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Summary
Occupational and industrial radiation protection programs are
concerned with the exposure of individuals to a radiation environment
during their occupations. There are approximately 3.7 radiation workers
per 1,000 people in the United States, and in 1970 the average annual
individual occupational dose was 0.8 mrem/y.
The data indicate that the largest occupational exposures generally
are received by waste disposal workers and, to a lesser extent, by
industrial radiographers.
The highest occupational personnel exposures from U.S. operating
nuclear power plants for the period 1969-1975 have resulted from inplant
maintenance activities.
The yearly average person-rem per reactor year at pressurized water
reactors was 309 for 1975, a decrease from the previous year; for boiling
water reactors, the yearly average person-rem per reactor year had in-
creased in 1975 to 670 from 507 in 1974.
Table 9-23. Plutonium systemic body burden estimates
for selected Manhattan project plutonium workers at
three different times9 (9.19)
i (nCi)
CASE CODE
1953
30-60
80
80
80
60
60
40
1962
10
130
140
140
70
80
90
1972
210
420
260
180
140
150
130
1
3
4
5
6
7
17
aPERSONS WITH MORE THAN 120 nCi 239-240Pu SYSTEMIC
BURDEN IN 1972.
255
-------
References
(9.1) KLEMENT, A. W., C. R. MILLER, R. P. MINX, and B. SHLEIEN.
Estimates of ionizing radiation doses in the United States,
1960-2000. EPA, Office of Radiation Programs, Division of
Criteria and Standards, Washington, D.C. 20460 (August 1972).
(9.2) UNITED NATIONS SCIENTIFIC COMMITTEE ON THE EFFECTS OF ATOMIC
RADIATION. Report to the General Assembly. Ionizing Radiation:
Levels and Effects. Volume 1:Levels. United Nations, New York
(1972).
(9.3) FEDERAL RADIATION COUNCIL. Radiation protection guidance for
federal agencies. Federal Register (May 18, I960).
(9.4) ADVISORY COMMITTEE ON THE BIOLOGICAL EFFECTS OF IONIZING RADI-
ATION. The effects on populations of exposures to low levels of
ionizing radiation. Division of Medical Sciences, National
Academy of Sciences, National Academy of Sciences, National
Research Council, Washington, D.C. 20006 (November 1972).
(9.5) ATHERTON, N. S. An investigation of the radiation doses
received by industrial radiographers. British Journal of
Non-destructive Testing (July 1973).
(9.6) HOLADAY, D. A. Evaluation and control of radon daughter
hazards in uranium mines, NIOSH 75-117. Department of
Health, Education, and Welfare, Public Health Service,
Center for Disease Control, National Institute for Occupa-
tional Safety and Health, Rockville, Md. 20852 (November 1974).
(9.7) ARGONNE NATIONAL LABORATORY. Radiological and Environmental
Research Division Annual Report, ANL-76-88, Part II. Center
for Human Radiobiology, Argonne National Laboratory, 9700
South Cass Avenue, Argonne, Illinois 60439 (1976).
(9.8) ARGONNE NATIONAL LABORATORY. Fact Sheet on Studies of the
Health of Former Thorium Workers. Center for Human Radio-
biology, Argonne National Laboratory, Argonne, Illinois
60439 (November 1, 1976).
(9.9) ARGONNE NATIONAL LABORATORY. Fact Sheet on Radium Project
Registry. Center for Human Radiobiology, Argonne National
Laboratory, Argonne, Illinois 60439 (November 1, 1976).
(9.20) MOGHISSI, A. A. and M. W. CARTER. Public health implications of
radioluminous materials, FDA 76-8001. DHEW, PHS, FDA, Bureau of
Radiological Health, Rockville, Md. 20852 (July 1975).
256
-------
(9.11) TSE, A. N. Measurement of radiation exposure received by
flight attendants from shipments of radioactive material,
NR-DES-0001. Division of Engineering Standards, Office
of Standards Development, Nuclear Regulatory Commission,
Washington, D.C. 20555 (November 1976).
(9.12) BROOKS, B. G. Eighth annual occupational radiation exposure
report 1975, NUREG-0119. Operating Data Branch, Operations
Evaluation Division, Office of Management Information and
Program Control, Nuclear Regulatory Commission, Washington,
D.C. 20555 (October 1976).
(9.13) FEDERAL REGISTER. Performance testing of personnel dosimetry.
Federal Register, Vol. 41, No. 198 (Tuesday, October 12, 1976).
(9.14) NUCLEAR REGULATORY COMMISSION. Discussion paper on performance
testing of personnel dosimetry. Office of Standards Develop-
ment, Nuclear Regulatory Commission, Washington, D.C. (1976).
(9.IS) MURPHY, T. D., N. J. DAYEM, J. S. BLAND, and W. J. PASCIAK.
Occupational radiation exposure at light-water-cooled power
reactors, 1969-1975, NUREG-0109. Radiological Assessment
Branch, Environmental Evaluation Branch, Nuclear Regulatory
Commission, Washington, D.C. 20555 (August 1976).
(9.16) ENERGY RESEARCH AND DEVELOPMENT ADMINISTRATION. Eighth annual
report of radiation exposures for ERDA and ERDA contractor
employees, 1975, ERDA 77-22. Division of Safety, Standards,
and Compliance, Energy Research and Development Administration,
Washington, D.C. (1977).
(9.17) BREITENSTEIN, B. D., JR., M.D., W. D. NORWOOD, M.D., and C. E.
NEWTON, JR. United States Transuranium Registry Annual Report,
Act 1, 1975 to October 1, 1976, HEHF-24. Hanford Environmental
Health Foundation, Richland, Washington 99352 (December 1976).
(9.18) HEMPELMANN, L. H., W. H. LANGHAM and others. Manhattan project
plutonium workers: a twenty-seven year follow-up study of
selected cases. Health Physics, Vol. 25, pp. 461-479 (Novem-
ber 1973).
(9.19) ENVIRONMENTAL PROTECTION AGENCY. Proceedings of public hearing:
plutonium and the other transuranium elements, Vol. 1,
December 10-11, 1974. Criteria and Standards Division, Office
of Radiation Programs, Environmental Protection Agency,
Washington, D.C. 20460.
257
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Chapter 10 - Radioactivity in Consumer Products
Smoke detectors for homes and digital wristwatches are recent
arrivals on the market of consumer products containing radioactive
materials, whereas, artificial teeth and dinnerware containing these
materials have been in use for some time. However, information has
recently become available as to the amount of radiation exposure these
products contribute to the members of the general population.
In addition to the consumer products containing or producing radi-
ation discussed in this report, it is recommended that the reader refer
to the previous Radiological Quality of the Environment report for
additional sources of radiation exposure (10.1). Sources discussed in
the last report included television sets and timepieces containing
radioactive material.
Radioactivity in digital wristwatohes
Electronic digital watches are a viable consumer product offering
many advantages over the traditional mechanical timepieces. The two
technologies used in the digital electronic watch market are LED's (for
light emitting diodes) which give a readout on demand and LCD's (for
liquid crystal display) which give a continuous readout.
The LCD is a passive display meaning that it does not emit light
but instead attenuates existing light. This is accomplished by util-
izing a thin film of specifically oriented liquid crystal material whose
interaction with polarized light and an electric field is the basis for
the display operation. The advantage of the LCD is that it requires
very little power to operate but its usefulness is limited by its lack
of visibility under low level lighting conditions.
In February of 1976, the first LCD watch utilizing sealed tritium
luminous sources appeared on the market. This display results in a
truly legible display under all lighting conditions. It consist of a
hollow glass tube whose inside walls are coated with an inorganic
phosphor and then evacuated and back filled with tritium gas and laser-
sealed. The radioactive decay of the tritium gas releases a low energy
beta which in turn transfers its energy to the phosphor which then
releases this excess energy in the form of light. These tubes, placed
behind a liquid crystal display, result in a self-contained lighting
system completely independent of external power. The total tritium
content of these tubes is 200 mCi or less per watch (10.2).
259
-------
Although the tubes have a diffusion rate of less than 0.1 yCi/24
hours, tests have shown that in general the watches exhibit a diffusion
rate of less than 0.01 nCi/24 hours which is equal to less than 0.5 mrem
per year. However, the watches are constructed to make tube breakage
unlikely and to prevent the curious consumer from reaching the tubes
themselves.
Radioactive materials in ceramio glazes
Uranium has been used as a coloring agent in glazes and glass since
the 18th century. In the 19th century, these materials were discovered
to be radioactive as a result of their fogging of photographic film.
However, various combinations of uranium salts and oxides were utilized
to render a variety of colors and fluorescences to a wide variety of
glassware early in the 20th century.
In 1961, the Atomic Energy Commission permitted the use of "exempt"
quantities of uranium not to exceed 20 percent in the glaze of ceramic
tableware and no more than 10 percent in glassware. The AEC did not
consider these levels of uranium to be a significant radiation hazard.
In 1971, the Bureau of Food in the Food and Drug Administration
(FDA) conducted radiation measurements and 24-60 hour "soak" experiments
using 4 percent acetic acid solutions to duplicate storage of certain
"acid foods" such as sauerkraut, etc. They found a concentration of 55
ppm uranium and 66 ppm lead in the 60-hour leach solution.
The Bureau of Radiological Health, FDA concluded that the radiation
levels, although low, constituted an unnecessary and avoidable exposure
to the public. Based on the leach data, such dishware is also subject
to the food additives clause of the Food, Drug and Cosmetic Act and
subject to its regulations.
In 1974, the Nuclear Regulatory Commission used a "CONDOS" model
(10.3) and a computer code to estimate the population exposure to the
distribution, use and disposal of a variety of consumer products con-
taining radioactive material (20.4). Tableware that was assumed to
contain 20 percent natural uranium in the glaze was included in the
study. With all the parameters considered, dishwashers, waiters and
patrons were the only subjects receiving measurable doses. In terms of
whole body doses, dishwashers received 34.4 mrem/y, waiters 7.93 mrem/y
and patrons 0.18 mrem/y.
As a result of adverse publicity and the threat of regulatory
controls, manufacturers no longer use uranium as a color additive.
However, tableware containing uranium in its glaze is still available in
antique shops as collectors' items.
260
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Smoke detectors containing radioactive mater>-ial
Modern smoke detectors give early warnings of incipient fire condi-
tions and this is an effective means of reducing the loss of lives and
property from fires. The ionization chamber smoke detector uses radio-
active material to ionize the air in its sensing chamber, permitting the
flow of electrical current. Visible and invisible smoke particles
produced by initial thermal decomposition, upon entering the sensing
chamber, change the electrical characteristics of the ion flow, resulting
in the sounding of an alarm.
Although radium-226 was originally used and is still used by a few
small manufacturers, americium-241 is now the most widely used source
material for ionizing radiation in smoke detectors. 2U1Am, in the form
of americium oxide, is mixed with gold and contained in a thin metal
foil with silver and gold backing and cover. The foil, in the form of
small strips or discs, is fixed mechanically to source holders which are
then mounted in the smoke detectors.
Smoke detectors for use in commercial and industrial properties
typically contain 15 microcuries (yCi) of 2ttlAm. Whereas the single
units used in homes contain 1 pCi or less of 241Am or, in the few cases
where used, 0.1 pCi of radium-226 (10.5).
The U.S. population is expected to be 287,000,000 in the year 2000.
Assuming that 50 percent of the living units will have 2 ionization
chamber smoke detectors per unit and that there will be 2.75 persons per
unit, the calculated average individual dose rate will be 7.4 prad/y and
the calculated average population dose rate will be 1.4 yrad/y.
The Nuclear Regulatory Commission (NRC) estimates that a home ioni-
zation smoke detector held within 10 inches of the body for eight hours
a day, every day for a year, will expose a person to only 1/10 of the
radiation received in a roundtrip flight across the United States.
All U.S. manufacturers of smoke detectors containing 241Am operate
under license from the NRC and comply with its requirements and regu-
lations for manufacturing and distribution of their products. Thus, the
benefits to be gained from the use of ionization chamber smoke detectors
outweigh the risks that might be involved.
Uranium in dental porcelain
For over half a century, the manufacturers of artificial teeth have
added uranium salts to porcelain in an attempt to match coloring and
fluorescence of natural teeth under all lighting conditions. While the
resulting porcelain tooth matches the function, durability, and appearance
of the natural tooth, its accompanying risks are not known.
261
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The Bureau of Radiological Health (BRH) of the Food and Drug
Administration conducted a study on the radiation hazards of porcelain
in dental prostheses. The data from that study were published as a
technical report in September 1976 (10.6). Eighteen sets of artificial
teeth and 23 powders submitted by domestic and foreign manufacturers
were analyzed for alpha emissions, beta emissions, and uranium concen-
trations (Table 10-1).
'Uranium concentrations in the porcelain teeth ranged from less than
0.001 to 0.044 percent. According to NRC, sources containing less than
0.050 percent uranium do not require a license to possess or use. The
alpha dose rate for the set of teeth with highest uranium concentration
was calculated to be 137 mrem per year. However, this dose was based on
the assumption of intimate and continuous contact between teeth and oral
tissues. This assumption is not valid because saliva and other absorbers
are always present and many prostheses are not worn continuously. It
was also observed that alpha doses are absorbed entirely in the super-
ficial layer of the tissue and do not penetrate to the basal layer;
thus, the possibility of producing a malignancy is minimized.
The dose rate for the more penetrating beta particles was calcu-
lated by determining the fraction of the measured flux resulting from
uranium and the fraction resulting from potassium-40, which is a natur-
ally occurring component of porcelain. This resulted in a beta dose
rate ranging from 0.00 to 1.19 rem per year for uranium and from 0.08 to
0.2 rem/year for potassium-40 (table 10-2). Although these values may be
considered overestimates because of the assumption of continuous contact
between teeth and tissues, the dose reduction would not be as great as
with the alphas because of the deeper penetration of the high energy
beta particles.
Although the radiation dose from the amount of uranium presently
used in artificial teeth does not create a significant health hazard,
the dental industry has been urged by BRH to find a nonradioactive
substitute within a reasonable period. Until a practical substitute for
uranium becomes available, BRH has recommended a maxiumum permissible
concentration of uranium in dental porcelain of 0.037 percent. This
would reduce the probability that the dose from artificial teeth might
exceed the 1.5 rem per year limit set by the International Commission on
Radiation Protection.
References
(W.I)' OFFICE OF RADIATION PROGRAMS. Radiological quality of the
environment, EPA-520/1-76-010, K. L. Feldmann, editor, Office
of Radiation Programs, Washington, D.C. 20460 (May 1976).
RISTAGNO, C. V. The use of luminous sources for lighting
digital wrist watches. Symposium, Public Health Aspects of
Radioactivity in Consumer Products, Radisson Inn, Atlanta,
Georgia (February 2-4, 1977).
262
-------
Table 10-1. Uranium concentration in dental
porcelain (10.6)
Porcelain
Sample no.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
teeth
Percent uranium
0.030
0.037
0.017
0.019
0.037
0.001
0.044
<0.001
0.007
0.037
0.003
0.020
0.044
0.028
0.008
0.025
0.037
0.003
Sample
A
B
C
D
E
F
G
H
I
J
K
L
M
N
0
P
Q
R
S
T
U
V
w
Porcelain powders
no. Percent Uranium
0.040
(a)
0.019
0.099
0.013
0.023
0.006
0.003
0.017
0.027
0.025
0.053
0.027
0.002
0.035
0.019
0.028
0.007
0.038
(a)
(a)
0.022
0.017
JSample too small to yield significant count rate over background.
263
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Table 10-2. Annual dose from beta particle fluxes of
porcelain teeth (10.6)
Dose
(rem/y)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
238u
0.81
1.00
0.46
0.51
1.00
0.03
1.19
0.00
0.19
1.00
0.08
0.54
1.19
0.76
0.22
0.68
1.00
0.08
4°K
0.18
0.19
0.18
0.16
0.17
0.13
0.17
0.14
0.08
0.17
0.16
0.16
0.20
0.18
0.16
0.16
0.19
0.14
Total
0.99
1.19
0.64
0.67
1.17
0.16
1.36
0.14
0.27
1.17
0.24
0.70
1.39
0.94
0.38
0.84
1.19
0.22
264
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(10.3) O'DONNELL, F. R., L. R. MCKAY, 0. W. BURKE, and F. H. CLARK.
CONDOS - a model program, ORNL-TM-4663, Publication No. 638
Environmental Sciences Division, Oak Ridge National Laboratory,
Oak Ridge, Tenn.
(10.4) SIMPSON, R. E. A review of the use of radioactive material
in ceramic glazes. Symposium, Public Health Aspects of Radio-
activity in Consumer Products, Radisson Inn, Atlanta, Georgia
(February 2-4, 1977).
(10.5) JOHNSON, J. E. Smoke detectors containing radioactive materials,
Symposium, Public Health Aspects of Radioactivity in Consumer
Products, Radisson Inn, Atlanta, Georgia (February 2-4, 1977).
(10.6) THOMPSON, D. L. Uranium in dental procelain, (FDA) 76-8061,
Bureau of Radiological Health, Rockville, Md. 20857 (September
1976).
265
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Chapter 11 - Health Effects of Ionizing Radiation Exposure
Potential health effects from exposures to ionizing radiation are
evaluated in this section. In order to make the interpretation of these
estimated health effects more meaningful, the various health effect risk
factors that can be applied will be presented.
No attempt has been made to assign individual exposure values to
the various health effects for the following reasons. First, then, is a
degree of uncertainty for the doses from different radiation sources.
Although reported doses are based on actual data whenever possible, many
of the values represent estimates having a large degree of variability.
A second constraint on estimating potential health effects is the lack
of definitive information on population parameters, especially where
exposures are reported for specific facilities. This is important as
there are differences in sensitivity; for example, children are more
radiosensitive than adults. Therefore, while one might apply such risk-
conversion factors to large population groups where some generalizations
as to population parameters are applicable, it is invalid to apply such
generalizations when the population under consideration becomes smaller
and more specific. Besides these two prime reasons, others, such as the
lack of information on the pathway of exposure in many cases, have led
to the decision to handle health effects in this general manner.
EPA has adapted the policy of assuming a linear relationship
between the population exposure to ionizing radiation and its biological
effect. This policy was issued on March 3, 1975, and is included here
in its entirety.
"EPA Policy Statement on
Relationship Between Radiation Dose and Effect
41 FR 28409
"The actions taken by the Environmental Protection Agency to protect
public health and the environment require that the impacts of contam-
inants in the environment or released into the environment be prudently
267
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examined. When these contaminants are radioactive materials and ion-
izing radiation, the most important impacts are those ultimately af-
fecting human health. Therefore, the Agency believes that the public
interest is best served by the Agency providing its best scientific
estimates of such impacts in terms of potential ill health.
"To provide such estimates, it is necessary that judgments be made
which relate the presence of ionizing radiation or radioactive materials
in the environment, i.e., potential exposure, to the intake of radio-
active materials in the body, to the absorption of energy from the
ionizing radiation of different qualities, and finally to the potential
effects on human health. In many situations, the levels of ionizing
radiation or radioactive materials in the environment may be measured
directly, but the determination of resultant radiation doses to humans
and their susceptible tissues is generally derived from pathway and
metabolic models and calculations of energy absorbed. It is also
necessary to formulate the relationships between radiation dose and
effects; relationships derived primarily from human epidemiological
studies but also reflective of extensive research utilizing animals and
other biological systems.
"Although much is known about radiation dose-effect relationships
at high levels of dose, a great deal of uncertainty exists when high
level dose-effect relationships are extrapolated to lower levels of
dose, particularly when given at low dose rates. These uncertainties in
the relationships between dose received and effect produced are recog-
nized to relate, among many factors, to differences in quality and type
of radiation, total dose, dose distribution, dose rate, and radiosen-
sitivity, including repair mechanisms, sex, variations in age, organ,
and state of health. These factors involve complex mechanisms of inter-
action among biological, chemical, and physical systems, the study of
which is part of the continuing endeavor to acquire new scientific
knowledge.
"Because of these many uncertainties, it is necessary to rely upon
the considered judgments of experts on the biological effects of ion-
izing radiation. These findings are well-documented in publications by
the United Nations Scientific Committee on the Effects of Atomic Radi-
ation (UNSCEAR), the National Academy of Sciences (NAS), the Inter-
national Commission on Radiological Protection (ICRP), and the National
Council on Radiation Protection and Measurements (NCRP), and have been
used by the Agency in formulating a policy on relationship between
radiation dose and effect.
"It is the present policy of the Environmental Protection Agency to
assume a linear, nonthreshold relationship between the magnitude of the
radiation dose received at environmental levels of exposure and ill
268
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health produced as a means to estimate the potential health impact of
actions it takes in developing radiation protection as expressed in
criteria, guides, or standards. This policy is adopted in conformity
with the generally accepted assumption that there is some potential ill
health attributable to any exposure to ionizing radiation and that the
magnitude of this potential ill health is directly proportional to the
magnitude of the dose received.
"In adopting this general policy, the Agency recognizes the in-
herent uncertainties that exist in estimating health impact at the low
levels of exposure and exposure rates expected to be present in the
environment due to human activities, and that at these levels, the
actual health impact will not be distinguishable from natural occur-
rences of ill health, either statistically or in the forms of ill health
present. Also, at these very low levels, meaningful epidemiological
studies to prove or disprove this relationship are difficult, if not
practically impossible, to conduct. However, whenever new information
is forthcoming, this policy will be reviewed and updated as necessary.
"It is to be emphasized that this policy has been established for
the purpose of estimating the potential human health impact of Agency
actions regarding radiation protection, and that such estimates do not
necessarily constitute identifiable health consequences. Further, the
Agency implementation of this policy to estimate potential human health
effects presupposes the premise that, for the same dose, potential
radiation effects in other constituents of the biosphere will be no
greater. It is generally accepted that such constituents are no more
radiosensitive than humans. The Agency believes the policy to be a
prudent one.
"In estimating potential health effects, it is important to rec-
ognize that the exposures to be usually experienced by the public will
be annual doses that are small fractions of natural background radiation
to at most a few times this level. Within the United States, the
natural background radiation dose equivalent varies geographically
between 40 to 240 mrem per year. Over such a relatively small range of
dose, any deviations from dose-effect linearity would not be expected to
significantly affect actions taken by the Agency, unless a dose-effect
threshold exists.
"While the utilization of a linear, nonthreshold relationship is
useful as a generally applicable policy for assessment of radiation
effects, it is also EPA's policy in specific situations to utilize the
best available detailed scientific knowledge in estimating health impact
when such information is available for specific types of radiation,
269
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conditions of exposure, and recipients of the exposure. In such situ-
ations, estimates may or may not be based on the assumptions of line-
arity and a nonthreshold dose. In any case, the assumptions will be
stated explicitly in any EPA radiation protection actions.
"The linear hypothesis by itself precludes the development of
acceptable levels of risk based solely on health considerations. There-
fore, in establishing radiation protection positions, the Agency will
weigh not only the health impact, but also social, economic, and other
considerations associated with the activities addressed."
Within the context of the overall policy statement reprinted above,
EPA uses primarily the recommendations of the National Academy of
Sciences Committee on Biological Effects of Ionizing Radiation (BEIR)
(11.1) as expressed in their November 1972 report to arrive at dose-to-
health risk conversion factors. Besides the concept of linearity
expressed in the policy statement, it is further assumed that health
effects that have been observed at dose rates much greater than those
represented in this report are indicative of radiation effects at lower
dose rates. Any difference in biological recovery from precarcinogenic
radiation damage due to low dose rates is neglected in the BEIR health
risk estimates. On the other hand, in some cases, the BEIR risk esti-
mates are based on relatively large doses where cell killing may have
reduced the probability of delayed effects being observed and hence,
underestimate the effects at low doses. The dose-risk conversion
factors that EPA has adopted from the BEIR report are neither upper nor
lower estimates of risk, but are computed on the same basis as the risk
characterized as "the most likely estimate" in the BEIR report, that is
they are averages of the two risk models considered in the BEIR report;
relative and absolute risk.
One must caution against interpreting the product of dose and risk
conversion factor as a prediction of actual number of effects to be
sought out in the real world. The dose conversion factors (from concen-
tration to dose) and the risk conversion factors (dose to effects) yield
estimates of the actual dose and effects which have a considerable
range. For example, the BEIR Committee has made a determination, based
on their evaluation of the increase of the ambient cancer mortality per
rem, that ranges from 100 to 450 deaths per million persons per rem
during a 30-year followup period. EPA has chosen average values to be
used for various dose to health effect conversion factors. When new
information becomes available these factors will be revised.
Dose-risk Conversion Factors
1. Total body dose-risk
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The BEIR Report calculates the excess cancer mortality risk (in-
cluding leukemia mortality) from whole body radiation by two quite
different models. The absolute risk model1 predicts about 100 cancer
deaths per 106 person-rem while the relative risk model2 predicts
between 160 and 450. An average cancer mortality of 300 annually per
106 person-rem would seem to be an appropriate mean for the relative
risk model. The average of the absolute and relative risk models is
about 200 per 106 person-rem. Cancer mortality is not a measure of the
total cancer risk, which the committee states is about twice the risk of
fatal cancer.
Estimated cancer risk from total body irradiation
Cancer mortality = 200 deaths per year for 106 person-rem annual
exposure. Total cancers = 400 cancers per year for 106 person-rem
annual exposure to the total body.
2. Gonadal dose-risk
The range of the risk estimates for genetic effects set forth in
the BEIR report is so large that such risks are better considered on a
relative basis for different exposure situations than.in terms of
absolute numbers. The range of uncertainty for the "doubling dose" (the
dose required to double the natural mutation rate) is 10-fold (from 20
to 200 rad); and because of the additional uncertainties in (1) the
fraction of presently observed genetic effects due to background radi-
ation, and (2) the fraction of deleterious mutations eliminated per
generation, the overall uncertainty is about a factor of 25. The total
number of individuals showing genetic effects such as congenital anom-
alies, constitutional and degenerative diseases, etc., is estimated at
somewhere between 1,800 and 45,000 per generation per rad of continuous
exposure at equilibrium; i.e., 60-1,500 per year if a 30-year generation
time is assumed. This equilibrium level of effect will not be reached
until many generations of exposure have past; the risk to the first
generation postexposure is about a factor of 5 less than the equilibrium
level.
The authors of the BEIR report reject the notion of "genetic death"
as a measure of radiation risk. Their risk analysis is in terms of
early and delayed effects observed post partum and not early abortion,
still births or reduced fecundity. Because of the seriousness of some
Absolute risk estimates are based on the reported number of excess
cancer deaths per rad that had been observed in exposed population
groups, e.g., Hiroshima, Nagasaki, etc.
2Relative risk estimates are based on the percentage increase per
rem in the ambient cancer mortality.
271
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of the genetic effects considered here, e.g., mongolism, the emotional
and financial stress would be somewhat similar to death impact. Indeed,
10 percent of the effects described are those which lead directly to
infant or childhood mortality (fetal mortality is excluded). For some
purposes, this class of genetic effects is considered on the same basis
as mortality.
Estimated serious genetic risk from continuous gonadal irradiation
Total risk = 200 effects per year for 106 person-rem annual exposure
in the U.S. population with a 50-year generation time.
3. Lung dose-risk
Due to the insufficient data for the younger age groups, estimates
of lung cancer mortality in the BEIR report are only for that fraction
of the population of age 10 or more. For the risk estimate made below,
it is assumed that the fractional abundance for lung tumors is the same
for those irradiated at less than 10 years of age as it is for those
over 10. On an absolute risk basis, lung cancer mortality in a popu-
lation would be about 18 deaths per annum per 106 persons irradiated
continuously at a dose rate of 1 rem per year. This is a minimum value.
The BEIR report states that the absolute risk estimates may be too low
because observation times for exposed persons are still relatively short
compared to the long latency period for lung cancer and indeed the NAS
committee report on "Health Effects of Alpha-Emitting Particles in the
Respiratory Tract" (21.2) indicates that the current (1976) estimate is
twice that made in 1972. Furthermore, lung cancer risks calculated on
the basis of the geometric mean of the relative risk is 3.4 times
larger than the estimated absolute risk. Therefore, an average of mean
relative and absolute risk estimates is given in the following dose-risk
estimate.
Estimated lung cancer risk from continuous tung irradiation
Excess lung cancer mortality = 40 deaths per year for 10G person-
rem annual exposure.
4. Thyroid dose-risk
The insult from radioiodines is important only for the thyroid.
The dose to other organs is over an order of magnitude less. Two health
effects follow high level exposures of thyroid tissue to ionizing radi-
ation: benign neoplasms and thyroid cancer. Though the former is a
more common radiation effect, only the risk from cancer is considered
here.
272
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While children are particularly sensitive to radiation damage to
their thyroid glands, thyroid cancer is a serious but usually not a
deadly disease particularly for persons in younger age groups. Mortality
may approach 20 percent in persons well past middle age. It is not
presently known if the radiation-induced cancers which are more frequent
for persons irradiated early in life will follow the same patterns of
late mortality.
The BEIR report provides risk estimates only for morbidity (not
mortality) and only for persons under 9 years of age, i.e., 1.6-9.3
cancers per 106 person-rem years. Additional follow-up on external
irradiation cases, suggests a thyroid malignancy rate of 4/y/106
person-rem (range 1.5-16) and perhaps age at irradiation is not as
important as originally thought (11. S).
Since information in the BEIR report is not sufficient in itself to
estimate the cancer incidence from continuous exposure, tentative risk
estimates for this study are also based on information in other refer-
ences (11.4-11.7) as well as the mean of the BEIR Committee's various
estimates of incidence per rem. Infants and fetuses are probably the
most sensitive group. By weighting the age group sensitivity and using
population percentages for the age groups, a population age-weighted
value was obtained. This estimate will be changed to reflect new
followup data when it is reported in the published literature.
Estimated thyroid aanoer risk
Thyroid cancer risk = 60 excess thyroid cancers per 106 thyroid-
rems.
It is unlikely that the mortality from thyroid cancer would be more
than 5-20 percent of its rate of incidence. As for other radiation
effects, a true measure of the risk from thyroid cancers could be life
shortening, but insufficient mortality data prevents such an approach.
References
(11.1) NATIONAL ACADEMY OF SCIENCES - NATIONAL RESEARCH COUNCIL. The
effects on populations of exposure to low levels of ionizing
radiation, Report of the Advisory Committee on the Biological
Effects of Ionizing Radiation (BEIR), U.S. Government Printing
Office, Washington, D.C. (1972).
2) U.S. ENVIRONMENTAL PROTECTION AGENCY, OFFICE OF RADIATION
PROGRAMS. Health Effects of Alpha-Emitting Particles in
the Respiratory Tract. Report of Ad Hoc Committee on "Hot
Particles" of the Advisory Committee on the Biological Effects
of Ionizing Radiations. National Academy of Sciences-National
Research Council. EPA 520/4-76-013, Washington, D.C. 20460
(October 1976).
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(11.3) NATIONAL CANCER INSTITUTE. Conference on Radiation-Associated
Thyroid Carcinoma. Chicago, 111. (1977) in press.
(11.4) INTERNATIONAL COMMITTEE ON RADIOLOGICAL PROTECTION. The evalu-
ation of risks from radiation, ICRP publication no. 8, Pergamon
Press, New York 11101 (1966).
(11. S) UNITED NATIONS SCIENTIFIC COMMITTEE ON THE EFFECTS OF ATOMIC
RADIATION. "Ionizing Radiation: Levels and Effects," Vol. II,
United Nations Publication E.72.IX.18, New York (1972).
(11.6) U.S. ENVIRONMENTAL PROTECTION AGENCY. Environmental Radi-
ation Protection for Nuclear Power Operations, Proposed
Standards [40 CFR 190], Supplementary Information. Environ-
mental Protection Agency, Washington, D.C. 20460 (October 1976)
(11.7) U.S. ENVIRONMENTAL PROTECTION AGENCY. Environmental Analysis
of the Uranium Fuel Cycle, Part III - Nuclear Fuel Repro-
cessing, EPA-520/9-73-003-D, Office of Radiation Programs,
Environmental Protection Agency, Washington, D.C. 20460
(October 1973).
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Chapter 12 - Nonionizing Electromagnetic Radiation
As its name implies, nonionizing electromagnetic radiation does not
produce ionized particles when it is absorbed by the material of interest.
Absorbed energy is converted to electronic excitation and to molecular
vibration and rotation. The ionization potentials of the principal
components of living tissue (water, and atomic oxygen, hydrogen, nitrogen,
and carbon) are between 11 and 15 electron volts (eV). Michaelson
(12.1) considers 12 eV to be the lower limit for onization in biological
systems, while noting that some weak hydrogen bonds in macromolecules
may have lower ionization potentials. As a point of reference, an
ultraviolet wavelength of 180 nanometers corresponds to an energy of
about 7 eV. Thus, for practical purposes, the nonionizing part of the
electromagnetic spectrum includes the ultraviolet, visible, infrared,
radiofrequency and lower frequency regions. The electromagnetic fields
from electric power distribution at 50 and 60 Hz are included, although
these fields are not radiative in nature.
Because of the increase in the number and power of sources in the
radiofrequency range since 1940, recent interest has focused on nonion-
izing electromagnetic radiation at frequencies below 300 GHz or photon
energies less than 1.24 x 10"3 eV. The voluntary American National
Standards Institute (ANSI) (12.2) exposure standard and the OSHA (12.3)
occupational exposure standard cover the frequency range from 10 MHz to
100 GHz; the Bureau of Radiological Health (BRH) (12.4) microwave oven
performance standard and the proposed BRH (12.5) diathermy performance
standard are for frequencies from 890 MHz to 6 GHz and 890 MHz to 22.25
GHz, respectively. Though there may be limited exposure problems
associated with the use of lasers and some noncoherent light sources, at
the present time we are not aware of manmade sources of nonionizing
electromagnetic radiation operating above 300 GHz which would produce
significant environmental levels. Therefore, this discussion is re-
stricted to frequencies below 300 GHz.
Sources of data
There are two types of data base which are pertinent to analyzing
environmental levels of nonionizing electromagnetic radiation at fre-
quencies below 300 GHz. The first of these consists of computer files
275
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of source location and characteristics that permit the calculation of
expected exposure levels if an appropriate model and sufficient source
parameters are available. The second type of data base consists of
reports on studies of specific sources and the ambient environment.
Until recently, only limited data have been available on the ambient
environment.
The Office of Telecommunications Policy (DTP) assigns operating
frequencies to government users of the electromagnetic spectrum and the
Federal Communications Commission (FCC) assigns frequencies to non-
government users. The most extensive inventory of sources of nonion-
izing radiation in the United States is maintained at the Electromag-
netic Compatibility Analysis Center (ECAC), Department of Defense,
Annapolis, Md. The ECAC Environmental File contains records of govern-
ment and nongovernment communications-electronics equipment. Infor-
mation in the records includes the operational characteristics of the
equipment, its location, and administrative information, such as who is
operating it. There are four subfiles of the Environmental File. These
are the E-file, the Interdepartment Radio Advisory Committee (IRAC)
File, including frequency authorizations of all U.S. government agencies,
the AT&T File, containing the common carrier records, and the FCC File,
with all the FCC-licensed equipment records.
These equipment records are fairly complete with regard to location,
identification, and major characteristics. However, characteristics
which are necessary for sophisticated models are often incomplete or
lacking, so that only simple, approximate models can be used. This type
of information is probably most useful in providing a method for sorting
and ranking potential problem areas which can be studied later in more
detail.
EPA has measured the radiation levels from a number of specific
source types. These include satellite communications systems, acqui-
sition and tracking radars, air traffic control radars, weather radars,
FM radio transmitters, police radar units, and microwave ovens. An
analytical model for predicting levels from sources having parabolic
antennas has been developed and compared to other methods and measured
data. Electric field profiles for 345-, 500-, and 765-kV overhead power
transmission lines have been determined, and a magnetic field profile
has been measured for a 500 kV line.
Techniques and instrumentation are available for the analysis of
fields from most high-power sources. Methods for calculating power
densities have been given by Mumford (12.6) and Tell (12.7). Analysis
of broadcast radiation sources has been given by Tell and Nelson (12.8),
and Tell and Janes (12.9). Satellite communications earth terminals
have been analyzed by Hankin (12.10). Air traffic control radar's
radiation levels have been measured by Tell and Nelson (22.11), and
airborne radars, by Tell and Nelson (12.12) and Tell, Hankin, and Janes
(12.IS). The overall impact of high-power sources based upon measurements
276
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and theoretical analyses has been discussed by Hankin, et al. (12.14,
12.15), The radiation levels on and near a high-power FM radio trans-
mitter tower have been reported by Tell (12.16L Hankin (12.17) has
described the radiation characteristics of police traffic radars. Field
strength measurements of microwave oven leakage at 915 MHz has been
described by Tell (12.18).
The highest power sources are satellite communications stations and
large radars. Both of these source classes use very directive antennas
to achieve extremely high effective radiated powers. Thus, the proba-
bility of being illuminated at any given time by the primary beam of one
of these sources is quite small. Many of these sources are remotely
located and almost all are surrounded by an exclusion area which further
limits the probability of exposure. Site surveys are done for many
sources to delineate operational procedures which will prevent the
inadvertent exposure of occupied areas. Some sources are mechanically
or electrically equipped to limit the pointing directions of antennas or
to reduce or shut off power when occupied areas are scanned. The rota-
tional feature of many radars further reduces the exposure levels.
Nevertheless, a careful examination of the siting and operation of high-
powered sources is required to assure they are installed and operated
safely. When factors such as number of sources, number of persons
potentially exposed, and general operating characteristics and procedures
are considered, broadcast transmitters are the most environmentally
significant category.
High voltage transmission lines
Private citizens, public interest groups, and State agencies have
expressed concern about the potential adverse effects of electric power
at extra-high voltages (EHV), i.e., voltages at or above 345 kilovolts.
Because of these concerns, EPA published a notice in the Federal Register
in 1975, requesting data and information on health and environmental
effects of EHV power transmission (12.19). Over 50 replies totaling
over 6,000 pages were received (12.20). In 1976, a request for proposals
to evaluate and summarize the information received was prepared and made
public. The proposals received in response have been evaluated in
preparation for the award of a contract. Contractual arrangements will
be made in 1977, and the desired evaluation and summary should be available
by the end of the year.
The Agency is represented on the Interagency Advisory Committee on
Electric Field Effects from High Voltage Lines, chaired by ERDA. The
committee's objective is to coordinate federally sponsored efforts
relating to the environmental effects of electric fields from high
voltage transmission lines.
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The Environmental Protection Agency will decide on the need for
guidance or standards relative to discharge currents (electric shock
potential), based on the contracted review of the material submitted to
EPA and the results of the activities of the Interagency Advisory Committee
on Electric Field Effects from High Voltage Lines.
Ambient environmental levels
For the purposes of this discussion, we will broadly define the
general ambient electromagnetic environment to be the electromagnetic
field in the frequency band from 0 to 300 GHz. It results from the
superposition of the field from all sources contributing to the field
at the point of interest. In practice this means all sources which
produce fields greater than the noise level of the detection system
will contribute to the measured level. The actual level may be high
or low depending on the distribution of contributing sources, but in
most cases, should be relatively low when compared to levels in the
main beam of powerful sources. Actual measurements will, for the most
part, cover more restricted frequency ranges than those considered
in the definition. Two types of instruments are used, those which
preserve frequency information and those which integrate across a band
of frequencies. Only a limited amount of data is available on general
ambient environments. A great deal of data has been collected in so-
called noise studies such as that of Toler (12.22). However, these
studies ignore intentional signals and are not useful in estimating
total exposure although they help determine signal amplitude require-
ments for communication and serve as an indicator of the increase in
the use of the electromagnetic spectrum.
In 1969, White Electromagnetics and the Public Health Service
measured peak power densities in the Washington, D.C. area (12.11,12,. 23).
Radiation levels were monitored over the frequency range from 20 Hz to
10 GHz at 10 sites within a 25-mile radius of the city. The highest
levels measured (approximately 10 pW/cm2) originated primarily from AM
broadcast towers and airport radar installations. The accuracy of the
measurements was estimated to be within 15 decibels (dB) in the first
paper and at j^ 10 dB in the second (dB is a logarithmic unit of power
and 10 dB corresponds to one order of magnitude, i.e., a factor of 10).
A similar study over a more restricted frequency range was conducted in
Las Vegas in 1970 by Envall, Peterson, and Stewart (12.24). The maximum
observed power density over the frequency range from 54 to 220 MHz was
0.8 yW/cm2. Ruggera (12.25) studied the changes in electric field
strengths within a hospital before and after the installation of a new
transmitting tower 3,200 feet from the hospital. Measurements were made
in the frequency range from 54 MHz to 656 MHz and the maximum total root
mean square (rms) field strength was about 2 V/m which corresponds to a
far-field power density of about 1 uW/cm2.
278
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As part of a program to determine the need for standards to control
environmental radiofrequency exposure, the U.S. Environmental Protection
Agency (EPA) began measuring levels of radiofrequency radiation in urban
areas in October 1975. Measurements are made principally in urban areas
because sources are concentrated in and around regions of high popu-
lation density (12.26,12.27). Measurements have shown that the principal
sources of environmental radiofrequency radiation are in the broadcast
bands (12.28) with other bands making only minor contributions to the
general environmental levels. Therefore, data are collected in the
seven frequency bands shown in table 12-1.
The measurement system consists of seven antennas, listed in table
12-1, a scanning spectrum analyzer, and a minicomputer. The equipment
is installed in a van equipped with gasoline-powered electrical gener-
ators. Antennas are mounted sequentially on a pneumatically operated,
telescoping mast and elevated 6.4 meters above ground level. After a
predetermined number of scans through the desired frequency range, the
data are corrected for antenna response and both the average root-mean-
square values of the electric field strength and the power density
obtained by integration of the squared field strength values are computed.
The calculated values are displayed on the computer's cathode ray tube,
copied onto thermally sensitive paper, and stored in the computer's
memory. The measurement system, antenna calibration, and the analysis
of system error are described in detail in reference 12.29. Examples of
typical spectra can be found in references 12.9,12.29, and 12.30.
Measurements of environmental radiofrequency field strengths have
been made at 72 sites located in Atlanta, Boston, Miami, or Philadelphia.
The percent of sites having values equal to or less than a given total
power density in the frequency range from 54- to 900-MHz are plotted
against the logarithm of the power density on probability paper in
figure 12-1. Distributions for the land mobile bands, the low VHF-TV
band, and the FM band are also shown. The power density values from
the 0-2 MHz band are not included in this analysis. The FM band con-
tributes the most to environmental radiofrequency exposure between 54-
and 900-MHz. Within this range of frequencies each of the three TV
bands contributes about equally. The land mobile bands make an almost
negligible contribution to the total power density and less active bands
would make even smaller contributions. The maximum power density at any
site summed over all bands was 2.5 yW/cm2. Four sites or about 6 percent
fell in the range of 1 to 2.5 yW/cm2 so that some of the population is
potentially exposed to values in excess of 1 yW/cm2.
Population exposure
An estimator of population exposure'must combine information on the
distribution of radiofrequency levels with the distribution of popu-
lation to provide numbers of people exposed at various levels. The
population data base which was used here has been described elsewhere
(12.31), but briefly, it consists of the population count for each of
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Table 12-1. Antennas used for environmental
radiofrequency measurements
Frequency
(MHz)
Use
Antenna
0-2
VLF communications and AM
standard broadcast
Active vertical monopole
54-88
88-108
150-162
174-216
Low VHP television broadcast
FM broadcast
VHF land mobile
High VHF television broadcast
Two horizontal orthogonal
dipoles
Three orthogonal dipoles
Vertical coaxial dipole
Two horizontal orthogonal
dipoles
450-470
470-806
UHF land mobile
UHF television broadcast
Vertical coaxial dipole
Horizontal polarized
directional log periodic
280
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80
to
LJJ
^ 70
CO
LL. 60
O
50
(—
z ..
uj 40
U
UJ
a.
20
10
u •
<• «
1 •
LAND ' .> j. •
MOBILE ' / .* • *
\ i«4 ••' •''
\ 1 •' *
\ 4*
\ • f • •'
• ./ *' *
/ .• *
* • .
LOW ' ;* ;
VHF-TV / . /*
\ 1* ' •'
V / :\
/ :" / \
1 FM ." V \
: ,/ V r \
f .* ./ TOTAL
• i . •
* - ' .'
• •
»• .• ;
i •
• •
4
-6 -5 -4 -3 -2 -1 0
LOG S; S= POWER DENSITY in uW/cm2
Figure 12-1. Percent of sites having values equal to or less than a given total
power density in the frequency range from 54 to 900 MHz
250,000 census enumeration districts (CED) in the United States along
with the geographic coordinates of the approximate population centroid
for the CED. The population of an area is considered to be concentrated
at a set of discrete points. The total power density from all sources
at each of these discrete points is determined and the population exposed
at the various levels is summed.
The model
data collected
data from each
plotted as log
shape of this
regardless of
ily by an addi
field strength
distance in mi
for determining the radiofrequency fields is based on
with the measurement system described above. The measured
source were observed to generally fall on a parabola when
(power density) versus log (distance). Furthermore, the
parabola was approximately the same for all sources,
source parameters, differing from source to source primar-
tive constant. Therefore, an empirical expression for the
E, in dB above 1 yV/m, as a function of log D (D =
ies), was chosen:
E = -10 (log D)2 - 20 log D + C
where C is a source specific constant. To determine the field strength
at any point (e.g., at a CED centroid) the three measurement sites
nearest the point of interest are determined, and from the measured data
at these three points, a value of the constant C for each source is
determined. Substitution of the distance from the source to the point
281
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into the expression for E yields the required field strength estimate
for that source. The individual source contributions can be appropri-
ately summed to get the total exposure.
This approach was applied to each CED centroid in the four metro-
politan areas where measurements had been made (12.32). The population
for each CED was assigned the exposure determined for its centroid
location. This information was sorted according to exposure ranges, and
the results are presented in figure 12-2 which shows the fraction of the
population in the four metropolitan areas (total population = 8.3 million)
exposed to various levels. The median power density is 0.014 yW/cm2.
Less than one percent of the population is exposed to values greater
than 1 yW/cm2.
This model for population exposure does not account for compli-
cations such as daily movements of the population within an area, exposures
at heights greater than 6 meters where exposures can be higher due to
nonuniform antenna radiation patterns, for any attenuation effects of
typical buildings, or for times when sources are not transmitting. The
results are simply the population residing in areas where an unobstructed
measurement 6 meters above ground would result in the indicated values.
In addition to the general environmental measurements, data were
collected at a few selected sites in tall buildings which were located
.99
.95
.9
VI
O
°-
x
§
.4
.1
.05
01
CITIES: BOSTON
ATLANTA
MIAMI
PHILADELPHIA
-5 -4 -3 -2 -1 0
LOG S (S = POWER DENSITY IN (J.W/CM2)
Figure 12-2. Fraction of population exposed as a function of power density
282
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near transmitters in Chicago, Miami, and New York. The upper floors of
some buildings may be higher than a transmitter on a neighboring building,
and thereby be exposed to the main beam of the transmitter.
These building measurements were performed using a tuned half-wave
dipole connected to a portable spectrum analyzer. Signal amplitudes
displayed on the spectrum analyzer were photographed and the values
obtained were corrected for antenna factors. The tuned di poles were
previously calibrated against a set of National Bureau of Standards
calibrated dipoles (12.29). The resulting field strength, E (volts per
meter), may be converted to equivalent far- field power density, S
(yW/cm2), through the relation
EW")32
The measurements show that power density levels in some areas of
the upper floors of tall buildings can be much higher than measurements
made at ground level. At windows facing transmitters, with blinds
raised, the maximum levels observed in selected buildings in New York,
Miami, and Chicago were 32, 97, and 66 yW/cm2 respectively, and consisted
primarily of radiation from FM radio and UHF-TV transmitters. These
levels should not be regarded as typical of tall buildings, or even
typical of these selected buildings. Structural materials and window
blinds can significantly reduce actual levels inside the buildings.
These preliminary results will be further characterized in future studies,
Discussion
There is a large difference in the exposure standards of the United
States and the U.S.S.R., those of the latter being much more restrictive.
The level for unlimited occupational exposure in the Soviet Union is 10
yW/cm2, and the proposed environmental level is 1 yV!/cm2. Controversy
continues over the validity of the Soviet standard. The Soviet standard
was adopted in Poland in 1961, pending an independent evaluation. In
1972, the Polish standard was revised and the occupational level was set
at 200 yW/cm2, and the environmental limit was set at 10 yW/cm2 (12.33).
Research is now underway in this country and elsewhere to determine
and assess any possible biological effect of long-term exposure to low
levels of nonionizing radiation and to examine the validity of the
present occupational exposure standard of 10 mW/cm2. Also of concern
are the effects of high peak power, low average power, pulsed radiation
and the questions of the need for and how to develop standards for the
frequency range below 10 MHz where there is currently no exposure
standard. Four types of overlapping exposure can be distinguished: (1)
exposure in the general environment to intentional signals from the
broadcast services, radars, leakage radiation, and other sources, (2)
occupational exposures, (3) exposure to leakage radiation from consumer
devices such as microwave ovens, and (4) intentional medical exposures.
Occupational exposure is subject to control by OSHA. Intentional
283
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medical exposure is given at the discretion of a physician, but a
performance standard is now being developed by the Food and Drug Admin-
istration for leakage and scatter from microwave diathermy units. There
is no direct control of environmental exposure from microwave diathermy
apparatus. Indirect controls of environmental exposures are the limi-
tation put on effective radiated power by the FCC, their requirement for
posting areas about domestic satellite stations where levels exceed 10
mW/cm2, and the operational procedures employed in using both government
and nongovernment sources. Also, any telecommunications system planned
for purchase by the government, as a condition for spectrum approval, is
reviewed by IRAC-OTP to assess among other factors whether levels in
excess of 10 mW/cm2 will occur and whether operational measures have
been provided to insure that people are not exposed above this level.
Two types of environmental exposure can be distinguished. One is
the relatively high radiation level from high power sources such as some
radars and satellite communications stations where the power density in
the useful beam can exceed that thought to be safe for human occupancy
even outside the boundary of the facility (12.15). The problems assoc-
iated with such sources are recognized and instrumentation and techniques
for analyzing exposure from them are available. The other type of
environmental exposure arises from the superposition of the fields from
many sources at different frequencies. This exposure may be high or low
depending on the location and types of sources contributing to the
exposure and includes the specific source problem as a special case.
Nonionizing environmental radiation data are needed to interpret the
results of current biological effects research and establish the pre-
dominant frequencies in the environment so that future research for the
validation of standards can be appropriately directed.
Summary
General environmental surveys have been completed in seven cities
in the Eastern United States. The data and population exposure impli-
cations for the first four of these are presented here and analysis is
continuing on the other three. The measurement program will now continue
in several cities in the Western United States.
The results to date suggest that probably 99 percent of the urban
population is exposed at levels which would be permitted even under the
restrictive proposed Soviet standard of 1 yM/cm2. The general environ-
mental data cannot be used to estimate the levels to which the remaining
1 percent of the population is exposed. Further information will require
a detailed analysis of specific sources and a detailed knowledge of the
locations of the persons exposed to such sources.
284
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(12.24)
(12.25)
(12.26)
(12.27)
(12.28)
(12.29)
(12.30)
(12.31)
(12.32)
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288
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Glossary
Absorbed dose (D) - The energy imparted to a unit mass of matter by
ionizing radiation. The unit of absorbed dose is the rad. One rad
equals 100 ergs per gram (See rad).
Accelerator - A device for increasing the kinetic energy of charged
elementary particles, for example, electrons or protons, through
the application of electrical and/or magnetic forces.
AEC - U.S. Atomic Energy Commission - In 1975, the Atomic Energy
Commission was divided into two new agencies. The regulatory portion
became the Nuclear Regulatory Commission, and the reactor development
portion became part of the Energy Research and Development Adminis-
tration.
Agreement States - Those States which, pursuant to Section 274 of the
Atomic Energy Act of 1954, as amended, have entered into an
agreement with the NRC for assumption of regulatory control of
byproduct, source, and small quantities of special nuclear materials.
Before approving an agreement State, NRC must determine that the
State's radiation control program is compatible with NRC's regulatory
program and is adequate to protect public health and safety.
Body burden - The amount of radioactive material present in the body
of a man or an animal.
Boiling water reactor (BWR) - A reactor in which water, used as both
coolant and moderator, is allowed to boil in the core. The resulting
steam can be used directly to drive a turbine.
By-product material - Any radioactive material (except source material
or fissionable material) obtained during the production or use of
source material or fissionable material. It includes fission
products and many other radioisotopes produced in nuclear reactors.
Cosmic radiation - Radiation of many sorts but mostly atomic nuclei
(protons) with very high energies, originating outside the earth's
atmosphere. Cosmic radiation is part of the natural background
radiation. Some cosmic rays are more energetic than any manmade
forms of radiation.
Curie (Ci) - The special unit of activity. One curie equals 3.7 x 1010
nuclear transformations per second.
Daughter - A nuclide formed by the radioactive decay of another nuclide,
which in this context is called the parent.
289
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Decommissioning - The process of removing a facility or area from oper-
ation and decontaminating and/or disposing of it or placing it in a
condition of standby with appropriate controls and safeguards.
Decontamination - The selective removal of radioactive material from a
surface or from within another material.
Diathermy - The generation of heat in tissues for medical or surgical
purposes by electric currents.
Disposal - The planned release or placement of waste in a manner that
precludes recovery.
Dose - A general term denoting the quantity of radiation or energy
absorbed. For special purposes it must be appropriately qualified.
If unqualified, it refers to absorbed dose.
Dose equivalent (#) - A quantity used in radiation protection. It
expresses all radiations on a common scale for calculating the
effective absorbed dose. It is defined as the product of the absorbed
dose in rads and certain modifying factors (The unit of dose equi-
valent is the rem).
Dose rate - Absorbed dose delivered per unit time.
$8.00 reserves - Ore that can be mined and processed for $8.00 a pound.
Electron volt (eV) - A unit of energy equivalent to the energy gained by
an electron in passing through a potential difference of one volt.
Larger multiples of the electron volt are frequently used: KeV
for thousand or kilo electron volts: MeV for million or mega electron
volts (1 eV - 1.6 x 10"12 erg).
Energy Research and Development Administration (ERDA) - In 1975, the
Atomic Energy Commission was divided into two new agencies. The
regulatory portion became the Nuclear Regulatory Commission and the
reactor development portion became part of the Energy Research and
Development Administration.
Exposure - A measure of the ionization produced in air by x or gamma
radiation. It is the sum of the electrical charges on all ions of
one sign produced in air when all electrons liberated by photons in
a volume element of air are completely stopped in air, divided by the
mass of the air in the volume element. The special unit of exposure
is the roentgen.
External radiation - Radiation from a source outside the body.
Flux density (neutron) - A term used to express the number of neutrons
entering a sphere of unit cross-sectional area in unit time. For
neutrons of given energy, the product of neutron density and speed.
290
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Frequency - Number of cycles, revolutions, or vibrations completed in
a unit of time (See Hertz).
Fuel cycle - The complete series of steps involved in supplying fuel
for nuclear power reactors. It includes mining, refining, the
original fabrication of fuel elements, their use in a reactor,
chemical processing to recover the fissionable material remaining
in the spent fuel, reenrichment of the fuel material, refabrication
into new fuel elements, and management of radioactive waste.
Genetically significant dose (GSD) - The gonadal dose which, if received
by every member of the population, would be expected to produce the
same total genetic effect on the population as the sum of the indiv-
idual doses that are actually received. It is not a forecast of
predictable adverse effects on any individual person or his/her
unborn children.
Gonad - A gamete-producing organ in animals; testis or ovary.
Half-life - Time required for a radioactive substance to lose 50 percent
of its activity by decay. Each radionuclide has a unique half-life.
Hertz - Unit of frequency equal to one cycle per second, generally
applied to nonionizing radiation.
High-level liquid waste - The aqueous waste resulting from the operation
of the first-cycle extraction system, equivalent concentrated wastes
from a process not using solvent extraction, in a facility for pro-
cessing irradiated reactor fuels. This is the legal definition used
by ERDA; another definition used at the ERDA Hanford Reservation for
its waste, is: fluid materials, disposed of by storage in underground
tanks that are contaminated by greater than 100 microcuries per mini-
liter of mixed fission products or more than 2 microcuries per milli-
liter of cesium-137, strontium-90, or long-lived alpha emitters.
High temperature gas-cooled reactor (HTGR) - A reactor in which the
temperature is great enough to permit generation of mechanical power
at good efficiency using gas as the coolant.
ICRP - International Commission on Radiological Protection.
Intermediate-level liquid waste - Fluid materials, disposed as a result
of Hanford operations, which contain from 5 x 105 microcuries per
milliliter to 100 microcuries per milliliter of mixed fission products,
including less than 2 microcuries per milliliter of cesium-137,
strontium-90, or long-lived alpha emitters.
Internal radiation - Radiation from a source within the body as a
result of deposition of radionuclides in body tissues by ingestion,
inhalation, or implantation.
291
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lonization - The process by which a neutral atom or molecule acquires a
positive or negative charge.
Isotopes - Nuclides having the same number of protons in their nuclei,
and hence the same atomic number, but differing in the number of
neutrons, and therefore, in the mass number. Almost identical
chemical properties exist between isotopes of a particular element.
Licensed material - Source material, special nuclear material, or by-
product material received, possessed, used, or transferred under a
general or special license issued by the U.S. Energy Research and
Development Administration or a State.
Linear accelerators - A device for accelerating charged particles. It
employs alternate electrodes and gaps arranged in a straight line,
so proportioned that when potentials are varied in the proper
amplitude and frequency, particles passing through the waveguide
receive successive increments of energy.
Low-level liquid waste - Fluid materials that are contaminated by less
than 5 x 10 5 microcuries per milliliter of mixed fission products.
Man-rem - The product of the average individual dose in a population
times the number of individuals in the population. Syn: Person-
rem.
Maximum permissible dose equivalent (MPD) - The greatest dose equivalent
that a person or specified part of the body shall be allowed to
receive in a given period of time.
Millfeed - The ore and other material introduced into the milling
process.
Millirem (mrem) - One-thousandth of a rem (See rem).
Muon - An elementary particle classed as a lepton, with 207 times the
mass of an electron. It may have a single positive or negative
charge.
NRC - U.S. Nuclear Regulatory Commission: In 1975, the Atomic Energy
Commission was divided into two new agencies. The regulatory portion
became the Nuclear Regulatory Commission and the reactor development
portion became part of the Energy Research and Development Adminis-
tration.
292
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Nuclide - A species of atom characterized by the constitution of its
nucleus. The nuclear constitution is specified by the number of
protons (Z), number of neutrons (N) and energy content; or alterna-
tively, by the atomic number (Z), mass number A = (N + Z), and atomic
mass. To be regarded as a distinct nuclide, the atom must be capable
of existing for a measurable time. Thus, nuclear isomers are separate
nuclides, whereas promptly decaying excited nuclear states and
unstable intermediates in nuclear reactions are not so considered.
Permissible dose - The dose of radiation which may be received by an
individual within a specified period with expectation of no signif-
icantly harmful result.
Person-rem - The product of the average individual dose in a population
times the number of individuals in the population. Syn: man-rem.
Polarization - In electromagnetic waves, refers to the direction of the
electric field vector.
Population dose - The sum of radiation doses of individuals and is
expressed in units of person-rem (e.g. if 1,000 people each received
a radiation dose of 1 rem, their population dose would be 1,000
person-rem).
Power density - The intensity of electromagnetic radiation power per
unit area expressed as watts/cm2.
Pressurized water reactor (PWR) - A power reactor in which heat is
transferred from the core to a heat exchanger by water kept under
high pressure to achieve high temperature without boiling in the
primary system. Steam is generated in a secondary circuit. Many
reactors producing electric power are pressurized water reactors.
Quality factor (Q) - The linear-energy-transfer-dependent factor by
which absorbed doses are multiplied to obtain (for radiation
protection purposes) a quantity that expresses-on a common scale for
all ionizing radiations-the effectiveness of the absorbed dose.
Rad (Acronyn for radiation absorbed dose) - The special unit of absorbed
dose of ionizing radiation. A dose of one rad equals the absorption
of 100 ergs of radiation energy per gram of absorbing material (See
absorbed dose).
Radioactive decay - Disintegration of the nucleus of an unstable nuclide
by spontaneous emission of charged particles and/or photons.
Radioisotope - A radioactive isotope. An unstable isotope of an element
that decays or disintegrates spontaneously, emitting radiation.
Radwaste - Waste materials that are contaminated with radioactive materials,
293
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Rem - The special unit of dose equivalent. The dose equivalent in rems
is numerically equal to the absorbed dose in rads multiplied by the
quality factor (Q), and the product of any other modifying factors
(N) at the point of interest in tissue. ICRP has presently assigned
a value of 1 for irradiations by external sources.
Roentgen (R) - The special unit of exposure. One roentgen equals 2.58 x
10 "* coulomb per kilogram of air (See exposure).
Skin dose (Radiology) - Absorbed dose at center of irradiation field on
skin. It is the sum of the dose in air and scatter from body parts.
Skyshine - Radiation emitted through the roof of the shield (or unshielded
roof) that scatters back to ground level due to its deviation by the
atmosphere.
Solid wastes (Radioactive) - Either solid radioactive material or solid
objects that contain radioactive material or bear radioactive surface
contamination.
Source material - In the Code of Federal Regulations (CFR), any material
except special nuclear material, which contains 0.05 percent or more
of uranium, thorium, or any combination of the two.
Special nuclear material - In the Code of Federal Regulations (CFR),
this term refers to plutonium-239, uranium-233, uranium containing
more than the natural abundance of uranium-235, or any material
artificially enriched in any of these substances.
SWU - Standard work units.
Transuranium - Nuclides having an atomic number greater than that of
uranium (i.e., greater than 92).
Technologically enhanced natural radioactivity (TENR) - Naturally radio-
active nuclides whose relationship to the location of persons has
been altered through man's activities such as by the activities of
mining, tunneling, development of underground caverns, development of
wells, and travel in space or at high altitudes.
Terrestrial radiation - Radiation emitted by naturally occurring radio-
nuclides such as potassium-40; the natural decay chains uranium-238,
uranium-235, or thorium-232; or from cosmic-ray induced radionuclides
in the soil.
Type A and Type B quantities - Legally established maximum amounts of
radioactive materials which can be contained in Type A and Type B
packages, respectively. Precise definitions are listed in 49 CFR
173.389(1), however, basically the radionuclides are divided into
seven groups according to their radiotoxicity and relative potential
hazard in transportation. Each of these groups then has a maximum
amount assigned depending on the type of package to be used to ship it.
294
-------
Type A packaging - Containers designed to maintain their integrity,
i.e., not allow any radioactive material to be released and to keep
the shielding properties intact, under normal transportation condi
tions. The test conditions which must be met are defined in 49 CFR
173.398b and include heat, cold, reduced air pressure, vibration,
water spray endurance, free drop, penetration, and compression
standards.
Type B packaging - Containers designed to meet the standards established
for hypothetical transportation accident conditions, as well as
meeting the Type A packaging standards, without reducing the effectiveness
of the shielding or allowing releases in excess of those enumerated
in 49 CFR 173.398c(l). The standards to be met by Type B packages,
in addition to the Type A standards, are defined in 49 CFR 173.398c(2)
and include puncture, thermal, water immersion, and higher free
drop tests.
UNSCEAR - United Nations Scientific Committee on the Effects of Atomic
Radiation.
Volt (V) - The unit of electromotive force (1 volt = 1 watt/1 ampere).
Whole body dose - The radiation dose to the entire body.
International numerical multiple and submultiple prefixes
Multiples
and
submultiples
Prefixes
Symbols
1018
1015
1012
109
106
103
102
101
10"1
10"2
10"3
10"6
10"9
10"12
10~15
10'18
exa
peta
tera
giga
mega
kilo
hecto
deka
deci
centi
mi 1 1 i
micro
nano
pi co
femto
atto
E
P
T
6
M
k
h
da
d
c
m
y
n
P
f
a
295
*U.S. GOVERNMENT PRINTING OFFICC . 1977 0-720-335/6004
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