United States
Environmental Protection
Agency
Radiation
Office of
Radiation Programs
Washington, D.C. 20460
EPA 520/1-84-005
September 1984
Occupational Exposure to
Ionizing Radiation in the
United States
A Comprehensive Review
for the Year 1980 and a
Summary of Trends for the
Years 1960-1985
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EPA 520/1-84-005
OCCUPATIONAL EXPOSURE TO IONIZING RADIATION
IN THE UNITED STATES
A Comprehensive Review for the Year 1980
and a Summary of Trends for the
Years 1960-1985
Shigeru Kumazawa
DeVaughn R. Nelson
Allan c.B. Richardson
Office of Radiation Programs
U.S. Environmental Protection Agency
Washington, D.C. 20460
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FOREWORD
The Environmental Protection Agency carries out a continuing
program to evaluate exposure of the public to radiation, to recommend
radiation protection guidance for the use of Federal agencies, to
promulgate environmental radiation standards and regulations, and to
advise the states on radiation protection matters, so as to protect
public health and to assure environmental quality. The Agency's
responsibility for radiation protection guidance to Federal agencies
is derived from Executive Order 10831 and Public Law 68-373 (42 USC
2021(h)), which charge the Administrator of EPA to "...advise the
President with respect to radiation matters, directly or indirectly
affecting health, including guidance for all Federal agencies in the
formulation of radiation standards and in the establishment and execu-
tion of programs of cooperation with States." This study was carried
out in support of that responsibility.
The number of workers exposed to ionizing radiation has increased
significantly since Federal radiation protection guidance for occupa-
tional exposure was first issued in 1960. This report is the second of
its kind; it provides a comprehensive review of exposure of workers for
the year 1980 and a summary overview of trends for the period 1960-1985.
We acknowledge with particular gratitude the support of Shigeru
Kumazawa, Senior Scientist, by the Japan Atomic Energy Research Insti-
tute and the Japanese Government during the years 1982 and 1983. This
support enabled his invaluable contributions, which encompassed the
major portion of the analyses contained in this report.
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We would like to be informed of any errors or omissions in this
report and of additional sources of information. Comments and sugges-
tions for improvements in future reports are also welcomed. These
should be addressed to Allan C.B. Richardson. Chief. Guides and Criteria
Branch (ANR-460), Office of Radiation Programs, U.S. Environmental
Protection Agency, Washington. D.C. 20460.
Sheldon Meyers, Acting Director
Office of Radiation Programs
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ACKNOWLEDGMENTS
We are grateful to many people for their contributions to this
review of occupational exposure. In particular, we acknowledge the help
of Barbara Brooks of the Nuclear Regulatory Commission (NEC), who made
available much unpublished exposure data for terminated workers as well
as other data for NRC licensees. In addition, the following persons
supplied exposure data or interpretative information essential to this
report: Donald Barber, Ph.D., University of Minnesota; Colonel Johan
Bayer, U.S. Air Force; Commander Tom Bell, U.S. Navy; Gordon Born,
Purdue University; William Bottomley, D.D.S., Georgetown University
Hospital; J.F. Brice, Naval Nuclear Propulsion Program; Henry Briggs,
Indiana University; Donald C. Brown, D.D.S., Rockville, Hd.; William
Bugg, Ph.D., University of Tennessee; Wendell Carriker, Department of
Transportation (DOT); James Carroll, University of Tennessee; Walter
Cool, NRC; Larry Crabtree, D.D.S., Center for Devices and Radiological
Health (CDRH); Dennis Dean, Illinois Department of Nuclear Safety;
Fred Eggelston, U.S. Postal Service; Roland Finston, Ph.D., Stanford
University.
Also, Arthur Gass, occupational Safety and Health Administration
(OSHA); Aurel Goodwin, Ph.D., Mine safety and Health Administration
(MSHA); Vance Grant, Ph.D., Department of Education; Carol Gregory,
Purdue University; E. David Harward, Atomic Industrial Forum; Wallace
Hinckley, Radiological Health Program of the State of Maine; Thomas G.
Hobbs, National Bureau of Standards; Vila Hunter, Veterans Administra-
tion (VA); David Johnson, CDRH; G. Wayne Kerr, NRC; S.K. Kleff, MSHA;
Phil Lee, University of Missouri; Jeannine Lewis, CDRH; Larry L. Lloyd,
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Montana Department o£ Health & Environmental Sciences; Captain S.A.
Martinelli, U.S. Navy; Bette Murphy, Ph.D., Battelle; Major Robert E.
Nelson, U.S. Air Force; Maury Neuwig, Illinois Department oE Nuclear
Safety.
Also, Douglas Parker, MSHA; Philip Plato, Ph.D., University of
Michigan; Gene Proctor, National Aeronautics and Space Administration;
Lee Quidley, VA; Richard Rawl, DOT; Harvey Rudolph, Ph.D., CDRH; Tom
Schneider, Department of Education; Jim Shotts, University of Missouri;
George Siebert, Department of Defense; Max Slade, MSHA; Colonel George
E.T. Stebbing, U.S. Army; John Taschner, CDRH; John H. Tolan, University
of Missouri; Theo Tscomis, Federal Aviation Administration; Anthony Tse,
NRC; Edward J. Vallario, Department of Energy; J.C. Vi11forth, CDRH;
Sheldon Weiner, Ph.D., OSHA; Harold Wyckoff, Ph.D., National Council on
Radiation Protection and Measurements; Michael Zender, Ph.D., California
State University-Fresno; Paul Ziemer, Ph.D., Purdue University; and
Robert A. Zoon, National Institutes of Health.
Finally, we are indebted to many people who contributed to the
production of this report. Among these, special appreciation is due
Philip A. Cuny, who assisted in the computer analysis of occupational
data and three-dimensional graphic displays; Mary Anne Culliton and
Duane W. Schmidt, who assisted in editing the report; and Eleanor T.
Jones and Tywanna Grimes who prepared the manuscript.
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CONTENTS
Page
Foreword ill
Acknowledgements v
Summary xi
I. INTRODUCTION 1
II. BACKGROUND FOR THE ASSESSMENT OF 1980 OCCUPATIONAL EXPOSURE. . 9
A. General Background 9
1. Types of Radiation Exposure 9
2. Sources of Exposure 10
3. Personnel Monitoring 11
B. Regulatory Authorities and Standards in 1980 12
1. Federal Authorities 14
2. State Authorities 11
3. Indirect Regulatory Authorities 17
4. Radiation Protection Standards 18
C. Summary of Monitoring and Reporting Requirements 19
III. DATA SOURCES AND ANALYSIS METHODS 23
A. Categories of Workers 23
B. Assessment of the Number of Workers 26
1. Medicine 27
2. Industry 28
3. Miscellaneous Occupations 28
C. Assessment of the Exposure of Workers 29
1. Federal Exposure Data 30
2. Commercial Exposure Data 32
D. Analysis of the Exposure Data 33
1. Dose Distributions 34
2. Age Distributions 35
3. Cumulative Doses 36
vii
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CONTENTS (Continued)
Page
IV. SUMMARY OF NATIONAL OCCUPATIONAL EXPOSURE FOR 1980 39
A. Principal Results 39
B. The Number of Workers and Collective
Dose by Work Category 41
C. Dose Distributions 41
D. Age Distributions 47
V. REVIEW OF TRENDS IN OCCUPATIONAL EXPOSURE 53
A. Trends in Major Indices of Occupational Exposure 54
1. Number of Potentially Exposed Workers 54
2. Sources of Occupational Exposure 54
3. Mean and Collective Doses to Workers 59
4. Collective Dose Versus Number of Workers
and Mean Annual Dose 61
B. Trends in Dose Distributions 64
1. Distributions of Annual Doses to Workers 64
2. Distributions of Collective Doses to Workers 68
3. Projected Dose Distributions in 1985 under
a 5-rem Constraint 68
C. Estimated Cumulative Doses 74
1. Mean Cumulative Doses 74
2. Maximum Cumulative Doses 76
VI. ERROR AND UNCERTAINTY 81
A. introduction 81
B. Methodology 84
C. Number of Workers 84
D. Dose/Age Distributions 87
E. Conclusions 89
REFERENCES 91
viii
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CONTENTS (Continued)
APPENDICES
APPENDIX A - ESTIMATING THE SIZE OF THE WORK FORCE
APPENDIX B - DOSE DISTRIBUTION ESTIMATES
APPENDIX C - ADDITIONAL INFORMATION AND RESULTS FOR 1980
APPENDIX D ~ FEDERAL AGENCY EXPOSURE DATA FOR 1980
APPENDIX E - OCCUPATIONAL EXPOSURE SUMMARIES FOR 1960,
1970, AND 1975
APPENDIX F - THE HYBRID LOGNORMAL AND JOHNSON SB DISTRIBUTIONS
APPENDIX G - FEDERAL RADIATION PROTECTION GUIDANCE
TABLES
Page
1. Major statutes and regulations pertaining to occupational
exposure of workers to radiation 15
2. Description of occupational categories and subcategories ... 24
3. Summary of 1980 occupational exposure data from Federal
agencies 31
4. Summary of exposure of workers to radiation, 1980 40
5. Summary of exposure of some additional groups of individuals
to radiation, 1980 42
FIGURES
1. Authorities for radiation protection of U.S. workers 13
2. Model of worker employment for estimating cumulative dose. . . 36
3. Distributions of potentially exposed workers and their
collective doses by work category, 1980 43
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FIGURES (Continued)
Page
4. Potentially exposed workers and their collective doses
by dose range, 1980 44
5. Potentially exposed workers and their collective doses
by dose range and work category, 1980 46
6. Potentially exposed workers and their collective doses
by age range, 1980 48
7. Potentially exposed workers and their collective doses
by age range and work category, 1980 50
8. Estimated number of potentially exposed workers,
1960 to 1985 55
9. Indices related to the numbers of potentially exposed
workers in medicine, industry, and the nuclear fuel
cycle, 1960 to 1985 57
10. Mean annual dose and collective dose to potentially
exposed workers, 1960 to 1985 60
11. Trends in mean annual dose, collective dose, and the number
of potentially exposed workers, 1960 to 1985 62
12. Dose distributions for potentially exposed workers,
1960 to 1985 65
13. Collective dose distributions for exposed
workers, 1960 to 1985 69
14. Projected dose distribution for potentially exposed
workers for 1985, with and without a 5-rem constraint. ... 71
15. Number of potentially exposed workers exceeding a
given dose, 1960 to 1985 73
16. Mean cumulative doses for various groups of
terminated workers 75
17. Cumulative doses, in descending order of magnitude, for
terminated employees of NRC licensees, 1977 to 1982 73
18. Schematic of basic methodology for assessing
occupational exposure to radiation 35
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SUMMARY
Occupational exposure to ionizing radiation in the United States
Cor 1980 and for the period 1960-1980 may be summarized as follows:
1980
About 1.32 million U.S. workers were potentially exposed to
ionizing radiation. About half of these workers received measurable
doses that were distinguishable from normal background radiation.
About 44% of all workers were employed in medicine, 23% in industry,
16% in government, and 11% in the nuclear fuel cycle.
The mean annual dose was 0.11 rem for all workers, with 15%
exceeding this dose. About 6%, 2%, and 0.1% of all workers received
doses greater than 0.5, 1.5, and 5 rems, respectively. The mean dose
was 0.23 rem for all measurably exposed workers, with 20% of these
exceeding this dose. Of all workers measurably exposed, those at
nuclear power reactors received the highest mean dose - 0.65 rem.
The mean dose to all male workers (0.16 rem) was more than triple
that to all female workers (0.05 rem). The median ages of male and
female workers were 33 and 28, respectively.
The collective dose for all workers was about 150,000 person-rems.
About 65% of this collective dose was incurred by the 5% of workers
that received between 0.5 and 5 rems. About 70%, 40%, and 5% of this
collective dose was incurred by workers with doses greater than 0.5,
1.5, and 5 rems, respectively. Workers in the nuclear fuel cycle
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accounted for the largest share of the collective dose (37%), followed
closely by those in medicine (27%) and industry (25%).
About 55% of all potentially exposed workers were male; these
workers received 80% of the total collective dose. Seventy-five percent
of the collective dose to women was to workers in medicine and 55% was
to women less than 30 years old.
The mean cumulative dose for workers terminated during the period
1969-1982 was estimated to be on the order of one rem. Maximum cumula-
tive doses for workers terminated during this period were estimated to
be about 100 reins.
1960-1980 Summary of Trends
The number of potentially exposed workers in the United States was
about one-half million in 1960 and has doubled every 14 or 15 years
since that time. Expressed differently, while the mean annual growth
rates of the labor force and the U.S. population were 2% and 1.2%,
respectively, that of potentially exposed workers was about 5% during
that period.
The mean annual dose to potentially exposed workers decreased by
almost a factor of 2 between 1960 and 1980. It decreased by about
0.03 rem every 5 years between 1965 and 1975, but has decreased at a
slower rate since 1975. The fraction of workers receiving less than
the mean annual dose has remained constant at about 85%.
The collective dose to U.S. workers fluctuated around 120,000
person-rems between 1965 and 1975 and increased to about 150,000
person-rems between 1975 and 1980.
Since 1960, the distribution of doses above 1 rem has changed
substantially, with a large decrease in the fraction of workers
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approaching or exceeding 5 rems. Since 1965, the absolute number of
workers exceeding 3 rems has decreased, While the number exceeding
1 rem has increased, and the number exceeding 2 rems has remained
relatively constant.
The fraction of collective dose due to workers exposed above 1.5
rems has decreased from 53% in 1965 to 40% in 1980; for doses above 5
rems, this fraction has decreased from 31% in 1965 to 5% in 1980.
Since 1970 the growth rate of collective dose was greatest for the
nuclear fuel cycle. However, efforts to avoid exposures greater than
5 rems have resulted in the fraction of collective dose above 5 rems to
be second smallest among the major categories of workers; only govern-
ment workers have done better.
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I. INTRODUCTION
Occupational exposure to ionizing radiation in the United States is
governed by regulations established by a wide variety of Federal and
State agencies. To assure uniform protection of workers, these regula-
tions are governed by a single set of guides, called Radiation Protection
Guidance for Federal Agencies, which is issued by the President (see
Appendix G).
This system was established in 1959 by President Eisenhower through
creation of the Federal Radiation Council (FRC), whose function it was
to make recommendations to the President regarding radiation protection.
In 1960 the FRC recommended the first Federal guidance for occupational
exposure to ionizing radiation (FRC60a). That guidance has been the
basis for all subsequent Federal and State regulations limiting occupa-
tional exposure to such radiation. In 1970, President Nixon created the
U.S. Environmental Protection Agency (EPA) through a reorganization of
Federal agencies (Reorganization Plan No. 3 of 1970), and in so doing
abolished the FRC and transferred its functions to SPA. EPA proposed
revisions to Federal occupational guidance in 1981; however, at the
time this report was prepared those recommendations were still pending
(EPA81).
Early estimates of the numbers of U.S. workers and their doses from
exposure to ionizing radiation were made by the FRC when it developed
the 1960 Federal occupational guidance (FRC60b). Those estimates were
limited to workers exposed in medical applications of x rays, in indus-
trial radiography, and in Atomic Energy Commission facilities. In 1972,
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EPA published somewhat more extensive estimates of exposure to workers
(K172). in 1974, we began a review of Federal guidance for limiting
occupational exposure. As part of that review, we published In 1980
our first comprehensive analysis of occupational exposure in the united
States (Co80). That summary covered exposures for the year 1975 and,
in addition to previously assessed groups of workers, also included
estimates for groups of workers for which government agencies do not
maintain records.
In the present report we have updated the 1975 analysis to 1980.
In addition, we have examined historical trends in the number and expo-
sure of workers during the 20-year period from 1960, when the first
Federal occupational guidance was promulgated, to 1980, and have made
projections for the year 1985.
We have tried to include all persons who are potentially exposed
to ionizing radiation at their work places. Unfortunately, there is no
simple index of information, such as a Bureau of Labor Statistics Stan-
dard Industrial classification (Sic) code, that identifies such workers.
Although we have not attempted to formulate an explicit definition of
workers "potentially exposed to ionizing radiation," we have included
essentially all groups of workers known to be associated with signifi-
cant sources of ionizing radiation.
As noted above, radiation protection in the United states is
administered by a number of Federal and State authorities. Although
this arrangement has functioned effectively to limit the exposure of
workers, no centralized system has been established to maintain exposure
records for workers. As a result, our assessment of exposure of workers
has depended upon data from a variety of sources. We have relied upon
both complete and incomplete monitoring records to characterize various
groups of workers. Because of the differences in these data, we have
had to use, in many instances, modeling of numbers of workers and their
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exposure distributions to provide reliable and consistent results. We
use the term model in the broad sense to mean a system of postulates,
data, and inferences used to mathematically estimate numbers and doses
of groups of workers. The details of our approaches to this modeling
are given in the appendices to this report.
Our review of occupational exposure has also included an historical
analysis. The current patterns of occupational exposure have resulted
from many influences, including changes in the types and utilization of
sources of ionizing radiation, and the evolving practice of radiation
protection as governed by limits provided by Federal occupational
radiation protection guidance and Federal and State regulations, and
recommendations of organizations such as the International Commission on
Radiological Protection and the National Council on Radiation Protection
and Measurements. However, recent influences, such as greatly increased
attention to maintenance of exposures as low as reasonably achievable
(ALARA), shortness of supply of workers in some occupations, increased
awareness of radiation risks, and changing perceptions of the accepta-
bility of occupational risks, have also played important roles. Recent
studies of occupational exposure have examined some of these factors
(As81; Bro83a,83b; Dr81; EPRI81; Ma81; UNSCEAR82).
To interpret occupational exposure data correctly, one must
consider why workers are monitored. From a regulatory point of view,
monitoring data usually result from efforts to minimize dose accumula-
tion or to demonstrate compliance with dose limits for individuals.
Since conservative (upper bound) values can suffice to simply show
compliance, some data may provide overly conservative values of dose
to workers. However, all Federal and State regulations now require
realistic measurement of exposure of workers entering certain areas or
likely to exceed certain (usually fairly low) doses. In addition,
workers exposed at very low levels often are monitored only because of
the simplicity of badging all workers in a facility or of the need to
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assure workers that they receive little or no exposure. As a result,
the representativeness of monitoring data for workers with low exposure
may vary because of differences in monitoring practices.
The interpretation of historical monitoring data is also affected
by changes in the sensitivity and calibration of radiation dosimeters.
The increased sensitivity of today's dosimeters allows detection of
doses near background, in cases where previously no dose would have been
reported. Uncertainties in calibration, especially for data obtained
many years ago, lead to uncertainty in doses reported. There have been
few requirements for adherence to dosimetry performance standards in the
United States. The National Sanitation Foundation adopted a standard
for film badge services in 1966 (NSF66) that only a few States (Illinois,
Montana, and New York) required dosimetry services to satisfy before
offering services in those States. However, recent approval by the
American National Standards Institute of a standard for testing personnel
dosimetry performance has had wide support (ANSI83) and should improve
the reliability of personnel monitoring records. Although that standard
is presently voluntary, the NRC has recently proposed its adoption as a
regulatory requirement (NRC84). Only broad interpretations of historical
exposure records can be made without examining these factors. We have
not attempted to correct for such factors for this report.
Finally, other factors, such as the type of radiation measured and
placement of dosimeters, can be significant. Our data base for occupa-
tional exposure of U.S. workers consists of reported personnel dosimeter
readings, and we present the results of our analysis in terms of the same
unit - the dose equivalent - that is assigned to these dosimeter readings.
Dosimeter readings reflect worker exposure to various types and levels of
ionizing radiation. However, although dosimeters may respond reproducibly
to exposure of the dosimeter at its location on the worker, they may not
necessarily provide accurate estimates of the dose to the worker. There
are two principal sources of uncertainty: 1) the energy response of the
dosimeter and 2) the source-to-dosimeter-to-worker geometry. Current
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dosimeters can provide adequate measurements of dose from x rays and
gamma rays over an energy range from about 50 keV to a few MeV. When
the exposure of workers involves large components of low-energy scattered
radiation, such as for diagnostic medical x rays, appropriate calibration
of dosimeters is necessary to obtain accurate estimates of the dose to
the whole body. In addition, dosimeters are generally calibrated with
unidirectional fields, even though actual exposures may involve a much
different geometry of exposure due to the spatial relationship between
the source and the worker. However, although large errors can be made
in estimating doses to individuals (ANSI83; Ch78a,78b; ICRP82; ICRU76;
NCRP78), we believe that the characteristic values obtained for large
groups of workers are much less subject to the errors expected for spe-
cific individuals. An exception may be groups of workers exposed to
predominately low energy radiation. In summary, it is important to
recognize that this report deals with reported dosimeter readings, which
may or may not accurately reflect actual doses to workers. Throughout
this report, we use the terms "exposure" and "dose" to mean the values
obtained as dosimeter readings.
One further aspect of the data used in this study is that the
records we used to estimate "annual" exposures include the exposures
of all workers, regardless of what fraction of the year they worked
and were monitored. Such an analysis accurately represents the exposure
of workers for that year. This was the objective of our study, and these
results can be directly compared with those in national and international
reports. However, the mean doses estimated in this report are smaller
than would be estimated for workers who worked and were monitored for a
full year. Our results should not be used, therefore, to infer the ann-
ual exposure of full-time employment in any of the categories or subca-
tegories of work examined. Rather, they represent the average over all
full- and part-time workers. We made a cursory examination of the dif-
ference to be expected between our results and exposure of full-time
workers by examining a limited sample of 1980 dosimetry data. The mean
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doses for full-time workers range from 0-50 percent higher than those
for all workers for the several groups examined. The results of this
limited survey are given in Appendix C.
We have estimated, for the period 1960-1980, the number of workers
potentially exposed to radiation and the distribution of their doses for
five major categories of workers: those in medicine, industry, the
nuclear fuel cycle, government, and miscellaneous occupations (education
and transportation). From these distributions the mean dose, collective
dose, and collective dose distribution for all workers were derived. We
have also similarly examined smaller subcategories of workers when it
was feasible.
Doses to workers were characterized according to age and sex for
1975 and 1980 from a large sample of commercial dosimetry data. These
data provided the basis for estimating the age distributions for both
male and female workers as well as their dose and collective dose
distributions as a function of age.
We were particularly interested in examining dose distributions and
historical trends to assess the effect of efforts to achieve exposures
that are below regulatory limits and as low as reasonably achievable
(ALARA). For this purpose, we fitted the hybrid lognormal distribution
model (HLN model) to exposure data. These investigations are discussed
in Chapter V.
Our methods for estimating the numbers of workers and their
exposures are believed to be better than those used in our earlier
study; that is, the values in this report should be more reliable and
consistent. This is principally due to improved models for estimating
the numbers of workers and the distribution of annual doses to various
kinds of workers. We examined estimates of numbers of workers and dose
distributions, for various levels of aggregation of workers, using
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several statistical methods and, where possible, compared the results of
these estimation methods. We have the most confidence in our estimates
for specific types of workers for which government agencies require or
maintain comprehensive personnel dosiraetry records. However, we made
estimates for all significant categories of workers, even when there was
a paucity of data. Similarly, projections of worker dose distributions
and collective dose distributions by age and sex were based on data of
variable completeness and accuracy.
Several groups of individuals, including students, visitors to DOE
facilities, underground miners, and flight crews and attendants on
passenger aircraft, are summarized separately in this report because of
the nature of their job, exposure, or their uncertain status as workers.
There are also a few identified groups of exposed workers not included
in this study. One group consists of some Federal, and most State and
local regulatory personnel. Dose records for some of these workers,
such as NRC inspectors of commercial nuclear power stations, are included
in the exposure data for those stations. Other inspectors, such as those
for HSHA, OSHA, and State programs were not assessed in this report.
There are also some groups of workers in some mineral extraction indus-
tries who are exposed to low levels of radiation and are generally not
monitored. One example is the phosphate industry where, for a few
workers, maximum doses have been estimated to range from 10 to 300 mil-
lirera (mrem) per year (EPA76). The above workers will be considered in
further detail in future studies.
In addition, relatively few workers are monitored for internal
exposure. These data are not normally reported to Federal or State
agencies unless an overexposure has occurred. Because of its scarcity,
internal exposure data are not presented or analyzed in this report.
There are also insufficient data to generate a complete national summary
of exposure of extremities (hands and feet). However, commercial extrem-
ity data are analyzed in Appendix C to obtain a rough measure of such
exposure.
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With these qualifications, we believe that this report on occupa-
tional exposure of workers to ionizing radiation in the united states
provides a comprehensive and reliable summary for the year 1980 and
overview for the years 1960 to 1985.
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II. BACKGROUND FOR THE ASSESSMENT OF 1980 OCCUPATIONAL EXPOSURE
A. General Background
1. Types of Radiation Exposure
From a regulatory point of view, worker exposure to external or
internal sources of radiation is generally examined for compliance
against the whole body, partial body (including organs), and extremity
radiation protection guides prescribed by Federal guidance (see Appen-
dix G). External irradiation of the whole body is by far the most
common type of exposure; it is primarily this type of exposure from
x-ray, gamma-ray, and neutron sources that is assessed in this report.
Internal exposure occurs when radioactive material is inhaled,
ingested, or absorbed into the body. Such material may concentrate in
specific organs or tissues. Compared to external exposure, relatively
few workers are exposed to or monitored for internal exposure. In
addition, except for uranium miners, such monitoring data are currently
not normally reported, and therefore available for analysis, unless an
overexposure occurs. A special case of Internal exposure is provided
by exposure of miners to inhaled radon decay products. We separately
summarize these data for underground miners in Chapter IV; these data
are further discussed in Appendix C.
Extremity exposures are exposures of the forearms and hands, or
lower legs and feet, almost invariably from an external radiation
source. These exposures typically occur when the extremities are close
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to radioactive sources while the torso and head are shielded by a bar-
rier or protected by distance. A crude national summary of extremity
exposure based on our sample of commercial dosimetry data is given In
Appendix C.
2. Sources of Exposure
sources of occupational exposure include: naturally-occurring
*
radioactive materials (including "source materials" - uranium and
*
thorium); "special nuclear materials" (plutonlum, uranium-233, and
*
enriched uranium); radioactive "byproduct materials" (radionuclides
produced as a result of the fission of special nuclear materials);
accelerator-produced radioactive materials; and electronic devices
that emit ionizing radiation (e.g., x rays, electrons, protons, and
neutrons).
Occupational exposure from source materials occurs principally
In uranium mining and milling operations of the nuclear fuel cycle.
The handling, fabrication, and use of special nuclear materials lead
to exposure of workers in nuclear fuel cycle and nuclear weapons
operations.
Radioactive byproduct materials are those yielded In or made
radioactive by exposure to the radiation Incident to the process of
producing or utilizing special nuclear materials. They include acti-
vation products from nuclear reactors and plutonium-berylllum neutron
sources, but not from other neutron sources, such as californium-252
or accelerators. Exposure to byproduct sources of radiation is the
principal source of exposure in nuclear power reactor operations, but
also occurs In practically every other major group of workers consid-
ered in this report. Only dental, chiropractic, and uranium mine and
*Terminology for these radioactive materials is as defined in the
Atomic Energy Act of 1954, as amended.
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milling workers are not likely to receive exposure from such sources.
Byproduct sources are used extensively for diagnostic and therapeutic
purposes in medicine. Major industrial uses include well logging,
nondestructive testing, tracer techniques, thickness gauging, and
industrial radiography.
Naturally-occurring radioactive materials are of either primordial
or cosmic ray origin. Naturally-occurring carbon-14 and tritium origi-
nate from cosmic rays, while potassium-40, radon-222, and radium-226
are examples of primordial materials, as are source materials. Occupa-
tional exposure from primordial materials occurs primarily as a result
of such technological activities of man as mining, in addition to the
mining operation itself, the milling of uranium and phosphate ores, for
example, produces waste tailings that are sources of radiation exposure.
The extraction and use of radium in medicine and for luminous dials led
to significant occupational exposure in the past, but now leads to very
little.
Electronically-produced radiation means radiation produced by
equipment when it is electrically energized (e.g., by x-ray machines,
electron microscopes, and particle accelerators). Examples are x rays,
electrons, and protons. Some of these sources are widely used in
medical and industrial applications. Accelerator-produced radioactive
materials, such as technetium-99, are produced in increasing quantities
for use in medical and research applications. Even though occupational
exposures from these sources are controlled by shielding and/or on-off
procedures, such exposures lead to the majority of doses for many
medical and industrial workers.
3. Personnel Monitoring
Personnel dosimeters commonly used to monitor exposure to pene-
trating radiation include radiation sensitive emulsions (film badges),
thermoluminescent dosimeters (TLDs), and nuclear track detectors. TLDs
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are small, reusable plastic chips that are readily processed. Film
badges are small and also provide a permanent record, but are not
reusable nor as readily processed. Nuclear track detectors, which
are used for monitoring some neutron exposures, are not reusable and
are more difficult to process.
Dosimeters are generally capable of providing reasonably accurate
measurements of dose to workers for radiations of known energy and for
known irradiation geometries. For example, recent performance testing
of U.S. processors of TLD and film badge dosimeters in a pilot study
demonstrated fairly good (and improving) performance under ideal test
conditions (NRC80). Dosimeter performance was tested for high- and
low-energy photon, beta, and neutron radiations. For tests that were
made in 1978, 18% of individual dosimeter readings deviated from the
correct value by less than 50%; for tests made in 1982, 89% deviated
less than 50%. The mean deviations of all dosimeter readings from the
correct values in these tests were 24% in 1978 and 19% in 1982. Com-
pared to these general results, commercial data used in this study
exhibited significantly better average performance (a mean deviation
of about 6% in 1982). We note that these mean deviations are small
compared to other uncertainties associated with interpretations of the
significance of occupational doses, such as prediction of the risk to
health associated with a given dose. Further details of the above
performance tests of dosimeters are given in Appendix C.
B. Regulatory Authorities and Standards in 1980
No single agency regulates the exposure of workers in the United
States. This responsibility is carried out by five Federal regulatory
agencies with direct jurisdiction over exposure of workers or sources
of radiation exposure, by many Federal agencies who govern exposure of
their own (or their contractors') employees, and by various agencies of
the fifty States (Figure 1). Some State agencies regulate exposure of
12
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EPA (1, 2)
RECOMMENDATIONS
PRESIDENT
OCCUPATIONAL RADIATION
STATES
(3)
I, I,
NRC
(2)
ITT
APPROVED STATES
OSHA
(4)
AGREEMENT
STATES
NRC
AGREEMENT,
OSHA
APPROVED.
AND STATE
PROTECTED
WORKERS
GOVERNMENT
AND NON-
GOVERNMENT
LICENSEE
WORKERS
MSHA
(5)
NRC LICENSEES
ALL WORKERS
NOT
OTHERWISE
PROTECTED
PRESIDENTIAL
GUIDANCE
PROTECTION GUIDANCE
NON-AEAI2)
DOD
(2)
MINE
AND MILL
WORKERS
EXPOSURES
DOE
(21
MILITARY,
AND DOD
CIVILIAN AND
CONTRACTOR
WORKERS
DOT AND
USPS
(6.7)
OTHER
FEDERAL
AGENCIES
W
DOE AND DOE
CONTRACTOR
WORKERS
AGENCY
AND AGENCY
CONTRACTOR
WORKERS
REGULATORS
OF WORKER
EXPOSURE
HHS
(8)
TRANSPORT
AND POSTAL
WORKERS
REGULATORS
OF SOURCES
ONLY
SELF REGULATORS
(GOVERNMENT AND
CONTRACT WORKERS)
WORKERS
USING
ELECTRONIC
PRODUCT
RADIATION
SOURCES
PROTECTED
WORKERS
(1) Executive Order 10831.
(2) Atomic Energy Act of 1954, as amended.
(3) State enabling legislation and State laws.
(4) Occupational Safety & Health Act of 1970.
(5) Federal Mine Safety & Health Act of 1977, as amended.
(6) Department of Transportation Act of 1974.
(7) Postal Reorganization Act of 1970.
(8) Radiation Control for Health & Safety Act of 1968.
> Federal Radiation Protection Guidance
• Regulations
Figure 1. Authorities for radiation protection of U.S. workers.
-------
workers according to agreements with two of the Federal regulatory
agencies, and some regulate independently. In this section we iden-
tify the government agencies, their major legislative authorities, the
sources of radiation covered, and exposure standards and regulations
as they existed in 1980 (Table 1). As noted earlier, these various sets
of standards and regulations are each governed by Federal Radiation Pro-
tection Guidance and are therefore essentially similar in their net
effect on worker exposure.
1. Federal Authorities
The Atomic Energy Act of 1954, as amended, provides for Federal
control of three types of radioactive material: 1) source material;
2) special nuclear material; and 3) byproduct material. This authority
was originally administered by the former Atomic Energy Commission
(ABC). The Energy Reorganization Act of 1974 transferred regulatory
authority for nonfederal use of these materials from the former ABC to
the Nuclear Regulatory Commission (NRC).
The NRC licenses all users of significant quantities of special
nuclear material, except for military applications by the Departments
of Defense and Energy. About half of the States have agreements with
the NRC (in 1980 there were twenty-six such "Agreement States") that
give them limited authority to license users of source or byproduct
materials. Such users in the remaining States are licensed directly by
the NRC. All NRC licensees are governed by the occupational exposure
regulations contained in Title 10, Part 20, of the Code of Federal
Regulations (10 CFR 20). NRC Agreement States are required to have
regulations comparable to those at 10 CFR 20.
Some special nuclear material operations at former ABC facilities
need no NRC license. The Energy Reorganization Act of 1974 transferred
regulatory authority over the AEC's research laboratories and other
14
-------
Table 1. Major statutes and regulations pertaining to occupational exposure of workers to radiation
Agency
Legislative authority
Sources of radiation
Regulations
Environmental Protection Agency
State Radiation Control Programs
Nuclear Regulatory Commission
and their Agreement States
Department of Labor
Occupational Safety & Health Admin.
and their approved States
Mine Safety & Health Administration
Department of Transportation
U.S. Postal Service
Department of Health & Human
Services
FEDERAL GUIDANCE
Executive Order 10831 and Atomic Energy All
Act of 1954, as amended, through the
Reorganization Plan No. 3 of 1970
REGULATORS OF COMMERCIAL WORKERS' EXPOSURE
State enabling legislation All
Atomic Energy Act of 1954, as amended
Source, special nuclear,
and byproduct materials
Occupational Safety & Health Act of 1970 Electronic devices,
Federal Mine Safety & Health Act of 1977
REGULATORS OF SOURCES ONLY
Department of Transportation Act of 1974
18 USC 1716(a),(b) and 39 USC 401(2),
3001
Radiation Control for Health & Safety
Act of 1968
Natural ly-occurr ing
radioactive
Source, special nuclear,
and byproduct materials;
and NARM(b)
Federal Radiation
Protection Guidance
SSRCR Part
10 CFR 20
29 CFR 1910.96
30 CFR 57.5-37 to 47
49 CFR 108-109 and
174-177
Radioactive material(<•) Postal Publication 6
Electronic devices
21 CFR 1020
Department of Energy
Department of Defense
Other Federal Agencies
SELF REGULATORS (GOVERNMENT AND CONTRACTOR WORKERS)
Atomic Energy Act of 1954, as amended All
Atomic Energy Act of 1954, as amended All
Occupational Safety & Health Act of 1970 All
DOE 5480. 1A
DOD Instruc.
No. 6055.8
Various
Suggested Regulations for Control of Radiation, or a close equivalent, in most cases (HHS83).
(^Natural and accelerator-produced radioactive materials.
(c)"Radioactive Material," means "any material having a specific activity greater than 0.002 microcuries per
(49 CFR 173.403(y)).
gram"
-------
facilities to the Energy Research and Development Administration, which
in 1977 became the Department of Energy (DOE). Contractors who operate
DOE laboratories and facilities are exempt from NRC requirements when
they use special nuclear materials to develop weapons or reactors for
military vehicles or vessels. The DOE has its own internal regulations
that govern such occupational exposure (DOE81).
The Department of Defense (DOD) is also exempt from NRC licensing
requirements when it uses special nuclear materials for weapons or
propulsion. The Army, Navy, and Air Force have developed their own
regulations for occupational exposure consistent with uniform DOD
instructions (DOD83).
The Federal Coal Mine Health and Safety Act of 1969 (Public Law
91-173) assigned to the Department of Interior (DOI) regulatory author-
ity over occupational safety and health protection in all mines and
mills except over radiation protection in NRC-licensed uranium mills.
That DOI jurisdiction covered exposure to gamma rays and radon decay
products in all mines and mills (except NRC-licensed uranium mills).
However, the Federal Mine safety and Health Act of 1977 (Public Law
95-164) amended the 1969 Act to establish the Mine Safety and Health
Administration (MSHA), to transfer safety and health functions of DOI
to the Department of Labor (DOL), and to extend regulatory authority to
uranium mills. The MSHA and the NRC have a memorandum of understanding
that governs their mutual regulatory responsibilities (MSHA79). The
applicable occupational exposure regulations remain those specified at
30 CFR 57.
The Occupational Safety and Health Act of 1970 established broad
authority for the regulation of occupational exposure by the Occupa-
tional Safety and Health Administration (OSHA) of the DOL. This
authority applies to all occupational exposure of workers except that
regulated by the NRC or MSHA. Federal agencies must establish programs
that are consistent with OSHA standards. The OSHA also approves "State
16
-------
Plans" under Which State authorities may regulate occupational exposure.
Twenty-two States had approved State Plans in 1980; eleven of those were
also NEC Agreement States. An OSHA-approved State Plan must contain
standards that are as effective as OSHA standards. The OSHA's occupa-
tional exposure regulations are specified at 29 CFR 1910.96.
2. State Authorities
As noted above, most States operate under NRC agreements and/or
OSHA-approved State Plans. In general, Federal standards prevail unless
the States' are more protective.
As a uniform guide for formulating regulations, many States use the
"Suggested State Regulations for Control of Radiation" (SSRCR). These
are prepared by the Conference of Radiation Control Program Directors
with support from the EPA, the Department of Health and Human services
(HHS), and the NRC. Part D of the SSRCR contains standards for radia-
tion protection of workers that are equivalent to those at 10 CFR 20.
3. Indirect Regulatory Authorities
The Department of Health and Human Services and the U.S. Postal
Service have no direct authority for regulating exposure of workers,
but indirectly affect occupational exposure through other regulations.
The Department of Transportation also indirectly regulates worker
exposure.
The secretary of HHS has authority under the Radiation Control for
Health and Safety Act of 1968 to regulate the manufacture of electronic
radiation-generating devices to assure their safe performance. The
Center for Devices and Radiological Health (CDRH) (formerly the Bureau
of Radiological Health) of HSS issues regulations (21 CFR 1020) that
limit radiation leakage from electronic source components and assem-
blies.
17
-------
The Department of Transportation (DOT) indirectly regulates occupa-
tional exposure through its packaging, storage, and carriage regulations
for radioactive materials. The DOT has authority under the Department
of Transportation Act of 1974 to regulate, except for postal shipments,
the interstate transport of all radioactive materials, including source,
special nuclear, and byproduct materials (49 CFR Part 174-177). In
addition, the Federal Aviation Administration (FAA) of the DOT regulates
holders of FAA operating certificates for passenger operations who use
x-ray systems for inspecting carry-on articles. These regulations
require the certificate holder to use x-ray machines that meet the per-
formance standards at 21 CFR 1020.40 or guidelines published by the FDA
(38 FR 21442; August 8, 1973). Operators of these x-ray systems are
required to receive training in radiation safety and to be monitored in
accordance with regulations at 49 CFR 108.17 and 49 CFR 129.26 for
domestic and international travel operations, respectively.
The U.S. Postal Service indirectly affects occupational exposure
through limitations on the type and quantity of radioactive material
that can be shipped in the U.S. mail. Postal shipments are covered by
regulations in Postal Service Publication 6, "Radioactive Materials,"
September 1983; Domestic Mail Manual (124.37) and Publication 52 incor-
porate brief summaries of these regulations.
4. Radiation Protection Standards
Federal Radiation Protection Guidance (25 FR 4402; May 18, 1960)
specifies the numerical doses or exposures which Federal agencies should
not normally allow to be exceeded. These are called Radiation Protec-
tion Guides (RPGs). In addition, the guidance specifies that Federal
agencies should make every effort to encourage maintenance of radiation
doses "...as far below these guides as practicable," (this is commonly
rephrased as "as low as reasonably achievable," or ALARA). The RPG for
occupational exposure of the whole body permits doses up to 3 rents per
18
-------
quarter (or 12 rems per year) within an overall cumulative limit of
5(N-18) rems, where N is the age of the worker (see Appendix G for the
entire set of RPG values). NEC regulations conform to this guidance.
DOB and DOD regulations are more strict; they limit exposure of the
whole body to 5 rems per year. OSHA regulations are comparable to
those of the NRC, but do not require that doses be maintained ALARA.
MSHA regulations require that no person in underground mines receive an
exposure to radon decay products in excess of the RPG for such exposure
(4 working level months in any calendar year; see Appendix G), and that
annual individual gamma radiation exposure not exceed 5 rems. DOT and
U.S. Postal Service regulations are designed to keep the maximum annual
exposure below the RPG for whole-body exposure of the general public
(500 millirems) for most situations, because the general public, as
well as workers, can be exposed. Major specific regulations for each
Agency are cited in Table 1.
C. Summary of Monitoring and Reporting Requirements
All radiation protection regulations containing numerical limits
for worker exposure also contain requirements for personnel monitoring.
These are typically equivalent to the NRC regulation (10 CFR 20.202)
which requires monitoring of any individual who enters a restricted
area and is likely to receive a whole-body dose in any calendar quarter
of more than 312.5 millirems (i.e., 25% of 1.25 rems) or who enters
locations defined as high radiation areas. Personnel monitoring is
optional for workers likely to receive a lower dose, and actual practice
in such situations varies widely.
Reporting requirements for monitored exposures exist for only some
workers. That is, even when monitoring is required, the data are not
necessarily reported or otherwise available. The NRC, for example,
requires annual monitoring reports for four types of licensees where the
generally highest exposures occur. On the other hand, the OSHA has no
requirement for reporting radiation exposures unless its standards are
exceeded.
19
-------
The NRC requires an annual report of personnel monitoring from four
categories of licensees: commercial nuclear power reactors; industrial
radiographers; fuel processors, fabricators, and reprocessors; and manu-
facturers and distributors of specified quantities of byproduct material
(10 CFR 20.407). This report must include a statistical summary of
doses to individuals for whom personnel monitoring was either required
or voluntarily provided during the calendar year. The NRC summarizes
these data in annual occupational radiation exposure reports. In 1978,
the NRC initiated a special two-year study for the years 1978 and 1979
during which all licensees were required to provide the above described
statistical summaries of occupational exposure information (43 PR 44827;
Sept. 29, 1978). Results from these summaries have been used in this
report (Bro81,82).
MSHA monitoring, recordkeeping, and reporting requirements for
gamma radiation and radon decay products in underground mines are
listed at 30 CFR 57. Gamma radiation surveys are required in all
underground mines where radioactive ores are mined. Dosimeters are
required for all persons exposed and cumulative records are required
when the average gamma radiation level exceeds 2.0 milliroentgens per
hour.
The MSHA requires an initial measurement of radon decay products
in the exhaust air of all mines, in uranium mines, if levels in excess
of 0.1 Working Level* (WL) are found, levels are determined every one or
every two weeks at random times in all active working areas, depending
upon whether they are in excess of or less than 0.3 WL, respectively.
Where uranium is not mined, the required frequency is once every three
*"Working level" (WL) means any combination of the short-lived radon
decay products in one liter of air that will result in the ultimate
emission of l.SxlO5 MeV (million electron volts) of potential alpha
energy. Exposure to these decay products over a period of time is
expressed in terms of "working level months" (WLM). Inhalation of air
containing a radon-decay-product concentration of 1 WL for a working
month (173 hours) is defined as an exposure of 1 WLM.
20
-------
months for levels between 0.1 and 0.3 WL and once every week for levels
in excess of 0.3 WL.
Mine operators are required to measure radon decay product levels
and to estimate and record individual exposures of all mine personnel
working underground wherever uranium is mined. Where uranium is not
mined, recordkeeping is required only for concentrations of radon decay
products in excess of 0.3 WL. (Once recordkeeping has commenced for
nonuranium miners, individual estimates may be discontinued below 0.3
WL, provided that a miner has not accumulated more than one-twelfth of
a WLM times the number of months worked in that calendar year.) Mine
operators report required data for all personnel annually.
The DOE requires personnel monitoring where the potential exists
for a worker to receive a dose or dose commitment in any calendar
quarter in excess of 10 percent of the quarterly regulation (e.g.,
3 rems for the whole body). Contractors provide monitoring data that
the DOE summarizes in an annual report on radiation exposure of DOE
and DOE contractor employees (DOE76-82).
The DOD's personnel monitoring requirements parallel those of the
DOE. The DOD also maintains permanent exposure records, but most expo-
sure data are not published. However, the Naval Nuclear Propulsion
Program, which monitors radiation exposures to Navy and civilian person-
nel from Naval nuclear propulsion plants and their support facilities,
publishes comprehensive exposure information annually (R182. Sc83).
All States have personnel monitoring requirements. The NRC
Agreement and/or the OSHA-approved Plan States, numbering 37, have
requirements that workers likely to exceed twenty-five percent of 1.25
rems per quarter be monitored, in 1980, the remaining 13 States also
required monitoring of persons within controlled or restricted areas or
of persons routinely exposed. South Dakota (except for dental workers)
and Illinois require monitoring of all persons routinely exposed to
21
-------
radiation, but this can be discontinued if monitoring shows exposures
are less than about 25% of the limits. Only Illinois, of all the
States, requires reporting of dose records for all individuals who are
monitored.
22
-------
III. DATA SOURCES AND ANALYSIS METHODS
In determining the occupational exposure of U.S. workers, we
analyzed data of varying degrees of completeness. For some groups of
workers within or regulated by Federal agencies, nearly complete data
exist for both the numbers of workers and their exposures. For other
groups of workers we used models to interpret the available data and to
estimate these quantities. This chapter provides a general description
of data used to assess occupational exposure in 1980 and the methods
used to analyze these data. Appendix A contains more detailed informa-
tion on the methods used to estimate the numbers of potentially exposed
workers. Appendix B contains more detailed information on data used to
determine the exposure of these workers.
A. Categories of Workers
We have grouped workers into five major categories: medicine,
industry, the nuclear fuel cycle, government, and miscellaneous
(Table 2). These groups are further subdivided, where possible, into
more detailed occupational subcategories which range from specific
professional groups to entire industrial sectors. For example, the
data available permitted characterization of workers in dentistry,
private medical practice, hospitals, veterinary medicine, chiropractic
medicine, and podiatry as separate subcategories of medical workers.
However, we could subdivide workers in industry into only one specific
subcategory (industrial radiography) and two broad subcategories (manu-
facturing and distribution of radiation sources, and other industrial
users of radiation sources).
23
-------
Table 2. Description of occupational categories and subcategories
Category/Subcategory
Description
MEDICINE
Dentistry
Private Practice
Hospital
Veterinary Medicine
Chiropractic Medicine
Podiatry
INDUSTRY
Industrial
Radiography
Manufacturing and
Distribution of
Radiation sources
Other Industrial
Users of Radiation
Sources
NUCLEAR FUEL CYCLE
Nuclear Power
Reactors
Fuel Fabrication
and Reprocessing
Uranium Enrichment
Nonfederal occupations involving medical
diagnostic or therapeutic use of naturally-
occurring, byproduct, and accelerator-produced
radioactive materials, and/or electronic sources
of ionizing radiation.
Dentists, dental hygienists,
assistants.
and dental
Physicians, nurses, technologists, etc., in
private or group/clinic practices (generally
privately owned).
Physicians, nurses, technologists, and medical
physicists at nonfederal hospitals (military and
Veterans Administration hospitals are included
in Government category).
Veterinarians and assistants.
Chiropractors and assistants.
Podiatrists and assistants.
Occupations that entail exposure from radio-
nuclide and electronic sources in industry and
private enterprise other than the practice of
medical sciences.
Nuclear Regulatory Commission (NRC), NRC
Agreement State Licensee, and industrial x-ray
radiographers.
Occupations associated with the manufacture,
delivery, or installation of brachytherapy,
radiopharmaceutical, and electronic sources of
radiation.
Other users of radionuclide and electronic
sources for purposes such as nondestructive
testing, well-logging, and thickness gauging.
All nuclear fuel cycle occupations except
uranium mining.
Maintenance, refueling, inspection, and reactor
operations.
Processing, fabrication, and reprocessing of
reactor fuels.
Uranium enrichment activities at DOE contractor-
operated facilities.
24
-------
Table 2. Description of occupational categories and subcategories
(Continued)
Category/Subcategory
Description
NUCLEAR FUEL CYCLE (Continued)
Nuclear Waste
Management
Uranium Mills
GOVERNMENT
Department of
Defense
Department of Energy
Other Federal
Government
MISCELLANEOUS
Education
Transportat ion
Low-level waste disposal. Nongovernment disposal
operations only: includes removal, transporta-
tion, storage, or burial of byproduct wastes.
NRC-licensed uranium mills.
Occupations involving exposure to ionizing radia-
tion of government and nongovernment workers in
government operations. Includes government-owned
and contractor-operated, Veterans Administration
and military medical, and Civil Defense
facilities.
Medical, special nuclear material and Nuclear
Navy (ships and shipyards) operations.
Department of Energy (DOE) and DDE-contractor
operations.
Veterans Administration, National Institutes of
Health, National Aeronautics and Space Adminis-
tration, National Bureau of Standards, and
Public Health Service*.
Occupations involving radiation exposure in
education and transportation.
Faculty and staff involved with radiation sources
at colleges, universities, technical schools,
and community colleges.
Personnel involved in freightage of radioactive
materials and in airline baggage checks.
ADDITIONAL GROUPS
Underground Miners
Visitors (DOE)
Students
Flight Crews and
Attendants
Underground miners exposed to radon decay
products and gamma radiation.
Visitors to DOE facilities.
Students exposed while attending classes and/or
performing research work.
Flight crews and attendants on passenger airlines,
*Workers in various agencies and facilities covered by the Public Health
Service Personnel Monitoring Program (see Table D-6 for details).
25
-------
Unfortunately, the above choice of major categories, which was
dictated by the nature of exposure data available for this study, does
not provide a clean separation of some types of workers. The govern-
ment category, for example, contains workers that could have been placed
in other categories. First, this category contains both government
employees and employees of private contractors operating government-
owned facilities. Roughly 40% of the workers in this category (primar-
ily DOE and Navy contractor operations) are not government employees.
Second, some workers in this category work in defined occupational
subcategories of other major categories, such as those in dentistry,
veterinary medicine, and industrial radiography. In all, roughly 35%
of workers in the government category work in medical occupations. In
addition, some Federal regulatory and most State and local regulatory
workers are not assessed in this study, as noted in the introduction.
We estimated there were roughly 5 to 10 thousand such workers with mean
doses on the order of 40 mrem. The detailed occupational characteriza-
tion of Federal, State, and local workers in government was not pursued
in this analysis, but is a topic clearly worthy of future study.
B. Assessment of the Number of Workers
Except for the Veterans Administration, Federal agencies provided
comprehensive summary statistical data on the number of persons moni-
tored and their exposures. These data covered not only workers in
government and contractor facilities, but also workers in the nuclear
fuel cycle. We have assumed that these numbers of monitored workers
represent the number of potentially exposed workers in occupations or
facilities where Federal agencies compiled such summaries of exposure
records. Therefore, we did not need to use models to estimate the num-
bers of such workers in 1980, except for workers in the Veterans Admin-
istration, for which complete exposure records or summaries were not
available. The numbers of workers in medicine, industry, and miscella-
neous occupations had to be estimated from various sources of informa-
tion. We summarize our methods for these three categories below.
26
-------
1. Medicine
Workers in medicine were subdivided into those in dentistry, pri-
vate medical practice, hospitals, veterinary medicine, chiropractic
medicine, and podiatry. TO estimate the numbers of these workers we
used the correlation of the number of workers with the number of radia-
tion sources or with the number of professionals within the medical
specialty, as appropriate. Some workers in hospitals may be exposed to
ionizing radiation from both electronic and radionuclide sources. We
have no information on the numbers of such workers or the relative con-
tributions to dose from these sources. Therefore, we avoided the use of
correlations with sources as a primary basis for estimating numbers of
workers in hospitals.
Dental workers comprise the largest subcategory of workers in medi-
cine. Unfortunately, there is no recent study or data base available
for deriving the numbers of various types of dental workers (i.e., den-
tists, dental assistants, and dental hygienists) that are potentially
exposed to radiation. We found that use of data on the number of poten-
ally exposed workers per dental facility (or per x-ray machine) reported
for 1965 (Fe69), which was used in our 1975 report (Co80), leads to an
obvious overestimate of the number of such workers. That is, the calcu-
lated number of potentially exposed workers is greater than the actual
number of such workers. We therefore examined an alternate approach
based on the total number of dental workers. As a result of discussions
with dental professionals we concluded that about 80% of the combined
total of active civilian dentists, dental assistants, and dental hygien-
ists are potentially exposed to radiation. Although this assumption is
somewhat arbitrary, it yields results consistent with earlier estimates,
and we were unable to derive any more exact basis.
Workers in private practice comprised the second largest subcategory
in medicine. We estimated the number of potentially exposed workers,
27
-------
excluding radiologists, Erora the number of x-ray machines in physicians'
offices and in clinics (Fe69). The number of radiologists was taken as
the number of radiologists working in private practice.
Most radiation-related work in hospitals has been supervised by
radiologists (ACR75, PHS73). Therefore, our estimate of potentially
exposed non-Federal hospital workers was based on the number of radio-
logists working in non-Federal hospitals.
Only about 7.5% of all workers potentially exposed to radiation
in medicine work in veterinary medicine, chiropractic medicine, and
podiatry. The number of these workers was estimated from the number
of x-ray machines in each type of practice, except for podiatry, which
I
was estimated from the number of podiatrists.
2. Industry
The industry category includes workers in industrial radiography,
manufacturing and distribution, and in other industrial uses of radia-
tion sources. The numbers of potentially exposed workers in industrial
radiography and in manufacturing and distribution were estimated from
the corresponding numbers of byproduct material licensees of the NRC
and NRC Agreement States. The number of workers in other industrial
uses was estimated from the numbers of byproduct licensees, facilities
using nonmedical x-ray machines, and particle accelerator users. As
noted in the introduction, we have not assessed workers in some mineral
extraction industries that, with few exceptions, are exposed only to
low levels of natural radiation.
3. Miscellaneous Occupations
This category consists of workers potentially exposed in education
and transportation. There are little data and few exposure studies of
these workers upon which to base our estimates.
28
-------
Educational institutions use radiation sources in a variety of
teaching and research situations. Except at relatively few accelera-
tor, irradiator, and reactor engineering facilities, most uses do not
carry a potential for large exposures of workers in a short period of
time. These uses, for example, include most radionuclide tracer stud-
ies. The number of potentially exposed faculty and staff was based on
rough estimates of the number of course offerings to students that
involve the use of radiation.
There are many workers whose exposure is mainly due to handling
and transporting radioactive materials. Since there are no separate
recordkeeping and reporting requirements by government agencies for
such workers, our estimates of the number of workers and their expo-
sures were based largely on KRC studies (NRC77a,77b).
C. Assessment of the Exposure of Workers
The two major sources of occupational exposure information were
data from Federal agencies and commercial dosiraetry data. Federal
exposure data provided nearly complete records of both the numbers of
workers and their exposure. However, these data did not usually contain
information on the age or sex of workers, nor on the number of quarters
worked. Workers reported in Federal data comprise about one-quarter of
the entire potentially exposed work force. These data are summarized
in Appendix D. Our sample of commercial data contained a total number
of exposure records equal to about one-half of the remaining work force.
About half of these data included information on age and sex. To exam-
ine the internal consistency of these data, we compared the mean doses
calculated from all records with those calculated from only those rec-
ords with information on age and sex. For all groups of workers for
which commercial data were used to derive mean doses the agreement was
within 10 rarem. We therefore used age and sex coded data exclusively
to determine all mean doses and dose distributions, to assure internal
consistency for our estimates of dose distributions by age and sex.
29
-------
1. Federal Exposure Data
Table 3 summarizes the results of our analysis of 1980 exposure
data from Federal repositories. No Federal agency provided exposure
data with sex information, and only the Air Force and the Public Health
Service provided age information. Therefore, age and sex distributions
for workers reported herein for the government category were constructed
from the sample of commercial data for government workers.
The NRC reported the largest number of workers. Their exposure
data are summarized annually for four categories of licensees. Exposure
data for workers involved in power reactors and in fuel fabrication and
reprocessing were assigned to the nuclear fuel cycle category, while
that for workers in industrial radiography and in manufacturing and
distribution were assigned to the industry category. Exposure summaries
for workers in the nuclear waste management and uranium mills subcate-
gories were obtained from an NRC special study (Bro83b) updated by more
recent information (Bro83c).
The DOD reported the largest number of workers employed directly
by the government or by government contractors. Within the DOD, the
Navy reported the largest number of workers; this included Nuclear Navy
personnel. Navy and contractor personnel in shipyards (Ri82), and medi-
cal workers. Air Force data included dose distribution summaries for
20 occupational categories and an age profile of workers.
The DOE reported the second largest combined government and govern-
ment contractor work force, and published annual radiation exposure
summaries for ten occupational groups (DOE76-82). We combined the DOE
exposure data for workers in the research and development of fuel fabri-
cation and fuel processing into one group. Exposure data for DOE con-
tractor employees involved in uranium enrichment were assigned to the
nuclear fuel cycle category in Table 4. Exposure data for visitors
(including visiting workers) at DOE facilities are reported in Table 5.
30
-------
Table 3. Summary of 1980 occupational exposure data from Federal agencies
Agency
Number of workers Mean annual dose equivalent*3*
(mrem)
Department of Defense
Navy
Army
Air Force
103,470
64,335
21,050
18,065
61,458
49,483
8.104
3,871
50
80
10
10
90
100
30
40
85,465 40,411
Department of Energy
Reactor Research
Fuel Fab. & Reprocessing
Uranium Enrichment
Weapon Fab. & Testing
General Research
Accelerators
Other
DOE Offices
DOE Visitors(c)
Nuclear Regulatory Commission 160,137 95,551
6,921
5,249
1,871
15,904
36,110
5,315
12,037
2,058
(87,590)
4,267
3,737
1,336
7,245
13,177
1,968
8,167
514
(10,545)
Power Reactors
Fuel Fab. & Reprocessing
Industrial Radiography
Manuf. & Distribution
Other Agencies (d)
PHS<«>
NIH
NASA
NBS
VA(f)
MSHA (Uranium
All Workers
133,712
10,204
11,102
5,119
17,094
5,892
4,154
909
439
5,700
(13,484)
80.635
5,900
6,556
2,460
4,513
614
1,348
194
257
2,100
(7,556)
366.166 201.926
80
170
250
80
40
30
70
130
10
(10)
360
390
100
260
180
20
10
10
20
60
20
(0.5)
130
160
280
350
120
90
100
190
190
40
(60)
600
650
170
430
380
60
80
70
110
90
60
(0.9)
340
(fl)These values were estimated from the data using the hybrid lognormal
distribution model and are rounded to the nearest 10 millirem.
(Wworkers who received a measurable dose in any monitoring period.
fc)These values are not included in the subtotal or the total.
(d)pHS-Public Health Service; NIH-National Institutes of Health; NASA-National
Aeronautics and Space Administration; NBS-National Bureau of Standards;
VA-Veterans Administration; MSHA-Hine Safety and Health Administration.
<«)Workers in the PHS Personnel Honitoring Program (see Table D-6 for details).
(f)The number of workers was estimated from VA data. Dose was estimated from
commercial dosimetry data.
(9)Data is for exposure, measured in working Level Months, to radon decay
products.
31
-------
The Public Health Service of the Department of Health and Human
Services provided exposure summaries of workers for ten occupational
categories (Table D-6b). These summaries also included exposure data
grouped according to five-year age intervals (Table D-6a).
The MSHA summarizes annual exposure of uranium miners to radon
decay products in terms of a specialized unit of exposure - the working
level month (WLM). Since these units are not directly comparable to
the units used to express exposure of other workers (usually reported
in units of rem), radon decay product data are summarized separately.
We also analyzed limited gamma-ray exposure data from MSHA for uranium
miners. In addition, we made crude estimates of mean annual exposure
to radon decay products and mean annual dose from gamma exposure of
nonuranium miners. These analyses are contained in Appendix C and
summarized in Table 5.
The NIH, NASA, and NBS summaries of exposure data provided no
information on the age, sex, or occupations of monitored workers.
2. Commercial Exposure Data
Data from government agencies were insufficient for estimating
exposures in many occupational categories. We therefore obtained
commercial exposure data containing approximately 460,000 records.
These records carried codes that could be identified with the subcate-
gories used in this study (see Table 2), and about 254,000 of these
included the age and sex of the worker. A smaller number of records,
about 21,000, also contained information on dose to extremities. We
examined the mean dose and corresponding dose distributions for all the
records and just those records containing age and sex data, in each code
group, and found significant differences for a few groups. Therefore,
we chose to use only those records having age and sex data to provide
maximum internal consistency in determining the dose, age, and sex
distributions for workers.
32
-------
In spite of the large sample (about one quarter of all workers not
covered by Federal data) the commercial data we used may or may not be
representative. Although most Federal agency data consists of complete
records for well defined groups of workers, this is not usually the case
for commercial data. Further, even though commercial dosimetry services
often maintain permanent exposure records, spurious or questionable rec-
ords may not be investigated and corrected by their customers. However,
our results based on 1980 commercial data are believed to be more reli-
able than our previous results using 1975 commercial data, since they
are based on a larger sample, and high dose records (12+ rems) were
individually confirmed. The fraction of these 1980 data for workers
with me'asurable dose is also consistent with Federal data for 1980; this
was not true for the 1975 data (see Figures B-l and B-2).
D. Analysis of the Exposure Data
In our analysis of exposure data for characteristics such as the
mean dose and shape of the dose distribution, we fitted the data with
the hybrid lognormal (HLN) distribution model (Ku81). This choice was
a result of earlier findings (Ne82) showing the HLN model to have the
following desirable features:
It provides an excellent fit to actual exposure data over the
entire range of observed doses;
It permits characterization of dose distributions using only
three parameters; and
It includes a parameter that reflects the effect of active
control efforts to limit worker exposure.
In this study, the HLN model was particularly useful because: 1) it
provides a useful means for reconstruction of an entire dose distri-
bution from incomplete or coarse-range dose data; 2) it lends itself
33
-------
readily to detailed examination of the consistency and trends of expo-
sure data; 3) it provides a consistent and accurate basis for estimating
collective dose; and 4) it can be used to project dose distributions
satisfying predetermined conditions.
The United Nations Scientific Committee on the Effects of Atomic
Radiation (UNSCEAR82) and the NRC (Bro83a) have noted the improved fit
of the HLN model but used the simpler lognormal distribution model to
fit dose data. However, in most cases we find that the HLN model yields
a better fit and more useful interpretation of dose data (see Appendix F
for further discussion).
1. Dose Distributions
The mean dose, collective dose, and distribution of collective dose
were obtained for each occupational category and subcategory by fitting
the HLN model to the exposure data. Some complete dose distributions
for subcategories of workers were obtained directly from Federal agency
data. The remaining dose distributions were constructed from our esti-
mates of the numbers of potentially exposed workers (Appendix A) and
from commercial exposure data (Appendix B).
Each dose distribution was determined after careful examination of
the input data. First, the validity of the dose data was checked in
several ways. Each dose distribution was compared with similar data
for the same year and/or for other years to examine its consistency and
to identify atypical characteristics. The validity of data containing
exposures above 5 rems, for example, was examined by comparing the good-
ness of fit with the HLN model with and without data above 5 rems (see
Appendix B).
The dose distribution for each of the five major categories of
workers was obtained by summing the dose distributions for their sub-
categories. The dose distribution for all potentially exposed workers
34
-------
in the United States is likewise the sum of the corresponding distri-
butions for the five major categories o£ workers.
The collective dose distribution was determined analytically by
fitting the HLN model to the exposure data and calculating the first
moment distribution (see Appendix B). In the region above 0.5 or 1 rem,
we also estimated the collective dose in each reported dose interval
using a "midpoint" method, in which the number of workers is multiplied
by the midpoint value of dose of that interval. We compared the col-
lective doses calculated for each dose interval from the two methods
and found good agreement, except where there were obviously insuffi-
cient data or large fluctuations in the data. We concluded that the
first moment of the HLN dose distribution provides the best estimate
of collective dose distributions and values for collective dose.
2. Age Distributions
We derived dose and collective dose distributions according to
age, for both males and females, for each of the five major categories
of workers. These distributions were based on the assumption that the
254,000 commercial records coded for both age and sex were representa-
tive. This assumption is supported by the observation that the limited
age data from two Federal agencies (Air Force and PHS) were consistent
with the age distribution for government workers obtained from
commercial data.
The basic characteristics of distributions of all potentially
exposed U.S. workers and their collective dose were further examined
as a function of dose and age. The general results are presented in
Chapter IV. In addition, these analyses were expanded in greater detail
for some worker groups using the HLN distribution model for dose and the
Johnson S distribution for age (Ai57, Jo70). To examine the parameters
of these distribution models for two quite different types of occupation-
ally exposed workers, we selected the subcategories of workers in hospi-
35
-------
tals and nuclear power plants. The results for these expanded analyses
are given in Appendix F.
3. Cumulative Doses
Cumulative dose is defined here as the sum of all prior occupa-
tional doses received by a worker. Figure 2 shows a schematic model
for worker employment in occupations having potential for radiation
EMPLOYMENT
A
ACTIVE
WORKERS
TERMINATION
RE-EMPLOYMENT
TERMINATED
WORKERS
Figure 2. Model of worker employment for estimating cumulative dose.
exposure during a working lifetime. Box "A" represents currently
employed or "active" workers that have potential for radiation exposure.
Box "B" represents workers that have temporarily or permanently termi-
nated such employment. Initial entry to box "A" occurs at first employ-
ment as a potentially exposed worker. Flow of workers from box "A" to
box "B" includes both permanently and temporarily terminated workers.
There is a subgroup of permanently terminated workers in Box "B" who
never again enter Box "A"; only the cumulative doses of these workers
contribute to a lifetime occupational dose distribution.
We made preliminary estimates of mean term of employment, mean
lifetime cumulative dose, and maximum lifetime cumulative dose for four
licensee categories from limited NEC termination data (Bro78,83a,83b).
These data contained records for some workers who do not actually leave
their employer but are recorded as terminated (e.g., some workers who
move from one licensee to another, while in the employ of a contractor
36
-------
to those licensees, are "terminated" as they leave each licensee; these
are reported in NEC termination data, pursuant to 10 CFR Section
20.408). The length of employment determined from this data actually
corresponds to the length of cumulative monitoring periods of workers
for NEC licensees. We also examined limited termination data from DOB
(DOE76-82) and some cumulative dose data from the Navy (Ri82).
Mean'lifetime cumulative dose was examined by correlating the mean
annual increment of the mean cumulative dose to the mean length of
employment of groups of terminated workers. Maximum lifetime cumula-
tive dose was examined by using a trend analysis of lifetime cumulative
doses in descending order of magnitude on a log-log display (Ku80).
These results are described in chapter V. The analysis of mean length
of employment involved fitting termination data with the Johnson S
distribution, the HLN distribution or the lognormal distribution. The
analysis of mean lifetime cumulative dose involved fitting the data with
the HLN distribution model. We discuss these analyses in Appendix F.
37
-------
IV. SUMMARY OF NATIONAL OCCUPATIONAL EXPOSURE FOR 1980
A- Principal Results
The estimated numbers of U.S. workers potentially exposed to
radiation, as well as the number of just those measurably exposed, for
each of five major categories and nineteen subcategories of workers are
listed in Table 4. The estimated mean dose and collective dose for all
workers and for those measurably exposed is also listed for each of
these categories and subcategories.
Our analysis indicates that 1.32 million workers were potentially
exposed to radiation in 1980, and that about half of these received a
measurable dose. The mean dose equivalent to all workers was 110 mrem,
and the dose to those measurably exposed was 230 mrem. The total col-
lective dose equivalent to all workers was 150,000 per son-rents. These
values are compared to those for previous years in Chapter V.
Measurably exposed workers in medicine, industry, the nuclear fuel
cycle, government, and miscellaneous occupations received mean dose
equivalents of 150, 240, 600, 120. and 160 mrera, respectively. These
mean doses to measurably exposed workers were roughly double those to
all potentially exposed workers in each category. Of the various sub-
categories, workers at power reactors, in nuclear waste management, and
in industrial radiography received the highest mean doses. Workers
received very small doses in several subcategories: dentistry, chiro-
practic medicine, podiatry, the Department of Defense, and other Federal
agencies. The three largest contributors to collective dose after power
39
-------
Table 4. Summary of exposure of workers to radiation, 1980
Occupational
category
Medicine
Dentistry
Private Practice
Hospital
Veterinary
Chiropractic
Podiatry
Industry
Radiography
Hanufact. & Oistrib.
Other Users
Nuclear Fuel Cycle'^'
Power Reactors
Fuel Fab. & Reproc.
Uranium Enrichment
Nuclear Waste Mgt.
Uranium Hills
Government
Oept. of Energy'9'
Dept. of Defense
Other Agencies'"'
Miscellaneous
Education
Transportation
All U.S. Workers
Number of workers'3' Mean annual dose'b' Collective dose
(thousands) (c) equivalent (mrem)(c) equivalent'*1'
All Exposed All Exposed (103 person-rem)
584
259
155
126
21
15
8
305
27
29
249
151
133.7
10.2
1.9
0.7
4.8
204
83.6
103.5
17.1
76
26
50
1320
277
82
87
86
12
6
3
156
18
12
126
91
80.6
5.9
1.3
0.4
3.0
105
39.1
61.5
4.5
31
14
17
660
70
20
100
140
60
30
10
120
290
110
110
360
390
100
80
200
160
60
80
50
20
70
60
70
110
150
70
180
200
110
80
30 'e'
240
430
270
210
600
650
170
120
380
260
120
160
90
60
160
no
200
230
41
5.6
16.0
17.2
1.3
0.5
0.1
38
7.8
3.2
26.5
54
52.3
1.1
0.15
0.15
0.8
12
6.3
5.6
0.3
5
1.5
3.5
150
'a'Numbers of workers rounded to the nearest thousand are estimated values.
'b'These values are rounded to the nearest 10 millirem (mrem).
'c'workers who received a measurable dose in any monitoring period.
''"collective doses are rounded to the nearest 1000 person-rems.
'e)Estimated from 1975 data (CoBO).
'''See Table 5 for uranium miners.
'9'Excludes uranium enrichment workers: see the nuclear fuel cycle.
'n)NASA, NBS, NIK, PUS, and VA (see Table 5 for MSHA data for miners).
40
-------
reactor workers (those in other Industrial uses, private medical prac-
tice, and hospitals) exhibited mean measurable doses less than the
average for all measurably exposed workers.
Several groups - underground miners, passenger airplane flight
crews and flight attendants, students, and visitors to DOE facilities -
totaling 0.27 million persons, are not included in our main summary
because their type of exposure is atypical. They are not in permanent
jobs, or their exposure is small and has not been traditionally included
with that of radiation workers (see Table 5 and Appendix C for more
detail). Of these groups, the most significant exposure accrued to
underground miners. We examined the exposure of underground uranium
miners to radon decay products and gamma radiation separately. The
largest exposure of these miners is to the lungs rather than to the
whole body, as is usual for most other workers.
B. The Number of Workers and Collective Dose by Work Category
In Figure 3, the distributions of workers and their collective
dose in the five major categories are illustrated for the year 1980.
Although the largest number of workers are employed in medicine, workers
in the nuclear fuel cycle made the largest contribution to collective
dose. The collective dose for these workers was approximately one-third
of that to all workers; collective doses for workers in medicine and
industry were each about one-fourth that to all workers.
C. pose Distributions
Figure 4 shows the estimated numbers of potentially exposed workers
and collective doses by dose range and sex in 1980. About half of these
workers did not receive a measurable dose; 84% received less than 100
mrem and 94% less than 500 mrera. Less than 0.1% of these workers
received more than 5 rems. We estimate that those workers assigned a
less-than-measurable dose contributed a negligibly small amount, less
41
-------
Table 5. Summary of exposure of some additional groups of individuals
to radiation, 1980
Whole body
radiation
Workers
Uranium miners
Nonuraniurn miners
Flight crews{d)
Flight attendants(e)
Entire Group
Number of persons^ Mean annual dose Collective dose
t \
(thousands) equivalent (mrem)lc> equivalent
All Exposed^ All Exposed^ (103 person-rem)
13.5
4.2
39
58
7.6
2.8
39
58
114.7 107.4
200
150
170
170
170
350
220
170
170
180
2.7
0.6
6.6
9.9
19.8
Others
Students 67
Visitors to DOE facil. 87.6
Entire Group
31
10.5
154.6 41.5
50
10
30
100
60
90
3.3
0.6
3.9
Radon decay
products
Number of persons Mean annual Collective
(thousands) ... exposure (WLMl.. ^exposure
All Exposed1 } All Exposed1 ' (10 person-WLM)
Workers
Uranium miners 13.5 7.6 0.5 0.9
Nonuranium miners 4.2 2.8 0.2 0.3
Entire Group 17.7 10.4 0.4 0.7
6.7
0.8
7.5
(*)Numbers of workers rounded to the nearest thousand are estimated values.
(^Workers who received a measurable dose or exposure in any monitoring period.
(^These values are rounded to the nearest 10 millirem (mrem).
(^Flight crews are estimated to receive a mean incremental dose of 170 mrem from
cosmic radiation; one-half of all flight crew members are estimated to receive
a mean dose of 1 mrem from transportation of radioactive sources.
te^Flight attendants are estimated to receive a mean incremental dose of 170 mrem
from cosmic radiation; one-half of all flight attendants are estimated to re-
ceive a mean dose of 6 mrem from transportation of radioactive sources.
42
-------
NUMBER
OF
WORKERS
COLLECTIVE
DOSE
EQUIVALENT
Figure 3. Distributions of potentially exposed workers and their
collective doses by work category, 1980.
43
-------
700,000 |-
600,000
500,000
g 400,000
ui
o
K
300,000
200,000
100,000
MD-
MD 0.1
m Number of Male Workers
| [ Number of Female Workers
g^$} Collective Dose to Male Workers
^gj^l Collective Dose to Female Workers
MD Measurable Dose
-i 40,000
30,000
0.1- 0.25- 0.5-
jMaJ
PT1
i
I
I
I 3.0- I 4.0-
40
5.0
M
I
5.0-
8.0
m
8.0-
12
20,000
10,000
ui
I
g
ANNUAL DOSE EQUIVALENT (rem)
Figure 4. Potentially exposed workers and their collective
doses by dose range, 1980.
44
-------
than 1%, to the total collective dose (see Table C-3). About 9% of the
collective dose came Erora individual doses less than 100 raillirems and
about 30% from those less than 500 millirems; about 5% was due to
workers receiving more than 5 rems. Thus, about 65% of the collective
dose resulted from workers with doses between 500 and 5000 mrem; these
workers comprised only 5% of all workers. Men outnumbered women for
each dose range except for the lowest range (i.e., those receiving a
less-than-measurable dose). The fractions of all men and all women
workers exposed above 500 mrem were 8% and 2%, respectively. The frac-
tions of total collective doses to men and women receiving more than
500 mrem were about 75% and 40%, respectively.
Figure 5 provides a breakdown for each category of workers of the
results shown in Figure 4. The number of workers or collective dose is
given at the base of each block in this presentation. Each block also
is divided to show the fraction attributed to male and female workers.
About 85% to 90% of workers in each category received less than 100
mrem, except for nuclear fuel cycle workers for whom the fraction was
only 64%. The fraction of workers above 5 rems ranged from zero for
government workers to 0.2% for those in the nuclear fuel cycle. Men
outnumbered women for all dose ranges in each work category except for
doses below 2 rems for workers in medicine and below 1 rem for those in
misce1laneous occupat ions.
The fraction of collective dose above 5 rems was second smallest
(3%) for the nuclear fuel cycle, although this category is the largest
contributor to the 1980 collective dose to all workers. The fraction
of collective dose arising from individual doses above 5 rems was larg-
est (8%) for workers in industry. This is consistent with NRC data for
industrial radiographers (6%) and workers in manufacturing and distri-
bution (11%) (Bro82). Collective doses to men were greater than those
to women for all work categories except at doses below 2 rems in medi-
cine and below 1 rem in miscellaneous occupations.
45
-------
Dose
Equivalent
(rem)
8.0-12.0
5.0-8.0
4.0-5.0
3.0-4.0
2.0-3.0
0-MD
205969 /—7t 108538 / 36028 / S0991 / 23259
306506 / U9U3 / 60037 / 99213 / 44516
1.0-2.0
0.5-1.0
0.25-0.5
0.1-0.25
MD-0.1
A — Medicine
B — Industry
C — Nuclear Fuel Cycle
D — Government
E — Miscellaneous
• - Male
BSS8 — Female
MD — Measurable Dose
A B C D
NUMBER OF WORKERS
E ABODE
COLLECTIVE DOSE EQUIVALENT
(person - rem)
Figure 5. Potentially exposed workers and their collective doses
by dose range and work category, 1980.
-------
The individual and collective dose distributions for all U.S. work-
ers were most closely approximated by those for workers in industry.
The nuclear fuel cycle exhibited distributions distinctively different
from those for all other major categories of workers. These differences
not only reflect the existence of high dose tasks, but also a high level
of effort to control high radiation exposures. This is exhibited by the
presence of high mean doses coupled with a small fraction of workers
exceeding the dose limits.
D. Age Distributions
Distributions of the numbers of potentially exposed workers and
their collective dose by age are shown in Figure 6. These distributions
were developed from the age and sex coded data sample of 254,000 commer-
cial exposure records.
In 1980, the distributions of numbers of male and female workers
and their collective doses by age are quite similar. The largest
fractions (23%) of both workers and collective dose occur in the age
range 25 to 29 years. Workers younger than 20 years of age constitute
only about 2% of the I960 work force and 1% of its collective dose.
Workers older than 65 years account for only 0.6% of the work force and
0.4% of its collective dose. The median age of the work force and the
age at which the collective dose distribution exhibits its median value
are both 31 years.
Women outnumber men in 1980 for ages less than 30 years by about 3
to 2, while above 30 years of age men outnumber women by about 2 to 1.
However, for workers over 20 years old, the fraction of total collective
dose in each age range is larger for males than females. Women younger
than 30 years constitute 58% of the female work force and received 55%
of the collective dose to female workers. Men younger than 30 years
account for 34% of the male work force and received 38% of the collec-
tive dose to male workers.
47
-------
400,000
300,000
in
a
UI
X
oc
o
u. 200,000
O
tc.
ui
oo
100,000
Number of Male Workers
Number of Female Workers
Collective Dose to Male Workers
Collective Dose to Female Workers
18-19 20-24125-29 30-34 I 35-39
40,000
30,000
20,000
10,000
H
ui
ta
O
O
UJ
O
O
AGE (YEAR)
Figure 6. Potentially exposed workers and their collective doses
by age range, 1980.
48
-------
The estimated numbers of workers and their collective doses by age
range in each work category are shown in Figure 7. The largest frac-
tions (20% to 26%) of workers and collective dose are in the 25 to 29
year age range for each category, except for government workers (where
the largest fractions of both workers and collective dose are in the 30
to 34 year age range) and miscellaneous workers (the largest fraction of
workers is in the 20 to 24 year age range).
The fraction of workers younger than 20 years is largest for those
in miscellaneous occupations (7%) and smallest for those in the nuclear
fuel cycle (0.6%). The fraction of workers older than 65 years is also
largest for miscellaneous occupations (2%) and smallest for those in the
nuclear fuel cycle (0.3%). The median ages of male and female workers
combined range from 29 to 33 years for the five work categories: medi-
cine (29 years), industry (32 years), nuclear fuel cycle (33 years),
government (32 years) and miscellaneous (29 years).
Since the distribution of workers by age and the corresponding
distribution of collective dose as a function of worker age are often
different for a given category, the median ages for the two distribu-
tions are generally different. There are also generally differences in
these distributions according to sex. The median ages for the collec-
tive dose distributions for men and women are one year less than the
median ages of these workers in industry (31 years) and the nuclear fuel
cycle (32 years), and one to two years greater than the median ages of
workers in medicine (30 years), government (34 years), and miscellaneous
occupations (30 years).
Female workers in medicine and the nuclear fuel cycle exhibit the
lowest median age (about 28 years) for both number of workers and col-
lective dose age distributions, and, for both number of workers and
collective dose distributions, the highest median age (32 years) occurs
for workers in industry. Male workers exhibit a similar median age
49
-------
Ul
o
60-64
55-59
50-54
45-49
18-19
5636 6633 2487 2634
12619 / 14620 / 6645 / 6242
16805 / 16410 / 9266 / 6618
1564 / 1524 / 2414 / 615
2629Z / Z2729 / 10561 / 13319 / 4193
39SOS / 29032 / 14113 / 1863S
2919 ^mi 4985 / 1630 / 524
64809 / 40136 / 21S21 / 28256 / 1111
103515 /.—. SS612 / 31169 / 51197
149756 / 66011 / 32032 / 4S15S / 13114
I42Z6I / 45444 / 20116 / 26047
8201 / 7642 / BUS / 833
a
4058 / 969
40-44
35-39
30-34
25-29
20-24
A — Medicine
B — Industry
C — Nuclear Fuel Cycle
D — Government
E — Miscellaneous
-Male
- Female
A B C D
NUMBER OF WORKERS
B
COLLECTIVE DOSE EQUIVALENT
(person - rem)
Figure 7. Potentially exposed workers and their collective doses
by age range and work category, 1980.
-------
(about 33 years) in all categories. However, males exhibit a variety of
median ages of exposure for collective dose distributions, ranging from
31 years for those in industry to 35 years for those in government. See
Table B-8 in Appendix B for details.
51
-------
V- REVIEW OF TRENDS IN OCCUPATIONAL EXPOSURE
Substantial Increases in the production and use of sources of
Ionizing radiation have occurred in the United States since the late
1950's. This has led to corresponding increases in the number of poten-
tially and actually exposed workers, as well as in the collective dose
to exposed workers. At the same time, there has been an overall
decrease in the mean annual dose received by workers. Much of this
decrease may reasonably be assumed to be related to changes in
numerical requirements of regulations for radiation protection and to
increased efforts to achieve as low as reasonably achievable (ALARA)
exposures. However, we have not attempted to examine the correlation
of such changes in regulations or increased ALARA efforts with trends
of doses to workers; we simply present the observed trends.
In this chapter we examine trends in occupational exposure of
workers from several perspectives. We first examine workers in the
various occupational groups in terms of their number, mean annual dose,
and collective dose. Next, we examine for these same groups of workers
the distributions of individual and collective doses. Finally, we pro-
ject the observed trends of number, mean annual dose, collective dose,
and individual dose distributions for the period 1960-1980 to the year
1985. We also project the anticipated dose distribution for 1985 under
the constraint of an annual dose limit of 5 rems. Finally, using the
limited data available, we examine the average and maximum accumulation
of dose during an individual's working lifetime. We summarize our
analyses and results below; further details are given in Appendices A
and B.
53
-------
A. Trends in Major Indices o£ Occupational Exposure
1. Number of Potentially Exposed Workers
The numbers of potentially exposed workers in the United States
from 1960 to 1980, with a projection for 1985, are shown in Figure 8.
The number of workers in each occupational category is also indicated.
We have estimated that about 0.50 million workers were potentially
exposed to radiation in 1960; 0.69 million in 1965; 0.78 million in
1970; 1.00 million in 1975; and 1.32 million in 1980 (see Appendix A
for the numerical breakdown by category of workers). This historical
>
trend is approximated by a model which assumes the number of workers
doubles every 14.5 years, starting from one-half million workers in
1960. Such a model yields 0.50 million workers in 1960, 0.63 million
in 1965, 0.81 million in 1970, 1.02 million in 1975, and 1.30 million
in 1980. Our estimates are slightly different from previously reported
values of 0.46 million (K172) and 0.44 million (Co80) in 1960, 0.77
million in 1970 (K172), and 1.1 million in 1975 (Co80). A compendium
of reported summaries of U.S. occupational exposure for 1960, 1970, and
1975 is given in Appendix E.
Our projected estimate of 1.64 million workers for 1985, shown
with dashed boundaries in Figure 8, is based on a detailed examination
of trends in the number of workers and of associated sources of expo-
sure, principally for the period 1975 to 1980. This is in excellent
agreement with the 1.65 million workers predicted by the doubling model.
For perspective, we note that the doubling model corresponds to a mean
annual growth rate of about 5% for potentially exposed workers during a
period when the mean annual growth rates of the entire U.S. labor force
and the U.S. population were 2.0% and 1.2%, respectively.
2. Sources of Occupational Exposure
We estimated the number of potentially exposed workers in the five
major occupational categories by analyzing related indices over a twenty-
54
-------
to
K
UJ
o
K
2
Z
MILLIONS
1.8 -I
1.6-
1.4-
1.2-
1.0-
0.8-
0.6-
0.4-
0.2-
0.0
MISCELLANEOUS
GOVERNMENT
NUCLEAR
FUEL
CYCLE
INDUSTRY
MEDICINE
1960 1965 1970 1975 1980 1985
Figure 8. Estimated number of potentially exposed workers, 1960 to 1985.
55
-------
year period. These relevant indices included numbers of x-ray machines,
radioactive byproduct material licensees, and professionals in related
occupations (see Appendix A).
The trends of numbers of radiation sources in medicine were exam-
ined in terms of the numbers of x-ray machines and byproduct licensees
(shown in Figure 9). Major trends are summarized below; details are
examined in Appendix A. The combined number of medical and dental x-ray
machines has increased by about 58,000 every five years from an initial
value of 218,000 in 1910. Dental x-ray machines have increased more
rapidly than medical x-ray machines. Since 1965, we find that the
number of potentially exposed workers in medicine can be approximated
by multiplying the total number of x-ray machines by the factor 1.8.
The number of medical byproduct licensees of the NRC and Agreement
States increased by about 500 every five years from an initial value of
4,700 in 1970. We find that we can also roughly approximate the number
of workers in medicine by multiplying the number of medical byproduct
licensees by a factor of 100.
In industry we examined the numbers of byproduct material licensees
and registrants of x-ray machines and particle accelerators (Figure 9).
The combined number of licensees and registrants increased by about
3,000 to 4,000 every five years from 11,300 in 1970. The number of
workers in industry can be roughly estimated by multiplying the combined
number of licensees and registrants by the factor 8 in 1965 and increas-
ing the value of this factor by 3 every five years thereafter.
The trends of radiation sources in the nuclear fuel cycle were
examined in terms of the production of enriched U O , the installed
3 8
generating capacity of nuclear power plants, and the mass of spent
fuel (see Figure 9). Production of enriched U 0 rapidly increased
3 8
during the 1950's, but more or less leveled off after 1960 (DOE83).
Installed electrical generating capacity from nuclear power plants
sharply increased in the early 1970's, but the rate of new installed
56
-------
500 i-
Medical
C 1 Dental
NRC
Agreement States
1960
1965
1970
1975
1980
1985
30
O
ujt
II 2°
ui l-
^H
O w
cc 5 10
111 UJ
INDUSTRY
Source Manufacturing
& Distribution
r
Industrial Radiography
Byproduct
Licensees
Other
Industrial
Users
Users of X-ray Machines
& Particle Accelerators
1960
1965
1970
1975
1980
1985
li
•SI
o" =
M ""
3 H
U. Z
I I
O u.
£ O
Mass of Spent Fuel
Installed Generating Capacity
20 -
10 -
- 20
1960 1965 1970
MTIHM - Metric tons initial heavy metal
1975
1980
I
tu
(9
O
uu
Figure 9. Indices related to the numbers of potentially exposed
workers in medicine, industry, and the nuclear fuel
cycle, 1960 to 1985.
57
-------
generating capacity has decreased since 1975 (AIF80, Bro83b, DOE82).
We estimated the 1985 installed generating capacity to be about 70 GWe
from a linear extrapolation of the 1975 to 1980 trend; this is smaller
than estimates reported elsewhere (AIF83, DOE82). The amount of spent
nuclear fuel has steadily increased, as shown in Figure 9 (DOE82).
The large increase in numbers of workers in the nuclear fuel cycle
during the 1970's was due both to the increased number of reactors and
increased volume of maintenance activities. It is difficult to estimate
the number of these workers for 1985 because of uncertainties in recent
trends. However, we can roughly estimate the number of these workers
by multiplying installed generating capacity of nuclear power plants by
about 3 persons per MWe (a value that has been observed since the
mid-1970's).
The trend of types and numbers of radiation sources was not
evaluated for government workers. However, the number of workers
identified here in government (employees of Federal agencies or
government-owned, contractor-operated facilities) has been well
monitored and has been fairly constant at about 0.2 million (within
16%) workers since 1965. This number is about 7% of all Federal
government employees.
The numbers of workers in miscellaneous occupations can be
correlated with the total number of NRC and Agreement State byproduct
material licensees. These licensees have increased by 2,000-3,000
every 5 years from 9,600 in 1965. The associated number of workers
can be roughly estimated by multiplying the number of licensees by a
factor of 3 in 1965 and increasing the value of this factor by 0.5
every 5 years thereafter. The number of workers in education (faculty
and staff) was correlated with the number of academic licensees of the
NRC and the Agreement States. The corresponding number of workers
since 1965 can be roughly estimated by multiplying the number of aca-
demic licensees by a factor of 30.
58
-------
Using the trend analyses described above, our estimates for
numbers of potentially exposed workers in 1985 are: 0.70 million in
medicine, 0.42 million in industry, 0.20 million in the nuclear fuel
cycle, 0.22 million in government, and 0.10 million in miscellaneous
occupations (see Appendix A).
3. Mean and Collective Doses to Workers
The overall trend of occupational exposure was examined in terms
of mean annual dose and collective dose. Figure 10 shows the trend of
mean dose and collective dose to all potentially exposed workers since
1960. The contribution to collective dose is also indicated for each
of the five occupational categories.
Our estimates of mean annual dose showed a decrease from about 180
mrem in 1960 to about 110 mrem in 1980. The mean dose did not change
significantly between 1960 and 1965, but decreased about 30 mrem every
5 years from 1965 to 1975. Since 1975 the decrease has been less rapid;
between 5 and 10 mrera every 5 years.
Our estimate of the mean annual dose for all workers agrees with
the reported estimate of 120 mrem in 1975 (Co80), but not with the
reported estimate of 210 mrem in 1970 (K172) (see Appendix E). The
high value reported for 1970 is attributable primarily to an apparent
over-estimate of the mean annual dose for medical workers (see Appen-
dix B for our analysis).
Our estimate of the U.S. total collective dose shows an increase
from 91,000 person-rems in 1960 to 150,000 person-rems in 1980. The
historical trend can be approximated since 1975 by an increase of about
25,000 person-rems every 5 years, after small fluctuations around
120,000 person-rems between 1965 and 1975.
The projections of mean annual dose and collective dose for 1985
are shown by dotted line and dashed boundaries in Figure 10. These
59
-------
0.20 -
MEAN ANNUAL
E EQUIVALENT
0.00
MISCELLANEOUS
GOVERNMENT
NUCLEAR
FUEL
CYCLE
INDUSTRY
MEDICINE
1960
1965
1970
1975
1980
1985
Figure 10. Mean annual dose and collective dose to potentially
exposed workers, 1960 to 1985.
60
-------
estimates are based on a detailed examination of trends, principally
for the period 1975 to 1980, in the numbers of workers, mean annual
dose, and our analysis of dose distributions.
4. Collective Dose Versus Number of Workers and Mean Annual Dose
We examined the trend of collective dose for the period 1960 to
1985 in terms of its underlying components: the number of workers and
their mean annual dose. Figure 11 shows the trends of collective dose
in each of the five occupational categories and for all U.S. workers
combined. The values shown for five-year intervals, from 1960 to 1985,
are tabulated in Appendices A and B. The diagonal lines are constant
!? fi
collective dose contours from 10 to 10 person-rems.
For medical workers, who exhibited the largest collective doses
before 1980, the trend has been a decrease by about 5,000 person-rems
every 5 years since 1960. This occurs because the decrease of the mean
annual dose (see Figure B-3) has been larger than the increase of the
number of workers (see Figure A-4). Workers in industry exhibit similar
behavior, except that in this case their collective dose has increased
an average of about 7,000 person-rems every 5 years since 1960. This
occurs because the two-fold decrease in mean annual dose has not compen-
sated the much larger increase in the number of workers.
The collective dose for government workers has decreased dramati-
cally, primarily due to the decrease of mean annual dose, but also partly
due to a decrease in the number of workers since 1966. The decrease in
mean annual dose may, in part, reflect the adoption by the Navy (1967)
and the AEC/ERDA/DOE (1974) of a maximum annual dose of 5 rems instead
of the previous 3 rems per quarter. The relatively large increase of
collective dose between 1960 and 1965 was due to a 65% increase in the
number of workers in AEC facilities and a 250% increase in the number
of workers in the Navy, with a simultaneous 270% increase in the mean
annual dose.
61
-------
NUMBER OF WORKERS (103 persons)
Figure 11. Trends in mean annual dose, collective dose, and the number of potentially exposed workers, 1960 to 1985.
-------
In contrast to the decrease of collective dose for medical and
government workers since about 1965, the collective dose for workers
in the nuclear fuel cycle (and in miscellaneous occupations) steadily
increased from 1960 to 1980, due largely to the increased number of
facilities (and therefore workers). This has resulted in the nuclear
fuel cycle becoming the largest contributor to collective dose, in
contrast to being one of the smallest only a decade ago. It is noted
that, in spite of the increasing average age of nuclear facilities and
consequent need for repairs, the mean annual dose to workers in the
nuclear fuel cycle has remained roughly constant over this time period.
The overall trend of the U.S. total collective dose can be charac-
terized as only gradually increasing since 1960. The major contributions
to growth were from government workers (during the period 1960 to 1965)
and from workers in the nuclear fuel cycle and industry after 1975.
Since 1975, increases in contributions from workers in the nuclear fuel
cycle and industry have more than made up for decreases from workers in
medicine and government.
The solid points within each shaded square of Figure 11 represent
our estimates of the numbers of workers, mean annual doses, and collec-
tive doses for 1985. Each point was determined by linear extrapolation
on the log-log plots (Figure 11) of the 1975 to 1980 trends in the num-
bers of workers and mean annual doses. These values were derived as
described in Appendices A and 6. This also provides an estimate of the
collective dose for 1985. The shaded squares show an arbitrary estimated
uncertainty of 20% about the projections of numbers of workers and the
projected mean annual dose. In general, the mean doses predicted by
these simple linear log-log extrapolations provide estimates that are in
good agreement with estimates from our projected dose distributions
obtained by extrapolation of the parameters of the HLN fits to 1975 and
1980 data. For example, the overall U.S. mean dose was 105 mrem from
log-log extrapolation and 110 mrem from the HLN trend analysis; the mean
dose to nuclear fuel cycle workers was 380 mrem from log-log extrapola-
63
-------
tion and 360 rarem from the HLN trend analysis. However, the mean dose
to government workers was 50 mrera from log-log extrapolation and only 30
mrera from the HLN trend analysis. This relatively large difference is a
result of extrapolating the large change in the dose distribution for
government workers between 1975 and 1980 (see Figure B-7).
The 1985 projection of the total U.S. collective dose agrees with
the sura of projections of collective dose for workers in the five cate-
gories, using either the log-log or HLN projections. Similarly, the
projection of collective dose in each category also agrees with the sum
of projections of collective dose in its subcategories using either the
log-log or HLN projections.
B. Trends in Dose Distributions
1. Distributions of Annual Doses to Workers
The trend of doses to highest exposed individuals is one index of
efforts to reduce individual exposures. Figure 12 shows, on a lognormal
probability scale, the annual dose distributions obtained by fitting the
HLN model to the dose distribution data determined in this study for U.S.
workers for the years 1960, 1965, 1970, 1975, 1980, and 1985. (The dose
distributions for 1960, 1965, 1970, and 1985 are not based on comprehen-
sive data, but are shown to provide a chronological perspective for the
more complete 1975 and 1980 distributions.)
There is a constantly increasing curvature of dose distributions in
the dose range above about 1 rera since 1960. The increasing curvature
above 1 rem may be interpreted, according to the HLN model, as a contin-
uing trend of increased effort to limit individual doses. If no atten-
tion is given to reducing doses near the limits, the distribution of
workers on a log probability scale would generally tend to be linear
("lognormal") rather than curved ("hybrid lognormal"). The lognormal
case is approximated by the 1960 distribution and is also observed for
1958 AEC exposure data (FRC60b). This increasing curvature results in
64
-------
w
E
Ul
5
g
ss
on ooooo
99.99999
99.9999
99.999
99.99
99.9
99
95
90
80
70
60
50
40
30
20
1985
10-8
io-7
10-6
io-5
10'
10-2
io-
8
Ul
Ul
Ul
Ul
ui
1 s
a
o
oc
a.
0.01
0.1 1
ANNUAL DOSE EQUIVALENT (rem)
10
Figure 12. Dose distributions for potentially exposed workers,
1960 to 1985.
65
-------
the fraction of workers above 1.5, 5, and 12 rems decreasing by factors
of about 1.1, 2, and 10, respectively, every five years since 1970. At
the same time, the fractions of workers above 0.1 rem and 0.5 rem have
remained almost constant since 1970. Overall, the fraction of workers
above the mean annual dose in any year has been approximately constant
at about 15% since 1960.
Before 1975 the shapes of dose distributions are relatively uncer-
tain below 1 rem, because summaries of exposure data typically contain
no detail in this region, except for an AEC pilot study (ABC68a,68b,
70,71,73). Therefore, we examined all readily available data to recon-
struct likely patterns of doses below 1 rem. From these reconstructions
we estimate that the fraction of all potentially exposed workers that
received less than measurable doses has ranged between 50% and 63% since
1960. From these results, we surmise that the minimum reported dose
roughly decreased from about 20 mrem before 1970 to about 5 mrera in 1980
(see, for example, Figure 12). Although only a simplistic interpretation
of the historical trend of dose distributions, this assumption is consis-
tent with improved dosimeter sensitivity over these years and our recon-
struction of the low dose portions of worker dose distributions.
There are a number of distinct features of the dose distributions
for each of the five major occupational categories. Displays of these
distributions are given in Figures B-4 to B-9 of Appendix B. Overall,
workers in industry most closely parallel the national workforce in 1975,
1980. and 1985.
All workers in government operated under an annual limit of 5 rems
in 1980. We examined this further by fitting the HLN distribution to
exposure data below 2 rems to predict on that basis what fraction of
workers would normally be expected to exceed 5 rems. This procedure
predicted a much larger fraction (0.9%) than that actually observed
(0.05%). We presume that this indicates the effect of increased efforts
to limit doses, especially those to the most highly exposed workers.
66
-------
The fraction of medical workers below 1 rera is similar to that for
government workers. However, as in 1975, there continued to be some
medical workers above 10 rems in 1980, although this fraction has
decreased considerably since 1960. Some of these higher doses may be
due to dosimeters worn outside protective clothing; we have not been
able to evaluate this possibility.
Nuclear fuel cycle workers exhibit a unique dose distribution
compared to other major groups of workers. The fraction (0.2%) of
workers above 5 rems is the largest. (This fraction is smallest for
government workers.) It is perhaps significant that these workers are
regulated under a limit of 3 rems per quarter, rather than 5 rems per
year.
The dose distribution for workers in miscellaneous occupations
was similar to that for medical workers. No interpretive analysis was
attempted for this relatively small and poorly defined group of workers.
We expect the 1985 dose distributions for each group of workers to
reflect the trends discussed above. Thus, the overall dose distribution
of U.S. workers should continue the 1960 to 1980 trend shown in Figure
12. The 1985 dose distribution was estimated by extrapolation of the
trends in the values of the parameters of the HLN model for 1975 and 1980
exposure data. However, since the 1985 dose distribution obtained using
the HLN model exhibits a mean annual dose of 110 mrem, and the previous
estimate of mean annual dose was 105 mrem (see Figure 11), the 1985 dose
distribution (shown in Figure 12) was adjusted slightly to give a mean
annual dose of 105 mrem (i.e., the V" parameter of the HLN model,
detailed in Appendix F, was multiplied by the factor 110/105). This
lognormal probability display of the 1985 distribution shows increased
upward curvature above 0.5 rem, compared to the 1980 dose distribution,
due to a presumed continuing trend of increased efforts to minimize
exposure.
67
-------
2. Distributions of Collective Dose to Workers
The collective dose distributions for U.S. workers are shown in
Figure 13 for the years 1960, 1965, 1970, 1975, 1980, and 1985. These
collective dose distributions were derived analytically from the HLN
fits to the dose distributions shown in Figure 12.
The fraction of collective dose above 1.5 reras decreases from 60%
in 1960 to 34% in 1985, while the fraction of workers above 1.5 reras
remains roughly constant at about 2 to 3%. However, we again observe
a long term trend in the reduction of high doses from the increasing
curvature of the collective dose distributions above 0.5 rem. The con-
tribution to collective dose from doses above 5 and 12 rems decreases
from 15% to 3% and from 2% to 0.001%, respectively, between 1970 and
1985. The estimated decreases in the percent of collective dose above
0.5, 0.75, 1, 1.5, and 2 rems are, very roughly, 3%, 4%, 5%, 6%, and 7%,
respectively, during each five year period between 1975 and 1985. we
observe similar trends for each of the major categories of workers.
3. Projected Dose Distributions in 1985 Under a 5-rem Constraint
The projected 1985 dose distribution for 1.64 million potentially
exposed workers having a mean annual dose of about 105 mrem, i.e., a
collective dose of 175 thousand person-rems, has been presented above.
This distribution contains about 600 workers exceeding 5 rems. Such a
distribution is possible under current Federal Radiation Protection
Guides, which permit doses up to 3 rems per quarter. Here we consider
the possible change in the dose distribution for these same workers at
the same mean annual dose (and therefore also the same collective dose),
but constrained so that essentially no workers are exposed above 5 rems
in a year.
In achieving a reduced dose limit in a given group of workers, one
objective is not to increase the collective dose of that group or any
68
-------
V)
O
Q
O
O
u.
O
H
UJ
o
DC
D
s
U
99.9999
99.999
99*99
99.9
99
95
90
80
70
60
50
40
30
20
10
5
1985
1980
1975
1970
/, 1965
1960 _
0.01
0.1 1
ANNUAL DOSE EQUIVALENT (rem)
10
Figure 13. Collective dose distributions for exposed workers,
1960 to 1985.
69
-------
other group of workers. Given a group of workers projected to receive
a collective dose following some distribution of doses, it is often theo-
retically possible to change the distribution of individual doses without
increasing the collective dose (Ku82c). We examined here, therefore,
dose distributions that have the same collective dose. This, of course,
is an arbitrary case, and, realistically, one would expect the collective
dose to be decreased by a lower upper limit, although under special cir-
cumstances in small groups of workers, the converse is also possible.
We examined dose distributions having a mean dose of 105 rarem for
1.64 million workers, but with the constraint that effectively no workers
exceed 5 rems. This was done by allowing only a miniscule fraction of
all workers to exceed 5 rems; we assumed 1 worker above 5 rems (1 worker
-7
is given by the fraction 6.1x10 of 1.64 million workers). We then
used the HLN model to construct dose distributions having a collective
dose of about 175 thousand person-rems, i.e., a mean dose equivalent of
about 105 mrem. Curve A in Figure 14 shows one of these dose distribu-
tions; it was constrained to have the same fraction of workers with a
less-than-measurable dose (assumed to be 5 mrem) as that of Curve B.
Curve B is our best estimate of the 1985 U.S. dose distribution, as shown
in Figure 12. It was obtained from a linear extrapolation of the 1975 to
i960 trends in the values for the parameters of the HLN model. Curve C
shows the 1980 U.S. dose distribution for comparison.
An interpretation of Curve A relative to Curve B can be made by
noting their point of intersection. This occurs at about 800 mrem, or
at about 97% of the cumulative probability of not exceeding a given dose.
This intersection means that the 3% of Curve B workers above 800 mrem
shift to lower exposures, so that the number of workers above 5 rems
changes from 600 persons to one person. This change results in the
fractions of collective dose above 0.8 rem and 1.5 rems being reduced
from 55% to 42% and 34% to 15%, respectively. Because the collective
dose is constrained to remain 175,000 person-rems, the workers below
800 mrem receive an increased mean exposure. Thus, the fraction of
70
-------
99 .999999
99«9999
K
111
QC
UJ
O
K
J
S
o
99.99
99.9
99
95
90
80
70
60
50
40
30
20
0.01
A — Predicted 1985 Dose Distribution with a 5-rem Constraint
B — Predicted 1985 Dose Distribution without a 5-rem Constraint
C - Estimated 1980 Dose Distribution A
0.1 1
ANNUAL DOSE EQUIVALENT (rem)
10
10-8
10'7
10~6
-5
10
10-3
10
-1
111
_l
<
5
2
|
10-2 g
5
ui
tit
HI
u.
O
to
o
K
a.
Figure 14. Projected dose distribution for potentially exposed
workers for 1985, with and without a 5-rem constraint.
71
-------
collective dose below 800 rarem increases from 45% to 58% while the
fraction of collective dose below 100 mrem only increases about 0.6%.
We believe Curve A provides a realistic estimate of the upper bound of
doses that would result from virtual compliance with a 5 rem limit.
Another perspective on the difference between Curves A and B of
Figure 14 is provided by the number of workers exceeding a specified
dose, as shown in Figure 15. The projected numbers of workers for 1985,
shown as squares and circles in Figure 15, were calculated from the
Curve A and Curve B dose distributions of Figure 14, respectively. The
numbers of workers for other years were calculated from the dose distri-
butions shown in Figure 12.
The number of workers with a dose above 3 rents has decreased since
1965, while the number of workers with a dose above 1 rem has increased
since 1965. Our projected changes in numbers of workers from 1980 to
1985 are shown by either the dashed or dotted lines in Figure 15. The
dashed lines indicate a reasonable expectation of change based on recent
trends (Curve B in Figure 14). On the other hand, we would expect a
significant decrease in the numbers of workers above 2 or 3 rems and the
possibility of an increase in the numbers of workers below 0.75 rem to
achieve the changes, indicated by the dotted lines, that correspond to a
5 rem limit (Curve A in Figure 14). Under our model, the number of
workers receiving greater than 2, 3, 4, and 5 rems would decrease by
factors of 3, 13, 75, and 600, respectively, to achieve a 5 rem limit,
while the number of workers receiving greater than 0.1, 0.25, 0.5 rem
could increase by up to 23%, 27%, and 18%, respectively.
From the above analysis we conclude that achieving the curve A
(Figure 14) distribution of doses in 1985 will require positive super-
visory control and effort, primarily for a few thousands of workers in
industry, the nuclear fuel cycle, and medicine. We note that similar
transitions took place before 1980 among government workers when the
Navy Nuclear Propulsion Program and the Department of Energy adopted
5 rem/y limits in 1967 and 1974, respectively.
72
-------
Ill
5
o
5
LU
LU
s
LU
CO
CC
LU
o
cc
LU
GO
5
z
Measurable Dose A——
00.5
•i:-.!'— °
»0.75
•••••Q i
10
102
10
1985 Prediction in Compliance
with 5-rem Dose Limit
1985 Prediction by Linear
HLN Model
1960
1970
1980
1990
Figure 15. Number of potentially exposed workers exceeding a
given dose, 1960 to 1985.
73
-------
C. Estimated Cumulative Doses
There have been a number of approaches to estimating dose accumu-
lated over the working lifetime of persons occupationally exposed to
radiation (Ja74, UNSCEAR77, Wi77, Co80, AIF81, Ri82). Many of these
approaches involve making assumptions on the length of a working life-
time. In our assessment, we have examined primarily historical data on
cumulative dose to individual workers for which we have not had to make
assumptions concerning the length of a working lifetime.
An analysis of termination data of monitored workers can poten-
tially provide the basis for a characterization of working lifetime
doses. Unfortunately, most termination data contain records for both
permanently and temporarily terminated workers. In addition, it may not
include cumulative doses from different periods of employment and/or dif-
ferent employers. Therefore, the calculation of mean length of employ-
ment and mean cumulative dose from such data will yield smaller values
than those which would be calculated for only permanently retired workers
whose complete employment record is included. We attempted to examine
these effects by comparing the results for different termination periods.
We also analyzed termination data for maximum cumulative doses. This
latter assessment is affected much less than that for mean cumulative
dose by the mixture of temporarily and permanently terminated worker
data.
1. Mean Cumulative Doses
We examined mean cumulative dose to groups of terminated workers
from NRC licensee data (Bro78,83a,83b,83c) and from DOB data (DOB76-82)
by analyzing the trend of mean annual increment of the mean cumulative
dose as a function of the mean term of employment.
Figure 16 shows the trend of mean cumulative dose for several
worker groups with various mean terms of employment and various mean
74
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10
8
U
111
5
UJ
LLJ
DC
U
DOE Termination Data:
E DOE and DOE Contractor Employees
NRC Termination Data:
LU
0.1
P Power Reactor
N Nonpower Reactor (F + I + M)
F Fuel Fabrication and Reprocessing
I Industrial Radiography
M Manufacturing and Distribution
P* Fraction of < 90 day P workers,
made comparable to N workers
Terminating Periods:
A 1969 - 1977
Q 1977 - 1982
V 1975
Q 1980
0.1
1 10
MEAN LENGTH OF EMPLOYMENT (YEAR)
100
Figure 16. Mean cumulative doses for various groups of terminated workers.
-------
annual Increments of mean cumulative dose. The results for most groups
of workers lie near the 1 rem contour of mean cumulative dose and in
general have not moved far from this 1 rem contour during the decade
examined (1969-1980). The termination data for DOE and NRG, except NRC
data for power reactors, yield very similar mean annual increments of
mean cumulative dose and mean term of employment (Figure 16). Our
analyses of Navy data (Sc83) also yielded similar estimates of mean
annual increment (0.22 rem) for a similar mean term of employment (about
5 years). The results for power reactors appear to be displaced below
the 1 rem contour primarily due to a large fraction of short term (i.e.,
less than 90 days) workers. If the high fraction (60%) of power reactor
workers terminated within 90 days is reduced to the fraction (20%) ob-
served for NRC nonpower licensees or DOE, the results for the power
reactor group lie close to a mean cumulative dose of 1 rem (shown by
"P*" In Figure 16). From these results, terminated workers in the
industry, nuclear fuel cycle, and government categories were estimated
to have mean cumulative doses of about 1 rem.
In general, there appears to be only a small increase in mean
cumulative dose with increasing mean term of employment for different
groups of terminated workers. However, our analysis was not able to
separately assess permanently and temporarily terminated workers, nor
were we able to examine the possibility of previous periods of employ-
ment or doses from several different employers. Nevertheless, for the
termination data available, the annual increment of mean cumulative dose
to workers decreases with increasing mean term of employment. Therefore,
we estimate, tentatively, that the mean cumulative occupational dose for
U.S. workers terminated during the period of 1969-1980 is on the order
of one rem.
2. Maximum Cumulative Doses
The trend of the logarithm of maximum cumulative doses, plotted in
descending order versus the logarithm of the numerical ranking of these
76
-------
doses, is shown in Figure 17 for two groups of NEC licensees for the
period 1977 to 1982. One group consisted of power reactor, fuel fabri-
cation, and reprocessing workers; the other group consisted of industrial
radiographers and workers in manufacturing and distribution of byproduct
materials. The first group roughly approximates workers in the nuclear
fuel cycle, while the latter group corresponds to about one-fifth of
workers in industry. The descending trend and slope of cumulative doses
by rank (r) for the 500 terminated workers receiving the highest doses
was remarkably similar for both groups. This trend is proportional to
the reciprocal of the descending order of ranking raised to the 0.3
-0.3
power (i.e., r ). The maximum cumulative dose extrapolated from
the above trend (by fitting the 500 largest doses) is about 110 rents
for both groups. This value is identical to recorded maximum cumula-
tive doses. In view of recent exposure trends, it appears unlikely that
maximum cumulative doses will be larger in the future. Therefore, we
estimate that maximum cumulative doses to U.S. workers in the future
will be no larger than about 100 rents.
We examined NRC termination data to determine whether or not there
was any indication of an overall active effort to limit individual cumu-
lative dose. The mean cumulative dose for workers grouped according
to length of employment generally increased with increasing length of
employment, while the mean annual increment of cumulative dose generally
decreased. Using the HLN model, we found that the inferred degree of
effort to control cumulative dose decreased with length of employment
in each NRC category. Thus, according to present termination data, the
degree of active control appeared greatest in early years of employment,
during the periods of highest mean annual doses. This result is also
consistent with the larger degree of control of exposures inferred for
terminated workers analyzed on a quarterly versus an annual basis. The
above results are also consistent with those terminated workers with
cumulative doses above 25 rents, who had a trend of smaller mean annual
increment of cumulative dose with increasing length of employment. We
77
-------
to3
UJ
I
§
uj 10
3
O
C9
e
x 10"1
UJ
x
10
-2
xr(rem) = 110r
-0.303
• Nuclear Fuel Cycle
(Power Reactors, Fuel Fabrication
and Reprocessing)
D Industry
(Industrial Radiography, Manufacturing
and Distribution)
10
102 103 104
RANKING, r, OF CUMULATIVE DOSE
10s
106
Figure 17. Cumulative doses, in descending order of magnitude,
for terminated employees of NRC licensees, 1977 to 1982.
78
-------
anticipate that cumulative doses will continue to be determined by
efforts to limit annual doses and by the overall tendency of individual
cumulative doses to have smaller mean annual increments for increasing
length of employment.
79
-------
VI. ERROR AND UNCERTAINTY
All of the estimates in our analyses are, inevitably, subject to a
variety of sources of error and uncertainty. Although it was not always
possible to make numerical assessments of error, we have tried to mini-
mize the effects of errors by selecting and modeling the best data avail-
able to achieve the objectives of this study. These objectives were to
summarize as accurately as possible: 1) the number of male and female
workers potentially exposed to ionizing radiation in major occupational
groups in the United States, and 2) the dose and age distributions of
these workers. The methods used to minimize errors and uncertainties
are described below.
A. Introduction
There is no single source of information, such as a Bureau of Labor
Statistics Standard Industrial Classification code, that identifies
potentially exposed workers. We had to rely on our general knowledge to
identify significantly exposed groups of workers. This knowledge has
increased over the years, and we are reasonably confident that all such
groups of workers are now identified, and that this report addresses all
significantly exposed groups. Two exceptions noted in Chapters 1 and 2
are some Federal, State, and local regulatory workers and some workers
in mineral extraction industries. However, doses to these groups are
small.
The available data on the number of workers reflect a wide variety
of reporting practices, especially for workers who are exposed to very
81
-------
low levels of radiation. This variety reflects differences in Federal
and State jurisdictions and responsibilities. In cases where complete
reporting of the number of workers did not occur, we generally examined
two quantities in estimating the number of workers: (1) key indices
related to the size of the work force, and (2) the number of potentially
exposed workers per unit index quantity.
The available exposure data reflect the effects of different levels
of dosimeter performance and different monitoring requirements and prac-
tices. Dosimeter data may include errors and uncertainty related to the
calibration of dosimeters for different radiation energy spectra and for
different exposure geometries (see Appendix C). Monitoring requirements
and practices reflect differences in the purposes for which personnel
monitoring devices are used, e.g., to assure that limits are satisfied,
to provide records demonstrating there is little or no exposure, or to
measure the effectiveness of protective measures. In addition there may
be uncertainty as to whether dosimeters are worn inside or outside pro-
tective clothing, e.g., the objective may be the determination of dose
at the surface of clothing or to the head rather than dose to the whole
body of the worker. Also, the misreading of dosimeters, reporting of
incorrect data by licensees to regulatory agencies, and errors in data
processing can contribute to errors. We did not assess the above sources
of error and uncertainty; we simply identify them and the need for evalu-
ation in future studies.
Personnel monitoring techniques used before 1960 have been discussed
in early documents (NCRP52, Mo67). indications of the level of accuracy
of personnel monitoring devices supplied by commercial dosimetry services
in the early 1960's have been reported for a pilot study (Ua64). Although
we did not assess the effect of errors in the measurement of individual
worker doses, we highlight here some of the results of a recent series
of dosimetry performance tests, which are summarized in Appendix c, on
the assessment of mean doses to large numbers of workers. The results
of these tests show that the absolute value of the mean bias or devia-
82
-------
tion for the determination of whole body dose equivalent was 0.24 for low
energy photons and 0.07 for high energy photons. These tests involved
56 processors, including participants from the military, private indus-
try, national laboratories, nuclear power plants, and commercial pro-
cessors, and incorporate a variety of mixes of the use of film and TLD
dosimeters. For the commercial data that provided the basis for the
majority of our analyses of worker dose in medicine and industry, the
corresponding mean deviations were smaller: 0.01 (film) and 0.09 (TLD)
for low energy photons and 0.04 (film) and 0.01 (TLD) for high energy
photons. This data consisted of approximately 90% film and 10% TLD
records. The uncertainty associated with biases in dose for the commer-
cial data we used is less than the average for all participants in these
performance tests. From these observations we judge that the mean values
of annual dose and collective dose estimated in this study have mean
biases no greater than about 0.2 for most worker groups due to errors in
dosimeter readings.
Our estimates of dose distributions by age and sex were based on
incomplete, but generally substantial samples of dose, age, and sex data
(in most cases, approximately 10-30% of workers). Reliable estimates of
the dependence of dose distributions upon worker age or sex require care-
ful characterization of each worker group in terms of dose, age, and/or
sex information (including historical trend analyses). In a few cases,
this information was available for only a small fraction of the work
force, as, for example, in dentistry (about 3%), and the representative-
ness of the data had to be carefully examined, (see Appendix B for a
discussion of these analyses.)
We examined the data for each worker group for uncertainties and
representativeness. In developing our estimates of dose and age dis-
tributions for all U.S. workers, we examined two basic sources of error
and uncertainty: the estimated probability of workers belonging to spe-
cific dose/age ranges and the weighting factors related to sizes of
worker groups and used to sum the contribution from each subcategory of
workers to obtain aggregate distributions. These are discussed below.
83
-------
B. Methodology
Figure 18 gives a simplified schematic of our basic methodology for
(1) estimating the number of workers, and (2) estimating their dose and
age distributions. The number of individuals and dose/age distribu-
tions for major occupational categories and for all U.S. workers were
obtained as aggregations of occupational subcategories. From these we
calculated mean dose equivalent, collective dose distributions, trend of
the number of workers above specific doses, and other characteristics.
The assumptions and models used for each worker category are given in
Appendices A and B.
C. Number of Workers
The total number of potentially exposed workers in the United
States, N, was calculated as the sum of the number of potentially
exposed workers in five worker categories; N = J K.. The number of
potentially exposed workers in the ith category, N., was computed as
the sum of the number of potentially exposed workers in j subcategories;
N. = 2 N... In turn, we estimated the number of potentially exposed
workers in the jth subcategory of the ith category, N.., from the summed
product of w. . and Z. .. ; N. . = E "i-j^iik' wnere wiiic is tne number of
potentially exposed workers per unit index quantity and Z. . Is the index
quantity for the kth worker group. Thus, the uncertainties and errors
for the determination of N, N., and N. . originate in the estimates
of wljk and Zijk.
In estimating the number of exposed workers, out of all those
potentially exposed, we modeled the available data to assure reliable
and historically consistent results. This modeling Included examination
of the trends in the ratio of actually exposed workers to potentially
exposed workers in each sector of the work force.
To minimize uncertainties In the total number of U.S. workers,
proportionately greater attention was given to minimizing uncertainties
84
-------
OB
Ul
AVAILABLE DATA
AND INFORMATION
SOURCES FOR
WORKER GROUPS
WORK FORCE \
ESTIMATION /
DOSE/AGE \
niCTnlRi iTlftiu \
ESTIMATION /
kTH WORKER GROUP
SELECT AND MODIFY
AVAILABLE DATA
AND ESTIMATE
Zijk AND wijk
SELECT AVAILABLE
DOSE/AGE STATISTICS
AND ESTIMATE
pijk AND cijk
JTH SUBCATEGORY
N.. - 2w--i Z--i
ij ^""ijk^-ijk
k
Frr = N::£cii|rPiik
IJ IJ IJK IJK
iTH CATEGORY
N-- 2N--
IM, ^""i]
Fi*EFn
1
U.S. TOTAL
N - 2N-
i
F=2F;
ESTIMATED AT
EACH LEVEL:
• Number of workers
• Dose/Age Distribution
• Mean Annual Dose
• Collective Dose
• Mean and Median Ages
• Collective Dose Distribution
• Number of Workers Above 5 rems
• Other Characteristics
X • • i 1A/ * • •
^-ijk' wijk
Njj.Nj.N
ijk
— Key indices and numbers of workers per index quantity, respectively,
for the kth worker group of the jth subcategory of the ith category.
— Number of workers in the jth subcategory of the ith category, in the ith category
and in the U.S. total, respectively.
— Estimated probability of workers in dose/age ranges, Pnk, and weighting factor for size of
work force, c-t-,^, for the kth worker group of the jth subcategory of the ith category.
— Dose/age distribution for the jth subcategory of the ith category, for the
ith category and for the U.S. total, respectively.
Figure 18. Schematic of basic methodology for assessing occupational exposure to radiation.
-------
in the larger categories and subcategories of workers. For example.
since medicine is the largest category and dentistry is its largest
subcategory, more effort was given to estimating the numbers of workers
in dentistry than for the smaller subcategories such as podiatry and
chiropractic medicine (see Appendix A).
The selection of data for Z... and w... was generally dependent
upon what indices were most reliable, consistent, and available for the
period 1960 to 1980. For hospital workers, for example, the number of
hospital-based radiologists was used as a key index, rather than the
number ,of hospital x-ray machines, for which no reliable source of data
prior to 1975 was found. The number of potentially exposed workers per
radiologist was estimated with information from an American College of
Radiology manpower study (ACR77), a Public Health service report (PHS83),
and reported numbers of radiologic technologists (PHS79, ARRT80) (see
Appendix A). The numbers of hospital x-ray machines and byproduct
licensees were used as derived indices to examine the correlation with
our estimates of potentially exposed workers in hospitals. Because the
reported number of x-ray machines (HEW65-79; HHS80.82) fluctuated from
year to year, due to the absence of data or uncertainties in the data
from some states, we obtained a more reliable and consistent estimate of
the number of x-ray machines through a lognormal model analysis of the
number of x-ray machines by state and a trend analysis of the number of
x-ray machines for major States (see Appendix A). We minimized the
errors in estimates of N.. for other subcategories by using similar
models for estimating Z... and w.. (see Appendix A).
Federal agencies generally provided reliable data for the number of
monitored workers for each subcategory, N... However, there were uncer-
tainties in some data, and no data before 1970, from several of the small
agencies. To minimize these uncertainties and make estimates where no
data existed, we modeled the trend of N.. for each worker group for
Federal agencies since 1960 (see Appendix A).
86
-------
To examine the reliability and consistency of our estimates of N,
NI( and N.., we compared trends of one group with those for similar
or relevant worker groups at each level of worker aggregation. In addi-
tion, the trends of N and J^ were compared with the trends of the U.S.
population, total labor force, and economic growth (see Appendix A).
Thus, whenever possible at all levels of analysis, we sought to check the
reasonableness and to examine uncertainties in estimated numbers of
workers through examination of trends and intercomparisons with other
suitable indices.
D. Dose/Age Distributions
The dose/age distribution for all U.S. workers potentially exposed
to radiation, F, was calculated as the sum of the dose/age distributions
for the five major categories; F = £ F., Similarly, the dose/age dis-
tribution for workers in the ith category, F., was calculated as the
sum of the dose/age distribution of its j subcategories; F. = J F...
The dose/age distribution for workers in the jth subcategory of the ith
category; F.., was estimated by forming the product of N.. and the
weighted sum of the dose/age distributions for each of k groups of workers
in each subcategory; F..= N.. J ci-ikpi-jir* Tne Wei9ntin9 factors, c^.. ,
were estimated from the relative number of workers, facilities or licens-
ees; and P... is the normalized probability distribution for the kth
ijK
worker group. Thus, the uncertainty and errors for the determination of
F, P., and F.. originate in the estimates of c^, P^- and the previ-
ously discussed N...
As in the estimation of N... we minimized errors in the estimates
of F and F. by giving greater attention to the P.. where most workers
were found. However, available dose/age statistics for P^. vary in
completeness and degree of representativeness. Even statistics from gov-
ernment agencies may be incomplete because of differences in personnel
monitoring programs and reporting requirements. As an example, not all
licensees of NEC are required to report their monitoring data. Our dose
-------
and age data from commercial sources were unavoidably incomplete for any
given category of workers and had unknown degrees of representativeness.
We sought to minimize uncertainties in the P... by giving careful
1JK
consideration to the characteristic shapes of dose and age distributions
for the most important groups of workers by examining the reasonableness
of fit of the data to the HLN and Johnson S_ distributions (see Appen-
B
dices B and F). Similar care was given to estimates of c^^. As an
example, since about 98% of exposed hospital workers are found in uni-
versity and general medical and surgical hospitals, it was important to
determine the number of these hospital workers and their weighting fac-
tors, c... , accurately. We again attempted to minimize such errors
IjK
through the use of trend analyses.
The relation of personnel dosimetry data to actual whole-body dose
to the worker is also uncertain, since 1960, most reported dosimeter
readings are likely to correspond to maximum exposure of the worker due
to careful choice of placement of dosimeters (AEC60, NCRP71, ICRP82).
However, we did not investigate this factor and only summarize and ana-
lyze reported values for personnel dosimetry. Another source of uncer-
tainty in the probability distribution of workers in dose/age ranges,
P... , is differences in personnel monitoring requirements. NEC (ABC60),
OSHA, and States require the monitoring of any individual likely to
receive a dose in any calendar quarter in excess of 25% of 1.25 rems
(i.e., about 300 mrem). Based on our evaluations of monitoring data,
we believe that essentially all workers receiving greater than 300
mrem quarter are monitored. For workers likely to be exposed to less
than 300 mrem/quarter, there are effectively no requirements for
monitoring. Even though the vast majority of monitoring records are
for these workers, and for most installations a policy of monitoring
all potentially exposed workers exists, there remains uncertainty
concerning the real distribution of worker doses below 300 mrem. To
attempt to generate completely verified values for P... over the
ijK
years and among different worker groups, extensive studies would be
88
-------
required. The need for such historical studies has not been assessed.
Despite the above, we believe that the extensive data available for
this study allowed development of reasonably accurate dose and age
distributions, especially for the more highly exposed workers.
Exposure data for workers by age were available only for the years
1975 and 1980. Most of these data are commercial dosimetry data. Dose/
age distributions derived from the commercial data were compared with
some limited dose/age data available from several government agencies
and we found these were quite consistent. We were unable to check the
consistency of dose/age projections for other categories of workers.
E. Conclusions
We have particular confidence in our results for 1975 and 1980.
For these years there was nearly complete reporting for workers in gov-
ernment and in the nuclear fuel cycle and a large sample of commercial
dosimetry data was available for workers in the other major categories.
Our estimates for the years from 1960 to 1970 have greater uncertainty
due to the paucity of available data. For example, the number of
workers in the nuclear fuel cycle was not well reported before 1970.
However, we believe that our estimates of the total number of poten-
tially exposed workers in the United States for this period are useful,
as evidenced by their reasonable correlation with trends in the U.S.
population, U.S. labor force, and other indices (see Figure A-5).
Mean dose, collective dose, and mean dose to measurably exposed
workers were estimated from exposure data fitted to the HLN distribu-
tion model. Mean and median ages were estimated from age data fitted
to the Johnson S_ distribution model. We examined the reliability
D
and characteristics of the fit of data to these probability distribu-
tion models. In most cases, we estimate the error introduced by using
these models to be well within ±5%. There are a few small subgroups of
workers for which the introduced error might be as high as +15%.
89
-------
The collective dose distributions by dose range in each major
category were estimated from the HLN fits of the data for the F.
dose distributions (see Appendix F). This provided a uniform and
consistent method for collective dose evaluations. One source of
uncertainty in calculations of collective dose is the assumption of
some contribution from less-than-measurable exposures. According to
our assessment, however, the estimated contribution of collective dose
from workers assigned less-than-measurable doses was very small, in
most cases less than 1%. Another source of uncertainty derives from
the goodness-of-fit of the HLN distribution model to the data. However,
the observed goodness-of-fit does not lead to significant bias. In most
cases, the values of collective dose to workers belonging to a certain
dose range were estimated to have an uncertainty of about +10%.
90
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100
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APPENDIX A
ESTIMATING THE SIZE OF THE WORK FORCE
-------
CONTENTS
Page
I. INTRODUCTION A-5
II. ESTIMATES OF NUMBERS OF WORKERS IN THE MAJOR WORK
CATEGORIES A-8
A. Medicine A-10
1. Dental Workers A-10
2. Hospital Workers A-14
3. Private Practice A-19
4. Veterinary Medicine, Chiropractic Medicine and
Podiatry A-20
5. Summary of Medical Workers A-24
8. Industry A-25
C. The Nuclear Fuel Cycle A-30
D. Government A-31
E. Miscellaneous Occupations A-34
1. Education A-34
2. Transportation A-38
III. SUMMARY A-40
TABLES
A-l. Estimated number of potentially exposed workers
in dentistry, 1960-1985 A-ll
A-2. Estimated number of potentially exposed workers
in hospitals. 1960-1985 A-16
A-3. Estimated number of potentially exposed workers
in private practice of medicine, 1960-1985 A-21
A-4. Estimated number of potentially exposed workers in veter-
inary, chiropractic and podiatry practices, 1960-1985 . . . A-22
A-5. Estimated number of potentially exposed workers in
medicine, 1960-1985 A-24
A-3
-------
TABLES (Continued)
Page
A-6. Estimated number of potentially exposed workers in
industry, 1960-1985 A-29
A-"7. Estimated number of potentially exposed workers in
the nuclear fuel cycle, 1960-1985 A-31
A-8. Estimated number of potentially exposed workers in
government, 1960-1985 A-32
A-9. Estimated number of potentially exposed faculty and
associated staff in educational institutions, 1980 A-37
A-10. Estimated number of potentially exposed workers in
transportation, 1980 A-39
A-11. Estimated number of potentially exposed workers in
the United States, 1960-1985 A-41
FIGURES
A-l. Estimates of workers and x-ray machines in dentistry,
1960- 1985 A-ll
A-2. Flow chart for estimating the numbers of hospital-based and
office-based radiologists A-15
A-3. Fraction of active nonfederal patient-care (hospital-based
and office-based) and nonpatlent-care radiologists A-15
A-4. Trends of health care costs', health care workers, and x-ray
machines in medicine, U.S., 1960-1985 A-26
A-5. Trends of U.S. population, labor force, gross national
product, and potentially exposed workers, 1960-1985 .... A-42
A-4
-------
APPENDIX A
ESTIMATING THE SIZE OF THE WORK FORCE
I. INTRODUCTION
Many factors influence the determination of the number of workers
potentially exposed to ionizing radiation. The number of such workers
in some professions (e.g., medical radiology and industrial radiography)
is readily available. In other areas, such as industry, education, and
transportation, the number of workers potentially exposed is difficult
to obtain or estimate. Even government data on the number of monitored
workers depend on a number of factors which must be considered when
using the records. Some of these factors are: personnel monitoring
requirements, objectives of monitoring practices, and categorization of
monitored workers. These factors are important because there is no
definition of potentially exposed workers. We have approached this
problem by adopting working definitions of persons potentially exposed
to radiation based on their profession or on monitoring practices. By
examining the trends and characteristics of the numbers of workers
over recent historical periods, we can better understand present distri-
butions of potentially exposed workers in various work sectors and can
reasonably project future distributions. We selected 1960, the year
Federal Radiation Guidance was first promulgated, as the beginning year
for our analysis.
Our numerical estimates of persons potentially exposed to radia-
tion were based, wherever possible, on more than one index to minimize
A-5
-------
uncertainties associated with use of a single index. Then, numerical
estimates from several indices were compared and basic assumptions for
each method examined and adjusted until consistency was reached among
them. Finally, as a test of the reasonableness of our estimates, we
compared trends in the number of potentially exposed workers with trends
in other indices, such as relevant economic indicators or the size of
the U.S. work force.
Our procedure for estimating the number of potentially exposed
persons in a specified group of workers was to:
«
1) Examine and select one or more indices (i.e., number of
* licensees, x-ray machines, or professional workers) for
estimating the number of workers over a specified period
of time;
2) Model the data for each index to determine the most
consistent data for the relevant time period;
3) Model the number of workers per unit index quantity;
4) Estimate the number of workers for each index for the
specific time period from the results of steps 2 and 3;
and,
5) Compare estimates of the number of workers from each
selected index. Where there was more than one relevant
index, the procedure was to return to step 3 and itera-
tive ly examine and adjust model parameters or assumptions
until satisfactory agreement of numerical estimates was
obtained.
This procedure assured intercomparability of estimates over a period of
years as well as the most consistent estimates for any year.
A-6
-------
To illustrate the above procedure, we consider its application to
estimating the number of potentially exposed workers in medicine. At
step 1, we selected some input data, e.g., the reported numbei^ of x-ray
machines, radioactive byproduct material licensees, or professionals in
an occupational subcategory. The data for each index are not always
complete or accurate. An example of incomplete data is the reported
number of x-ray machines (HEW65-79, HHS80, 82). These annually reported
data have not always included every State, the District of Columbia, and
Puerto Rico, and some data consists of estimates, rather than accurate
counts of registered machines.
At step 2, we modeled the data for each index. As an example, this
was done for medical x-ray machines by first modeling and adjusting the
reported data according to (1) the historical trend of the number of
x-ray machines in each State and (2) the lognormal distribution of the
number of x-ray machines by State. (This procedure was suggested by
our statistical analysis, which showed that the number of x-ray machines
were distributed lognormally among the states and that the total number
BV-
of x-ray machines had a simple historical trend for the period 1965
through 1980.) Then, in a similar fashion, the number of x-ray machines
for each subcategory of medicine was obtained from analysis of histori-
cal trends.
We next (step 3) determined the number of potentially exposed
workers per unit index quantity. This, for example, was the number of
potentially exposed workers per x-ray machine, per byproduct licensee,
or per "professional" worker (e.g., radiologist). In step 4, we calcu-
lated the number of workers from the product of the index quantity and
the number of workers per unit index quantity. At step 5, we cross-
checked the estimated number of workers with the results of the other
relevant indices or alternative approaches. The procedure was then
iteratively repeated at step 3 until agreement was reached among the
different approaches.
A-7
-------
We indicate below, for each group of workers, the basic indices
used to calculate the number of workers. We designate as derived
indices the quantities checked for correlation with the results calcu-
lated from the basic indices.
It. ESTIMATES OP NUMBERS OP WORKERS IN THE MAJOR WORK CATEGORIES
We estimated the number of potentially exposed workers in the five
categories and nineteen subcategories listed in Table 2. The numbers of
these workers were estimated in each subcategory and category according
to the methodology shown in Figure 18. We sought to obtain accurate
estimates of the number of all types of workers, but especially for the
largest groups. Since medical workers are the most numerous, we gave
particular attention to these workers and to dental workers, their
largest component.
in our 1975 report (Co80), the results of a study by Fess (Fe69),
which related the number of potentially exposed workers to the number
of medical x-ray machines, were used to estimate the number of poten-
tially exposed workers in medicine. However, because the Fess study
was based on 1965 data, we reexamined the validity of using this method
and results for the entire period 1960-1985. We concluded that this
approach was useful for estimating the number of workers in private
practice (except radiology), veterinary medicine, and chiropractic medi-
cine. However, for dentistry, hospital, and podiatric workers we used
professional manpower data (PHS73b,75,76.79,82; DOE75,80,81; ACR75,
77,80; ARRT80), because the Fess method did not yield reasonable
results. Since we had little direct data on the number of potentially
exposed medical workers, we compared the trends of projected numbers of
various potentially exposed medical workers to corresponding types of
medical doctors and allied medical personnel.
Potentially exposed workers in industry comprised the second
largest group of workers in 1980. The lack of detailed information
A-8
-------
precluded our generating estimates for many of the specific types of
Industrial occupations, such as well-logging, nondestructive testing,
and radiopharmaceutical production. Therefore, we used the same three
broad subcategories used in the 1975 study. We also relied heavily on
trend analysis to assure consistent estimates for these workers over
the period 1960 to 1980. Since this group of workers is projected to
have the second largest collective dose in 1985, more detailed informa-
tion is desirable for future summaries of national occupational
exposure.
The number of workers in the nuclear fuel cycle was the second
smallest among the five major categories of workers for the period
1960-1980. All data were obtained from the NRG and DOE, under the
assumption that the number of potentially exposed workers was identical
to the number of monitored workers. However, for the period before
1970 we used a trend analysis similar to that used for workers in
industry to estimate the fraction of workers that should be assigned to
each subcategory.
The number of potentially exposed workers in government has
remained intermediate in size among the major categories of workers
for the period 1960-1980. Due to the existence of relatively consis-
tent and comprehensive recordkeeplng practices, we believe that nearly
complete data were obtained from Federal agencies. Some additional
trend analysis was needed to estimate the numbers of some workers
before 1970.
The number of workers in miscellaneous occupations amounted to
less than 6% of all potentially exposed workers in the United States.
To estimate the number of these workers, we used a method similar to
that used in our 1975 report and checked the results against the trends
for byproduct licensees and workers exposed to other sources of radia-
tion.
A-9
-------
A. Medicine
The specific method used to estimate the number of potentially
exposed workers Cor each subcategory of medicine is described below.
1. Dental Workers
Table A-l shows our estimates for the number of potentially exposed
dental workers. We relied heavily on numbers of professional dental
workers and correlated our estimates of potentially exposed workers with
two indices: the number of dentists and number of x-ray machines. The
data for the number of active civilian dentists is believed to be more
reliable than that for the number of dental x-ray machines.
The number of potentially exposed dental workers lies somewhere
between the total number of active dentists, as a lower estimate, and
the total number of workers in the dental work force, as an upper esti-
mate (see Figure A-l). The latter includes dentists, dental assistants,
and dental hygienists. Many dentists have more than one x-ray machine
and may have dental assistants and dental hygienists assisting them in
or doing all dental radiography. From these considerations and exami-
nation of the number of potentially exposed workers per dentist and per
x-ray machine (Fe69), we concluded that the number of potentially
exposed dental workers for the period I960 to 1980 was most simply
expressed as 80% of the sum of active civilian dentists, dental assist-
ants, and dental hygienists. The detailed modeling and considerations
leading to this conclusion are summarized below.
a. Number of Potentially Exposed Workers per Dentist
Dental workers as a group are potentially exposed, but not all such
workers are involved in dental x-ray procedures. The number of dentists
practicing in offices is about 90% of active civilian dentists (PHS82).
A-10
-------
Table A-1. Estimated number of potentially exposed workers in dentistry, 1960-1985
Workers (103)
Derived Indices
Dentists*) (lo3)
Workers/Dentist
(c) 3
X-ray Machines (10 )
Workers/Machine
1960
134
85
(1.58)
81
(1.65)
1965
150
90
(1.67)
94
(1.60)
1970
177
96
(1.84)
107
(1.65)
1975
215
107
(2.01)
149
(1.44)
1980
259
121
(2.14)
191
(1.36)
1985
304
135
(2.25)
233
(1.30)
(^Workers potentially exposed to radiation from the operation of dental x-ray
machines.
ttOActive civilian dentists; number obtained from PHS82, except for 1985 estimate.
fc)Adjusted or extrapolated 1985 number from lognormal analysis of reported data
(HEW65-79; HH580.82).
THOUSANDS
400
300 •
1960
1970
1980
Figure A-1. Estimates of workers and x-ray machines
in dentistry, 1960-1985.
A-ll
-------
We assumed that about 90% of dentists practicing in offices were poten-
tially exposed; this is approximately equivalent to 80% of all active
civilian dentists. We estimated that about 85% of all currently li-
censed dental assistants and dental hygienists were actively practic-
ing, based on Public Health Service data (PHS82). We assumed that about
90% of practicing dental assistants and dental hygienists were poten-
tially exposed. That is close to 80% of all dental assistants and den-
tal hygienists. We did not consider laboratory technicians or clerical
staff, even though they may be exposed or monitored in some dental
offices. From these considerations and simultaneous comparisons with
projections based on the number of x-ray machines, we approximated
potentially exposed dental workers as 80% of active civilian dentists,
dental assistants, and dental hygienists. From this result, the derived
index for the number of workers per dentist was calculated and is given
in Table A-l.
The number of active civilian dentists increased by 13% and 26% for
the periods 1960-1970 and 1970-1980. respectively (PHS82). The number
of active civilian dentists per 10 civilian population was nearly
constant at about 47 from 1960 to 1970, but increased gradually to 53
by 1980 (PHS82). We projected the number of active civilian dentists
for 1985 to be 135,000 (58 dentists per 10 civilian population)
from the 1975-1980 trend. The numbers of dental assistants and dental
hygienists were estimated from "Health Resources Statistics" before
1977 (PHS73b, 75,76,79), and from "Health Manpower Projections" (PHS81)
and other information (We83) after 1977- Dental workers employed by
the Department of Defense and the Veterans Administration are included
in those subcategories, rather than in the dentistry subcategory of
medical workers.
b. Number of Potentially Exposed Workers per X-ray Machine
Using the number of potentially exposed dental workers per dental
x-ray machine derived from a study by Fess (Fe69), the number of poten-
A-12
-------
tially exposed workers in 1965 and 1975 is projected as about 91% and
100%, respectively, of the total number of all active and inactive den-
tal professionals, since these estimates were greater than the number
of active dental workers, a more realistic approach was sought. By
comparing the number of workers per dentist with the number of workers
per x-ray machine, we concluded that about 80% of active civilian den-
tists, dental assistants, and dental hygienists are potentially exposed.
This corresponds to a value of 1.65 workers per x-ray machine in 1960
(Table A-l). The number of workers per dental x-ray machine was roughly
stable at about 1.65 until 1970 and then decreased gradually to a pro-
jected value of 1.3 in 1985. These results are consistent with numbers
of persons found operating x-ray machines in contemporary dental offices
having more than one machine (Cr84, Bo84, Brn84). Table A-l summarizes
these results for the period 1960 to 1985.
The total number of dental x-ray machines reported by HEW/HHS
(HEW65-79; HHS80.82) has fluctuated from year to year, because not every
State reported each year. These fluctuations are shown in Figure A-l
by curve "F." However, by adjusting the total number of dental x-ray
machines (excluding Federal machines) according to a lognormal analysis
of ail dental x-ray machines by States and the historical trend for
each major state, we obtained the simple trend given by curve "B." We
believe that this adjusted number of dental x-ray machines also provides
a reasonable index for estimating the number of potentially exposed den-
tal workers.
c. Dental Summary
Figure A-l shows the overall growth in the numbers of dentists,
x-ray machines, and dental work force for the period 1960-1985. The
number of potentially exposed workers estimated by Fess (Fe69) for 1965
lies between Curve D, all practicing dental workers, and Curve E, all
dental workers. The 1975 number of potentially exposed dental workers
A-13
-------
used in our previous report (Co80) is also close to Curve E. Both of
these values appear to be unrealistically high. We concluded that the
number of dental workers potentially exposed to radiation is reasonably
approximated by curve C.
2. Hospital Workers
We used the number of radiologists as the basic index to estimate
the number of potentially exposed workers in hospitals. We then used
these estimated numbers of workers to examine their correlation with
numbers of x-ray machines and numbers of byproduct licensees. These
two correlations served as derived indices.
a. Number of Potentially Exposed Workers per Radiologist - Basic
Index
Since the early 1960's most radiation-related work in hospitals has
been done under the supervision of radiologists (ACR75, PHS73a). There-
fore, the number of radiologists was selected as the basic index for
estimating the number of potentially exposed workers in this subcate-
gory. However, we first had to determine the number of radiologists
working in hospitals. Figure A-2 shows our method for estimating the
number of hospital-based and office-based radiologists in the non-
federal (civilian) sector.
The percentage of active radiologists (ACR77, ACR82) out of all
physicians (PHS82) increased from 2.5% in 1960 to 4% in 1970. It
increased much less between 1970 and 1980; and we project 4.3% in
1985. This growth corresponded to the number of active nonfederal
radiologists increasing from 5,800 in 1960 (3.3 radiologists per 10
civilian population) to 18,800 in 1980 (8.3 radiologists per 10
civilian population). The percentage of active nonfederal radiologists
has been essentially constant at about 91% (PHS73b,75,76,79). We
A-14
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NUMBER OF
RADIOLOGISTS
REPORTED BY ACR
\
INCLUDING RESIDENT RADIOLOGISTS
NUMBER OF
ACTIVE
RADIOLOGISTS
\
NUMB
ACTIVE NO
RADIOL
1
ABOUT 91%
t
EROF
NFEDERAL
OGISTS
ABOUT 6%
r
NUMBER OF
NONPATIENTCARE
RADIOLOGISTS
ABOUT 94% NUMBER OF
RADIOLOGISTS
SEE FIGURE A-3 ^S -^^ S
NUMBER OF NL
HOSPITAL- BASED OFF
RADIOLOGISTS RA[
SEE FIGURE A-3
NUMBER OF
OFFICE-BASED
RADIOLOGISTS
EFFECTIVE
NUMBER OF
HOSPITAL-BASED
RADIOLOGISTS
EFFECTIVE
NUMBER OF
OFFICE-BASED
RADIOLOGISTS
Figure A-2. Flow chart for estimating the numbers
of hospital-based and office-based radiologists.
100
1960
Nonpatient Care -
1965
1970
1975
1980
• • - (DOC 75, 80, 81)
DO - (PHS73b, 78, 76,79)
1985
Figure A-3. Fraction of active nonfederal patient-care
(hospital-based and office-based) and nonpatient-care radiologists.
A-15
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Table A-2. Estimated number of potentially exposed workers in hospitals, 1960-1985
1960 1965 1970 1975 1980 1985
Workers (103) 30 48 70 96 126 162
Basic Index
Radiologists'' (10 1 .
Workers/Radiol ogi st W
Derived Indices
(r) 3
X-ray Machines '(10 )
Worker s/Machinew>
Licensees(e)(103)
Workers/Licensee^^
A.6
(6.2)
32
(0.94)
1.1
(26)
6.9
(7.0)
34
(1.41)
1.7
(28)
9.1
(7.7)
36
(1.94)
2.3
(30)
11.3
(8.5)
46
(2.09)
3.2
(30)
13.7
(9.2)
56
(2.25)
4.3
(29)
16.2
(10)
67
(2.42)
5.5
(29)
^Effective number of nonfederal radiologists in hospitals (see Figure A-2). Basic
data from ACR82.
(b)Estimated or extrapolated from ACR75 and PH583.
(c)Estimated or extrapolated from lognormal analysis of data (HEW66-79; HHS80-82, Fe69).
^'The number of workers per machine or byproduct licensee was calculated from number of
x-ray machines or licensees and the number of workers obtained from basic index approach.
{e)Estimated or extrapolated from NRC65-82.
project the number of active nonfederal radiologists to be 23,400 in
1985 based on the observed increase between 1975 and 1980.
The number of potentially exposed workers per active nonfederal
radiologist was estimated using information from an American College
of Radiology (ACR) manpower study (ACR77), "Statistics on Hospital Per-
sonnel" (PHS83), and the reported number of radiologic technologists
(PHS79, ARRT80). We assumed that the number of workers per radiologist
was the same in private practice and in hospitals.
The fraction of radiologists in patient and nonpatient-care out of
all active nonfederal radiologists was assumed to be about 94% and 6%,
A-16
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respectively, from 1960 through 1985 (DOC75,80,81; PHS73b,75,76,79).
The fraction of all radiologists active in patient care in hospitals
was estimated from an ACR manpower study (ACR75), "Health Resources
Statistics" (PHS73b,75,76,79), and other information (DOC75,80,81).
The resulting distribution of these radiologists from 1960 through 1985
is shown in Figure A-3. Many radiologists work in more than one office
and/or hospital (ACR75,77,82). According to a recent study, 80% of
office-based radiologists reported serving in hospitals 75% of their
time (ACR82). Therefore, we estimated 60% of office-based radiologists
were effectively full-time hospital-based radiologists. From these
considerations we define the effective number of office-based radiolo-
gists as 40% of the number of office-based radiologists and define the
effective number of hospital-based radiologists as the sum of the num-
bers of all nonpatient care radiologists, all hospital-based radiolo-
gists, and 60% of the number of office-based radiologists (see Figure
A-2).
We estimated the number of potentially exposed workers in hospitals
from the effective number of hospital-based radiologists and the number
of workers per radiologist. The number of workers (126,000) shown in
Table A-2 is consistent with the number of hospital personnel (full-
and part-time) in radiological services (99,000) reported for U.S.
registered hospitals in 1980 (PHS83). From this we conclude that our
model for calculation of effective numbers of hospital-based and office-
based radiologists is reasonable.
b. Number of Potentially Exposed Workers Per X-ray Machine
and Per Licensee - Derived Indices
We examined the correlation of the number of hospital x-ray machines
reported by HEW/HHS (HEW65-79; HHS80.82) with the number of potentially
exposed workers. Again, the number of machines fluctuated, because not
all States were included each year. However, by modeling the number of
x-ray machines (as we previously described for dental x-ray machines),
A-17
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we obtained the 1960-1985 trend shown in Table A-2. The number of hos-
pital x-ray machines before 1971 was estimated from the total number of
medical x-ray machines multiplied by the (back-extrapolated) ratio of
hospital machines to the total number of medical machines. From the
number of x-ray machines and the previously determined number of workers
in hospitals, the number of workers per x-ray machine was estimated.
We also examined the correlation of the number of hospital workers
with the number of byproduct material licensees. The growth in the
number of NRC and Agreement State byproduct licensees in hospitals was
relatively uniform except for 1976. From the number of licensees and
the previously determined number of hospital workers, the number of
potentially exposed workers per hospital byproduct licensee was derived
and found to have been virtually constant at about 30 since 1970 (see
Table A-2). This value is slightly larger than the number of monitored
persons per licensee in the "medical institutional-other" category
reported by NRC (Co78; Bro81,82): 29 in 1975, 22 in 1978, 26 in 1979.
This would be expected since those workers associated only with x-ray
machines need not be reported by licensees to the NRC.
Our trend analyses of numbers of x-ray machines, byproduct material
licenses, and professional workers for the period 1960-1985 permitted
us to examine the correlation with the number of potentially exposed
workers. The increase in number of therapeutic and diagnostic x-ray
machines (HEW65-79; HHS80.82) in the hospital subcategory was 56% for
the period 1970-1980; we estimated it to be about 46% for the period
1975-1985. The growth in number of radioactive byproduct licensees
(NRC65-82) for hospitals was 87% for the period 1970-1980; we estimated
it to be about 70% for the period 1975-1985. The corresponding growth
in the number of potentially exposed workers was estimated to be about
80% for the period of 1970-1980, and about 70% for the period 1975-1985.
From these results, we concluded that the best derived index is the num-
ber of byproduct licensees. This correlation of number of workers with
number of licensees appears to offer an alternative approach for future
studies.
A-18
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3. Private Practice
The number of potentially exposed workers in private practice is
made up of the sum of workers for office-based physicians and radiol-
ogists. The number of workers associated with radiologists was des-
cribed earlier. The number of workers associated with physicians was
estimated from the number of physician x-ray machines and previous
estimates of the number of workers per machine (Fe69).
a. Office-Based Practitioners
The number of active nonfederal office-based physicians increased
slowly from 181,000 in 1960 to 189,000 in 1970. However, the number
increased sharply thereafter from 204,000 (96 physicians per 10
civilian population) in 1974 by an annual average increment of about
9000 (PHS82, DOC81). From this, we projected the number of office-
based physicians for 1985 to be 300,000 (129 physicians per 10
civilian population).
i. Nonradiologists
The number of potentially exposed workers associated with office-
based physicians (except radiologists) was estimated from the number of
physician x-ray machines (including those designated by HHS for clinics,
x-ray vans, and others, but excluding those in private radiology prac-
tice (HHS82)) and the number of workers per x-ray machine. For lack of
a better estimate, we have used the value of 2.24 workers per machine
derived from Fess's 1965 data (Fe69) and assumed it to be roughly con-
stant over the entire period 1960-1985. Because the reported number of
physician x-ray machines (HEW65-79, HHS80.82) had large annual fluctua-
tions, we adjusted them as previously described for the dental and
hospital subcategories. The number of machines increased very slowly
from 47,000 in 1960 to 48,000 in 1980 and was estimated to remain about
48,000 in 1985. Thus, the associated number of potentially exposed
A-19
-------
workers was calculated to be slowly increasing from about 105,000 in
1960 to an estimated 108,000 in 1985.
ii. Radiologists
The number of potentially exposed workers associated with office-
based radiologists was estimated from the number of office-based radiol-
ogists (see Figure A-2) and the estimated number of workers per radiolo-
gist (described in hospital subcategory). The increasing specialization
(among other changes) in medicine has caused the number of potentially
exposed radiology workers to increase by factors of about 3 and 2.5 in
the periods 1960-70 and 1970-80, respectively. The estimated numbers
of radiology workers are given in Table A-3.
The total number of potentially exposed workers in private practice
is the sum of nonradiology workers estimated for office-based physicians
and radiology workers estimated for office-based radiologists. This
result is shown in the first row of Table A-3.
b. Private Practice - Derived Indices
We also examined the correlation of the number of potentially
exposed workers in private practice offices with the number of physi-
cians in private practice, the number of x-ray machines, and the number
of byproduct licensees. The derived correlations for these indices are
shown in Table A-3. The number of workers per physician in private
practice shows the most stable and consistent correlation.
4. Veterinary Medicine, Chiropractic Medicine, and Podiatry
The numbers of potentially exposed workers in veterinary and
chiropractic medicine were estimated using x-ray machines as the basic
index. For podiatry, we used the number of podiatrists.
A-20
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Table A-3. Estimated number of potentially exposed workers
in private practice of medicine, 1960-1985
Workers (103)
Nonradiology workers (103)
Radiology workers (103)
Derived Indices
Physicians (a)(103)
Workers/Physi ci an
X-ray Machines (b)(103)
Workers/Machine
(r\ 3
Licensees^dO )
Workers/Licensee
1960
111
105
6
181
(0.61)
49
(2.26)
1.3
(85)
1965
116
105
11
185
(0.63)
52
(2.23)
1.8
(64)
1970
123
106
18
189
(0.65)
55
(2.24)
2.3
(53)
1975
136
107
29
213
(0.64)
56
(2.43)
2.1
(65)
1980
155
108
47
258
(0.60)
57
(2.72)
1.5
(103)
1985
180
108
72
300
(0.60)
58
(3.10)
0.9
(200)
^Active nonfederal private office physicians, estimated from OOC81.
tb)X-ray machines in physicians' (including radiologists') offices, clinics, x-ray
vans, and others. Values were estimated from HEW65-79 and HHS80.82
after adjustment using lognormal analysis.
(c)Estimated from NRC65-82.
a. Veterinary Medicine
The number of veterinarians increased by about 30% for the period
1960-1970 and 40% during the period 1970-1980 (PHS82). The number of
veterinarians in 1985 was estimated from the 1975-1980 trend to be
42,800. The number of veterinary x-ray machines estimated from HEW/HHS
reports (HEW65-79, HHS80.82) increased by about 20% and 70% for the
periods 1960-1970 and 1970-1980, respectively. The number of x-ray
machines in 1985 was estimated from the 1970-1980 trend to be 12,200.
We estimated the number of workers by using the value 2.12 workers per
veterinary x-ray machine (Table A-4) obtained from the Fess study
(Fe69).
A-21
-------
Table A-4. Estimated number of potentially exposed workers
in veterinary, chiropractic and podiatry practices, 1960-1985
Occupation
Veterinary Medicine^3'
workers (103)
Basic index
X-ray Machines (103)
Workers/Machine^
Derived Index
Veterinarians (103)
Workers/Veterinarian
1960
)
11
5
(2.12)
20.6
(0.53)
1965
12
5.5
(2.12)
23.3
(0.52)
1970
13
6
(2.12)
25.9
(0.50)
1975
17
8.1
(2.12)
31.1
(0.55)
1980
21
10.1
(2.12)
36.0
(0.58)
1985
26
12.2
(2.12)
42.8
(0.61)
Chiropractic Medicine (a)
Workers (103)
Basic Index
X-ray Machines (103)
Workers/Machine^
Derived Index
Chiropractors (103)
Workers/Chiropractor
Podiatry (a>
Workers (103)
Basic Index
Podiatrists (103)
Workers/Podiatrist
Derived Index
X-ray Machines (103)
Workers/Machine
11
9.3
(1.18)
14.3
(0.77)
5
6.7
(0.8)
3.8
(1.5)
12
9.9
(1.18)
15.5
(0.77)
6
7.1
(0.8)
4.3
(1.5)
14
11.5
(1.18)
17.9
(0.77)
7
7.3
(0.9)
4.7
(1.4)
15
13.1
(1.18)
20.3
(0.75)
8
8.9
(0.9)
5.9
(1.4)
17
14.7
(1.18)
22.7
(0-75)
10
10.8
(0.9)
7.1
(1.4)
(a*Number of doctors estimated from PHS73b; PHS75,76,79,82.
(b)Fess study (Fe69).
estimate based on trend analysis.
A-22
-------
b. Chiropractic Medicine
The number of chiropractors estimated from PHS reports (PHS73b,75,
76,79) increased by about 10% and 30% for the periods 1960-1970 and
1970-1980, respectively. The number of chiropractors was estimated
from the 1970-1980 trend to be 22,700 in 1985. The number of chiro-
practic x-ray machines was estimated from HEW/HHS reports (HEW65-78,
HHS80.82) and increased by about 5% for the period 1960-1970 and 30%
for the period 1970-1980. The number of x-ray machines was estimated
from the 1970-1980 trend to be 14,700 in 1985. We then estimated the
number'of potentially exposed workers using the value 1.18 workers per
chiropractic x-ray machine given by Fess (Fe69).
c. Podiatry
The number of podiatrists was estimated to increase by about 5%
and 25%, respectively, for the periods 1960-1970 and 1970-1980 (PHS82).
The number of podiatrists in 1985 was estimated to be 10,800 in 1985
(PHS82). We found that the number of podiatry x-ray machines estimated
from the HEW/HHS reports (HEW65-79, HHS80.82) increased by about 25%
and 35% for the periods 1960-1970 and 1970-1980, respectively. The
1985 number of x-ray machines was estimated from the 1975-1980 trend to
be 7,100. Because there are only about 30% fewer x-ray machines than
podiatrists, the value of 2 workers per podiatry x-ray machine cited by
Fess (Fe69) seems high. We therefore assumed 80% of active podiatrists
for the period 1960-1975 and 90% thereafter as an estimate of poten-
tially exposed workers in podiatry. The resultant number of workers
per x-ray machine is 1.5 for the period 1960-1970 and 1.4 after that.
Table A-4 gives the results for veterinary medicine, chiropractic
medicine, and podiatry. The number of x-ray machines was used as the
basic index for veterinary and chiropractic medicine; the number of
professional veterinarians and chiropractors as derived indexes. For
A-23
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podiatry, the number of podiatrists was used as the basic index, and
the number of x-ray machines was used as a derived index. The total
estimated number of potentially exposed workers roughly doubled over
the period 1960 to 1985 for these groups of workers. Although the
accuracy of these estimates may not be high, the combined contribution
of these workers to the medical category was only about 8-9%.
5. Summary of Medical Workers
A summary of the number of potentially exposed workers in medicine
is given in Table A-5. This work force can be divided into nearly
constant fractions since 1960: dental subcategory, about 44%; combined
veterinary, chiropractic, podiatry, about 8%; and combined hospital and
private practice, about 48%. During the period 1960-1980, the number
of workers in dentistry increased by a factor of 1.9, in hospitals by a
factor of 4.2, and in private practice by a factor of 1.4. As shown in
Table A-2, the effective number of hospital-based radiologists increased
by a factor of about 3, and the number of byproduct licensees in hospi-
tals increased by a factor of about 4, during the same period.
Table A-5. Estimated number of potentially exposed
workers in medicine, 1960-1985
occupation
Dentistry
Private Practice
Hospital
Veterinary Medicine
Chiropractic Medicine
Podiatry
Total
3
Number (10 )
1960
134
111
30
11
11
5
302
1965
150
116
48
12
11
6
343
1970
177
123
70
13
12
6
401
1975
215
136
96
17
14
7
485
1980
259
155
126
21
15
8
584
1985
304
180
162
26
17
10
699
A-24
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The trends of potentially exposed workers in medicine and its sub-
categories are shown in Figure A-4, along with the trends in numbers of
x-ray machines (medical and dental), all physicians, active civilian
dentists, active nonfederal radiologists, registered nurses (PHS80,
DOC81), workers in hospitals and health services (BLS79.83; DOC75,81;
SeSl), and dollars spent for personal health care (DOC81). The work
force in the health services industry increased by a factor of 3.4
between 1960 and 1980 (BLS79.83). Personal health care expenditures
increased by a factor of 9 for the same period. The number of physi-
cians and active civilian dentists increased by factors of 1.6 and 1.4,
respectively, while active nonfederal radiologists increased by a factor
of 2.9. The total number of potentially exposed workers in medicine
increased by a factor of 1.9 for the same period.
The total number of potentially exposed workers in medicine had con-
sistent correlation with the number of medical and dental x-ray machines
and the number of medical byproduct licensees. This would be expected
for x-ray machines, and they were used as the basic index for many sub-
categories. However, the correlation with the number of professionals
is also important since we relied primarily on number of professional
workers for estimating the number of workers in this work force. The
ratio of all potentially exposed workers in medicine to the total number
of medical and dental x-ray machines has been nearly constant at about
1.8 since 1965. The ratio of potentially exposed workers in medicine
to the number of medical byproduct licensees has remained about 100
since 1965.
B. Industry
The use of the number of professionals as a basic index to estimate
the number of potentially exposed workers generally worked quite well
in medicine, but is not readily applicable to industry because there
are few well-defined professional groups using sources of radiation.
The obvious exception is industrial radiography. Therefore, the basic
A-25
-------
'Potentially Exposed Workers
Personal
Health Care
Workers in
Health Services
Workers in
Hospitals
Registered
Nurses
All Physicians
X-ray Machines
(Medical & Dental)
Active
Civilian
Dentists
Active
Nonfederal
Radiologists
1960
1970
1980
Figure A-4. Trends of health care costs, health care workers, and
x-ray machines in medicine, U.S., 1960-1985.
A-26
-------
index data used for industry included (1) the number of radioactive
byproduct material licensees of NRC and Agreement States (NRC65-82).
(2) the number of facilities using nonmedical x-ray machines, and (3)
the number of particle accelerator users (HEW65-79; HHS80.82). These
data are reasonably reliable since 1965; the corresponding numbers for
i960 were estimated by back extrapolation of 1965-1980 trends.
The number of byproduct licensees in industry is reported by NRC
(formerly ABC) for only two categories: industrial radiography and
industrial "total" (NRC65-82). The further separation of industrial
"total" licensees into "manufacturing and distribution" and into "other
users" was used in special NRC studies for the years 1975, 1978, and
1979 (Co78; Bro81,82,83a,83c). We adopted this same separation and
made extrapolations for the periods before and after the NRC studies.
Industrial radiography depends primarily on the use of byproduct
material sources, although there is some use of industrial x-ray
machines (EPA83). Thus, the number of byproduct licensees of NRC
and NRC Agreement States was used as a basic index, with a small
adjustment for industrial x-ray machines, for estimating the numbers
of potentially exposed workers in industrial radiography. The numbers
of manufacturing and distribution licensees were determined from NRC
studies (Co78; Bro81,82,83a,83c). These were used, with a small adjust-
ment for industrial x-ray machines and particle accelerators, as the
basic index to estimate the number of potentially exposed workers in
manufacturing and distribution. The data for the two basic indices,
numbers of licensees and numbers of facilities, for other users came
from the remaining fraction of industry licensees and remaining numbers
of facilities using industrial x-ray machines and particle accelerators.
The small adjustments noted above to the basic indices for industrial
radiography and manufacturing/distribution involved apportionment of
industrial x-ray machine and particle accelerator registrants or facili-
ties. The number of facilities using industrial x-ray machines was
apportioned among the three subcategories according to the corresponding
A-27
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distribution of byproduct licensees in industry. Particle accelerator
users were similarly distributed to other users and to manufacturing
and distribution subcategories after apportionment of a fraction to
medicine based on the ratio of medical byproduct licensees to total
byproduct licensees.
The number of potentially exposed workers per licensee in industrial
radiography was determined from AEC film badge studies (AEC71) and NRC
occupational exposure reports (Co78; Bro81,82,83a). Similarly, the num-
ber of workers per licensee in source manufacturing and distribution was
obtained from these and other NRC studies (Co78; Bro81,82,83a; NRC80).
There were two separate components to estimation of workers in the
other industrial users subcategory: NRC licensees and facilities using
industrial x-ray machines and particle accelerators. The number of
workers per licensee was obtained from NRC studies (Co78; Bro81,82,83a;
NRC80). The number of workers per facility was estimated from commer-
cial dosimetry data for facilities using industrial x-ray units and for
particle accelerator user facilities. This number of workers was
reduced 20% to account for the overlap in use of different radiation
sources by the same licensee-registrant (EPA78; Bro81,82).
A summary of the estimated numbers of potentially exposed workers
in industry is given in Table A-6 for the period 1960 to 1985. we also
examined the reasonableness of the increase in the number of these
workers compared to other relevant factors. Our results show the
average growth rate of the number of potentially exposed workers per
year in industry for the period of 1960 to 1980 to be about 9.5%. We
compared this growth rate with the growth rate of three broad industrial
groups for the same time period. The average growth rates per year of
manufacturing, construction, and mining work forces were 1% to 2% for
the period 1960 to 1980 (DOC81). The average growth rates per year for
industrial byproduct licensees and number of registrant facilities were
both about 4% during the period of 1965 to 1980 (NRC65-82; HEW65-79;
A-28
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Table A-6. Estimated number of potentially exposed workers in industry, 1960-1985
Occupation 1960 1965 1970 1975 1980 1985
Industrial Radiography
Workers (103) 2 6 12 17 27 32
Basic Index
Licensees (103)(a) 0.4 0.6 0.8 0.8 1.0 1.1
Workers/Licensee(b) (5) (10) (15) (21) (27) (29)
Hanufacturing/Di stribution
Workers (103) 2 5 8 20 29 34
Basic Index
Licensees (103)(a)
Workers/Licensee {b)
Other Users
Workers (lO3)^
0.4
(5)
46
0.6
(8)
63
0.7
(12)
102
0.8
(25)
165
0.7
(41)
249
0.8
(42)
356
Two Basic Indices Combined
(i) Licensees (103)(a>
Workers/Licensee tb>
(ii) Facilities (103)(d)
Workers/Facility(e)
4
(7)
3
(6)
4.4
(8)
4
(7)
4.8
(14)
5
(7)
6.9
(17)
6
(8)
8.6
(19)
7.8
(11)
11.0
(21)
9.6
(13)
Industry Total (103) 50 74 122 202 305 422
(a)Licensees refers to NRC or NRC Agreement State licensees for each subcategory.
(b)Estimated or extrapolated from AEC/NRC and other studies (AEC71; Co78;
Bro81,82,83a; EPA78; NRC80).
tc)Sum of potentially exposed workers from licensees and facilities.
^Facility refers to those using nonmedical x-ray machines and to particle
accelerator users for "other users" subcategory.
(^Estimated or extrapolated from commercial dosimetry data.
A-29
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HHS80.82). From the product of the general work force growth rate (1%
to 2%) and the industrial byproduct licensee growth rate (4%), we obtain
an overall average annual growth rate of about 4% to 8%. This rate is
reasonably consistent with the 9.5% annual growth rate estimated here
for potentially exposed workers in industry.
C. The Nuclear Fuel Cycle
The number of potentially exposed workers in the nuclear fuel cycle
was estimated almost entirely from NRC and AEC/DOE data. The power re-
actor subcategory has contained the largest number of workers since the
early 1970's, whereas the fuel fabrication and reprocessing subcategory
previously contained the largest number. Before the late 1970"s, ura-
nium enrichment was estimated to contain the largest number of workers
among the remaining subcategories (uranium enrichment, nuclear waste
management, and uranium mills).
The numbers of nuclear fuel cycle workers for 1975, 1978, 1979, and
1980 were obtained directly from NRC and DOE reports (Co78; Bro81,82,
83a; DOE77-82). The numbers of workers in other years were estimated
by modeling available data.
The number of licensees in fuel fabrication and reprocessing before
1973 was estimated by back extrapolating the number of licensees after
1973 (Bro82,83a), according to the observed trend of number of fuel
fabrication facilities between 1967 and 1976 (NRC78). Similarly, the
number of workers per licensee before 1973 was back extrapolated from
the 1967 to 1976 trend in the number of employees per fuel fabrication
facility (NRC78).
The number of potentially exposed workers for power reactors before
1969 was estimated from AEC film badge studies (AEC68a,68b,70) and
number of reactors (AIF80; Bro82,83a). The number of workers after
1969 was obtained directly from NRC reports (Co78; Bro83a,83b).
A-30
-------
The number of workers In uranium enrichment since 1974 was obtained
directly from ERDA/DOE reports (DOE76-82). The number of workers in
uranium enrichment before 1974 was back extrapolated from AEC data
(DOE76-82).
The number of workers in uranium mills was estimated from NRC
reports (Co78; NRC78; Bro81,82). The number of workers in radioactive
waste management was estimated from AEC film badge studies for the
period 1967 to 1971 (AEC68a,68b,70,72,73) and NRC reports (Co78; Bro81,
82,83b,83c).
The number of workers in the nuclear fuel cycle for 1985 was pro-
jected from the 1975 to 1980 trend in each subcategory. we summarize
our results for the entire nuclear fuel cycle in Table A-7.
Table A-7. Estimated number of potentially exposed
workers in the nuclear fuel cycle, 1960-1985
Occupation
Power Reactors
Fuel Fab. & Repro.
Uranium Enrichment
Nuclear Waste Mgt.
Uranium Hills
Number (103)
1960
0.2
2.5
0.6
0.1
0.6
1965
0.7
4.9
1.8
0.2
1.5
1970
7.5
8.4
2.0
0.3
1.7
1975
54.8
11.6
7.5
0.3
2.3
1980
133.7
10.2
1.9
0.7
4.8
1985
183
9
2
1
5
Total* 4 9 20 76 151 200
*Total numbers of workers have been rounded to the nearest thousand.
D. Government
We summarize, in Table A-8, for the period 1960 to 1985, the
results of our analysis of numbers of potentially exposed or monitored
A-31
-------
Table A-8. Estimated number of potentially exposed
workers In government, 1960-1985
Agency
Number (10 )
1960
1965
1970
1975
1980
Total
130
231
200
184
204
1985
Dept. of Energy^ a^
Dept. of Defense
Air Force
Army
Navy
Other agencies^)
NASA
NBS
NIH
PHS
VA
80
45
7
16
22
5
0.2
0.1
0.5
1.5
2.3
132
93
16
21
56
6
0.3
0.2
0-9
2.1
3.0
95
97
13
23
61
8
0.5
0.2
1.3
2.7
3.6
81
92
16
16
60
11
1.4
0.4
2.2
2.4
4.9
84
103
18
21
64
17
0.9
0.4
4.1
5.9
5.7
90
110
18
22
70
20
0.9
0.5
5.2
6.9
6.2
220
(^Excludes data on uranium enrichment workers (see Table A-7) and
visitors (see Table 5 and Appendix C).
Safety and Health Administration data not included (see
Appendix C). Total numbers of workers have been rounded to the
nearest thousand.
NASA National Aeronautics and Space Administration.
NBS National Bureau of Standards.
NIH National Institutes of Health.
PHS Public Health Service.
VA Veterans Administration.
workers for the Department of Energy (DOE); the Air Force, Army, and
Navy of the Department of Defense (DOD); Public Health Service (PHS)
(workers in various agencies and facilities covered by the PHS
Personnel Monitoring Program—see Table D-6 for details); National
Aeronautics and Space Administration (NASA); National Bureau of
Standards (NBS); National Institutes of Health (NIH); and Veterans
Administration (VA).
A-32
-------
The DOE (previously the ABC) and DOD subcategories contained the
majority of workers In the government category. The remainder came
from PHS, NASA, NBS, NIH, and VA, and accounted for less than 4% before
the 1970s.
The ABC and ABC contractors compiled annual exposure statistics
for employees beginning In 1955. Exposure summaries for 10 separate
occupational categories have been published since 1974.
The Navy has reported the largest number of monitored workers In
DOD since 1960. The numbers of workers in nuclear ships. Navy ship-
yards, and private shipyards have been reported for the years 1954-1983
by the Naval Nuclear Propulsion program (Sc84). The Navy's Bureau of
Medicine and Surgery (BUMED) reports annual exposure of personnel In
nuclear ships. Navy shipyards, and dental/medical activities, but not
in private shipyards (Co80, R182). We have adjusted the Navy's Naval
Nuclear Propulsion and BUMED data to correct for overlap.
The numbers of workers in the Air Force and the Army for 1960 and
1970 were obtained from a previous EPA study (K172). The corresponding
numbers for 1965 were interpolated from the 1960 and 1970 data by com-
parison with the 1960-1970 trends In the Navy.
We obtained exposure statistics from other government agencies,
except VA, for the period 1975 to 1980. We estimated the number of
workers in VA from their numbers of dentists, dental auxiliaries,
radiologists, and other medical workers between 1975 and 1982. The
number of potentially exposed workers in the VA before 1975 was extra-
polated from the trend observed for workers monitored by PHS. It was
found to be consistent with the trend for the total number of all VA
employees.
The number of potentially exposed workers in 1960 for the NIH,
NASA, and NBS was obtained from our earlier study (Co80). The number
A-33
-------
of workers for the PHS in 1965 was linearly interpolated from the data
available for 1960 and 1970. The combined estimate of 2,000 workers
(K172) for NASA, NBS, and NIH in 1970 was apportioned according to the
fractions observed in 1980; the corresponding 1965 values were obtained
by interpolation.
B. Miscellaneous Occupations
1. Education
The description and monitoring of potentially exposed workers in
educational institutions are not well known, as there are few published
data. We included only faculty and associated staff in our main sum-
mary of occupational exposure (Table 4). Students are considered
separately below.
We used the same basic method to estimate the number of workers in
education as used in our 1975 study (Co80). The numbers of faculty and
associated staff are based on the number of students estimated to be in
programs involving radiation sources. Workers in hospitals associated
with educational institutions already are accounted for in the medicine
category. We recognize that each educational Institution is unique and
that research programs may have little or no relationship to the number
of students in various programs. Nevertheless, we have based the num-
ber of potentially exposed workers on the number of students. These
estimated numbers of workers are consistent with the results of NRC
studies (Bro81,82).
a. Students
Students pursue studies involving radiation sources in a variety
of medical, allied health, and science related fields. We consider each
of these fields separately.
A-34
-------
Medical school enrollment In health professions was taken from "A
Report to the President and Congress," April 10, 1980 (PHS82). Numbers
of medical students for 1980 and 1985 were extrapolated from 1975-1979
values. Few undergraduate physician and osteopathic students have po-
tential for exposure. Potential exposure of graduate medical students
occurs in hospitals or other science degree programs, where they would
already be accounted for. At some point in their studies, all students
in programs for dentists, podiatrists, veterinarians, and chiropractors
were assumed to have potential for radiation exposure. In any given
year, 50% of dental, 25% of veterinary, 100% of chiropractic, and 100%
of podiatric students were assumed to be enrolled in classes involving
radiation. The total number of these students for 1980 was estimated
to be 22,250.
We assumed that students in five allied health programs had classes
involving sources of radiation. All those studying to become dental
assistants, radiographers, therapy technologists, nuclear medicine
technologists, and 50% of dental hygienists were included. Graduate
students were neglected in these programs. The total number of these
allied health students for 1980 was estimated to be 33,490.
For science programs in universities and colleges, we assumed
that the number of bachelor degree recipients in any year represented
approximately 25% of the undergraduate students in these fields. The
number of graduate students was estimated by assuming that the number
of master and doctor degree recipients in any year represented 50% and
25%, respectively, of these students. The number of graduates were ob-
tained from "Digest of Education Statistics, 1982" (Gr82). Based on
personal communications with faculty and staff of several institutions,
we estimated that students were in classes involving radiation sources
each year as follows: 10% of physics (general) majors, 5% of chemistry
(general) majors, 5% of biological sciences majors, and 100% of nuclear
physics and nuclear engineering majors. Students majoring in general
biology were not included as biological sciences majors. Assuming the
A-35
-------
above values, the number of undergraduate and graduate students in
science and engineering courses involving radiation was 11,410 in 1980.
The total number of all students in programs involving sources of radia-
tion was estimated to be 67,150 in 1980.
b. Faculty and Associated Staff
We estimated the number of potentially exposed faculty and staff
workers from the estimated number of students (undergraduate and grad-
uate) in programs that involve sources of radiation and from student/
faculty and staff/faculty ratios. We estimated staff/faculty and stu-
^
dent/faculty ratios from personal communications with radiation protec-
tion personnel at educational institutions. These ratios were not based
on a representative survey and therefore can provide only rough esti-
mates of potentially exposed faculty and staff. The derivation of the
numbers of faculty and associated staff estimated to be potentially
exposed workers is summarized in Table A-9.
c. Summary
The estimated number of students and faculty associated with
sources of radiation at educational instititutions is, at best, a rough
approximation. Although there is reliable published data on numbers of
students and faculty, there is little concerning those potentially or
actually exposed to sources of radiation. Our estimates of the number
of workers in education are consistent with those projected by the NRC
for their academic licensees (Bro82), if we assume an equal number of
workers under Agreement State licenses and that about half of all NRC
and Agreement State academic workers are found in academic health
clinics and hospitals. It is known that NRC estimates for educational
institutions also contain health clinic and hospital exposure data.
Such clinic and hospital workers accounted for about 40% and 60% of the
monitoring data at the University of Indiana (Bri83) and University of
Missouri at Columbia, Mo. (Le83), respectively, that were used for the
A-36
-------
Table A-9. Estimated number of potentially exposed faculty and
associated staff in educational institutions, 1980
Education program
Medical
Allied
Health
Sciences
Total
Undergraduate Program
Students
Faculty/Student
Faculty
Graduate Program
22,250 33,490
0.1 0.1
2,230
3.350
7,890
0.1
790
6,370
Students
Faculty/Student
Faculty
Faculty subtotal
Staff/Faculty
Associated Staff
Total*
3,520
0.5
1,760
2,230 3,350 2,550
1.0 1.0 5.0
2,230 3,350 12,750
1,760
8,130
18,330
26,500
*Does not include students (see Table 5 and Appendix C).
NEC estimates (Bro82). we considered such workers separately in the
hospital workers subcategory.
Some students are undoubtedly monitored for exposure to radiation.
However, there appear to be relatively few. Persons less than 20 and
22 years old comprise less than 5% and 15%, respectively, of the com-
merical dosimetry data for monitored individuals in education. We have
not included students in our estimates of the number of radiation work-
ers. If we were to count only the 33,490 students in the allied health
subcategory. who are in training for specific jobs involving the use of
radiation, as potentially exposed workers, the estimated number of work-
ers in education would increase from about 26,500 to about 60,000.
A-37
-------
The number of potentially exposed workers in education was also
estimated for the years 1960, 1965. 1970, 1975, and 1985 (Table A-11).
There was good correlation between the trends in number of educational
byproduct licensees of the NEC and the estimated number of workers for
the period 1960-1980.
2. Transportation
Many radioactive material shipments are low in radioactivity and do
not require use of licensed shippers and handlers. Thus, not all trans-
porters of radioactive materials are NRC or State licensed. Our analy-
sis of transportation workers is based largely upon NEC's "Final Envi-
ronmental Statement on the Transport of Radioactive Materials by Air
and Other Modes" (NRC77b). This report provided collective dose and
some worker dose estimates for 1975 and 1985. Since this NRC study
relied on exposure data available in 1975, changes in shipping volume
or work practices different from those projected would invalidate these
dose estimates. We examined the 1980 commercial data sample for con-
sistency with the NRC projections of mean doses. Unfortunately the
data sample for transportation workers was questionable, since it con-
tained more than half of all the commercial dose records that were
greater than 12 rems (these high records averaged 25 rems). After in-
vestigating the commercial dosimetry data and consulting the Department
of Transportation, we concluded that these high records were not relia-
ble. If these high records are not included, the mean annual dose, was
60 mrem. This is in good agreement with the projection of 70 mrem based
on the NRC study results.
Estimated numbers of potentially exposed workers associated with
each transport mode (Table A-10) were obtained by dividing NRC collec-
tive dose estimates by best estimates of average doses. For the air-
craft transport mode, the mean average dose of 90 mrem for workers was
based on studies at five major airports (NRC77a). The mean annual dose
of 70 mrem assumed for truck, rail, and ground handlers, was based on
A-38
-------
Table A-10. Estimated number of potentially exposed
workers in transportation, 1980^)
Transport mode
Primary Mode
Aircraft
Truck
Rail
\
Secondary Mode
Ground handlers
X-ray baggage check
All Workers
Number
of
workers
1,800
11,400
1,400
25.700
4,100
50,400
Mean dose
equivalent
(mrem)
90
70
70
70
20
70
Collective dose
equivalent
(person-rem)
700
800
100
1800
80
3480
(a>Based on NRC and DOT studies (NRC77b; DOT81).
(b^Does not include passenger aircraft crew members (39,000) and
flight attendants (58,000) (see Table 5 and Appendix C).
our assessment of drivers and handlers, as characterized by an NRC
study (NRC77b). The numbers of workers in transportation for 1975 and
1985 were similarly estimated from NRC data (NRC77b). The numbers of
workers for the years 1960 to 1970 were obtained by back extrapolation
of the 1975 to 1985 trend.
The number of operators of security x-ray baggage checks at air-
ports was estimated as 4,100 from the number of x-ray units reported
to Congress by the Federal Aviation Administration (DOT81). From the
above, we estimate a total of about 50,000 workers potentially exposed
in transportation in 1980.
There were an estimated 58,000 flight attendants and 39,000 flight
crew members for passenger aircraft in 1980. These workers receive
most of their doses from increased exposure to cosmic rays at high
altitudes. Their mean annual dose from cosmic radiation is estimated
to be 170 mrem (NRC77b). Flight attendants and crew members also
A-39
-------
receive very low exposures from radioactive materials on passenger air-
craft; their estimated mean annual doses are 3 mrem and 0.5 rarem,
respectively (NRC77b). Flight attendants and flight crew members are
listed in our summary for additional groups (Table 5); their mean annual
dose from transported radiation sources is only a few percent of their
cosmic radiation doses.
III. SUMMARY
Table A-ll summarizes the number of U.S. workers potentially
exposed to radiation by category and subcategory from 1960 through
1985. Government and nuclear fuel cycle workers together have com-
prised about one-fourth of all potentially exposed workers since 1960,
except for 1965, when these two categories were about one-third. This
exception was due to the 65% and almost 250% increases in the number of
workers in the AEC and Navy, respectively. Workers in medicine and
industry have comprised about two-thirds of all potentially exposed
workers since 1970.
The dentistry subcategory contained the largest number of workers
of all subcategories between 1960 and 1980. Workers at power reactors
exhibited the largest growth rate during this period. Industrial "other
users" and hospital subcategories exhibited the second and third largest
growth rates, respectively. Before 1975, dentistry, private practice,
industrial "other users," DOE (formerly AEC/ERDA), and DOD were the
five largest subcategories. Since 1975, dentistry, private practice,
hospital, industrial "other users," and power reactors have been the
five largest subcategories.
The growth in the number of all potentially exposed workers (U.S.
Total) and workers in each of the five categories are compared with the
growth of the U.S. population, the U.S. labor force, and the U.S. gross
national product (GNP; 1980 dollars) in Figure A-5. The number of
A-40
-------
Table A-ll. Estimated number of potentially exposed
workers in the United States, 1960-1985
Declination
Number (103)
1960
MEDICINE
Dentistry
Private Practice
Hospital
Veterinary
Chiropractic
Podiatry
Subtotal
INDUSTRY
Radiographers
Manufac. & Dist.
Other Users
Subtotal
NUCLEAR FUEL CYCLE
Power Reactors
Fuel Fab. & Repro.
Uranium Enrichment
Nuclear Waste Mgt.
Uranium Mills
Subtotal
GOVERNMENT
Dept. of Energy ^a)
Dept. of Defense
Other Agencies^)
Subtotal
MISCELLANEOUS
Education
Transportation
Subtotal
Total
134
111
30
11
11
5
302
2
2
46
50
0.2
2.5
0.6
0.1
0.6
4
80
45
5
130
10
7
17
503
1965
150
116
48
12
11
6
343
6
5
63
74
0.7
4.9
1.8
0.2
1.5
9
132
93
6
231
17
12
29
686
1970
177
123
70
13
12
6
401
12
8
102
122
7.5
8.4
2.0
0.3
1.7
20
95
97
8
200
22
20
42
785
1975
215
136
96
17
14
7
485
17
20
165
202
54.8
11.6
7.5
0.3
2.3
76
81
92
11
184
25
31
56
1003
1980
259
155
126
21
15
8
584
27
29
249
305
133.7
10.2
1.9
0.7
4.8
151
84
103
17
204
26
50
76
1320
1985
304
180
162
26
17
10
699
32
34
356
422
183
9
2
1
5
200
90
110
20
220
28
71
99
1640
ta>Uranium enrichment workers are included in nuclear fuel cycle
category. Excludes data on visitors (see Table 5).
^Excludes data from MSHA for miners (see Table 5).
^Excludes data on students, passenger aircraft crew members, and
flight attendants (see Table 5).
A-41
-------
1013
101
108
107
106
Medicine
105
104
Government*
** -
Industry* .*»•**"
^^ * "^^
_^MI * *^^
•** * ^^
Miscellaneous*
..•••**'
X
/
Nuclear Fuel Cycle*
•Potentially Exposed Workers
103
U.S. GIMP ($1980)
U.S. Population
U.S. Labor Force
I960
1970
1980
Figure A-5. Trends of U.S. population, labor force, gross
national product, and potentially exposed workers, 1960-1985.
A-42
-------
potentially exposed workers per 1,000 population increased from 3 in 1960
to 6 in 1980 (7 projected for 1985). The number of these workers per
1,000 labor force workers increased from 1 in 1960 to 12 in 1980 (14 pro-
jected for 1985). The number of potentially exposed workers per million
dollars of GNP decreased from 1 in 1960 to 0.5 in 1980 (0.4 projected for
1985).
A-43
-------
APPENDIX B
DOSE DISTRIBUTION ESTIMATES
-------
CONTENTS
Page
I. INTRODUCTION B_7
II. DISTRIBUTIONS OF WORKERS BY DOSES B-9
A. Medicine B-ll
B. Industry B-14
C. Nuclear Fuel Cycle B-17
D. Government B-21
E. Miscellaneous B-25
F. U.S. Total B-27
III. DISTRIBUTIONS OF COLLECTIVE DOSES B-32
IV. AGE DISTRIBUTIONS B-36
A. Distribution of Worker Ages B-36
B. Distribution of Collective Doses by Worker Age B-38
C. Summary B-41
TABLES
B-l. Summary of information used to estimate the numbers and
dose distributions of potentially exposed workers, 1980 . . B-8
B-2. Summary of mean annual and collective doses to potentially
exposed workers in medicine, 1960-1985 B-16
B-3. Summary of mean annual and collective doses to potentially
exposed workers in industry, 1960-1985 B-19
B-4. Summary of mean annual and collective doses to potentially
exposed workers in the nuclear fuel cycle, 1960-1985. . . . B-21
B-5. Summary of mean annual and collective doses to potentially
exposed workers in government, 1960-1985 B-23
B-3
-------
TABLES (Continued)
Page
B-6. Summary of mean annual and collective doses to potentially
exposed workers in education and transportation,
1960-1985 B-27
B-7. Summary of mean annual dose to potentially exposed
workers, 1960-1985 B-30
B-8. Summary of annual collective dose to potentially exposed
workers, 1960-1985 B-31
B-9. Estimated mean and median age of workers potentially
exposed to radiation, by sex, 1980 B-42
FIGURES
B-l. Number of workers potentially vs. actually exposed,
1975 and 1980 B-10
B-2. cumulative percent of workers by fraction of measurably
exposed workers in selected groups from commercial
dosimetry data, 1975 and 1980 B-10
B-3. Trends of mean annual dose equivalents for workers in
hospitals, private practice, dentistry, and for all
medical workers as estimated from various data B-13
B-4. Dose distributions for workers in medicine B-15
B-5. Dose distributions for workers in industry B-18
B-6. Dose distributions for workers in the nuclear fuel cycle . . B-20
B-7. Dose distributions for workers in government B-24
B-8. Dose distributions for workers in miscellaneous
occupations B-26
B-9. Dose distributions for all workers B-28
B-10. Collective dose distributions for males, females, and
all workers, 1980 B-34
B-4
-------
FIGURES (Continued)
Page
B-ll. Collective dose distributions for all workers B-35
B-12. Male and female age distributions for potentially exposed
workers and age distributions for the U.S. labor
force, 1975 and 1980 B-37
B-13. Age distributions for potentially exposed workers and U.S.
labor force, 1975 and 1980, and U.S. population, 1980 . . . B-39
B-14. Age distributions for potentially exposed workers and
of collective dose, 1975 and 1980 B-40
B-5
-------
APPENDIX B
DOSE DISTRIBUTION ESTIMATES
I. INTRODUCTION
In order to determine dose distributions for the different groups
of exposed workers, we analyzed a variety of data. For many worker
groups we used commercial dosimetry data, which had high accuracy, but
unknown representativeness. In such cases, it was necessary to examine
other sources of data to establish whether or not the data we used were
reasonably representative. We also examined trends in the numbers of
workers receiving less-than-measurable doses as well as numbers of
workers receiving the highest doses. These and other considerations
are examined here for each category and subcategory of potentially
exposed workers.
Table B-l provides a summary of sources and sample size of the
data sets used to determine the dose distributions of workers for each
subcategory. Some of the sets of data are almost complete and, there-
fore, present few analysis problems. Most others are sizable samples.
In a few cases, however, notably for workers in dentistry, and, to a
lesser extent, for workers in industry and transportation, the numbers
of workers are large, and the size of the sample of exposure data is
small.
Statistical analyses can reveal characteristics that are useful
for examining the reliability of data and in making comparisons between
B-7
-------
Table B-1. Sunmary of information used to estimate the numbers and dose
distributions of potentially exposed workers, 1980
Occupational
category
MEDICINE
Dentistry
Private Practice
Hospital
Veterinary
Chiropractic
Podiatry
INDUSTRY
Radiography
Manufacturing
& Distribution
Other Users
NUCLEAR FUEL CYCLE
Power Reactors
Fuel Fabrication
& Reproduction
Uranium Enrich.
Nuclear Waste
Management
Uranium Hills
GOVERNMENT
Dept. of Energy
Dept. of Defense
Other Agencies
MISCELLANEOUS
Education
Transportation
U.S. TOTAL
Index used Number of
to estimate potentially
number of exposed workers
workers (103)
Sum of professional dental workers
Number of private practice
radiologists and x-ray machines
Number of hospital -based radiologists
Number of veterinary x-ray machines
Number of chiropractic x-ray machines
Number of podiatrists
Number of industrial radiography
licensees
Number of manufacturing and
distribution licensees
Number of other licensees and
facilities
Number of monitored workers
Number of monitored workers
Number of monitored workers
Number of monitored workers
Number of monitored workers
Number of monitored workers
Number of monitored workers
Number of monitored workers
Number of students in radiation-
related courses
Number of transportation workers
584
259
155
126
21
15
8
305
27
29
249
151.3
133.7
10.2
1.9
0.7
4.8
204.3
83.6
103.5
17.2
76
26
50
1.320
Sample size used
to obtain dose
distribution
(t of workers)
28.5
3.1
21.9
93.3
28.1
7.7
0
45.3
dose distribution as used in the 1975 report (Co80).
(^Exposure data for education included faculty and students and was separated according
to age to characterize the annual doses to faculty and students.
available data for transportation corresponded to workers at airline baggage
checks.
B-8
-------
different sets of data. We examined a number of these characteristics
for occupational exposure data and give examples in this appendix, pri-
marily for the years 1975 and 1980, for which we had data for almost
all occupational categories. Our analyses showed, for example, that
1980 Federal and commercial data were more self-consistent than were
those for 1975. Figure B-l shows the number of measurably exposed
workers as a function of the total number of potentially exposed workers
for the five major categories and the U.S. total in 1975 and 1980. The
fraction of workers measurably exposed to radiation varied from one
worker group to another. However, we found that the fraction of these
workers was more consistent in the 1980 data than in the 1975 data.
For example, the characteristics of the 1975 data for government and
nuclear fuel cycle workers look much like that of the 1980 data.
Figure B-2 shows the cumulative frequency of workers not exceeding a
certain fraction of workers with a measurable dose in 1975 and 1980,
according to the commercial data. From this data presentation we see
that the distribution of measurably exposed workers was more nearly a
normal distribution in 1980 than in 1975. in addition, the median
fraction (52%) of measurably exposed workers in 1980 was approximately
double the median fraction (29%) in 1975. This result is consistent
with the observed trend in Figure B-l.
II. DISTRIBUTIONS OF WORKERS BY DOSES
Dose distributions for the various groups of potentially exposed
workers were obtained or constructed from the variety of available
data. Because of completeness of monitoring records, exposure informa-
tion for government and the nuclear fuel cycle workers provided relia-
ble dose statistics. Commercial data was particularly useful as it was
coded for different groups of workers and contained age and sex informa-
tion for about 50% of the individual dose records. Only these latter
dose records containing age and sex information were used for computing
mean doses, and these data also provided essentially all the age and
B-9
-------
10B
8
Q
tu
3
a:
o
1C
UJ
m
10"
10"
INDUSTRY
GOVERNMENT
I
GOVERNMENT
A INDUSTRY
A 1975
• 1980
105 106
NUMBER OF POTENTIALLY EXPOSED WORKERS
107
Figure B-1. Number of workers potentially vs. actually exposed,
1975 and 1980.
99.99
99.9
99
95
u. go
O
80
70
60
50
40
30
20
D
O
10
5
10 20 30 40 50 60 70
FRACTIONS OF WORKERS WITH A MEASURABLE DOSE (%)
80
90
Figure B-2. Cumulative percent of workers by fraction of measurably exposed workers
in selected groups from commercial dosimetry data, 1975 and 1980.
B-10
-------
sex data for this study. Although these data were assumed to be repre-
sentative, they were examined for irregularities by fitting the data to
the HLN model (see Appendix F). We briefly discuss the dose distribu-
tions found for each of the five major categories of workers below.
A. Medicine
The dose distributions used for each subcategory of medical
workers in 1915 and 1980 were constructed entirely from commercial
data. We examined the distributions for each medical worker group with
the HLN model to identify questionable data. The dose distribution for
each subcategory was obtained from the weighted sum of dose distribu-
tions from relevant worker groups.
Since the dose distribution for dental workers consisted of data
which comprised only 3% of the estimated number of those potentially
exposed in 1980, we compared its composition by sex to that for all
dental workers (PHS82). The consistency of the comparison provided
one confirmation of its representativeness. In addition, we compared
dose distributions of U.S. and West German dental workers (Dr81). We
found very similar dose distributions for both sets of data.
The dose distribution for workers in private practice was the
weighted sum of the dose distributions of workers in radiology and
seven groups of workers in private practice.
The dose distribution for hospital workers was calculated from the
sum of dose distributions for workers in seven hospital groups, weighted
according to statistics of the American Hospital Association (AHA76.81).
Since the largest hospital group (general medical and surgical hospi-
tals) contained more than 80% of all potentially exposed workers and
the second largest (university hospitals) more than 15%, the dose
distribution for workers in hospitals was effectively determined by
these two groups.
B-ll
-------
The distribution of doses for the combined workers in veterinary
medicine, chiropractic medicine, and podiatry was constructed from the
weighted sum of dose distributions for the chiropractic and veterinary
workers only, because only the mean dose was available for workers in
podiatry. For 1980, mean doses were estimated for each of these groups,
and are shown in Table 4. The total number of workers was adjusted to
include the numbers of workers in podiatry.
Dose distributions in each subcategory of medicine in 1960, 1965,
and 1970 were constructed from the dose distributions for 1975 and 1980
using the trends of mean annual dose for the period 1960-1980. Mean
annual doses for medical-byproduct-licensee workers were estimated
using HLN analysis of dose statistics from NRC reports (Co78; Bro81,82,
83c) and limited 1966-1971 film badge reports from REG and Agreement
States licensee data (AEC68a,685,70,71,73). The trend of these mean
annual doses is approximated by a simple model of 310 mrem in 1960 that
is halved every 14 years after that, as shown by the upper solid line
in Figure B-3. We assumed that the trend of mean annual doses for all
medical workers exhibits the same halving period, and fitted this trend
to the estimated annual doses for 1975 and 1980. The mean annual dose
for medical workers is shown by the lower solid line in Figure B-3. The
numerical values of mean annual doses found for all medical workers were
only about 60% of those determined by NRC for their medical licensees.
This is primarily due to the large number of dental workers included in
our analysis who have lower doses.
The mean annual doses to workers In hospitals and private practice
were obtained similarly (Figure B-3). The mean annual dose in dentis-
try, shown by the broken line in Figure B-3, was chosen so that the
collective dose for medicine would be equal to the sum of the collec-
tive doses from all subcategories for each year. The resulting annual
decrease (about 18%) of the mean annual dose to dental workers is very
close to the reported annual decrease (about 20%) of the mean exposure
per dental film at skin surface between 1960 and 1970 (Ma80).
B-12
-------
1000
500
Ui
8
Q
i
200
100
50
20
10
1960
O Medicine (EPA: 1975,1980)
if Hospital (EPA: 1975,1980)
•fr Private Practice (EPA: 1975,1980)
* Dentistry (EPA: 1975,1980)
D Medical Licensees (AEC: 1966-1971)
• Medical Licensees (NRC: 1975,1978-1980)
A Medical Licensees (Agreement States: 1968-1971)
1965
1970
1975
1980
1985
Figure B-3. Trends of mean annual dose equivalents for workers in
hospitals, private practice, dentistry, and for all medical
workers as estimated from various data.
The trend of mean annual doses for the combined workers In veteri-
nary medicine, chiropractic medicine, and podiatry was assumed to be
constant at 50 mrem because the dose changed only slightly from 1975
to 1980. These workers have contributed only a few percent of the
total collective dose in medicine since 1960.
As noted above, we assumed that the dose distribution for medical
workers in 1960, 1965, and 1970 could be derived from the 1975 dose
distributions using the trend of the AEC/NRC data for mean dose, as
analyzed by the HLN model (AEC68a,68b,70,71,73; Co78; Bro81,82,83c).
The method used was to shift the 1975 dose distributions in the direc-
tion of higher doses on lognormal probability paper so that the mean of
B-13
-------
the dose distribution agreed with the corresponding mean dose determined
in Figure B-3.
Figure B-4 shows the log-probability plots of the resulting dose
distributions tor medical workers in 1960, 1965, 1970, 1975, and 1980,
and for the various subcategories of workers in 1960, 1975, and 1980.
The curves were fitted to the estimated data using the HLN model.
The shapes of the sum of dose distributions for workers in
hospitals and private practice were in good agreement with dose
distributions for medical workers obtained from the data of ABC,
Agreement States, and NRC medical licensees since about 1965. The
primary difference in the shapes of dose distributions for medicine
and AEC/NRC medical licensees is accounted for by the Inclusion of the
contribution of the dose distribution in dental workers in the former
group.
Table B-2 gives a summary of mean annual dose and collective dose
equivalents to workers in medicine in 1960, 1965, 1970, 1975, 1980, and
1985. The 1985 estimates in Table B-2 were obtained by extrapolating
results shown in Figure B-3 and Table A-ll. These 1985 estimates
agreed well with those obtained from the log-log extrapolation of the
mean annual dose and the number of workers in medicine from the 1975-
1980 trend shown in Figure 11. All estimates in Table B-2 reflect the
trends of mean annual doses shown in Figure B-3 and dose distributions
shown in Figure B-4.
B. Industry
The 1975 and 1980 dose distributions for workers in each
subcategory in industry were primarily constructed from commercial
data. However, we constructed the dose distribution for workers in
industrial radiography from NRC reports (Co78; Bro81,82,83a), while the
dose distribution for workers in manufacturing and distribution was
B-14
-------
99.9999
99,999
99.99
99.9
40
30
20
0.01
1960
MEDICINE
A-—A MntMry
D D MnnPnctloi
. MMIal Otto
99.9999
99.999
99.99
09.9
1975
99.999
99.99
99.9
1980
MEDICINE
Dmlntry
o Private Practice
• Hotpital
A IMdicalOtlur
0.1 1
ANNUAL DOSE EQUIVALENT (ram)
10
Figure B-4. Dose distributions for workers in medicine.
B-15
-------
Table B-2. Summary of mean annual and collective doses to
potentially exposed workers in medicine, 1960-1985
Occupation
Dentistry
Private Practice
Hospital
Others*
Total
Occupation
Dentistry
Private Practice
Hospital
Others*
Total
Mean annual dose equivalent (rarem)
1960
110
280
400
50
190
Annual
1960
15
31
11
1
58
1965
80
230
300
50
160
collective
1965
12
26
15
1
54
1970
60
180
230
50
120
dose
1970
10
22
17
1
50
1975
40
140
190
50
100
equivalent
1975
8
18
18
2
46
1980
20
100
140
50
70
1985
10
80
100
60
50
3
( 10 person-rem)
1980
6
16
17
2
41
1985
3
14
16
3
36
*Veterinary medicine, chiropractic medicine, and podiatry.
based on both NRC reports (Co78; Bro81,82,83a) and commercial data. The
dose distribution for the remaining workers in industry ("other users")
was estimated from the sum of the dose distributions in eighteen indus-
trial worker groups from commercial data.
The dose distributions for workers in each subcategory of industry
for 1960, 1965, and 1970 were constructed from our analyses of 1966-1971
film badge reports for ABC and Agreement States licensees (AEC68a,68b,70,
71,73) and the trend of the corresponding dose distributions between 1975
and 1980.
B-16
-------
Figure B-5 shows the log-probability plots of dose distributions
for workers in industry in 1960, 1965, 1970, 1975, and 1980 in its three
subcategories for I960, 1975, and 1980. The smooth curves were fitted
to the estimated distribution data using the HLN model. The relative
shapes, positions, and trends of worker dose distributions among the
different subcategories shown in Figure B-5 were consistent for the
period 1960 to 1980. The dose distribution for all industry workers
was influenced most by the characteristics of the distribution for
"other users" workers. The shape of dose distributions above about
1 rera clearly became concave after 1970 for workers in industry.
The summary of mean annual dose and collective dose equivalents for
workers in industry and its subcategories is given in Table B-3. The
1985 estimates in Table B-3 were obtained from the log-log extrapolation
of mean annual dose and the number of workers according to their 1975-
1980 trends (See Figure 11). The mean dose for workers in each subcate-
gory has decreased since 1970 except for industrial radiography, which
has remained practically constant.
C. Nuclear Fuel Cycle
Data for the 1975 and 1980 dose distributions of workers in the
nuclear fuel cycle were obtained from NEC reports (Co78; Bro82,83a),
except for data on uranium enrichment workers, which were obtained
from ERDA/DOE reports (DOE76-82). We examined trends for the period
1960-1985 for three subcategories: power reactors, fuel fabrication and
reprocessing, and other (uranium enrichment, nuclear waste management,
and uranium mills).
The 1970 dose distribution for power reactor workers was obtained
from an NRC report (Bro83b). The dose distributions for workers in
each remaining subcategory for 1960, 1965, and 1970 were constructed
from the 1966-1971 film badge reports for AEC and Agreement states
licensees (AEC68a,68b,70,71,73) and the 1975-1980 trend of the dose
distribution in each subcategory.
B-17
-------
99.9999
99.999
99.99
99.9
1960
INDUSTRY
• • Industrial Radiography
D D Manufacturing and Distribution
A A Other Users
1975
INDUSTRY
• • Industrial Radiography
o G Manufacturing and Distribution
A A Other Usurs
99.9999
201—
0.01
1980
INDUSTRY
• • Industrial Radiography
a p Manufacturing and Distribution
A A Other Users
99.9999
0.1 1
ANNUAL DOSE EQUIVALENT (rem)
10
Figure B-5. Dose distributions for workers in industry.
B-18
-------
Table B-3. Summary of mean annual and collective doses to
potentially exposed workers in industry, 1960-1985
Occupation
Radiography
Hanufac. & Distr.
Other Users
Total
Occupation
Radiography
Hanufac. & Distr.
Other Users
Total
Mean annual dose
1960
630
320
210
230
Annual
1960
0.7
0.6
10
11
1965
490
360
210
240
collective
1965
3
2
13
18
1970
310
360
200
220
dose e
1970
4
3
20
27
equivalent (rarem)
1975
280
220
120
140
quivalent
1975
5
4
20
29
1980
290
110
110
120
do3 P
1980
8
3
27
38
1985
300
80
100
110
erson-rem)
1985
10
3
34
47
Figure B-6 shows the log-probability plots of dose distributions
for workers in the nuclear fuel cycle in 1960, 1965, 1970, 1975, and
1980 and for its three subcategories in 1960, 1975, and 1980. The
smooth curves were obtained from HLN fits of the data. The composite
dose distribution for workers in the entire nuclear fuel cycle most
closely followed the fuel fabrication and reprocessing sector before
1970 and the power reactor sector after 1970.
The dose distribution for all workers in the nuclear fuel cycle
shows the most pronounced concave shape in 1980. The distributions in
different years had the greatest similarity and overlap in the dose
range from 0.1 rem to 4 reras.
Table B-4 summarizes the mean annual dose equivalent and the
collective dose equivalent for workers in the nuclear fuel cycle and
B-19
-------
20*-^-
0.01
1960
NUCLEAR FUEL CYCLE
A Power Reactors
O D Fuel Fabrication & Reprocessing
A A Nuclear Other
1975
NUCLEAR FUEL CYCLE
A A Power Reactors
u u Fuel Fabrication & Reprocessing
A A Nuclear Other
i
1980
20'
0.01
NUCLEAR FUEL CYCLE
A A Power Reactors
D D Fuel Fabrication & Reprocessing
A A Nuclear Other
1 I
99.9999
• NUCLEAR FUEL CYCLE
O
s
LU
U
ff
LU
0.
LU
>
P
_l
O
u
99.99
99-9
99
0.01 1
ANNUAL DOSE EQUIVALENT (rem)
10
Figure B-6. Dose distributions for workers in the nuclear fuel cycle.
B-20
-------
Table B-4. Summary of mean annual and collective doses to
potentially exposed workers in the nuclear fuel cycle, 1960-1985
Occupation Mean annual dose equivalent (mrem)
1960 1965 1970 1915 1980 1985
Power Reactors 300 290 400 380 390 400
Fuel Fab. & Repro. 380 370 310 280 100 90
Other* 200 210 210 100 140 150
Total 320 300 320 320 360 380
3
Occupation Annual collective dose equivalent (10 person-rem)
1960 1965 1970 1975 1980 1985
Power Reactors
Fuel Fab. & Repro.
Other*
Total
0.1
0.9
0.3
1.3
0.2
1.8
0.7
2.7
3
2.6
0.8
6.4
20
3
1
24
52
1
1
54
73
1
1
76
*lncludes workers In uranium enrichment, nuclear waste management,
and uranium mills.
Its three subcategories from 1960 through 1985. The 1985 estimates In
Table B-3 were obtained from the log-log extrapolation of mean annual
dose and the number of workers according to their 1975-1980 trends (see
Figure 11). The mean annual dose Eor workers in the fuel fabrication
and reprocessing subcategory decreased substantially, while that in
power reactors remained essentially constant since 1970. The mean
annual dose Eor workers In the entire nuclear Euel cycle was essentially
constant prior to 1975; it increased after 1975 due to the dominant
contribution from power reactor workers.
D. Government
The dose distribution Eor workers in government in 1975 and 1980
was determined from nearly complete data from Federal agencies, except
B-21
-------
for the Veterans Administration, which was estimated from commercial
dosimetry data. The determination of reliable dose distributions for
the years 1960, 1965, and 1970, during which the government category
comprised the second largest category of workers, was also possible
because government data are quite complete for these years. That is,
the ABC (now DOE) and Navy, which both made annual exposure summaries
for these years, accounted for about 80% of potentially exposed workers
in government.
The 1960-1970 exposure data from the ABC had no dose range break-
down below 1 rem, so this portion of the dose distributions was recon-
structed with six dose ranges using the HLN model. The dose distribu-
tions for workers monitored by the Navy were constructed from the sum
of dose distributions for nuclear ship, shipyard, and medical groups,
as available. However, since the summaries for the medical group for
the period 1960-1975 gave only the collective dose and the number of
workers, we estimated their dose distributions from the trend of their
annual mean dose and their corresponding dose distributions in 1975 and
1980. There also were few dose ranges in the exposure data for person-
nel in nuclear ships and shipyards. Thus, the dose distributions for
these workers were reconstructed according to NRC dose-range format
using the HLN model.
The mean doses in 1960 for the Air Force and Army workers were
obtained from our previous report (Co80); those in 1970 were recalcu-
lated according to the trend of mean doses between 1960 and 1980 and
those in 1965 were Interpolated. The corresponding dose distributions
for workers in the Air Force and Army in 1960, 1965, and 1970 were then
constructed from the trends of their mean doses and their respective
dose distributions between 1975 and 1980. For lack of either supporting
or contrary evidence, the mean doses and the dose distributions for
workers in other agencies in 1960, 1965, and 1970 were assumed to be
similar to those in 1975.
B-22
-------
The dose distribution for all workers in government was obtained
from the weighted sum of the dose distributions oE the DOE/ABC, DOD,
and other Federal agencies. DOE/AEC and DOD combined have in effect
determined the worker dose distribution for the government category
since 1960. Figure B-7 gives the log-probability plots of this dis-
tribution in 1960, 1965, 1970, 1975, and 1980 and for its three sub-
categories in 1960, 1975, and 1980. The smooth curves to the data
points were fitted using the HLN distribution model.
Table B-5 gives the summary of the mean annual dose equivalent and
collective dose equivalent for workers in government and its three
Table B-5. summary of mean annual and collective doses to
potentially exposed workers in government, 1960-1985
Occupation
Dept. of Energy
Dept. of Defense
Other Agencies*
Total
Occupation
Dept. of Energy
Dept. of Defense
Other Agencies*
Total
Mean annual dose equivalent (rarera)
1960
200
80
30
150
Annual
1960
16
4
0.1
20
1965
180
260
30
210
collective
1965
24
24
0.2
48
1970
160
180
30
160
dose
1970
15
17
0
32
1975
140
100
30
110
equivalent
1975
11
9
.2 0.3
20
1980
80
50
20
60
1985
60
40
10
50
(10 person-rem)
1980
6
6
0.3
12
1985
5
5
0.2
10
*lncludes PHS (workers in various agencies and facilities covered by
the PHS Personnel Monitoring Program (see Table D-6 for details)),
NIH, NASA, NBS, and VA. Excludes MSHA (see Table 5 and Appendix C).
B-23
-------
1960
GOVERNMENT
A A Dept. of Energy
Q Q Dept. of Defense
A A Other Agencies
50
40
30
20
0.01
1975
GOVERNMENT
A A Dept. of Energy
a a Dept. of Defense
A A Other Agencies
GOVERNMENT
A Dept. of Energy
Q a Deal, of Detente
Other Agencies
99.9999
99.999
0 99.99
e
u
-------
subcategories from 1960 through 1985. The 1985 estimates were obtained
from the log-log extrapolation of mean annual dose and the number of
workers according to their 1975-1980 trends (see Figure 11). Both mean
dose and collective dose have decreased since 1965.
E. Miscellaneous
The dose distributions for workers in miscellaneous occupations
(education and transportation) in 1975 and 1980 were based primarily on
commercial data. The dose distributions for workers in education were
obtained from the weighted sum of the dose distributions corresponding
approximately to three groups identified as medical, allied health, and
sciences personnel. The dose distributions for transportation workers
were derived from commercial data, but with consideration of NEC studies
(NRC77a,77b). That is, the commercial dose distributions were adjusted
so that their mean doses would approximate the mean doses derived from
an NRC study (NRC77b).
The dose distributions for workers in education and transportation
for the years 1960, 1965, and 1970 were based on academic and transpor-
tation licensee data obtained in 1966-1971 ABC film badge studies
(AEC68a,68b,70,71,73).
Figure B-8 shows the log-probability plots of the dose distribu-
tions for all workers in miscellaneous occupations In 1960, 1965, 1970,
1975, and 1980 and for its two subgroups for 1960, 1975, and 1980. The
shapes of the dose distributions in 1975 and 1980 are clearly more
concave than those before 1975. However, the mean dose has remained
approximately constant at about 70 mrem since 1960.
Table B-6 shows the summary of mean annual dose and collective
dose equivalents for workers in miscellaneous occupations from 1960
through 1985. The 1985 estimates in Table B-6 were obtained from the
log-log extrapolation of mean annual dose and the number of workers
B-25
-------
99.999
99.99
99.9
1960
MISCELLANEOUS
A A Education
D n Transportation
201
0.01
99.999
99.99
99.9
1975
MISCELLANEOUS
A——A Education
Q n Transportation
1980
O—O MISCELLANEOUS
A A Education
O D Transportation
001
0.1 1
ANNUAL DOSE EQUIVALENT (rem)
10
Figure B-8. Dose distributions for workers in miscellaneous occupations.
B-26
-------
Table B-6. Summary oE mean annual and collective doses to potentially
exposed workers in education and transportation, 1960-1985
Occupation
Education
Transportation
Total*
Occupation
Education
Transportation
Total*
Mean annual dose equivalent (mrem)
1960
90
30
70
Annual
1960
0.9
0.2
1.1
1965
90
40
70
collective
1965
1.5
0.4
1.9
1970
110
40
80
dose
1970
2.5
0.9
3.4
1975
70
70
70
equivalent
1975
1.8
2.0
3.8
1980
60
70
70
1985
40
70
70
3
(10 person-rem)
1980
1.5
3.5
5.0
1985
1.2
5.3
6.5
*Excludes students, passenger aircraft crew members, and flight
attendants (see Table 5 and Appendix C).
according to their 1975-1980 trends (see Figure 11). The mean dose for
workers in education increased and in transportation decreased by about
a factor of two during this period, while the overall mean dose remained
roughly constant.
F- U.S. Total
The dose distribution for all potentially exposed workers (U.S.
Total) was estimated as the sum of the dose distributions of the five
categories used in this analysis. Figure B-9 gives the log-probability
plots of these dose distributions for all U.S. workers for 1960, 1965,
1970, 1975, and 1980 and for the five categories in 1960, 1975, and
1980. The display of these dose distributions on lognormal probability
paper clearly shows their departure from a lognormal distribution, which
would be a straight line. There were significant changes in the rela-
B-27
-------
- 1960
Medicine
-_ —- induitry
——— Nuclear Fuel Cycle
i —ii- — Government
»«• MiKellanooui
— U.S. Total
1975
Medldne
- —— - Industry
-——— Nuclear Fuel Cycle
• Miseellineoiii
• U.S. Total
99.999
20
0.01
- 1980
Modicum
— - Industry
Nuclur Fuel Cycle
^— — Government
Miicelleneoui
—— U.S. Total
0.1
99.999
CO 99.99
oc
111
g
u.
O
1-
UJ
U
K
3
U
99.9
99
90
80
70
60
SO
40
30
20
0.01
U.S. TOTAL
O 1980
A 1975
• 1970
D 1965
A 1960
0.1 1
ANNUAL DOSE EQUIVALENT (rem)
10
Figure B-9. Dose distributions for all workers.
B-28
-------
tlonships of the distributions for the five categories for the period
1960 to 1980. The dose distribution for workers in medicine was very
close to that for all workers in 1960, but departed considerably from
it in 1980; that for industry was quite different from that for all
workers in 1960, but became very close to it in 1980; and those for the
nuclear fuel cycle and the miscellaneous workers remained quite differ-
ent from that for all workers for the entire period from 1960 to 1980,
while that for government workers was reasonably similar except for in
1980.
The data for the dose distributions for all workers for 1960,
1965, 1970, 1975, and 1980 were fitted very well using the HLN model,
as shown in Figure B-9. The bottom graph clearly demonstrates the
increasing curvature of the distributions since 1960. This is inter-
preted to mean that there have been increasing efforts to reduce higher
exposures since 1960.
In Tables B-7 and B-8, we summarize the mean annual dose equivalent
and the annual collective dose to workers potentially exposed to radia-
tion by subcategory, category, and for all workers, for the period 1960
to 1985. The collective dose equivalents in Table B-8 were determined
from the numbers of potentially exposed workers given in Table A-ll and
the mean annual dose equivalents given in Table B-7 before rounding off
these latter values. The 1985 estimates for the entire work force in
Tables B-7 and B-8 agree well with those obtained by the log-log extra-
polation of the mean annual dose and the total number of workers from
their corresponding 1975-1980 trend (see Figure 11). The mean annual
dose in 1960 and 1965 was approximately constant at 180 mrem, but
decreased by about 30 mrem every five years between 1965 and 1975.
After 1975, the mean annual dose decreased more slowly to a projected
dose of 105 mrem in 1985. The total collective dose increased by about
25,000 person-reras every five years after 1975, while it fluctuated
around 120,000 persons-rents between 1965 and 1975.
B-29
-------
Table B-7. Summary of mean annual dose to potentially
exposed workers, 1960-1985
Occupation
Medicine
Dentistry
Private practice
Hospital
Other
Industry
Radiography
Manufac. & distr.
Other users
Nuclear Fuel Cycle
Power reactors
Fuel fab. & repro.
Other
Government
Dept. of Energy
Dept. of Defense
Other agencies ( c)
Miscellaneous
Education
Transportation
All Workers
Mean annual dose
1960
190
110
280
400
50
230
630
320
210
320
300
380
200
150
200
80
30
70
90
30
180
1965
160
80
230
300
50
240
490
360
210
300
290
370
210
210
180
260
30
70
90
40
180
1970
120
60
180
230
50
220
310
360
200
320
400
310
210
160
160
180
30
80
110
40
150
equivalent (mrem)
1975
100
40
140
190
50
140
280
220
120
320
380
280
100
110
140
100
30
70
70
70
120
1980
70
20
100
140
50
120
290
110
110
360
390
100
140
60
80
50
20
70
60
70
110
1985
50
10
80
100
60
110
300
80
100
380
400
90
150
50
60
40
10
70
40
70
105
(^Veterinary medicine, chiropractic medicine, and podiatry.
(b)uranium enrichment, nuclear waste management, and uranium mills.
(C)PHS (workers in various agencies and facilities covered by
the PHS Personnel Monitoring Program (see Table D-6 for details)),
NIH, NASA, NBS, and VA.
B-30
-------
Table B-8. summary of annual collective dose to potentially
exposed workers, 1960-1985
occuuatian Annual collective
1960
Medicine
Dentistry
Private practice
Hospital
Other
Subtotal
Industry
Radiography
Manufac. & distr.
Other users
subtotal
Nuclear fuel cycle
Power reactors ,
Fuel fab. & repro.
Other
subtotal
Government
Dept. of Energy
Dept. of Defense
Other agencies^)
Subtotal
Miscellaneous
Education
Transportation
Subtotal
Total
15
31
11
1
58
0.1
0.6
10
11
0.1
0.9
0.3
1
16
4
0.1
20
0.9
0.2
1
91
1965
12
26
15
1
54
3
2
13
18
0.2
1.8
0.7
3
24
24
0.2
48
1.5
0.4
2
125
3
dose equivalent (10 nersnn-roml
1970
10
22
17
1
50
4
3
20
27
3
2.6
0.8
6
15
17
0.2
32
2.5
0.9
3
118
1975
8
18
18
2
46
5
4
20
29
20
3
1
24
11
9
0.3
20
1.8
2.0
4
123
1980
6
16
17
2
41
8
3
27
38
52
1
1
54
6
6
0.3
12
1.5
3.5
5
150
1985
3
14
16
3
36
10
3
34
47
73
1
1
76
5
5
0.2
10
1.2
5.3
6
175
^Veterinary medicine, chiropractic medicine, and podiatry.
(b)uranium enrichment, nuclear waste management, and uranium mills.
te^PHS (workers in various agencies and facilities covered by the PHS
Personnel Monitoring Program (see Table D-6 for details)), NIH,
NASA, MBS, and VA.
B-31
-------
III. DISTRIBUTIONS OF COLLECTIVE DOSES
One approach for calculating the value of collective dose is the
midpoint method. This method entails multiplying the number of individ-
uals in a given dose range by the midpoint value of that range and then
summing this product for all dose ranges. Because of the large span of
dose ranges for much of the published exposure data, this method is not
very precise and results in an overestimate of the actual collective
dose.
To obtain the best and most consistent estimates of 1975 and 1980
collective doses, collective dose distributions for each of the major
categories were derived from the first moments of the hybrid lognormal
(HLN) fits to the dose data (see Appendix F). The distributions of col-
lective dose derived from either the sum of the collective dose distri-
butions for the major categories or from the first moment distribution
of exposure data for the entire work force were consistent. We note
that, in general, the sum of five separate hybrid lognormal distribu-
tions does not assure a composite distribution that is well described
by a hybrid lognormal distribution. Nevertheless, the difference be-
tween elements of collective dose distributions calculated from these
two methods was less than 10 percent. Similarly, the sum of the dis-
tributions of collective doses in subcategories differed only slightly
from the first moment distribution of exposure data for the entire
category.
Estimates of collective dose in the higher dose ranges are quite
sensitive to small changes in the number of workers exposed. Because
of statistical fluctuations in these data, we adjusted the calculated
first moments to obtain consistency with the original data. For ex-
ample, where there was a significant difference between the number of
workers and the value from the HLN fit, it was sometimes necessary to
reassign some collective dose (i.e., first moment) to an adjacent range
to assure that the mean dose (collective dose divided by number of
B-32
-------
workers in that range) fell in the appropriate range. These adjustments
to assign collective dose to adjacent ranges were minor and are reflect-
ed in Figures 4 and 5. We also separately analyzed the collective dose
distributions for males and females in the five categories and for the
entire work force (see Appendix C).
Figure B-10 gives the log-probability plots of the distributions
of collective dose for all male, all female, and combined for all male
and female workers. The smooth curves give the HLN first moment distri-
butions calculated from the corresponding dose distributions for male,
female, and all workers. The collective dose data points obtained in
each dose range by summing the contributions from the five categories
separately for males and females lie very close to the corresponding
calculated curves.
Figure B-ll shows the log probability plots of the distribution of
collective dose for all workers in 1960, 1965, 1970, 1975, and 1980 and
the five categories in 1960, 1975, and 1980. These were calculated
from the first moments of the HLN fits of the dose distributions (see
Appendix F).
The distribution of collective dose for the nuclear fuel cycle has
the most concave curvature among the five categories since 1960. in
1960, the distribution of collective dose for medical workers is com-
prised of relatively higher worker doses than that for all workers;
while in 1975 the situation is reversed. The distribution of collec-
tive dose for government workers alone is always comprised of lower
doses than for all workers.
The distribution of collective dose for all workers shows little
change for doses below 1 rem since 1960, but a sizable change for doses
above 1 rem. This can be seen in Figure B-ll. The fractions of collec-
tive dose above 1.5 rems were 0.53, 0.53, 0.44, 0.46, and 0.40, in 1960,
1965, 1970, 1975, and 1980, respectively. These values correspond to
B-33
-------
LLJ
W
O
Q
LU
8
UJ
O
DC
01
Q.
01
O
99.99
99.9
99
95
90
80
70
60
50
40
30
20
10
5
I
HLN first moment distribution calculated
from the U.S. total worker dose distribution.
— — — Female
— • —• Male
Both
A sum of collective dose distributions for
five categories (see text).
V Female
A Male
O Both
0.01 0.1 1
ANNUAL DOSE EQUIVALENT (rem)
Figure B-10. Collective dose distributions for males, females,
and all workers, 1980.
10
B-34
-------
.- Medicine
- —— - Industry
———— Nuclear Fuel Cycle
•™" ~ «"» Government
Miscellaneous
- U.S. Total
_•-_._ Medicine
— — — —• Industry
—— — Nuclear Fuel Cycle
—— — Government
•••• Miscellaneous
•' U, S. Total
—— Nuclear Fuel Cycle
1975
1970
0.01
0.1 1
ANNUAL DOSE EQUIVALENT (rem)
Figure B-11. Collective dose distributions for all workers.
B-35
-------
the "collective close distribution ratio," MR, defined by the united
Nations Scientific Committee on the Effects of Atomic Radiation
(UNSCERR). The latest UNSCEAR report (UNSCEAR82) states that normal
values of VSR lie between 0.05 to 0.5. The values of MR for U.S. workers
fall within this range since 1970 and show a decreasing trend for the
1960-1980 period. Compared to the decrease in MR values between 1960
and 1980, the fractions of collective dose above 5 rems showed a sharper
decrease as follows: 0.25 in 1960, 0.31 in 1965, 0.15 in 1970, 0.1 in
1975, and 0.05 in 1980. Also, the median for the collective dose
distributions decreased from 1.7 rems in 1960 to 1.1 rems in 1980.
IV. AGE DISTRIBUTIONS
A. Distribution of Worker Ages
Age distributions of workers in the five categories and for all
workers were estimated from commercial dosimetry data for males and
females in both 1975 and 1980. We used the Johnson S distribution
D
to examine the characteristics of age distributions for each worker
group in the commercial data (see Appendix F). We then used these to
construct age distributions in each subcategory of the five categories
of workers. The age distribution for each category was obtained by
combining the age distributions of its subcategories. Finally, the age
distribution for the entire work force was obtained from the weighted
sum of distributions for the five categories.
Figure B-12 shows the age distributions for potentially exposed
male and female workers and the age distributions for male and female
workers of the entire U.S. labor force in 1975 and 1980 using a Johnson
S probability plot (see Appendix F). The horizontal axis is the
D
quantity ln[(y-a)/(b-y)] where y is worker age (years). The four curves
for the U.S. labor force show the age distributions in 1975 and 1980
for males and females tightly grouped together. The age distribution
B-36
-------
CO
DC
LU
*
cc
o
z
UJ
u
QC
LU
a.
LU
o
99.9
99
95
90
80
70
60
50
40
30
20
10
5
1 1 1—r
U.S. Potentially Exposed Workers:
- — — — — Female 1975
Female 1980
Male 1975
Male 1980
T 1 T
U.S. Total Labor Force:
__ _ _ — Female 1975
—.— — Female 1980
• Male 1975
Male 1980
20
25 30 35 40 45
AGE (YEARS)
50 55 60 65
Figure B-12. Male and female age distributions for potentially
exposed workers and age distributions for the
U.S. labor force, 1975 and 1980.
B-37
-------
for the entire U.S. labor force in 1980 was slightly younger than that
for 1975. The age distribution for female workers was slightly younger
than that for male workers both in 1975 and 1980.
The age distributions for workers potentially exposed to radiation
were significantly different from those for all workers in the U.S.
labor force. Potentially exposed workers were slightly older in 1980
than those in 1975 for both sexes. The ages of potentially exposed
female workers were considerably younger than that of potentially
exposed male workers in both 1975 and 1980.
Figure B-13 shows the combined male and female age distributions
for the entire U.S. labor force and all potentially exposed workers in
1975 and 1980 and for the U.S. population in 1980. The age distribution
of the U.S. population in 1980 was the broadest with about 33% and 12%
of persons being younger and older than 20 and 65 years of age, respec-
tively. The distribution of the potentially exposed workers in 1980
was the narrowest with about 5% and 0.5% of workers being younger and
older than 20 and 65 years of age, respectively. The age distribution
of the entire U.S. labor force in 1980 was between these with about 10%
and 3% of workers being younger and older than 20 and 65 years of age,
respectively. We conclude that potentially exposed workers have a
quite different age distribution than that of the entire U.S. labor
force.
B. Distribution of Collective Poses by worker Age
The distributions of collective dose by worker's age were estimated
for 1975 and 1980 from commercial data for males and females for each
of the five categories. We examined the characteristics of these
distributions for each worker group in the commercial data. We then
estimated the collective dose distribution in each subcategory from the
weighted sum of these collective dose distributions.
B-38
-------
99.9
cc
UJ
*
CC
i
LL.
O
ui
U
CC
UJ
a.
UJ
U
U.S. Potentially Exposed
Workers 1975
U.S. Potentially Exposed
Workers 1980
U.S. Total Labor Force 1975
U.S. Total Labor Force 1980
U.S. Total Population 1980
35 40 45 50 55 60 65
AGE (YEARS)
Figure B-13. Age distributions for potentially exposed workers and
U.S. labor force, 1975 and 1980, and U.S. population, 1980.
B-39
-------
99.9
01
c/>
§
01
8
DC
O
CO
QC
UJ
*
QC
i
u.
O
I-
iii
O
or
UJ
O.
UJ
S
O
O
99 -
O Workers in 1975
— —A Collective Dose in 1975
Workers in 1980
—A Collective Dose in 1980
20
30 35 40 45 50 55 60
AGE (YEARS)
Figure B-14. Age distributions for potentially exposed workers
and of collective dose, 1975 and 1980.
B-40
-------
Figure B-14 shows the distributions of age of potentially exposed
workers and of their collective dose in 1915 and 1980. The collective
dose-weighted median age of workers is slightly larger than the median age
of workers in 1980, while the reverse is true for 1975. The fraction of
workers below 25 years is slightly greater than the fraction of collective
dose delivered to workers below 25 years both in 1975 and 1980. The frac-
tion of workers above 45 years is slightly greater than the fraction of
collective dose delivered to workers above 45 years both in 1975 and 1980.
From these observations we conclude that the distributions of collective
dose by worker age are slightly narrower than the distributions of worker
age in both 1975 and 1980.
C. Summary
The age distribution of all U.S. workers is narrower than that of the
entire U.S. population, as expected, since relatively few persons work
before age 18 or after age 65. The age distribution of potentially exposed
workers was found to be narrower than that of all U.S. workers. This means
that potentially exposed workers, on the average, start working later and
leave these jobs earlier than the average U.S. worker.
Table B-9 gives the summary of mean and median values of the age of
potentially exposed workers and of collective dose-weighted age for the
entire work force and five categories for male, female, and both sexes in
1980. In general, the mean age of workers was two to three years greater
than their median age.
B-41
-------
Table B-9. Estimated mean and median age of workers
potentially exposed to radiation, by sex, 1980
Mean aqe (vr)
Occupation
Medicine
Industry
Nuclear Fuel Cycle
Government
Miscellaneous
Total
Potentially^
Both sexes
31
35
35
34
33
33
exposed
Male
36
35
36
35
35
35
workers
Female
29
35
30
32
32
30
Median aqe
Occupation
Medicine
Industry
Nuclear Fuel Cycle
Government
Miscellaneous
Total
Potentially
Both sexes
29
32
33
32
29
31
exposed
Male
34
32
33
33
32
33
workers
Female
27
32
28
30
28
28
Collective dose
Both sexes
33
33
34
36
34
34
(vr)
Male
36
33
34
37
34
34
Female
30
35
29
33
33
31
Collective dose
Both sexes
30
31
32
34
30
31
Male
34
31
32
35
32
32
Female
28
32
27
30
29
29
B-42
-------
APPENDIX C
ADDITIONAL INFORMATION AND RESULTS FOR 1980
-------
CONTENTS
Page
I. INTRODUCTION c_5
II. ADDITIONAL GROUPS OF INDIVIDUALS POTENTIALLY EXPOSED TO
RADIATION c_5
A. Summary of Principal Results for 1980 C-5
1. Whole Body Radiation C-5
2. Radon Decay Products C-6
3. Cosmic Radiation Exposure C-6
B. Underground Miners C-7
1. Number of Underground Uranium Miners C-7
2. Radon Decay Product Exposure of
Underground Uranium Miners C-7
3. Gamma-ray Exposure of Underground Uranium Miners. . . . C-10
4. Radon Decay Product and Gamma-ray Exposure
of Nonuranium Miners C-ll
C. Other Worker Groups C-12
D. Projection for 1985 C-13
III. EXTREMITY EXPOSURES IN 1980 C-13
A. Number of Exposed Workers C-13
B. Extremity Doses C-14
IV. SUMMARY OF WORKER EXPOSURE BY OCCUPATION, SEX, AGE,
AND DOSE RANGE C-16
V. PERSONNEL DOSIMETRY PERFORMANCE C-16
A. Introduction c~16
»
B. Dosimeter Performance c~23
VI. COMPARISON OF DOSES TO FULL-TIME WORKERS AND DOSES
TO COMBINED PART- AND FULL-TIME WORKERS C-24
C-3
-------
CONTENTS (Continued)
TABLES
Page
C-l. Crude estimates of radiation exposure to worker
extremities, 1980 C-15
C-2. Estimated number of potentially exposed workers by dose
range, occupation, and sex, 1980 C-17
C-3. Estimated collective dose to exposed workers by dose range,
occupation, and sex, 1980 C-18
C-4. Estimated number of potentially exposed workers by age,
occupation, and sex, 1980 C-19
C-5. Estimated collective dose to exposed workers by age,
occupation, and sex, 1980 C-20
C-6. Mean annual dose equivalent to potentially exposed workers
by occupation, sex, and age, 1980 C-21
C-7. Mean annual dose equivalent to potentially exposed workers
by occupation and age, 1980 C-21
C-8. Mean annual dose equivalent to measurably exposed workers
by occupation, sex, and age, 1980 C-22
C-9. Mean annual dose equivalent to measurably exposed workers
by occupation and age, 1980 C-22
C-10. Mean annual dose equivalent to full-time workers and to
combined part- and full-time workers C-25
FIGURES
C-l. Log probability plots of annual exposure to radon decay
products for potentially exposed and measurably exposed
underground uranium miners, 1980 C-9
C-4
-------
APPENDIX C
ADDITIONAL INFORMATION AND RESULTS FOR 1980
I. INTRODUCTION
This appendix summarizes 1980 data on exposure of some additional
groups of individuals, extremity exposures, and numbers of U.S. workers
and their collective doses in dose and age ranges by sex and by cate-
gory. In addition, we summarize some results of recent testing of per-
sonnel dosimetry performance and make a cursory comparison of doses to
full-time workers with doses to combined part- and full-time workers.
II. ADDITIONAL GROUPS OF INDIVIDUALS POTENTIALLY EXPOSED TO RADIATION
A. Summary of Principal Results for 1980
Table 5 in Chapter IV summarizes our results for groups of persons
potentially exposed to radiation not included in the national summary
for 1980 in Table 4. We summarize the basis for these results below.
1. Whole Body Radiation
We estimate about 0.27 million persons were potentially exposed to
occupational sources of radiation in 1980 as flight personnel or miners,
as visitors to DOE facilities, or as students; about 55% of these are
estimated to have received a measurable dose. The mean annual dose
C-5
-------
equivalent was 90 mrera for all such persons potentially exposed and
160 mrera for those measurably exposed. The total collective dose equi-
valent to these individuals was about 23,700 person-rents, of which 70%
is for flight personnel. Students potentially received the second
largest collective dose, about 3300 person-reras. Underground uranium
miners exhibited the highest mean annual dose and visitors to DOB
facilities had the smallest.
2. Radon Decay Products
The roughly 18,000 potentially exposed underground miners were
estimated to have received a mean annual exposure of 0.4 WLM in 1980
and a collective exposure of about 7,500 person-WLM from exposure to
radon decay products. Nearly 60% of these miners were estimated to
have a mean measurable annual exposure of 0.7 WLM. About 90% of the
collective exposure was incurred by about 13,500 uranium miners with a
mean annual exposure of 0.5 WLM. Their mean measurable annual exposure
was 0.9 WLM.
3. Cosmic Radiation Exposure
Cosmic radiation is not usually considered in the assessment of
occupational exposure, because it is simply a part of natural back-
ground radiation to which everyone is involuntarily exposed whether on
the job or elsewhere. However, for flight personnel, who spend many
working hours at high altitudes, the contribution from cosmic radiation
exposure is higher than and is a significant addition to normal expo-
sure to background radiation. In 1980, there were about 97,000 flight
crew members and attendants, who were estimated to have a mean incremen-
tal annual dose of 170 mrem and a collective dose of about 16,500 per-
son-rems from cosmic radiation exposure. Their collective dose from
transport of radioactive materials was estimated to be only about 200
person-rems.
C-6
-------
B. Underground Miners
1. Number of Underground Uranium Miners
The U.S. uranium mining industry has experienced marked changes in
activity since 1960. Shipments of uranium mine ore dropped rapidly from
8 million short tons in 1960 to half that in 1965. During the next ten
years ore shipments made a gradual recovery, approaching the 1960 level
by 1975. This gradual recovery was followed by a very rapid increase
in shipments that more than doubled by 1979. but then dramatically
decreased after 1979 (DOC81, DOE83).
The number of miners has closely paralleled the quantity of uranium
shipped. We estimated there were 7.000 underground uranium miners in
1960, about 4,000 in 1965. about 5,000 in 1970, and about 6,000 in 1975,
from modeling historical data reported by MSHA (Pa84) and others (DOC80,
81). The reported number of miners in 1980 was 13,484, decreasing from
a peak of 14,578 in 1979. We previously reported 3,344 underground ura-
nium miners for 1975, but this number represented only those miners
estimated to be exposed above 0.01 WLM (Co80); our estimate for the num-
ber of all underground uranium miners in 1975, regardless of exposure
level, is about 6,000.
2. Radon Decay Product Exposure of Underground Uranium Miners
The exposure of U.S. underground uranium miners to radon decay
products was correlated with an increase in their lung cancer in the
1960's (FRC67). In 1971, the Environmental Protection Agency (EPA71)
adopted the 4 WLM per annum standard approved on a trial basis in 1969
(FRC69) in place of the earlier 12 WLM per annum standard that had been
recommended by the Federal Radiation Council in 1967. A marked reduc-
tion in exposures was achieved during the early 1970's. However, accu-
rate exposure records for U.S. uranium miners were not available until
the mid-1970's.
C-7
-------
We obtained statistics on the exposure of underground uranium
miners to radon decay products from MSHA for the period 1974 to 1981
and from the Atomic Industrial Forum (AIF) for the period 1976 to 1980.
The MSHA statistics for the period after 1980 are reported in exposure
ranges of 0-1 WLM. 1-2 WLM, 2-3 WLM, 3-4 WLM, and more than 4 WLM, and
include a range of less-than-measurable exposure. These annual expo-
sures of underground uranium miners show a normal distribution above
1 WLM. We obtained additional exposure detail below 1 WLM (exposure
range widths of 0.1 WLM) for the 1980 data (S184) to examine the dis-
tribution of the lowest exposures. HLN modeling of these data confirmed
our presumption of lognormal characteristics in exposure ranges below 1
WLM. '
Figure C-l shows log probability plots of the annual exposure of
underground uranium miners to radon decay products in 1980. The data
for all miners and for measurably exposed miners fit a HLN distribution
well. From these HLN data fits, we calculated mean annual exposures
of 0.5 WLM and 0.9 WLM for all and measurably exposed underground
uranium miners, respectively, in 1980.
The dotted curve in Figure C-l shows the collective exposure
distribution (in person-WLM) calculated from the first moment distribu-
tion of the HLN-fitted annual exposure distribution of underground
uranium miners. The exposure distributions of all miners, measurably
exposed miners, and the collective exposure distribution all exhibit a
pronounced curvature, as shown in Figure C-l. This curvature indicates
the presence of active efforts to limit exposure of miners as they
approach an accumulation of 4 WLM.
Since exposure data for other years do not contain dose distribu-
tion details below 1 WLM, there is uncertainty in the data fits made to
the HLN model. However, by comparing the annual exposure distributions
above 1 WLM for the years 1974 through 1981, we found that the fraction
of underground uranium miners exposed to more than 2 WLM has apparently
C-8
-------
cc
V)
2
UJ
u
UJ
O
o
cc
o
co
cc
HI
Ul
u
cc
UJ
0.
UJ
5
U
99.99
99.9
99
95
90
80
70
60
50
40
30
20
10
5
0.01
EXPOSURE TO RADON DECAY PRODUCTS
0.1 1
ANNUAL EXPOSURE (WLM)
Figure C-1. Log probability plots of annual exposure to radon decay
products for potentially exposed and measurably exposed
underground uranium miners, 1980.
10
C-9
-------
been decreasing slowly. The median annual exposure of measurably
exposed miners decreased from 0.8 WLM in 1975 to 0.1 WLM in 1980. The
mean annual exposure for measurably exposed miners was estimated to
decrease from 1.1 WLM in 1975 to 0.9 WLM in 1980.
The AIF statistics on the annual exposure of underground uranium
miners to radon decay products are valuable, since they contain detailed
data on type of occupation and on the number of annual working hours.
About 50% of these miners worked in production and development, about
20% were in service work (motorman, haulage crews, etc.), and the rest
were in maintenance and other work (engineers, supervisors, etc.).
Production and development miners had the largest annual exposure,
followed by those in service work.
Our analysis appears to indicate that the AIF data only include
measurably exposed miners, since the annual exposure distributions above
1 WLM agree with MSHA distributions for measurably exposed miners.
Using HLN fits to the AIF data, we estimated that underground uranium
miners who worked 1500 hours or more in 1980 had a mean annual exposure
of 1.3 WLM, compared to a mean annual exposure of 1.0 WLM for all under-
ground uranium miners.
In summary, we estimate that the mean annual exposure of all under-
ground uranium miners was 0.6 WLM in 1975 and 0.5 WLM in 1980; for meas-
urably exposed underground uranium miners, the mean annual exposure was
l.l WLM in 1975 and 0.9 WLM in 1980.
3. Gamma-ray Exposure of Underground Uranium Miners
Underground uranium miners are also exposed to significant levels
of gamma radiation. We have only limited data on gamma ray exposure of
workers in uranium mine operations in 1980; these data are assumed to
be only roughly indicative of such exposure. The mean dose to 83 meas-
urably exposed workers was about 160 mrem per quarter and about 350 mrem
C-10
-------
per year, respectively, for workers monitored for one quarter and for
one year. Assuming an average annual working time of 1600 hours, the
mean doses of 160 mrem/quarter and 350 mrem/year correspond to gamma
exposure rates of approximately 0.2 milliroentgen/hour (mR/h) and 0.4
milliroentgen/hour (mR/h), respectively.
MSHA mine inspectors have made limited measurements of the distri-
bution of gamma exposure rates. On a given day, the set of data for
various locations at a mine exhibit a lognormal distribution. The
median exposure rates at different mines ranged from 0.04 mR/h to 2.5
mR/h; the geometric mean is about 0.3 mR/h. As the exposure rate of
2.5 mR/h is believed to correspond to only a very few mines with atypi-
cal exposures, the typical exposure rate may be somewhat less than 0.3
mR/h. However, it is consistent with the calculated exposure rates for
the above monitored miners.
From the above, we estimate a mean annual dose equivalent of 200
mrem to all miners and 350 mrem to measurably exposed miners in 1980.
However, since these values are based upon very limited data, we pre-
sent them only as a rough measure of the magnitude of gamma exposure of
miners.
4. Radon Decay Product and Gamma-ray Exposure of Nonuranium Miners
Nonuranium miners include workers in other metal, nonmetallic
mineral, coal, and stone mines. Those potentially exposed to signifi-
cant (compared to background) levels of radon decay products and gamma
radiation are mostly workers in underground metal mines. The number of
nonuranium metal mining workers has generally ranged between 90,000 and
100,000 since 1960 (DoC81). In 1980. about 4% of workers at nonuranium
metal mines were assessed for exposure to radon decay products (S184),
because these mines contained concentrations of radon decay products in
excess of 0.3 WL. We assume that this same fraction was also similarly
exposed to elevated levels of gamma radiation. This leads to an esti-
C-ll
-------
mate of about 4,200 nonuranium miners (compared with 13,500 uranium
miners) exposed to radon decay products and gamma radiation. Based on
limited data, we estimated the mean annual radon decay product exposure
to be 0.2 and 0.3 WLM for these potentially and measurably exposed
miners, respectively, and the mean annual gamma-ray dose to be 150 and
220 mrem for potentially and measurably exposed miners. We have not
made estimates for the much larger group of miners exponed to less than
0.3 WL.
C. Other Worker Groups
This section briefly describes radiation exposures of visitors to
DOB facilities, students, flight crew personnel, and flight attendants.
Since 1977 about 50% of the DOE and DOE-contractor monitoring data
has been for visitors; before that time, about 40% was for visitors
(DOE76-82). The mean annual dose to DOE visitors has been approximately
10 mrem since 1974 (DOE76-82). The number of DOE visitors is estimated
to be about 90,000 in 1985 (see Table A-ll), based on the assumption
that the fraction of DOE monitoring data representing visitors remains
at 50%.
The number of students in U.S. colleges doubled during the period
1965 to 1975, but has remained almost constant since 1975 (DOC81). The
method for estimating the number of students potentially exposed to
radiation was described in Appendix A. We estimated approximately
26,000 potentially exposed students in 1960; 35,000 in 1965; 49,000 in
1970; 64,000 in 1975; and 67,000 in 1980. Since 1965, these estimates
of potentially exposed students corresponded to about 0.6% of all U.S.
college students. We estimated that about 68,000 students will be
potentially exposed in 1985. Estimated doses to students were obtained
from commercial dosimetry data.
The number of flight crew personnel doubled during the period 1960
to 1970, while the number of flight attendants tripled (DOC81). The
C-12
-------
number of flight crew personnel was almost constant from 1970 to 1975
(DOC81), but doubled during the period 1975 to 1980. Flight attendants
increased about 15% from 1970 to 1975 (DOC81) and increased about one-
and-a-half times from 1975 to 1980. We have estimated that flight crews
will number about 47,000 persons in 1985, and flight attendants about
82,000 persons. The overwhelming source of exposure of these persons
is cosmic radiation, which averages about 170 mrem per year over that
normally received at the earth's surface (1000 hours/yr x .23 mrem/h x
75% flying time at 9 km altitude). The estimated dose contribution
from radioactive materials is small, averaging only 1 mrem and 6 mrem,
respectively, to 50% of flight attendants and crew members (NRC77b).
D. Projection for 1985
The number of potentially exposed persons in these additional
groups (miners, flight crews and attendants, DOB visitors, and students)
is estimated to be about 0.3 million in 1985. This is about 18% of the
estimated 1.64 million potentially exposed workers in the entire work
force in 1985 (see Table A-ll).
III. RXTRKMITY EXPOSURES IN 1980
A. Number of Exposed Workers
In most cases there were little or no data available for exposed
extremities. However, based on some limited records, we can estimate
the number of workers receiving exposure of extremities per thousand
workers potentially exposed to radiation. These values can then be
used to extrapolate the number of workers receiving extremity exposures
out of the total number of potentially exposed workers.
in 1980, there were about 21.000 records of extremity exposures by
age and sex in our commercial dosimetry data. This number of records
C-13
-------
was about four times larger than that available in 1975. The number of
records with age and sex information increased 10% for males and 17%
for females. However, the distribution of the numbers of extremity
records per thousand workers potentially exposed (the specific number
exposed) for the worker groups in the commercial data for 1980 were
very similar to those for 1975. Therefore, we assumed that these data
would be suitable for estimating extremity exposures in the entire work
force.
The number of workers potentially receiving extremity exposures per
thousand potentially exposed workers was estimated to be about 50 for
the total work force (60 for male workers and 30 for female workers) and
40 for medicine, 80 for industry, 20 for the nuclear fuel cycle, and 50
Tor the government and miscellaneous occupations. Among subcategories
of workers in medicine, the number of workers potentially receiving
extremity exposures per thousand workers ranged from about 1 for dentis-
try to about 100 for hospitals.
B. Extremity Doses
The mean annual extremity dose for those workers potentially
receiving extremity exposures was estimated to be about 0.4 rem; for
males, about 0.5 rem, and for females, about 0.3 rem; for workers in
medicine, 0.4 rem; for those in industry, 0.3 rem; for nuclear fuel
cycle workers, 0.8 rem; for government workers, 0.3 rem; and for workers
in miscellaneous occupations, 0.25 rem. The mean annual extremity dose
among subcategories of workers in medicine ranged from about 0.02 rem
for those in dentistry to about 0.6 rem for those in private practice.
The subcategories of workers in industrial radiography, manufacturing
and distribution, and fuel fabrication and reprocessing all had mean
annual extremity doses greater than 1 rem.
Our estimates of numbers of workers and mean annual dose
equivalents for exposure of extremities are summarized in Table C-l.
C-14
-------
Table C-l. Crude estimates of radiation exposure to worker extremities, 1980
Dose to extremities
Occupational
category
Medicine
Dentistry
Private Practice
Hospital
Other (°)
Industry
Radiography
Manufac. & Distr.
Other Users
Nuclear Fuel Cycle
Power Reactors
Fuel Fab. & Repro.
Other W>
Government
Dept. of Energy
Dept. of Defense
Other Agencies te)
Miscellaneous
Education
Transportation
All U.S. Workers
Number
All
21,600
300
8,800
12,200
300
24,200
500
2,700
21,000
2,800
1,600
1,000
200
11,400
5,000
4,100
2,300
3,800
2,800
1,000
63.800
of worker sta)
Exposed*)
15,100
60
6,200
8,700
140
11,500
350
1,700
9,450
1,900
1,060
700
140
4.800
2,000
1,800
1,000
1,600
1,400
200
34.900
Mean annual dose
equivalent (mrem)
All Exposed*)
400
20
640
240
280
340
1,400 2
1,630 2
150
800 1
750 1
1,900 2
500
280
300
340
130
180
250
10
370
570
100
900
330
570
710
,000
,590
330
,680
,130
,710
710
670
750
780
300
440
500
30
68£
Collective dose
equivalent
(person-rem)
8,600
6
5,600
2,900
80
8,200
700
4,400
3,100
3,200
1,200
1,900
100
3,200
1,500
1,400
300
700
700
5
23.900
'^Estimated numbers of workers are generally rounded to the nearest 100, mean doses
to the nearest 10 mrem, and collective doses to the nearest 100 person-rems.
^Workers who received a measurable dose in any monitoring period.
(^Veterinary medicine, chiropractic medicine, and podiatry.
^Uranium enrichment, nuclear waste management, and uranium mills.
(e)pHS (workers in various agencies and facilities covered by the PHS Personnel
Monitoring Program—see Table D-6 for details), NIH, NASA, NBS, and VA.
C-15
-------
IV. SUMMARY OF WORKER EXPOSURE BY OCCUPATION, SEX, AGE, AND DOSE RANGE
The estimated numbers of workers in 1980 and the collective doses
to workers in various dose and age ranges by sex and occupational cate-
gory are shown in Tables C-2 through C-5 (see also Figures 4 through 7).
The values shown in Tables C-2 through C-5 are given to a larger
number of significant figures than their inherent accuracy warrants for
consistency and completeness only.
Tables C-6 and C-7 show t;ho moan annual dose equivalent in age
ranges by occupational category for male and female workers; Tables C-8
and C-9 show the mean measurable annual done equivalent.
V. PERSONNEL DOSIMETRY PERFORMANCE
A. Introduction
The occupational exposure of persons can involve partial or whole
body irradiation from sources of ionizing radiation that may be external
or internal to the body. However, the major objective of this study
has been to summarize occupational exposure to external penetrating
radiation in terms of the readings of personnel dosimeters. One of the
uncertainties that affects the accuracy of our estimates is the perform-
ance of personnel dosimeters.
Most doses to workers from penetrating radiation result primarily
from high and low energy photons in the form of gamma rays and x rays.
Therefore, we particularly examine the uncertainties in the measurement
of doses from these types of radiation.
Recent studies of personnel dosiraetry performance indicated fair
performance, but with considerable room for improvement (P183). For
C-16
-------
Table c-2. Estimated number of potentially exposed workers
by dose range, occupation, and sex, 1980
0
1
(vrf
-J
Annual
dose
equivalent
(rem)
0-MD
MD-0 . 1
0.1-0.25
0.25-0.5
0.5-1
1-2
2-3
3-4
4-5
5-8
8-12
12+
Number of
workers
Nuclear
Total
Male
322398
248041
54280
30901
29021
20991
8158
3389
1662
716
91
2
Female
336987
206750
32547
16325
7965
3245
721
221
102
83
17
0
Medicine
Male Female
75460 231046
59079 146890
12296 23782
6627 11657
4422 5902
2438 2191
734 587
279 188
117 100
128 77
24 16
0 0
Industry
Male
113750
90045
18239
9043
5867
5385
2366
1400
842
251
56
2
Female
35363
18493
1974
1047
560
236
68
0
0
2
0
0
Fuel
Male
54835
32466
13052
10521
11300
11605
4524
1523
686
305
3
0
Cycle
Female
5202
3562
913
530
82
111
33
19
0
3
0
0
Government
Male
61819
56932
8939
4091
2829
1119
402
21
0
0
0
0
Female
37394
24065
3270
1860
1007
559
0
0
0
0
0
0
Miscellaneous
Male
16534
9519
1754
619
603
444
132
166
17
32
8
0
Female
27982
13740
2608
1231
414
148
33
14
2
1
1
0
U.S. Total 715650 604963 161604 422436 247246 57743 140820 10455 136152 68155 29828 46174
MD Measurable dose.
-------
00
Table C-3. Estimated collective dose to exposed workers
by dose range, occupation, and sex, 1980
Annual
Collective dose (person-rem)
dose
equivalent Total
(rem) Hale Female
0-MD
MD-0.1
0.1-0.25
0.25-0.5
0.5-1
1-2
2-3
3-4
4-5
5-8
8-12
12+
U.S. Total
383
6701
8150
11426
18101
28928
19544
12137
7326
4380
829
25
117930
901
6591
5570
5268
5364
4735
1733
838
419
497
154
0
32070
Medicine
Hale Female
142
1880
1971
2245
2930
3371
1873
1106
575
806
209
0
17108
708
4963
4150
3707
3725
3191
1400
730
410
463
145
0
23592
Industry
Hale Female
82
2232
2553
3429
4486
7362
5392
4467
3454
1640
522
25
35644
33
438
341
339
380
334
179
0
0
12
0
0
2056
Nuclear
Fuel Cycle
Hale Female
96
1213
2145
3875
8343
15700
11154
6064
3224
1739
26
0
53579
13
124
123
180
60
160
80
65
0
16
0
0
821
Government
Hale Female
16
1174
1240
1581
1912
1843
843
73
0
0
0
0
8682
18
535
522
698
906
839
0
0
0
0
0
0
3518
Miscellaneous
Hale Female
47
202
241
296
430
579
282
500
73
195
72
0
2917
129
531
434
344
293
211
74
43
9
6
9
0
2083
MD Measurable dose.
-------
o
i
Table C-4. Estimated number of potentially exposed
workers by age, occupation, and sex, 1980
Number
of workers
Nuclear
Age
(yr)
18-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65+
U.S.
Total
Total
Male
8035
84336
141742
157869
104636
69220
52934
39650
30781
14489
5958
715650
Female
25090
168534
158986
94237
57865
38649
24760
17608
12360
5389
1485
604963
Medicine
Male
1749
12564
31685
40135
27789
15502
12070
8030
6635
3511
1934
161604
Female
18181
129697
118071
63440
37020
24003
14222
8775
5984
2325
718
422436
Industry
Male
3094
35296
53714
46704
33387
23722
18632
14672
11533
5259
1233
247246
Female
964
10148
12357
9168
7349
5310
4097
3738
3087
1374
151
57743
Fuel
Male
662
17905
29005
29816
20598
14107
10310
8929
6506
2473
509
140820
Cycle
Female
307
2811
3027
1973
923
666
251
337
139
14
7
10455
Government
Male
949
12448
27742
36770
20049
13777
10168
6462
4751
2089
947
136152
Female
1575
13599
17413
14427
8209
5058
3151
2156
1491
745
331
68155
Miscel-
laneous
Male
1581
6123
5596
4444
2813
2112
1754
1557
1356
1157
1335
29828
Female
4063
12279
8118
5229
4364
3612
3039
2602
1659
931
278
46174
MD Measurable dose.
-------
N)
O
Table C-5. Estimated collective dose to exposed workers
by age, occupation, and sex, 1980
Collective dose (person-rem)
Age
(YD
18-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65+
U.S. Total
Nuclear
Total
Male
841
17996
26082
25202
16750
11565
8148
5351
3983
1472
540
117930
Female
924
8306
8424
5187
3227
2385
1460
1105
699
267
86
32070
Medicine
Male Female
138 638
1573 6628
3005 6440
3718 3765
3063 2190
2169 1723
1454 940
910 654
600 403
320 158
158 53
17108 23592
Industry
Male
450
7193
9155
6926
4012
2772
2229
1391
921
414
181
35644
Female
32
449
400
299
229
147
164
133
135
64
4
2056
Fuel Cycle
Male
137
8498
11913
11696
7877
4950
3386
2456
2009
605
52
53579
Female
20
221
289
137
82
35
12
18
7
0
0
821
Government
Male
27
345
1359
2189
1482
1389
912
483
312
93
91
8682
Female
85
488
939
752
547
241
229
132
79
10
16
3518
Miscel-
laneous
Male
89
387
650
673
316
285
167
111
141
40
58
2917
Female
149
520
356
234
179
239
115
168
75
35
13
2083
MD Measurable dose.
-------
Table C-6. Hean annual dose equivalent to potentially
exposed workers by occupation, sex, and age, 1980
Hean annual dose equivalent fmrem)
Aqe
"SJ^
(yr)
18-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65+
U.S. Total
Nuclear
Total
Hale
100
210
180
160
160
170
150
130
130
100
90
160
Female
40
50
50
60
60
60
60
60
60
50
60
50
Medicine
Hale
80
130
90
90
110
140
120
110
90
90
80
110
Female
40
50
50
60
60
70
70
70
70
70
70
60
Industry
Hale
150
200
170
150
120
120
120
90
80
80
150
140
Female
30
40
30
30
30
30
30
40
40
40
30
40
Fuel
Hale
210
480
410
390
380
350
330
280
310
240
100
380
Cycle
Female
70
80
100
70
90
50
50
50
50
20
0
80
Government
Hale
30
30
50
60
70
100
90
70
70
40
100
60
Female
50
40
50
50
70
50
70
60
50
10
50
50
Miscellaneous
Hale
60
60
120
150
no
130
100
70
100
30
40
100
Female
40
40
40
40
40
70
40
60
50
40
50
50
Table C-7. Hean annual dose equivalent to potentially
exposed workers by occupation and age, 1980
Hean annual dose equivalent (mrem)
Age
(yr)
18-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65+
Total
50
100
110
120
120
130
120
no
no
90
80
Medicine
40
60
60
70
80
100
90
90
80
80
80
Industry
120
170
150
130
100
100
no
80
70
70
130
Nuclear
Fuel Cycle
160
420
380
370
370
340
320
270
300
240
100
Govern-
ment
40
30
50
60
70
90
90
70
60
40
80
Hi seel -
laneous
40
50
70
90
70
90
60
70
70
40
40
U.S. Total 110
70
120
360
60
70
C-21
-------
Table C-8. Mean annual dose equivalent to measurably exposed
workers by occupation, sex, and age, 1980
Mean annual dose
equivalent (mrem)
Nuclear
Age
(yr)
18-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65+
U.S. Total
Total
Male
220
420
320
290
290
290
280
240
250
210
140
300
Female
110
120
120
120
130
130
100
130
110
110
80
120
Medicine
Male
140
220
180
190
210
240
230
200
170
170
120
200
Female
100
120
120
130
120
150
100
150
190
130
110
120
Industry
Male
290
440
300
260
220
210
220
170
180
160
220
270
Female
140
120
90
80
80
70
100
80
100
140
40
90
Fuel
Male
680
760
700
620
610
510
650
470
490
420
140
620
Cycle
Female
290
180
160
140
150
140
110
90
120
20
0
160
Government
Male
50
50
90
110
140
190
140
150
110
140
140
120
Female
170
80
130
110
160
90
130
120
100
40
60
110
Miscellaneous
Male
160
160
240
310
240
300
220
150
240
90
90
220
Female
100
100
100
110
240
150
90
150
90
80
70
110
Table C-9. Mean annual dose equivalent to measurably
exposed workers by occupation and age, 1980
Mean annual dose equivalent (mrem)
Age
(yr)
18-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65+
U.S. Total
Total
140
230
230
230
240
240
220
210
210
190
130
230
Medicine
100
130
140
150
160
190
150
180
150
150
110
150
Industry
270
380
270
240
200
190
200
160
170
160
200
240
Nuclear
Fuel Cycle
580
710
650
600
590
500
640
460
490
420
140
600
Govern-
ment
110
70
100
110
140
160
140
140
110
120
120
120
Miscel-
laneous
120
120
160
150
240
210
140
150
150
80
80
160
C-22
-------
56 processors that participated in a 1981-1982 study, the mean bias for
"deep" dose was 0.24 for low energy photons and 0.07 for high energy
photons (P183). The study included both thermoluminescent and film type
dosimeters. The commercial dosimetry data used in the present study had
less bias. The corresponding mean biases were 0.01 (film) and 0.09 (TLD)
for low energy photons and 0.04 (film) and 0.01 (TLD) for high energy
photons. The performance of dosimeters by all 56 processors for other
radiations are discussed below.
B. Dosimeter Performance
A recent NRC-sponsored study of personnel dosimeter performance
(P183) indicated that many processors would have difficulty passing the
performance standards proposed by the Health Physics standards Committee
and subsequently adopted by the American National Standards Institute
as N13.11 on June 17, 1982 (ANS183). In a series of three tests, 22%
(May-October 1978), 14% (November 1978-April 1979) and 11% (November
1981-April 1982) of individual dosimeters were in error by more than
50%.
Test #3 of the NRC study (November 1981-April 1982) showed improved
results for the absolute value of the mean bias, P, of reported doses
for a number of types of radiation. P is defined:
i n
P = £ I (DrD0)/D0,
where D - reported dose, D = delivered dose, and n - number of
reported doses (all D values were less than 10,000 mrem).
The absolute values of the mean bias for all tested dosimeters
from all processors were (a) 0.24 (deep) and 0.33 (shallow) for low
energy photons [x rays from 15 to 30 kev], (b) 0.07 (deep) for high
energy gamma rays [cesium-137 gammas from 1.1 to 2.0 Mev], (c) 0.19 for
strontium-90 betas, (d) 0.15 for moderated californium-252 neutrons plus
C-23
-------
high energy photons, (e) 0.21 (deep) and 0.31 (shallow) for a high and
low energy photon mixture, (f) 0.12 (deep) and 0.17 (shallow) for high
energy photon and beta mixtures.
The terms "deep" and "shallow" refer to absorbed doses delivered
at 1.0 and 0.007 cm depths, respectively, in a standard ICRU soft tissue
sphere (see ICRU Report 25). If we assume that all dosimeters of this
study, excluding accident categories, are representative of dosimetry
used for U.S. workers, the average weighted (absolute) bias was 0.21
for the determination of mean doses in 1981-82.
Not all dosimetry data are equally reliable. The number of indivi-
dual dosimeters irradiated in Test #3 that were within a 50% tolerance
limit for P, were 98% (military), 97% (private industry), 91% (nuclear
power plants), 90% (national laboratories), 87% (DOE prime contractors),
and 86% (all commercial processors). The corresponding mean perform-
ances within a + 30% tolerance limit for P were 89% (military), 81%
(national laboratories), 81% (nuclear power plants), 75% (DOE prime
contractors), and 76% (all commercial processors). The commercial
dosimetry data used for this study had even better performance results
than the military. The corresponding performances within a + 50% and
+ 30% tolerance limit for P were 99.4% and 97.0%, respectively. These
results were obtained under test conditions for which it might be
expected that each participating processor would do its best. Since
Test #2 was conducted in 1978-1979 and Test #3 was conducted in 1981-
82, it was assumed that actual performance for U.S. dosimetry in 1980
was intermediate between Test #2 and Test #3 results, giving a predicted
bias of between 0.24 (Co80) and 0.21 (P183).
VI. COMPARISON OF DOSES TO FULL-TIME WORKERS AND DOSES TO
COMBINED PART- AND FULL-TIME WORKERS
Tn this report we summarize all exposure data for a given year,
since the purpose of this study is to assess total worker exposure.
C-24
-------
some of these exposure data are for "part-time" workers who were
employed (or, more precisely, monitored) for shorter periods than one
year. Thus, these mean doses for combined part- and full-time workers
will be lower than for full-time workers only.
We made a cursory examination of the above two types of mean doses
for four groups of workers (hospital, dental, nuclear power, and Indus
trial radiography workers) using a sample of commercial data, which
contains quarterly dose records. (The mean doses for these samples of
workers are not necessarily the same as i.hone reported for our general
results because they are calculated from incomplete data.) The mean
doses for full-time workers only and for all workers are shown in Table
C-10; the differences ranged from 0-50%. The differences in mean dose
were generally less for those workers receiving measurable doses than
for all monitored workers.
Table C-10. Mean annual dose equivalent to full-time workers
and to combined part- and full-time workers
Mean annual dose equivalent (mrem)
Part- and full-time workers Full-time workers only
Worker Group All Exposed* All Exposed*
Dentistry 20 70 30 70
Hospital 140 200 200 240
Industrial
Radiography 300 440 410 530
Nuclear Power
Reactor 740 900 1110 1340
*Workers who received a measurable dose in any monitoring period.
C-25
-------
APPENDIX D
FEDERAL AGENCY EXPOSURE DATA FOR 1980
-------
CONTENTS
TABLES
Page
D-l. Summary of Federal Occupational Radiation Exposure Data,
1980 D-5
D-2. Department of Energy/Department of Energy Contractors.
Occupational Radiation Exposures, 1980 D-6
D-3. U.S. Navy, Occupational Radiation Exposures, 1980 D-7
D-4. U.S. Army, Occupational Radiation Exposures, 1980 D-8
D-5. U.S. Air Force, Occupational Radiation Exposures, 1980. . . . D-9
D-6a. U.S. Public Health Service, Occupational Radiation
Exposures by Age, 1980 D-10
D-6b. U.S. Public Health Service, Occupational Radiation
Exposures by Occupation, 1980 D-ll
D-7. National Aeronautics and Space Administration,
Occupational Radiation Exposures, 1980 D-12
D-8. National Bureau of Standards, Occupational Radiation
Exposures, 1980 D-12
D-9. National Institutes of Health, Occupational Radiation
Exposures, 1980 D-13
D-10. Nuclear Regulatory Commission, Licensee Occupational
Radiation Exposures, 1980 D-14
D-ll. Mine Safety and Health Administration, Occupational
Radiation Exposures - Underground Uranium Miners,
1980
D-3
-------
Table D-l. Summary of Federal occupational radiation exposure data, 1980
Dose equivalent range (rem)
Federal
Agency
DOE<*>
DOD
Mavy(b>
Army
Air Force(c)
Subtotal
0-HD MO-0.1
44,519 28,523
14,852 37,230
12,946 7,534
14,214 3,636
42,012 48,400
0.1- 0.25-
0.25 0.5
4,538 2,587
6,838 3,114
331 137
177 36
7,346 3,287
0.5-
0.75
1,225
1,098
48
13
1,159
0.75-
1
687
679
20
3
702
1-2
1,112
517
29
3
549
2-3
387
4
5
3
12
3-4
16
3
0
0
3
4-5
0
0
0
0
0
5-6
0
0
0
0
0
6-7
0
0
0
0
0
7-8
0
0
0
0
0
8-9
0
0
0
0
0
>9
0
0
0
0
0
Total
number of
monitored
workers
83,594
64,335
21,050
18,085
103,470
Other agencies
NASA
NBS
NIH
PHS
VAW)
Subtotal
NRC
715 172
182 202
2,806 1,245
5,278 525
3,607 1,881
12,588 4,025
63,684 37,915
16 2
39 4
71 14
56 19
139 37
321 76
14,449 11,377
2
3
8
9
21
43
6,931
0
7
5
1
6
19
5,044
Exposure
Federal
Agency
MSHA
Uranium
Miners
0-HD HD-0. 1
5,928 1,146
0.1- 0.2-
0.2 0.3
759 550
0.3-
0.4
437
0.4-
0.5
336
1
2
4
4
6
17
12,262 4
0
0
1
0
2
3
,779
range (working
0.5-
0.6
339
1
0
0
0
1
2
1,644
0
0
0
0
0
0
761
0
0
0
0
0
0
204
0
0
0
0
0
0
103
0
0
0
0
0
0
19
0
0
0
0
0
0
5
0
0
0
0
0
0
0
level month)
0.6- 0.7-
0.7 0.8
281
297
0.8-
0.9
299
0.9-
1 1-2
296 1,913
2-3
731
3-4
159
>4
13
909
439
4,154
5,892
5,700
17,094
159,177
Total
number of
monitored
workers
13,484
not include uranium enrichment and visitors (see Table D-2).
(^includes an additional 3,731 persons in Navy contractor shipyards.
(^Distribution of doses recalculated using the HLN model because of different dose ranges (see Table D-5).
(^Distribution of closes is based on commercial data.
HO = Measurable dose.
-------
Table 0-2. Department of Energy/Department of Energy contractors, occupational
radiation exposures, 1980
Workers in
Facility
Type
Reactor
Research
Fuel
Fabrication
Fuel
Processing
Uranium
Enrichment
Weapons
Fabrication
and Testing
Gen. Research
Accelerator
Other
Visitors
DOE Offices
Totals
Number
Monitored
6921
2102
3147
1871
5904
36110
5315
12037
87590
2058
173055
Less
than
Meas.
2654
734
778
535
8659
22933
3347
3870
77045
1544
122099
Meas.
-0.10
2569
793
1041
861
5967
10749
1244
5670
10109
490
39493
0.10
-0.25
699
266
356
364
629
1225
360
982
341
21
5243
Dose Equivalent Range (rem)
0.25
-0.50
449
143
329
87
315
558
159
631
62
3
2736
0.50
-0.75
171
57
199
19
143
296
77
282
18
_o
1262
0.75
-1.00
77
43
116
4
82
155
45
169
9
0
700
1-2
165
55
237
1
93
163
70
329
4
_o
1117
2-3
135
11
91
0
14
24
11
101
2
0
389
3-4
2
0
0
0
2
7
2
3
0
0
16
>4
0
0
0
0
0
0
0
0
0
0
0
Collective
Dose
(person-
rein)
1185
323
1047
156
869
1611
412
1773
619
29
Collective Dose
(person-ran)
1975 918 1026 789 612 1676 972 56
8024
D-6
-------
Table D-3. U.S. Navy,* occupational radiation exposures, 1980
Range (rem)
No measurable dose
0.001-0.019
0.020-0.049
0.050-0.099
0.100-0.249
0.250-0.499
0.500-0.749
0.750-0.999
1.000-1.249
1.250-1.499
1.500-1.749
1.750-1.999
2.000-2.249
2.250-2.499
2.500-2.749
2.750-2.999
3.000-3.249
3.250-3.499
3.500-3.749
3.750-3.999
>4.0
Total personnel monitored
Total collective dose (person-rem)
Number of personnel
14,005
18,080
9,757
7,269
6,448
2,936
1,035
640
223
118
55
31
1
1
2
0
1
0
0
2
0
60,604
4,793
*Excludes Navy contractor shipyards.
D-7
-------
Table 0-4. U.S. Army, occupational radiation exposures, 1980
Whole-body
exposure range
(rem)
Number of
personnel
Collective dose
(person-ran)
No measurable dose
Exposure less than 0.100
0.100 to 0.250
0.250 to 0.500
0.500 to 0.750
0.750 to 1.000
1.000 to 2.000
2.000 to 3.000
3.000 to 4.000
4.000 to 5.000
Total
12,946
7,534
331
137
48
20
29
5
0
0
21,050
00.00
119.09
50.63
48.34
28.92
17.61
40.23
12.95
0.00
0.00
317.77
D-8
-------
Table 0-5. U.S. Air Force,* occupational radiation exposures, 1980
Occuoational cateoorv
•" *"*
Dose equivalent ranqe (mrem) ^^
1- 101- 201- 301- 401- 501- 601- 701- 801- 901- 1001- 2001- dose
100 200 300 400 500 600 700 800 900 1000 2000 3000 (person-mrem)
Medical maintenance 449 126 1 1 1 0 0 0 0 0 0 0 0
Hedical x-ray technician 860 937 46 11 6 1 2 0 1 0 0 1 0
X-ray physician: radiologist 68 111 22 3 1 2 0 1 0 1 0 0 0
X-ray physician: all others 172 86 11 21020000 0 0
X-ray nurse/nurse
anesthesiologist 284 130 100000000 0 0
TOTALS
14,214 3,636 156 37 16
Total monitored: 18,085
2,360
42,500
11,795
5,849
2,286
Medical technician
Medical x-ray student
Dental technician
Dentist: general
Dentist: oral surgeon
Dental x-ray student
Veterinarian
Veterinarian: technician
Military working dog handler
Radioisotopes: physician
ftadioisotopes: technician
Radioisotopes: nurse
Industrial radio! sotopes
Industrial x-ray
Industrial x-ray: student
Radar personnel
Special weapons
Professionals
Air Force contractors
Radioactive waste disposal
Maintenance personnel
Aonin. & supply personnel
Disaster control personnel
Explosive ordnance
disposal personnel
Visitors
All others
713
178
2.940
556
55
444
88
163
35
36
96
6
1,303
2,126
160
134
294
647
65
17
205
142
48
701
1,080
149
152
3
288
56
4
7
30
42
19
25
61
10
179
833
22
63
99
122
20
0
70
12
6
60
51
12
4
0
1
0
0
1
0
0
1
4
18
1
4
32
0
0
0
3
0
0
6
0
0
0
0
0
2
0
0
0
0
0
0
0
0
0
7
0
2
8
0
0
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
4
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
5
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3,648
50
2,269
417
0
231
636
803
437
1,229
23,467
365
3,806
28,190
170
10
337
3,849
856
0
1,708
80
301
747
18
10 1 4 1 0 3 3 138.844
Average dose equivalent =7.68 mrem
*Compiled from the USAF Master Radiation Repository, Brooks AFB, Texas, January 1983.
D-9
-------
Table D-6a. U.S. Public Health Service,* occupational radiation exposures by age, 1980
Dose equivalent range (mrem)
Age
(yr)
Under
18
18-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65+
Total
<10
4
11
445
1,063
1,295
816
548
389
321
190
94
102
5,278
10-
24
0
a
ll
46
69
w
57
24
21
18
10
7
4
267
25-
49
0
0
10
26
28
22
23
12
12
12
3
3
151
50-
74
0
0
5
4
13
13
7
9
6
3
2
3
65
75-
99
0
0
6
4
12
6
3
4
4
1
1
1
42
100-
249
0
0
3
7
12
7
9
8
8
1
0
1
56
250-
499
0
0
1
1
6
5
1
3
0
0
1
1
19
500-
749
0
0
0
2
2
4
1
0
0
0
0
0
9
750-
999
0
0
1
0
0
0
0
0
0
0
0
0
1
1,000-
4,999
0
0
0
0
2
2
0
0
0
0
0
0
4
Total
personnel
monitored
4
11
482
1,153
1,439
932
616
446
369
217
108
115
5,892
Collective
dose
(person-mrem)
0
0
3,030
4,690
11,330
10,460
4,175
3,645
2,400
1,040
690
1,120
42,580
*See footnote at end of Table D-6b.
D-10
-------
Table 0-6b. U.S. Public Health Service,* occupational radiation exposures by occupation, 1980
Dose equivalent ranae (mrern)
Occupation
Radiologist
Physician
Dentist
X-ray tech.
Dental tech.
Tech. other
Nurse
Scientist
Nuclear tech.
Other
Total
<10
37
479
560
315
851
1,206
456
870
2
502
5,278
10-
24
3
11
18
31
26
55
33
57
2
31
267
25-
49
8
10
7
33
11
19
11
25
1
26
151
50-
74
3
5
2
17
4
11
4
11
0
8
65
75-
99
1
6
1
11
1
9
4
6
0
3
42
100-
249
6
5
3
10
5
9
1
9
2
6
56
250-
499
1
4
2
2
1
2
0
3
1
3
19
500-
749
3
1
0
3
0
1
0
0
0
1
9
750-
999
0
0
0
0
0
1
0
0
0
0
1
1,000-
4,999
2
0
0
0
0
2
0
0
0
0
4
Total
personnel
moni tored
64
521
593
422
899
1,315
509
981
8
580
5,892
Collective
dose
(person-mrem)
5,845
4,400
2,035
7,590
1,975
9,120
1,555
4,935
565
4,560
42,580
*In 1980, the PHS Personnel Monitoring Program monitored workers in the following agencies:
Indian Health Service, PHS Hospitals, U.S. Coast Guard, Food and Drug Administration (including
the Center for Devices and Radiological Health and others), Bureau of Prisons, Centers for
Disease Control (including the National Institute for Occupational Safety and Health), U.S.
Capitol Police, PHS Outpatient Clinics, National Institutes of Health (National Institute of
Environmental Health Sciences and Gerontology Research Center only), Environmental Protection
Agency, U.S. Customs, Supreme Court Police, National Institute for Mental Health (St. Elizabeth's
Hospital), Occupational Safety and Health Administration, Federal Bureau of Investigation, U.S.
Senate Post Office, National Center for Health Statistics, U.S. Merchant Marine Hospitals, and
Federal Emergency Management Agency.
D-ll
-------
Table D-7. National Aeronautics and Space Administration,
occupational radiation exposures,* 1980
Total Exposure range (rem)
personnel Less than 0.10 0.25 0.50 0.75
monitored measurable <0.10 0.25 0.50 0.75 1.00 1-2 2-3 3-4 4-5
909
715
172
16
1
1
^Occupational categories of personnel monitored include:
Health physicist
Maintenance worker
Inspector
Aircraft technician
Electronics technician
Biomedical engineer
Reactor worker
Medical technician
Nurse
Physician
Chemi st
Animal caretaker
Industrial radiologist
Scientist
X-ray technician
Warehouse worker
Other
Table D-8. National Bureau of Standards, occupational
radiation exposures, 1980
Dose range (rem)
Number of workers
No measurable dose (MD)
MD less than 0.10
0.10 - 0.25
0.25 - 0.50
0.50 - 0.75
0.75 - 1.00
1.00 - 2.00
2.00 - 3.00
3.00 - 4.00
4.00 - 5.00
Total
182
202
39
4
3
7
2
0
0
0
439
D-12
-------
Table D-9. National Institutes of Health*, occupational
radiation exposures, 1980
Exposure range (rem)
No measurable dose
0.0 - 0.1
0.1 - 0.25
0.25 - 0.5
0.5 - 0.75
0.75 - 1.0
1.0 - 2.0
2.0 - 3.0
3.0 - 4.0
4.0 - 5.0
5.0 - 6.0
6.0 - 7.0
7.0 - 8.0
8.0 - 9.0
9.0 - 10.0
10.0 - 11.0
11.0 - 12.0
12.0*
Total
Number of individuals
2,806
1,245
71
14
8
5
4
1
0
0
0
0
0
, 0
0
0
0
o
4,154
*Data is for the Isotope Laboratory, NIH, Bethesda, Maryland, complex
only.
D-13
-------
Table D-10. Nuclear Regulatory Commission, licensee occupational radiation exposures, 1980
Number of individuals with whole-body doses in
No
ranges (rem)
Measur-
measurable able to 0.10- 0.25- 0.50-
Li cense category
Industrial radiography
Single location
Multiple locations
Subtotal
Hanuf. & Distrib.
Broad
Other
Subtotal
Fuel Fab. & Reproc.
Power reactors*
BWRs
PWRs
Subtotal
Total
dose
740
3,806
4,546
2,007
652
2,659
4,304
13,971
38,204
52,175
63,684
<0.10
579
2,291
2,870
893
547
1,440
3,737
9,765
20, 103
29,868
37,915
0.25
134
1,046
1,180
313
109
422
1,082
4,671
7,094
11,765
14,449
0.50
87
776
863
155
28
183
510
4,283
5,538
9,821
11,377
0.75
32
478
510
83
2
85
254
2,803
3,279
6,082
6,931
0.75- 1.0-
1.0
12
303
315
42
2
44
167
2,090
2,428
4,518
5,044
2.0
19
496
515
126
10
136
137
5,884
5,590
11,474
12,262
2.0-
3.0
4
186
190
61
1
62
12
2,831
1,684
4,515
4,779
3.0-
4.0
2
66
68
35
3
38
1
1,073
464
1,537
1,644
4.0-
5.0
0
33
33
41
1
42
0
503
183
686
761
5.0-
6.0
1
5
6
6
0
6
0
129
63
192
204
6.0-
7.0
0
3
3
2
0
2
0
60
38
98
103
7.0-
8.0
1
0
1
0
0
0
0
2
16
18
19
8.0-
9.0
0
2
2
0
0
0
0
0
3
3
5
>9
0
0
0
0
0
0
0
0
0
0
Total
Total dose
number
monitored
1,611
9,491
1 1 , 102
3,764
1,355
5,119
10,204
48,065
84,687
132,752
159,177
(person -
rem)
174
2,805
2,979
941
92
1,033
1,111
29,530
24,544
54,074
59,197
*Includes all light water reactors (BWR-Boiling Mater Reactor; PWR-Pressurized Water Reactor) that reported, although all of them may not have been
in commercial operation for a full year. This does not include data from the one commercial gas-cooled power reactor.
-------
Table 0-11. Hine Safety and Health Administration,
occupational radiation exposures - underground uranium miners,* 1980
Exposure range
(WIM)
0 - ME
ME - 0.1
0.1 - 0.2
0.2 - 0.3
0.3 - 0.4
0.4 - 0.5
0.5 - 0.6
0.6 - 0.7
0.7 - 0.8
0.8 - 0.9
0.9 - 1.0
1.0 - 2.0
2.0 - 3.0
3.0 - 4.0
>4
Total
Number of miners
5,928
1,146
759
550
437
336
339
281
297
299
296
1,913
731
159
13
13,484
Exposure data are for radon decay products in units of working level
months (WIN) (see definition on p. 20).
ME Measurable Exposure.
D-15
-------
APPENDIX E
OCCUPATIONAL EXPOSURE SUMMARIES
FOR 1960, 1970, AND 1975
-------
CONTENTS
TABLES
Page
E-l. Occupational Exposure Summary for 1960 E-5
E-2. Occupational Exposure Summary Eor 1970 E-6
E-3. National Occupational Exposure Summary Eor 1975 E-7
E-3
-------
Table E-l. Occupational exposure stannary for 1960*
Occupational group
Number of
persons
Mean whole-body
dose
(millirem)**
A. Federal Agencies
U.S. Air Force
U.S. Army
U.S. Navy
1. Nuclear Propulsion Program
a. government
b. contractor
2. Non-Nuclear Navy (government)
Atomic Energy Comission and
Contractors (some Federal - mostly
contractor employees)
Public Health Service (PHS)tb)
Bureau of Radiological Health (HEW)
Mining Enforcement and Safety
Administration (privately employed
uranium miners)
National Aeronautics and Space
Administration
National Bureau of Standards
National Institutes of Health
6,800
16,400
4,685
10,394
7,420
82,195
1,500
5,800
200
100
530
30
30
230
50
220
220
SUBTOTAL, Federal Agencies
B. Healing Arts
C. Industry
136,024
250,000
50,000
170'
TOTAL
436,024
*Source: "Occupational Exposure to Ionizing Radiation in the United States:
A Comprehensive Summary for the Year 1975" (Co80).
**Values for mean whole-body dose are rounded to the nearest 10 millirem.
***Mean whole-body dose for AEC and Department of Defense personnel and
contractor personnel.
E-5
-------
Table E-2. Occupational exposure summary for 1970* (Co80)
Category
AEC
Contractors
Reporting Licensees
AEC
Agreement State
Non-reporting Licensees
AEC
Agreement State
Military
Army
Air Force
Navy
PHS
Other Federal
Number of
persons
102,918
62,090
24,519
93,000
3,000
7,445
17,591
55,051
508
2,000
Collective
dose
(person-rem)
20,361
13,365
6,715
5,022
822
744
1,555
10,879
65
258
Mean whole-body
dose per person
(mi 1 1 i rem)
198
215
274
54
274
100
88
198
129
129
Medical
Radium
Non-Federal
Medical x-ray
Dental x-ray
37,925
194,451
171,226
20,480
62,253
21,403
540
320
125
TOTAL
771,814
163,922
210
*Source: Estimates of Ionizing Radiation Doses in the United States 1960-
2000, USEPA, Office of Radiation Programs, Criteria and Standards Division,
Table IV-4, Page 148.
E-6
-------
Table E-3. National occupational exposure sunroary for 1975^
Occupational subgroup
MEDICINE
Hospital /Clinic
Private Practice
Dental
Podiatry
Chiropractic
Veterinary
Entire Subgroup
INDUSTRY Exposed^)
220
160
20
10
30
80
90
290
100
110
350
40
130
390
270
50
310
20
340
400
410
140
30
110
230
320
580
610
370
630
200
520
760
560
70
920
50
630
Collective
dose
(person-rem)
22,000
21,700
5,800
100
400
1,400
51,400
5,700
11,400
5,900
2,500
200
25,600
21,400
3,100
400
100
—
24,900
See footnotes at end of table.
E-l
-------
Table E-3. National occupational exposure summary for 1975 (Continued)
Occupational subgroup
Number of workers
(b) (c)
Total Exposed
Mean whole-body dose
(millirem)
Total ^ Exposed (c*
ALL WORKERS
1,106,900 369,100
120
350
Collective
dose
(person-ran)
GOVERNMENT
Dept. of Energy 80,954 39,451 150 300 11,800
Oept. of Defense 92,500 55,800 110 180 10,100
Other Federal Govt. 13,400 4,400 90 280 1,300
Entire Subgroup 186,800 99,700 120 230 23,100
MISCELLANEOUS
Education (faculty):
2-year Institutions
4-year Institutions
Transportation
Entire Subgroup
7,000
14,800
77,000
98,800
2,300
4,900
11,800
19,000
»w
80 w
30
40
170
230
200
200
400
1,100
2,300
3,800
128,800
ADDITIONAL GROUPS(f)
Transportation
(Flight Attendants;
radionuclides) 30,000 10,000
Education (Students):
2-year Institutions 35,000 11,700
4-year Institutions 54,800 18,300
60
80
(e)
(e)
10
170
230
100
2,000
4,200
All Additional Groups 119,800
40,000
50
150
6,100
*Source: "Occupational Exposure to Ionizing Radiation in the United States:
A Comprehensive Summary for the Year 1975" (Co80).
(^Extrapolated numbers of workers are rounded to the nearest 100, mean doses to the
nearest 10 mrem, and collective doses to the nearest 100 person-rents.
C^AII monitored and unmonitored workers with potential occupational exposure.
(^Workers who received a measurable dose in any monitoring period during the year.
W)"Licensee" means NRC and NRC agreement state licensees for use of radionuclides.
Doses from electronic (e.g., x-ray) sources are also included. "Registrant" means
state registrants who have electronic sources only.
te)These estimated doses are based on small samples that may not be representative.
(f)Persons who are only incidentally exposed or not normally considered workers; the
estimates listed are very uncertain.
B-8
-------
APPENDIX F
THE HYBRID LOGNORMAL AND JOHNSON S_ DISTRIBUTIONS
D
-------
CONTENTS
Page
I. THE HYBRID LOGNORMAL DISTRIBUTION p-5
II. THE JOHNSON SB DISTRIBUTION F-9
FIGURES
F-l. Lognorraal and hybrid lognormal probability displays of dose
distributions for all light water reactor (LVR) workers,
1982, and for a sample of male and female hospital and
nuclear power workers, 1980 F-6
F-2. Active control parameter pfrenT1) versus average annual
dose for all light water reactor (LWR) workers and by sex
for a sample of hospital and nuclear power workers, 1975
and 1980 F-8
F-3. Johnson SB probability plot of the distributions of
age (Y) by sex for a sample of hospital and nuclear
power workers, 1980 F-ll
F-3
-------
APPENDIX F
THE HYBRID LOGNORMAL AND JOHNSON S0 DISTRIBUTIONS
B
We made extensive use of two statistical distributions: the hybrid
lognorraal (HLN) distribution to analyze the distributions of workers and
collective dose as a function of dose, and the Johnson s_ distribution
D
to analyze the distribution of workers and collective dose as a function
of age. A brief description and mathematical expression are given here
for each of these distributions, but the interested reader should refer
to the appropriate references for further detail. We also illustrate
briefly our use of these statistical distributions with several groups
of workers.
I. THE HYBRID LOGNORNAL DISTRIBUTION
The hybrid lognormal (HLN) distribution is the transformation of
of the variable x given by (Inpx + ?x) that has a normal distribution
with mean v and variance a2 (Ku81). The variable x is the dose equiva-
lent (in units of rem) and /> is a parameter (in units of reciprocal
rem) indicating the degree of active control used to avert some level
of radiation exposure. The HLN distribution is derived from the
lognormal distribution by including a feedback mechanism that relates
active control of future doses to previous cumulative doses (Ku82a,
Ku82c). The HLN distribution is similar to the lognormal distribution
in lower range values of />x and to the normal distribution In upper
range values of px.
P-5
-------
99.9999
99.999
99.99
g 99.9
u. 99
O
UJ
U
I 95
uj go
80
70
60
SO
40
30
20
D
u
10
0.01
0.1 1
ANNUAL DOSE EQUIVALENT (ram)
10
50
99.999
S
Ul
3
5
O
95
90
80
70
60
SO
40
30
20
10
0.001 0.01 0.1
1 5 10 15
P TIMES ANNUAL DOSE EQUIVALENT
20
25
Figure F-1. Lognormal and hybrid lognormal probability displays of dose
distributions for all light water reactor (LWR) workers, 1982, and for a
sample of male and female hospital and nuclear power workers, 1980.
P-6
-------
The HLN distribution function, ft(x), is given by
px
- (tnt + t -
L- [I + 1] exp \
2ir o ^t / L
02 i dt' (F~1)
e. O I
( O < X < co, o5) corresponds to the more sharply curved
region of the lognormal presentations of the same data.
Figure F-2 shows the estimated active control parameter p as a
function of the mean annual dose equivalent for three worker groups in
F-7
-------
T 3
O
CC
I
O,A, V, Q -1975
• AT. • -1980
All LWRs
(NUREG-0713,Vol.2)
Female
Nuclear Power Plants
0.2 0.4 0.6
MEAN ANNUAL DOSE EQUIVALENT (rem)
0.8
1.0
Figure F-2. Active control parameter p (rem~1) versus average annual dose
for all light water reactor (LWR) workers and by sex for a sample of
hospital and nuclear power workers, 1975 and 1980.
F-8
-------
1975 and 1980 (Ne82). Worker groups with higher mean annual dose equiv-
alents show higher active control. Bach of the indicated regions
encircling the mean values of p in Figure F-2 represent the extent of
variation of the active control parameter according to mean dose in
different age groups for the hospital and nuclear power groups. The
variation of p for All Light Water Reactors (All LWRs) represents the
extent of yearly variations from 1915 to 1980. The group of nuclear
power workers from commercial dosimetry data is a subset of the All LWR
group of the NRG. The workers of this subset incurred higher mean
annual exposures than for All LWR workers.
The HLN distribution model proved useful in consistently fitting
annual dose distribution data and analyzing annual collective dose
distributions. We also used the HLN model for analysis of annual dose
data and termination data where it provided a measure of the degree of
active control used to reduce, respectively, the frequency of annual
doses approaching dose limits and the accumulated career doses of
workers according to their length of employment. Finally, we used the
HLN distribution model for predicting the 1985 dose distributions for
the five occupational categories and for all workers from the trends of
the corresponding distributions for the period 1960 to 1980.
II. THE JOHNSON S_ DISTRIBUTION
D
Workers potentially exposed to radiation, like most workers, are
primarily distributed between 18 and 65 years of age. For modeling
purposes, such workers can be considered to have a lower age limit of
18 years and an upper age limit of 65 years. The Johnson SB distribu-
tion (double-bounded lognormal) is particularly well suited to fitting
such age distributions where there are relatively sharp cut-offs in
the number of persons below some age "a" and above some age "b". The
Johnson S distribution is the transformation of variable y given by
In {(y-a)/(b-y)} that has a normal distribution with mean v and with
F-9
-------
variance o2 (Ai57, Jo70). The Sn distribution function is given by
D
y
/(b-a) f (ln{(t-a)/(b-t)} - y)2~|
exp dt, (F-3)
(t-a)(b-t) V L 2 0' J
a
( a
-------
99.999
99.99 -
Nuclear Power, Female
a = 20, b = 70
Nuclear Power, Male
a = 18.5, b = 78
Hospitals, Female
a = 18, b = 80
Hospitals, Male
a = 17, b = 85
Note: y, a, and b, are in years.
0.1
0.01
0.01
(y-a)/(b-y)
Figure F-3. Johnson SB probability plot of the distribution of age (Y) by sex for
a sample of hospital and nuclear power workers, 1980.
F-ll
-------
APPENDIX G
FEDERAL RADIATION PROTECTION GUIDANCE
-------
CONTENTS
Page
I. RADIATION PROTECTION GUIDANCE FOR FEDERAL AGENCIES
(25 FR 4402), MAY 18, 1960 G~5
II. RADIATION PROTECTION GUIDANCE FOR FEDERAL AGENCIES:
UNDERGROUND MINING OF URANIUM ORE, (36 FR 12921),
JULY 9, 1911 0-7
G-3
-------
4402
Reprint from Federal Register - 5/18/60
FEDERAL RADIATION COUNCIL
RADIATION PROTECTION GUIDANCE
FOR FEDERAL AGENCIES
Memorandum for the President
Pursuant to Executive Order 10831 and
Public Law 86-373, the Federal Radia-
tion Council has made a study of the
hazards and use of radiation. We here-
with transmit our first report to you
concerning our findings and our recom-
mendations for the guidance of Federal
agencies in the conduct of their radia-
tion protection activities.
It is the statutory responsibility of the
Council to "* * ' advise the President
with respect to radiation matters, di-
rectly or indirectly affecting health,
including guidance for all Federal agen-
cies in the formulation of radiation
standards and in the establishment and
execution of programs of cooperation
with States • • *••
Fundamentally, setting basic radiation
protection standards involves passing
judgment on the extent of the possible
health hazard society is willing to accept
in order to realize the known benefits
of radiation. It involves inevitably a
balancing between total health protec-
tion, which might require foregoing any
activities increasing exposure to radia-
tion, and the vigorous promotion of the
use of radiation and atomic energy in
order to achieve optimum benefits.
The Federal Radiation Council has
reviewed available knowledge on radia-
tion effects and consulted with scientists
within and outside -the Government.
Each member has also examined the
guidance recommended in this memo-
randum in light of his statutory responsi-
bilities. Although the guidance does not
cover all phases of radiation protection,
such as internal emitters, we find that
the guidance which we recommend that
you provide for the use of Federal agen-
cies gives appropriate consideration to
the requirements of health protection
and the beneficial uses of radiation and
atomic energy. Our further findings and
recommendations follow.
Discussion. The fundamental problem
In establishing radiation protection
guides is to allow as much of the bene-
ficial uses of ionizing radiation as pos-
sible while assuring that man is not
exposed to undue hazard. To get a true
insight into the scope of the problem
and the impact of the decisions involved,
a review of the benefits and the hazards
is necessary.
It is important in considering both the
benefits and hazards of radiation to ap-
preciate that man has existed through-
out his history in a bath of natural
radiation. This background radiation,
which varies over the earth, provides a
partial basis for understanding the ef-
fects of radiation on man and serves as
an indicator of the ranges of radiation
exposures within which the human popu-
lation has developed and increased.
The benefits of ionizing radiation.
Radiation properly controlled is a boon
to mankind. It has been of inestimable
value in the diagnosis and treatment of
diseases. It can provide sources, of
energy greater than any the world has
yet had available. In industry, it is used
as a tool to measure thickness, quantity
or quality, to discover hidden flaws, to
trace liquid flow, and for other purposes.
So many research uses for ionizing radia-
tion have been found that scientists in
many diverse fields now rank radiation
With the microscope in value as a work-
ing tool.
The hazards of ionizing radiation.
Ionizing radiation involves health haz-
ards just as do many other useful tools.
Scientific findings concerning the bio-
logical effects of radiation of most im-
mediate interest to the establishment of
radiation protection standards are the
following:
1. Acute doses of radiation may pro-
duce immediate or delayed effects, or
both.
2. As acute whole body doses increase
above approximately 25 reins (units of
radiation dose), immediately observable
effects increase in severity with dose,
beginning from barely detectable
changes, to biological signs clearly indi-
cating damage, to death at levels of a
few hundred rems.
3. Delayed effects produced either by
acute irradiation or by chronic irradia-
tion are similar in kind, but the ability of
the body to repair radiation damage is
usually more effective in the case of
chronic than acute irradiation.
4. The delayed effects from radiation
are in general indistinguishable from
familiar pathological conditions usually
present in the population.
5. Delayed effects include genetic
effects (effects transmitted to succeeding
generations), increased incidence of
tumors, lifespan shortening, and growth
and development changes.
6. The child, the infant, and the un-
born infant appear to be more sensitive
to radiation than the adult.
7. The various organs of the body differ
in their sensitivity to radiation.
8. Although ionizing radiation can in-
duce genetic and somatic effects (effects
on the individual during his lifetime
other than genetic effects), the evidence
at the present time is insufficient to jus-
tify precise conclusions on the nature of
the dose-effect relationship at low doses
and dose rates. Moreover, the evidence
is insufficient to prove either the hypoth-
esis of a "damage threshold" (a point
below which no damage occurs) or the
hypothesis of ''no threshold" in man at
low doses.
9. If one assumes a direct linear rela-
tion between biological effect and the
amount of dose, it then becomes possible
to relate very low dose to an assumed
biological effect even though it is not de-
tectable. It is generally agreed that the
effect that may actually occur will not
exceed the amount predicted by this
assumption.
Basic biological assumptions. There
are insufficient data to provide a firm
basis for evaluating radiation effects for
all types and levels of irradiation. There
is particular uncertainty with respect to
the biological effects at very low doses
and low-dose rates. It is not prudent
therefore to assume that there is a level
of radiation exposure below which there
is absolute certainty that no effect may
occur. This consideration, in addition
to the adoption of the conservative hy-
poUiesis of a linear relation between bio-
logical effect and the amount of dose,
determines our basic approach to the
formulation of radiation protection
guides.
The lack of adequate scientific infor-
mation makes it urgent that additional
research be undertaken and new data
developed to provide a firmer basis for
. evaluating biological risk. Appropriate
member agencies of the Federal Radia-
tion Council are sponsoring and encour-
aging research in these areas.
Recommendations. In view of the
findings summarized above the following
recommendations are made:
It is recommended that:
1. There should not be any man-made
radiation exposure without the expecta-
tion of benefit resulting from such ex-
posure. Activities resulting in man-made
radiation exposure should be authorized
for useful applications provided in rec-
ommendations set forth herein are
followed.
It is recommended that:
2. The term "Radiation Protection
Guide" be adopted for Federal use. This
term is denned as the radiation dose
which should not be exceeded without
careful consideration of the reasons for
doing so; every effort should be made to
encourage the maintenance of radiation
doses as far below this guide as
practicable.
It is recommended that:
3. The following Radiation Protection
Guides be adopted for normal peacetime
operations:
Type of exposure
Radiation worker:
(ji) Whole body, head and trunk, active blood form-
ing organs, gonacls, or lens of oyo.
(b) Skin of whole body and thyroid
(c) Hands and forearms, feet and ankles
Population:
Condition
[Accumulated dose
(13 weeks
/Year
U<* weeks
(Year.
U3 works
Body burden .. .....
fYcnr
\13 weeks
Year
30 year . . .. .
Pose (rem)
5 times the number of years beyond
age 18.
3.
30.
10.
75.
25.
0.1 micrograni of mdluro-220 or Us
biological equivalent.
15.
5.
0.5 (whole body).
5 (goiiads).
The following points are made in re-
lation to the Radiation Protection
Guides herein provided:
CD For the Individual in the popula-
tion, the basic Guide for annual whole
body dose is 0.5 rem. This Guide ap-
G-5
-------
Wednesday, May 18, 1960
FEDERAL REGISTER
4403
plies when the individual whole body
doses are known. As an operational
technique, where the individual whole
body doses are not known, a suitable
sample of the exposed population should
be developed whose protection guide for
annual whole body dose will be 0.17 rem
per capita per year. It is emphasized
that this is an operational technique
which should be modified to meet spe-
cial situations.
(2) Considerations of population ge-
netics impose a per capita dose limitation
for the gonads of 5 rems in 30 years.
The operational mechanism described
above for the annual individual whole
body dose of 0.5 rem is likely in the im-
mediate future to assure that the go-
nadal exposure Guide (5 rem in 30
years) is not exceeded.
(3) These Guides do not differ sub-
stantially from certain other recom-
mendations such as those made by the
National Committee on Radiation Pro-
tection and Measurements, the National
Academy of Sciences, and the Interna-
tional Commission on Radiological
Protection.
(4) The term "maximum permissible
dose" is used by the National Committee
on Radiation Protection (NCRP) and
the International Commission on Ra-
diological Protection (ICRP). However,
this term is often misunderstood. The
words "maximum" and "permissible"
both have unfortunate connotations not
intended by either the NCRP or the
ICRP.
(5) There can be no single permissible
or acceptable level of exposure without
regard to the reason for permitting the
exposure. It should be general practice
to reduce exposure to radiation, and pos-
itive effort should be carried out to ful-
fill the sense of these recommendations.
It is basic that exposure to radiation
should result from a real determination
of its necessity.
(6) There can be different Radiation
Protection Guides with different numer-
ical values, depending upon the circum-
stances. The Guides herein recom-
mended are appropriate for normal
peacetime operations.
(7) These Guides are not intended to
apply to radiation exposure resulting
from natural background or the pur-
poseful exposure of patients by practi-
tioners of the healing arts.
(8) It is recognized that our present
scientific knowledge does not provide a
firm foundation within a factor of two
or three for selection of any particular
numerical value in preference to another
value. It should be recognized that the
Radiation Protection Guides recom-
mended in this paper are well below the
level where biological damage has been
observed in humans.
It is recommended that:
4. Current protection guides used by
the agencies be continued on an interim
basis for organ doses to the population.
Recommendations are not made con-
cerning the Radiation Protection Guides
for individual organ doses to the popu-
lation, other than the gonads. Unfor-
tunately, the complexities of establishing
guides applicable to radiation exposure
of all body organs preclude the Council
from making recommendations concern-
ing them at this time. However, current
protection guides used by the agencies
appear appropriate on an Interim basis.
It is recommended that:
5. The term "Radioactivity Concen-
tration Guide" be adopted for Federal
use. This term is defined as the concen-
tration of radioactivity in the environ-
ment which is determined to result in
whole body or organ doses equal to the
Radiation Protection Guide.
Within this definition, Radioactivity
Concentration Guides can be determined
after the Radiation Protection Guides
are decided upon. Any given Radioac-
tivity Concentration Guide is applicable
only for the circumstances under which
the use of its corresponding Radiation
Protection Guide is appropriate.
It is recommended that :
6. The Federal agencies, as an interim
measure, use radioactivity concentration
guides which are consistent with the rec-
ommended Radiation Protection Guides.
Where no Radiation Protection Guides
are provided, Federal agencies continue
present practices.
No specific numerical recommenda-
tions for •Radioactivity Concentration
Guides are provided at this time. How-
ever, concentration guides now used by
the agencies appear appropriate OB an
interim basis. Where appropriate radio-
activity concentration guides are not
available, and where Radiation Protec-
tion Guides for specific organs are pro-
vided herein, the latter Guides can be
used by the Federal agencies as a start-
ing point for the derivation of radio-
activity concentration guides applicable
to their particular problems. The Fed-
eral Radiation Council has also initiated
action directed towards the development
of additional Guides for radiation
protection.
It is recommended that:
7. The Federal agencies apply these
Radiation Protection Guides with judg-
ment and discretion, to assure that rea-
sonable probability is achieved in the
attainment of the desired goal of protect-
ing man from the undesirable effects of
radiation. The Guides may be exceeded
only after the Federal agency having
jurisdiction over the matter has carefully
considered the reason for doing so in
light of the recommendations in this
paper.
The Radiation Protection Guides pro-
vide a general framework for the radia-
tion protection requirements. It is
expected that each Federal agency, by
virtue of its immediate knowledge of its
operating problems, will use these Guides
as a basis upon which to develop detailed
standards tailored to meet its particular
requirements. The Council will follow
the activities of the Federal agencies in
this area and will promote the necessary
coordination to achieve an effective
Federal program.
If the foregoing recommendations are
approved by you for the guidance of
Federal agencies in the conduct of their
radiation protection activities, it is fur-
ther recommended that this memoran-
dum be published in the FEDERAL
REGISTER.
ARTHUR S. FLEMMINO,
Chairman,
Federal Radiation Council.
The recommendations numbered "1"
through "7" contained in the above
memorandum are approved for the
guidance of Federal agencies, and the
memorandum shall be published in the
FEDERAL REGISTER.
DWIOHT D. EISENHOWER
MAY 13, 1960.
[F.R. Doe. 60-4539; Filed, May 17. I960;
8:61 a.m.]
G-6
-------
NOTICES
12921
UNDERGROUND MINING OF
URANIUM ORE
Radiation Protection Guidance for
Federal Agencies
On May 25, 1971, the Environmental
Protection Agency published a notice in
the FEDERAL REGISTER (36 P.R. 9480) con-
cerning guidance for the protection of
underground uranium miners. The notice
stated: "The Administrator does not find
a basis for modifying the guidance ap-
proved by the President that an annual
exposure level of 4 WLM be effective as
of July 1, 1971." The notice also stated
that "All interested persons who desire
to submit written comments for consid-
eration in connection with this matter
should send them to the Administrator,
EPA, Washington, B.C. 20460, within 30
days after publication of this notice in
the FEDERAL REGISTER. Comments re-
ceived after that period will be con-
sidered if it is practicable to do so, but
assurance of consideration cannot be
given except as to comments filed within
the period specified."
All written comments received on or
before June 28,1971, have been reviewed.
Letters of comment have been received
from industry, other Government agen-
cies and a labor union. These comments
are available for inspection at EPA
Headquarters, 1626 K Street NW., Wash-
ington, DC 20460.
Several questions were raised on the
scientific basis for setting the guidance
of 4 WLM per year and in particular
challenged the validity of the PHS
epidemiologic report.
The Environmental Protection Agency
has fully considered the methodology of
the PHS epidemiologic study on uranium
miners as well as the limitations of the
study data for the setting of standards
for underground uranium miners.
In addition EPA has evaluated a con-
siderable body of other scientific infor-
mation, both experimental and epidemio-
logic, available on radiation induced lung
cancer for its relevance to establishing
radiation protection guidance for ura-
nium miners. EPA has also taken into
account reports from several expert and
advisory groups1 established to review
and interpret the problem of radiation
induced lung cancer.
"The DHEW review group. May 1567; (2)
KAS/NRC Advisory Committee to PRO 1868;
(3) NAS/NRC Advisory Committee to FKC,
1970/71; (4) Subgroups I-A and I-B or the
Interagency Uranium Mining Radiation Re-
view Group, 1970/71; (5) NCRP Report 39,
1071; and (6) ICRP Publication
Based on the reports of these expert
groups and the other considerations
noted above, EPA concludes that guid-
ance not to exceed 4 WLM per year is
warranted in order to afford adequate
radiation protection of uranium miners.
Furthermore, it is emphasized that the
exposure levels of concern are not "low"
in the context of usual occupational radi-
ation protection practices; an annual
exposure greater than * WLM would
probably result in a dose in rems to the
critical tissue of the lung that exceeds
the occupational radiation standard gen-
erally accepted In the nuclear industry.
Therefore, it has been concluded that
the comments suggesting that EPA
should recommend less stringent radia-
tion protection guidance than the pres-
ent 4 WLM per year do not provide an
adequate basis for doing so. Accordingly,
EPA does not recommend any change in
the guidance approved by the President
and published in the FEDERAL REGISTER
(34 F.R. 576, 35 F.R. 9218) of 4 WLM
per year effective July 1, 1971.
Several comments were received which
referred to the means of implementing
the 4 WLM guidance. As the May 25,
1971, FEDERAL REGISTER notice indicated,
decisions concerning the means of imple-
menting the guidance for uranium mines,
including any procedures for variances
which may be made available to indi-
vidual mining operators, must be made
by the regulatory agencies which adopt
this guidance. It should be noted that
the Secretary of the Interior on June 30,
1971. signed proposed amendments to
regulations under the Federal Metal and
Nonmetallic Mine Safety Act. These pro-
posed amendments relate to variances
applicable to underground uranium
mines.-EPA will provide such comments
as it deems appropriate on these pro-
posed amendments directly to the De-
partment of the Interior at a later date.
Copies of all of the comments which
EPA has received in response to the
May 25, 1971, FEDERAL REGISTER notice
and copies of this FEDERAL REGISTER
notice have been sent to the Secretaries
of the Interior and Labor under cover
of a letter dated July 1, 1971.
Dated: July 1,1971.
WILLIAM D. ROCKELSHAUS,
Administrator.
[FR Doc.71-9697 Filed 7-8-71:8:40 am)
No. 132—Pt. I-
FEOERAl REGISTER, VOL. 36, NO. 132—fRIDAY, JULY 9, 1971
G-7
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