and analysis of microwave exposures near properly
operating police radar units have shown that even maximal exposure
levels are well below these recommended safety limits. In
addition, human exposures near police radar are substantially below
the limits set by other national and international standards.
Therefore, it can be concluded that microwave exposures near police
radar are safe by existing standards and that there is no
scientific basis for the alleged link of police radar with cancer.
This statement was developed by the Committee of Man and Radiation
of the United States Activities Board of The Institute of
Electrical and Electronics Engineers, Inc. (IEEE), and represents
the considered judgment of a group of U.S. IEEE members with
expertise in the subject field. The IEEE United States Activities
Board promotes the career and technology policy interests of the
250,000 electrical, electronics, and computer engineers who are
U.S. members of the IEEE.
BACKGROUND
Police radar was first introduced in the late 1940s as an offshoot
of World War II radar technology. From time to time, there has
been controversy over the accuracy of police radar in speed limit
enforcement. Nevertheless, police radar has evolved into an
accepted means of traffic control, with more than 75,000 radar
units in use in the United States.
The microwave properties of speed radars have been known for years.
In 1981, tests on 22 radar units showed that power densities were
less than 3 mW/cm2 at the aperture and that exposure decreased with
separation from the radiating horn (Baird, 1981). Police radar
operates at X and K-band frequencies (i.e., 10-35 GHz), with a
continuous-wave signal (no modulation), and with output power in
the range of 10 to 100 milliwatts. The vast majority of police
radars operate between 10-25 milliwatts, although a small number of
100 milliwatt devices are still in service. By comparison, the
power output of a child's walkie- talkie is 35 milliwatts, and
cellular hand-held radio-telephones operate at power levels of
hundreds of milliwatts. In today's society, many products utilize
similar technology and similar frequencies: alarm systems,
automatic door openers, motion detectors, and various personal
communications networks and inter-computer network systems.
Thousands of products produce environmental radio-frequency fields
at similar or higher intensities and in a broad range of
frequencies (e.g., microwave ovens, mobile radios, electronic news
gathering systems, broadcasting, amateur radio, and other devices).
Police radar is a low-power system when compared against today's
inventory of existing radio-frequency systems. The total power,
even if concentrated at a point as in a coaxial connector, is
insufficient to produce pain or skin burn (Osepchuk, 1983).
Microwaves at police radar frequencies are absorbed almost wholly
in the skin, and the power densities near a police radar are well
below the threshold for thermal sensation at X-band (Hendler,
1968).
Biological research with animals at these frequencies has shown
biological effects only at much higher powers (Rosenthal, et al,
1976 and Hagan, et al, 1976). At least 1 watt of power is
necessary to produce a cataract in irradiated rabbits at X-band.
At 35 GHz, no cataracts result for less than 600 milliwatt contact
application to the rabbit eye. Minimal corneal damage under
contact conditions occurs only for at least 50 milliwatts delivered
continuously for 0.5 hours to a small area in the eye.
Concerns about health effects (e.g., alleged cataracts) from police
radar apparently first surfaced in 1987 in a letter distributed by
Silicron Technologies (Tunnell, 1987). This claim received no
scientific support and in time disappeared. In 1990, a police
officer from Ohio, Gary Poynter, published a report (Poynter, 1990)
that alleged a link between police radar exposure and cancer. As
a prime example of biological effects of microwave energy at X-
band, Poynter selected the series of experiments on Tenebrio
molitor reviewed by Heynick and Polson (1983). They, however, did
not interpret these experiments as contradictions to ANSI C95.1-
1982. Furthermore, some of the early work on Tenebrio molitor
suggested effects of low power levels, which later were found not
to exist (Olsen, 1981). The allegations of Poynter have been
expanded in a series of media events -- particularly a series of
articles in Law Enforcement News (1990-1991).
Recently, Fisher (1991) measured police radar units and confirmed
the results of Baird (1981). Fisher concluded that maximum
exposure during normal use of a hand-held radar device is less than
0.05 mW/cm2. The newer radars tend to be at lower power than older
ones included in the 1981 tests. As a low power device, police
radar is exempt from the requirement of providing evidence of
compliance with ANSI C95.1-1982. This exemption was recently
confirmed to our Committee on Man and Radiation by the Federal
Communications Commission (Cleveland, 1991). Police radar has been
examined by the Food and Drug Administration (FDA), and no action
by the FDA relative to its responsibilities under the Electronic
Product Radiation Control for Health and Safety Act of 1968 was
deemed warranted (Anderson, 1991). THE FDA STATED THAT IT KNOWS OF
"NO CONVINCING EVIDENCE OF A RISK OF CANCER OR OTHER HAZARDS FROM
EXPOSURE TO THE LEVEL AND TYPE OF MICROWAVE RADIATION PRODUCED BY
POLICE RADAR UNITS." As an extra precaution to "ensure that no
violations of existing standards can occur," the FDA recently
suggested that the radar antenna be kept at least six inches from
the body while transmitting. The FDA also stated that "emissions
from police radar units contain no ELF modulation and have not been
associated with the present ELF-cancer controversy."
There is no scientific basis for worry that exposure to police
radar may cause or promote cancer. Underlying our position is its
reliance on the validity of existing science-based safety
standards. Exposure to police radar satisfies the limits of not
only IEEE and ANSI standards but also other standards both in the
U.S. (NCRP, 1986) and elsewhere in the world (IRPA, 1988). We
believe that continuing research on biological effects is necessary
across the whole electromagnetic spectrum, in order to ensure an
up-to-date refinement and improvement of existing safety standards.
REFERENCES
1. Andersen, F. (1991), Letter to COMAR dated June 20, 1991.
DCRH, FDA, Rockville, MD.
2. ANSI C95.1 (1982), American National Standard: Safety
Levels with Respect to Human Exposure Radio Frequency
Electromagnetic Fields, 300 kHz to 100 GHz, IEEE
Standards Dept., Piscataway, NJ.
3. Baird (1981), Field Strength Measurements of Speed
Measuring Radar Units, NBSIR 81-2215, NBS, Washington,
DC.
4. Cleveland, R. (1991), Letter to COMAR dated May 13, 1991.
FCC Office of Engineering and Technology, Washington, DC.
5. Fisher, P.D. (1991), Microwave Exposure Levels
Encountered by Police Traffic Radar Operators, Technical
Report MSU-ENGR-91-007, Michigan State University, East
Lansing, MI.
6. Hagan, et al, (1976) in Biological Effects of
Electromagnetic Waves, C.C. Johnson and M.L. Shore,
editors, Department of Health, Education and Welfare, pp.
143-153.
7. Hendler, E. (1968), "Cutaneous Response to Microwave
Irradiation" in Thermal Problems in Aerospace Medicine,
J.D. Hardy, editor. Surrey, Unwins Ltd.
8. Heynick, L. and Polson, P. (1983), "Bioeffects of Radio
Frequency Radiation: A Review," USAF School of Aerospace
Medicine, Brooks AFB, TX.
9. IEEE C95.1 (1991), Safety Levels with Respect to Human
Exposure to Radio Frequency Electromagnetic Fields, 3 kHz
to 300 GHz, IEEE Standards Dept., Piscataway, NJ.
10. IEEE-USA Entity Position Statement (1990) "Human Exposure
to Microwaves and Other Radio Frequency Electromagnetic
Fields," IEEE-USA COMAR, Washington, DC.
11. IRPA (1988), "Guidelines on Limits of Exposure to Radio
Frequency Electromagnetic Fields in the Frequency Range
from 100 kHz to 300 GHz," Health Physics, Vol. 54 (1) pp.
115-123.
12. Law Enforcement News, (1990-1991), a series of articles
beginning Nov. 15, 1990 to March 15, 1991 on "Police
Radar and Health Problem Allegations."
13. NCRP (1986), Biological Effects and Exposure Criteria for
Radio Frequency Electromagnetic Fields, Report No. 86.
National Council on Radiation Protection and Measurement,
Bethesda, MD.
14. Olsen R. (1981), Microwave Induced Developmental Effects
in the Common Mealworm (Tenebrio Molitor) - A Decade of
Research, NAMRL Report No. 1283, U.S. Navy, Pensacola,
FL.
15. Osepchuk, J.M. (1983), "The Microwave Stimulus," in
Microwaves and Thermoregulation, E.R. Adair, Editor,
Academic Press, NY, pp. 33-56.
16. Poynter, G. (1990), Traffic Radar: Human Experimentation
Without Informed Consent available for $40.00 from
Priority-One Consultants, 4535 West Sahara Ave., Suite
105-126M, Las Vegas, NV 89102.
17. Rosenthal, et al (1976) in Biological Effects of
Electromagnetic Waves, C.C. Johnson and M.L. Shore,
editors, Department of Health, Education, and Welfare,
pp.110-125.
18. Tunnell, J., (1987) Letter on Police Radar from Silicron
Technologies dated Jan. 7, 1987. |
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