Technical Report
EPA 520/4-78-010
RESPONSE TO COMMENTS:
GUIDANCE ON DOSE LIMITS FOR
PERSONS EXPOSED TO TRANSURANIUM ELEMENTS
IN THE GENERAL ENVIRONMENT
October, 1978
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RADIATION PROGRAMS
CRITERIA AND STANDARDS DIVISION '•
WASHINGTON, D.C. 20460
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CONTENTS
Listing of Respondents to Federal Register Notice. . ...ii
1. Introduc tion .". 1
Revised Text of Guidance Recommendations ... 3
2. Response to Comments - Summary Report
2.1 Basic Guidance and Standards Philosphy ......5
2.2 Risk Associated with the Guidance 12
2.3 Economic Costs Associated with the Guidance......: 25
2.4 Implementation. . . .32
2.5 Biological and Environmental Models 45
2. 6 Miscellaneous Comments 52
3. Response to Comments - Annexes
3.1 Annex 1 ... .... .'. 67
3.2 Annex 2 , .. 75
3.3 Annex 3 100,
3.4 Annex 4 ...... ..... r... ..,..152
3. 5 Annex 5 . 156
3.6 Annex 6. . .. ..172
4. Estimated Costs of Remedial Actions ."......... .179
5. Guidance implementation 199
6. The Dose and Risk to Health due to the Inhalation
and Ingestion of Transuranium Nuclides .207
7. Rocky Flats Facility - Technical Assessment Document 221
8. Discussion of Comments submitted by Carl Johnson, M.D.,
Director of Health, Jefferson County, Colorado..",. . ...--. 267
Annex - Department of Energy Comments on Decontamination Costs
Discussed in the EPA Proposed Guidance on Dose Limits for Persons
Exposed to Transuramium Elements in the General Environment
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LISTING OF RESPONDENTS TO FEDERAL REGISTER NOTICE
1. Tenneco Inc.
2. Colorado Environmental Health
Association
3. Timothy E. Wirth, Congress of the
United States
4. Texas Deptartment of Health
5. Ilene Younghein
6. N.Y. Federation for Safe Energy
7. Natural Resources Defense Council, Inc.
8. Edward A. Kartell
9. Colorado Department of Health
10. Jefferson County Health Department
11. Department of Defense
(Defense Nuclear Agency)
12. Nuclear Safety Associates
13. Department of Energy
14. Conference of Radiation Control
Program Directors
15. Center for Environmental Research
and Development
16. Commonwealth Edison (Chicago, Illinois)
17. Nuclear Regulatory Commision
18. National Council on Radiation Protection
and Measurements
Date Received
13 Dec. 1977
27 Dec. 1977
4 Jan. 1978
24 Jan. 1978
15 Feb. 1978
21 Feb. 1978
27 Feb. 1978
27 Feb. 1978
27 Feb. 1978
1 Mar. 1978
1 Mar. 1978
1 Mar. 1978
6 Mar. 1978
7 Mar. 1978
16 Mar. 1978
24 Mar. 1978
24 Mar. 1978
27 Mar. 1978
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1. INTRODUCTION
The staff of the Office of Radiation Programs has evaluated all
comments received in response to publication of the proposed Federal
Radiation Protection Guidance on Dose Limits for Persons Exposed to
Transuranium Elements in the Environment (Federal Register Vol. 42,
No. 230, pages 60956-9, Nov. 30, 1977). Responses to these comments
are given*in this publication. The Agency concluded that the comments
received did not raise substantive new issues and that, therefore, the
proposed recommendations should be submitted to the President with
only minor changes for promulgation as guidance to all Federal
agencies.
Comments and corresponding staff responses have been grouped,
insofar as possible, by major subject categories. Responses are given
for specific comments as received, and are referred to the text, of the
Summary Report (EPA Publication 520/4-77-016). In a few instances,
comments were very general and not applicable to the,proposed .
Guidance. No staff responses have been provided for these.
New or revised sections for the technical Summary Report document
have been -prepared on a number of different topics. These follow the
Responses to Comments part of this report, and include a section on
the costs of remedial actions (based in large part on information
provided by the Department of Energy and the Nuclear Regulatory
Commission), a revised section on implementation, a discussion of dose
rates and risks from soluble transuranium compounds, an assessment of
potential health risks to persons outside the boundaries of the Rocky
Flats Plant, and a staff analysis of a soil sampling and analysis
method proposed by Carl Johnson, M.D., Director of Health, Jefferson ;
County, Colorado.
, The comments as received by the Agency are not reproduced here in
order to avoid unnecessary duplication. Single copies are available
on request from the Director, Criteria and Standards Division, Office
of Radiation Programs, ANR-460/CM#2, U. S. Environmental Protection
Agency Washington, D. C. 20460. - , •. .
The Agency has made some minor changes in the -wording, of the
Guidance. The revised text of the recommendations follows this
section.
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REVISED TEXT OF GUIDANCE RECOMMENDATIONS
In order to assure the protection of persons in the general
population by limiting the radiation doses that an individual in a
critical segment of the population may receive from concentrations of
transuranium elements present above average background levels in the
general environment, the following recommendations shall apply for the
guidance of Federal agencies:
1. The annual alpha radiation dose rate to members of the
critical segment of the exposed population as the result of exposure
to transuranium elements in the general environment should not exceed
either:
a. 1 millirad per year to the pulmonary lung, or
b. 3 millirad per year to the bone.
2. For newly contaminated areas, the Federal agency responsible
for implementation should take immediate action to minimize both the
residual levels of transuranium elements in the general environment
and the radiation exposure of the general public. Determination and
implementation of appropriate measures to ensure compliance with the
above recommendations should begin as promptly as possible and should
be completed within a reasonable period of time.
3. The recommendations are to be used only as radiation
protection guidance for presently existing cases of environmental
contamination by transuranium elements and for possible future cases
of environmental contamination from unplanned releases of transuranium
elements. They are not to be used by Federal agencies as limits for
planned releases of transuranium elements into the general environment.
DEFINITIONS
"bone" means osseous tissue. The average total weight of this
tissue is assumed to be 5000 grams.
"critical segment of the exposed population" means that group
of persons within the exposed population who, because of residency or
other factors, can on the average be expected to receive the highest
lifetime radiation dose to the pulmonary region of the lung or to the
bone from a specified source of environmental transuranium element
contamination.
"general environment" means the total terrestrial, atmospheric
and aquatic environments outside the boundaries of Federally licensed
facilities or outside the boundaries of sites which are under the
direct control of a Federal agency.
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"millirad per year to the bone" means the dose rate attained
after 70 years of chronic exposure. This dose rate is calculated by
dividing the alpha energy absorbed in the bone during the 70th year by
the bone mass.
"millirad per year to the pulmonary lung" means the equilibrium
dose rate following chronic inhalation. This dose rate is calculated
by dividing the alpha energy absorbed per year in the pulmonary lung
by its mass.
"pulmonary lung" means the region of the lung consisting of
respiratory btonchioles, alveolar ducts, atria, alveoli, and alveolar
sacs. The average total weight of this tissue, including the
capillary blood, is assumed to be 570 gms.
"rad" is the unit of absorbed dose, defined as the energy
imparted to tissue by ionizing radiation divided by the mass of the
tissue. One rad is equal to the absorption of 100 ergs of radiation
energy per gram of matter.
1 millirad (mrad) = 10~3 rad.
"transuranium elements" means all chemical elements with atomic
number greater than that of uranium as classified in the Periodic
Table of Elements.
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2. RESPONSE TO COMMENTS - SUMMARY REPORT
2.1 Basic Guidance and Standards Philosophy
1. Representative Timothy Wirth
I see a need to question the form of the standards themselves.
Currently, the standards are based on the lifetime dose that a person
living in the area would receive. It does not look at the community
wide effect as a whole. I am not sure that this is the correct
approach to take. For example, if the radiation contamination of an
area was such that a person living there had one chance in ten
thousand of getting cancer, but only fifty people lived in the area,
the most likely number of extra cancer cases in the .country as a whole
would be zero as a result of this contamination. If the same
contamination was occurring in Manhattan, there could be thousands of
additional cases. The proposed standards do not address that
problem. But this is the problem that society faces; not the
probability of cancer in a hypothetical person that will result from
radioactive contamination, but rather a probable number of cancer
cases, depending on the population density of the area. Unless we
find cancer in.New York less offensive than cancer in New Mexico, we
must adjust our standards to take into account these population
density differences. The amount of emissions that are acceptable in
Manhattan really is lower than in an unpopulated area.
Thus, I think that the EPA should come up with a standard that
says "this is the number of probable excess cancer deaths that we are
willing to tolerate from a government facility." The actual numerical
standards for any site will then be calculated similarly to your
current approach, but with the added factor of population.
The advantage of this approach i§ obvious. It gives citizens in
all parts of the country equal protection, since cancer deaths are
giv
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numerical risk limit as proposed is not intended to be viewed as an
acceptable limit, but rather is to be interpreted as recommending that
doses to individuals should be kept well below the limit and that
exceeding the guidance values is unacceptable. The maximum risk to an
individual from lifetime exposure to transuranium element
contamination was proposed on the basis of comparisons with other
commonly accepted low probability risks. The appropriateness of such
a proposed risk limit is a subject for social judgment.
Cumulative risks to a large population group were also considered
in the development of the guidance but, because the estimated
population dose commitments for all existing sites were small, the
guidance recommendations were based on the maximum risk to '
individuals. The observation that population-impacts should be
considered in the decision making process is a valid one. However if
one were to limit the total adverse impact at any site to a given
number of fatalities independent.of the population density, then the
guidance would not provide equal protection to persons in all sections
of the country. The Agency has taken this into consideration in its
recommendations concerning future contamination, where it recommends
that remedial action be carried out as soon as possible after
occurrence to a level as low as reasonably achievable and with the
numerical guide as an upper limit. The determination of a level as
low as reasonably achievable would take into account the size of the
population exposed,, the cumulative population dose as well as the
costs of cleanup. Therefore, both the individual and population risk
are integral to the implementation of this guidance. In effect,
therefore, the projected impact of a source in terms of committed
population dose or potential fatalities becomes the primary
consideration in determining the range and scope of remedial actions
within the constraint of assuring that individual dose rates not
exceed the guidance recommendations.
2. Department of Energy
' ) - - i ;
n. . 1* . "It: *s instructive to compare the proposed EPA Guidance
limits with...(those)... recommended by other bodies...On the basis of
these comparisons the- EPA proposed guidance could be considered to be
unnecessarily restrictive."
Staff Response - The comment compares the proposed guides to
upper limiting doses for the general population from all sources
combined as recommended by ICRP, FRC, and NCRP. These groups all
emphasized that the recommended limits were upper bounds; that within
these, doses should be permitted only insofar as they could be
justified and were, in addition, as low as practicable or as low
as reasonably achievable. Too often these recommended limits have
been treated as defining the acceptable range of exposure, (e.g. like
speed limits) and this comment falls into the same error. The
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proposed EPA guides represent instead a judgment of what exposure,
within .these boundsf, is acceptable because it adequately limits the
risk to a critical segment of the population-and. is economically ,, ..-;,v, '.,-
achievable. Disagreement with the proposed guides should be based
upon the validity of EPA judgements on these latter two points, not on
the difference between the proposed guides and the limiting
recommendations of ICRP, FRC and NCRP. '
3. Department of Energy
"The EPA apparently adopts the position that the total
permissible radiation exposure should not be allocated to a single
source or activity. The ICRPj however, considers it quite appropriate
...If the EPA has embarked upon a policy, o£ apportionment...This
should «be clearly presented..." • >
Staff Response - EPA does not take the.position that the general
dose limits are available for apportionment. Neither does the ICRP;
they endorse^instead optimization of dose reduction'from individual
sourcesj irrespective of contributions from other sources'> •
(para. 121, ICRP^26). Since the exposures governed by the proposed
guidance are likely to be chronic, .the even more restrictive ::
considerations of para. 122 and para. 123 of ICRP-26 define •-ICRP1 s
view of suitable, boundary conditions on dose (100 mrem/yr) from all
sources. The question of. apportionment is not germane to choosing an
optimized dose level for radiation protection; it is only pertinent to
situations in which several relatively large doses may accrue to a
single individual from separate sources. That situation does not
appear pertinent- to the doses contemplated as acceptable by the
proposed guidance. ; "
4. Conference of Radiation Control Program Directors
"..it is hoped that EPA will appropriately address the impact of
this standards and guidance on the apportioning of the 170 mrem/year
limit, or its reduced value." .
•;. • •:.• I '-.. .: • '•••' ' '- • ' " - 'I'".' • • -''"' '• • • ••••'•' '"' '" . '
Staff Response - EPA will address this matter .when and if it
appears to be a realistic problem. At this point in time, it appears
highly improbable that the 4 mrem/yr drinking water limit, the 25
mrem/yr uranium fuel, cycle ;limit and, the present proposed guides could
result in combined doses .to a .real individual' s organs which'even \~
approach the sum of these three limits, let alone the ,170 mrem/year
bound or any foreseeable, future .reduction of that limit. :
5. Department of Energy . , . ,
It is not clear how this Guidance'will "offer much greaterv
protection to the vast majority of the population at. lesser risk.'1
This vast majority receives no protection nor does it require any.
(p-15, lines 20-24)
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Staff Response - We do not agree. The proposed guidance
establishes recommendations on an upper limit for exposures to the
critical segment of the population by transuranium elements in the
general environment. By ensuring compliance with these
recommendations, an upper level of risk is established. Because most
members of the general population are exposed to lower doses than the
defined "critical segment," the vast majority of the population is at
lower risk and afforded greater protection.
6. Department of Energy
It would be useful to describe and document the "...different
regulatory requirements, constraints associated with remedial actions
for a particular carcinogen, uncertainties in the calculations,
differences in methods used to derive lifetime risks, and economic
considerations." This would enable the user of this Guidance to
understand the basis for and the considerations involved in this
Guidance. (p-16, lines 18-22)
Staff Response - The content and basis of Federal actions
intended to regulate carcinogens are generally published in the
Federal Register. Because no common basis presently exists for risk
evaluations, and there is no agreement on a level of "acceptable risk"
applicable to all situations, such comparisons do not serve a useful
function. As stated in the rationale for the Guidance, there is a
real distinction between actions intended to achieve a remedial rather
than preventive objective. The best comparison available is with the
contamination of the James River with kepone, but the .health and
economic impacts of the two situations are so different that the
decisions made^for kepone cannot be applied directly to transuranium
element contamination. The public health risks associated with the
transuranium guidance recommendations are generally lower than those
for most other regulated carcinogens.
7. Department of Energy
The sentence on page 16 makes the very important point that the
Guidance is "applicable to remedial and restorative actions, and must
be distinguished from risk levels which provide for a routine level of
acceptability;" but this distinction does not seem to have been
applied in the derivation of the Guidance.
Staff Response - The statement is intended to convey the idea ..
that the level of an "acceptable" risk is generally lower for a
preventive than for a restorative situation. The Agency has not
evaluated the factors which determine the appropriate level of risk
for routine and planned releases.
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8. Department of Energy
Since dose limits are customarily expressed in units of rem, it
seems unusual to find them expressed here in rad. While an effort is
made to justify this in Annex III, many readers may never get to Annex
III and it might be well to show the rem equivalents. If this is
done, the limits become 10 mrem/y to lung and 150 mrem/y to bone. On
such a basis the limit to lung seems much more conservative than the
limit to bone. This may be justified, in part, by the more complete-
information on human bone risk, as discussed in Annex III.
(page 21, lines 3-4)
Staff Response - The rad is the basic unit of absorbed dose for
ionizing radiation, while the rem is a relative unit which modifies
the rad by the "relative biological effectiveness" for the specific
type of radiation. Dose limits are best expressed in rad in order to
avoid the ambiguity introduced by controversy on the "quality factor1'
for alpha radiation in different tissues (see ICRP Publication 26).
In the development of this Guidance, the,comparability of dose rates
to different organs is based on risk.
9. Tenneco Inc.
Shouldn't the absorbed dose be given in terms of the SI derived
unit, the becquerel (Bq)? Similarly, the absorbed dose rate unit .
should be in grays per second (Gys/s).
Staff Response - The Federal Register notice 42:206 pp 56513-4,
published by the Department of Commerce, which defines policy
regarding use of metric units in the United States, states that "in
those cases where their usage is already well established, the use,
for a limited time, of the units (— curie, roentgeri, rad) is
accepted, subject to future review."
10. Ilene Younghein
Much is said in your assessments about economics and practicality
but nothing about suffering. There is the suffering of parents with
abnormal children, the suffering of men, women, children and animals
dying of lung, bone and kidney cancer.
Staff Response - Suffering cannot generally be quantified in, '
monetary terms, but is certainly considered with respect to genetic
defects and cancer mortality. The rationale for the guidance is not
based on any criteria related to the direct or indirect monetary costs
of a human life or to suffering and only uses economic analyses to the
extent necessary to show that compliance is feasible.
11. Ilene Younghein '
Let me comment on the report itself. One, it is
nameless-therefore blameless. It appears to be a whitewash, in trying
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to live with the mess we already have, and it certainly doesn't
accurately access your previous hearings. Most of the reports are
either middle of the road or downplay the dangers of plutonium.
Reports by such scientists as Samuel Milham, Thomas Mancuso, Irvin
Bross, Karl Morgan, John Gofman and Arthur Tamplin were not included.
Edward^Martell, who has done extensive research or problems with
plutonium at Rocky Flats, didn't make the list either. I always want
to know who writes the reports, their positions, and possible
conflicts of interests.
Staff Response - The proposed Guidance was prepared by the staff
of the Office of Radiation Programs and published after review by the
Administrator of EPA. It therefore represents an Agency viewpoint
rather than that of individuals.
The Agency staff is thoroughly familiar with the published
reports of the scientists named and has considered their results in
preparation of the Guidance to the extent appropriate.
12. Ilene Younghein
In Annex 1, p.9 you say "large areas outside the exclusion areas
have become contaminated with plutonium". Compared to the age of the
earth, the last thirty years would be similar to a grain of sand on a
beach. At the risk of discussing ethics, I find it highly immoral
that in the last few years we have permanently contaminated portions
of this earth - something that hasn't happened in the billions of
years previously. Is this being weighed in your radiation standards
and your environmental impact statements?
Staff Response - No. The ethical aspects of releases of
transuranium elements to the environment were not considered in
developing the guidance recommendations.
13. Jefferson County Health Department
I am concerned with the criteria on page 60957 in the first
paragraph, Rationale for Guidance. One of two primary criteria used
in developing this guidance, "That any actions required by
implementation of the guidance be practical in terms of overall
economic requirements". In view of the nature of the guidance
proposed, I feel that economic concerns have really been given
foremost consideration, perhaps with intent to minimize any economic
impact^on federal agencies or private corporations which have
contaminated offsite lands. It appears to me that the concern for the
public health has been given lower priority here.
Staff Response - The order of application of the criteria has
been reversed in this comment. The risk to an individual in the
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critical segment of the population is the primary concern of the
guidance. Implementation was deemed to be practical in terms of
overall economic requirements.
14. Jefferson County Health Department
I feel that the estimates in this proposed guidance of deaths due
to cancer, the effects on longevity, and the genetic-effects cannot be'
conservative estimates. As an illustration of the present federal
nonr-conservative policy in regulating radiation exposure, consider the
recent report of a significant increase in chromosome abnormalities in
plutonium (workers) permitted by federal radiation protection guides-.
The current radiation protection guides are simply too high to provide
adequate protection. I disagree with the report in that "realistic"
estimates must be made where there is insufficient knowledge. Our
experience with radiation hazards over the past fifty years should •
teach us that we must be prudent in evaluating radiation hazards and
that we must be conservative in establishing radiation protection
guides. '-• .„., ':
. Staff Response ~ The Agency staff's estimates of,the relationship
between radiation dose and cancer mortality and serious genetic
effects are not intended to be conservative but rather to be realistic
estimates based on best available data. The degree Of conservatism •"
can only be established by comparison with such realistic estimates,
and is here based on introducing an "adequate margin of safety" in the
recommended dose rate limit for the "critical segment of the
population". On the basis of public comments received by the Agency,
we believe the judgment with respect to the dose rate limit and
associated maximum risk to an individual to be reasonable; •>, .'
The staff does not believe that previous Federal Guidance on
occupational expsoure has a bearing on guidance levels for
transuranium elements in the general environment. ' "-'\
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2.2 Risk Associated with Guidance
1. Department of Energy
The dose limits of the Proposed Guidance are as low as they are
for several reasons. The EPA assumed an acceptable level of risk of
slightly less than 10~6 per year. The ICRP (Publication 26) assumed
an acceptable level of risk in the range of 10~5 to 10~6 per year,
and established its "individual member of the public" limit at a level
estimated to be equivalent to a risk of 5 x 1(T5 per year, assuming
that the average exposure will not exceed 10% of the limit. This
single factor of about 50 is enhanced in the case of lung by an EPA
factor relating lung dose and cancer risk that is larger than the
corresponding ICRP factor, but is largely cancelled in the case of
bone by an EPA dose-risk factor smaller than the ICRP factor.
Staff Response - EPA has not assumed an '"acceptable" level of
risk. The Agency recognizes that the stated level of unacceptable
risk, i.e. greater than 10~6 per year, is about the same as the
lowest value given in ICRP Publication 26, and that there are some
differences in factors assigned to risk conversions from those
reported in ICRP-26. In view of the fact that the ICRP system of dose
limits applies to the doses received from a variety of sources, and
not a single source such as dealt with by EPA, the differences are
considered reasonable for the environmental problems currently faced.
2. Conference of Radiation Control Program Directors
The text of the proposed guidance was developed using widely
accepted procedures in ascertaining radiation doses and dose rates and
the related health risk. The level of acceptable risk has been used
before; however, not to the extent used in this document. The level
of risk deemed acceptable by EPA in this guidance appears to be
arbitrary in view of the levels of transuranics in the general
environment. Stronger wording than that provided in the text of the
guidance must be provided to the effect that the "levels must be as
low as reasonably achievable with available technology". This would
provide for the use of lower level standards where the situation would
allow, i.e. Colorado. It is also a reasonably conservative approach
for the implementation of the guidance as it is finally adopted.
Staff Response - The EPA staff has not assumed an "acceptable"
level of risk. The recommended maximum risk of 10~6 is judged by
the Agency to be such that any risk significantly greater would be
unwarranted and therefore unacceptable. Such determinations must rely
on judgments, since no means exist for deriving an "acceptable" level
of risk for non-threshold pollutants. The Agency does not believe
that the stated level of risk is large; it is certainly comparable
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with risks associated with many other pollutants and food additives
which are believed to be carcinogenic. In practice, it is anticipated
that no person will be exposed to the limiting risk but that exposures
will be.at levels substantially lower, even for those f&w individuals
in the critical segment of the population.
3. National Council on Radiation Protection and Measurements
The derivation of the risk values used in setting these limits is
poorly explained. Comparison is made between real risks that involve
large numbers of people with hypothetical risks that involve only a
small part of the population.
We recommend that the derivation of this risk of 10 x 10~5 per
lifetime be reexamined and justified on the basis of the population
size, uncertainty in the value,, economic costs, environmental cpsts,
and human costs.
Staff Response - The Agency staff has not made a distinction
between "real" risks and "hypothetical" risks. The population dose
has not been used as a rationale for the guidance levels; rather, the
guidance levels were based on judgment with respect to the level of
risks to individuals.
The factors suggested in this comment have been considered with
respect to the lifetime risk associated with the guidance levels.
Population size is not included because risk takers (with respect to
this guidance) can be individually identified and the Agency has? the
responsibility of protecting these individuals. Uncertainties in risk
estimates are recognized, but they were not judged so large as to
prevent the issuance of guidance. Costs (economic, environmental and
human) were not directly part of the guidance rationale, but were
considered to the extent necessary to show that the guidance could be
implemented. -
4. Colorado Department of Health
While the risk associated with proposed guidance appeared to be
well below other risks experienced by the general population as
depicted by Annex IV, if the situation can be controlled then this
must be done, i.e., as low as reasonably achievable by available
technology. Therefore, if the State of Colorado can justify that
their more conservative standard is reasonable for the situation that
currently exists within the State, then that standard or lower
achievable levels must be applied. Depending on the method of
comparison, the current Colorado standard for Plutonium-in-Soil is a,
factor of 70 •*• to 150 times lower or more conservative than the
proposed EPA guidance.
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Staff Response - EPA believes that the practice of reducing
exposure to levels "as low as reasonably achievable" in accord with
the long existing practice in radiation protection has merit and is to
be encouraged. The State of Colorado may be able to establish more
stringent requirements than Federal Guidance if it so desires
Federal guidance is only directed to the Federal agencies and'their
programs to assure the health and safety of the public.
Comparisons between the Federal Guidance and the Colorado
standard are inappropriate because they have an entirely different
objective and specify different implementation procedures. The
a0i^n°-Stand^rd " intend?d to Protect construction workers and sets
a plutonium soil concentration level which, if exceeded, requires that
special protective actions be considered. The Federal Guidance, on
the other hand, designates a dose rate to persons in the general
population which serves as a limit for exposure to transuranium
elements in the general environment. The Colorado standard and the
Federal Radiation Guidance therefore can be viewed as complementary
and serving different purposes. cucaty
5.
Center for Environmental Research and Development
I urge you to publicize widely what exactly it is you are
proposing. You are proposing to allow polluters to ignore alpha
activity below 4400 dpm/100 Cm2 background in all the situations
described in EPA 520/4-77-016. However, you present considerable
evidence that background is 40 dmp/100 cm2 or perhaps
4 dmp/100 cm* (for example, pags. 3, 5; Annex 1, pgs, 3, 4, 5)
Thus the contamination you are proposing to allow is higher than
background by a factor of from 100 to 1000. On the face of it
terming such levels of contamination "acceptable" is a travestv of
environmental protection. "
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6. Tenneco
.- '. " - • . - >-.' .''.:'.- •&'• • ,
I agree with the concept of looking at acceptable risk rather
than.taking the; approach that no exposure is to be allowed because
someone may contract a disease and die. I personally .believe that
such "lowest feasible level" controls are doomed to extinction because
of the realities of life. There are finite risks .associated with all
human endeavors. Cigarette smokers and seat belt non-users certainly
seem to comfirm that people are willing to accept risks. . I should
hope that statutory standards consider the "big picture" when.levels
are set that may become infeasible,.due to real economic, considerations'.
Staff Response - The agency staff agrees with this;comment, to
the extent of recognizing that mandating of a zero risk concept is
inappropriate and not feasible. However, it believes that government
has an obligation to its citizens to provide maximum protection of
health, safety, and welfare within the constraints of economic and
social considerations.
7. Jefferson County Health Department
In the second paragraph under Rationale for Guidance, reference
is made to the exposure of all persons to "a large number of competing
risks", which implies somehow that because of other risks to health
that the risk of health from radiation is made somehow;,acceptable.
I believe that the expression "competing risk" is used
inappropriately on page fifteen (2nd paragraph), and elsewhere. , The, :
use of the expression here implies that radiation exposure is not very
important because of .other "competing risk". I think we must consider
all risks to health as additive or perhaps potentiating rather than ,
"competing" i.e., asbestos workers and uranium miners who also smoke
cigarettes have much more severe effects than merely adding risk
factors together. The term "competing risks" implies that one adverse
effect somehow ameliorates another adverse effect.
Staff Response - The comment misinterprets the use of the term
"competing risks" if it implies that this has. been used to make the
radiation risk acceptable. The term "competing risks", as used here,
expresses the fact that all persons are continuously subjected to a
large number of risks that compete for the deaths of all individuals.
The removal of any one of these competing risks (e.g. heart disease)
results in an increased risk of death from other causes of death- .The
introduction of a new cause of death (e.g. exposure to transuranium
elements) reduces the number of deaths from other causes, but at the
same time other causes of death will take the lives of some of the
individuals otherwise destined to die of the new cause of death (in
this case, exposure to transuranium elements), thereby reducing its
apparent risk. The intent of the calculation of competing risk jLs to
give the reader some perspective on the magnitude of the additional
risk of death to an individual from exposure to transuranium elements
at the guidance limit.
IS
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8. Jefferson County Health Department
It must be noted that the proposed annual alpha radiation dose
rate to the public living in such contaminated areas (one millirad per
year to the pulmonary lung or three millirad per year to bone) will
result, on the basis of animal studies, in 20 millirem to lung, 960
millirem to trachiobronchial lymph nodes, 60 millirem to bone, 20
millirem to liver, 4 millirem to the kidney and one millirem to
gonads. These may be contrasted with the radiation dosage limits
established by the 1976 EPA Water Regulations which limit the exposure
of the general public to no more than 4 millirem per year from
man-made beta and photon emitters". A millirem is a term developed
to consider biological effectiveness and organ distribution of
different types of radiation, and make them comparable in terms of
health effects. As you can see there is a marked discrepancy between
the proposed guidance levels and the regulations promulgated last year.
I am puzzled at the non-conservative guidance proposed by the
EPA. I thought the maximum radiation levels established by the EPA
Water Regulations were commendable and well-supported, and reflected
concern for public health. This is not true of the proposed
guidelines.
Staff Response - The basis and rationale of the EPA Drinking
Water Regulations and the Guidance for Transuranium Elements are
entirely different and not comparable. The four millirem annual limit
in the Drinking Water Regulations is given as the maximum contaminant
level only for man-made beta and photon-emitters in finished drinking
water. The biological risk from alpha emitters differs markedly, so
that a direct comparison in terms of absorbed dose is not
appropriate. The Drinking Water Regulations specify a limit of 15
pCi/liter of gross alpha contamination which, at an intake of 2
liters/day, is equal to 1.1 x 104 pCi/year. For soluble
transuranium elements, where a transfer fraction of 1 x 10~3 is
conservatively assumed, this intake can be equated to about 0 5
mrad/year to bone. Noting the fact that drinking water represents a
single ingestion pathway while the proposed guides refer to food,
water, and inhalation, the limiting dose rates for the Drinking Water
Regulation and the Guidance for Transuranium Elements are comparable
with respect to the risk to the individual.
9- Jefferson County Health Department
I disagree with the third paragraph under Rationale for Guidance
in^that I believe the estimated risk is understated, that is, in my
opinion considerably more than a hundred cases of cancer per million
would occur as a result of exposure to the proposed guidance level.
The guidance acknowledges this in part by saying "It must be
recognized that these estimates are not precise, and have an
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uncertainty of at least a factor of three for cancer risks". I
believe we must allow for these "uncertainty factors" and establish
lower guidance levels than have been proposed. In the first paragraph
on page 60958 the guidance states "Additional risks may result from
transiocation of a small fraction of the transuranium elements in the
lung to other body organs, especially to the liver and bone".
Research with animals indicates that much more than a "small fraction"
of plutonium retained in the lung is translocated to the bone. In the
same paragraph, reference is made to hypothetical cohort of 100,000
persons receiving an annual average dose rate to pulmonary tissue of
one millirad per year per person, which could potentially result in
ten premature cancer deaths, or a hundred premature cancer deaths per
million. Birth defects and general adverse effects-on health due to
chromosomal damage must also be considered.
The proposed guidance level of 3 millirads to bone is estimated
to "potentially result in less than six premature deaths from such
cancers per 100,000" (or 60 deaths per million). However, this
estimate is particulary controversial since estimates of such effects
vary widely. In the third paragraph on this page, concerning genetic
damage, the guidance states that at the guidance level dose to 20
genetic defects would be produced per 100,000 live births (10 ,to 200
genetic defects per million) in the first generation. However, we
must also consider the cumulative genetic defects produced for all
generations as a result of such an exposure. The fact that there
already is a significant rate of genetic defects does not make an
additional increment more acceptable.
Staff Response - The rationale for the guidance is based on the
staff's technical evaluations. The numerical estimates of lifetime
risk represent best judgments with aJ stated range of estimated
uncertainty. Additional risks resulting from transiocation to other
organs, including bone, were included in the total risk to an
individual. First generation and subsequent generation genetic risks
for continuing exposure of both parents at the guidance limits are
given in the technical documents. The staff does not believe that .
risk estimates have been underestimated.
The guidance rationale considered serious genetic effects as
expressed within ten generations from the individual exposure; all of
the additional future generations do not add significant numbers
serious genetic effects in comparison. The agency has not and cannot
make a judgment with respect to an "acceptable" rate of serious
genetic effects that would be committed by the guidance
recommendations.
17
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10. Jefferson County Health Department
It seems quite likely that releases of radioactive materials from.-
the plant have already made some measurable impact on the health of
populations so exposed. An examination of death certificates of
residents dying in 1975 in eight census tracts in south end of the
county, showed a significant increase in deaths from leukemia in the
areas near the plant site. In addition, examination of death
certificates shows an increase in age-specific death rates from lung
cancer. Estimates of risk to health have been published in the
Proceedings of the IVth International Congress of the International
Radiation Protection Association.
Staff Response - The agency staff does not believe that
epidemiological studies have shown an increase in risk to individuals
living in the vicinity of the Rocky Flats Plant. See comment 11 in
Section 3.3
11. Jefferson County Health Department
I am puzzled that the risk of the proposed guidance level (page
15) was less than one chance per million per year, and less than ten
per hundred thousand per lifetime. Why not be consistent and say,
"less than one chance per million per year and less than one hundred
per million in a lifetime?" It is obvious that these risk estimates
are not precise, and for that reason I would prefer to see a range of
risk estimates given as has been customary in the literature.
Staff Response - The lifetime risk of death by specific cause for
members of a cohort is generally given in numbers per hundred
thousand. The annual risk for an individual can be given in any
desired unit — number per million was chosen to avoid values less
than one. An estimate of the range of uncertainty is provided.
12. Nuclear Safety Associates .
It is recommended that the EPA examine the regulations and
practices of other Federal Agencies to determine permitted levels of
public health risk associated with carcinogens and other hazardous
substances the other agencies regulate. The findings should be
considered in the interpretation of dose limits associated with
transuranium elements in the environment.
I ... -.. ^ . •.,
It is .recommended that regulatory limits which the Agency may .,.
develop for transuranium in the environment be consistent in
associated public risks with regulatory limits for other -
non-radioactive substances in the environment that the Agency '..,
regulates.
The supporting document does not reflect the broad perspective
needed to promote consistency and reduce the misapplication of
resources.
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Staff Response— The Agency recognises that -consistency in
regulatory actions based on a limiting risk to individuals or
population groups-is both desirable and necessary. However, the
societal judgment on level of acceptable risk for the many known
and/or suspected carcinogens differs greatly and is based largely on
the perceived balancing of costs and benefits for each material-or
situation. The decision-making process must recognize these
differences. Therefore, consistency in-regulatory actions does not
necessarily require same numerical risk limit for each 'carcinogen, but
rather a consideration-of the level of risk acceptable to society.
13. Department of Energy
It would ^be help'ful if the terms "risk level" and "cancer risk"
were clarified. Cancer risk could refer to (a) contracting a cancer
of any kind,- (b) dying of cancer, or :(:c) something else. (p-16)
Staff Response - All of the numerical risk estimates are for
cancer mortality. The difference, between mortality,'and cancer,
incidence is not significant for the cancers considered.
•--•-' ' . * -• 5 " " . • •
14.-• Department of Energy i:
-Justification of the risk level chosen is not adequate and
provides no convincing comparisons with other risks of life, '
particularly those risks which involve 'a comparatively few people.:
The examples o£ saccharin and kepone seem inappropriate because a much
larger population is involved. (p-16)
Staff Response - As evidenced by the comments received ;-by the
Agency, it is probably impossible to choose'-a single'level of risk, or
to provide a justification for a chosen level, which is acceptable to
all persons in a given population. Such decisions represent a social*
judgment and cannot be made solely by a regulatory agency. The
principal rationale for the guidance value.Is "-that adequate protection
be provided to individuals in a critical segment of the population and
that all other persons be at a smaller risk. Comparisons with other
risks to life, while not exactly equivalent, are the best available.
See also response to comment, 12. ' ....
15. Department of Defense
Risk Perspectives: This entire section takes liberties with the
true situation.- The'estimation of, risk is based on data obtained at
high dose rates extrapolated to low-levels-conditions and has many ;
assumptions. This should be stated initially-and then followed with
what EPA has determined- to be "the risk.- The succeeding aiinex can go '
into detail, (p-24) " . "
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Staff Response - The views of the staff with respect to the
linear, non-threshold hypothesis of risk from radiation are analogous
to those of the National Committee on Radiological Protection and
Measurements (NCRP) and of the International Commission on Radiation
Protection (ICRP).
16. Department of Energy
The limits specified seem excessively conservative, in
particular, the limit for lung. If 25 mrem per year is acceptable for
critical populations exposed to releases from uranium fuel cycle
facilities (40 CFR 190), it does not seem reasonable to restrict lung
exposure from environmental transuranics to 10 mrem (1 mrad). In
fact, an exposure limit considerably higher than the 40 CFR 190 limit
would seem reasonable in view of the lesser probability of exposure to
transuranics, and the smaller populations likely to be so exposed.
(p-21, lines 3-4)
Staff Response - The intent of the Agency is to reduce all
radiation exposures to levels as low as practicable. For the uranium
fuel cycle standard, this was done by considering the cost of reducing
risks. For the proposed plutonium guidance, the limit is based on an
Agency judgment with respect to what would be an unacceptable level of
risk to an individual. It is not appropriate to compare standards or
guides based on such different rationales.
17. Department of Energy
This section should be prefaced by a statement emphasizing the
highly uncertain, and probably maximizing, assumptions involved in
extrapolating radiation risk estimates derived from data obtained at
high dose levels to the very low dose levels considered in this
guidance. This point is now made very inconspicuously in a phrase
attached to an unrelated sentence near the end of this section (p. 27,
line 23).
Staff Response - We agree that there is an uncertainty associated
with risk assumptions, but do not agree that the assumptions
necessarily maximize the estimated risk
18. Department of Energy
This description of risk applies to very insoluble 239puQ2
and not, as stated, to transuranics generally, (p-25, lines 4-16)
Staff Response - The risks are related to dose rates for the
specified organs and are applicable to all alpha emitting
radionuclides.
20
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10
19. Ilene Younghein
Comparing death rates from plutonium to those from chicken pox,
snake bites and saccharin is pure hype. Society is not necessarily
locked into chicken pox or saccharin or rattlesnakes for thousands of
years hence. The risks from saccharin could stop tomorrow, but with
the terribly toxic transuranics, there is no way of stopping its
deadly emissions. The same particle of plutonium that might kill me
could also kill another poor soul in the year 2978.
Staff Response - The data were provided to give some
understanding of the comparative risks involved in terms of present
day human diseases and activities.
20. Ilene Younghein
The proposed standards of 1 millirad to lung tissue and 3
millirad to bone seem high to me in light of the persistent nature of
the transuranics in the environment-especially plutonium 239.'
Staff Response - The comment on the proposed risk level is
acknowledged.
21. Ilene Younghein
Transuranic elements accumulate in the environment from falloutj
accidents, and releases from nuclear facilities. I find Table A 1-3
worrisome. Cumulative deposits went from 0 (uCi/rn^) in the early
40s to 0.00007 (uCi/m2) in 1954 and built up to almost 0.003
microcuries per square meter of plutonium 239 in N.Y. City in 1975.
It seems that every time it rains it rains radiation from heaven.
Whether that radiation comes from Russian or Chinese or Indian or our
bomb testing, or our abortive satellite that broke up over the Indian
Ocean and released over two pounds of Pu-238 to the atmosphere, or the
recent Soviet mishaps that sent their satellite down in Canada,
spewing debris and eventually fallout. Add to that the fires arid
releases from Rocky Flats, the leaks of Pu at Mound Labs and Hariford,
the buildup of plutonium along the coast near the Windscale Plant in
England and the leaking drums off the coast of San Francisco, the
contaminated islands of the South Pacific, the accidents and material
unaccounted for at Apollo and at Crescent and you have a sobering
picture, indeed. How can we safety handle increasing amounts of the
transuranium elements when we have done such a miserable job so far?
Staff Response - The question is philosophical and beyond the
scope of the guidance. The intent of the guidance is to assure
protection of public health from existing and future transuranium
element contamination.
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11
22. Ilene Younghein
Your charts on the death rates from plutonium are not as clear as
the one you did on Background Radiation on page 9. You have divided
your statistics between Pu-239, and transuranium elements, lung, liver
and bone cancer, inhaled and ingested plutonium, so it is hard, if not
impossible to compare the statistics on plutonium and the transuranics
of the 1 millirad to lungs arid 3 millrad to bone, with your charts on
background radiation. What is the expected death rate from all causes
on the inhalation and ingestion of transuranium elements per 100,000
people at the dose allowable by your proposed standards. If the
environment becomes contaminated to your allowable levels, how many
deaths do you project over the radioactive life of these
elements-about 250,000 years for Pu 239? With the projected increase
in nuclear plants, breeder reactors, reprocessing, and the
proliferation of nuclear power and weapons worldwide, the levels of .
plutonium in the environment will be increasing steadily. Allowable
releases may be small, but the e'ffects of accidents or raising levels
of contamination cannot be dismissed.
Staff Response - The consequences considered in risk evaluations
for the guidance include all types of cancer or incidence of serious
genetic defects. The risk levels as stated are for lifetime exposure
of an individual at the maximum dose rate. It is deemed very, unlikely
that the entire country could become contaminated to the guidance
limits, and it is not possible to project cumulative population
impacts over 250,000 years because of the very considerable
uncertainties involved. Evidence to date indicates that the plutonium
deposited on the soil sufaces becomes less available for uptake by man
with time. Long-term projections in terms of geological time scales
are inappropriate and of little use.
23. Ilene Younghein
According to the Tri-State radiation study conducted at the
Roswell Cancer Institute in Buffalo, N.Y., radiation can cause health
effects other than cancers, such as asthma, allergies and other health
problems. There may be risks from plutonium in other categories than
genetic and carcinogens.
Staff Response - The results quoted are largely speculative and
not supported by adequate analyses. The risks discussed in the
technical summary documents are those for which a reasonable
correlation can be established.
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12
24. Ilene Younghein
The.statement in section 3.2 p.27 "therefore, the calculated
risks may be overstated, and no deaths from exposure to transuranium
elements in the environment have been identified" is irresponsible. .
Edward Gleason, a trucker, died after his arm became contaminated with
plutoriium spilleii from a container. Workers at Harford and Rocky
Flats show5a higher than normal incidence of cancer and leukemia.
Cancer rates in this country have been climbing at a rate of 2.2% a
year. Could not a percentage of these cancers be due to the buildup .
of plutonium in our air, soil and water? (p-27) ' .
Staff Response - The statement in Section 3.2 refers only to
risks to the.general population from existing contamination levels,
makes no reference to occupational exposures, and is believed to be an
accurate evaluation of the situation as of today. If the linear
non-threshold hypothesis of radiation damage were carried to the
extremely low levels resulting from worldwide fallout, one to two
additional deaths per year on a statistical basis would be predicted
for the entire U.S. population from this cause. Such small variations
cannot be detected or verified, and would represent an infinitesimally
small fraction of ail cancer deaths.
25. Nuclear Safety Associates
Interpretation of the maximally acceptable, risk imposed on a
member of the public is essential to the selection of dose limits
stated' in the proposed guidance. Yet the supporting document, EPA.
520/4-77-16, reflects superficial consideration of risjt acceptability
and therefore inadequate support for the proposed dose limits. For
example, the only comparison with other EPA guidance was a mention of
the cancer risk associated with the action level for kepone in fish
(no mention of non-carcinogenic effects on health). The only
comparison with another Federal agency was an FDA risk estimate for
saccharin consumption and a definition of a lifetime risk of one per
million as "virtually safe." Only a few of the risks of death
experienced in the US population as a result of other causes were
presented for comparison with the risks associated with the chosen
dose rate limits for TRU; by comparison, the estimated risk associated
with the dose rate limits for TRU is low. It is thus evident that
support for the selection of a maximum acceptable risk to a member of
the public was inadequate, or, at least, inadequately documented * It
is recommended that firm bases interpreting the maximum acceptable
risk be developed before corresponding dose limits are selected.
In view of the relevance which the EPA purported to attach to
uniformity and overall perspective in the determination of a maximum
acceptable risk to a member of the public, it seems reasonable to
request that EPA demonstrate adherence to that philosophy in this
proceeding.
Staff Response -See response to comment 14.
£3
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13
26. Colorado Environmental Health Association
Johnson (1977) in a paper presented to the Annual American Public
Health Association has reported increased leukemia death rates in the
eight census tracts nearest Rocky Flats as compared to nineteen census
tracts located in southern Jefferson County. These death rates range
from 2 to 3 times the rates from southern Jefferson County. The
census tracts nearest Rocky Flats range from 3 to 33 mCi/km2 or
0.003 to 0.033 uCi/m2 in plutonium contamination of the soil. The
proposed guideline of 0.2 uCi/m2 is from 6 to 66 times the level
associated with increased leukemia rates according to the study.
Staff Response - The agency has not accepted Dr. Johnson's report
as a valid epidemiological study. See response to comments 10 and 11
in Section 3.3
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2-3 Economic Cost Associated with the Guidance
1. Department of Defense
Is $500 the cost for estimating the cost to do restorative
actions or is it the cost for doing restoration as implied in Annex VI?
(p-17, line 17)
Staff Response - $500 is stated as the minimum cost for remedial
actions, (see also response to comment 4).
2. Department of Defense
There is no basis for concluding that costs of implementing the
guidance at the reference level would be reasonable and achievable,
particularly in view of proceeding discussion concerning the fact that
costs vary "by location, contamination level, and other factors" and
^...that there are large uncertainties associated with both the areas
involved and in the estimates of costs." This whole presentation is
subjective if not speculative and in a document of this type,
objectivity and specificity should prevail. (p-18, line 7)
Staff Response - The costs of implementing the guidance have been
reviewed and are disscussed in Section 4. (see also response to
comment 6).
3. Department of Energy
It is not clear what "changes by factor of ten" refers to;
certainly not to the precision of the calculations, which seems to be
implied. Some of the factors involved in the calculation of cost
estimates may be uncertainly a factor of ten, but the cost estimates
should be much better than the basis on which the Guidance itself is
established. This should be clarified. (p-17, lines 10-12)
Staff Response - The statement refers to soil contamination
levels. We do not understand the meaning of the comment "cost
estimates should be much better than the basis on which the Guidance
itself is established."
4. Department of Energy
This sentence is not clear. It reads as if $500 per acre is the
cost of just estimating costs associated with remedial action. This
might very well be true, but is not the meaning intended. A total
cost for remedial action of $500 per acre is such an unrealistically
low estimate as to be grossly misleading. It includes only the
25
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monetary costs of the simplest cleanup options, with no consideration
of environmental costs, societal costs or cleanup risks. Certainly it
cannot be reasonably assumed that a "minimum cost" will be applicable
to all (or even any) areas which might require cleanup.
(p-17, line 17-19)
Staff Response - The purpose of introducing a minimum cost
estimate of $500 per acre appears to be misunderstood in this
comment. The intent of the staff was to show that, even for such an
unrealistically low unit cost, the total costs of implementation would'
very rapidly become prohibitively large if the guidance
recommendations were further lowered below the proposed values. This
conclusion is based on estimates of areas which exceed certain soil
contamination levels relative to the soil "screening level" for the
proposed guidance (see Table 2.1). Actual costs of remedial actions
are likely to exceed such a minimum value and will be substantially
greater in most instances. Societal and environmental costs, while
ordinarily not quantifiable in monetary terms, would further add to
the total costs.
5. Department of Energy
For a given area, cleanup costs are apt to be largely fixed
costs, which will not "necessarily increase as the difference between
the existing contamination levels and those sought becomes greater."
(p-17, lines 21-23)
Staff Response - The costs of remedial actions are necessarily
speculative and will need to be determined on a site-specific basis.
The stated minimum cost probably consists primarily of fixed costs,
which become a progressively smaller fraction of the total cost as the
scope and magnitude of remedial actions increases.
6. Department of Energy
How can it be "concluded that the costs...would be reasonable and
achievable," when it is acknowledged in the previous sentence that
"large uncertainties (are) involved?" Actually, the estimated costs
are too low by a factor of 3 as compared to DOE estimates for the same
treatment, and by at least an order of magnitude for any treatment
consistent with the Guidance. Furthermore, the costs considered were
only monetary costs. No consideration is given to environmental costs
or the potential risks involved in cleanup and disposal. Also, the
consideration of costs has been limited to sites of existing
contamination, although the Guidance is also applicable to future
contamination. Consideration should be given to the probable costs
associated with possible future accidents, (p-18)
Staff Response - The conclusion that the costs of implementing
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the guidance for existing sites would be "reasonable and achievable"
is based on an evaluation of the data on .environmental contamination
levels for these sites, which indicate that the sizes of areas which
may require remedial actions at the proposed guidance levels are, all
relatively small. Therefore, regardless of the cost of remedial
actions per unit area, the total costs are expected to be consistent
with the objectives of the guidance. '.
Consideration of environmental costs and of potential risks, is an
integral part of the decision making process, and must be addressed in
implementation of the guidance recommendations. Alternative actions,,
such as restricted occupancy or use of lands, are available where soil-
disturbance or removal are either impracticable or detrimental, on a
long-term basis. The staff believes that the flexibility of,the means
for implementation offered by ,.the Federal Radiation .Guidance r:
procedures, and the common sense of local and Federal officials, would
make it possible to minimize the social and environmental costs
effectively. • -
A more detailed discussion of costs as applied to remedial
actions at both existing and future sites of contamination is given in
Section 4.
7. Department of Energy , -.,•• ••.--•
These numerical estimates of cleanup costs, by employing an ' :
unrealistic figure of $500/acre, and by ignoring environmental costs,
lead the reader to the erroneous conclusion that great benefits can be
obtained in the vicinity of Rocky Flats by the expenditure of only • ,
$100K or $500K. Even with more realistic cost estimates., this table
seems inappropriate for the Summary Report because of the^extensive
further discussion required for its proper consideration. , ,
"Less than" signs are not used consistently. If areas are "less
than," corresponding costs should also be "less than." Actually, a
"less than" value in a table such as this has little meaning since the
reader has no idea of "how much less than." ; , ,
It does not appear reasonable that a decrease in reference level
by a factor of 3 would increase the area involved from1 zero to • -•:••••.
80 nu.2 at the Nevada Test Site or from zero to 20 mi^ at Trinity
Site. This implies a degree of uniformity in contamination level, that
is difficult to believe. (p-19, Table 2.1) .
Staff^Response - The comment implies that.EPA considers a • .
reduction by a factor of three or ten below the. Guidance , ,..
recommendation as conferring a "great benefit." This is not correct,
and the costs of such further lowering of the recommended dose limits
would have.to be balanced against the very small additional gain .in
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public health protection. Even if it were assumed that the cost of
remedial actions was as low as $500/acre, a further reduction is not
warranted for the Rocky Flats Plant and the cost of averting one
additional fatality would be at least several million dollars.
Areas of contamination represent best estimates. Data were
derived from published contour maps prepared by the Department of
Energy or its predecessors. Uniformity of contamination within
contour intervals must be assumed in the absence of more definitive
information.
8. Department of Energy
To the extent that costs of implementing the Guidance were
considered in arriving at an acceptable level of risk, this level has
most certainly been biased in the direction of an unjustifiable
smaller risk. This is because the estimate of cost employed, $500 per
acre, is an unreasonable monetary estimate low by a factor of 3 as
compared to DOE estimates for the same treatment, and by at least an
order of magnitude for any treatment consistent with the Guidance),
and because it includes no consideration of non-monetary societal and
environmental costs.
Staff Response - The costs of $500 per acre was assumed to be a
minimum cost. It was intended to be used to demonstrate that, even if
costs of remedial action were this low, the costs of proposing a dose
limit that established a soil limit below 0.2 uCi/m^ would be
prohibitive. The $500 per acre cost was not used to establish an
acceptable level of risk.
9. Department of Energy
One of the "two primary criteria used in determining the guidance
recommendations..." was "...that implementation of the guidance be
feasible in terms of overall economic impacts." (Summary Report,
p. 14). It is further noted on p.30 that "Monetary costs,
environmental costs, and other non-monetary costs should all be
considered in the evaluation of each alternative combination of
possible remedial actions". From these statements one might
anticipate that a considerable portion of the justification and
explanation of the Guidance would consist of detailed analyses of the
costs of required remedial actions. Such, however, is not the case.
Two pages of generalities are devoted to "Costs of Remedial Actions"
in Annex 5, and a single page plus table are devoted to the same
subject in Annex VI. No references are given to any methods or
sources employed in arriving at costs, and the only number actually
used in the estimation of remedial costs is $500 per acre. Yet,
assurance is given, on p.18 of the Summary Report, that "It can be
concluded that the costs of implementing the guidance at the reference
level would be reasonable and achievable". No justification is
provided for this critical conclusion.
28
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The $500 per acre figure employed for estimating "costs of
remedial actions at various sites of existing plutonium contamination"
appears to include $250 for radiological surveillance, $200 for dust
stabilization and $20 for revegetation, rounded to $500/acre. These
are unreasonable estimates for even the most minimal required action.
They ignore the recommendations of Annex V on implementation, since
estimates of contamination are based on existing data, obtained in a
manner very different from that recommended by EPA, with few, if any,
particle size analyses, and certainly no demonstration that the
statistical probability of being in error is no more than 5-10%.
These estimates, as applied to sites of existing plutonium
contamination, are grossly misleading in terms of costs already
. incurred at these sites.
Of greater concern than these sites of existing plutonium
contamination, are the costs that might be associated with future
incidents of contamination. The possibility of such incidents should
have been recognized and the costs estimated, including not only the
monetary costs of actual cleanup and restoration, but the possibly
greater costs of population evacuation or monitoring, of environmental
impact assessment, of decontaminating homes, roads, or commercial
areas, of income loss from cessation of agricultural or commercial
activities, of demonstrating eventual compliance with the
Guidance—and also including the environmental and non-monetary
societal costs incurred, not neglecting the health risks of the
cleanup operation. Any such total and realistic consideration of
costs might well have led to a different conclusion concerning their
"reasonableness and achievability"; which might, in turn, have
influenced the choice of Guidance recommendations.
Staff Response - The $500 per acre was not determined from
estimated costs figures. It was intended to demonstrate that even if
costs of remedial action were that low, the costs of proposing a dose
limit that established a soil limit below 0.2 uCi/m2 would be
prohibitive.
An estimated cost of remedial action of $500 per acre is
undoubtedly low. However, it is a misconception to consider the cost
of acquiring data on the concentration of transuranium elements in the
soil to be a cost of remedial action. These costs would be incurred
in any case, no matter the guide level established and would,
presumably, be incurred even if there were no guide. The costs of
acquiring data to determine if remedial action is required is better
considered to be a cost of the incident of contamination than a cost
of clean-up and restoration.
An important consideration in estimating the costs of future
incidents of contamination is the probability of their occurance.
This has been ignored by DOE. Actually, a set of probabilities is
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needed for covering a number of situations, so that the expected value
(expected costs) of failure incidents can be determined. The set of
probabilities should include not only the probability of the occurance
of incidences of contamination, but also probabilistic expressions of
the sizes of the expected incidences and the types of lands impacted
(e.g., agricultural lands, forests, urban or industrialized areas.)
DOE's discussion seems to assume that the probability of a future
incident is one for the cases where costs are analyzed and zero for
the cases where costs are not analyzed.
10. Department of Defense
The summary report states that "...generic guidance applicable
to all sites cannot be provided by formal cost-benefit procedures".
It also states that "The primary criteria used in determing the
guidance...(is) that implementation of the guidance be feasible in
terms of overall economic impact". The substance of the guidance is
generic, regardless of what clean-up level is eventually determined
because the guidance is stated in terms of a limiting dose which is
the same for any site. This example is used to illustrate the
inconsistency and ambiguity within the document as well as to question
what was the basis for providing the generic guidance when one hand is
saying economics prevented it and the other hand is saying economics
was the primary criteria.
Staff Response - The objective of the recommendations is to
establish a generic guide which is adequately protective of the public
health. Formal benefit-cost procedures were not used in the
derivation of the guidance recommendations because they do not lead to
a generic guide; they would require that an independently determined
level be established for each site.
Economic analyses were limited to a determination that costs of
implementation for both existing and possible future sites are
reasonable.
11. Nuclear Regulatory Commission
It appears that the costs of taking remedial action for
facilities licensed by this Agency would substantially exceed the
lower limit value of $500 per acre assumed for the proposed guidance.
For example, disposal of surface soils by burial in commercial
low-level waste burial sites would probably equal or exceed the costs
of the general per cubic foot charge for burial. Using a value of $3
per cubic foot (NUREG-0217), would result in an estimated cost of
$5000 per acre for burial charges alone. Using a value of $3 per
cubic foot (NUREG-0217), would result in an estimated cost of $5000
per acre for burial charges alone.
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7
Staff Response - We agree. While costs of remedial action
may vary greatly, depending on level of contamination, location, land
use and ecological factors, etc., the costs of remedial actions can
generally be expected to be greater than $500 per acre. This is
especially true in cases where long-term storage or burial is
required. The assumed least cost value was used solely for purposes
of setting a lower limit on the numerical limits, and does not
represent an analysis of costs for cleanup.and restoration at existing
or possible future sites of environmental transuranium element
contamination.
.31
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2.4 Imp1ementa ti on
1. Colorado Department of Health
The guidance document contains air concentrations and surface
soil levels which are related to the numerical dose rate guidance.
These air and soil values should be inserted in the text of the actual
guidance with qualifying statements as to their appropriate use in the
implementation of the guidance.
Staff Response - The guidance is stated in terms of dose rate
limits to specific body organs. Derived air or soil "screening
levels" are intended to assist in implementing the guidance in a
cost-effective manner, and do not constitute the guidance. It would
therefore be inappropriate and misleading to include, these in the text
of the guidance.
2. Department of Energy
Derived Limits for Air and Soil: The restrictive nature of the
basic radiation dose limits is, of course, reflected in the derived
limits for air and soil. Their derivation also introduces additional
conservatism, which can be only partly justified in terms of their
intended use as screening levels below which no action need be taken.
The derived soil limit is featured in the Summary Report as a
"screening level" and its utility in facilitating economical
implementation of the Guidance is appropriately emphasized (p. 29).
The derived air limit, however, is not found until Annex V (p. 6), and
its use is recommended only as a last resort when other approaches are
"difficult or impossible." It is not clear why the derived air limit
cannot provide a screening level that is more useful than the derived
soil limit, since the air limit is more directly related to inhalation
hazard than is the soil limit. While it can be argued that an air
screening level would ignore the ingestion route, the same argument
applies to the soil screening level as it is presently derived.
Air Screening Level; It is recommended that an air screening
level be identified as such, and given greater prominence in the
Guidance. The level of 1 fCi/m3 defined in Annex V, based on an
unrealistic value of 2.6 fCi/m-*, employed in the derivation of the
soil screening level (Annex 11, p. 33) seems more appropriate. In
order to account for uncertainties introduced by not considering the
ingestion route, and non-ambient inhalation routes, it is suggested
that an "unqualified air screening factor" might be established based
on a detailed analysis of the probability of significant contribution
from other-than-routine inhalation exposure. Any number derived for
an air screening level should, of course, be increased proportionate
to any increase in the basic radiation dose limits.
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Soil Screening Level; The relationship between the quantity of a
radionuclide inhaled, and the quantity of that radionuclide in the
soil is a complex one, which can be predicted only with great
uncertainty. Because of this uncertainty, parameters chosen to
develop such a relationship tend to produce a conservatively biased
result. The mass loading approach employed in this Guidance has many
faults which are pointed out in the Page-by-Page Commentary, together
with suggestions for improvement. However, it is not clear that a
totally different approach would yield a better result.
In these circumstances, a decision as to how conservative is
conservative enough becomes rather arbitrary. However, the following
list of conservatisms presently included would strongly suggest that
the derivation of the soil screening level is more conservative than
it need be:
(a) The assumed mass loading of 100 ug/m^ is 2 to 10 times
higher than shown by .the data of Fig. A 2-2.
(b) The assumed percentage of the airborne particles in the
respirable size range, 100%, is 3 to 4 times greater than shown by the
data of Fig. A 2-3. Such an assumption is especially inappropriate
when used in conjunction with a mass loading of 100 u'g/nr'.
• ; ' - O , • - "
(c) The allowed air concentration of 2.6 fCi/m-5, based on AMAD
of 1.0, is a factor of 2 smaller than would be allowed if the AMAD of
the respirable fraction were more realistically .assumed to be in the
2-5 um range .
(d) The lack of any correction for area size introduces a very
large factor of conservatism, unless extremely large areas are
involved. As pointed out in Annex II (p. 29), this may be a factor of
100 or more for areas with dimensions Fof the order of 50 meters. Such
small areas of contamination are likely to be typical of most future
contamination incidents.
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present soil screening level is probably sufficient to accommodate
such an ingestion component, but it would be more convincing to
estimate the ingestion component independently and add it to an
appropriately reduced inhalation component.
Staff Response - The agency staff does not recommend use of the
soil screening level when inhalation is the principal pathway.
Correlation of soil concentrations with inhalation doses requires
calculational models which necessarily introduce some uncertainties.
The potential inhalation hazard can be more directly related to the
ambient air concentration.
Where ingestion is a possible pathway, the soil screening level
has greater applicability. Although not derived on the basis of
ingestion, the staff has found use of the soil screening level to be
sufficiently concervative to limit exposures to less than the Guidance
dose limits when plutonium is the major constituent of the
transuranium element contamination. The derivation of the soil
screening level was not based upon the ingestion pathway, since that
is extremely site dependent - even more so than the inhalation
pathway. Ingestion is not the principal contributor to the total risk
at sites of existing contamination. For future accidents, the
relative importance of the ingestion pathway is not possible to
predict.
The staff does not agree with DOE that the soil screening level
is more conservative than it need be for the following reasons:
a) A value of 100 ug/m3 was chosen in order to cover the
possibility that localized resuspension could also contribute to the
inhalation dose. These local disturbances would not be reflected in
the average mass loading for the general area. The value of
100 ug/nr5 is consistent with values used by others who also
attempted to factor local resuspension into their calculations (see
Annex II).
b) The percentage of airborne particles assumed respirable is
not 100Z. The assumption was that the particle sizes of suspended
dust are distributed lognormally with an AMAD of 1.0 urn.
c) A factor of 2 is not significant.
d) The size of the area contaminated by future accidents can
not be predicted.
e) This would be a small correction.
f) Justification for the use of the enrichment factor is contained in
Section 3.2, response to comment 30
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3. National Council on Radiation Protection an?! Measurements
The approach taken is to provide dose limits for lung and bone. •
These limits are then to be applied by the agency responsible by a
combination of measurements ;and models involving intake and retention
since the dose to these organs cannot be measured directly.
Unfortunately, these models and coefficients are not well developed
and methods of measurement for inhalation of other than ambient air
are not really available. This will result in adding considerable
conservatism to the analysis and in continuing the controversy over
the safety of a given area.
We" would recommend that the EPA reconsider this approach in favor
of setting soil levels that incorporate all known pathways of exposure
and considering the necessary conservatism in these models along with
any conservatism incorporated in the risk estimates and dose
calculations. While this may provide a limit for some areas lower
than is needed, it will allow consideration of all factors of
conservatism and will provide an unequivocal number that can be
accepted by all. We would also suggest that analyses of different
areas be made taking into account, even.crudely, all possible pathways
to see if the area difference is as great as assumed.
Staff Response - The guidance is stated in the most direct units
possible and is intended to provide for the deviations appropriate to
specific sites. Use of a single "spil sceening level" would remove
the possible options available without any compensating benefit. The
inclusion of all appropriate factors of conservatism in a single
numerical value would necessarily require that the most restrictive
level be applied to all sites, with the consequence of possibly
greatly increased costs of implementation and unnecessary damage to
the environment.
4. National Council on Radiation Protection and Measurements
One of the concerns is the potential impact of future accidents
that may release transuranics into the environment. The current
guidance is not clear as to what should be done. In discussing the
accident, it is stated.that the material should be cleaned up"...as
soon as possible..." However, elsewhere in the document, we find
requirements for detailed assessments are needed for the accident
situation. We also note that no studies of potential accidents and
cost of cleanup at this level as opposed to levels somewhat .higher or.
somewhat lower were done to determine whether the reduction in risk is
worthwhile. While such costs should be included in the .cost of the
operation, there is no reason to believe that this justifies
unnecessary costs if not warranted by the risk reduction.
35
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We recommend that the actions following a future possible
accident be better defined and that a study be made to show that these
limits are appropriate.
Staff Response - It is not possible to predict with any degree of
confidence either the probability or consequence of future incidents
which could release transuranium elements to the environment. The
agency staff believes that the proposed criteria for protection of the
public health are as appropriate for the case of future accidents as
for existing contamination, and that no valid reason exists for
establishing different dose or risk levels. Therefore, the
recommendations of the guidance are intended to be viewed as minimum
performance objectives, and lower values are to be attained when these
can be achieved with reasonable expenditure of resources. Because the
number of possible accident scenarios is virtually infinite, no useful
purpose would appear to be served by evaluating the costs of risk
reduction. The range of remedial actions required will depend on the
magnitude of the accident and on the potential impact on individuals
and populations. In most cases, a rapid response can be expected to
minimize the consequences and reduce the overall costs. The
interaction of all these variables would determine the appropriate
response in each case.
In the opinion of the agency staff, actions following a possible
future accident are generally defined by emergency response criteria
and do not properly fall within the scope of this guidance. Planning
for such emergency response is the responsibility of the agency under
whose auspices the pertinent activity is carried out. If the
anticipated consequences of any ongoing or projected activity are
likely to exceed the guidance recommendations, an EIS may be required.
5. Department of Defense
There is confusion possible in terms of the radionuclides to
which the guidance applies because of the wording. It appears the
guidance covers all transuranium elements, yet it is stated in terms
of alpha radiation doses. Some transuranium elements are not alpha
emitters—how are these to be addressed?
Staff Response - The guidance is intended to apply to all
transuranium elements. Beta emitters (such as plutonium-241)
contribute little effective dose and need not be considered. Daughter
products, which generally are alpha emitters, are included in the
calculations.
6. Commonwealth Edison Company
Commonwealth Edison Company endorses the concept of "screening
levels" for environmental contamination below which costly
36
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environmental surveys need not be undertaken to demonstrate compliance
with the proposed dose rates.o However, we.believe that the derived
value for airborne contamination suggested by the EPA is too low to be
practical, and consequently will not accomplish the purpose for which
it is intended. Specifically, we know of no way to measure accurately
EPA's derived limit of 1 fCi/m3. Further, it will not be possible
to separate out ,the contamination resulting from an unplanned release
of transuranics from ambient background contamination unless
environmental surveys are conducted on a routine basis.
Staff Response - The detection of contaminants in air is a
function of the concentration, sampler flow-rate, sampling duration,
chemical yield of the analytical procedure, and the sensitivity of the
analytical technique (see Bernhardt, Evaluation of Sample Collection
and Analysis Techniques for Environmental Plutonium, in "Selected
Topics: Transuranium Elements in the General Environment", EPA
Technical Note ORP/CSD-78-1 (1978)).
The minimum sensitivity for plutonium-239/240 for most
laboratories is generally around 10 to 20 fCi on the final sample
submitted for nuclear counting. Assuming a fairly low yield of 50
percent this gives a minimum detectable sample activity of 20 to 40
fCi. For this example, this level is raised to 100 fCi per sample, to
insure a reasonable analysis. Using the screening guide of 1 fCi/m-3
and a median sampler flow-rate of about 0.28 nr/minute
(10 ft3/min), 100 fCi is collected in 360 minutes, or about six
hours. For a long-term average, such as is specified by the EPA
Guidance, sampling times of several days to a week are used. Sampling
for about 3 days, using the above parameters, will result in about
1000 fCi (1 pCi) of activity on the filter (based on 1 fGi/m3),
which is well within the ideal range for low-level plutonium 239/240
analysis. An air concentration level for plutonium of 1 fCi/mJ is
greater than current levels of plutonium is ground level air due to
fallout and, therefore, can be detected in the presence of fallout
plutonium.
7. Jefferson County Department of Health
The offsite contaminated area around the Rocky Flats plant is
under my jurisdiction as public health officer for Jefferson County,
and I emphatically disagree with the statement in the guidance that
"all offsite areas probably would be in compliance with the guidance
recommendations". My own survey has shown levels of plutonium in
surface respirable dust to be as high as 3,390 times fallout levels.
Although the guidance states "The area is sparsely inhabited, and
there are few people living in the particular area of concern", please
be advised that the State Health Department approved this land (with
3,390 times fallout levels of plutonium) for residental development,
and this move was blocked only with considerable difficulty. I
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estimate that in the area of concern originally established by the
State Health Department, that as many as 100,000 persons may be
settled if the efforts of developers are not restrained. Much of this
area is now under development.
Table 2.1 on page nineteen compares the cost of remedial actions
with existing plutonium contamination as indicated by isopleth maps.
The areas noted to require remedial action at Rocky Flats are too
small,^in view of a recent survey utilizing respirable dust samples.
There is significant contamination outside the isopleths referred to
in this table.
Staff Response - The Agency staff does not believe that guidance
recommendations should be evaluated in terms of multiples of fallout
levels, but rather in terms of risk to the health of people. The
staff also disagrees with the analytical procedures proposed by
Dr. Johnson for surveying plutonium levels in the environment. The
areas of disagreement are discussed in Section 7 of this document.
The concentration of plutonium in offsite soil is highest near the
site boundary and decreases with distance from the site. Therefore
there is a potential for only a limited number of persons to be
exposed to levels approaching guidance recommendations when the areas
surrounding Rocky Flats are developed. The vast majority would
potentially be exposed to much lower levels. The agency staff
believes public health protection will be achieved under these
conditions.
8. Ilene Younghein
Annex 1 p. 12 "The milk surveillance network around NTS does not
analyze samples for plutonium." Why not? p.17 "of the approximately
8 curies onsite, more than half is believed to be stabilized by
coverage with an asphalt pad and remedial measures are being taken to
control the remainder to the extent practicable." Is asphalt
considered to be a permanent solution to plutonium contamination? You
did not define your remedial measures nor what is meant by extent
practicable. What is really being said-that the measures taken are
temporary-that to really remove the contamination would be extremely
expensive and probably impossible.
Staff Response - (a) Plutonium does not accumulate in milk and
cannot be detected (b) The Agency has not provided a judgment on the
adequacy of remedial actions. The statement is a report on an
existing situation.
9- N.Y. Federation for Safe Energy
The guidance speaks of clean up. How does one clean up water,
and where does one take soil that needs scraping?
38
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Staff Response - Transuranium elements are generally very
insoluble in water and are associated primarily with sediments.
Restrictions on use of drinking water supplies may need to be imposed
if dose rates to individuals at a specific location approach the
guidance recommendations.
Contaminated soils may be stored in designated repositories. A
number of commercial-facilities have been licenced by the States and
the Federal government operates several high-level waste storage
repositories.
10- Colorado Environmental Health Association
If the proposed guidance of 0.2 uCi/m^ is affirmed by EPA and
the scientific community, we recommend that all land areas with soil
contamination exceeding the guideline be mitigated as described under
"Remedial Actions and Economic Evaluation". Applying the 0.2 uCi/m^
guideline to the attached figure of soil contamination would require
that any area exceeding 30 dpm/g would require mitigation.
Approximately 1 square mile outside the Rocky Flats boundary and about
1.5 square miles inside the boundary exceed the guideline.
Staff Response - The guidance recommendations are in terms of
dose rate limits to individuals in a critical segment of the
population, and not in terms of a soil contamination level. The scope
of remedial actions which may be required to achieve compliance must
be determined on a site-specific basis. The guidance is applicable
only to those areas outside the limits of Federal facilities.
11. Colorado Environmental Health Association
Although the guideline fails to recommend a specific sampling
technique, it appears that the respirable dust technique .offers the
most practical method of estimating exposures to human populations
since dust-borne plutonium may be inhaled and is thought to cause lung
carcinomas and leukemia.
Staff Response - We do not agree. Soil sampling and analysis.
methods represent a secondary means of assessing health impacts and of
implementing the guidance. The superiority of the "respirable dust
technique" has not been demonstrated (see Section 7).
*^• Colorado Environmental Health Association
We feel that the discussion of soil contamination in the
environmental impact statement has not thoroughly addressed the
controversy pertaining to the amount of radioactivity in the soil. If
the scientific community finds the EPA proposed Guidelines for
Transuranium Elements in the Environment to be appropriate, then the
standard should be applied to Rocky Flats and discussed in the Final
EIS.
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Staff Response - The guidance is not intended as an
implementation manual and therefore does not discuss the merits of
different soil sampling and analysis methods. Application to specific
situations is the responsibility of Federal agencies having site
juridiction. Preparation of an Environmental Impact Statement is
required only for major Federal actions.
13. Department of Defense
This sentence is a non sequitur. It does not follow that just
because all sources of transuranium elements are under direct control
of the Federal Government that Federal guides are an adequate means to
limit any problems of environmental contamination by the transuranium
elements.
Staff Response - The Agency believes that Federal Radiation
Guidance is both an adequate and equitable means of providing
protection of the public health by establishing uniform dose rate
limits for exposures due to environmental contamination by
transuranium elements, while maintaining the flexibility of
implementation not generally afforded by standards.
14. Department of Defense
This is typical example of use of non-specific, non-meaningful
words and phrases. The term "as soon as possible" has little stature
in a regulatory or compliance sense. A definite time should be
specified, (p-18)
Staff Response - The Guidance contains recommendations which are
intended to have a certain degree of flexibility. The indeterminate
nature of the type, magnitude, and location of future incidents of
contamination makes it both inappropriate and impossible to give
specific directions for remedial actions. The objective of remedial
actions must be to minimize both the immediate and long-range risk to
exposed persons. It is the responsibility of the agencies charged
with implementation of the Guidance to develop an adequate and timely
response in each instance.
15. Department of Energy
Some recognition should be given to the fact that "as soon as
possible after occurrence" could be a long time because of the
complexities of establishing the extent and location of contamination
and the cost benefit analysis required before remedial measures are
taken—not to mention the possible requirements for an environmental
impact assessment. The idea that there might be a desirable
compromise between immediate, thoughtless recourse to bulldozers, and
a 5-year study of environmental impact, should somewhere find
expression in this Guidance, (p-18, line 25)
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10
Staff Response - It was deemed appropriate to allow flexibility
in implementation procedures and schedules. It is expected that
common sense judgments, designed to minimize the health risks of
individuals and the population, will be made by designated officials.
However, the agency staff wishes to emphasize that analyses
indicates that, when a contaminating event occurs, most of the
radiation dose associated with the event is committed within a short
time (within a few months) unless protective measures are taken. This
is because the resuspension factor for newly deposited material is
much higher before weathering and movement into soil surfaces occurs.
Should a potential contamination event occur, the responsible
Federal agency should take immediate remedial measures to prevent the
airborne movement of the transuranium element. These measures are
likely to be temporary measures that simply hold the transuranium
elements in place. Following such temporary measures, remedial
measures appropriate to a long term solution should be implemented.
16. Department of Defense
For health physics and protection reasons, why not also state the
mi11rad numbers in millirem equivalents. From a regulatory
standpoint, millirad is preferred for regardless of what quality
factor is chosen for alpha, the guidance is the same. But for
practical purposes, the protection industry works in millirem.
(p-21, lines 3-4)
Staff Response - The conversion, if necessary or desirable, can
easily be made in implementation manuals.
17. Department of Defense
A conclusion that is not supportable appears in the following
paragraph where it is stated that "the control measures are expected
to result in levels well below those specified in paragraph one" i.e.,
1 and 3 millirad. Why would this be expected? If remedial action is
done to the degree required .literally, then one would reasonably
expect that the levels would be not more than 1 and 3 millirad, but
certainly not "well below." This typifies many examples of the
luxuries the authors have taken throughout the document in making
subjective statements, loose associations and rambling discussions.
(p-21, para. 1)
Staff Response - In general, it may be expected that, if remedial
actions are applied to all areas which exceed,the soil "screening
level," this will result in an average environmental contamination
level lower than the "screening level" and result in dose rates to
individuals well below the guidance recommendations. It is not
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11
reasonable to expect that responsible implementation of the Guidance
recommendations, where remedial actions are actually required, would
stop at the minimum requirement. Literal interpretation of the
"screening level" as the absolute lower limit is obviously not in the
spirit of achieving maximum radiation protection of the general
population.
18. Department of Defense
Remedial action is stated as "may be.required at any site that
fails to meet these criteria." Presumably, since this is a guidance
that limits the dose to man because of contamination of transuranium,
remedial action would be required at any site that fails to meet the
criteria, (p-30, Sec. 3.4)
Staff Response - Adherence to the guidance recommendations on the
part of the responsible Federal agency is not mandatory, but adequate
justification must be given for deviation.
19. Department of Defense
The DOE does not believe that "all sources of transuranium
elements are under direct control of the Federal Government" (e.g.,
foreign space satellite components). Further it does not follow that
"Federal Guides...are — an adequate means to limit any problems of
environmental contamination," especially since all potential sources
of transuranic elements are not under Federal control, (p-12, lines
9-12).
Staff Response - The amounts of transuranium elements not under
direct control of the Federal Government are considered minimal and
unlikely to cause significant problems. Foreign intrusions, such as
the reentry of a Soviet space satellite, would need to be considered
on an ad hoc basis. Federal intervention is considered likely in the
event of any substantial contaminating event involving transuranium
elements, irregardless of ownership.
20- Department of Energy
Again, unless "guidance recommendations" is understood to be
strictly limited to the radiation dose limits, it is erroneous to say
that they represent a "maximum value." The wording encourages
misunderstanding, since the "screening level" might well be considered
a "guidance recommendation" but should certainly not be considered a
"maximum value." (p-20, lines 15-16)
Staff Response - The comment indicates a misinterpretation of the
statement referred to. The recommendations are to be considered as
upper limit values and the principle of "as low as reasonably
achievable" is to be applied to the extent practicable.
42
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12
21. Department of Energy
This sentence should be referenced to the place in this Guidance
where "representative measurements" and "reasonable procedures and
assumptions" are defined, (p-24, lines 2-5)
Staff Response - The discussion of details pertaining to
implementation procedures is not appropriate in this Guidance.
22. Department of Energy
Although a soil "screening level" is a potentially useful
concept, ambiguities concerning how the screening level is to be
employed, either technically or administratively, make it of
questionable practical value. Annex V offers little help in this
regard, (p-29, lines 11-15)
Staff Response - The soil "screening level" is an optional method
available to the implementing agency, which we believe to be practical
and useful. Development of detailed technical and administrative
procedures are the responsibility of the implementing agency.
23. Department of Energy
"Remedial action may be required." It is nowhere quite clear
whether remedial action is ever required, or whether radiation dose in
excess of EPA Guidance may be justified in some manner.
(p-30, lines 7-8)
Staff Response - The Guidance recommendations should not be
exceeded unless deviations are justified.
24. Department of Energy
The alternative of "restricted access, or use" is mentioned, but
receives no further consideration. There are degrees of usage that
might well be discussed, (p-30, line 12)
Staff Response - The Guidance document is not intended to be an
implementation manual.
25. Jefferson County Department of Health
I am concerned with the criteria on page 60957 in the first
paragraph, Rationale for Guidance. One of two primary critera used in
developing this guidance, "That any actions required by implementation
of the guidance be practical in terms of overall^economic
requirements". In view of the nature of the guidance proposed, I feel
that economic concerns have really been given foremost consideration,
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13
perhaps with intent to minimize any economic impact on federal
agencies or private corporations which have contaminated offsite
lands. It appears to me that the concern for the public health has
been given lower priority here.
Staff Response - The criteria for establishing the guide level
was that the risk to exposed individuals be acceptable. This level
was determined with no consideration for the costs of remedial
action. EPA then determined that the costs of performing the required
remedial actions were practical.
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2.5. Biological and Environmental Models
1. Ilene Younghein
"A more detailed treatment of the dose to children is not likely
to result in appreciable difference in the risk since most of a
person's body burden is accumulated during adult life, not
childhood." This statement is very questionable. Children's cells
grow and divide faster so radiation damaged cells proliferate faster.
Also children carry the damaged cells for longer periods of time.
Children too would be more penalized by the life shortening process of
radiation than an adult. It is also possible for plutonium to cross
the placenta, from the mother's blood into the blood of the fetus,
where it may kill a cell responsible for development of part of an
organ, such as heart, brain, liver etc, causing deformities to occur
in the developing fetus. This mechanism for production of fetal
deformities is called teratogenesis and is different from the
deformities caused by genetic mutation in the egg or sperm (similar to
the drug thalidomide). The discussion on risks to children is
incomplete and misleading (Section 3.2 p.5).
Staff Response - All of the points mentioned in the comment were
considered in the assessment of risk. Refinements in the dose model
for children are unlikely to change the numerical risk estimates to
any appreciable extent.
2. Ilene Younghein
Contrary to your statement, it is possible to get a lifetime dose
of Pu 241 (half-life 14.8 years) and Cm (half-life 17.9 years). These
elements stay radioactive for about 148 and 179 years-longer than the
life of most people, especially those exposed to plutonium.
Staff Response - For a relatively constant food intake quantity
characteristic of most per.sons, the annual dose rate from ingestion of
transuranium elements is expected to be roughly proportional to the
environmental contamination level. For-Tsuch relatively short
half-life radionuclides, the initial dose rates are not expected to be
maintained over the entire lifetime of an individual.
3. Ilene Younghein
"..for chronic iradiation due to Pu-239, 200 bone cancers will be
produced per 10^ rad to a 7 kg skeletal mass. In terms of the dose
to mineral bone, mass 5 kg, utilized in this analysis, there results
yield 140 bone cancers.per rad to osseous tissue." This section is
unclear at besti at worst incomprehensible.
-------
Staff Response - The statement is a simple scaling of a result
obtained from the technical literature to the slightly smaller bone
mass used in the EPA analysis to provide consistency with ICRP models.
4. Commonwealth Edison
Although the proposed guidance seems to apply to all Federally
licensed facilities with any transurariics in their systems, it would
be technically unjustifiable to require nuclear power plants to
conduct environmental surveys following every planned release of
radioactivity to prove that the derived contamination guidance has not
been exceeded. • •-.•••• ' . • .
Staff Response - Federal Radiation Guidance is applicable only
to the Federal agencies and is advisory to'the States. It is prudent,
however, for Federally licenced facilities to evaluate the impact of
unplanned releases that are sufficiently large to cause dose levels to
populations of the same order of magnitude as the guidance <
recommendations.
5. National Council on Radiation Protection and Measurement
The screening level derivation in Annex II does not reflect the
requirements of the remainder of the document. Only the ambient air
concentration is used and even this is calculated by a mass loading
technique with an enrichment factor that has not been justified by an
experimental work. We find, for example, that ingestion for the-
reasonably serious home garderner could be of importance if the
uptakes from the GI tact from Annex III are used. This is
particularly true for the nuclides other than plutonium. '
We recommend a detailed study of all pathways in derivation"''of
the screening level with some emphasis on size of the area. In **
particular, the inclusion of the enrichment factor which apparently
makes a difference on only a factor of 1.5 and has never been
demonstated to be proper should be reconsidered.
Staff Response - The staff has analyzed the situation where the
entire surface inventory of 0.2 uCi/m2 consists of transuranium
nuclides other than plutonium. These nuclides generally have higher
plant uptake and GI tract transfer factors and, therefore, result in
higher doses. However, the dose rates are not projected to exceed the
guidance limits even for the serious home gardener.
A discussion of the applicability of the enrichment factor can be
found in comment 30 of Section 3.2.
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^" Jefferson County Health Department'
It must be noted that although "soil contamination levels can be
related to a corresponding air concentration by use of a resuspension
factor", in the copy of the proposed guidelines it is admitted that
such a resuspension factor may vary by a factor as large as one
million, which makes the use of such factors highly questionable. The
guidance states on page 60958 that a soil contamination level of 0.2
microcuries per square meter (with samples collected at the surface to
a depth of 1 cm. and including particles less than 2 millimeters in
size) would establish a reasonable "screening level". The use of
whole soil samples to evaluate a hazard from respirable dust is
inappropriate and will underestimate the hazard, as I have , .
demonstrated in my work around the Rocky Flats plant in Jefferson
County. In, addition, the value proposed is too high to be acceptable
to the general public, in my opinion, if the public understands the
range of estimates of ill effects that could result in a total
increase in all neoplasms of perhaps 1 to 2% over a .period of 70
years. The incidence of all genetic disease.could increase by 1% and
ill health related to chromosome mutation by about 7% for all
succeeding generations from the. proposed guidance dosage level.
Staff Response - Annex II of the Proposed Guidance document
discusses in detailed the difficulties involved in applying the
resuspension factor concept to predicting the resuspension of surface
soil. Because of the many limitations of the resuspension factor
concept, the agency staff chose not to use it when deriving the soil
screening level. Instead the staff used the average airborne mass
loading when deriving the soil screening level, after some
modification to account for the distubution of/activity with soil
particle size.
It has not been demonstrated that the soil sampling and analysis
techinque proposed by Dr..Johnson correlates in any way with the
airborne4concentrations observed in Jefferson County. In fact, since
this analytical technique drastically alters the distribution of
activity with soil particle size from what it is in the environment\
it is doubtful that any such correlation can be made. The staff has
compiled a detailed critique of the sampling and analysis method .
proposed by Dr. Johnson. ( See Section 8).
Additionally, the staff has identified several erroneous
assumptions made by the commentpr in converting levels of resuspended
dust into dose from inhalation. These errors result in projected
doses far exceeding those which would actually be received by persons
living in the vicinity of land contaminated at the level of the.
0.2 uCi/m2. (See Section 8)
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7. Jefferson County Health Department
In paragraph two on page seven, the report states "the uptake by
plants is relatively small, and most animals, including humans, have a
high discrimination factor against transfer of these elements into the
body tissues". However, some plants, such as algae and seaweed, have
the ability to concentrate plutonium, presumably in a form that can be
assimilated by animals. Chelating agents present in soil over a
period of time may make the plutonium oxide in soil available for
uptake by both plant and animals to a greater extent.
Staff Response - The uptake of plutonium by plants has been the
subject of numerous laboratory and environmental studies. These
studies have demonstrated a low uptake by terrestrial food plants.
The uptake factors are typically in the range of 10"^ to 10"^. It
is true that some marine plants show higher uptake factors, but their
contribution to the American diet is very small.
The Guidance establishes a limit on doses from all pathways to
which persons are exposed and, if a situation arises where the marine
food pathway is significant, this would not invalidate the Guidance.
Likewise increased solubilization which increases the uptake of
plutonium by plants would not invalidate the Guidance.
Several mechanisms have been suggested which can increase the
solubility of plutonium. Much of this research is in the preliminary
stage and a quantitative discussion of the time required for such
transformations is not currently possible. The preliminary data,
however, have not demonstrated that rapid transformation of plutonium
occurs under conditions generally encountered in the environment.
Most likely, if such transformations do occur, they occur over long
periods of time (decades).
8. Jefferson County Health Department
The table on page five (table 1.2) indicates a soil concentration
of 0 to 1,000 picocuries/gram (pCi/g) of plutonium on site. However,
these values have been previously reported to be as great as
13,600,000 pCi/g (INV-10 report)*. Therefore, to say that the onsite
maximum is in excess of 1,000 pCi/g seems misleading. The same
comment may be applied to the level given for plutonium in soil at the
plant site boundary. As much as 80 pCi/g has been measured in samples
of surface respirable dust off site.
* "Levels of 2 x 105 dpm/g to over 3 x 107 dpm/g reported."
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Staff Response — All uncontained on-site soil at the Rocky Flats
Plant site contaminated above 2000 pdi/g (about 21,000 square feet) is
currently being removed by DOE.
9. Jefferson County Health Department
In addition to resuspension of plutonium from surface dust, we ,
must also consider the release of particulate plutonium from
plutonium-processing plants. These particles are for the post part
less than five microns (micrometers) in size and large numbers are -
released at times. Eight days after a fire at Rocky Flats in 1957, as
many as 125 million of such five micron particles or .their equivalent
were released in a single day from one stack. A two micron particle
of plutonium oxide, if inhaled, would produce a dosage of over two
millirem to bone. A particle five microns in size could be inhaled
and retained and produce a dose about 40 millirem to the lungj 1,700
millirem to the tracheobronchial lymph nodes, over 130 millirem to the
bone, 50 millirem to the liver, eight millirem to the kidney, and two
millirem to the gonads, where a pattern of microdeposition of
plutonium would give a proportionately greater effect than the same
order of size as bacteria, and may be blown by the wind for great
distances. A single particle only two microns in size, if;inhaled and
retained, will produce a dosage exceeding the EPA 4 millirem annual
dose.
Staff. Response - These recommendations are to be used only for
guidance on possible remedial actions for the instances of existing
contamination or of possible future unplanned releases similar to the
incident described. .
The agency staff does not agree with these dose calculatins. As ,
indicated earlier, the agency staff has identified several erroneous
assumption made by the commentor in converting from levels of
resuspensed dust to inhalation doses. These are described in
Section 8 of this document.
10. Jefferson County Health Department
On page 28 (implementation) the guidance states t"in most cases
the critical pathway for exposure to transuranium elements is through
inhalation of airborne particulates derived from resuspension of soil ,
particles and compliance with this dose guidance can be demonstrated
by measurements of air and/or soil concentration". The problem with
the use of soil samples (agricultural soil) is that much of this
material is coarse and is not windblown, and when included in the
samples used to evaluate windblown material, misleadingly low results
are obtained. The best way to evaluate a hazard from airborne
contaminated dust is by use of a respirable dust sample from the
surface of the soil.
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Staff Response - Regardless of the soil sampling technique, a
relationship must be established between the measured soil
contamination and the actual airborne activity. Dr. Johnson has not
established such a relationship for his respirable dust sampling
technique. Even if a satisfactory correlation could be established
for the sampling method, the Dr. Johnson's techniques does not
correspond with the lung deposition models developed to calculate
inhalation doses. These models require a value for the total airborne
activity and a description of the, distribution of that activity as a
function of particle size. Dr. Johnson's technique does not provide
such data and therefore does not provide a method for evaluating the
potential inhalation hazard. ,, , , • , . , .
11. Jefferson County Health Department
There are problems with the estimation of the air concentration
of plutonium due to the efficiency of filters used in air monitoring
devices, the velocity of air intake, the variation in concentration of
resuspended plutonium by height above the ground surface, and other
local factors. In addition, such measurements are given in averages
per cubic meter whereas plutonium is particulate, i.e., the inhalation.
of one particle of respirable size (two microns) per year would exceed
the 1976 EPA regulations. The effectiveness of such filters in s
retaining the orders of sizes of plutonium oxide smaller than 0.1
micron needs to be evaluated. I would agree with the guideline that
"therefore soil measurements may be more advantageous in certain
areas" except that these should always be performed. l
Staff Response - There are problems with any method of measuring
environmental contamination level, whether it be in air, soil, or.
water. Such measurements are difficult because of the generally low
concentration levels, non-uniform distribution, and other similar
factors. The collection efficiency of filters and of other sampling
devices can generally be determined and appropriate correction made in
the reported results.
The agency staff prefers the measurements of airborne •-.
radioactivity to soil measurements when evaluating an inhalation.
hazard, for the following reasons:
1. Air measurements provide a method for averaging over
larger volumes than do soil measurements.
2. Air measurements show less point-to-point variation. ,
Values of soil concentrations can vary dramatically over a
distance of only a few meters. How this variation will be
reflected in the overall inhalation risk is difficult to
evaluate.
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3. Air monitoring can be performed on a continuous basis and
therefore provides a method for averaging over many changes
in climatic factors.
4. Air measurements provide a method for evaluating the
impact of a contaminated area which is some distance from the
population at risk.
• ' " . ' .• . \ - - '. • "I . ' '', .
5. Measurements of the radioactivity in the air to which
populations are exposed can be more directly correlated with
the potential inhalation hazard. Soil measurements require a
calculational model to relate the soil levels to the '
resuspended activity. Such models introduce uncertainties
and, therefore, must be conservative in nature so that the
actual inhalation hazard is not underestimated.
12. Jefferson County Health Department
The soil sampling suggested by the agency is agricultural soil,
ie., ..partible sizes under two millimeters in size, collected to a
depth of one centimeter. This type of sample is inappropriate for use
in evaluating a hazard presented by-contaminated respirable dust. The
suggested "screening level" for soil contamination' of 0.2 microcuries
per square meter is equivalent to about 29 disintegrations per minute
per gram, assuming a soil density of 1.5 gram per cubic centimter, and
is a concentration much too high to be considered safe for residents
of such areas. This level is about 15 times greater than that now '
recommended by the Colorado State Health Department (0.01 microcuries
per square meter^ or 2 dpm/g) except that the state interim standard
is addressed only to plutonium, and does not include other
transuranium elements. Samples of respirable dust compared to whole
soil samples collected by the method used by the state have indicated
as much as 285 times as much contamination with plutonium as indicated
by whole soil samples. Plutonium in the surface respirable dust
offsite is as much as 3,390 times the background value from fallout in
Colorado. Therefore, I believe that the use of whole soil sampling,
as advocated by these proposed guidelines, is inappropriate and will
certainly underestimate the hazard.
Staff Response - The Guidance recommendations refer only to dose
rates to organs of persons in the general population. Comparisons on
any other basis are inappropriate. .
A critique of the respirable dust sampling method proposed by Dr.
Johnson is contained in Section 8 of this document.
51
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oersistence is not a requirement
*38Pu daughter of 242Cm is not
2.6 Miscellaneous Comments
1. Department of Energy
Footnote is misleading. Long
for environment impact. Also, the
shortlived, (p-2, Table 1.1)
Staff Response - We agree.
2. Department of Defense
"more or less uniformly" is an ambiguous and misleading
description of the extensively studied distribution of fallout.
(p-3, lines 8-10)
Staff Response - The wording is meant to convey the idea that,
while local concentrations may vary from the mean by up to a factor of
two, fallout represents a relatively constant fraction of the total
background level in the United States.
3. Department of Defense s
"More or less uniformly" is ambiguous and misleading with regard
to fallout. Why not just state that fallout has been slowly deposited
over the lands and oceans and the level now is x microcuries/meter2?
(p-3 lines 8-10)
Staff Response - Fallout has not been deposited entirely
uniformly and varies by more than a factor of four from the lowest to
the highest current soil concentration level. Designation of an
"average" background level of "x" microcuries/meter^ would be
erroneous and misleading.
4. Department of Energy
"The principal modes of transport" are not as certainly
established as this sentence would suggest. (p-4, lines 13-16)
Staff Response - The agency staff has considered information
applicable to all modes of transport to man to the extent available in
the literature, and believes this to be sufficient to support the
Guidance recommendations.
52
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5. Department of Energy
Title of table might more appropriately refer to transuranics
rather than plutonium, since 20,000 Ci of U.S. fallout must include
241Am. If only plutonium, the U.S. fallout inventory is 16,000 Ci.
(p-5, Table 1.2)
Staff Response - We agree.
6. Department of Energy
Several inventories and concentrations noted as "greater than"
have little meaning. How much greater than? The comparison between
45 Ci listed for the Trinity Site and 155 Ci listed for the Nevada
Test Site suggests that " 155" must mean "very much greater than,"
since it seems that the single small test at the Trinity Site would
produce insignificant fallout compared to the many tests at the Nevada
Test Site. This njay not be true but the reader may well draw such a
conclusion, (p-5, Tabel 1.2)
Staff Response - The data were derived from various sources and
indicate best estimates of the Department of Energy.
7. Department of Energy
Listed soil concentrations have no va|ue without specification of
sampling depth. The footnote seems to imply a 1 cm depth, but this is
probably not applicable to all values. It would aid comprehension if
all soil levels throughout the document were converted to an area
basis rather than leaving it for the reader to make such a conversion,
which he often cannqt make because of lack of information on sampling
depth and soil density. (p-5, Table 1.2)
Staff Response - Conversion of measurement results is only
possible where all the data are available. Sampling depth, variation
oftconcentration with depth, soil density, and other variables are
often not explicitly stated and would make the results of conversions
aft|biguous. Additional details for specific sites are given in Annex I.
8. Department of Energy
There are numerous inconsistencies between Table 1.2 and Table A
1-5 of Annex 1. These two tables should either be identical, or one
should be abstracted from the other, (p-5, Table 1.2)
Staff Response - We agree.
53
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9. Department of Energy
There is a major problem with Savannah River Plant data, which
cannot be verified in references cited in Annex I. The total
inventory should be 1-2 Ci. "N area" should be "H area." The correct
numbers are: for H area, 0.41 pCi/g; for F area, 0.08 pCi/g; and for
perimeter, 0.01 pCi/g.
These numbers are derived from data presented in McClearen, H. A.,
"Plutonium in Soil at the Savannah River Plant," DPSPU 74-30-14, AEC
Environmental Protection Conference, Albuquerque, NM (1974). (p-5
Table 1.2) ...**»
Staff Response - We accept the Department of Energy correction.
10. Department of Defense = «
1
What is the significance of light lines vs heavy lines in the^ "
schematic? (p-6, Fig. 1)
Staff Response - Heavy lines are intended to represent the more
significant pathways.
11. Department of Energy
Caption should explain significance of different kinds of lines.
Arrowhead is omitted on line from water to sediments, (p-6, fig. 1)
Staff Response - We agree. (see DOD comment 10)
12. Department of Energy
^^Am is probably more important than 238pu> (p-7, line ,23)
Staff Response - Am-241 is only more important in weapons grade
materials.
13. Department of Defense
The inference concerning biology is loose. It is not established
that the pulmonary region is not a probable site for plu.tonium induced
cancers nor is it true that plutonium oxides may contribute only
marginally to bone cancer, (p-9, para 1 and 2)
Staff Response - The information given here is specified as
applicable only to the inhalation pathway. Details on the assumptions
used in dose calculations are given in Annex III.
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14. Department of Energy
The pulmonary region may well be the most probable site for
plutonium-induced cancer in humans. (p-9, lines 4-6)
Staff Response - The statement in the document merely says that
the Agency combined the two more conservative assumptions.
15.,. Department of Energy , , ,. ••• ••..-• -:<'"*•'
Some forms of plutonium oxide, particularly 238Pu02, may be
rather quickly translocated to bone. In such cases the frequency of
bone tumors may exceed that of lung tumors. (p-9, lines 11-14)
Staff Response - True. The more isoluble forms of plutonium oxide
do translocate quickly and increase the risk of bone and liver
cancers. However, in that case, the risk of lung cancer is decreased
because of the shorter residence time in that organ., (See Section :6)
16. Department of Energy , ,
"dpm/g in the top 1/8 inch of soil" should be translated into
units used elsewhere in the document. (p-11, line 17)
Staff Response - The units are stated,as given in the applicable
Colorado standard. . ..,,,.
17. Department of Energy
Here and elsewhere in the Summary Report, it would be very
helpful if more specific references were made to material in the
Annexes,that support the conclusions stated. The lack of supporting
justification in this Section is acceptable only if one is explicitly
directed where this justification can be found, (p-14, Sec. 2.4)
Staff Response - In the absence of more detailed and definite
information, an answer cannot be provided for this comment.
18. Department of Energy . . „ ,,
'"• This sentence is grammatically^confusing and difficult "to follow.
(p-14, lines 17-21) ! "\" " t ' •
StaffResponse - We believe the intent to be clear. r , |
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19. Department of Energy
The first criterion, by use of the words "very small," almost
seems to preempt the second criterion. What happens if implementation
at a "very small" risk level is not feasible? The occurrence of such
ambiguities here and elsewhere tends to reduce the effectiveness of
the document. (p-14, lines 21-25)
Staff Response - The ambiguities referred to may be in the eye of
the beholder. The agency staff believes that DOE estimates of costs
are greatly excessive and that a very small risk level and achievable
costs of implementation are compatible in most cases.
20. Department of Defense
To what does "change by factors of 10" refer? Is it costs, soil
concentrations, calculational precision? This is unclear.
(p-10, line 10)
Staff Response - "changes of factors of 10" is intended to apply
to soil concentration.
21- Department of Energy
The intended meaning of "beyond the boundaries of the source from
where it orignated" is not clear. Does this mean off-site?
(p-18, line 2-3)
Staff Response - Yes.
22. Department of Energy
The term "numerical guide" is ambiguous. What exactly is meant?
(p-18, line 23)
Staff Response - The term refers to the numerical guidance
recommendations.
23. Department of Defense
In view of later comments on Annex VI, this table adds nothing
for the summary, (p-19, Table 2.1)
Staff Response - The table is intended to give a comparison of
impacts at alternative guidance recommendation levels and may be
useful from that viewpoint.
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24. Department of Energy -
The term "numerical guide" is ambiguous. If, for example,, it
were interpreted to mean "screening level," the statement would be
incorrect. (p-20, line 1)
Staff Response - See response to comment 22.
25. Department of Energy • ;'•
The appearance of the official "Text of Proposed Guidance" at the
end of the section that discusses it, is awkward. It would be easier -
to understand the discussion if the Guidance appeared at the beginning
of this section and was followed by discussion which went somewhat
farther in justifying the exact form of the Guidance, (p-20, line 19)
Staff Response - Section 2 of the Summary document discusses the
rationale for the proposed Guidance. The text follows logically.
26. Department of Defense ,
This chapter supposedly has the purpose of summarizing the
proposed guidance, yet the proposed guidance does not appear until
page 20. As a matter of writing style and to improve clarity, why not
introduce the chapter with a statement that EPA, under its appropriate
authority, is proposing guidance for transuranium elements, etc., the
text of the proposed guidance is etc., and then follow with the
discussion. It is now presented awkwardly if not backwards.
(p-20, Section 2.5)
Staff Response - See response to comment 29.
27. Department of Energy
It does not appear that the Guidance, as stated here, would
permit exceeding the dose limits on the basis of risk-benefit
considerations. This seems unfortunate. For example, the very low
risk incurred by exceeding the specified limits by some small factor
might well be acceptable if the alternatives to cleanup lead to an
uhacceptable risk-benefit ratio, (p-21, lines 3-4)
Staff Response - Guidance recommendations retain flexibility of
implementation.Deviations may be permitted when properly justified.
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28. Department of Energy
• I • III ..II •Illl ••••.« I •! I .!•! . | „ . | .I.., , , f, ,
"Guidance on possible remedial action" sounds very weak What
exactly does it mean? It should be explicitly defined in the text of
the Guidance. (p-21, lines 11-12)
Staff Response - We agree. The text has been changed.
29. Department of Energy
Definition of "critical segment of the exposed population" is
Staff Response - The guidance limits apply to that group of
persons in the general environment who, because of residency or other
factors can on the average be expected to receive' the highest lifetime
radiation dose from a specified source of transuranium elements,
30. Department of Defense
Definition a. "Critical segment of the exposed population" is
vague, Definition d replace following with during. Definition g.
general environment" means all the environments outside the
boundaries of Federally licensed or controlled facilities, does this
mean that lands inside the boundaries of similarly controlled
facilities are exempt from the guidance? Definition h. Why define
curie when it has not been mentioned or employed previously. One
is
Staff Response - a. "Critical segment of the exposed population"
defined above; b. we agree; c. yes. The guidance is applicable
only to those persons residing outside the boundaries of Federally
licenced or controlled facilities; d. see response to comment 32.
31. Department of Energy
"Equilibrium dose rate following chronic inhalation" is
incorrect. It should be changed to read, "equilibrium dose rate
during chronic inhalation." (p-22, lines 3-4)
Staff Response - We agree.
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32. Department of Energy
Since."curie" is not employed anywhere in the Text of Proposed
Guidance, why is it defined here? If mCi and fCi are to be defined,
why not uCi, nCi and pCi? (p-22, lines 17-21)
Staff Response - The definition should be deleted. '; ; .
33. Department of Energy ...,:.;
The "small fraction" translocated is not small, (p-25, line 6)
Staff Response - The solubility of most inhaled transuranium
nuclides is small and therefore the fraction dissolved in the
bloodstream is necessarily small.
34.. . Department of Energy . : - *. •; .- >.. ••„ *.-. '•'-. ,; ' ' r
This sentence should be referenced to the place in this Guidance
where bone and liver cancer risk is derived, (p-25, lines 18-22) ,
Staff Response - The section is a summary of the detailed
evaluations in Annex 3.
35. Department of Energy •-..-•
The term "cohort" should be defined. (p-25, footnote)
Staff Response - The definition of "cohort" as used dn the
Guidance is": a group of 100,000 individuals with age in common. In:
the analysis, the mortality experiences of all the members of the
cohort are traced from birth to death.
36. Department of Energy
This sentence should be referenced to the place in this Guidance
where genetic risk is derived. (p-26, lines 16-17)
Staff Response - Genetic risks is discussed in detail in Annex 3.
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37. Department of Energy
The genetic risk to succeeding generations is confusingly and
inaccurately stated. The numbers quoted are an equilibrium rate
assuming continuing exposure, generation after generation. The term
as high as is confusing, when followed by a range.
(p-26, lines 19-22)
Staff Response - We agree, see Annex 3.
38. Department of Defense
Replace and with either £s or since. (p-27, line 3)
Staff Response - The sentence reads as intended.
39. Department of Energy
The term "environmental radiation dose commitment" should be
defined, (p-27)
Staff Response - The definition of "environmental radiation dose
commitment as used in the Guidance is: "the total dose accumulated
by all individuals in a given population over a designated period of
time."
40. Department of Energy
This sentence has a syntax problem. The conjunction "and" should
be changed to "since," or, better, dropped to form two sentences. The
content of this sentence is important and deserves greater emphasis
than it is given, (p-27, lines 23-25)
Staff Response - The sentence reads as intended, and represents
parallel conclusions.
41. Department of Defense
The use of "over a prolonged period of time" is another example
of using non-specific quantifying phrases and has no meaning—is it a
year, 10 years, lifetime or what? (p-28, line 5)
Staff Response - The phrase is purposely non-specific to avoid
the impression that only a lifetime exposure is significant.
60
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10
42. Department of Energy
A "prolonged period of time" should be more explicitly defined.
(p-28, line 5)
Staff Response - See comment 41.
43. Department of Energy
"Bites and stings" should be attributed to venemous animals and
insects. Electric current is not hazardous when confined to "home
wiring and appliances." The fatalities should be attributed to
electrocution or electric burn or shock, (p-28, lines 6-7)
Staff Response - The meaning would seem clear to the intelligent
layman.
44. Department of Energy
It should be made clear that the purpose of these soil
measurements is to locate the specific areas of contamination.
(p-29, lines 2-3)
Staff Response - We agree.
45. Department of Energy
"Suggests" may be too weak a word; "recommending" might be more
appropriate, (p-29, line 12)
Staff Response - We agree.
46. Department of Energy
Specification of particle size seems an unnecessary complication
for a "screening level" already burdened with many conservative
assumptions, (p-29, line 14)
Staff Response -^ The specification limits the inclusion of large
particles, and follows the definition of "agronomic soils."
€1
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11
47. Department of Energy
This paragraph is an example of the imprecise wording that
deprives the Guidance of practical utility, (p-28, lines 18-23)
Staff Response - We believe the wording to be precise and the
intended meaning clear. The paragraph admonishes the implementing
agencies to consider all pertinent pathways.
48. Department of Defense
Overall, the chapter does not read well, is constructed poorly
from the standpoint of style and clarity, is imprecise and lacks
definite statements.
Staff Response - de gustibus non disputandum est.
49. Ilene Younghein
If we continue with our present nuclear energy plans, by the year
2000 we will have accumulated roughly 1.6 million pounds of
plutonium-including plutonium from breeders-according to estimates by
Glenn Seaborg. Even with 99.99 percent storage reliability, the
nuclear industry will release 160 pounds of plutonium each year. If
1.6 micrograms can cause cancer in a non-smoking adult - that is
enough to provide minimum potential lung cancer doses for about 15
times earth's present population.
Staff Response - Control and accountability of plutonium is
orders of magnitude better than the number stated, and is expected to
improve. The assumption that the entire release is transferred
through the environment to become the body burden for humans is
patently absurd. Transfer and uptake mechanisms are discussed in the
Technical Summary.
50. Ilene Younghein
Section 1.2 is vague. You said more recent weapons tests have not
added significant amounts to this level. What do you mean by
significant? Also what do you mean by significantly higher amounts in
refering to Bikini and Enewetak. Is that a way of avoiding how much
radiation is really there. Other mushy language is about the
underground detonation where you said that it is contained below the
earth's surface and is not expected to be readily avilable for uptake
by humans. Areas of high concentrations may be well documented, but
long terra health effects have not. The fact that most of the
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12
contamination is on Federally owned property says .something about the
carelessness to which public trust, is carried out. Everybody's land
is nobody's land.
Staff Response - a) "Significant" changes of environmental
contamination levels are usually considered to involve,increases of at
least twice the standard deviation of observed values.
b) Data for Enewetak atoll are given in Annex I.
c) The guidance is concerned specifically with doses to humans
and considers availability in those terms.
d.) The subject of long-term health effects resulting from
exposure to alpha particle radioactivity is under continuing review.
The guidance is based on' best available'current information.,
e) Production of plutonium, fabrication, and testing of weapons
are necessarily carried out in areas restricted to the public. The
Federal government purchased land for these specific purposes,
including surrounding "buffer zone" areas.
51- Ilene Younghein
Section 1.3, Other modes of resuspensipn of airborne particles
could be traffic, and plowing. "Discrete particles" is cosmetic
language. Separate particles would be a better use of the language.
No way can a particle of Pu 239 be called discrete. The statement
that the uptake by plants is relatively small is misleadirig. Plants
have been know to accumulate plutonium and concentrate it in.their
systems, and your statement that most animals, including humans have a
high discrimination factor against transfer of these elements into
body tissue is questionable. For sure, plutonium deposited on the
skin can cause cancer.
Staff Response - a)
man-made disturbances.
Traffic and plowing are examples of
b) Discrete is' not discreet (see dictionary).
c) The agency staff has considered all available information on
plant uptake. No reference was found to'substantiate concentration in
plants.
'd) Discrimination factors for biological uptake of ingested
plutonium are based on best available information.
e) There is no evidence that plutonium deposited on the skin can
cause cancer. Even if plutonium penetrated the skin the expected
result would be development of a foreign body granuloma or fibroma.
(See Lushbaugh, et al., Ann. N. Y. Acad. Sci. 145:791-797 (1967))
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13
52. Ilene Younghein
The makeup of your Working Group is suspect. Both ERDA and NRC
have and still actively promote nuclear energy. NASA uses nuclear
satellities, and the Department of Defense is responsible for most of
the contamination from the transuranic elements. Under the DOD we
have gone from the average fallout of .06 pCi/g to 18,000 pCi/g in
Nevada. This may be a reason for the high cancer rates in Nevada.
Plutonium levels now measure 1000 pCi/g at Rocky Flats, Colorado.
Cancer and leukemia rates have reached almost epidemic proportions in
North Denver, and in Mesa County - home of the uranium tailings.
Rather than try to cut down on radioactive contamination, the State of
Colo, has accommodated themselves to it, and raised their levels of
allowable pollution to twenty times fallout.
Sjiaff Response - a) The function of the Working Group was to act
in an advisory capacity and to make available to the EPA the technical
expertise of these agencies. The Federal Radation Guidance is subject
to interagency review and signed by the President.
b) The past or present association of an individual with nuclear
energy or nuclear weapons is not considered a deterrent to his
providing developing technical expertise relevant to radiation
protection.
c) The statements referring to cancer and/or leukemia
"epidemics", and the rationale for the current Colorado standard are
irresponsible and not based on fact.
53. National Council on Radiation Protection and Measurements
The documentation and information used from the reference is
frequently in error. There are a number of cases where the reference
does not discuss the subject matter at hand. In several others, a
review of the reference leads to conclusion different from those
quoted. In at least one case, a qualitative statement was made about
the results when a quantitative statement is needed to justify the
conculsion.
We recommend a vigorous review of the references and the material
used in the report in order to provide an accurate indication of the
important material.
Staff Response - In the absence of more definitive information,
no response can be provided for this comment.
64
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14
54. N.Y. Federation for Safe Energy
The proposed guidance is incomplete in that it does not take into
account the many sources of radiation individuals are exposed to due
to industry and commercial uses of radioactive products, as well as
additional radioactivity released from operating facilities such as
Millstone and Fort St. Vrain, which are just two recent incidents that
come to mind.
Staff Response - The guidance provides recommendations only for
transuranium elements in the general environment. None of the sources
terms mentioned are applicable.
55. Jefferson County Health Department
'Why are dosage rates (page 17) expressed in terms of millirad per
year (mrad/yr), since the term "rad" does not include the relative
biological effectiveness factor for the type of radiation involved?
The U.S. Environmental Protection Agency (EPA) water quality standards
published in 1976, for example, give standards for exposure to
radiation in millirem.
Staff Response - The Guidance limits are applicable to alpha
particle emitters. Therefore both dose and risk estimates are
expressed in a more fundamental physical unit, the rad, which is a
measure of the specific energy imparted. This approach is more
straightforward and periodic revision of the Guidance will not be
needed to account for differences between various kinds of radiation.
Further information on health effects will, however, be factored into
these guides as the need arises.
65
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3. RESPONSE TO COMMENTS ON ANNEXES I THROUGH ¥1
3.1 Annex I - Transuranium Elements in the Environment
Comments of an editorial nature were accepted where appropriate
and will be reflected in future publications of this Annex. Reference
22 of Annex 1 should be changed to: Douglas, R.L. "Data Report -
Levels and Distribution of Environmental Plutonium Around the Trinity
Site," ORP/LV-78-3, USEPA, Office of Radiation Programs, Las Vegas
Facility, Las Vegas, Nevada 89111 (1978).
1. Department of Energy
Although included in the list on p. 1-1, the possibility of
future accidents involving nuclear weapons and satellite power sources
is not discussed. This iss based on past experience, a more probable
"source for future release of the transuranium elements to the general
environment" than "operations associated with the Light-Water Reactor
Fuel Cycle." (p-1)
Staff Response - The relative probabilities of future releases
from these sources are not well known but we agree that future
uncontrolled releases to the general environment could occur from
operations other than those associated with the Light-Water Reactor
Fuel Cycle.
2. N.Y Federation for Safe Energy
Page 3 states the major portion of the transuranium elements in
the environment is the result of nuclear weapons tests during
1945-63. Was 1963 the last nuclear test that was considered in total
fallout? If so, the French test of 1976, the "dirty" Chinese tests of
1976 and 1977, should be included, as well as any radioactivity
released by the Cosmos crash last month, (p-3)
Staff Response - Tables in Annex 1 include measurements on
plutonium in fallout through 1975. Tests after 1975 have not
significantly altered the environmental levels of plutoniu® in soil.
The evaluation of existing environmental contamination given in
the technical documents is not intended to be exhaustive, but rather
to give a sussnary of the current status. Inclusion of specific events
is not pertinent to the intent and rationale of the guidance.
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3. Department of Energy
The last listing in the inventory column, "4,000 (Pu-238)" is not
correct. It was probably intended to be "4000 (Am-241)."
Staff Response - "4,000 (Pu-238)" should be changed to "4,000
(Am-241)."
4. Department of Energy
The relationship of the Tonopah Test Range to the Nevada Test
Site should be clarified, (p-9)
Staff Response - The Nellis Air Force Range nearly surrounds the
Nevada Test Site forming an exclusion area 25 to 100 kms wide
(ref. 29, Annex 1). The Tonopah Test Range is located in the
northwest corner of the Nellis Air Force Range and is not considered
to be part of the Nevada Test Site.
5. Department of Energy -
The old boundaries within the new boundaries of Rocky Flats are
confusing and should be deleted or explained. (Fig. A 1-6)
Rocky Flats boundaries should be updated.
Further explanation is required for the numbers on this figure,
some of which are isopleths and some of which are sampling locations.
More recent surveys show better estimates of these isopleths.
The statement that "plutonium in soil (offsite areas) is less
than 0.1 uCi/m2" is in apparent disagreement with Fig. A 1-7, which
shows a 0.5 uCi/m2 isopleth extending beyond indicated plant
boundaries. An up-to-date version of Fig. A 1-7 might eliminate this
problem.
Some attempt should be made to relate the 5 cm deep samples
discussed here to the 1 cm deep samples of the Guidance screening
level. It is otherwise possible to mistakenly conclude that the Rocky
Flats samples could exceed the screening level.
Staff Response - An updated map of the Rocky Flats site showing
the new boundaries and isopleths in units of uCi/m2 is shown in fig.
2.4-24 of the "Draft Environmental Impact Statement - Rocky Flats
Plant Site, Golden Colorado", ERDA-1545-D, (Sept. 1977). This is
reproduced on the following page.
88
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>/V GREAT ""-•-
J*' \WESTERN •"—•.. ^"-..,
-^J«ESERVgR -X.s X
0.05 \ IU
EROA PROPERTY
BOUNDARY
FIGURE 3 Plutonium-239 Contours Around Rocky Flats OiCi/m2)
(adapted from Kiey, 1970)
-------
The relationship between a 5 cm deep samples and a 1 c» deep
sample will depend on the mixing of soil that has occurred. For an
undisturbed site about half of the activity in the top 5 c* would be
expected within the top 1 cm (Annex I, Table Al-2)
6. Department of Energy
"Wet weight" or "dry weight" should be specified if these value*
are to be meaningful. (Table A 1-10)
Staff Response - Average concentrations in Table A 1-10 are in
terms of wet weight.
7. Department of Energy
Data on core sediment sample has no value without specification
of sampling depth. (Table A 1-11)
Staff Response - Core samples were collected by the Hound
Laboratory and are believed to be 1 foot cores.
8. Department of Energy ,
It would be helpful to know over what period of time air and
rainwater samples were averaged. (A 1-12)
Plutonium in rainwater cannot be expressed in pCi/ra .
(Table A 1-12)
Staff Response - Samples represent annual averages. The
Plutonium "concentration" should be plutoniuas "deposition" in rainfall.
9. N.Y Federation on Safe Energy
The referenced proposed Guidance is incomplete in listing sources
of radioactive materials in the environment now. Table Al-15 lists
underground testing conducted off the Nevada Test Site, ref. US AEC
Jan. thru Dec. 1973. Since the proposed guidance was not issued till
Sept. 1977, why wasn't a recent listing used. Even the one that is in
the proposed guidance is incomplete. One really "dirty" (and most
likely embarrassing) NTS test Dec. 18, 1970 "Baneberry" is not even
listed. This released a cloud of radioactivity 10,000 feet above the
surface exposing some 86 persons to radiation. In addition, since
1973 there have been at least 40 - 50 "announced" tests. (Al-15)
Staff Response - Underground nuclear tests on federally owned
sites have not released transuranium elements to off-site areas in
quantities that lead to significant doses compared to guidance
recommendations.
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- -,•<•-- 5 -- -.-. - ...
10. Department of Energy-,
Referenpe should be given. (Table A 1-24) 1
Soil data have no value without specification of sampling deoth
(Table A 1-24). y *'
Staff Response - References for Table A 1-24 and for Table A-1-25
are 10, 13, and 24.
The soil samples in Table A 1-24 were collected to^.S cms.
11. Colorado Department of Health
Throughout the supporting documentation regarding airborne
concentrations of plutonium as related to soil contamination levels
only ERDA (now DOE) data has been used. Following the EPA hearing
held in Denver on January 10, 1975, at your request the Department's
air surveillance data for the Rocky Flats Plant environs was
provided. On previous "rough" drafts of the proposed guidance
document we have commented that data other than that provided by the
ERDA facility have not been referenced or used. As the State's data
identifies levels a factor of 2-8 higher than the values provided by
the Rocky Flats Plant's own surveillance, you underestimate the
associated health risk and the costs, of remedial action. We urge vour
use of all pertinent data in your evaluation and assessment of the
guidance impact.; ,
Staff Response - Table 1 is a partial summary of some of the
Colorado Department of Health data on air concentration levels of
Plutonium taken, from "U.S. AEG Rocky Flats Plant 1971 Environmental
Surveillance Summary Report" Colorado Department of Health, Division
of Occupational and Radiological Health, Denver, Colorado, and
succeeding volumes in this series through 1974.
The agency staff recognizes that (the data reported by the
Colorado Department of Health are generally higher than similar data
reported by the Rocky Flats Plant. Such experimental differences may
be^indicative of systematic differences in the sampling and analysis
methods, actual variations .between sites, differences in measurement
interval, short-term fluctuations, or other reasons. The accuracy and
precision, of environmental measurements is necessarily limited and
such constrants raust.be recognized. However, it is important to
recognise that none of the data presented by the State of Colorado for
offsite areas around the Rocky Flats site indicate that air
concentrations of the transuranium elements exceed the agency's
screening level. Therefore, few, if any, remedial actions are
expected tp be necessary for .this site, and the costs have not been
underestimated.
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TABLE 1
Concentration of Plutonium in Air - Rocky Flats Site, 1971-1974
- Colorado Department of Health Stations -
Sample Location
On Site
Stations
East of the
Plant
Local (b)
Off Site
Stations
Remote
Station
D-l
D-2
APC-56
D-3
D-4
APC-2
APC-15
APC-16
APC-17
APC-22
APC-29
APC-42
APC-81
APC-108
1971
(fCi/m3-)
0.31
0.34
1.8
10.
7.3
___
0.08
0.08
0.07
0.07
___
Plutonium Concentration in Air
1972 1973 1974
(fCi/m3) (fCi/m3) (fCi/m3)
1.4
0.69
2.3
4.5
5.5
0.04
0.06
0.06
0.04
0.08
0.06
0.07
0.11
0.59
.2.9
3.2
0.07
0.05
0.06
0.06
0.05
0.14
0.07
0.23
0.05
0.31
0.72
0.17
3.8
1.3
0.05
0.25
0.08
0.07
0.10
0.07
0.13
0.32
0.14
Ca) "USAEC Rocky Flats Plant 1971 Environmental Surveillance Summary Report"
Colorado Department of Health, Divison of Occupational and Radiological Health, Denver Colorado, and
also succeeding volumes in this series through 1974
(b) Located in Metropolitan Denver Area; to the east and southeast of the Rocky Flats Site
to
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12. Jefferson County Health Department
This report states that "less than 10 microcuries of plutonium
were released from plant stacks and vents to the atmosphere in 1975."
However, on one day in 1957, an average of 948 picocuries per cubic
meter were released from one stack to the atmosphere for a total
amount of about 5,000 microcuries in one day (3). In considering the
rezoning of agricultural lands adjacent to the plant site for
residential use, such accidental releases of plutonium in such large
amounts must be evaluated.
In the third paragraph on this page, reference is made to figures
A 1-6 and A 1-7 which show plutonium values in soils to a depth'of
five centimeters. Why was a more recent report giving plutonium
concentrations in respirable dust on the surface of the soil not
cited, instead of this soil inventory figure (8)? It is noted that
americium-241 within the site boundaries are about 10% of the
plutonium-239 values. In a few decades, the americium will present as
much radiation hazard as the plutonium. I'm not certain that this has
been considered in calculating the guidelines.
Staff Response - The most significant releases of plutonium from
the Rocky Flats Plant Site are still believed to be the result of
leaking oil drums containing plutonium as a contaminant. However,
surveillance measurements cannot distinguish between plutonium from
stack releases or from the leaking oil drums. In practice, all
plutonium in soil around the plant, regardless of the source, has been
evaluated.
The measurement of plutonium concentrations in respirable dust
has not yet been accepted as an appropriate measurement procedure
useful for the estimation of hazards associated with plutonium in soil.
Americium-241 concentrations in soil and other environmental
media were considered in the proposed guidance.
13. N.Y Federation on Safe Energy
I would question why, at sites listed in the proposed guidance,
information is lacking, such as elements released to air (pg. 152) at
Argonne National Lab., and (pg. 55) water at Oak Ridge Facilities .
If EPA wants to set meaningful guidelines, Step One is to see where
you are now. This cannot be done with speculative and/or partial
information.
Staff Response - The agency staff believes that there is
sufficient information on environmental levels of the transuranium
elements to permit the issuing of Federal Guidance at this time.
73
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14. Ilene Younghein
The Enewetak Islands not likely to be reoccupied were not named.
p-51 "these high levels are believed to have been caused by analytical
errors." Perhaps it would be wise to find out. p-54,55 finds soil
samples taken at different depths making it hard to compare. Why was
plutonium concentrations in water at White Oak Creek Clinch River not
published, (p-46)
Staff Response - The information given is quoted from available
technical reports. It is relevant only to the extent that is provides
an indication of the existing environmental contamination levels at
various sites.
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3.2
Annex-II Environmental Transport and Pathways
1« Department of Defense
Department of Energy
An arrow head is missing between "water" and "sediments."
IFig. A 2-1).
Staff Response - Correction to Fig. A 2-1 is acknowledged:
2. Department of Energy '• ,...,........,. ,.. -..-• ..... .•.-.•...-._-
The implication that environmental plutonium will usually be
present in oxide form has sometimes been assumed, but without proof.
References for these statements should be given, (p.3)
Staff Response - Price and Ames have reported the presence of
Pu02 under both alkaline and acidic oxidizing environments. Their
observations were made approximately 20 years after the acidic
radioactive waste was disposed to the alkaline soils. Tamura inferred
the presence of Pu02 in soils from the Nevada Test Site
Theoretical studies by Polzer and Rai and Seme have predicted PuO,
as the most stable plutonium compound expected to be present in soils.
ref;
S.M. Price and L.L. Ames, Characterization of Actinide-bearinff
Sediments Underlying Liquid Waste Disposal Facilities at Hanford
IAEA-SM-199/87, International Atomic Energy Agency, Vienna (1975).
T. Tamura, "Distribution and Characterization of Plutonium in
Soils from Nevada Test Site," in The Dynamics of Plutonium in
Desert Environment. NVO-142, USAEC, Las Vegas. Nevada""(1974y."
W.L. Polser, "Solubility of Plutonium in Soil/Water Environment "
ln Procee<*ings of Rocky Flats Symposium on Safety in Plutonium
Hana£iag_ Facilities, OWF-710401 rS5"Ch55rcal Company, Rocky
Flats Div., Golden, Colorado (1971).
D. Rai and R.J. Seme, "Plutonium Activities in Soil Solutions
and the Stability and Formation of Selected Plutonium Minerals "
J. Environ. Qual. 6, p.89 (1971).
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3. Department of Energy
"In liquid form" is probably intended to mean "as a solution."
(p-3, line 12)
Staff Response - Wording changed to read "as a solution."
4. Department of Defense
Department of Energy
A 10 um diameter particle does not have an AMAD of comparable
size, thus it is unlikely that particles in this upper range would be
termed respirable. (p-3)
A 10 um diameter particle of plutonium oxide will have an
aerodynamic diameter of about 30 um, which is well beyond what is
usually considered the respirable range, (p-3)
"wet and dry deposition" should be defined, (p-3).
Staff Response - We agree. The wording of lines 17-22 should
read:
Airborne releases of the transuranium elements will generally be
in the oxide form and contain a substantial percentage of particles
within the respirable size range. Because of the small gravitational
settling velocities of the respirable size particles, they can be
transported long distances by air currents before attaching to
surfaces or being removed by precipitation.
5. Department of Energy
Unnecessary detail about Pu02 and hydrated Pu02 may be
confusing if not further explained, (p-4)
Staff Response - In future revisions of the document, details of
the interaction of Pu02 with soil particles will be transferred to
Section 2.2. Soil Transport in order to minimize the confusion of the
reader.
6. Department of Energy
It is implied that we can expect considerable progress in the
understanding of resuspension phenomena as a result of recent
studies. Actually, such studies have been conducted for many years
and there has been no acceleration of work over the past several
years, (p-4)
76
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Staff Response - No such implication is meant. It is for this
reason that the agency staff has-selected to employ, with some
modification, a relatively simple relationship for describing
resuspension rather than attempt to incorporate many of the factors
listed in Table A 2-1.
7. Department of Defense .' _ •
Department of Energy
What is depicted in this table are not the "factors influencing
wind suspension9' but factors that influence the resuspension of
materials by wind action. (Table A 2-1)
A better title would be "Factors Influencing Resuspension by
Wiad." "Meteorology," not "Mefcerology." (Table A 2-1)
Staff Response - The caption of Table A 2-1 should be changed to
read "Factors Influencing Resuspension by Mind."
8. Department of Energy
The data summarized in this table are of little value without
more adequate definition of the terms used and without more
information concerning the circumstances under which the data were
obtained. (Table A 2-2)
Footnotes could easily be mistaken for reference numbers.
Staff Response - The staff does not agree that the data
summarized in Table A 2-2 are of little value. Unncessary details
about experimental conditions would only confuse the reader. As
discussed in the test, the purpose of Table ,A 2-2 is to provide the
reader with a feeling for the range of resuspension factors, for newly
deposited material. Measurements were made under conditions of wind
arid mechanical disturbance. , • ;
9. Department of Defense.
Department of Energy
"over a period of time" is not clear. (p-89 line 20)
The very vague statements about solubiiizatiom of plutonium oxide
should be referenced and placed in some more precise time frame than
"over a period of time." (p-8)
-------
Staff Response - Several mechanisms have been suggested (see
references below) which can lead to increased solubilization of
plutoniuB after its release to the environment. Included among these
are: 1) chelation by organic constituents in the soil or through the
addition of fertilizers, 2) increased root absorption zone contact as
plutoniuB migrates down through the soil, 3) increased radiocolloid
size due to aging, and 4) the long-term action of micro-organisms
present in the soil.
Since ouch of the research into these mechanisms is in the early
stages, a quantitative discussion of the time required for such
transformations is not currently possible. However, preliminary data
have not deaonstrated a rapid transformation to occur under conditions
generally encountered in the environment. It is most likely that, if
these transformations occur at all, they would take on the order of
years to decades.
ref;
J.M. Cleveland and T.F. Rees, "Investigation of Solubilization of
Plutoniun and Anericium in Soil by Natural Humis Compounds," Env.
Sci. Tech. 10, p.802 (1976).
E.A. Bondietti, S.A. Reynold, and M.H. Shanks, Interaction of
Plutonium with Complexing Substances in Soils and Natural Waters,
IAEA-SM-199/51, International AtomTc~EnergyAgency, Vienna (1975).
E.M. Ronney, H.M. Mork, and K.H. Larson, "Persistence of Plutonium
in Soil, Plants, and Small Mammals," Health Physics 19, p.487
(1970).
W.V. Lipton and A.S. Goldin, "Some Factors Influencing the Uptake
of Plutoniura-239 by Pea Plants," Health Physics 30, p.425 (1976).
K.R. Price, "A Review of Transuranium Elements in Soils, Plants,
and Animals," J. Envir. Qual. 2, p.62 (1973).
F.H.F. Au, W.F. Beckert, and J.C. McFarlane, Plutonium Uptake
bya Soil Microorganism, Aspercillus Niger, NERC-LV-539-37, USEPA,
Las Vegas, Nevada (1976 ) ~~"~
10. Department of Energy
The relationship between specific activity and oxide solubility
should be stated more specifically, (p-9)
Staff Response - Increased solubility of Pu-238 versus Pu-239 may
be attributable to the fact that the alpha radiations from Pu-238 are
more energetic than those of Pu-239. This may contribute to greater
aggregate recoil or ejection of clusters of atoms from the surface of
the particle.
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11. Department of Energy
It is not at all certain that "the resuspension of soil .
particles. .. will be the principal mode of farther environmental-
transport." It seems more likely .that transport in unvegetated areas
will be by saltation or surface creep, and water movement of -sediments
may be of primary importance in erosion areas. In heavily vegetated
areas, water transport will probably be of.-. primary importance. (p-9)
Staff Response - Mechanisms other than resuspension sr© -also
responsible for the environmental transport of radioactive particles,
and on a mass transport basis are more important than resuspension.
Emphasis was placed on the resuspension of soil' particles 'because
inhalation is generally the most important pathway for environmental
plutonium. The staff does acknowledge that these other mechanisms
should be discussed and perspective given to their potential impacts.
12. Department of Defense ' .
Department of Energy
Aqueous Transport ; Are these four points subjective
determinations by EPA or do they result fro® referenced works?
st.< te. (p-10)
The four points listed should be supported by references.
Staff Response - References:
Point #1
If so,
J..A. Hetherington, D.F. Jerries, M.B. Lovett, Radiological
Impacts of Releases from Nuclear Facilities into Aquatic '-Environ-.
ments, IAEA-SM- 198/29, International Atomic Energy Agency, """"
Vienna (1975).
K.C. Pillai and E. Mathew, Plutonium. in ..... Aquatic_Envirotment8--
Its Behaviors Distribution,__ai^^gnl!Hca'nc'ea 'lAEA-SM-199/27 ,
International Atomic Energy Agency, Vienna (1975).
Point #2 and Point #3 - ' . , ' "
H.D. Livingston and V.T. Bowen9 .Contrasts Between the Marine and
Freshwater Biological Interactions of Plutonium and Americium,
HASL-315, Health and Safety Laboratory, USERDA, p.I-157 (1977).
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13.
Point #4
V.T. Bowen, H.D. Livingston, and J.C. Burke, Distribution of
Transuranium Nuclides in Sediment and Biota of the North Atlantic
Ocean, IAEA-SM-199/96, International Atomic Energy Agency,
Vienna (1975).
Department of Energy
"Concentration factor" requires definition (p-10, line 22).
Staff Response - Concentration Factor
pCi/kg (wet plant)
pCi/kg (water)
14. Department of Energy
The reference to Langham's "studies" at Thule is in error. There
is no mention of Thule in this paper, (p-10)
Staff Response - Reference to Langhara: USAF Nuclear Safety 65,
p.36 (1970).
15. Department of Energy
The postulated "limited mobility for environmental transport" in
aqueous systems does not take into consideration extensive data on
transport of sediments bearing radioactive materials in the Tennessee
and Columbia Rivers. Movement of plutonium on sediments has also been
demonstrated in several estuaries, (p-11)
Staff Response - The staff agrees that the wording should be
changed to reflect the fact that hydrological transport of plutonium
contaminated sediments occurs in marine and freshwater ecosystems and
has been responsible for transporting radioactive material as much as
several miles from its point of initial release. Since the
radioactivity is primarily associated with the bottom sediments, its
radiological significance in terms of dose to man has been generally
assessed to be small. As long as the water body is maintained at a
fairly constant level and large areas of the sediment bed are not
exposed and allowed to dry, thereby becoming a wind resuspension
problem, the radioactivity committed to the water will be bound in a
form which has little biological availability.
eo
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Department of Defense
Department of Energy
The PAID code is crucial to the derivation of the guidance, yet
it is not published. Because of the complexity of aerosol physics,
particle sizes and distributions, etc., it is really unfair to ask
that the general radiation industry accept on faith the assumptions,
parameters and other input used in the PAID code; it should be
available for review, (p-12)
No description of the PAID code is given here, or in Annex III,
and the only reference is to an unpublished document. Since the
specific numerical basis for this Guidance is all derived from the
PAID code, its unavailability prevents any verification of these
numbers, (p.12)
Staff Response - The PAID code is available as: Plutonium Air
Inhalation Dose (PAID), Technical Note ORP/CSD-77-4, USEPA, Office of
Radiation Programs, Washington, D.C.
17. Department of Energy ••''.-
It is implied that because the PAID code "assumes Og to be 1.5,"
it is never necessary to determine <^ . Since measurement of AMAD
provides the data required,
-------
3. the limited size distribution data obtained in the vicinity
of plutonium contaminated areas have been able to be fitted reasonably
well by a log-normal distribution..
ref;
M.W. Nathans, W.D. Holland, and H.C. Shaw, The Size Distribution
and Plutonium Concentration of Particles From the Rocky Flats
Area, TLW-6111, Trapelo/West, Division of LFE Corporation.
Richmond, Calif. (1971).
L.R. Anspaugh and P.L. Phelps, "Results and Data Analysis:
Resuspension Element Status Report" in The Dynamics of Plutonium
in Desert Environments, NVO-142, USAEC, Nevada Operation Office,
p. 265 (1974).
18. Department of Energy '•
This is a confusing paragraph that should be revised or deleted.
It is not made clear why the entire distribution need be measured, nor
how it is possible to do this if all samplers have an "upper size
cut-off." The reference to "resuspending soil" is confusing in this
paragraph which is otherwise devoted to measurements in air.
(p-13, line 14)
Staff Response - The reason for this admonition is the fact that
most lung models in general use assume that the value of the ambient
air activity (which is supplied as input to the particular model) is
the total air concentration. These models then proceed to fractionate
the total concentration among the various lung compartments. In order
to be consistent with this assumption, measurement should encompass
the widest range of particle sizes possible. The interested reader is
referred to the following reference comparing the collection
efficiencies of several commonly used methods.
ref: Wedding, J. B., McFarland, A. R., and Cermak, J. E., "Large
Particle Collection Characteristics of Ambient Aerosol Samples", Env.
Sci. and Tech., 11, p. 387 (1977).
19. Department of Energy
This is an over simplified interpretation of a very limited
experiment. The field was small and the range of meteorological
conditions limited. Sweeping conclusions based on this single
experiment are hardly justified.
-------
However, much higher exposures would have been inferred had EPA
employed the data collected at 7.6 m from the edge of the field rather
than utilizing the data collected at 30 m from the edge of the field.
It is not necessarily true that an individual might not spend a great
deal of time at the edge of the field, since farmhouses are often at
the edges of fields. :.
(p-14, line 14)
Surrounding areas downwind would be expected to experience some
increased exposure due to "these operations." The Guidance contains
numerous sentences in which the word "significant" is employed without
definition. (p-14, lines 20-21)
Staff Response - Ideally one would like to have more data
encompassing other types of soils and different meteorological
conditions before attempting a scoping calculation of this kind.
However, there is a paucity of such data. This calculation was meant
to put into perspective the relative impacts of wind versus mechanical
disturbance of a field with surface contamination roughly
corresponding to the screening level suggested in this Guidance. The
air data reported for 7.6 meters from the edge of the field was not
incorporated into the calculation because the authors had raised
doubts as to the precision of that data: "the large means and standard
deviations...for the sampler locations 7.6 m downwind from the edge of
the field were caused by 3 high measurements out of 27."
«*
Using the same data, Healy (ref. 37) has also attempted to
analyze the impact of agricultural operations. His objective was to
calculate the maximum soil concentration that would not exceed a
skeletal dose rate of 500 mrem/yr after 70 years to an individual at
the edge of a contaminated field. He concluded that 14 uCi/m2 would
be the maximum allowable concentration for a 1000 m wide field if
plowing were performed 40 hr/year. Extrapolation of Healy's data to a
field at the screening level of 0.26 uCi/m2 results in a projected
dose rate of 9.2 mrem/yr after 70 years or 0.5 rarad/yr (based on ICRP
Publication #26). This dose rate is a small fraction of the 3 mrad/yr
limit recommended in this Guidance and, therefore, would not present a
serious risk to individuals in the vicinity of the field.
20. Department of Defense
Department^ of Energy
A subjective conclusion that cannot be supported. If a one-time
cultivation results in a many-fold increase inhalation hazard, one
could just as easily conclude that the second-time disturbance could
also cause an increase, (p-14, line 18) !,
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10
If the first cultivation cycle resulted in a 30-fold increase in
air activity, it appears questionable to conclude that subsequent
cultivation "should not lead to significant increases."
(p-14, line 18)
Staff Response - The document did not conclude "that a one-time
cultivation results in a many-fold increase in inhalation hazard."
The analysis showed that, although the air concentration increased
during the various agricultural operations, the yearly average
concentration was increased by less than a factor of 2 for the tractor
operator (over that from wind resuspension) and by only 10% at a
location 30 meters downwind from the edge of the field.
21. Department of Energy
Assuming the maximum indicated resuspension fraction of 10~2,
passage of 100 cars would leave 37% of the original contamination on
the road surface. Is this "a small fraction?" (p-15, line 3)
Staff Response - The conclusion that only a small fraction would
remain after the passage of 100 cars was taken from the original paper
of G.A. Sehmel. That conclusion, however, does seem to be an
overstatement by the author.
22. Department of Defense
Department of Energy
Distinguish between "uptake" and "uptake factor" throughout the
section. Is one actual amount and the other a percent of that
available or what? (p-16)
Throughout Section 3.2 the words "uptake" and "uptake factor" are
employed in an ambiguous manner. They should be replaced by more
precise and carefully defined terms, (p.16)
Staff Response - "Uptake" refers to the amount of transuranium
material retained within the plant or animal.
"Uptake Factor"
pCi/g acceptor
pCi/g donor
23. Department of Energy
The assumption that "foods from other areas not as highly
contaminated will make up part of the diet" might not be true of a
"critical segment" of small farmers and home gardeners.
(p-17, lines 1-3)
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11
Staff Response - The assumption that "food from other areas not
as highly contaminated will make up part of the diet" was applied only
to estimating annual intakes for the general population. It is true
that farmers and home gardeners who raise crops for their own
consumption on contaminated land may have higher annual intakes than
the general population and would have to be considered as a "critical
segment" of the population when applying this Guidance.
24. Department of Energy
It should be clarified that 1.6 pCi and 2.6 pCi are estimates of
fallout plutonium absorbed from the gastrointestinal tract into the
blood. The word "intake" might be misinterpreted as "ingestion."
(p-17, line 5)
Staff Response - The above DOE statement is incorrect. According
to ref. 28, "the annual intake during 1972 was 1.6 pCi, due to 35% to
grain products, 20% each to vegetables, fruits, and meats, and less
than 4% to dairy products. The annual intake in 1965 was estimated to
be 2.6 pCi".
25. Department of Energy
The "extreme assumptions of soil consumption rates...required"
should be defined. Pica in children is characterized by "extreme"
behavior, as discussed at some length in ref. 37 of this Annex. Might
these children not qualify as a "critical segment?" The importance of
a more precise definition, in the Summary Report, of "critical segment
of the exposed popluation" is emphasised by questions such as this.
(p-17, lines 23-25)
Staff Response - Pica in children iis not normal behavior and
would persist for a relatively brief period of time. Such isolated
cases do not constitute a "critical segment" of the population.
The intent of the Guidance is to limit the risk from chronic
exposure to the transuranics to an acceptable level. In, the case of
ingestion9 the limit is expressed as the 70 year bone dose rate of
3 mrad/yr. Although acute exposures can always be postulated,which
exceed the normal chronic exposure levels, these must be analyzed in
terms of the projected 70 year bone dose rate. If such projections do
exceed the 3 mrad/yr (70 year), then the intent of the Guidance
is that remedial action should be taken.
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12
26. Department of Energy
The reference to "short residence time of plutonium in the
gastrointestinal tract" is confusing and should be deleted, since
radiation dose to the tract from alpha emitters is not considered
significant, (p-18, line 1)
Staff Response - Sentence changed to read: "However, for the
pathway to be as significant as the inhalation pathway, extreme
assuaptions of soil consumption rates would be required. This is
because of the low transfer of plutonium across the gastrointestinal
tract and the radiation dose to the tract from alpha emitters is not
considered significant."
27. Department of Energy
This sentence seems to'say that a resuspension factor, .based on
repeated Measurements over a long period of time, can be used to
calculate concentrations in air from concentrations in soil. But if
one has already measured the concentration in air in order to derive
the resuspension factor, why would it be necessary to calculate a
concentration in air? (p-19, line 7)
Rather than "areas" this sentence should refer to "points,"
since, by definition, the resuspension factor is based on a
measurement in air and soil at one point. In addition to the
"variability of the local meteorology," reference should also be made
to variability in mechanical disturbance.
Staff Response - Oftentimes in assessing the potential hazard of
existing contamination, resuspension data are available for several
locations on a particular site. However, data will not exist for
every point. The sentence in question refers to using such
measurements in evaluating the locations on the site for which air
data are not available. Whenever air measurements exist they are
certainly preferred over any calculational relationship between air<
and soil. On the other hand, the Agency feels that it would not be in
the interest of public health protection to postpone a decision on the
necessity of cleanup because air measurements at every point are not
available.
28. Department of Defense . -
Department of Energy
C.F. needs better definition particularly as to how it is
influenced by the depth of sampling and soil density, (p-19, line 2)
86
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13
This equation cannot be properly understood unless CvF. is better
defined. An explanation should be given for the effect of depth of
sampling and soil density,, and how these effects are applied in. C.F.-
(p-19, line 19)
Staff Response - C.F. is the factor which converts, a soil
concentration in units of activity/surface area to units of
activity/weight of soil. This is accomplished through the use of the
sampling depth and average soil density:
activity x 1 x 1
surface area sampling depth soil density
29. Department of Energy
activity
weight of soil
v It would .be helpfui to briefly .mention .the. methods by which -
airborne particles are measured in the National Air.-.Surveillance
Network (e.g., height of measurement). Without such a description,, it
is not clear whether or not. these measurements have any relevance to
the problem of transuranic inhalation. (p20, line 1).
Staff Response - Specific details as to methods of particle
collection employed in the National Air Surveillance Networks are
described in Fed. Reg. 36:22384-22385 (1971). Regarding the question.
of sampling height, no specific guidance is given as to the location
of samplers. It must be assumed, therefore, that the data reported by
the NASN is a composite of various sampling heights.
30. Department of Energy '
This sentences even with the explanation that, follows,, is not-
clear. (p-20, lines 10-14) t
The sentence beginning "This fallacy" would seem-to suggest ,that.-
there is only one fallacy involved in the mass loading approach.to
resuspensiori. Not included is any discussion of the usually erroneous
assumption that the particles measured in the air come from the
contaminated area. This is least apt to be true for the most
important (respirable) fraction, (p-20 line 10)
The derivation of the Enrichment Factor is :presented here with no
discussion of its theoretical inadequacies and its 'lack of ^ .
experimental verification. Since there.is no 'experimental supports
for the applicability of this •"Enrichment Factor,"'1 and since the
correction .which it introduces is .small <• compared to other . _
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14
uncertainties in resupension estimation,, and since it introduces
costly implementation problems, the Enrichment Factor should be
abandoned, (p-26, line 17)
If retained, the assumptions implicit in the Enrichment Factor
should be stated. These are: (1) All of the smaller particle sizes
in the soil are resuspended with equal probability; (2) all of the
soil particles in the air sample arise from the contaminated area.
The last particles, once airborne, are fractionated in size by
deposition and that the smaller particles can travel hundreds or
thousands of miles, (p-26 line 17)
The "equilibrium" implied is more correctly stated as one in
which the amount of material in each size range deposited should equal
the amount of material in each size range resuspended over the area.
Both deposition and resuspension rates change as a complex function of
particle size and wind speed, (p-29, line 7-10)
The comparison made in this sentence is not a valid one, because
the factor estimated from Equation 8 is in reality a soil resuspension
factor, while those to which it is compared are radioactivity
resuspension factors. It is one of the inadequacies of the mass
loading approach that these two kinds of factors not directly
comparable.
Department of Defense
Enrichment Factor: The enrichment factor section suffers from a
lack of discussion on its shortcomings, the assumptions in it, and
absence of experimental verification. Its desirability or utility is
not established, (p-26)
Staff Response - The above comments seem to reflect a basic
misunderstanding on the part of DOE and DOD regarding EPA's use of the
mass loading approach and the enrichment factor. The agency staff
wholeheartedly agrees with DOE and DOD fractionation of particle sizes
occurs with resuspension. Particles in the small or respirable size
range will be more susceptible to resuspension and will remain
airborne longer than the larger diameter particles. This
fractionation process will generate a distribution of airborne
particles different from the distribution of the bulk soil and,
therefore, the activity per weight of the suspended dust will be
different, from the activity per weight in the bulk soil. Depending on
the way in which the activity is distributed across the size range of
the bulk soil, there will either be an enrichment of activity per
weight in the suspended dust or a reduction of the activity per
weight.
88
-------
15
If the activity is predominately associated with the smaller, more
resuspendable soil particles, the suspended dust will have a higher
activity per weight than the bulk soil and vice versa. In any case,
it is unlikely that the activity per weight in the airborne material
would be the same as that in the bulk soil.
The mass loading approach by itself is not capable of considering
this fractionation effect and as such would predict the same activity
per weight for suspended and bulk soil. Because of this, the agency
staff has developed what it terms an "enrichment factor." The purpose
of this factor is to modify the basic mass loading formula in such a
way as to reflect the distribution of activity as a function of
particle size and the differences in size distributions between the
bulk soil and suspended dust.
Another point of confusion appears to be the context in which the
mass loading and enrichment factor were applied in the Guidance. This
calculational technique was used in the derivation of the soil
screening level. The agency staff feels that this level is
sufficiently low that costly monitoring of the inhalation exposure is
not required when surface concentrations are at or below this value.
In order to derive such a number on a generic basis and to insure that
this level is safe, some conservative assumptions had to be made,
e.g., it was assumed that the contaminated area was sufficiently large
enough that the airborne mass loading could be attributed to the
resuspension of soil from the contaminated area. The staff does not
dispute the point raised by DOE that, at real sites, injection of
suspended particles from noncontaminated areas can contribute to tht-
mass loading. If injection of these particles is occurring, then th2
mass loading calculation would predict higher than actual airborne
activity thereby, overestimating the inhalation exposure. For this
reason, the Guidance recommends the use of site-specific data to
assess the actual exposure hazard when soil concentrations exceed the
screening level.
31. Department of Energy
The data of Table A 2-3 are not the only data, nor the most
applicable data. Recent studies of Sehmel (ref. 39) show much poorer
correlation between predicted and observed results, (p-20, lines 8-^10)
Refernces to Anspaugh are incorrectly listed. (Table A 2-3)
More recent and more applicable data of Sehmel (ref. 39) should
be presented if this data is to be used. (Table A 2-3)
The mass loading approach is said to be supported by references
30 and 31. It should also be stated that more recent studies (ref.
39) have not supported the mass loading approach, (p-26, lines 4-8)
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16
Staff Response - From the above comments, it appears that the DOE
staff attribute considerable importance to ref. 39 and its conclusion
that the mass loading approach is not a viable predictive methodology.
Because DOE relies so heavily upon this reference, it is necessary to
point out some of the limitations and serious errors contained in that
reference.
First of all, as the author points out "Caution should be used in
interpreting these data. The ground surface contamination data are
limited in quantity and were not necessarily obtained in the same
areas where resuspension experiments were performed."
In addition to the uncertainties raised by the above statement,
the EPA staff questions the way in which the author interpreted his
data. The approach used was to make comparisons only on the basis of
extreme upper or lower observed limits. No attempt was made to define
an "average" case (e.g..,« the mean observed concentration) and make.
comparisons accordingly. The mass loading approach has been used in
the past only to calculate annual average air concentrations and was
used by EPA only in that context.
More importantly, the author's conclusion that the mass loading
approach did not predict the observed air concentrations was based
upon an apparently erroneous calculation. It appears that the
calculated values in Table 6 of ref. 39 are in error by 6 orders of
magnitude because units were not matched properly. As a~~resultY the
predicted values in Table 6 are too high. When the necessary
correction is applied, the predicted and observed levels show better
correlation. For the lower limit case of 27.73 ug/m3, the total
concentration (Pu-239) of respirable and nonrespirable particles is
calculated to be 1.9xlO~17 uCi/cm3. This calculated value can be
compared to the observed mean value of roughly 2x10"^^ uCi/cm3
(Figure 6 of ref. 39) or the lower observed limit of approximately
5xlO~18 uCi/cm3. Whether the sampling of the lower limit Pu-239
concentration coincided with the recording of the 27.73 ug/m3 is
impossible to say from the data as presented. However, it can be
justifiably argued that, within the limitations of the data, correct
interpretation should have yielded the opposite conclusion.
32. Department of Energy
Department of Defense
No evidence has been presented to support the conclusion reached
in this sentence that this approach "would seem reasonable." It
easily could be argued that the reverse is true.
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17
The aged source could contain a greater proportion of the transuranics
at greater depths in the soil profile and the resuspended surface
layer presumed to constitute the particle loading of the air would
less accurately reflect average soil content, (p-20, line 24)
Why does it "seem reasonable" that the error associated with
using mass loading approach would be least in "old" soils. With time,
it might seem reasonable that there are more transuranic elements at
depths than at the surface, thus causing the reverse of what is
depicted here, (p-20, last sentence)
Staff Response - The statement in question is based on the fact
that plutonium after it has been in the environment for a period of
time has generally been found to be associated with soil particles,
rather than existing as discrete plutonium particles. This
association is the result of various chemical and physical processes
which are collectively .termed "weathering." Once;it is'associated r
with the soil particles, the plutonium would be expected to resuspend
in the same manner as the surface soil and, therefore,its resuspension
can be related to the airborne dust loading. On the other hand,
freshly deposited activity may be more easily resuspended compared to
the bulk soil due to a higher percentage of plutonium particles in the
smaller size ranges. The decrease in the resuspension with time of
freshly deposited material is generally attributed to weathering.
The observation by DOE and DOD that there may be more activity:at
greater depths with the passing of time is not germane to the
discussion. The Guidance considers the erodible surface to be the top
one centimeter and relates only activity within that centimeter to the
airborne concentration.
33. Department of Energy
It is incorrect to state that the resuspension rate approaches
have "attempted to include in their formulations as parameters some of
the physical forces which control the resuspension phenomenon." The
Healy-Fuquay approach (ref. 32) to defining the rate was used because
of the lack of empirical data at that time. Present emphasis should
be placed on the more recent considerations, presented in ref. 37.
(p-23, lines 7-9).
It might be noted that more recent calculations by Healy in-ref.
37 did include variations in resuspension rate with wind speed.,
(p-24, lines 5-7)
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18
Staff Response - The Healy-Fuquay approach (ref. 32) assumed that the
rate of pickup of particles from a surface is directly proportional to
the ratio of wind forces to gravity forces on individual particles.
By taking the wind force on a particle to be proportional to the
square of the wind velocity and the particle area exposed to the wind,
an expression was developed for the rate of particle pickup.
34. Department of Energy
This sentence implies that there are formulations for predicting
resuspension that have "general applicability." Actually, none have
been demonstrated to have any "general applicability."
(p-24, lines 21-24)
Staff Response
No such implication is meant and in fact the text clearly states
"the general applicability of these formulations...has not been
demonstrated."
35. Department of Energy
Some qualification is needed of the statement that the weight
fraction of particles 10 urn is small in most soils. The tabulation
of published data in reference 37 shows that this fraction ranges from
a few percent in sands to several tens of percents in loams. Perhaps
undisturbed soil including aggregates is meant. Even here care must
be taken because soils lose their texture under long drought:
conditions, (p-27 lines 2-4)
Staff Response - The basis for the statement in the text was data
from sites of existing plutonium contamination where the less than
10 urn weight fraction has been small. In certain soils, especially
clays, this fraction can be larger.
36. Department of Energy
Methods for the analysis of particles within size ranges should
be described or referenced, (p-27, lines 22-25)
Staff Response - Various methods of particle size fractionation
are described in the technical literature. Since detailed
implementation of the Guidance is left up to the responsible agencies,
it is not appropriate to present such details lest it be misunderstood
as the only acceptable method.
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19
37. Department of Energy .
Subscript "i" misplaced, p-28, line 19)
Subscript "i" misplaced. (p-29, line 1)
Staff Response - Typographical errors are noted.
38. Department of Energy_
The parenthetical expression, "based upon certain assumptions
regarding prevailing meteorology," seems inadequate to convey the
factual information that the calculations employed annual wind roses
with joint wind speed, direction, and stability, (p-29, lines 24-25)
Staff Response - Such details were not felt to be necessary.
However, future revision will reflect this comment.
39. Department of Energy
An additional important assumption, not listed, is the assumption
that ingestion is a neligible risk compared with inhalation. This
sometimes questionable assumption may compromise the utility of the
.screening level concept. There would seem'to be no reason why
ingestion could not be considered as an additional factor in the
derivation of and probably accommodated in the screening level, thus
making it more a universally applicable concept. (p-30, lines 10-17)
Staff Response - Assessments of dose to populations surrounding
transuranium contaminated locations in the U.S. have concluded that
the principal exposure hazard is inhalation and that the ingestion
pathway is of little consequence. For this reason, the agency staff
derived the soil screening level on the basis of the inhalation
pathway as being the limiting case. It is possible in the event of
some future accident that the ingestion pathway could be of greater
significance. However the staff did not consider it appropriate to
derive the screening level for soil based upon a future occurrence at
some hypothetical location. The wide variation possible in crops
types and dietary habits makes such a generic derivation tenuous.
On the other hand, the agency staff has looked at the impact of
the ingestion pathway .on populations with various .postulated dietary
habits who are exposed to. land contaminated at the screening level. ..
Even for the situation of the serious home gardener, the dose rates
are not projected to exceed the limits recommended in this Guidance.
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20
40. Department of Energy
The value of 100 ug/ra^ needs to be more carefully evaluated and
the exact context of Anspaugh's and Healy's use of this number
described, (p-30, lines 21-25)
Staff Response - Anspaugh employed a value of 100 ug/m3 for the
airborne mass loading when calculating acceptable soil concentration
applicable to the Enewetak Atoll. His choice of 100 ug/m3 was based
upon an evaluation of values reported at rural sites in the
continental U.S. and Hawaii. Anspaugh concluded "this value should be
quite conservative for the Enewetak Islands and, therefore, allows
rooa for the uncertainty involved because the people themselves may
generate a significant fraction of the total aerosol."
Healy concluded that a value of 120 ug/m3 was sufficiently
conservative in calculating limiting soil concentrations by the mass
loading approach. His choice was based simply upon an interpretation
of EPA18 standard for airborne particulates .
^ * Department of Energy
Additional justification is required for the use, as an average
distribution over a 1-year period, of data measured by Chepil in a
dust storm, (p-31, lines 4-6)
Staff Response - Regretably there is a lack of particle size
distribution data covering the entire range of suspended sizes.
Primary emphasis has been placed on the measurement and control of
saall particles ( 5 urn) because possible deleterious effects can be
better correlated with the smaller sizes and because these sizes are
responsible for light scattering and visibility reduction. Few
researches have reported data for the larger particle sizes. An
effort was made in the text to compare Chepil's data with other
sources and, within the limitations of the data, there was reasonable
agreement.
42. Department of Energy
It is misleading to quote Sehmel'a data as indicating "28% of the
mass was below 10 urn", when, in fact, 23% was the maximum value
measured, under minimum resuspension conditions, and a value of 0.3%
was measured for the greatest mass loading, during dust 'storm
conditions. If use is to be made of this data it should not be used
selectively, (p-31, lines 11-13)
Staff Response - The data selected from Sehmel's report was that
which corresponded most closely with annual average mass loadings
reported by the National Air Surveillance Network.
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43. Department of Energy . ...
- Figure is not clearly titled or labeled,-and it is not-
referenced. (p-32, Fig. A 2-3)
Staff Response -•• Figure A 2-3 is referenced and discussed on
page 11-31.
44. Department of Energy
The acceptable air concentration here employed for derivation of
the screening level is based on an assumed AMAD'of 1 USB. In Annex V
(p. 6), "the Agency suggests that such a derived air concentration
limit be based on an activity median aerodynamic particle diameter
(AMAD) not to exceed 0.1 urn." This apparent discrepancy should be
explained or eliminated. A reference at this point ,to the discussion
in Annex V would seem appropriate. (p-339 lines 5-8) ' ..<•».•••
Staff Response - There is no discrepancy in using a 1 urn AMAB in
calculating the soil screening level and use of 0.1 urn AMAD for the
air screening level.
In situations where contaminated soil is the primary source of
the airborne activity, AMAD's of approximately 1 urn have been
reported. Whereas, when stack release are the primary source, auch
smaller AMAD's (approximately 0.1 urn) have been observed. In deriving
the soil screening level, which relates the airborne activity to the
soil as the source, a 1 um AMAD was used. On the other hand, in
defining an air screening level where the source is unspecified the
more conservative assumption of a 0.1 urn AMAD was used.
45. Department of Energy ' '"'".'•..
This Table requires a title and a reference and should presumably
be A 2-4.
It is not clear what these data represent. Are RF 1A, IB and 1C
aliquots of a single sample? What area is represented by these
samples? How were the sizes determined? Do they include aggregates?
What was the season of the year and the moisture content when
sampled? Can the results be reproduced if another sample is taken?
These questions are all important if the data are to be understood.
(p-34, Table A 2-3)
Staff Response - Table A 2-3 on page 11-34 should be renumbered
as Table A 2-4.
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22
Reference for Table A 2-4 is: D.E. Bernhardt, Evaluation of
Sample Collection and Analysis Techniques for Environmental Plutonium
ORP/LV-76-5, USEPA, Las Vegas, Nevada. ~~~ ~ :
Specific details of the sampling and analysis methodologies are
described on pages 20 through 45 of the above reference.
46. Department of Energy
If resuspension values have been reported for "existing sites" it
would seem important to list and reference them in the Annex. Are
these annual average factors or single measurements? (p-35, lines 6-7)
.Staff Response - Anspaugh (ref. 30) reported resuspension factors
of 3x10 "nfA and 2xlO-9m-l as a result of 17 months
of measurements at the Nevada Test Site.
m-9 R?dgers (ref' 4) reported a resuspension factor of approximately
10 *m A for the vicinity of Mound Laboratory based upon 3 years of
data. *
» Healy (ref. 37) calculated a resuspension factor of 2xlO~9m~1
for the Rocky Flats Plant site based upon 4 years of reported data.
47. Jefferson County Health Department
Environmental transport and pathways. On page 4, reference is
made to the work of Tamura, who has shown that plutonium bound to fine
particles (2-5 microns) was present as hydrated plutonium oxide. Is
hydrated plutonium oxide more likely to be taken up from the
intestional tract? I note in the last paragraph on this page that
such a wide range of values makes prediction of the resuspension
factor for a particular set of conditions a difficult task." The
guidance implies here that there is a variation of perhaps 100
Elsewhere in the EPA guidance, a variation factor of one million is
cited. This order of variation makes the use of such a resuspension
factor questionable.
Staff Response - Hydrated plutonium oxide is not more likely to
be taken up from the intestional tract. For example. Pu(OH)A has
been reported to have a solubility constant of 7xlO~56 which \s
indicative of a high degree of insolubility.
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23
The staff did not make use of the resuspension factor approach in
developing its guidance levels because of the wide variation in
reported resuspension factors. The range which is quoted as 10
covers virtually all reported values for the resuspension factor
regardless of the experimental conditions. Many of these were
obtained under conditions not applicable to environmental conditions.
When these values are removed from the data set, a narrower range of
values is obtained. The resultant range is still too large, however,
to be useful in developing a generic resuspension factor.
48. Jefferson County Health Department
Soil transport (page 8). This report states that plutonium
dispersed on the soil "has a tendency to bond chemically and/or
physically with the soil." Why then did the plutonium become airborne
from the soil containing plutonium in cutting oil at the plant site?
The report further notes that plutonium oxide is "generally considered
to be insoluble?', but "can undergo dissolution in neutral aqueous
media." The plutonium oxide particle dissolves producing plutonium
ions until the formation of a hydrated coating inhibits further
dissolution." "Plutonium ions formed during the dissolution can
undergo ion exchange reactions with the oxygenated ligands commonly
found in soil (e.g. silicates), and become sorbed onto the soil, or^
react with other agents present in the aqueous phase and form soluble
complexes." Since plutonium ions are able to displace most cations
such as calcium, magnesium, sodium, etc., it would seem that such
plutonium compounds would be available for uptake by plants. The
ability of seaweed to concentrate plutonium with a concentration
factor of about 1,000 is noted on page 10. Algae also have this
ability.
Staff Response - The plutonium did not become airborne from the
soil but along with the soil as a result of soil resuspension due to
wind erosion and mechanical disturbance.
Plutonium ions have been found to bond strongly with the soil
matrix through the displacement of other cations. This tendency to
bond with the soil matrix is one reason for the slow migration of
plutonium through soil and its low uptake by plants.
49, Jefferson County Health Department
The section on inhalation notes on page 13 that "when the aerosol
being sampled contains large particles of activity associated with
them the gross air activity being measured may be underestimated and
"if particles from the resuspending soil have disproportionate amount
of activity associated with them, the inhalation hazard could be
underestimated."
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24
Staff Response - The above statement was taken out of context.
It refers to the fact that air sampling, in order to be compatible
with the mathematical models describing lung deposition, must be
operated to collect the widest range of particle sizes possible.50.
Jefferson County Health Department
Enrichment factor (page 26). In reference to the use of
respirable dust samples, the report states at the top of page 27, that
"however, the weight fraction of -particles in the less than the micron
range is small in most soils, and sampling, separation, and analysis
techniques are correspondingly more difficult and inaccurate." .This
is incorrect, since we found that this fraction can constitute as much
as 62% of surficial soil. This sampling and separation procedure was
developed with the assistance of soil scientists with doctoral
preparation in this area (8,9). As the guidelines acknowledge, the
hazard presented by plutonium oxide in soils is primarily due to
inhalation. To use other than a respirable surface dust sample will
give misleadingly low values. It is not possible to relate in any
consistent manner the proportion of the respirable fraction to the
surface soil. This is understandable, since the proportion of
windblown material retained at any specific site will depend upon
topography, vegetation, the strength of prevailing winds and many
other factors. The best way to evaluate the hazard is by use of a
surface respirable dust sample, which will provide consistent results
from season to season and site to site. Calculations based on the
questionable assumptions used in this and other sectins have little
value, in my opinion.
Staff Response - The chemical analysis used by Dr. Johnson in
soil sampling was purposely designed to destroy the cementing agents
and grain coatings that bind small particles into microaggregetes,
thereby altering the form in which they actually exist in the
environment. A detailed critique of Dr. Johnson's proposed respirable
size sampling method is contained in Chapter 7 of this document. ,
51. Representative Timothy Wirth , . . ] '
I think that the enhancement factor approach that was used to
correct the "mass loading" assumption will tend to make the results
more valid, but it seems to me that more research needs to be done on
this problem. Not only the "mass loading" approach an equilibrium
approach — which may need to be corrected for nonequilibrium effects
in order to become a more realistic model —but the entire issue of
respirable particulates, and the weight that should be given to them,
must be dealt with better as well. This implies no criticism of the
EPA's effort. I am sure that the model used is tlie best now
available. But I think that the model should be improved upon, and
periodic adjustments in the standards, and site analysis should be
undertaken as those improvements occur. An EPA commitment to
98
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25
undertake those improvements and modifications or guidelines would go
a long way to reassuring the populace around Rocky Flats that the best
possible theories are being used to ensure their safety.
Staff Response - The mass loading approach is an averaging over
many *'non equilibrium" conditions which can occur during the course of
a year. It is recognized also that there are localized disturbances
which would not be reflected in the general mass loading level. The
agency staff has attempted to scope the impact of such localized
disturbances (see Annex II) and concluded that the soil screening
level is sufficiently conservative in these situations.
The Guidance is a recommendation on dose limits for transuranium
elements. The screening levels for air and soil are administrative in
nature and are only for the purpose of identifying areas where
remedial actions may be necessary. Site-specific data should be.
collected and the potential pathways analyzed in order to determine
whether remedial action is requiredi • ••> » •
The agency staff concurs that, if significant new information
should become available in the futurej changes in the Guidance would
be appropriate.
52. Representative Timothy Wirth :
I think that the analysis of the dust problem could be refined by
further research. Is the distribution of radio-active elements in the
dust the same per unit weight as in the top cm. of soil, or are there
differences both in total dose/gra. and in the size distribution of it,
for example. •. , ,
• i : ••.". • .' , -
Staff Response — There should be a difference in the activities
per gram of suspended dust verses the activity per gram of the total
soil. The activity per gram of the airborne dust can either be
enhanced or diminished depending upon the way in which the activity is
distributed in the parent soil. If the activity is primarily
associated with the larger, less resuspendible soil particles, the
activity per gram of the suspended dust would be lower; if the
activity is associated with the smaller soil particles, the
resuspended material would have a higher activity per gram than the
parent-soil'., v - - • • • ••! • -v - . • ••••-.- .-••«. .-i
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3.3 Annex III - The Dose and Risk to Health Due to the Inhalation and
Ingestion of Transuranium Elements
1. Dr. Edward Martell
Organ burdens of fallout plutonium in the general public have
already reached levels of (approximately) 0.5 pCi/kg in lung tissue,
(approximately) 0.7 pCi/kg in the liver, and comparable levels in the
gonads and other organs (Moss and Campbell, 1972). Depending on the
microdistribution of this alpha activity in the gonads and at tumor
sites and on the mechanism of cancer induction, this fallout level of
alpha activity may be contributing substantially to the rising general
incidence of cancer and genetic effects in man. If so, exposure of
large sectors of the general public to 200 times higher levels would
have tragic consequences. Based on present knowledge, the only
responsible recommendation regarding public exposure to insoluble
alpha emitting particles would be that such exposures be restricted to
the practical minimum. That practical minimum is, unfortunately, the
level of fallout plutonium in surface soils.
Staff Response - The data for fallout plutonium in tissue used by
Dr. Martell are taken from LA-4875, Plutonium in Autopsy Tissue. It
was later discovered that a standardization error invalidated most of
these measurements. The 1972-73 data reported by the same group in
WASH-1359, Plutonium and Other Transuranium Elements; Sources.
Environmental Distribution and Biomedical Effects are more reliable
and report somewhat smaller organ burdens. More important, both data
sets have a high degree of measurement errors and considerable
variation between different individuals. As described in Annex 3 of
the Technical Summary, they do not provide a means for estimating
organ burdens with confidence.
The Agency's analyses show that the number of persons likely to
be exposed at the proposed limit is small. Contrary to Dr. Kartell's
statement, it is not anticipated that "large sections of the general
public" will be exposed to limiting dose values. The setting of
Federal guidance at a dose level corresponding to average background
radiation levels disregards the uneven distribution of plutonium in
the environment and the costs required to return nature to a pristine
state.
2. Dr. Edward Martell
In the production of chromosome aberrations the biological
effectiveness of high-LET radiation is independent of dose rate and ig
much greater than that of X-rays and gamma rays (low-LET radiations),
particularly at the low intensities of natural background radiation.
ire
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Upton has pointed out "Under conditions of low-level irradiation most
pertinent to environmental carcinpgenesis, therefore, the oncogenic
potency of high-LET radiations is generally assumed to be relatively
high, i.e., 10 to 20 times that of X and gamma rays" (Upton, 1967).
There is growing evidence that the RBE for somatic mutations induced
by high-LET radiation at the low dose rates applicable to background
radiation are even larger, with RBE values ranging from 35 to 100
(Davis and Bateman, 1963; Neary et al., 1963). This is consistent
with the long term repair of mutations induced by low-LET radiation
and the resistence to such repair for mutations induced by high-LET
interactions (Curtis, 1966).
Staff Response - RBE values were not used to assess cancer risks
in the proposed guides. Rather, the hazards from alpha radiation were
assessed directly from human effects data. For genetic mutations an
RBE of 100 was used. This is consistent with the upper range
considered by Dr. Kartell.
3. Dr. Edward Kartell
Insoluble alpha emitting warm particles (i.e., colloidal thorium
oxide and, uranium metal dust) have been demonstrated to be highly
effective in lung cancer induction in mammals and man (Suckow ejt aJL^,
1961; Heuper et al., 1952). By contrast, inhalation exposure to high
levels of radon and its short-lived daughters was singularly
ineffective in promoting lung tumors in mammals but gave raise to life
shortening and other effects (Morken and Scott s 1966). Such
apparently disparate effects for inhaled alpha emitters are readily
reconciled on the basis of the "warm particle" hypothesis (see below)
which implies a high cancer risk only for insoluble alpha emitting
particles which persist in small volumes of tissue and give rise to
alpha interactions with cell at frequencies which optimize the
multiple mutation process. The results of Morken and Scott suggest
that, at highly elevated levels of natural alpha activity (which is
soluble in body fluids), the critical somatic cells which determine
life span usually receive excessive radiation damage before the
saulti-stage process of lung cancer induction is completed.
Staff Response - The Morken and Scott article referenced by Dr.
Kartell is outdated. Chameaud , et al-. , (J. Chameaud, et al. ,
pp. 411-421 in Experimental Lung Cancer . Springer-Verlag , 1974) showed
that, for rats, at least, nearly pure "2Rn an<|
222
Rn
daughters produced adenomas and carcinomas equally well with and
without uranium ore dust while the uranium ore dust alone was
unsuccessful in inducing either adenomas or carcinomas. The "warm
particles or clusters of particles" of uranium ore dust seesn
singularly unsuccessful in inducing tumors in this test system.
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4. Dr. Edward Kartell
The foregoing considerations indicate that, of the various
sources of ionizing radiation to which man is exposed, internal alpha
eaitters merit special attention with regard to their possible role in
the^etiology of human cancer. The fact that participate alpha
activity in the lung gives rise to cancer, whereas, uniformly
distributed alpha activity associated with elevated levels of radon
results in life shortening with no cancers clearly indicates that the
practice of averaging the organ burden and the radiation dose for
internal alpha emitters is unjustified. It is obvious from these
considerations alone that the incidence of alpha radiation induced
cancer must be highly dependent on its distribution. It also follows
from these considerations that the linear hypothesis of carcinogenic
response to radiation is not applicable to the assessment of cancer
risks from alpha radiation. The mounting evidence which indicates
that insoluble alpha emitting particles which persist in tissue may be
implicated in the etiology of bronchial cancer in cigarette smokers is
briefly reviewed below.
The possibility that the alpha emitting radioisotope polonium-210
aay be involved in the etiology of bronchial cancer in cigarette
smokers was first proposed by Radford and Hunt (1964) and relatively
high concentrations of polonium-210 were found in the bronchial
epithelium of low lobe bifurcations in cigarette smokers (Little et
«!•» 1965). More recently it was found that radioactive lead-210~the
22year halflife grandparent of polonium-210, is highly enriched on
tobacco trichoraes and in the unsoluble smoke particle formed by the
combustion of trichomes in burning cigarettes (Kartell, 1974). The
presence of elevated levels of lead-210 as well as polonium-210 at the
bronchial tumor sites of cigarette smokers has been confirmed (Radford
and Martell, 1977). It has been pointed out that the insoluble
radioactive smoke particles which persist in tissue would be very
effective agents of cancer if the mechanism of alpha radiation induced
cancer proceeds via a multiple mutation process (Kartell, 1975). A
multi-step process of alpha radiation induced cancer, referred to as
the "warm particle" hypothesis, is described briefly below and in
attachment #1 (Martell, 1977).
The hypothesis of alpha radiation induced lung cancer, briefly
described in attachment #1, provides a preliminary consideration of
the sequence of events which may be involved in the induction of
bronchial carcinoma in cigarette smokers. It involves a four stage,
multiple mutation process, as follows:
Stage 1; The slow accumulation of insoluble alpha emitting
particles in damaged bronchial tissue. This process is markedly
influenced by physical and chemical cofactors which damage the
bronchial epithelium and thereby enhance the uptake of particles.
-------
Stage 2: The production of premaligttant cells' by alpha radiation.
induced mutations. Most of the mutations induced by alpha
interactions are either lethal or-have adverse mitotic effect. The
latter are eliminated by selection over successive cell generations.
The premalignant cell is conceived to be a transformed cell with .any
of a variety of and/or combination of structural changes which give i£
a proliferative advantage over normal cells. It is proposed that
premalignant cells have normal mitotic controls and normal mitotic
rates but suryive longer to divide a greater number of times than
normal cells. , -
; "•'-.-••
Stage 3; The selective proliferation of premalignant cells -in.
limited clones. This .process proceeds at a stimulated.nitotic rate9
driven by the relatively high rates of lethal alpha interactions in
the environs of warm alpha emitting particles. This process can be
stimulated by other agents which kill cells and thereby enhance
mitptic activity.
Stage 4; Malignant cell formation by an alpha radiation induced
change in any one of the premalignant cell which results in its loss
of normal mi totic controls. This is the fully malignant stem cell
which undergoes, rapid, uncontrolled proliferation to form a tumor.
The first three stages of the, proposed sequence of events proceed
concurrently. The induction of additional structural changes in .
premalignant cells and in the outgrowth stem cells also is a
continuous process which can explain the wide variety of kayotypes.in
lung tumors, the occurrence of multiple stem cells in some .tumors,
etc. Thus, insoluble alpha emitting warm particles which can
accumulate and persist in damaged bronchial tissue, and perhaps at
other tumor sites as well, provides.a carcinogenic agent capable of •
inducing the cytogenetic changes observed in bronchial carcinomas and
most other malignant human tumors (see Atkins in German-,. 1974).
The warm particle hypothesis indicates a lung tumor incidence
proportional to the duration of smoking in years to the fifth power,
consistent with the best epidemiological evidence (Doll, 1971). The
proposed mechanism als'o involves a mitotic activity dependence term
and thus provides a basis for explaining the surprisingly similar
incidence of common tumors in mice and men (Brues, 1959).
A key point in the warm particle hypothesis, and one apparently
not considered heretofore by radiobiologists, is the critical point of
transition between "warm" and "hot" alpha emitting particles which
depends on the frequency of alpha interactions with cells and the
cellular response. To optimise the multiple mutation process in small
cell populations, the frequency of alpha interactions should not
exceed about"one critical hit per cell per day, the approximate time ;
-------
required for a mitotically stimulated cell to proceed through the
complete mitotic cycle and divide. This transition point is
approximately 0.01 picocuries of alpha activity per particle, the
upper limit for warm particles.
Perhaps the most important implications of the warm particle
hypothesis are that natural alpha activity in its natural form has
negligible carcinogenic risk and that the carcinogenic risk from
insoluble alpha emitting particles that persist in tissue is highly
dependent on the alpha activity per particle, on the microdistribution
of such particles, and on the properties of the target cells.
Staff Response - As noted in the response to the previous
comment, recent experimental tests have failed to show a high
carcinogenic response to warm particles. In the absence of bioeffects
data to support the "warm particle" model, it must be considered
spectulative. Moreover, many aspects of Dr. Kartell's model for lung
cancer induction are based on dated references with little
consideration given to current models of carcinogenesis. In
particular, Knudson (A. G. Knudson, Jr., pp. 45-52 in Origins of Human
Cancer, Cold Spring Harbor Laboratory, 1977), Anderson (D. E.
Anderson, pp. 39-54 in Persons at High Risk of Cancer Academic Press,
1975) and Kersey and Spector (J. H. Kersey and B. D. Spector, pp.
55-67, Ibid) have considered mutational models in the light of genetic
predisposing conditions. Knudson, in particular, concluded that
either 2 or 3 events are necessary to produce a cancer, with 3 event
cancers usually being karyotypically abnormal. Recent reports
indicate that the oat cell carcinoma of the lung, the carcinoma
usually associated with lung irradiation, is karyotypically abnormal,
with marker chromosomes (E. R. Fisher, e_t al., Am. J. Clin. Path. 69:
165-172 (1978).
Moreover, additional work is needed to confirm obervations and
identify sources of 2^Po and 2-*-^Pb before the assumptions of
Martell may advance to the hypothesis stage. Although assumptions
made by Dr. Martell concerning the distribution of Pb^lO and Po2l"
in smoke and smokers may be consistent with the work of Radford and
Martell (1977), they remain only assumptions, and extensive work would
be necessary to prove and expand the preliminary findings. Other
sources of Pb2^ and Po2^ must be investigated in addition to
smoking. Many of the sources that may contribute have already been
identified by Moore, Martell, and Poet (1976). For example, short
term inhalation of dust while raking and bagging leaves might lead to
deposition of particles with Po210/Pb210 ratios of O.4.,
equivalent to ratios seen in "smokers".
While Dr. Martell's model is interesting and bears watching, it
is not quantitative and is likely to undergo extensive modification as
it evolves into a less speculative model of cancer risk. It
definitely cannot be used in standard setting in its present form.
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5- Prv Edward Martell
The proposed EPA guidance is based on the assumption "that the
risk at any given low dose level is directly proportional to the
damage actually observed at much higher dose levels." Such an
assumption is particularly inapplicable to internal alpha emitters and
can lead to an underestimation of the cancer risks for insoluble alpha
emitters by factors of hundreds to thousands or more, for reasons
briefly considered here.
Many of the important limitations of the linear hypothesis were
reviewed by Brues (1958, 1959). With reference to multiple mutation
mechanisms like that proposed by Armitage and Doll (1957) which is
reconciled with the age-incidence of cancer in man, Brues (1958)
comments, "This, if applied to radiation, would imply an exceptional
effectiveness of widely spaced dosages, which does not appear to have
been observed." I must comment that one cannot observe what one does
not look for. -It is^proposed that insoluble "warm" alpha emitting
particles which persist at tumor sites, give rise to malignancy via a
multiple mutation process (attachment #1). Insoluble warm particles
which accumulate and persist at human tumor sites appear to me to be,
the exceptionally effective radioactive carcinogens that Brues and
others have overlooked. As noted above, warm particles may be
expected to give rise to cancer risks several orders of magnitude
higher than that for the same alpha dose from hot particles, and the
risks attributable to natural alpha emitters which are soluble in
tissue are neligible. Thus, the warm particle hypothesis is
completely at odds with the linear hypothesis and indicates that the
carcinogenic response is highly dependent on the spatial distribution
of the alpha activity and the alpha activity per particle (or,
alternatively, on the frequency of alpha interactions with the target
cells). The warm particle hypothesis and other possible multiple
mutation models can be tested experimentally. It is very important
that we,do so.
The results of Morken and Scott (1966) discussed above (comment
3) also are at odds with the linear hypothesis but are readily
reconciled with the warm particle hypothesis. These results imply
that, to be most effective for tumor induction rather than
life-shortening, elevated levels of alpha radiation should be
restricted to a small tissue volume in the organs at risk. On this
basis, small populations of insoluble alpha emitting particles which
persist in small volumes of tissue sites would appear to have
exceptional carcinogenic potential.
The practice of averaging alpha activity burdens and doses for
each organ, usually necessitated by lack of adequate information on
the microdistribution, has futher compounded the confusion with regard
to the biological end effects. The average alpha radiation dose for
-------
an organ or tissue volume, in which many of the cells are not
irradiated at all and others are killed by an excessive number of
alpha interactions, is a completely unreliable index of effects. Even
when the high-LET irradiation pattern is known, the biological effects
are still not a simple function of dose adjusted by an arbitrary
quality factor, as Katz and Sharma (1974), Brustad (1961) and others
have pointed out.
On the basis of the foregoing considerations, the basis of risk
estimates for the proposed guidance is hopelessly inadequate and, for
a multiple mutation process of cancer induction, grossly
underestimates the risks for alpha emitting warm particles.
Staff Response - Dr. Kartell's contention that the linear
hypothesis underestimates risk by orders of magnitude is not supported
in this argument nor by animal data. Experiments by Chameaud e_t al^,
(j. Chameaud, e£ al., pp. 411-421 in Experimental Lung Cancer,
Springer-Verlag, 1974) show that, in rats, even filtered radon-222 (an
almost pure diffuse alpha dose) can cause lung cancer and the more
homogeneous the dose the greater the risk (j. Lafuma, et al., pp.
43-53 in Radiation Protection in Mining and Milling of Uranium and
Thorium, ILO Geneva, 1976).Similar results have been obtained in
Syrian Hamsters by Anderson, e_t al. They found localized irradiation
both alpha and beta, is less tumorogenic than diffuse exposure (E. C.
Anderson, et al., pp. 10-14 in LA-6898-PR, 1977). These animal data
are contradictory to Dr. Kartell's suggestion that the risk is
underestimated because of special spatial dose considerations for
"warm particles.":
The argument that the use of the 1972 BEIR report risk estimates
is an underestimate of the risk by orders magnitude is not supported.
6. Dr. Edward Kartell
Reports of the Advisory Committee on the Biological Effects of
Ionizing Radiation (National Academy of Sciences, 1972 and 1976) have
a number of serious shortcomings with respect to the assessment of the
distribution of internal alpha emitters and their genetic and somatic
health effects as follows:
a. Internal dose: The contribution of inhaled and ingested
alpha emitters from natural and pollutant sources to the internal
radiation dose at most critical soft tissue sites in mammals,
including man, have not been determined. The limited published data
on the distrubution of polonium-210 and radium-226 indicate wide
variations in their concentrations from organ to organ and within each
organ. What is the dose contribution at various soft tissue sites for
ire
-------
8 • •• . '
the 11 natural alpha emitters: thorium-228, radium-224, radon-220,
polonium-216, bismuth 212, polonium-212, radium-226, radon-222,
polonium-218, polonium-214, polonium-210? These radioisotopes are
present in some industrial plumes (Poet and Kartell, 1977) and inside
buildings, depending on construction materials and other factors. The
added contributions of particulate alpha emitters from industrial and
fallout sources (polonium-210, uranium and thorium compounds,
plutonium-239 and americium-241) and their microdistribution ii
organs merit particular attention.
microdistribution in mammal
b. Genetic effects: Contributions of internal alpha emitters to
the spontaneous mutations rate and to the genetically significant
radiation dose have not been determined. Because of the exceptional
effectiveness of alpha emitters in the production of chromosome
aberrations, it is essential to assess their concentrations at the
germ cell sites. Relatively high concentrations of polonium-210 have
been found in the sperm of cigarette smokers (Hunt, 1973) and Green
et al., (1975) reported higher concentrations of plutonium near the
sperm sites than elsewhere in the tests. The presence of insoluble
alpha emitting particles at the germ cell sites is a disturbing
possibility that must be investigated experimentally.
c. Cancer risks: The microdistribution and micro-dose
distribution for insoluble alpha emitting particles at human tumor
sites, and the cancer risks attributable to such particles on the
basis of multiple mutation processes, have not been assessed by the
BEIR Committee. The possible role of alpha emitting "warm particles"
in the etiology of bronchial cancer in smokers is discussed briefly in
attachment #1 (Martell, 1977). Because alpha emitters are
exceptionally effective agents for the production of the gross
chromosome aberrations that are present in most human tumors (German,
1974), the possible presence of warm particles at other common tumor
xsites also should be investigated.
d. Atherosclerosis: Insoluble alpha emitting particles may be
implicated in atherogenesis (Elkeles, 1977; Martell, 1975). This
important possibility merits serious attention by the BEIR Committee
and the National Institutes of Health.
Staff Response - The extent to which the NAS-BEIR Committee may
incorporate Dr. Kartell's suggestions into their current updating of
their 1972 Report is unknown. His views were presented to the
Committee at his request in July 1976. In the past the Committee has
based its risk estimates on observed effects occurring to persons in
irradiated groups. The Agency agrees that the role of alpha-emitting
particulates is an important public health question and that the
microdosimetry of these materials is essential to an understanding of
-------
their potential impact. Where data is available on this point, it was
incorporated into the Agency's estimates of the risk from transuranium
radionuclides.
The question of the contribution of "warm particles" to hazards
in solid organs must be deferred until such particles have been
indentified in organs and in areas of interest.
The relationship of atherosclerosis and "warm particles" is at
best very tenuous. The co-deposition of calcium and alkaline earth
elements is well documented. Calcification in fat and calcification
in necrotic and injured cells in the body is also well documented.
The finding of deposited alpha emitters in atherosclerotic lesions may
not be significant. The "warm particles" certainly do not fit easily
into the picture of atherosclerosis pathology developed by French
(J. E. French, Intern. Rev. Exper. Pathol. 5^253-353 (1969).
7. Dr. Edward Kartell
The foregoing discussion indicates that the proposed guidance is
based on hopelessly inadequate information on the internal
distribution of alpha emitters and their genetic and somatic effects.
Additionally, the assumptions and models used as the basis of risk
assessment are highly questionable and may lead to very substantial
underestimation of cancer risks and genetic effects.
Consequences of public exposure to transuranium elements in the
environment are extremely serious questions which should be addressed
by the most knowledgeable and objective scientists in the field of
radiation health effects. It is far from clear that the unidentified
scientists who generated the proposed guidance have such credentials.
The quality and content of the guidance report suggest otherwise.
Based on present state of knowledge of the genetic and somatic
health effects of insoluble alpha emitting particles, public exposure
to such particles must be restricted to the practical minimum—several
times fallout or less."
Staff Response - Dr. Kartell's conclusion that the proposed
guidance is based on "hopelessly inadequate information" is somewhat
overstated. The Agency uses dose models developed by an international
commission of radiation protection experts. Similarly, analyses of
radiogenic lung cancer developed by the National Academy of Sciences
and derived from exposure of humans to radiation are used to estimate
risk. The question is not whether the Agency's scientists are
knowledgeable or objective, but whether they could responsibly
disregard this information, developed by a large group of scientists,
on the basis of the untested model of carcinogenesis proposed by the
commentor.
ire
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10
Where possible, the guidance is based on epidemiological
information on the hazard from alpha emitting radioelements. The risk
estimates used are tempered with information from animal studies and
from other human exposures. While there is uncertainty in the risk
estimates, it is not orders of magnitude and probably is less than a
factor of 5.
8. National Council on Radiation Protection
The factors for the uptake from the GI tract in Annex III are of
considerable importance because they are orders of magnitude higher
than have been used. However, there is practically no justification .
for them nor is the estimated degree of conservatism indicated.
Staff Response - The basis for the selection of these factors is
given in Section 6 and in Technical Note CSD-78-1 (selected topics:
Transuranium Elements in the General Environment, Office of Radiation
Programs, EPA, 1978).
9. Colorado Environmental Health Association
As for the guidance itself, Johnson (1977) in a paper presented
to the Annual American Public Health Association has reported
increased leukemia death rates in the eight census tracts nearest -
Rocky Flats as compared to nineteen census tracts located in southern
Jefferson County. These death rates range>from 2 to 3 times the rates
from southern Jefferson County. The census tracts nearest Rocky Flats
range from 3 to 33 mCi/km2 .or 0.003 to 0.033 uCi/m2 in plutonium
contamination of the soil. The. proposed guideline of 0.2 uCi/m2 is
from. 6 to 66 times the level associated with increased leukemia rates
according to the study.
Staff Response - Dr. Johnson's 1977 report on a possible
association between plutonium contamination and the annual rate of 4
leukemia deaths around Rocky Flats and 1 leukemia death in Golden
County (as compared to 2 leukemia deaths in southern Jefferson County)
is premature. As Dr. Johnson points out, local (cancer mortality)
rates vary widely.
J. Sutherland (Director of the Cancer Patient Data System,
Regional Cancer Center, Denver) pointed out in his June2, 1978, memo
to the Rocky Flats Monitoring Committee: "Because of the small numbers
of cases involved, it is important that another control area be
identified to compare to the Rocky Flats area. It would not be
surprising to find a random fluctuation of 2 cases of leukemia in
various areas of Colorado. For example, the number of thyroid cancer
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11
deaths in Colorado fluctuates from one to eight cases per year during
the period 1960-1976 with no discernible trend. The eight cases in
1968 are much different than the two cases in 1969, but this
difference is meaningless."
Sutherland also pointed out possible problems in accuracy of
diagnosis available from death certificates, mobility of the
population and the need for examining the incidence pattern over an
extended time period. He concluded: "The results reported by Dr.
Johnson are preliminary and of a suggestive nature only, and provide
no conclusive evidence of anything due to small numbers of observed
cases over a single year using death certificates. I feel that Dr.
Johnson has stated this in his presentations, but perhaps not
forcefully enough."
Indeed, Dr. S. W. Ferguson (Chief, Chronic Disease, Colorado
Department of Health, Denver) pointed out in his February 23, 1978,
letter to Dr. Carl Johnson (Director of the Jefferson County Health
Department) that the Rocky Flats and control areas examined by Dr.
Johnson each have a lower combined lung and leukemia incidence rate
than was observed in two other control areas, one in Jefferson County
and one in Arapahoe County. Dr. Ferguson also pointed out that
population growth rates in the census tracts examined may play an
important part in interpretation of the cancer rates.
Before an association of plutonium contamination and leukemia can
be inferred, data must be available for a number of years to average
out the normal large fluctuations in annual death rate seen in small
populations. Duration and comparability of residence times in the
area must be established, comparability of populations for
occupational and environmental exposure to known carcinogens, current
and prior exposure, age, and sex distribution, etc., must also be
estimated. Dr. Johnson has yet to adjust for these variables.
10. Department of Defense
Basic Guidance: The proposed guidance of 1 mrad per year to the
lung and 3 mrad per year to the bone are considered to be overly
restrictive, possibly by a factor of 100. If this is true, screening
levels and permissible annual dose rates should be increased
accordingly. Explanations follow:
The Summary Report gives risk estimates derived from an EPA Life
Table Methodology. An illustration of results using the EPA
Methodology and NAS-BEIR data is given in Annex 4, pg. 9 of the
Summary Report. Background radiation (100 mrem per yr) is indicated
to cause 144 premature deaths per cohort-lifetime. (The single value
is determined as an arithmetic mean of geometic mean relative risk and
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geometric mean absolute risk, where the geometric means, are of two
"plateau" values. This averaging method is presumably the one
followed by EPA elsewhere in the Summary.Report). Since lifetime is
71 years the EPA Methodology yields 2 deaths per cohort-year due to .
background radiation. The NAS-BEIR Report (pg. 169) yields 3614
"excess deaths" per US-Population-Year due to background radiation.
(This value is determined also as the arithmetic mean of geometric
means of data given at pg. 169), This value can be expressed in
similar units to those used by EPA—assuming 200 million persons as,US
Population, and 100 thousand persons in a cohort, the NAS-BEIR risk
methodology gives 1.8 extra, premature deaths per cohort-year. Thus,
the two risk methodologies yield equivalent results when evaluating
background-radiation impact.
The NAS-BEIR Report shows (pg. 171) absolute risk of lung cancer
as 1.3 per million-person-year-rem. (Similar values are given
elsewhere in the Report; e.g., "beat" risk estimates range from 0.07
to 1.6 on pg. 151, and the average for adults only is given as 1.0 on
pg. 150. These estimates are primarily on case studies of persons
chronically exposed to radiation). The NAS-BEIR input data is given ,
in rad units, and conversion to rems is made in the Report by using an
RBE of 10. Absolute risk of lung cancer according to NAS-BEIR then,is
13 deaths per million-person-year-irad, or 0,013 per million-person-
year-mrad. -,., .
The EPA Rationale for Guidance states "The risk at the proposed
guidance level is estimated to less than one chance in a million.per
year...". , As used in this instance, "less than one" means "in the
order of one" since the value is obtained by dividing the risk per
cohort-lifetime (10 deaths) by 71 years. Since the proposed lung
guidance.level is 1 mrad per year, the EPA Methodology gives a risk of
1.4 deaths per million-person-year-mrad, in contrast to 0>013 deaths
per million-person-year-mrad estimates by NAS-BEIR Methodology.
Since the EPA and NAS-BEIR methodologies give equivalent results
for estimates of background radiation effects, one would not expect
estimates to differ by a factor of 100 for the case of lung radiation
effects. The,reason for this discrepancy is not apparent in the
background material provided. Perhaps the real answer will be
apparent when EPA "in-preparation publications" (References 1, 6 and
9, Annex III and 5, IV) are made available for review. If not, then .
EPA should provide an explanation for the apparent difference.
The Summary Report makes the case that a risk of "one in a
million" is suitable for transuranics in the environment because it is,
comparable to risks used for other carcinogens. If the NAS-BEIR risk
estimates are correct, the EPA estimates are in error and the risk of ,
one-in-a-million is.to be maintained, then the proposed guidance must
be stated as 100 mrad per year to the pulmonary lung, not 1 mrad per
year. Bone dose and screening levels also must be increased.
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Staff Response - This comment is based on an erroneous
interpretation of the information on absolute risk given on page 171
of the 1972 NAS-BEIR Report. The absolute risk for lung cancer is
listed as "1.3/106/year/rem." This risk coefficient in the 1972
BEIR Report means that the probability that an individual will die of
excess lung cancer following a one rem dose is 1.3 x 10~6 for each
person year at risk. It is not the risk for a given dose rate (rem
per year). This interpretation can be verified by calculating the
absolute risks tabulated for total cancers on page 173.
Because an individual averages about 35 person years of risk for
each annual dose increment received over a lifetime (lifetime
plateau), the lifetime risk is about 35 times larger than assumed by
the commentor. Moreover, averaging relative and absolute risks and
considering the increased effect of childhood exposure increases the
risk estimates by an additional factor of about 3. The neglect of
these factors by Department of Defense has the overall effect of their
underestimating the risk by a factor of more than one hundred.
11. Colorado Department of Health
The Department has been allowed to review and comment on several
of the earlier drafts. Each time we have requested simplified
equations to inform the reader as to the relationships between the
risk, the biological risk estimator, the dose or dose rate commitment,
the air concentration and the soil concentration. While the entire
document does address these matters, nowhere is the relationhip
summarized to place the entire process in prospective. Additionally,
we have also commented that all of the equations be provided in
detail. The "Plutonium Air Inhalation Dose (PAID)", Technical Note
ORP/CSD-77-4, document was an attempt to provide the dose calculation
procedures used by EPA in the development of the guidance. While our
review of this publication is currently incomplete, there are some
rather important defects involved. Figure 1, page 5, has improperly
depicted pathways (d) and (g). Appendix I does not identify the terms
used in the derived equations to allow another agency to use it with
relative ease. The equations as provided are incomplete, as there are
summations that must be done for each equation. Appropriate notation
is necessary if the equations are to be correct. Appendix II does
provide an example; however, the values used are not easily
discernible. With the provision of the term identification in
Appendix I and the values in Appendix II, calculation to confirm the
EPA process would be properly provided for. It must be pointed out
that the EPA and this Department's chronic exposure dose rate
calculation procedures produce results not significantly different for
the same parameters.
Staff Response - The misprint in Figure 1 of the PAID document
was inserted when this figure was drawn. The equations and computer
• •? O
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14
code are not affected by this error. The;equations in the PAID
Appendix I are complete in that they are valid for any organ or lung
compartment in a chain. While they must be summed to obtain total
dose/dose rate, the summation process is described in the main text*
While the request for a simplified set of equations is understandable,
it is not likely that any such set would cover the range of cases
considered in the guidance document. The computer code is available
on request from EPA. ,
12. Colorado Department of Health
Annex III of the guidance document provides data on various
aerosol particle size distributions and resultant doses, etc. The
ICRP in adopting the TGLM Clearance Model used only a 1 urn AMAD
aerosol particle size distribution. The pathway parameters
recommended by the ICRP are based on that particle size for deposition
in the various compartments of the respiratory tract and translocation
to the blood and gastro-intestinal tract. The use of particle sizes
considerably smaller than 1 urn AMAD for Class Y compounds will result
in an underestimate of the health risk due to the greater effective
solubility of the smaller particles. The document references particle
size distributions down to 0.01 urn AMAD; however, the tables in Annex
III do not include that particle size. .
Staff Response - The question in not clear. While,the ICRP
recommended that, for unknown aerosol size distributions, a 1 urn AMAD
be used in the ICRP model-, the ICRP Task Group Model is applicable to:,
a wide range of particle size distributions (Figures 13 and 14 of Ref.
5). One limitation of the model is that solubility is a function of,
the compound class and is not related to particle size. The guidance
document was based on particle sizes from 0.05 urn to 5.0 urn. Typical
results for this range of sizes are given in Annex III. This size
range encompasses most aerosol distributions (Ref. 5, p. 183).
Aerosols consisting of smaller particles are.outside the range of
validity of the ICRP model (Ref. 5, p. 185) and, in any event,, are
expected to result in decreased, not increased, pulmonary deposition •
(Ref. 5, p. 185).
The question of increased solubility has been considered by EPA.
Some typical results for Class W compounds.are given in Section 6.
13. Conference of Radiation Control Program Directors
The method of calculating, dose must be more explicit so that the
entire procedure can be duplicated by those interested. -,. It should
also be pointed out in the document that fresh soil contamination may
be a Class W compound which would provide a greater hazard to the
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bone. The basic guidance should be the primary controlling factor.
In some circumstances reliance on the Class Y data and the associated
soil screening value will not provide adequate protection.
Staff Response - The method used in calculating doses is
relatively standard in that it follows the ICRP TGLD-lung model and,
for the most part, uses ICRP metabolic parameters for the reference
organs. Estimates of the hazard of Class W compounds can be found in
Section 6. ,, .
The "soil screening" level is specifically designed to address
only those cases where inhalation is the primary pathway to man. In
most cases of environmental contamination, the suggested screening
level of 0.2 uCi/rsr- leads to pulmonary lung and/or bone dose rates
well below the Guidance recommendations. The lung dose rate is
generally governing because newly deposited transuranium element
contamination, which may consist of very fine particles, is relatively
insoluble. The more weathered and soluble particles are expected to
have a larger activity median aerodynamic diameter (AMAD).
Section 6.3.2 in this volume describes the application of the proposed
guidance to Class W transuranium compounds. In a few cases where
alternative pathways, such as ingestion, comprise a significant part
of the total exposure, these must be considered on a site-specific
basis.
14. National Resource Defense Council
EPA underestimated the somatic and genetic effects of low
dose/low dose rate irradiation.
Staff Response - Somatic Effects - The Agency notes that risk to
health due to transuranium elements in the environment is almost
entirely due to high LET (alpha particle) irradiation and that the
Agency's risk estimates are based only on the potential effects of
alpha irradiation. With the exception of Dr. K. Z. Morgan's paper,
the references on somatic risk cited by the NRDC discuss the effects
of low LET radiations. While the Agency agrees there is considerable
controversy concerning the effects of low LET radiations, none of the
new studies cited by the NRDC provide information on the risks due to
chronic exposure from internally deposited alpha particle emitters.
Dr. Morgan's discussion of the inhalation hazard due to plutonium is
based on acute effects from massive doses, (kilorem) not cancer risk.
The baboon studies he cited are not relevant at the low doses where
delayed cancer, not acute health effects, are the potential public
health problem.
The Agency agrees with the 1972 NAS-BEIR Committee that the
linear hypothesis may either overestimate or underestimate the risks
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due to-low'levels of ionizing radiation (EPA-520/9-73-003-D); "
However, as stated in Annex III, the Agency believes appreciable
departures from a linear response are less likely for high LET than
low LET radiations. Nevertheless, the Agency recognizes that all
current risk estimates are of necessity based on incomplete data. '.
Because of the uncertainty in radiation risk estimates, the Agency
contracted with the National Academy of Sciences in 1976 to constitute
a new BEIR Committee to reevaluate the potential health risk due to
both high LET and low LET radiations. This Committee is reviewing the
most recent radiation health effects information, including that on
alpha particles, in order to determine to what extent the 1972
NAS-BEIR Committee risk estimates used in the preparation of these
Guides may be changed. The Agency will consider the need for
modification of its risk assessment upon completion of the NAS study
in 1978.
Staff Response continued - Genetic effects - The >NRDC cites two
studies to support its view that the estimate of genetic- risk is too
low. The first by Dr. M. F. Lyon calls attention to a possible
increase in genetic risk at very 'low-dose -rates over that calculated
by the BEIR Committee in 1972. The EPA risk estimates are for alpha
particle emitters.-and therefore do not assume fewer effects at
low-dose rates. As explained in Annex III, the Agency's estimates of
the genetic risk is five times greater than that of the 1972 BEIR
Committee. The other study cited by the NRDC is the report by B. K.
Trimble and J. H. Doughty on the frequency of genetic disorders found
in British Columbia. The reported frequency in British Columbia, of
disorders having a complex etiology, which includes a genetic
component, is a factor of two greater than that li'stefd in the 1972
NAS-BEIR report; 90 per 1000 live births as compared to 45 per 1000.
The important question however is the degree to which these diseases
have a mutational component,' i. e., are transmitted to future
generations. The 1972 NAS-BEIR Committee estimates their mutational
component as between 5 and 50 percent and the Agency's genetic risk
estimates in Annex III are based on this range of possible values.
Recently," (1977) UNSCEAR has estimated ten percent as an upper limit
for this mutational component. Therefore, the Agency believes its
estimate of genetic risks is conservative and that the range of
genetic risks presented in Annex III encompasses the factor of two
reported in British Columbia study. The Agency notes1 that until his '
recent death,-Dr. Trimble was a member of the NAS-BEIR Committee
reevaluating their 1972 report and that his studies will be considered
in preparing the Academy's new estimates of genetic risk to be
published this year.
15. Natural Resources Defense Council
By using an incorrect relative damage factor for bone, EPA
underestimated the radiotoxicity of plutonium in bone.
5
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17
Staff Response - The relative damage factor "n" had been used by
ICRP Committee 2 to relate the risk of bone cancer due from radium-226
uniformly deposited in bone to the dose and risk from plutonium and
other radionuclides which deposite on bone surface and thereby
irradiated a larger proportion of cells at risk for cancer induction.
Since in both cases the dose was calculated by averaging the emitted
energy throughout the skeletal mass, the n factor corrected for the
uneven deposition of energy by bone surface seekers. It should be
noted that the ICRP has recently (1977) defined dose-to-bone in terms
of the dose-to-bone surfaces and defined a quantity N "the product of
all other modifying factors", (except the quality factor, Q) as
unity. In view of the context of the NRDC comment, it is assumed here
that the NRDC comments refer to n, "the relative damage factor for
bone", and not the quantity N.
In its review of the data of radiogenesis of bone cancer, the
Agency carefully considered the precedents established by the ICRP,
K. Z. Morgan, and others in relating estimates of risk due to
radium-226 to other alpha emitters. However, the Agency staff
concluded that such an approach was too indirect because of the
dosimetric difference between the results of radium-226 and plutonium
deposition and, instead, used a more direct approach based on
epidemiological studies of persons chronically irradiated with
radium-224 which, as explained in Annex III, irradiates only bone
surfaces. These data were not available when the n factor concept was
developed by the ICRP. Contrary to the NRDC comment, no N or n factor
has-been implied by the Agency in its evaluation of the risk of
radiogenic bone cancer. Rather, the risk estimate is the result of a
straightforward application of the most relevant biological data on
the results of human exposures.
16. Natural Resources Defense Council
EPA did not consider the harzard of hot particles in the
induction of lung cancer.
Staff Response- The Agency agrees with the National Academy of
Sciences' study that concluded that, if there is a hot particle risk,
it is small by comparison with lung cancer risk attributable to the
generalized alpha radiation (NAS-76). As pointed out in Annex III,
the Agency's estimates of the risk of lung cancer are conservative in
that it is based on the dose to that portion of the Agency receiving
the highest average dose, the pulmonary region, notwithstanding the
fact that most radiogenic lung cancers in humans are found in the
bronchial region where the dose at the proposed limits is a factor of
more than ten smaller, Table 3-2, Annex III. The Agency's position on
the hot particle hypothesis and the NRDC petition to use this
hypothesis as the basis for Agency estimate of risk due to the
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18
inhalation of plutonium was published in 1977, 42 FR 1288. While the
Agency has ,been aware of the NRDC's dissatisfaction with the National
Academy's analysis of the hot particle hypothesis, it does not believe
that a recapitulation of this issue is necessary to insure that the
estimates of lung cancer risk used in the preparation of these Guides
are adequately conservative. *
17. Nuclear Safety Associates
In a technical point, the dose-risk relation for inhaled transu-
ranics was based on the product of an annual average dose rate to
pulmonary lung tissue of one millirad per year and the unit risk
appropriate,for bronchial cancers (i.e., in bronchial tissue). The
dose and the risk estimates were not to the same tissue. The dose to
pulmonary tissue was calculated by the EPA to be about 20 times higher
than the tracheobronchial dose. However, in Hiroshima survivors, the
significant increases in lung cancer occurred in the bronchi rather
than in the pulmonary region. In short, a lung dose, rate limit based
on the product of the region receiving the highest dose and the risk
to a different region which has the highest risk per unit dose would
not be realistic and would not provide protection corresponding to the
intended maximium level of risk. Instead, a lung dose rate limit set
on this basis would appear to be much more restrictive than intended.
Staff Response - This information was included in Annex III and.
the point made is :recognized by the Agency. See the reply to comment
16. , . -
18. Jefferson County Health Department
...I believe that the estimated risk is understated.. .much more
than a "sma,il fraction" of plutonium retained in the lung is
translocated to the bone. (The Guide should be reduced because of the
factor of 3 uncertainty in Annex III). (Page 60948 - F.R.)
Staff Response - The Agency agrees that characterizing this
fraction as small is incorrect. In accordance with the ICRP task
group lung model, the risk estimates in Annex III are based on the
assumption that about 20 percent of the material initially deposited
in the lung is translocated to other organs. However, the Agency does
npt agree that ,the degree of uncertainty in the estimated risks are a
reasonable basis for.reducing the proposed Guides since the degree of
uncertainty in the risk estimates, as well as the conservative nature
of the exposure situationg, (e.g., lifetime residency, and the .
conservatism in the risk modeling) were considered in the development
of these Guides. !
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19. Jefferson County Health Department
The dose limits are higher than those promulgated by EPA for
drinking water. "
Staff Response - The comment seems to imply that the maximum
contaminant limits for radioactivity in drinking water replace Federal
Radiation Protection Guides for exposures to the general population.
They do not; the drinking water regulations are specific on this point
(41 ER. 28409). The drinking water limits are for a single pathway,
finished drinking water. The proposed Guides for transuranium
elements in the environment include the doses due to inhalation and
food pathways and are limited to contamination by transuranium
elements.
The proposed guides provide for a 3 mrad annual dose limit for
bone tissue after lifetime exposure. The drinking water regulations
limit the annual dose rate to bone tissue due to alpha particles from
radium-226 to 15 mrad per year (EPA-570/9-76-003, National Interim
Primary Drinking Water Regulations).
20. Jefferson County Health Department
In addition to resuspension of plutonium from surface dust, we
must also consider the release of particulate to plutonium from
plutonium-processing plants. These particles are for the most less
than five microns (micrometers) in size and large numbers are released
at times. Eight days after a fire at Rocky Flats in 1957, as many as
125 million of such five micron particles of their equivalent were
released in a single day from a stack (3). A two micron particle of
plutonium oxide, if inhaled, would produce a dosage of over two
millirem to the lung, 96 millirem,to the tracheobronchial lymph nodes,
and^six millirem to bone (4). A particle five microns in size could
be inhaled and retained and produce a dose tq about 40 millirem to the
lung, 1,700 millirem to the tracheobronchial lymph nodes, over 130
millirem to the bone, ,,50 millirem to the liver, . eight millirem to the
kidney, and two millirem to the gonads, where a'pattern of
microdeposition of plutonium would give a proportionately greater
effect than would be expected. Particles of this size, of course, are
microscopic in size and of the same order of size as bacteria, and may
be blown^by, the wind for great distances. A single particle only two :
microns in size, if inhaled and retained, will produce a dosage
exceeding the EPA 4 millirem maximum annual dose (4)..
Staff Response - The Guidance does not appjly to routine,
controlled emissions. The dose estimates used by Dr. Johnson are
taken from a 1974 paper by Dr. N. Barr. Dr. Barr presented his
estimates for 0.3 urn AMAD (0.1 urn Diameter) particle's as either Class
Y or Class W compounds. Dr. Johnson has combined the estimates for
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Class Y and Class W, an impermissible aggregation, .and then used these
dose estimates for a 5 urn (actual, diameter) particle. Thus, his
soluble/insoluble particles overestimate dose by a "factor of about 4
due to change in particle diameter. Moreover, in his analysis they
are assumed to continue to irradiate lung and lymph nodes even after
they dissolve and are deposited in the rest of the body. The
reference to the 4 mrem maximum contaminant limit for drinking water
is inappropriate. See response to comment 19.
21. Jefferson County Health Department
The proposed guidelines state that persons with a continuous
exposure to one millirad of plutonium-239 would have less than one
chance per million per year and less than 100 chances per million in a
lifetime of dying of cancer. One millirad of plutonium-239 is
equivalent of 20 millirem in lung, with correspondingly larger values
in other organs. I estimate that there will be a total increase of
all cancers of perhaps 0.06 to 0.2% over a period of seventy years due
to this exposure, or 600 to 2,000 excess deaths from cancer per
million persons (4). In addition, there will be an increase in the
incidence of all genetic dieases by 0.1%, and ill health related to
chromosome mutation by 0.6% for all succeeding generations. I think
that in making such estimates that it is risky to rule out
potentiating factors such as the effect of smoking on asbestos workers
and uranium miners. Such potentiating effects may be expected.
Staff Response - The author of the comment appears to have
misinterpreted the 1972 NAS-BEIR Report. The BEIR Report increase in
cancer was calculated on the basis of chronic-unifbrm total body
irradiation and reflected an increased incidence in cancer mortality,
not an increased incidence of mortality due to all causes. A 1%
increase in cancer mortality is about a 0.2% increase in mortality
from all causes. Therefore, the commentor's results are five times
greater than a correct evaluation.
' In addition, developing risk estimates for individual organs
requires development of risk estimates similar to those in BEIR Tables
3-3 and 3-4 for each organ. The BEIR Report risk estimates for total
body dose cannot be applied. Mor'eover, even if such an approach were
taken, the risk estimates would be too high by a factor of 2 or more
since the dose to lung is equilibrium before other organ doses for
Class Y compounds. This factor was neglected also. '
In either case his calculation of .mortality is wrong. The
increase in the BEIR Report is given as a percent increase in cancer
mortality, not total mortality. Assuming an increase of 0.06% to 0.2%
in the total cancer mortality, yields, per million persons at risk, an
additional 108 to 360 cancer deaths, not the 600 to 2000 calculated by
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Dr. Johnson. Further adjustments for differences in dose rates and
total doses for specific organs would yield estimated excess cancer
mortality close to that developed by the Agency in Appendix III of the
proposed guides.
A similar situation holds for Johnson's estimates of genetic
risk. If the BEIR Report genetic risk estimates are used, the 0.1%
increase in incidence of genetic diseases and 0.6% in ill health
calculated by Dr. Johnson imply each parent received an average of one
rem gonadal dose between birth and age 30. The gonadal dose estimated
by Dr. Johnson appears to be 2 thousandths of a rem or less per
person. The genetic risk, thus, appears to be overstated by a factor
of 500 or more.
The commentor's final comment, that potentiators such as smoking
should not be discounted, is valid. Since lung risk estimates are
derived primarily from uranium miners studies and the uranium miners
smoke about as much as U.S. males of the same age, the synergism of
smoking is already included in the risk estimate. The effects .of any
unidentified potentiators are also included in the risk estimates to
the extent that the exposure of uranium miners is equivalent to that
of the U.S. population. In the absence of any other data no further
adjustment of risk estimates can be made.
22. Jefferson County Health Department
In any discussion of dose limits for plutonium or other
transuranium elements, new evidence relative to the adequacy,of such
dose limits must be considered. A recent report of a study of
plutonium workers at Rocky Flats found a significant increase in
chromsome abnormalities in the blood lymphocytes of plutonium workers
who had received only 1% to 10% of the body burden of plutonium
permitted by the present federal guidelines (5). This is very
significant, because it indicates that the present guidelines are
inadequate and are not providing protection for plutonium workers.
Existing federal guidelines to provide radiation protection from
plutonium should be decreased by at least a factor of 100 in order to
achieve a level where no observable effects are noted. A reduction in
the maximum permissible level of plutonium for workers should result
in a corresponding reduction in the radiation protection guides for
the general public. Recent reports by Dr. Karl Morgan and Dr. Myers
also suggest that the present Federal guidelines are too high by a
factor of about 200 or more (6,7).
Staff Response - The Agency is familiar with Dr. Brandom's work
on peripheral lymphocyte cytogenetics, and at present agrees with Dr.
Brandom's position of not drawing any hereditary or clinical
implications from the data. Chromosome aberrations have been observed
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after many types of physical or chemical insults, but as yet,, there is
. o
which will, as necessary, be incorporated into Federal guidance.
However, it should be noted that the lowest bone marrow doses to
which these industrial workers are being exposed and where these
effects are seen is about 50 times greater than would occur at the
proposed guides.
The Agency ha,
,
m» properly compared, as done in the referenced paper, the Agency s
toS .rSHrttaate differed from Dr. Morgan's estimate by a factor of
3 or less. . . ,
23. Jefferson County Health Department.
The report notes that "unlike radium-226, which is distributed
throughout Pth^ bone volume following Aong-term -gest^,. plj™ »
nrpferentially deposited and retained near bone surfaces . As mucn as
§5% to ?0% of Plutonium has been shown to be retained on osteogenic
cells! Americium and curium are also retained on bone surfaces and
so, more prone to be a cause of radiogenic bone carcinomas than is
radium.
Staff Response - In assessing the bone cancer risk, the,Agency
assumed that plutonium, americium and curium are retained on bone
surfaces, and the risks have been calculated accordingly.
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23
24. Department of Energy
As a general comment, the EPA could have more justifiably
employed generally accepted dosimetric and risk estimation techniques
and parameters, such as those recommended by ICRP, NCRP, and in the
BEIR and UNSCEAR Reports. Where changes from these established
procedures seemed essential, because of important new information,
these changes should have been clearly justified. This was not done.
In fact, it is impossible to check any of the detailed models employed
or calculations made in arriving at the numerical values tabulated in
Annex III and Annex IV. These are referenced to unpublished EPA
documents, and were calculated by a computer code that is similarly
undocumented. ,
With the above very serious reservation, it must be acknowledged
that the numerical conclusions relative to dosimetry and associated
risk appear to be not grossly unreasonable, though sometimes stated in
a manner that exaggerates the confidence one is entitled to place in
such numbers. A few of the more serious shortcomings of the Proposed
Guidance, in this area, are discussed below.
Ingestion Route; Dose relationships involving transuranic
concentrations in soil or air are developed only for the inhalation
route. It is stated in many places that the inhalation route is most
important, and implied that if it is controlled, one can ignore
ingestion; however, in some other places it is stated that ingestion
may need to be considered. The conclusion that ingestion is
relatively unimportant apparently arose from an unjustified assumption
that environmental transuranics were always very insoluble, and from
lack of adequate consideration of external transuranic contamination
food. This conclusion was also supported by the use of a lung cancer
risk factor larger than is customarily assumed and a bone cancer risk
factor smaller than is customarily assumed. Although it does not
appear likely that ingestion will be a more important route than
inhalation for most exposed persons, it is not all unlikely that some
"critical segment" may receive a larger dose from ingested
transuranics than it receives from inhalation. It would seem
incumbent upon the EPA to evaluate the total pathway from soil to
cancer for the ingestion route, to the same degree that this has been
done for the inhalation route. The dosimetric behavior of such Class
W materials should be given consideration in this Guidance.
Presently, this consideration consists only of a reference to an
unpublished report. Appropriate consideration Class W compounds would
increase the relative significance of bone and liver cancers and
genetic effects, at the expense of lung cancers.
122
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24 •"-
Gonad Dosimetry: The treatment of gonad dosimetry and risk is
considered to be inadequate. The exact parameters employed for
dosimetric calculations are not defined in the Proposed Guidance, but
it is implied that the dose is taken to be half that calculated for
bone. This assumption seems to result from using the estimated
average dose to ovaries, and 2 to 3 times the estimated average dos?
to testes. The increase weighting of the testes dose is justified by
autoradiographic studies in mice that showed preferential deposition
of plutonium near spermatogonial stem cells. Recent studies indicate,
however, that differences in testes anatomy between mouse and man make
it unlikely that the same kind of non-uniform deposition observed in.
the mouse would affect the dose to spermatpgonial stem cells in man,
DOE Doc. LF-56, pp. ,389-403 (1976). There is also .evidence that
irradiation of; the mouse ovary is virtually without effect. It would
therefore appear that the estimates of genetic effect in the proposed
Guidance are too high by a factor of about five.
Canper Risk Estimates: Because of unavailable references, it is
impossible to reconstruct the total basis on which risk estimates were
derived The estimate of bone cancer risk was quite straightforwardly
based on the human 224Ra, data, and though one may quibble with the
validity of small corrections applied to the original observations-pi.
Spiess and Mays, the number arrived at is probably better, for
transuranics, than the considerably higher estimates of the BEIR
Report and ICRP Publication 26, It is not at all clear how the lung•.
cancer risk was derived. The result, however, reflects a greater risk
than has usually been assumed for lung irradiation. This combination
of a higher than usually assumed factor for lung cancer, and a lower
than usually assumed factor for bone cancer, results in the prediction
of an unexpectedly high ratio of lung to bone cancers. This may be as
good as any other estimate, but, because it is different, requires
justification that is not given in the Proposed Guidance.
Uncertainty of Risk Estimates; The general tone of Appendix III
implies a certainty with regard to risk estimates which is unjustified
and could be seriously misleading to responsible officials and to the
general reader, 'unaware of the uncertainty of many of the assumptions
employed. This Annex ignores express warnings of BEIR Committee and,
NCRP, concerning the need to qualify such estimates with a clear
statement of inherent uncertainties. The BEIR Report states
that" ..explicit explanation and qualification of the assumptions and
procedures involved in such risk.estimates are called for to prevent
their acceptance as scientific dogma". The Proposed Guidance states^
on p-3 of Annex III, "that for highly ionizing radiation such as .alpha
particles from plutonium the linear non-threshold hypothesis is
unlikely to overestimate the actual risks" (emphasis supplied;,, . The
highest and lowest of BEIR estimates are presented as a range
implying that the real number will fall somewhere between these
123
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25
numbers. Derived risk estimates are often given to 3 significant
°Uld -eem V6ry imP°rtant ^ a8document such as this,
a8enc^s and the public not be mislead. This is not a
of conservatism or lack of conservatism. The risks from
th nr/"7 1W 1?Vei\°f radia£i°n •« --Ply -t understood
the precision implied by many statements in this Proposed
Guidance. r
These general comments are abridged below in the staff response.
Staff Response - "EPA could have employed generally accepted dose
and risk estimation techniques and parameters." I,
rnmm...JheT^is.for this comment is not clear. ICRP Task Group and
Committee II dosimetry models were used throughout Annex III. ?he
essentials of the life table risk analysis used by the 1972 NAS-BEIR
Committee and in Annex III and IV are laid out on pages 171-173 of th*
1972 NAS-BEIR Report. Estimates of the lung cancer risk are taken
STi^S0" thS 19?2 MS-BEIR ReP°«s and the 1976 MS Report
T"ea: S E-ffects of Alpha-emmitting Particles in the Respiratory
Tract. Because the Agency's assessment of bone and liver cancer risk
are not found in the 1972 NAS-BEIR Report (where liver cancer was not
considered and the effects of bone surface seekers given insufficient
^rHST0-""' £8enCy ^^"^ ltS OWn risk "timates for these
cancers following the methodology described in the 1972 NAS-BEIR
Report. Over six pages in Annex III were used to document the
information used to develop the risk estimates for liver and bone
Aea£«* f I Agency has acknowledged in Annex III that the National
Academy of Sciences' ongoing review of radiation health effects
S" pr°Vide.f more CUrrent "Cation of the risk due to
than was available at the time the proposed guidance was
When the new BEIR Report is completed, ?he Agfncy wUl
1* eStimates in the ProP°^ guides to detfrmine if
changes are needed.
*™ ,Dose.Jela5ionshiPs applicable to the ingestion of transuranics
are described in Section 3.4.4., PP. 10-21 of Annex III. Table A 3-6
gives the dose to various organs due to the ingestion of four
transuranics and Table A 3-7 for six. Table A 3-8 gives gonadal doses
due to ingestion for six transuranics and Table A 3-9 HsL do^e due
to chronic ingestion by infants.
No basis for the DOE assertion that "Transuranics other than
Plutonium are now considered to behave as Class W materials" is
S£ *f-6V f Xt haS been rum°red that the ICRP is considering the
classification of some transuranics in the W category, it has been thl
Agency's experience that ICRP's published reports can diffe?
P,1;f^fanJlyi5r0m hea"ay about their contents. Obviously Federal
Guidance should not be based on hearsay. The dose and risk for Class
W compounds are discussed in Section 6 where it is shown that the risk
prepared
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26
due to the inhalation of Class W compounds at the proposed dose rate
limit is comparable to that for Class Y compounds.
25. Department of Energy
Since there have been many recent and extensive published reviews
and collections of information on the biological properties and
effects of the transuranium elements, it seems unncessary to provide a
single reference to an unpublished document, (p-1, lines 13-15)
Staff Response - The document referred to contains 30 pages and
cites over sixty publications in the sections providing information on
biological properties and effects. Publication of this material
separately was the result of an editorial decision favoring a short??
Guidance document. Xerox reproductions of this material were provided
to the commentors in 1977. -
26. Department of Energy
The implication that we know little about transuranics in gonads
is misleading. The fraction deposited in gonads is somewhat uncertain
only because it is so small as to be difficult to measure in the
general population, (p-1, line 9)
Staff Response - The available data is neither extensive nor
persuasive. Animal data shows such a wide range of inter-species
variability that its application to man is tenuous. Variability in
the human data is in part due to measurement difficulties. Moreover,
there is no data on distribution patterns in human gonads and very
sparce data for animals. These data are reviewed in the guidance
document.
27. Department of Defense
The literature abounds with information on the biological
properties of transuranium elements; therefore, why reference an
unpublished review? Is it because it is an in-house pub?
(p-1, p-2)
Staff Response - See response to comment 25.
28. Department of Energy
The statement in Annex III that refers to the "procedure used by
the BEIR Committee in arriving at its best estimate of radiation
risV. To refer to anything from the BEIR Report as a "best estimate"
125
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27
seems contrary to the spirit of that report, which was, in most
instances, careful to qualify its estimates as "fraught with
uncertainty". Only in their Summary and Recommendations did they
quote a "most likely" estimate, which is a statistical "most likely",
assuming the accuracy of their models (an assumption they were
elsewhere careful to avoid).
(p-2, lines 19-22)
Staff Response - The phrase "most likely estimate" not "best
estimate" is correct. It appears in at least four places in the 1972
BEIR Report, (pages 90, 91, and 168) where it is used in the sense
outlined in the comment, and also in the "Summary and
Recommendations", (page 2). In the latter case it means the
Committee's "best" guess given the range of values that can be
estimated using the various models and risk coefficients given in the
report. It is clear that the Committee did not believe their "most
likely" estimate was very accurate, nor does the Agency believe so.
Rather, the point of the cited sentence was to indicate that the
method of averaging used by the Agency results in numerical agreement
with those labeled as "most likely" by the Committee.
29. Department of Defense
The BEIR Committee Report takes great care in explaining what
their "best estimates" mean. This document should at least
acknowledge that there are qualifications surrounding the estimates
and not present it as scientific fact, (p-1, p-2)
Staff Response - See response to comment 28.
30. Department of Energy
It is not clear what is referred to by the phrase "risk estimates
listed below", (p-3, Line 6)
Staff Response - The phrase refers to risk estimates in Annex III.
31. Department of Defense
What risk estimates below? Those being derived by EPA, those
taken from elsewhere or what? Also, is any model "appropriate"?
(p-3, line-4)
Staff Response - See response to comment 32.
106
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32. Department of Energy , ; , .
The phase, "which of these models is appropriate", implies that
one ;of them is appropriate, which does not necessarily follow.
(p-3, line, 7) ,.'.:.. . - ,,. ,,
Staff Response - The Agency disagrees. There is a growing body
of evidence that the absolute risk model is applicable to
radiation-induced leukemia (and ..perhaps, bone cancer),-while models
which,-incorporate, the increased risk of cancer with advancing age :are
a better choice for such common cancers as breast and lung cancer.•-,-•
Ref: The Latent,Period of Radiogenic Cancers Occurring Among Japanese
A-Bomb Survivors, ,C. E, Land and J. E. Norman, IAEA Late Effects
"Symposium, Mar eh,, 13, 1977 i Vienna. ,« ...
33» Department; of Energy ,.'.. .
.If, as the agency recognizes in the latter part,of this sentence,
the risks are based upon a hypothesis, by definition the risks are
hypothetical.
The statement "that linear non-threshold., hypothesis is unlikely
to overestimate the actual risks", implies a certainty with"regard to
risk estimates,that was not shared by the authors of the BEIR Report,
who cautioned that "the foregoing estimates ..of mortality from . ., -
radiation exposure may be -too.high, ,or too. low, for. a.varietyspf
reasons", (p-3, lines 14-17) •
35. Department of Defense
This entire paragraph is a distortion. Contrary to the statement
that "the agency dose not consider the risks due to ionizing radiation
hypothetical...", the fact remains that they are hypothetical as
estimated by the Agency. (p-3, line 2) ; „-.,.-.
Staff Response - Due to ou,r
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29
35. Department of Energy
The reasoning of this paragraph is difficult to follow. It seems
to be justifying an increased dose to children on the basis of an
insignificant change in lifetime risk, but neither the increased dose
to the child, nor the effect on lifetime risk, is adequately defined.
Since the basic Guidance is terms of dose per year, not risk, the risk
argument is technically irrelevant. (p-4, line 17 to p-5, line-3)
Staff Response - Section 1, pages 17, 23 and particularly the
footnote on page 24 indicate clearly that this numerical Guidance
applies to adult organ doses. No attempt is made in the Guides to
justify the risk to children. Rather, the increased dose and risk to
children has been: considered in the estimates of,the:risk due to ,
lifetime exposure. The pulmonary dose to children is;about one and a
half times greater than that to adults. This may increase the ,;
lifetime risk by about ten percent. . ... ,
36. Department of Energy
The "logarithmic averaging" requires further description and
justification. To imply that other conservative assumptions will
balance a nonconservative bias, without identifying or quantifying
these assumptions, confuses the analysis, (p. 5, lines 17-22).
Staff Response — The Agency does not endorse the exclusive use of
either the largest or smallest risk values that can be generated with
the BEIR risk models. The Agency's use of logarithemic averaging of
the various 1972 BEIR risk estimates yields numerical results that
agree with the BEIR Committee's "most likely" estimates. However, as
stated in the Guidance document such a procedure weighs absolute risk
estimates somewhat more heavily than the relative risk estimates. The
degree of bias this introduces is small compared to.the uncertainties
in the risk estimates, e.g., for the case of lung cancer mortality,
about ten percent. No attempt was made to offset indeterminate
quantities.
37. Jefferson County Health Department ,
The dose and risk to health due to inhalation and ingestion of
transuranium nuclides. On page 4 there is an inadequate explanation
for the choice of the term "rad" in place of the more commonly used
"rem". In a few years the dosage from.gamma radiation from americium
can be significant harzard in areas contaminated with transuranium
element. There is adequate justification to use the more conventional
term, "rem" in order to reduce radiation effects to a common
denominator. Consequently, I recommend that the terms rad or millirad
be converted to rem and millirem throughout this document.
128
-------
30
Staff Response - The rem is not an appropriate unit for risk
analyses since RBE and quality factors differ for various biological
end points, see response to comment .92.
38, Jefferson County Health Department
In the last paragraph on page 4, the report states, "this
provides a conservative estimate of childhood dose since deposition
and retention in the lung should be less for children due to their
smaller lung area". This is probably not correct, because of the
higher metabolic rate and the greater physical activity of children.
In'addition, children spend much more time outdoors and are breathing
air more near the surface of the soil than are adults. On page 5 it
is!noted that the Agency has chosen a less conservative relative risk
model for children rather than the more conservative model which
assumes children are ten times more sensitive to radiation than are
adults. .
Staff Response - The Agency utilized data on age specific minute
volume, airway dimensions, and lung surface area to calculate the
maximum that pulmonary deposition as a function of age. Deposition
peaks around age 10. At this peak period, deposition per unit area is
about twice that in infants and adults. The Agency's-use of this
value is likely to be slightly conservative since this occurs for only
a few years during which the body is growing rapidlyi Moreover, the
contribution to lung dose and body burden from material inhaled during
this period would probably be reduced by faster clearance, (the
distance material travels to be cleared is shorter). Unfortunately
these facts were not clearly stated in the paragraph.
39. Department of Energy
The triple negative in this sentence makes it very confusing.
(p-5, lines 20-22)
Staff Response — The sentence should read "It is unlikely that
the true risks are underestimates."
40. .Department of Energy
. - t
The reasons given for "expecting" that inhalation will be "the
most important pathway" are vague and insufficient. The conclusion,
itself, will be questioned by some, (p-6, lines 2-15)
Staff Response - The amount of food and water coming from
contaminated land and ingested by those inhabiting this area could be
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31
highly variable and certainly circumstances could arise where the
ingestion pathway is predominant, at least for a limited time.
Nevertheless, breathing on the part of inhabitants is inevitable and
contaminated air is not as readily replaced as food and drinking water.
^•1* Department of Defense
The reasons given do not support the conclusions stated.
(p-6, para. 1) ,
Staff Response - See response to comment 40. \
42. Department of Energy '
These statements are correct only for a highly insoluble form of
inhaled plutonium. Dose to liver and bone, relative to lung, and the
temporal pattern of this dose, will vary widely depending on the
nature of the inhaled material. The lack of consideration of anything
other than very insoluble forms is a consistent weakness of this Annex.
(p-7> lines 10-14)
Staff Response - The statement is true for Class Y compounds.
Class W compounds are discussed in Section 6. ...
43. Department of Energy
Again, the emphasis is on "highly insoluble transuranics,"
with'no mention of more soluble transuranics. In fact, 239puQ2 is
probably the only compound that would qualify as a /'highly insoluble
trahsuranic" in the context of this sentence, and even this may be
questionable. (p-7, line 25 to p-8, line-3)
Staff Response - See response to comment 42.
44. Department of Defense
It is not clear that administrative controls have any -
relationship with chosing the specific model. It may he fortuitous.
(p-7, line 16) ,
Staff Response - (The comment is unclear).
45. Jefferson County Health Department
In paragraph two on page seven, the report states "the uptake by
plants is relatively small, and most animals, including humans, have a
130
-------
---•-"32 •,,:.
high discrimination factor against transfer of these elements into the
body tissues". However, some plants, such as algae and seaweed, have
the ability to concentrate plutonium, presumably in a form that can be
assimilated by animals. Chelating agents present in soils over a
period of time may make the plutonium oxide in soil available for
uptake by both plant and animals to a greater extent. (P-7)
Staff Response - The increased availability of transuransics
after a period of time is covered by the Agency's use of increased ,
absorption by a factor of 5 to 50 for biologically incorporated
elements as compared to elemental forms.
The Guidance is based on a dose limit (rather than a maximum
permissible concentration) and is therefore independent of the form
encountered which must be considered on a site specific basis.
46. Department of Energy - • -,
.Should "reference 5" read "reference^"? Fig. A 3-2 seems to be
from (5), but Table A 3-1 is from (4), and they are not completely
consistent, as noted later. (p-9, line-11)
Staff Response - Yes. . " r i
47 . Department of Energy
Justification.and/or references should be given for the
contention that environmental plutonium and other transuranics "are
likely to"be in the oxide or hydroxide form." There is considerable
recent evidence to the contrary, particularly for the transplutonium ..„
elements. This becomes important for estimating doses due ,to
ingestion and for the determination of the ICRP lung dose.
(p-9, lines 15-18)
Staff Response - See Section 3.2, Annex II, response to comment 2.
48. Department of Defense
What is evidence for saying environmental sources of^pl
are likely to be "in oxide or hydroxide form"? In general, all the
material here and preceeding seems to be biased toward insoluble
transuranics with little regard for soluble forms. •"--- -
(p-9, line 15)
•• • •- -, •'. ,' .' ;.,': . -• :... • r. • •<••' .- I t'
Staff Response - See Section 3^2, Annex II, response to comment 2.
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33
49. Department of Defense
Same comment applies here with regard to unavailability of
reference as was pertinent for the reference on the PAID code. One
must accept the dose estimates calculated by EPA. (p-9, line 22)
Staff Response - The PAID code has been documented and published
as EPA document, Technical Note ORP/CSD-77-4. See also response to
comment 52.
50. Jefferson County Health Department . . ;
On page nine, the report notes that insoluble actinides have an
estimated biological half-life in pulmonary tissue of.500 days. .
Plutonium and the other actinides leave the lung by the transport of '
particulate materials into the lymphatic system to the lymph nodes, or
by elevation up the tracheobronchial tree, or by dissolution into the
blood stream. It must be noted that the particle size of the
respirable fraction of these particles is in the same order as
bacteria, which likewise are .able to be transported about the body;
The estimated biological half-life of plutonium in the liver is
assumed to be 40 years and for bone, 100 years. (p-9)
Staff Response - Although both bacteria and respirable particles
can be transported to various body organs via blood, direct comparison
is inappropriate because of the higher density of plutonium and
differences in physiological transport mechanisms.
51. Department of Energy
"only retention in the pulmonary region" receives
attention. The sentence is incorrect except perhaps, for highly
insoluble 239Pu02- (p-10, lines 3-5)
Staff Response - Perhaps the sentence is not clear. This
paragraph is comparing the dose to various compartments within the
lung, not the dose to the pulmonary lung relative to other organs; In
this context, the statement applies equally well to the more soluble
Class W compounds. The sentence would be more clear if written; "In
assessing the lung dose and risk due to the inhalation of Class Y
transuranium elements, only retention in the pulmonary region is of
primary importance."
52. Department of Energy
The unavailability of the PAID code precludes any possibility of
checking dosimetric calculations, (p-10, lines 18-21)
132
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""'34' ,. -•*".;... .;.....-.. . •.
Staff Response - The PAID code was made available to DOE
reviewers in January of 1978. Published references cited in the text
Annex, (7,8), contain essentially the same derivations as those given
in the -PAID; documentation. The extension of these derivations to
include the dose due to the daughter products of initially deposited
parent radionuclides is straightforward.
53. Jefferson County Health Department
The last paragraph on page ten notes that the ICRP model is based
on ambiguous equations, but in turn is used to calculate the annual
dose rates resulting from inhalation of isotopes of plutpnium,
americium and curium for a number of particle sizes. This ambiguity
is important to note, since such calculated doses are often presented
with an air of.unwarranted precision. (P-10)
Staff Response - The statement was apparently misread. The ICRP
Report does not provide unambiguous equations. The PAID code for
calculating doses and dose rates does use documented equations and a
well-de-fined model based on the ICRP Task Group Report (Reference 5,
Annex III). However, the reference to "unwarranted precision" is
appropriate in view, of possible differences between actual exposures
and the results predicted by the task group lung model.
54. Jefferson -County Health Department
On page eleven, the last paragraph, the report states that the
high dose rate to the tracheobronchial lymph nodes is "not believed to
be an important consideration in estimating risk" because of animal
studies. I would question this assumption, in view of the length of
life of man ;in relation to the length of the animal; study periods.
(P-ll)
Staff Response - Although only the statement that "the lifespan
animal studies showing that the frequency of respiratory lymph node
cancer is negligible compared to other cancers caused by transuranics"
was referenced in the ORP support document, there is also human data.;
Respiratory lymph node cancers have not been reported in uranium or
other1 miners who have deposited inhaled uranium ore dust. Neither has
lymph node cancer been associated with Thorotrast exposure even though
Thorotrast does deposit in lymph nodes. There is no evidence reported
of risk related to deposition of radioactive material in lymph nodes
at this time in either man or animals. •*
55. Department of Energy
The section heading refers to the dose.to the total body, but
there is nothing in the section about total body dose, (p-12, line-1)
IBB
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35
Staff Response - Total body doses are discussed only for the case
of ingestion (Table 6-6) and should have been omitted from the heading
referred to.
56. Department of Energy
A reference should be given for the statement that half life for
transuranics in gonads may be longer than 100 years. It might be
better simply to state that the amount present is too small to study
the rate of release. (p-12, line-10)
Staff Response - Fish, et al., B. R. Fish, G. W. Keilholtz, W. S.
Synder and S. D. Swisher, Calculation of Dose Due to Accidentally
Released Plutonium from an LMFBR. ORNL-NSIC-74, USAEC, Oak Ridge, 1972
reference an estimate of infinite retention in gonads. They do not
mention that the amount is too small to study.
Moreover, studies by D. M. Taylor reported in "The Uptake,
Retention and Distribution of Plutonium-239 in Rat Gonads", Health
Physics 32^:29-31 (1977) indicate a variety of transuranics show no
appreciable loss from the gonads. Again no problems in measurement
were noted.
57. Department of Energy
Again, the Class Y .assumption is unjustified for amerieium and
curium. Why is 239pu specified as the oxide, while other compound
forms are unspecified? (p-12, lines 18-21)
These calculations apparently assume (one cannot be sure without
Ref. 6)'a constant concentration of transuranics in air over the 70
years of exposure. This does not appear appropriate,, particularly for
the shorter-lived transuranics, since the concern is for single event
contamination of soil.
Staff Response - All actinides (including amerieium and curium)
are currently classified by ICRP as Class Y if in the oxide or dioxide
form. :
The chemical form is specified for Pu-239 oxide because a portion
of the dose to liver and bone due to inhalation depends on the
transgut transfer of material swallowed after the inhaled material is
transported up the bronchial tree. For the Pu-239 calculation, the
gut transfer for the oxide forms (0.0001) was used since it is the
case most likely to be encountered in the general environment. Doses
for amerieium, curium and high specific activity plutonium oxides were
calculated for a gut transfer of 0.001 as in Table A 3-5 of Annex III.
134
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36
- • ?•'-"-" ~-X-,.-- . «;
The assumed duration of the chronic exposure is for a lifetime.
Tables A 2-3 and A 3-3 are clearly labeled "Duration of'Exposure" and
go up to 70 years. It is likely but not inevitable that the
concentration of shorter lived transuranics in air will vary with the
half life of the radionuclide since the long term resuspension rate is
likely to be constant. The Agency agrees that in many cases
radioactive decay will reduce exposures from the shorter half life
transuranics. .
Table A 3-4 gives concentrations based on a constant annual'' r
intake. However, Table A 3-4 is not the Guide, and need not be used ^
where it can be shown, on a site specific basis, that the pulmonary
dose, rate of 1 mrad per year is not exceeded. -
58. Department of Energy : ; . -,
The statement probably is not true. Much of the liver deposit
may derive, from particulate material transferred via lymphatics.
(p-12, line-25 ,to p-13, line 3), ; , .•
Staff Response: - The sentence, is not well worded. A better
sentence would be: "Almost all of the dose to liver and bone is from
material in the lungs and lymph nodes that has been transported via
the blood to the bone and liver."
Phenomena of pinocytosis and macrophage transport are mentioned
in a.section on "The Physiological: Basis of Transuranic Element Dose
Estimates" in Annex IIIj Reference (1), but the extent of their
contribution to transport of nuclides in the body is not known.
See J. A. Schallberger, M. W. Dewhirst and J. L. Lebel "Lymph
Transport of Soluble and Insoluble Plutonium" pp. 19-27 in Radiation
and the Lymphatic System, ERDA Symposium Series 37, 1976, for~
additional : information-. ..-..-•- •-. •-,..-.
59. Department of Energy
"0.09%" should be "0.009%" (p-14, line-22)
Staff Response - 0.09% is a misprint; 0.009% was used in the
calculations.
.- ) ' '.-•,-, " -. ...'., !-.
60. Department of Energy .,..
Although discussed, the concentration of transuranics in gonads,
necessarily assumed by EPA for dose calculations, is nowhere stated.
(p-14, line-20 to p-15, line-8)
135
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37
Staff Response - It was assumed in Annex III that 0.0045% per
gram of the transuranic material in the blood is concentrated in
gonadal tissue for both females and males. Since the concentration in
bone is 0.009%, the gonad dose rate is half that of bone tissue.
61. Department of Defense
The ICRP model uses 0.009%, not 0.09 (p-14, line-22)
Staff Response - See response to comment 59.
62. Department of Energy
Because of differences in testes anatomy between mouse and man,
it seems unlikely that the same kind of non-uniform deposition
observed in the mouse would have any effect on the dose to
spermatogonial stem cells in man. (See A. L. Brooks, J. H. Die! and
R. 0. McClellan, LF-56, 399-403 (1976)). (p-15, lines 1-4)
Staff Response - The question of anatomy of the testes is not of
prime interest in determining the dose to spermatogonia. What is
important is the micro-distribution of plutonium and other transuranic
elements. Distribution of plutonium differs between rat, mouse, and
hamster testes, as discussed in Annex 3. Green, et al., Nature 225:77
(1975) stated that plutonium appears to be deposited in intertubular
spaces (^47%) and in peritubular tissue (^42%). Data on man and other
species is needed to resolve the question. The dosimetry of plutonium
in gonads is discussed in reply to comment t24 and also in "Selected
Topics: Transuranium Elements in the General Environment," Tech. Note
CSD 78-1, referenced in Annex III.
63. Department of Energy
Parenthetical statement is no longer correct. A recent study in
rats concludes that "the concentration of alpha tracks over the mature
or developing follicles and corpora lutea was only 10% of the
concentration over corresponding areas of stroma". (See D. M. Taylor,
Health Phys. 3.3:29-31 (1977)). (p-15, lines 4-5)
Staff Response - A more exact quote from Dr. Taylor is: "Only
very limited autoradiographic studies were carried out on ovarian
tissue and these suggested that the concentration of alpha tracks over
the mature or developing follicles and the corpora lutea was only
about 10% of the concentration over corresponding areas of stroma.
(D. M. Taylor, Health Physics _32:29-31 (1977)>.
136
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38
Data developed from high resolution autoradiography by N. D.
Priesti Int. J. Radiat. Biol., 31:59-78 (1977) shows the answer is far
from clear at this time. Data of -Green, et-al., Int. J. Appl. Rad.
Isot.3 28:497-501 (1977) shows there is redistribution in the ovary
with increasing time after exposure. Obviously while some information
has been available, further data on distribution of transuranics in
the ovary should be obtained.
64. Department of Energy
Use of a 30-year dose in considerations of genetic risk is
justifiable only on a population average basis. This Guidance is
supposed to protect the "critical segment" of the population, which in
this case might be the 70-year-old men still producing children.
This,''again, points out the lack of definition of this "critical"
segment. (p-15, lines 14-16)
Staff Response - A critical receptor is not addressed in these
risk estimates. All risk estimates both genetic and somatic are in
terms of the number of health effects per"100,000 persons exposed.
Consideration of a critical .segment of the exposed population refers
to the dose calculation, not the risk calculation. The critical
segment of the exposed population is defined in the guides; see also
response to comment 35. In passing, it might be noted that only about
3 in 1000: families with the head of the household over age 65 have
children under 3 years of age. Thus, those.age 70 males are not a
problem. (Population Characteristics 1973,: Department of Commerce
Series P^-20, #258, 1973)
65. Jefferson Health Department
On page fifteen the report states that for an equilibrium
pulmonary dose rate of one millirad per year, the dose rates to
genital tissue in the first 30 years of.life is calculated to. be 1.4
millirad. Does this estimation take into account the pattern of
microdeposition of-plutonium in the testes which would give a higher
value in millirem than might be anticipated from the actual amount of
plutonium present in the testes? (P-15)
Staff Response - Yes, the gonadal dose calculated for
transuranics does take into consideration the nonuniform distribution
of the isotope in gonadal tissues.
66. Department of Energy
The statement is incorrect. Many soluble compounds have been
employed in studying absorption of transuranics from the gut. The
most extensive studies employed nitrates. (p-16, lines 14-17)
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39
Staff Response - The statement only compares laboratory prepared
plutonium oxides to plutonium oxides found in the environment. It
does not address transuranics in general. ,
67. Department of Energy
It is not clear why "conservative estimates...are required".
There are risks of erring in either direction. (p-16, lines 17-19)
Staff Response - The risk of over estimating the dangers of
plutonium were considered in the development of these guides.
68. Department of Energy
The choice of transfer coefficients is presented as an arbitrary
decision with inadequate justification for the exact numbers chosen.,
It is not clear that the usual conservatism "applicable to public
health problems" is justified by the very limited problem associated
with transuranics in the environment. This does not seem to be a
public health problem in the usual sense: of the term.
(p-16, line-19 to p-17, line-2)
Staff Response - The Agency's selection of gut transfer
coefficients was largely based on the.recommendation of
Battelle-Northwest Laboratory scientists having, as a group, the most
extensive experience in this field. See section 6. •
69. Department of Energy
Sentence is correct only if 239pu aiuj 240pu are excluded.
Absorption of these isotopes, assumed to be oxides, is increased
50-fold by biological binding, according to Table A 3-5; 10%
biologically incorporated would result in 590% increased absorption of
239PUj240Pu> (p-18, lines 5-6)
Staff Response - The dose caused by the biological incorporation
of 239pu or 24Gpu oxides is essentially the same as for 238pu
and 24-l^jj £n the same form. While the comment is mathematically
correct it is logically inconsistent. The EPA statement was based on
the most soluble transuranics becoming available for incorporation
into ten percent of the diet. A similar chain of events would lead to
one percent incorporation for the less soluble oxides of 239pu anc]
240Pu.
138
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40
70. Department of Energy
Sentence implies that gonad deposition is important and that it
is a primary site of deposition, second only to liver and bone; this
is misleading. (p-18, lines 7-10)
Staff Response - In view of the relative importance of genetic
consequences, the long retention of transuranics in gonadal tissue,
and the possible micro deposition of transuranics adjacent to
sensitive cells, the Agency believes the dose to gonadal tissues
deserves careful consideration.
71. Department of Energy
It appears that calculations are made assuming that the source is
continuously renewed and a constant amount taken in over the 70-year
period. This is inappropriate when soil is the source, especially.for
the shorter-lived transuranics. (p-18, lines 21-24)
Staff Response - The Guidance document stated on page 111-19 that
"the occurrence of lifetime ingestion Is remote". However, renewed
contamination is not the only way long term exposures could occur
since patterns for ingestion are a function of land use. The Tables
are not the Guides. When doses are expected to decrease so that there
is a high probability that the bone dose in the 70th year would not
exceed 3 mrad, this should be considered in the implementation of the
guidance.
72. Jefferson County Health Department
On page sixteen the report states "plutonium oxide found in the
environment has been shown to be much more soluble than the refractory
oxide utilized in animal experiments". The report states (page 19)
that organ dose rates listed in Table A 3-6 were calculated on the
basis of organ masses appropriate for a reference .man but not for
children. The report also states that there is some evidence from
studies of newborn animals of a high .rate of transfer of transuranium
elements across the gilt wall to blood. On page twenty-one the report
notes that the transfer of americium and curium across the gut wall is
about 100 times greater than for other transuranium elements. (p-16,
line 19)
Staff Response - Contrary to this comment, age-specific dose
calculations for ingestion based on organ masses for children were
made and reported on .page 20 and Table A3-9 of Annex III for the case
of ingestion by infants, the limiting case. As pointed out in Annex
III, children's organs are changing mass rapidly, so that the
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41
incremental change in total dose or in dose rate at age 70 was less
than +10%. This was not considered enough difference to justify
age-specific intake calculations. Dose rates and radiation risks for
inhalation were calculated on an age-specific basis.
The statement on page 21 Annex III was misread. The statement is
"Transfer of americium and curium to milk is about 100 times greater
than other transuranium elements..." not that the transfer across the
gut wall is 100 times greater.
73. Department of Energy
The reference to Section 3.4.3 is inappropriate, since this
Section does not describe in specific detail how gonadal dose has been
calculated. (p-19, lines 13-14)
Staff Response - Agreed, only the rationale was described in
Section 3.4.3. However, see reponse to comment 60.
74. Department of Energy
This statement should be referenced. (p-19, lines 19-23)
Staff Response - High gut transfer of transuranics in the newborn
is discussed in Reference (1), Annex III. Also in Section 6, W. J.
Bair and R. C. Tompson, letter communication (1977).
The basic references include ICRP Publication 19 (1972); W. J.
Bair, pp. 171-230 in WASH-1359, 1974; M. F. Sullivan and A. L. Crosby,
BNWL-1950 (1975) and BNWL-2000, pt. 1 (1976). M. F. Sullivan,
PNL-2500, Pt. 1 (1978) provides futher data.
75. Department of Energy
Ref. 15 appears to be an error. (p-20, line-7)
Staff Response - Reference 15 is a misprint. Reference 25 is
correct.
76. Department of Energy
This argument should be further developed, since the referenced
paper is not readily available. How different were the doses, and was
the possible promoting effect of cigarette smoking controlled?
(p-22, lines 1-7)
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--42 ' .....
Staff Response - The material referenced is also discussed by R.
W. Cihak, et al., Cancer, 33:1580-1588 (1974)) under the same title.
A follow-on article on Smoking, Occupation and A-bomb Exposure
(T. Ishimaru, £t al^, Cancer, 36: 1723-1728 (1975) reports that a
Mantel-Haenzel analysis of four-fold tables indicates that the
reduction in (Chi) when adjusted for smoking"... is not large enough to
suggest a confounding of smoking with radiation dose..." The most
these authors could conclude was that the data they had did not by
itself provide any suggestion of non-additivity of the effect of
radiation and the effect of smoking, when those exposed at less than
1 rad and those exposed at 200+ rads, were compared.
77. Department of Energy :
Reference 35 is another critical reference which is unpublished,
and Annex 4 does not describe the procedures employed in sufficient
detail to check the accuracy of the Table A 3-10 and subsequent
similar tables, (p-24, lines 14-16)
Staff Response - The life table analysis used by the Agency is a
straightforward application of the risk assessment methodology
developed by the NAS-BEIR Committee to prepare their summary tables of
effects, see particularly Table 3.1, 3.3, and 3.4 in the 1972 NAS BEIR
Report. The EPA analysis is based on a stationary population and risk
of particular rather than all cancers. A general description of the
model was given in Annex IV of the Guidance document.
78. Department of Energy
It is not clear what is meant by "averaging the geometric
means", (p-25, lines 3-5)
Staff Response - Adding the geometric means -and dividing by two.
79. Department of Energy
While it is impossible to check the calculation because of
unpublished critical references, it should be noted that the lung
cancer risk listed here is about 5 times higher than either the
Medical Research Council's (England) estimate, or the estimate of ICRP
Publication 26. (p^25, lines 14-15)
Staff Response - The MRC adopted the 1972 BEIR Committee's lowest
risk coefficient, 1 case per 10^ person years at risk per rem and 25
years at risk for occupational exposure. The "EPA analysis is not
141
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43
based on occupational exposure and necessarily considered a longer
period of risk, i.e., lifetime risk. Moreover, EPA utilized BEIR
estimates of the risks due to exposure during childhood, a factor not
considered by the MRC. The Agency has also included estimates based
on the relative risk of radiogenic cancer. The ICRP gave no
information on how they derived the risk estimates published in ICRP
#26. Since they were considering occupational exposure, their
analysis may have had much in common with that of the MRC.
80. Department of Energy
"140 bone cancers per 106 rad " (p-26, line-16)
S|aff Response - Agreed. There was a misprint. 140 bone cancers
per 10^ rad is correct.
81. Department of Energy
Marshall's statement should be referenced. (p-26, line-23)
Staff Response - The appropriate reference for Marshall ejt al.:
J. H. Marshall, P. G. Groer and R. A. Schlenker "Dose to Endosteal
Cells and Relative Distribution Factors for Radium-224 and
Plutonium-239 Compared to Radium-226", presented at the 1976 Alta
Symposium, Health Physics, in press.
82. Department of Energy
The bone cancer risk employed is considerably lower than the
estimate one would derive from the BEIR Report. Should this not be
acknowledged? (p-28, lines 13-15)
Staff Response - The EPA bone cancer risk estimates are somewhat
larger than those prepared by the 1972 BEIR Committee on the basis of
earlier data. The estimates of bone cancer are risk based on human
exposures due to 244fta- The BEIR absolute risk estimate for 224Ra
is 9.6 sarcomas per 106 skeletal rad per year at risk, (page 128 of
the 1972 BEIR Report). However, as the BEIR Committee pointed out on
page 127 of their Report, long-term exposure to 2^Ra increases the
incidence per rad by a factor of about two. Since transuranics
incorporated into bone yield chronic not acute exposures, the EPA
estimate is based on prolonged exposure, i.e, 25 per 10^ skeletal
rad per year at risk, (page 28 of Annex III).
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44
83. Department of Energy
Dose values shown in Table A 3-11 apparently assume continuous
input over 70 years; if so, this is inappropriate, particularly for
soil contamination by the shorter-lived transuranics.
(p-29, lines 8-10) '
Staff Response - See response to comment 57.
84. Department of Energy
The reason given for not considering "relative risk" for bone
cancer is not clear, (p-29, lines 11-16)
Staff Response - The human data for the persons treated with
indicates a finite plateau period; in such case, use of an
absolute risk model is warranted. By definition a relative risk model
assumes that the time pattern for the occurrence of radiogenic cancers
is the same as that for the "naturally" occurring cancer.
85. Department of Energy
Bone cancer risks of Table A 3-12 apparently assume continuous
input over 70 years, which again would be inappropriate, particularly
for soil contamination by the shorter-lived transuranics.
(p-29, lines 22-23)
Staff Response - See response to comment 57.
86 . Department of Energy
Sentence is not clear. (p-29, line-23 to p-30, line-2)
Staff Response - The sentence is poor. The point to be made is
that even though the risks from 3 mrad alpha dose to the bone in the
70th year, following continuous ingestion of 239pu or 241^ are
similar, (see Table A 3-12) the dose per unit of activity ingested is
10 times higher for ^Am than for 239pu (see Table A 3-7).
Therefore, the maximum amount ! of 241^ that could be ingested under
the Guidance would be 10 times less than the amount of 239pu that
could be ingested.
87. Department of Energy
Statement is misleading. The magnitude of the potential risk was
143
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45
inferred from animal data long ago. It has received support, more
recently, from Thorotrast patients. (p-30, lines 15-17)
Staff Response - The possibility of liver cancer associated with
actinides but not the magnitude of risk was shown by animal
experiments. The Agency prefers to use human experiences as a basis
for risk estimates and support this with animal data where necessary.
88. Department of Energy
Statement regarding the abundance of animal data should be
referenced. (p-31, lines 21-25)
Staff Response - References to animal data on liver cancer
induced by plutonium should include: L. A. Buldakov, et al., Problems
in Plutonium Toxicology LF-tr-41, 1970; G. N. Taylor £t al., pp.
105-127 in Radiobiology of Plutonium, 1972; G. N. Taylor, e± al.,
pp. 523-536 in The Health Effects of Plutonium and Radium, 1976.
89. Department of Energy
Reference 15 appears to be an error. (p-32, line 21)
Staff Response - Reference 15 is an error. Reference 6 should be
indicated.
90. Department of Defense
Reference (15) discusses gonadal tissue, not liver.
(p-32, line-21)
Staff Response - See response to comment 89.
91. Department of Energy
The concept of an equilibrium dose from a short-lived transuranic
is not consistent with a single-event contamination.
(p-33, lines 11-14)
Staff Response - See response to comment 57.
92. Department of Energy
The ICRP factor of "20" should be referenced to ICRP Publication
#26. It is a Quality Factor "intended for use only in radiation
-------
46
protection and then for comparing actual levels of exposure with the
limits of dose equivalent... These values.of Q are therefore not
necessarily representative of values of relative biological
effectiveness for other observed effects, such, as stochastic effect in
animals at low levels of absorbed dose". (emphasis added). If the
number 20 is to be used as an RBE, not as a Quality Factor, it should
be justified. (p-34, line 7-10)
Staff Response - Agreed. Scientific evidence supporting the
Agency's choice of RBE of 20 compared to x-rays was provided in the
Guidance document. (Reference 45, Annex III).
93. Department of Defense
There is a loose association here between RBE and QF. The ICRP
does not assign an RBE of 20 for alpha, it says the QF is 20 for.
radiation protection purposes. (p-34, line-7)
Staff Response - See response to comment 92.
94. Department of Energy
The origin of the factor "5" in "100 (5x20)" is not clear.
(p-35, line-1)
Staff Response — The reduction in genetic effects due to low dose
rate low LET radiation in the 1972 BEIR Report is 3.4 for males and
infinite for females. Because the Agency is unconvinced that low dose
rate, high LET particles will not affect the genetic competency of
mature oocytes, the factor of 3.4 was arbitrally increased by 50
percent to 5.
95. Department of Energy
This sentence is misleading. The "other analyses^1 are supported
by only a single reference, and the "underestimate" is relatively
insignificant compared with the overestimate alleged in Ref. 49.
(p-35, lines 8-10)
Staff Response - Although, as Ash, et al. point out: "The
question of whether multifactorial disorders should be.considered in
assessing the risks of ionizing radiations is one of semantics, for if
multifactorial diseases are maintained by mutations, they are
essentially monogenic." (Ash, et al., J. Med. Genetics, 14:305-306
1977). The Agency has treated multifactorial genetic disorders as
distinct entities.
145
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47
References for the possible underestimate of multifactorial
disease in the 1972 HAS BEIR Report include: Development of Common
Indices for Radiation Health Effects, Final Report to EPA, A. D.
Little, Inc., 1974; Sources and Effects of Ionizing Radiation UNSCEAR
Report, 1977 and abridged versions of papers presented at an MRC forum
on hereditary disease in man, Journal of Medical Genetics, 14:305-331,
1977.
96. Department of Energy
Limiting gonadal dose to 30 years is a "population risk"
assumption that has questionable applicability to a "critical segment"
analysis, (p-36, lines 4-6) '
Staff Response - See response to comment 64.
97. Department of Energy
This same caveat applies also to all other calculations of dose
from 244cm in this Guidance and should be discussed in connection
with these other calculations, (p-36, lines 12-14)
Staff Response - Agreed.
98. Department of Energy
Pertinent animal data on leukemia risk from transuranics is
ignored, (p-37, Section 3.9.1)
Staff Response - Pertinent animal data on leukemia from
transuranics was not ignored. It is summarized in Reference 51 by Dr.
Vaughan. However, the application of animal data on radiation-related
leukemia has been summarized by UNSCEAR-1977 as follows, "In view of
the diversity of these syndromes myeloproliferative and
lymphoproliterative diseases and in the absence of any indication as
to whether and to what extent any of them might be akin to human
leukemias, attempts to identify the nature and the number of cells at
risk on the basis of our present knowledge may only be regarded as an
'academic pursuit1."
99. Jefferson Country Health Department
Leukemia due to bone marrow irradiation (page 37). The report
states that for a three millirad limiting dose to bone marrow, the
leukemia risk ranges from 0.4 to 1.6 cases per 100,000 exposed, for
the absolute and relative risk models, respectively. This is
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; 48
apparently based on the fact that the leukemia mortality due to excess
radiation is .about 1/5 of all radiation-induced cancers. This
estimate is considerably less than my own and seems not to be a
conservative estimate (4). (p-37) : f
Staff Response - No. Effects from to1:al body irradiation were
estimated from the leukemia risk, not the other way around. However,
the leukemia risk estimates in Annex III contain a computational
error. Revised risk estimates for leukemia are presented in Section
6.1. .
There is also a typographical error on page 37, Annex III, line
24. The sentence "For a 3 mrad limiting dose to have,in the 70th
year,...",should read "For a 3 mrad limiting dose to bone in the 70th
year,..."
100. Department of Energy
There is no basis given for the suggestion that "7% of actinides
(are) distributed in the body tissue after inhalation;" such a
statement should be referenced. The argument of the paragraph seems
specious, since a total body transuranic dose has.no meaning, and the
"early deaths due to leukemia indicated in Table A 3-17" were not
based upon total body plutonium. (p-38, lines 3-11),
Staff Response - Further information on the derivation of the
estimate of 7% of actinides distributed in soft tissues is given in
Reference (1) in Annex III.
The basic rationale is that ICRP-19 estimates that 10% of '.,...
plutonium (or other actinide) transferred to blood is deposited in
soft tissue and,excreta. From Durbin's reports on plutonium
distribution in, man (P. W. Du,rbin, pp. 469-530. in Radiobiology of
Plutonium, 1972; P. W. Durbin and N. .Jeung pp. 297-313 in The Health
Effects of Plutonium and Radium, 1976); the distribution of injected,
plutonium in animal tissues other than skeleton and liver, is about
15.5? and in excreta 6.1%, i.e., a ratio of, activity in soft tissue to
that in excreta that is approximately 70% to 30%. That 7% of blood
plutonium is in soft tissue is a reasonable estimate, is supported by
Mclnroy's observation that in tissues of occupationally-exposed ,
individuals, the total body burden is distributed as follows:
Lung
Skeleton
Liver
Trachepbronchial
, Lymph Nodes
Other Soft Tissue
28.2% ± 22.6%
47.5% ± 29.3%
18.1% ± 15.3%
, 4.7%'_.+' , 4.6%
7'.0% ± lo.9%
(J. F. Mclnroy,
Radium, 1976).
pp. 249-270 in The Health Effects of Plutonium and
1.47
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49
101. Department of Energy
It is not stated how the "estimated range of between 3 and 30
early deaths" is arrived at, but it presumably derives from the
highest and lowest values of the four different BEIR models, in which
case it is not a range of risk, but simply the range of different
estimates, each of which have a very large (and basically
unquantifiable) uncertainty. The statement is misleading since it
implies that at least three deaths will occur in the cohort of 100,000.
(p-38, lines 16-18)
Staff Response - The Agency agrees with the first part of this
comment. The range indicated is simply the range of different
estimates, each of which have a large uncertainty.
The Agency does not believe the statement concerning either the
minimum or maximum risk to be misleading. As a best judgment based on
current knowledge, the Agency does not believe that the uncertainty in
risks can be substituted for a postulated threshold so as to presume
zero effects for finite doses.
102. Department of Defense
Footnote is not tied to table, no reference for table which is
true for many of the tables in this annex, (p-49, Table A 3-5)
Staff Response - All comments on table are largely correct but
editorial in nature.
103. Jefferson County Health Department
On page thirty-eight (summary of health risks) the report
estimates that the total somatic and genetic risks due to inhalation
of transuranium element aerosols causing an annual dose to the
pulmonary region of one millirad per year (20 millirem per year). The
estimated cancer risk to one million people is 90 premature deaths,
with an estimated range of 30 to 300. An annual dose to the pulmonary
region of one millirad per year is roughly equivalent to 20 millirem
per year to the lung, 960 millirem per year to tracheobronchial lymph
nodes, 60 millirem to bone, about 30 millirem to liver, 4 millirem to
kidney and one millirem to gonads. In my opinion, this dosage would
result in about 110 excess deaths due to leukemia and a total increase
in all neoplasms of perhaps 1 to 2% over a period of seventy years.
The incidence of all genetic diseases could increase by 1% and ill
health related to chromosome mutation by about 7% for all succeeding
generations from this dosage level.
148
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50
Staff Response - The commentor has errored in his interpretation
and use of the 1972 BEIR Report, see response to comment 21 submitted
by the same commentor. -~-'-f: •••- * '
104. Department of Energy ,
"Genetic Risk" requires definition in terms of the kind(s) of
effects the numbers refer .to. Without further definition they might
be interpreted, erroneously, as "premature deaths".
(p-62, Table A 3-18)
Staff Response - The genetic risk estimates referred to are those
characterized as "Serious Disabilities" pages 55 and 56 of the 1972
BEIR Report. These include: dominant diseases, e^g., Cowden's disease
or Von Recklinghausen's disease; congenital abnormalities, and such
constitutional and degenerative diseases as anemia, diabetes,
schizophrenia and epilepsy, but not heart disease, cancer,,or ulcers.
105. Department of Energy
The "range" column is misleading. It should.be clearly indicated
that these are not ranges in the, usual sense of upper and lower
limits, or the result of some statistical measurement, but are simply
the highest and lowest of the numbers derived from different models.
(p-62)
Staff Response - See reply to comment 101.
106. National Council on Radiation Protection and Measurement
The dose rate calculations are performed assuming a constant
infake over alifetime. This may apply to the effluent from a
processing plant and to ?39pu £n soils but not for the other
nuclides in soils because of their relatively short half-liv£s.
We recommend the inclusion.of tables for the nuclides that take
into account the decrease in soil concentration with time due to
radioactive decay.
Staff Response - See response to comment 57. Changes inactivity
level must be considered on a site-specific basis since radioactive'
decay is only one factor. Transport of contaminating material into or
out of the local biosphere may be more important.
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51
107. Ilene Youngheim
I do not understand your terms Relative and Absolute in regard to
risk, such as Table A 3-10. I can understand the absolute premature
deaths being less than the relative premature deaths, but why would r
the average years of life lost to premature deaths be less (for ;
relative risk), 18.4, than for absolute risk, 22.0.
Staff Response - Relative and Absolute refer .to the form of the
assumption underlying the projected numbers, of expected cancer
deaths. The question addresses the measures of the lifetime health
risk due to lung cancer mortality induced by pulmonary doses.
The absolute -risk estimates assume that the incremental lung
cancer mortality resulting from exposure to transuranium elements
increases in direct proportion to the dose, and is independent of the
natural incidence of lung cancer. The relative risk estimates assume
that incremental increases are related to both the level of exposure
and to the natural incidence rate for lung cancer in the U.S.
population (i.e., risk is proportional to the product of the exposure
level and the natural lung cancer mortality rate). The use of
relative risk models implies that radiation interacts with other
factors that contribute to the natural incidence of cancer.
The differences in the average years of life lost to premature
deaths assuming relative and absolute risk is a result ,of difference
in the age distributions of the projected lung cancer deaths. U.S. •
mortality statistics show that lung cancer is a cancer of old age,,
hence fewer years of life lost per cancer death jare predicted in
relative risk calculations. ;''...
108. Ilene Youngheim .. ,
t ' '• - j ..-•-,,
Annex 3, 3.1. It is possible that your estimation of effects on
gonads has been underestimated. Plutonium has concentrated in the
gonads of animals pasturing close to the Rocky Flats Plant.
Staff Response - The Agency staff believes that its evaluation,of
genetic effects in humans resulting from plutonium inhalation or
ingestion accurately reflects the viewpoints of experts in this
field. The presence of plutonium in the gonads of cattle grazing on
contaminated soils is expected, but is not necessarily comparable to
uptake and distribution by humans.
109. Jefferson County Health Department
The report states (page 34) "for reasons given below, genetic
damage from alpha particles is expected to be about a factor of 100
greater than that assumed in the BEIR Report. Based on current
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'••••^ -52 . ' •' • ^ '
recommendations of the ICRP, alpha particles are 20 times more
damaging than x-irradiation for a number of biological endpoints,
including genetic effects. This is not necessarily over^-conservative,
since an increase of about 20 compared to-x-irradiation has been
reported for genetic damage from highly ionizing neutron
irradiation." In additiony there is some opinion that the 1972 BEIR
Report may have underestimated the amount of multifactorial diseases
having a genetic component. However, despite these conservative
assumptions on page 30, the report estimates that a 30 year dose of
one millirad from alpha-emitting transuranium elements, in genital
tissue may cause only between 0.1 and two genetic defects per 100,000
live births in the first generation, with a potential in later
generations of 0.6 - 15 -defects per 100,000 live births. This figure
seems to be inconsistent with estimates of risk to health posed by
four .millirem of iradionuclides in the support document for the EPA
Water Quality Regulations. •
Staff Response - The basis for the genetic risk estimates is
given in Annex III of "Proposed Guidance on Dose Limits for Persons
Exposed to Transuranium Elements in the General Environment." Similar
estimates for genetic risk were presented in the support document for
the EPA Drinking Water Regulations, EPA-570/9-76-003.
110. Jefferson County Health Department ;,
On page twenty two the report cites a1 1976 National Academy of1
Sciences Report which states that the absolute risk (the number_of
cases that will result from exposure of a given population) estimate
for bronchialfcancer in uranium miners is 20 cases per million
organ-rad per year at risk, and not 10 as indicated in the 1972 BEIR
Report. The number of lung cancers from alpha radiation at a given
dose appears to be increasing as the years at risk in relevant
epidemiological studies are extended. The relative risk estimate (the
ratio of the risk in those1 exposed to the' risk to those not exposed)
in the 1972 BEIR Report also is likely to be low. "Assuming that the
relative risk for U.S. miners is increased an a manner 'similar to the
absolute risk, it would be comparable to the 1972 BEIR estimate for
Canadian miners who have been similarly'exposed." That is a 6%
increase in annual incidence per rad. The 1972 BEIR Report assumes ia
15-year latent peribd (10-20 years) for all solid tumors induced in
both children and adults. '
Staff Response - The staff agrees.
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3.4 Annex IV - Risk Perspective
1- Department of Energy
A more specific reference would be helpful. (p-1, iines 8-9)
Staff Response - The reference is to the brief description of the
general characteristics of the life table methodology. A more
methodol°8y " available. (See
2. Department of Energy
"Cohort" should be defined. (p-1, line 14)
.S*;fff,?ersP?nse ~ A cohort is a group of individuals of common
age. _Tne lifetime mortality experiences of cohorts of 100 000
individuals are used in this analysis.
3« Department of Defense
This section indicates that EPA has developed its own
methodology, which is unavailable, but which may be changed. This
precludes any reasonable attempt to evaluate its validity and in
effect, is an unacceptable situation. (p-1, Section 2)
Staff Response - EPA did not intend that the discussion of the
5! frV?1 methodol°8y would give the reader the impression
tne liS ?eM f ,Tld *S Changed in the future' A Ascription of
*nH M ? « * met*odol°8y " available. See J.R.Cook, B.M. Hunger,
and M.K Barrick, "A Computer Code for Cohort Analysis of Increased
Risks of Death", EPA 520/4-78-012, USEPA, Washington, D?C. (1978)
4. Department of Energy
referred *? "^ ^Z™ **? ' °* Wh°Se' "method°l°8ical differences" are
referred to, or why. The sentence is confusing. (p-2, lines 14-16)
Staff Response - There is a difference in methodology between
removing a risk from the life table and adding a risk to it.
5. Department of Energy
Methodol<)8y referenced, as TO11 as the methodolouy
in order t
Staff Response - See response to Comment 3.
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6. Jefferson County Health Department
The purpose of this annex is to make the excess death rates due
to exposure to radiation appear more acceptable by comparing^them with
death rates from diseases and accidents presently experienced by the
U S population. The effects of radiation are further compared to
effects from background radiation received by the U.S. population
about 100 millirem to the whole body. The implication given is that
if a person is receiving radiation of the same order or less than the
background radiation he is already receiving, that the additional
increment is not really significant. This is not really the case,
since it is felt that background radiation itself produces an ettect
on the population in terms of an increased rate of cancer and genetic
defects. Adverse effects should not be considered more acceptable
merely because there are other adverse effects to which we are exposed.
(p-4, Section 3)
Staff Response - The purpose of this Annex is to provide
information relevant to an evaluation by the reader of the
acceptability of the limiting risk for the guidance recommendations.
It clearly does not make the judgment of what constitutes an
acceptable risk level, nor does it argue that an additional increment
of risk is not significant.
7. Department of Energy
Since there is no table identified as Table A 4-1 in this Annex,
presumably Table IV-1 is intended. (Similar comment applies to page .
IV-5, lines 4 and 10, and page IV-7,- lines 10 and 14.) (P-4, line 23)
Department of Defense
Table designation does not conform to that of the table (A 4-1 vs
IV-1). Same applies to other tables. (p-4, line 23)
Staff Response - All references to tables in Annex IV should have
been designated with the prefix IV instead of 4.
8. Department of Energy
Cautionary statements concerning the limitations of BEIR risk
estimates are needed and should appear at this point.
(p-4, lines 24-25)
Staff Response - The BEIR report is well known and accepted in
the radiation protection field. We do not believe that cautionary
statements concerning the limitations of the ,BEIR risk estimates are
warranted.
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9. Ilene Younghein
Annex 4, p.6 "Exposure to 1 mrad per year is therefore estimated
to have a much smaller lifetime impact than does background
radiation." I should hope so! If death rates, life shortening, and
gentic^damage become as prevalent from plutonium as from background
radiation, we would really be in sad shape. There is one vital
difference though. We are stuck with background radiation, it is a
risk we can do almost nothing about. The risk from plutonium is a
risk that we have added on to the risk from background. It probably
is erroneous to talk of life shortening and premature deaths in terms
of background radiation. They are part of the basic formula at
birth. Better to talk of life lengthening if we could devise a way of
doing without it. (p-6)
Staff Response - We agree. The purpose of the guidance is to
minimize the risk to persons in the general population from exposure
to a single potential radiation source. The recommended risk is well
below that from background radiation. Numerical values are given to
provide a perspective.
10. Department of Defense
It is not surprising that the life shortening is approximately
the same for both forms of risk because the calculational method
employed was the same. The point is missed by this reader, (p-7
line 7)
Department of Energy
That "the life shortening is approximately the same for both
forms of risk" would be expected because it was calculated the same
way for both, (p-7, lines 7-8)
Staff Response - The comment is incorrect. The life table method
takes into account the age distribution at time of death. Since the
dose to various organs from inhaled and ingested transuranium elements
is highly time dependent, it can be expected that the age distribution
at death, for organ specific causes of death, will differ for each
organ. Therefore, predicted life shortening for different types of
exposure (background radiation, inhalation and ingested transuranium
elements) is not expected to be the same for all cases analyzed by the
life table method.
11. Department of Energy
The relevance of this material is not established.
(p-7, section 4)
154
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Staff Response - Section 4 addresses the comparison of other
forms of risks of death generally experienced by members of the
population to the risk from exposure to transuranium elements.
f r*
55
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3.5 Annex V - Guidance Implementation
1• Department of Defense
^ mile the Agency may believe "that these recommendations can be
implemented...without requiring...unreasonable, unnecessary, and
expensive regulatory actions," the analyses required to show that this
is true have not been done. Such a statement should be referenced tou
a study or studies showing this to be a fact. (p-2, lines 1-3)
Department of Energy
There is a great disparity between the EPA's belief that the
recommendations can be implemented without requiring unreasonable
unnecessary and expensive regulatory actions and the actual case of
implementing. Certainly the supporting material has not presented a
convincing case that implementation would not be expensive. This is a
prime example of taking liberties between fact and supposition
(p-2, lines 2) '
Nuclear Regulatory Commission
The conclusion that the proposed guidance would be capable of
implementation at reasonable cost to licensees is not adequately
supported by the information provided in the EPA Technical Summary
Document. Further, the statement in the Federal Register Notice that
the Guidance is capable of implementation at reasonable cost is in
conflict with the earlier statement, in Rationale for Guidance, that
EPA has found that costs of remedial actions will differ so greatly
between contaminated sites that generic cost-benefit .guidance cannot
be provided. More discussion should be presented to support the
conclusion that the cost of implementing the guidance at the reference
level of soil contamination is, in a generic sense, reasonable.
Staff Response - The agency staff has evaluated the status for
all existing sites of known transuranium element contamination in the
United States, and has concluded that it is very unlikely that
large-scale remedial actions will be required to ensure compliance
with the guidance recommendations. Therefore, regardless of the'cost
of remedial actions per unit area, the total cost of implementation
for existing sites is judged to be reasonable and achievable. In view
of the above, and the alternatives available to the implementing
agency, the agency staff staff believes that the statement is fully
valid. J
^ Costs of remedial actions for sites which may become contaminated
in the future are considered in Sections 4 and 5.
156
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2. Department of Energy
* In the area of administrative implementation, there is a lack,of
unambiguous definition of the choices permitted, and the circumstances
under which they are permitted. Three general procedures for
implementing the Guidance are set forth on p. 2 of Annex V, but one of
these is identified as the "preferred method," which could make it
administratively very difficult to choose any other. Actually, there
can be no predetermined preferred method, since the preference will
depend upon the site-specific information obtainable and cost-benefit
considerations.
Method "a" may not be the "preferred" method. Preference is
determined by the information obtainable and cost-benefit
considerations.. To label one method as "preferred" will make it
administratively very difficult to employ any other method.
(p-2, line 10).
Staff Response - The intent of the Agency is to maintain
flexibility in implementation of the Guidance. Methods which
introduce the.cost ambiguity are generally to be preferred, consistent
with the site-specific information available, necessary time
constraints, and other similar factors. The agency staff staff
believes that public acceptance of any administrative decision is
largely determined by a full and complete disclosure of all
information and that, on a technical basis, any of the proposed
methods provides an acceptable implementation procedure.
3. Department of Energy
Where flexibility is not permitted, requirements should be
precisely stated; where flexibility is permitted, advice must be
carefully worded to avoid compromising the intended flexibility.
proposed Guidance is notably deficient in this critical area.
The
EPA should either leave this choice entirely to the agencies
having regulatory and administrative responsibilities for the site in
question, or specify which of these clearly defined procedures should
be employed for each of several categories of clearly defined
incidents; this would reduce the flexibility but simplify the
administration.
For example, soil sampling to a depth of one centimeter is
specified, though the sampling of any reasonably sized area to this
depth is virtually impossible under field conditions; sampling and
preparation of soil samples should employ "a method which does not
cause the breaking up of soil aggregates," but it is. doubtful if such
a method exists; and acceptable maximum chance of a wrong decision in
evaluating soil contamination levels is suggested to be 5-10%,
157
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although there is no assurance that such precision is possible under
any reasonable circumstances; air sampling programs should "ensure
that air concentration levels are representative of actual exposure
conditions, but no such sampling procedures exist; all methods
employed must "have the necessary sensitivity, accuracy, and precision
for purposes of implementing this guidance," but the necessary
sensitivity, accuracy and precision are nowhere defined.
Staff Response - The agency staff believes that some uniformity
of approach is essential for proper interpretation of the results. :
For that reason, generalized sampling and analysis procedures are
suggested which can be expected to give results appropriate for use in
the decision making process. Such generalized procedures obviously
must be adapted to local conditions, and it is the responsibility of
the responsible Federal agency to choose procedures which will best
satisfy the implementation criteria of the Guidance It is
acknowledged that precise adherence to the suggested procedures may be
impracticable or even impossible, but these procedures should at least
form the basis of a program of evaluation and major deviations should
be justified.
The staff does not agree that sampling to a depth of about one
centimeter is impossible for most types of terrain, and believes that
soil preparation methods do exist which do not greatly change the
physical characteristics of aggregates. Statistical sampling
techniques are generally designed with a defined objective of accuracy
and precision, and the frequency of sampling is determined
accordingly. The time and resources required to achieve a 90-95%
confidence level may sometimes be unreasonable, but deviations from
this objective should be justified. The staff also believes that air
sampling programs currently in use at several existing sites meet the
specified criteria, and do satisfactorily measure annual average
ambient air concentrations. The "necessary sensitivity, accuracy, and
precision of analysis techniques represents a judgment situation and
is ultimately closely related to the overall confidence level required.
4. Department of Energy
If these procedures are available they should be referenced. The
available procedures are largely concerned with the evaluation of
population averages and are not appropriate to consideration of the
"critical segment." (p-5, lines 2-6)
Staff Response - The statement refers specifically only to
measurement, and not to calculation! procedures. Application of the
guidance recommendations to a "critical segment of the population" may
require knowledge of site-specific population or land use
characteristics.
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5. Department of Energy .
1 •'- ~ ' . *- -_ :. ^*' _ _-_. "'' ' "' - ' ,•' ' '
It' is not clear what this sentence is trying to say, but the
several reasonable possibilities all seem to be incorrect. It
provides little guidance unless "in close proximity to" is given more
specific definition. (p~8, lines 8-11)
Staff Response - The intended, meaning .is that the particulate
content of air is mostly derived from surface materials located at .
some distance from the point of measurement, and only a small fraction
is that resuspended from the immediately adjacent area.
6. Department of Energy
If there is a method "which does not cause the breaking up of.
soil aggregates" it should be referenced. (p-12, lines 9-11)
Staff Response - The intended meaning is to avoid, deliberate
breakup of aggregates by milling or grinding in those samples
designated for particle size analyses.
7. Department of Energy ....••. .
A single reference seems inadequate, for this entire subject.,
(p-12 lines 13-20)
Staff Response - A more detailed discussion of Guidance
implementation is provided in Section 5.
8. Department of Energy . - , -
The statement that a 5-10% maximum chance of error is "generally
considered appropriate" leaves one uncertain,as to whether EPA .will
consider this an appropriate criterion. If this is, in fact, the
criterion, it is a very important part of the Guidance and requires
further discussion. (p-14, lines 12-14)
Staff Response - The staff believes that a 90-95% confidence
level generally represents a realistic objective for environmental
measurements. We do not think that further discussion is required.
9. Department of Energy
For how long is "stabilization" considered effective?
(p-16, lines 7-12)
Staff Response - Stabilization is a temporary measure, designed,
to prevent dispersion during the initial phase after deposition when
the material is most mobile.
159
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10. Department of Energy
It seems inappropriate that an Annex on implementation includes
only four references, two of which are not referred to in the text.
Staff Response - The comment seems to misinterpret the intent of
this Annex. The staff believes that the implementing Federal agency
has primary responsibility for evaluating the situation and for
choosing the appropriate remedial actions. The principal purpose of
this Annex is not to provide a technical implementation manual, but
rather to give sufficient information to members of the general public
to let them judge the feasibility (and problems) of implementation.
11. Department of Defense
"Much greater or much smaller" has no precise meaning and is
therefore useless, (p-3, line 19)
Staff Response - The terms are relative and interpretation is at
the discretion of the implementing agency.
12. Department of Defense
Reference the procedures and indicate their acceptability for use
in compliance, (p-5, line 2)
Staff Response - See response to comment 10.
13. Department of Defense
This entire Annex is so vague and contradictory that it is
essentially useless. It can only result in controversy, confusion and
possible litigation. Several examples illustrate this:
(a) Page 14, line 21: In effect, it says you can choose a
statistical method to give the results desired.
(b) Page 11: Says ingest ion of dirt may need consideration
because of importance, but in Annex II, this route is considered of no
importance.
Staff Response - The staff does not agree that Annex V is vague
and contradictory, and believes that it serves its intended purpose
(a) The paragraph referred to says that, where acceptability of an
area is in doubt, decisions are best based on statistical tests, (b)
The sentence in entirety reads "the more unusual transfer methods to
people .... may need to be examined if shown to be of importance."
160
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14. Jefferson County Health Department
: On page 5, emphasis is placed on the annual average transuranium
element concentration in air. However, air sampling devices may not
provide an accurate estimation of the potential risk to residents of
areas contaminated .with plutonium,
Staff Response - The staff believes that the annual average
concentration of transuranium elements in air is the best indicator of
the inhalation hazard to persons from chronic exposure. The accuracy
of measurements will need to be evaluated for each specific occurrence.
15. Jefferson County Health Department
In the last paragraph on page 9, the Agency again appears to
support the use of resuspension factors, which were reported earlier
to have a variability of as much as one million. The use of such a
factor, it seems to me, is very questionable.
The guidelines recommend that soil samples should be taken to a
depth of one centimeter and the transuranium element activity measured
in the particles less than two millimeters in size. This^sample, as I
have pointed out previously, is inappropriate for evaluation of a
respirable dust hazard. In addition, I do not feel, as the Agency
does, that samples may be composited for a single measurement. If
this is done, hot spots will be undetected when averaged with many
other locations with lower levels of activity. I find these
guidelines to be unacceptable. The best way to evaluate a hazard from
airborne contaminated dust is by use of respirable dust sample from
the surface of the soil.
Staff Response - (a) The staff does not specifically support use
of a resuspension factor, and recommends that the relationship between
soil and air concentration be determined by use of the mass-loading
calculational method, (b) The staff does not support the use of Dr.
Johnson's "respirable dust" sampling method and believes it to be
inappropriate for.implementation of this Guidance (see Section 7).
(c) Compositing of several samples for chemical analysis is a .
generally used and accepted technique. "Hot spots" are of^importance
only to the extent that they change the uptake by an individual.
16. Jefferson County Health Department
On page 12, the report mentions "the usual method for determining
distribution of soil particle sizes is by sedimentation analysis" and
then cautions that "soil characteristics should be altered as little
as possible in the collection and preparation of the soil sample, and
care should be taken to choose a method which does not cause the
breaking up of soil aggregates that were present when the sample was
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taken." This statement appears very strange when we consider that the
alternate method used by the EPA, Rocky Flats and the Colorado State
Health Department involves the use of agricultural soil samples which
are dried and pulverized to a fine powder in a steel ball mill.
Staff Response - The comment apparently confuses two entirely
different aspects of the evaluation, namely size distribution of
particles and chemical analysis of the soil samples. Retention of
soil physical characteristics is essential only for.the determination
of the particle size distribution, while reduction to a fine power is
a preliminary step in the chemical analysis procedure.
17. Department of Energy
It has not been shown that "most of the potential hazard is
derived from contamination at, or near, the surface." This depends
upon the depths of the disturbances possible in the area. The
contention that "most man-made disturbance will reduce the
concentration in the top layer" may not be true if levels higher than
those permitted by the Guidance have been reduced by mixing through
the top layers. In such a case, further disturbance will gain nothing.
(p-4)
*
Staff Response - We agree with this comment but would point out
that the conclusion is applicable only to the choice of remedial
actions and does not change the rationale for the Guidance.
18. Department of Energy
A major ambiguity surrounds the administrative aspects of
determining and certifying compliance with the Guidance. It is
implied that reports must be made, but never stated to whom. It is
recommended that remedial action be taken quickly, but requirements
for environmental impact assessment, evaluation of area contaminated
to a precision, of 5-10%, sampling of air at weekly intervals, sampling
food, etc., will,preclude quick action.
Department of Energy
To whom do the Federal agencies "certify that Guidance
values«..are not being exceeded?" At what level above background is
such certifipation required? In other words, what triggers this
procedure? (p-4, lines 11-14)
This paragraph discusses vaguely defined requirements, with no
indication of which entity will be responsible for those , '
requirements. A definition of reports required, and to whom they
should go, is not discussed in this Guidance, (p-11, lines 7-13)
162
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Department .of Defense
To whom do the Federal agencies certify that 'guidance values are
not being exceeded? What is the process, time requirements,
administrative procedures, etc.? It is not made clear here or
elsewhere. (p-4) ,
Staff Response - No reporting requirements for this Guidance
exist at present, but the Agency may establish such -requirements at a
future date. .
It is not the intent of the Guidance to require administrative
procedures that would preclude prompt remedial actions in the event of
a contaminating event. . ,. .
19. Department of Energy ...
This .sentence seems "to assume that there is a particle size
distribution characteristics of a specific site. Actually this
distribution will vary'with wind speed, soil moisture, dust brought
from off-site, mechanical disturbance, etc. To obtain any realistic
measure is a very long and expensive procedure. It is not clear that
such intensive study, which can only be performed at a few points,
would be cost-effective. (p-5,"lines 12-13) -
Staff Response - We agree 'that the sentence is ambiguous. 'It is
intended that the implementing agency use site-specific data to the
maximum extent practicable, without going to the extreme of a
long-term research effort. .
20. Department of Energy
This sentence is unrealistic. Many current studies are
indicating the complexity of environmental solubility considerations.
Predictions in this area are extremely uncertain. In any case, the -
only guidance given in Annex III is for Class Y compounds.
(p-5, lines 15-20)
Staff Response - We disagree with the conclusion that the
sentence is entirely unrealistic, at least to the extent that the
solubility class of most transuranium elements in the environment can
be inferred from their history or other data. Hov/ever, the comment is
correct in that major uncertanties do exist and it cannot a priori' be
assumed that Class Y (insoluble) is applicable in all cases. A
discussion of the changes introduced by Class W (soluble) compounds is
given in Section 6. . ' . ' ;
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21. Department of Energy
Sentence is more intelligible if "into" is changed to "in."
However, the relationship implied in the sentence is not established.
(p-7, lines 5-7) ^
Staff Response - The reference is to the greater availability of
transuranium elements biologically incorporated into plants or animals
(See Annex III)
22. Department of Energy :
Perhaps the most serious ambiguity is that surrounding use of the
soil screening level. Its use is appropriately recommended in the
Summary Report (p. 29) as a procedure that "can serve to reduce the
land area requiring evaluation and minimize the number of measurements
needed." In Annex II (p. 25) it is stated that the screening level
"will identify land areas where no additional monitoring is
required." But in discussion of the soil screening level in Annex V
(p. 9) it is stated that "In all cases the cumulative doses to the
critical segment of the population must be considered," which will
require the complete characterization of the contaminated area that
the soil screening level was designed to avoid. Again, in Annex VI
(p. 11), it is stated that in the off-site areas adjacent to the Rocky
Flats plant, "more intensive evaluation may be needed to determine the
actual dose rates to the general population," this despite the fact
that the soil screening level is not exceeded (as indicated on p.
10). In Annex V (p. 8) it is stated that "the screening level concept
may not be applicable when the soils of a contaminated area contain
these^nuclides (Am and Cm) in amounts greater than 20% of the total
activity." The potentially very useful concept of a soil screening
level has thus been compromised by vague references regarding its
inapplicability under various circumstances, to the .point that it is
doubtful whether its use could ever be justified.
It is suggested in this paragraph that a conservative "derived
air concentration limit" be employed as a test of compliance, when
other approaches are "difficult or impossible." If a simple cheap
comparison to an air "screening level" is possible, why go to the
expense of unnecessary site-specific evaluation. This is the
expressed philosophy on which the soil screening level is based. It
would seem that the "air screening level" should be similarly
considered and included along with the soil screening level in the
Summary Report. (p-15, line 21)
This says that in all cases you must do everything, which
contradicts the philosophy of screening levels. (p-9, line 9)
It is stated that "the screening level concept may not be
applicable." (p-8, lines 12-17)
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Staff Response - The intent of the ''screening level" is as
stated, name1y to exc1ude from detailed evaluation those areas where
contamination is sufficiently low so that there is little possibility
that resultant doses to persons would exceed the guidance
recommendations. This judgment is based on calculations which have
considered both the inhalation and ingestion pathways, but which may
not have included some very exceptional circumstances.- The presence
of "more than 20 percent of the total activity as americium or curium,
which are more soluble and therefore represent a greater ingestion •
hazard, is such an exception. Therefore, the staff believes that the
admonition to consider such exceptions, where warranted, is both valid
and indicated.
The air screening level provides assurance only that Guidance
levels are not exceeded through the inhalation "pathway. The use of
such an air screening level is not precluded by the Guidance
implementation procedures.
23. Department of Energy '
The "derived air concentration limit" must be based on singularly
defined parameters. The specified AMAD is presumably 0.1 urn. The
phrase "not to exceed" therefore seems inappropriate. While
conservatism is perhaps justified in the derivation of such a
"screening limit," the unrealistic AMAD of 0.1 urn would seem to be
excessively conservative. (p-6,:lines 2-6)
Staff Response - An AMAD of 0.1 micrometer may be used if
measured values are not made for the specific site under
consideration. We do not believe this value to be excessively
conservative because the difference in dose calculated using an AMAD
of 0.1, micrometers compared to the more "realistic" value of 0.5
micrometers is only a factor of 2.
24. Department of Energy
"Disturbed sites" are not addressed. These are part of the
exposure potential and should not be overlooked. (p-11, lines 15-19)
Staff Response - The "disturbed site" was addressed in .the
derivation of the soil screening level (Annex II)
25. Nuclear Regulatory Commission
The alternative remedial action of establishing restricted access
or use of the area in question is not discussed in the federal
Guidance. We propose that, at least for future contaminating events,
the guidance state that this alternative not be used, if at all
possible.
165
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11
Staff Response - Remedial action choices are the responsibility
of the implementing agency. However, we agree that it is preferable
to clean up a future contaminating event and that simply establishing
restricted access should not be used if at all possible.
26. Nuclear Regulatory Commission
We are concerned that the proposed reference level of soil
contamination which is presented in the statement of consideration as
a screening level, "based on limited data available for several
existing sites," may be interpreted as an effective action level.
Discussion of the reference level in the presentation of the modeling
methodology used in the backup document appears to be sufficient.
Staff Response - We agree.that the screening level should not be
considered an effective action level.
27. Nuclear Regulatory Commission
In order to clarify that the operative guidance for newly
contaminated areas are the dose rates specified in paragraph one of
the text of Proposed Guidance, we recommend that the second sentence
of paragraph two be deleted.
Staff Response - We disagree. The intent of the second sentence
is to make it clear that not only is the dose to be minimized but that
remedial actions are to continue until doses are projected to be well
below the guidance levels. It is not likely to be possible to verify
compliance within a time frame comparable with the time needed for the
remedial action. A degree of conservatism is justified.
28. National Council on Radiation Protection and Measurements
We recommend that the actions following a future possible
accident be better defined and that a study be made to show that these
limits are appropriate.
We recommend that this Annex be rewritten with careful
consideration of the practicality and cost of the requirements and,
that a specific section on implementation following accidents be
included.
Staff Response - Comments on the proposed guidance have supplied
valuable additional information on the potential costs and
effectiveness of remedial actions for possible future contaminating
events. These are discussed in Section 4 and 5 and the Agency has
concluded that the Guidance is appropriate for future contaminating
events.
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12
29. Jefferson County Health Department, • • *.. .'--'•
This screening level value is not conservative, and does not
provide adequate protection to the public. In my opinion, residents
of areas with this degree of contamination will be unwilling to accept
the effects of such exposure.
Staff Response - We disagree. In our opinion the screening level
is conservative.There is no evidence that residents of areas
contaminated to levels below the screening level will be unwilling to
accept the very small potential risks.
30. Jefferson County Health Department
The report notes that the choice of suitable methods for sampling
and analysis is the responsibility of the agency implementingthe
guidance. In the case of the area around Rocky Flats, there may be
several such agencies involved in this implementation, i.e. j the
Health and Safety Laboratory of the Department of Energy, the State
Health Department, and the Jefferson County Health Department. It
would be desirable for the agencies to agree on a standardized
approach. - . . s
Staff Response - We agree.
31. National Council on Radiation Protection and Measurement:
The Implementatipn Annex provides a number of general statements
as to methods of assuring that the guidance is met. A number of these
appear to differ from similar statements in other Annexes and the
general impression left is one of confusion as to what should be done
and how well. There is no specific implementation for accidental
releases so that one can only conclude that the entire Annex will
apply- _ . ,.'-'-.-. ,x ; •_
We recommend that this Annex be rewritten with careful
consideration of the practicality and cost of the requirements and
that a specific section on implementation following accidents be
included; ' '
Staff Response - Annex V is intended to provide generalized
guidance on methods appropriate for assuring compliance with
recommendations. In the absence of more specific information on where
conflicting advice is given, no answer can be provided on this comment.
Evaluation of the consequences of possible accidents, and of the;
need for remedial actions, should follow the same general procedures'
as outlined in this Annex. However, time constraints on initiating
actions are expected to be more stringent for instances of new
contamination.
1C?
-------
13
32. Department of Energy
To avoid lengthy future contention over what this Guidance does,
or does not mean, it is recommended that the entire document be
carefully reviewed to eliminate Inconsistencies and ambiguities; and
that Annex V be rewritten in a clear and simple fashion, being careful
to recommend only those procedures whose applicability has been
demonstrated, and to avoid comment on procedures that are left to the
discretion of the Agency implementing the Guidance.
Staff Response - Refer to comment 31.
33. Department of Defense
The intent and impact of this sentence appears ambiguous, while
"unnecessary cost" may be avoided, the
large. (p-2, lines 20-23)
"necessary" cost may be very
This is a misleading oversimplification of the proper objective
unless it is made clear that "cost" includes such items as dislocation
of people, environmental damage and other non-monetary costs. The
mention of non-monetary costs earlier in the paragraph is not adequate
to prevent this misinterpretation. (p-15, lines 17-20)
The very important non-monetary costs considered in these
paragraphs should not only be considered in deciding between
alternative cleanup procedures, but should be balanced against the
risks of no remedial action at all. (p-18, lines 13-21)
These psychological costs, which receive only passing comment in
the last sentence of this Annex, must be considered to be a serious
risk involved in transuranic contamination of the environment. Many
of the actions that might be taken to reduce other risks may increase
the fear that leads to these psychological costs. (p-18, lines 20-21)
Staff Response - Economic considerations are described in
Section 4. Non-monetary and psychological costs are difficult to
quantify.
34. Nuclear Regulatory Commission
It appears that the costs of taking remedial action for
facilities licensed by this Agency would substantially exceed the
lower limit value of $500 per acre assumed for the proposed guidance.
For example, disposal of surface soils by burial in commercial
low-level waste burial sites would probably equal or exceed the costs
of the general per cubic foot charge for burial. Using a value of $3
per cubic foot (NUREG-0217) would result in an estimated cost of $5000
per acre for burial charges alone.
168
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14
Some NRC licensed facilities are located in areas having other
buildings and structures which would be substantially more costly to
decontaminate than for a facility located in a remote area. A recent
"Draft Engineering Evaluation of the Latty Avenue Site, Hazlewood,
Missouri," by Ford, Bacon, and Davis, Utah, Inc., dated January 1978,
indicates that the five remedial action alternatives evaluated for the
18,300 cubic yards of contaminated material at the 10 acre site, range
from $457,000 for cleanup and temporary storage of contaminated
materials on site to $4,131,000 for the alternative of disposal at a
commercial nuclear waste disposal site. These estimates are
comparable to the data presented in Table VI-2 of the EPA Technical
Summary Document.
Staff Response - We agree that the costs of remedial actions
would generally greatly exceed $500/acre (See Section 2.3, comments 7,
8 and 9). The numerical estimates provided are very useful and give
an additional perspective applicable to decisions on implementation
options.
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15
EDITORIAL COMMENTS - The following comments were accepted but were
considered editorial in nature.
Department of Energy
Page V-6, lines 9-12
The admonition to seek site-specific data seems to be
inconsistent with the qualification of the first sentence of this
paragraph, which says the method is to be employed only when
site-specific data are "difficult or impossible" to obtain.
Page V-7, lines 19-23
"Under such conditions" requires definition. On the previous
page "characterization of the source term" is considered necessary
only "when these levels approach that of the Guidance
recommendation." Here the qualification is lost.
Page V-ll, lines 1-4
This sentence seems to contradict the discussion on p. 17 of
Annex II where the significance of children eating dirt was dismissed
because it required "extreme assumptions."
Page V-12, Section 5.1.1
No reference is provided.
Page V-14, lines 21-24
This sentence would be improved by eliminating the last four
words. As it stands, it seems to say you can prove whatever you want
with statistics. Appropriate references should be provided.
Page V-15, lines 1-9
This paragraph introduces for the first time, without definition,
terms such as "true fraction," "lower bound," and "upper bound." This
leads to confusion, since the paragraph appears to acknowledge that
portions of land area may reasonably exceed the limiting soil
concentration. Extensive rewording is suggested.
Page V-15, lines 15-17
Not all transuranics have long half-lives.
1 Hft
JL £ l.«
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16
Page V-16 . , . '
It is very easy to misinterpret this page as a listing of always
available alternatives among which one chooses on the basis of
site-specific costs. It should be made clear that at many sites many
of these options would not be available. ;
Page V-17, lines 10-13
This sentence is not clear. It should be reworded or>deleted.
-------
3.6 Annex VI - Environmental Assessment
1. Department of Defense
It is not clear whether the reference to NEPA ,is in the context
that EPA has to file an EIS for the proposed Guidance or that the
various agencies who will be involved in clean-up have to file an
EIS. Clearly, for major Federal actions, an EIS is required, thus, it
is assumed any cleanup of any magnitude would require such a
statement. Which is the case being presented? The relationship is
not distinct. Clearly, if an EIS has to be filed before any cleanup
is undertaken, the various requirements will cause delay in acting.
What is done in the meantime—stabilization, evacuation of people,
etc. This section serves to confuse rather than clarify, (p-1)
Staff Response - Implementation of the Guidance is the
responsibility of the agencies having site jurisdiction or causing
environmental contamination. In the event of future incidents, it is
assumed that proper and expeditious remedial actions appropriate to
the occasion will be taken. For existing situations, where time is
not a critical factor, the evaluation of all impacts and alternatives
should be considered and the preparation of an EIS might well be an
integral part of the decision making process.
2. Department of Energy
This paragraph would seem to require an Environmental Impact
Statement or Assessment before any cleanup action is taken. Thus, in
compliance with Annex V, the area must be surveyed to a precision of
5-10%, uptake in potential food crops measured, air samples taken at
weekly intervals, etc. A dose assessment must then be made and
alternatives considered, taking account of monetary, societal, and
environmental costs. All of this could take from one to several
years. Thus, if any land is contaminated by transuranics (presumably)
to any level and for any size area), the area must be stabilized and
restricted until all this is done. If the above description is not
the impression intended, the paragraph should be rewritten to clarify
the intent, (p-1 .lines 20-26)
Staff Response - The Guidance does not state the requirements for
an Environmental Impact Statement. Such a requirement may be dictated
by the magnitude of contemplated remedial actions, and appropriate
discisions in this regard must be made by responsible State and
Federal officials. It is intended that such decisions be governed by
common sense and a concern for the health and safety of the
population, rather than by a strictly legal interpretation of the
guidance document.
-------
3. Department of Energy
At some point mention should be made of the possible
complications posed by an endangered species living in a contaminated
area, (p-2)
Staff Response - Such detailed evaluations must be considered on
a site-specific basis.
4. Department of Energy
"Temporary disruption of normal activities" is a very optimistic
way of describing the more realistic description of. the previous
comment, (p-2, line 7)
Staff Response - The magnitude of adverse impacts is a function
of the scale of remedial actions. "Temporary disruption of normal
activities" is intended to apply to that range of anticipated remedial
actions which could be expected to occur for events with a higher
probability of occurrence.
5. Department of Energy
"Animals...and fauna" is redundant. (p-2, line 9)
Staff Response - We agree.
6. Department of Energy
The fact that the detailed study of ecological impacts will not
be received until the end of 1977 implies that this Guidance was
formulated without knowledge of such detailed impacts.
(p-2, lines 17-20)
Staff Response - True. The Guidance was derived on the basis of
health impacts, not a detailed knowledge of ecological impact for
remedial actions. Such knowledge would foe most useful for evaluating
alternatives of remedial actions, which is beyond the scope of the
Guidance.
7. Jefferson County Health Department
If the guidance from the International Commission on Radiation
Protection is to be considered I think it is important to know who is
on the commission, which industries or agencies they represent, and
whether the members have signed statements of disclosure concerning
financial and other interests which may impinge on their duties as
commission members. (p-5)
173
-------
Staff Response - The recommendations of the International
Commission on Radiation Protection have been rejected as inappropriate
for this Guidance. Therefore, the remainder of the comment is
irrelevant.
8. Department of Energy
Whether these values are "unacceptable" would depend upon the
probability of exposure from other sources. If all sources of
exposure are very unlikely, any one of them should be allocated a
major fraction, if not all, of the limit. This seems to be a basic
area of disagreement between the philosophy of this Guidance, and what
other respected bodies consider to be a more reasonable philosophy.
(p-5, lines 9-13)
Staff Response - The rationale and limitations for the statement
are given in the remainder of the paragraph. The Agency does not
agree that higher dose rate limits, with or without the principle of
dose allocation, represent a "more reasonable philosophy."
9. Department of Energy
Does the Guidance permit this? "Could well be acceptable" is not
sufficiently precise, (p-5, lines 13-15)
Staff Response - The Guidance is intended to permit, and even
encourage, some judgment on the part of the implementing agency.
10. Department of Energy
It would be helpful if the Colorado standard was interpreted in
terms of units more directly related to the EPA Guidance.
(p-5, lines 21-23)
Staff Response - The Colorado Guidance is stated on a legally
defined basis and cannot be converted to other units without
introduction of certain assumptions. The EPA guidance is not stated
in terms of a soil concentration level, and correlations must be made
on a site-specific basis.
11. Jefferson County Health Department
Reference is again made to the present standard of 2 dmp/g of dry
soil adopted by the State of Colorado in 1973, representing about 25
times average plutonium fallout background for Colorado.
Unfortunately, the standard does not define the meaning of the word
"soil" which has been taken to mean agricultural soil. I agree that
the Colordo standard cannot be considered in the context to long-term
public health protection, since it is neither well defined nor
conservative, (p-5, line 22)
174
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Staff Response - The Guidance recommendations refer to dose rate
limits, and reference to a "soil standard" is inappropriate and
erroneous.
12. Department of Energy
The intended meaning of these two sentences is not clear.
(p-6, lines 4-10)
Staff Response - The intended meaning is to acknowledge that the
Colorado standard may serve as a reasonable means of protection for
construction workers and that the objective of public health
protection is not given as its primary purpose.
13. Department of Energy
See Department of Energy comment of page VI-1.
(p-7, lines 23r25)
Staff Response - The sentence states that "if is important that a
detailed environmental impact evaluation be made...prior to
implementation." The comment probably confuses this admonition with
the requirement for an Environmental Impact Statement. The above
statement again illustrates the need for judgment on the part of the
implementing agency.
14. Department of Energy
This section considers the projected impact of guidance at
existing sites. Should there not be a section that considers the
impact at hypothetical future sites of contamination, since this
Guidance is designed also to apply to future contamination events?
Several typical accidents should be analyzed, ranging from the maximum
to a more normal release, occurring in several types of areas. This
would indicate whether costs are in the range of thousands or billions
of dollars, and given some indication of societal and environmental
costs, (p-8, Section IV)
Staff Response - The agency staff believes that the consequences
of potential accidents should be considered in the Environmental
Assessment of similar evaluations for specific facilities and/or
activities (e.g., transportation of fuel elements), but not part of a
generic guidance. . , ,,,.<...
15. Jefferson County Health Department
The report states that "the present maximum permissible lung dose
rate of one millirad per year is equivalent to about 100 times the
current contamination levels derived from fallout." This can be
contrasted with the Colorado standard, i.e..about 25 times fallout.
175
-------
I emphatically disagree that soil concentration data of plutonium at
Rocky Flats indicates that offsite areas are "probably in compliance
with the guidance." This is not supported by survey data. I would
agree that "more intensive evaluation may be needed to determine the
actual dose rates to the general population." Again in Table 6-1, I
would disagree with the estimates of the area contaminated offsite.
My recent report to the Jefferson County Board of Health of a survey
of the contamination over the entire area demonstrates a large area
with contamination greater than 100 times background and a much larger
area with contamination 25 times background level.
(p-8, Section IV)
Staff Response - The conclusion that offsite areas at the Rocky
Flats Plants are "probably in compliance with the guidance" must be
characterized as tentative and subject to confirmation. It is based
primarily on extensive environmental monitoring data by both the U.S.
Department of Energy and the Colorado Department of Health, and
includes evaluations of air concentrations and soil contamination
levels as input for suitable calculational models to derive dose rates
to exposed individuals.
16. Department of Defense
Annexes V and VI devote little effort to remedial action costs
and uses $500/acre as an estimated cost. This cost is grossly
unreasonable and underestimates actual expense involved in many cases
for existing sites. A specific example is Enewetak where clean-up
cost is at least an order of magnitude greater. Of equal importance
are costs that could be incurred for sites that may be contaminated in
the future, for a different set of circumstances could be involved.
For instance, populated areas might be involved, requiring evacuation,
personal property decontamination, stoppage of industry, restriction
of agriculture and others. Certainly, this would involve costs
associated with the project and could exceed the $500/acre associated
by the EPA with the proposed Guidance. Would this, if considered,
have made any influence upon the level chosen for dose limitation?
Actual operating experience, at least in one instance, does not
support the EPA conclusion "...that the cost of implementing the
guidance at the reference level would be reasonable and achievable".
(p-10, Table VI-1)
Staff Response - The agency staff considers Enewetak to be a
special case that need not necessarily fall under this guide. One
reason is that the restriction of access to the contamination site is
an option to be considered under this guide, but this option cannot be
considered for Enewetak. The $500 per acre is a minimum, and was not
intended to imply that all remedial measures can be performed at this
cost. The recommended guide establishes what is believed to be an
acceptable level of risk at a cost that is not believe to be
176
-------
unreasonably high. Costs of treatment for existing and possible
future sites are discussed in the Supplement to the Proposed Guidance
and Dose Limits for Persons Exposed to Transuranium Elements in the
General Environment.
17. Department of Energy
Table conveys a false impression because of the unrealistic cost
estimate. It also appears unreasonable that changing the "reference
level" by a factor of 3 could have such a major effect on the area
requiring remedial action. (p-10j Table VI-1)
Staff Response - Estimates of cost of remedial actions are
speculative at best and cannot be derived on a generic basis. For the
relatively low environmental contamination levels presently existing
outside the boundaries of these facilites, the costs of remedial
actions could be expected to be of the order of magnitude stated.
The estimates of areas defined within contamination contour lines
were derived from published environmental monitoring data.
18. Depatment of Energy
Why is the population of the area relevant? The screening level
seems to be independent of the number of people affected. Or is it to
be understood from this sentence that such considerations are relevant?
(p-11, lines 5-6)
Staff Response - The population at risk is a factor in evaluating
the total impact of a given hazard.
19. Department of Defense
Again, the $500/acre cost is not generically realistic and dose
not consider many factors such as decontamination of buildings,
machinery, homes, loss of productivity, planning, etc.
(p-13, Section V)
Staff Response - The $500 per acre figure was a minimum. Costs
of treatment for existing and possible future sites are discussed in
the Supplement to the Proposed Guidance on Dose Limits for Persons
Exposed to Transuranium Elements in the General Environment.
20. Department of Energy
This section presents an inadequate consideration of costs of
remedial action. It says "the Agency has evaluated the'available_
methods and costs" but does not tell how this was done, nor does it
give any reference to this study. The results are presumably
summarized in Table VI-2, which is difficult to read. It is clear,
177
-------
however, that in these estimates no consideration has been given' to
costs of population evacuation, or monitoring; decontamination of
homes, roads, or commercial areas; income losses from cessation of
agricultural or commercial activities; cost of Environmental Impact
Assessment; to mention but a few. Nor does it give any consideration
to environmental costs, (p-13, Section V)
Staff Response - The complete sentence reads "The Agency has
evaluated the available methods and costs for cleanup and restoration
of contaminated land areag." Most of the items cited may represent
additional or extraordinary costs, and do not necessarily represent a
cost of implementation of the Guidance.
21. Nuclear Regulatory Commission
Some NRC licensed facilities are located in areas having other
buildings and structures which would be substantially more costly to
decontaminate than for a facility located in a remote area. A recent
"Draft Engineering Evaluation of the Latty Avenue Site, Hazelwood,
Misssouri", by Ford, Bacon, and Davis, Utah, Inc., dated January 1978,
indicates that the five remedial action alternatives evaluated for
18,300 cubic yards of contaminated material at the 10 acre site, range
from $457,000 for clean up and temporary storage of contaminated
materials on site to $4,131,000 for the alternative of disposal at a
commercial nuclear waste disposal site. These estimates are
comparable to the data presented in Table VI-2 of the EPA Technical
Summary Document, (p-14, Table VI-2)
Staff Response - We agree that this range of costs is reasonable.
22. Department of Energy , .
Table requires a number (presumably VI-2), a title, enlargement
to readable size, and particularly, appropriate references.
(p-14, Table VI-2)
Staff Response - The basis, data, and content of Table VI-2 are
given in Selected Topics: Transuranium Elements in the General
Environment", EPA Technical Note ORP/CSD-78-1 (1978).
178
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.4. ESTIMATED COSTS OF REMEDIAL ACTIONS
4 • 1 Introduction
The primary costs of implementing the Guidance are the costs of >
bringing all sites exceeding the .recommended soil limit into
compliance. These include presently existing contamination sites as.
well as sites that may become contaminated in the future. The costs
of decontaminating presently existing contamination sites are believed
to be small, so that the major costs of implementation are expected to
be incurred in the event of future accidents or incidents that release
transuranium elements to the environment. Since therpotential sites
of future accidents cannot be identified, a procedure is used for
estimating an upper limit to the expected annual costs of remedial . j
measures.
There are a number of difficulties in determining the appropriate
measures for .attaining compliance for contaminated lands. The major
difficulty is that there has been little experience w.ith the.
decontamination of soils contaminated with transuranium elements.• :
Thus there is little expertise for determining the appropriate action
to be taken to reduce the contamination level on a given piece of land
to an acceptably low level. In addition, the determination of the
appropriate procedure requires information on site-specific factors
that are best, determined from on-site analysis by persons familiar
with the task to be carried out and the, resources available. It is
especially difficult to determine the appropriate remedial measures
for new accidents, where it is important that prompt action be taken
to restrict dispersion of transuranium elements into the environment.
4.2 Cost Estimation
Since the Guidance requires that the maximum individual dose be
at or below a specified limit, and does not specify specific remedial
actions, cost-minimization is the appropriate criterion, to identify
the preferred set of remedial actions from the set of actions that.,
will bring the site into compliance. The total cost of each possible
set of options that can attain compliance should be evaluated to
determine the least-cost method. Environmental costs and other
non-monetary costs, not quantifiable in monetary terms should, if
possible, be considered in the evaluation. Whenever feasible, it is
desirable that costs be quantified monetarily, but if this is not
feasible, they should be quantified in non-monetary terms. Narrative
descriptions should be used when no quantification is possible. A
difficulty is that different combinations of decontamination
procedures are expected to have somewhat different mixes of monetarily
quantifiable, non-monetarily quantifiable, and non-quantifiable
costs. Judgment must be used in weighting the different elements of
these costs.
17S
-------
Most non-monetarily quantifiable and non-quantifiable costs are
site specific. Because of the great difficulty in estimating these,
especially in the event of future accidents, only the monetary costs
of implementation will be discussed here. Cost of implementation is
considered to be the monetary cost, on a nationwide basis, of
performing the remedial measures sufficient to reduce the exposure to
the critical segment of the population at each site to the recommended
level.
Two sources provide the unit cost estimates used in this
evaluation, an EPA study entitled "Available Technology and Unit Costs
of Cleaning Plutonium Contaminated Land Areas," and a document
entitled "Department of Energy Comments on Decontamination Costs
Discussed in the EPA Proposed Guidance On Dose Limits for Persons
Exposed to Transuranium Elements in the General Environment"
(Enclosure II to the Department of Energy's comments on the proposed
EPA guide for transuranium elements in soil). Table 4.1 is reproduced
from the EPA study. It summarizes the results of the study.
The Department of Energy has extensively analyzed the costs of
remedial measures for lands contaminated with transuranium elements.
Their estimates are used to supplement the EPA estimates because they
consider a number of land use categories and decontamination
procedures not considered in the EPA study.
Table 4.1 summarizes the estimated costs expressed in 1974 prices
for a variety of cleanup measures. The costs shown in Table 4.2 are
derived from Table 4.1, but are adjusted to 1977 prices.
i
Although costs of Table 4.1 have been assembled to facilitate the
estimation of the unit costs of cleanup for different remedial action
strategies, the costs of individual cleanup procedures are also
available from the table. Table 4.3 presents the individual cleanup
procedures costs (adjusted to 1977 dollars), derived from EPA
estimates (Table 4.1) and from DOE estimates. Most of DOE's estimates
were taken from Table 14 of their Enclosure II.I/ DOE costs have
been adjusted to express dollars per acre.
I/ There are two errors in the costs shown in DOE's Table 14. Both
are cost estimates credited to EPA. The first is that EPA estimates
topsoil replacement to cost $4500 per acre, which is equivalent to
$1,112,000 per square kilometer rather than $562,200 per square
kilometer shown in Table 14. The second is in the cost of fencing.
EPA estimates that fencing costs an estimated $30,000 per mile (1974
dollars) rather than the $3,700 per mile (i.e. $2,300 per kilometer)
expressed in Table 14. Corrected cost estimates (adjusted to 1977
dollars) are shown in Table 4.3.
180
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TABLE 4.1
Decontamination Costs
EMICAL: VICETATIVE
VACUUM INC WITH TRENCH DI
B. STA1ILJZATION
;J RANGE OttJMO]
LAKUUEUOOI
M. |RANC£:ItTCO.M!Oe/AI
[ASSUME:»1tafAI
U STABIL.HH AND r L2»M
M • tIMOWA
NCTERM OR '- VECITATl
MANGE: I1
SSKBSS-
IAKUKE: -
RAHaE-Ms.*M8
[ASSUME: -BKVA1
«- COSTS INClUDt
OtS. ANO UNLOAOmC AT HJ
ULTIMATE WEKMAL
%a°
flAI«nE_ ASSUUE
W LirAlWN 1
'i-i1 S
(MlO l«00) -1IOM/H
wuzcn SIM 1140 ^nxM
SEEDING IltO }IE> -11WA
SOIL A
^EATl
OPTIDHS OH AL-TERHAIIVES:
AtlONI BAMCE
PPLICATION iraO'KO
<
j
3E
TOTAL NMMCT COSTS;
ASSUU6D AVERAGES
, -HANSES
TION REMOVAL
-------
4
TABLE 4.2
Decontamination Costs Derived From Table 4.1
Remedial Action
Disposal
Estimated Cost,
(1977 Dollars)
Stabilization & Restoration Only
Shallow Plowing
Deep Plowing
4" Top Soil Cover
8" Loom & 4" Top Soil Cover
Scraping
Scraping
Scraping
Vacuuming
Scraping or Vacuuming
Scraping or Vacuuming
In Place
Dilution In Place
Dilution In Place
In Place
In Place
Windrows on Site
Mounds on Site
Trenches on Site
Trenches on Site
Off Site in State
Repository
Off Site in Federal
Repository
2,400/A
3,000/A
2,850/A
5,550/A
11,050/A
,150/A
,900/A
5,550/A
6,450/A
4,
5,:
145,000 - 190,000/A
600,000/A
182
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TABLE 4'. 3
EPA and ,DOE Unit Costs of Decontamination
Description
Short term stabilizer
Long term stabilizer
Vegetation removal
Corn
Other Crops
Grass sod /<,
Slightly wooded
Heavily, wooded:
Soil removal
Scraping
Front end loader
Manual labor
Vacuuming
Scraping into ,
windrows
Scraping into,
mounds
Scraping into
trenches
Vacuuming with
trench disposal
Soil replacement
4" topsoil
4" loam
4" topsoil & 8"
loam
12" loam
Shallow plowing (12")
Deep plowing (36")
Deep plowing of pasture
land
Restoration
Fertilizer
Lime
Mulch
Seeding
Seedlings
Shrubs
EPA
Estimated
Cost
810/A
690 /A
NE ,«»)
NE
580/A
1,440 /A
2, 300 /A
950/A . ,
. NE .-•
..•NE
1,2(1Q/A
230/A
690 /A
1,960 /A
2, 890 /A
5, 180 /A
2,670/A
10, 700 /A
8, 280 /A
50 /A
230/A
NE
170/A A
25 /A
140 /A
230/A
70 /A
1,500 /A
DOE1"8'
Estimated
Cost
$ 300 /A
420 /A
80 /A
16/A
920/A
NE
NE
920/A
- , 1,700 /A
2,900/A
NE
NE
NE
NE
NE
6, 500 /A
NE
NE
NE
14/A
140/A
610/A
270 /A
NE
NE
NE
NE
NE
DOE Definitions
and
: Assumptions
Two weeks water fixation
Long acting stabiliser
Field sod removal ,
Grader
25cm 'depth
1 meter depth
Includes reseeding
Includes seed (materials
only)
See "Fertilizer"
-------
TABLE 4.3 (continued)
Biobarrier
Lawn sod removal
Vacuumized sweeper for
streets
Fire hosing
Decontamination of
homes
Lawn resodding
Decontaminating
commercial areas
Fence (based on
perimeter length)
Surveillance (based
on perimeter length)
Offsite disposal
(including packaging)
and 1000 miles tran-
portation)
Federal Repository
State Repository
NE
NE
NE
NE
NE
NE
NE
34,500/mi
NE
586,500/A
138,000/A
72,000/A
1,140/A
160/A
200/A
350/House
5,200/A
3,700/A
75,600/mi
9,700/mi
482,500/A
59,500/A Commercial
repository
(a) Taken from DOE Enclosure II, Department of Energy Comments on Decontamina-
tion Costs Discussed in the EPA Proposed Guidance on Dose Limits for
Persons Exposed to Transuranium Elements in the Environment, Table 14.
(b) NE - No estimate.
(c) Cost taken from document sited above.
Table 10, p. II - 18
Reference found in footnote (a) to
104
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The two agencies' costs can be compared for those cases where
both made estimates. The Table 4.3 shows that most estimates are
within a factor of three. Although this is a rather big difference,
it is no larger than might be expected considering the lack.of
experience with this form of decontamination. There is no apparent
uniformity with respect to which agency's estimates are the higher.
It can, therefore, be considered that EPA and. DOE do not greatly
differ in their estimates of the costs of the individual procedures
that must be undertaken to restore transuranium contaminated lands.
There are two general techniques for restoring lands to
unrestricted use: (1) all land surface soils are removed and
transported to another location for final disposal; and (2) plowing,
which leaves the contamination in place, but lowers the concentration
levels in the top most land surface. . When the surface soils have been
removed, they may be stored on-site, or off-site in state or Federal
repositories. On-site storage is an option that can be used, where a
part of the site can be reserved for the disposal of the^surface soils
removed from other portions of the site. In most cases it is
estimated that no more than 5% to 10% of the site is needed for the
disposal of the contaminated surface soils removed from the remaining
90 to 95% of the site. The part of the site used for disposal must be
purchased and permanently subjected to.controlled access, but there
would be unrestricted access to the remainder of the site. An
alternative that could be used for lands adjacent to a Federal
facility would be that a portion of the facility grounds be reserved
for the purpose' of on-site disposal. On-site storage avoids the
extremely high costs of off-site storage in state or Federal
repositories. Tables 4.1, 4.2 and 4.3 pr.ovide estimates of the costs
of on-site disposal. DOE did not consider this type of treatment.
Land use restrictions for entire contamination sites should be
considered if such restrictions are the least, cost option, although
the circumstances of each particular site must be evaluated. Costs
include acquisition of the site, the costs of fencing, guards, and any
other measures required to maintain restricted access. Costs also
include all remedial measures that may be required on the restricted
area to prevent dispersion of the contamination to areas outside the
restricted area, such as stabilization, plowing, the .development of
on-site storage in trenches., windrows or mounds, and the establishment
of ground cover. Costs would also include the dismantlement,of houses
or other facilities that may be on the^site. .
Land use restrictions are a form of remedial action cost not
quantifiable in dollars.' Such restrictions are likely to impede the
natural flow of traffic in the community in which they are used; and to
block its orderly development. Also, the restricted areas are likely
to become despositories of trash and other waste as well as become
overgrown with weeds unless there are ongoing maintenance programs.
The disruptive nature of land use restrictions is so important,
especially in urban or industrialized areas, that they are probably
feasible only in localities of low population densities where there
are few or no known alternative uses for the land.
185
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8
DOE analyzed^the cumulative costs of remedial action at three
real (but unidentified) sites. Two area sizes were used at each site
for a total of six sets of costs. The two sizes considered were
1km and 10km2. These sites are devoted to a number of uses,
including crops, orchards, pasture, woodlots, forests, shoreline, and
residential and commercial areas. The areas analyzed are quite large;
large enough that DOE's cumulative decontamination costs are not
realistic estimates of the cost of future accidents. Therefore, the
total costs expressed in the third column of Table 4.4 are not useful
for estimating the costs of future accidents. However, when these
costs are expressed as functions of unit areas (i.e., $/km2 or $/A),
they serve as possible estimates of the average unit costs of future
accidents.
The last column of Table 4.4 summarizes the average unit costs
for the six sites analyzed by DOE. Most of the content of this table
was taken from Table 13, Enclosure II. Alternative methods of
treatment are given in the second column. Site restriction refers to
the purchase of all lands and the maintenance of fences to restrict
access to the entire contamination area and to the measures needed to
prevent dispersal of transuranics. The other three treatments refer
to the remedial action taken on open lands, where earth removal for
off-site storage, shallow plowing, and deep plowing are alternatives.
The remedial measures on all portions of these sites that cannot be
plowed are the same for all three treatments. Reference site 2 had no
open lands that could be plowed.
The mean and standard deviation for the four sets of remedial
actions on the six sites are shown at the bottom of the table.
Comparison^of these values shows that for similar treatment strategies
there^is little difference in the average costs of treatment for the
six sites, but that there are comparatively large reductions in costs
when open lands are plowed. This demonstrates that measures that
avoid the high cost of soil removal for final disposal in a state or
Federal repository can significantly reduce the cost of remedial
action. Calculations based on DOE's Table 11 and 12 (Enclosure II)
show that off-site disposal at Federal repositories accounts for 82 to
98% of the costs of treating the six sites when earth removal is the
treatment strategy.
186
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.9
. .,. . TABLE 4 .A
Comparison of Estimated Cumulative Costs per
Unit Area for All Sites and Treatments*
Area
1.0 km2:
Reference. Site One
Reference Site Two
Reference Site Three
10.0 km2:
Reference Site,One
Reference Site Two
Reference Site,Three
Treatment
(a)
Total Cost
Cost/acre
($ Million.1977) ($ Thousand 1977)
ER
SR
;, DP
SP
. ER
. SR
ER
. SR
DP ,
SP
ER
SR
, . DP
SP
ER . .
SR
ER .
SR ;
DP '
SP
115.6
95.2
, 12,9
11.4
93.3
133.5
.121.2
95.4
, 21.2
19.5
11.2.7 .0
1062.4
159.5
145.2
, 1103.1
1080.7
1213.0
'.,'..-' 942.7
144 . 8
128.5
468
385
52
46
378,
540
490
386
86
79
456
430
; 65
59
446
437
491
382
59,
52
Average cost,, earth removal (6 sites) = $454,000/A; standard deviation
= $42,000
Average cost, site restriction (6 sites) - $427,000/A; standard deviation
= $61,000 . • • .
Average Cost, shallow plowing (4 sites) = $59,000/A; standard deviation
= $15,999
Average cost, deep plowing (4 sites) = $66,000/A; standard deviation
= $15,000
"^ ER = Earth removal to depth of 5 cm; DP = Deep (1-m) plowing; SP = Shallow
(25-cm) plowing; SR = Site restriction, including construction of a
biobarrier.
*Source: Enclosure II, Department of Energy Comments on Decontamination Costs
Discussed in the EPA Proposed Guidance on Dose Limits for Persons Exposed to
Transuranium Elements in the General Environment, Table 13.
1 P^7.
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10
4.3 Recommended Action Levels
It would be useful to establish the contamination concentration
levels at which different remedial actions are appropriate. Since a
variety of circumstances bear on the determination, no universally
applicable rules can be established. There is, however, some
information for establishing the appropriate levels where some forms
of remedial action may be considered.
The threshold of remedial action is established by the
recommended soil screening level of 0.2 uCi/m2. No remedial action
need be undertaken, for sites with soil concentrations below this
level.
The Department of Energy has established that shallow plowing
(i.e. 10 inches) reduces the surface contamination by a factor of 5,
to 20% of its former level, and that deep plowing (3 feet) reduces it
by a factor of 20 to 5% of its former level .I/
Based on these estimates, and on the recommended soil screening
level, it can be established that a contamination level equal
1.0 uCi/mz (before remdial action) is the upper limit for lands for
which shallow plowing is sufficient to bring the site into compliance,
and 4.0 uCi/m^ is the upper limit for which deep plowing will attain
compliance. Plowing is, of course, a viable option only for open
lands where soil characteristics permit. Since deep plowing will
bring sub-surface soils to the surface, some form of restoration, such
as a soil cover of topsoil or loam may be required.
EPA estimates that land with a surface contamination below 10
2 (before remedial treatment) may be safely stored on-site in
windrows, mounds or trenches. Such on-site storage requires that
access to the storage area be controlled and that measures be taken to
stabilize the surface soils from wind and water erosion. Controlled
access is required to assure the soil surface is not disturbed and
that the integrity of erosion prevention measures is maintained.
Other remedial measures are required for sites contaminated above
10 uCi/m/. The most likely is the removal of the surface soils for
transport to state or Federal repositories.
It is possible that some of the very high costs of storage at
state and Federal repositories can be significantly reduced by methods
that concentrate the contamination, reducing transportation and
storage costs. Concentration has been demonstrated for plutonuim,
J7Appendix C, pg. 6-4
188
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where the major fraction of the plutonuim is,generally attached to the
smallest sized-soil particles..,This leaves the larger particle sizes,
which usually constitutes the major fraction of the soil, relatively
free of contamination. This subject is more fully discussed in Annex
II to the "Proposed Guidance on Dose Limits for Persons Exposured to
Transuranium Elements in the General Environment."
As discussed in the "Proposed Guidance", the soil screening level
is conservatively chosen to provide that the recommended dose level .be
met for the most adverse soil characterstics. The recommended action
levels have the same conservatism. Since these action levels are
conservative, the circumstances of a particular site may be such that
plowing or on-site storage may achieve the recommended dose limit for
sites contaminated above the action levels derived here.
^•4 The Cost of Implementing The Guidance ,
There are two components to the costs of implementation. The
first is the cost of bringing presently existing sites into compliance
and the second is the cost of remedial measures undertaken for
accidents that may occur after promulgation of this Guidance.
4.4.1. The Cost of Implementation on Presently Contaminated Sites
There are four Federal sites in the United States that presently
have transuranium element contamination above ambient levels beyond
their boundaries. These include the Rocky Flats Plant in Jefferson
County, Colorado, Mound Laboratory in Miamisburg, Ohio, Nevada Test
Site in southern Nevada, and Trinity Test Site near Alamogordo, New
Mexico. The majority of all contamination released is confined within
areas under the direct control of the Federal government, which
imposes restrictions on the access and use of these areas,. Relatively
small amounts of transuranium element contamination exists outside the
boundaries of these sites on lands generally accessible to the
public. The following discussion is intended to supply a perspective
for applying the Guidance recommendations to these sites in terms of a
soil concentration reference level derived on the basis of generic
data, which, with a very high degree of probability, would be expected
to result in an inhalation dose to an individual not to exceed the
Guidance recommendations. Use of such a soil contamination level is
intended solely to provide a basis for comparisions and does not imply
direct correlation with the dose rate recommendations. A brief
description is given for each site and the general contamination
pattern is indicated. Numerical comparisions to show the estimated
areas of limiting contamination to one-third and one-tenth the
reference level, and of allowing a value ten times greater than the
reference level are given in Table 4.5. Comparisons are made in terms
of areas outside the boundaries of these sites.
189
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12
The Rocky Flats Plant produces components for nuclear weapons.
Barrels containing cutting oil slowly corroded and some of the
contents eventually leaked into the environment and were dispersed.
On the basis of soil concentration data, all off-site areas at the
Rocky Flats Plant would probably be in compliance with Guidance
recommendations. However, more intensive evaluation may be needed to
determine the actual dose rates to the general population, ,
particualarly in the most highly contaminated areas east of the
plant. The area is sparsely inhabited and there are few people living
in the particular area of concern. The off-site area contaminated.to
a level one-tenth the screening level comprises about 1.6 mi2 with a
current population of less than 600. No uncontrolled areas are
contaminated to a level greater than ten times the screening level.
All local water supplies are expected to yield ingestion dose rates
well below the Guidance recommendations.
Mound Laboratory is a major research and development site for
fabrication of radioisotopic heat sources used for space and
terrestrial applications. In 1969 a pipeline transporting a Pu-238
waste solution ruptured, spilling the contaminated solution. The
plutonium migrated slowly into nearby waterways. The majority of the
plutonium is now sorbed and fixed on the sediments of the North and
South Canals. Maximum concentrations are to 1 to 3 ft. below the
sediments surface and currently do not pose any radiation problem,
since very little of the plutonium is in soluble form and the canal
water is not used for drinking purposes. Banks immediately adjacent
to the canal and overflow creek subject to occasional, flooding have
maximum plutonium concentrations exceeding the reference level. The
amount of land in question is about 0.01 mi2 and there are no people
living on this land. There are no areas with transuranium element
contamination 10 times the screening level. The amount of land
contaminated to one-tenth the screening level is the same as the
amount of land above screening level, because the nature of the
contamination event limited the contamination to the waterways and
adjacent banks. No immediate cleanup is indicated for this site, but
continued surveillance will be required.
The Nevada Test Site covers an area of 1400 mi2 with additional
exclusion zone extending 16 to 48 miles. Major programs at NTS have
included.nuclear weapons tests, testing for peaceful uses of nuclear
explosives, and nuclear reactor engine development. These activities
have resulted in plutonium contamination in certain areas of the test
site and exclusion areas and slight contamination (above background
levels) outside the exclusion areas. There are no known uncontrolled
areas which have transuranium element contamination exceeding the
reference level. Land contaminated to one-tenth the reference level
or less covers approximately 165 mi2 with a resident popluation of
less than 240 people.
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The Trinity Test Site was the location of the first nuclear
explosion. No other nuclear explosion tests were performed at
Trinity. A site survey was performed by EPA during 1973-74 to
determine residual plutonium concentration contours. The highest
plutonium comtamination levels in uncontrolled areas ranged from 0.2
to 0.9 uCi/m2. The amount of land contaminated to a level one-tenth
the reference level covers less than 300 mi2, with fewer than 500
people living in the area in small towns, ranches, and farms. On the
basis of the limted available data, no major remedial actions would
appeal to be indicated for this site.
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14
TABLE 4.5
Areas of Existing Sites Requiring Remedial Action for Several
Possible Levels of Maximum Soil Concentrations
Reference Level 10 Ref. Level 1/3 Ref. Level 1/10 Ref.Level
0.2 uCi/i
Rocky
Flats
Plant
Neveda
Test
Site
Trinity
Site
Mound
Lab.
0.07
200 Acres
51.000 Acres
13.000 Acres
6 Acres
0.02
1,000 Acres
106,000 Acres
192,000 Acres
6 Acres
192
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15,
In summary, it appears that few if any remedial measures are
presently needed on the four sites identified in Table 4.5, although
some action may be required when the canals.at Mound Laboratory are
drained. Therefore, the costs of meeting the Guidance for presently
contaminated sites are expected to quite low. " . -
An assumed minimum cost of $500 per acre for remedial action was
the basis of the discussipns in the "Proposed Guidance on Dose Limits
for Person Exposed to Tansuranium Elements .in the General
Environment". This cost was introduced to demonstrate that, even if
costs of remedial action were as low as $500 per acre, the costs of
proposing a dose limit equivalent to a screening level substanially
lower than 0.-2 uCi/m^ would be prohibitive.. However, it is
recognized that realistic estimates of costs of implementing the
Guidance ordinarily must be based on unit cost estimates that are much
higher than $500 per acre.
4.4.2. Considerations for Estimating the Costs in the Event of
Future Releases of Transuranium Elements to. the Environment
Strictly conceived, the costs of remedial measures required to
implement this Guidance for potential future accidents are the costs
over and above those that would have been undertaken in the absence of
this Guidance. Unfortunately, this difference, cannot be estimated.
Therefore, to the extent that costs of required remedial measures can
be estimated, they will be assumed to represent the costs of
implementation.
The remedial measures available for the treatment of soil in case
of future accidents are expected to be shallow or deep plowing, and
soil removal with storage on-site, or in state or Federal
repositories. In urban or industrial areas, houses, buildings,
streets, and sidewalks may require decontamination. Temporary
evacuation of the population may be also necessary. An alternative to
restoring the land to unrestricted use is its acquisition, and the
imposition of restricted access with possibly some form of remedial
action undertaken on the site.
Although little can be done to anticipate the form of future
accidents involving transuranium elements, they should impact on areas
more limited in size than the largest of the presently known sites,
which were caused by above ground tests of nuclear weapons. Since
similar tests are unlikely in the foreseeable future, future
contamination should be confined to areas smaller than the
contaminated areas at the Trinity and Nevada Test Sites. It is to be
expected that increased alertness to the problems of transuranium
element contamination will substantially reduce the reoccurrence.of
events such as Rocky Flats, where the delay in treatment aggravated
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16
the situation. There is also reason to believe that increased
awareness to the health hazards from transuranium elements has
resulted in expanded effort to prevent the occurrence of such
accidents. These measures should help to assure that the areas
impacted in future accidents will be small. • •
'' . ' . ','''.
The costs' of remedial action in the case of future accidents are
correctly conceptualized as the "expected costs" of the measures
undertaken for all future events,that release transuranium elements to
the environment. As used here, the term "expected costs" is analogous
to the statistical concept "expected value". Since there is at least
a small probability that any of a large number of possible events
releasing transuranium elements to the environment could occur in the
future, and since there is a virtually limitless variety of factors ,
contributing to the possibility of such events, expected costs are the
appropriate measure of the costs required by the Guidance.
It can be argued that expected costs are the proper way to
consider the problem from a societal point of view. Society is
subjected to innumerable forms of financial risk from a variety of
events. The events can be assumed to occur randomly; therefore the
evaluation of the costs incurred because of such events should take
into account the estimated probability of their occurrence as well as
their costs when they do occur. Since the accidents that may release
transuranium elements to the environment also .occur randomly, the
costs of required remedial action are one of these financial risks.
Probabilistic expressions of the chance of future accidents
involving the release of transuranium elements, and .of their size and
the types of land to'be impacted are needed to evaluate expected costs.
, Another factor that may enter into the evaluation of the costs of
implementing this Guidance is whether present worth methods should be
employed in 'estimating the costs of possible accidents that may occur
sometime in the future. If so, the estimated distribution of tli.e
probability of occurrence through time would be needed. Since no
attempt'has" been made to estimate this distribution, present worth
methods are not used here. , ;
4.4.3. The Cost of Implementation in the Event of 'Future Releases of
Transuranium Elements to the Environment
Although it must be concluded that there is insufficient
information at this time to estimate the costs of future accidents, it
may be useful to assume some values that place an upper limit on the
expected cost of implementing the Guidance. The basic premise
underlying this estimate is that the expected annual contribution to
new contamination from accidents or other unforeseen events releasing
transuranium elements to the environment will not exceed four acres.
This establishes an upper limit to the expected costs of implementing
this Guidance for cases of future contamination.
194
17
It is realistic to expect that accidents of all sizes can occur.
Therefore, it is assumed that the size of the area contaminated in a
single accident varies, as does the number of accidents occuring in a
year's time. The Figure 4.1 represents a possible distribution for
the expected total number of acres contaminated in a year's time. The
land area requiring remedial action is shown on the horizontal axis
and probabilities are shown on the vertical axis. The number of acres
that can be contaminated in a year's time ranges from zero upwards.
The right hand tail of the function is .infinitely long, expressing
some probability (although small) that the number of acres
contaminated in any single year may be quite large. For example, for
the distribution shown here, there is an 8% probability that the land
area contaminated in any one year will exceed 10 acres. This
distribution has an average value of four acres.
FIGURE
o
c
0)
3
O1
0)
10
3
C
C
10
12 14 16 18 20
Land Area Contandnated per Year (acres)
195
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18
Although the distribution represented in the figure is
speculative, it does incorporate the intuitively desirable feature
that there is a rather high probability that the total area
contaminated by the accidents in a year's time is small, and that the
probability declines as the area contaminated increases.
An upper bound estimate of the costs of the remedial action
required because of these accidents is derived by assuming that the
concentration of transuranium elements is sufficiently high that all
surface soils must be removed and disposed of in Federal repositories.
Assuming the costs of doing this are equal to the average for the cost
of remedial action on the sites investigated by DOE, the average cost
of remedial action would be $454,000/acre (Table 4.4), and the
expected annual cost of remedial action would be four times $454,000
or $1,816,000.
In using per acre costs based on the DOE analysis, it is assumed
that the areas contaminated are diversified in that they contain a
variety of land uses, and may contain residential and commercial
areas, as well»as agricultural and wooded areas. The six large areas
in which these averages are based provide sufficient diversity so that
the per acre costs are considered to be representative of the types of
lands that may be impacted in the .case of a future accident.
If the assumptions underlying the per acre cost estimate are
changed by assuming that the concentration of transuranium in the soil
is low enough that plowing is adequate treatment for all open areas,
the DOE estimates show that the unit costs of treatment would be
reduced to $59,000/acre, and the expected annual cost would be reduced
to $236,000.
These values establish the range $236,000 to $1,816,000 for the
expected annual cost of implementing this Guidance in the event of
future accidents.
In cases where the level of contamination is sufficiently high
that shallow plowing is not adequate to meet the recommended Guidance,
alternatives other than storage in Federal repositories, (i.e. deep
plowing, on-site storage or off-site storage in state repertories) may
be considered. In those cases where these methods prove to be
adequate, the estimated costs of remedial action are expected to fall
somewhere within the range of costs established here.
There is, however, evidence that the low end of this range is
itself high. This is because the low estimate of the upit costs of
implementation (from Table 4.4). was for the case where all .open lands
were plowed, but where the surface soils from areas that could not be
plowed were removed and transported to Federal repositories.
136
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19
Comparison of the costs of storage, in Federal repositories with the
costs of storage in state repositories or>storage on-site (Table 4.3)
reveals that substantantial savings can be realized when the
contamination level is low enough that these types of remedial action
can be used. Therefore, the low end of this range could probably be
lowered, at least to some extent.
The range of costs established here is based on an average annual
contamination, of four acres. Historical evidence indicates that this
value is probably high. The United States has had over 30 years of
experience with activities involving the use of transuranium
elements. These activities have been carried out at a large number of
locations. Nevertheless, problems have been identified at only the
four sites discussed in Section 4.1. As discussed there, it is
believed that little or no remedial action will be required to bring
these sites into compliance with this Guidance. Even though activties
involving the handling of transuranium elements are expected to
increase in the future, past history, and increased awareness of the
danger from the release of these elements to.the environment, gives
reason to believe that the annual expectation of four acres of new
contamination assumed here may be high.
In summary, the annual costs of remedial action in the event of
future releases of transuranium elements to the environment is
expected to range from $236,000 to $1,8167000. Nevertheless, there is
reason to believe that this range may be high, and that future costs
will be lower than estimated.
197
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5. GUIDANCE IMPLEMENTATION
5.1 Int sroduc t ion
Implementation of the Guidance recommendations involves
consideration of all transuranium element environmental contamination
and pathways that could result in radiation doses to persons in the
general population. Such a consideration includes a determination of
the level and extent of existing contamination.and the projections of
actual or potential doses to a critical segment of the exposed
population. This requires an evaluation of the site, a projection of
the radiation dose rates via all applicable pathways to determine
whether Guidance values are exceeded, and initiation of remedial
actions where indicated.
Implementation of the Guidance recommendations is the
responsibility of those agencies having regulatory and administrative
responsibilities for the site in question and/or the materials in use
at a site. A reasonable evaluation of a contaminated site should
include a description of the site and environmental measurements of
contamination levels in environmental media, in sufficient detail to
convey adequate information to the general public. Environmental
pathway and dosimetry models used to estimate radiation doses to
persons should be described to permit evaluation of the procedures
used. If projected dose rates are greater than the recommendations3
protective or remedial actions should be performed such that Guidance
values are not exceeded and will not be exceeded in the foreseeable
future. ' • . ' ...'...'..
In the context of this Guidance, the objective of environmental
sampling and analysis is to derive information for the purpose of
estimating dose rates to pulmonary lung and to bone of exposed
individuals, these dose-estimates are derived on the basis of models
which consider the various pathways by which transuranium elements in
the environment may interact with people and produce exposure to
radiation. Such models describe the characteristics of transuranium
elements in the environment, the manner in which they may be
transported through the air or through food pathways, modes of
interaction with man (including inhalation or ingestion) and, finally,
factors related to the radiation energy deposition in organs and
tissues. In general, dose estimates are best derived from data
acquired from measurements in the dose pathway as close as possible to
the point where transuranium elements interact with people.
Three general procedures can be used to judge compliance with the
Guidance recommendations. These procedures, which are described in
more detail in the following sections, may be used for the entire site
or for portions of the site as appropriate:
199
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a. dose rates can be calculated, using the appropriate dosimetry
models, from measurements of the concentration of the transuranium
elements in air, food, and water at the point of inhalation and/or
ingestion by persons. This is the most direct and preferred method.
b. soil concentration levels of the transuranium elements can be
compared to a "screening level" for soil, defined as that level below
which the concentration of the transuranium elements is not likely to
lead to dose rates in excess of guidance recommendations.
c. dose rates can be calculated from the soil contamination
levels of the transuranium elements using site-specific parameters for
transport models and the appropriate dosimetry models.
5.2 Implementation of Guidance by Estimating Dose Rates to Lung and
Bone
Federal agencies may show compliance for a specific site, or for
sub-areas of a specific site, by certifying that Guidance values for
dose rates to the lung and bone of members of the critical segment of
the exposed popoulation are not being exceeded. The most direct
method is to measure transuranium element concentrations in
environmental media such as air, food, and water at the point of
interaction with people and then to calculate the potential radiation
dose rates using the appropriate dose conversion factors and dose
model parameters. When this procedure is used, adequate documentation
should be provided to demonstrate how dose rates are calculated. The
Agency favors the use of realistic environmental measurements and
realistic mqdel input parameters; conservative parameters should only
be used to the extent necessary to compensate for uncertainties.
In certain cases, compliance with the Guidance recommendations
may be achieved by restricted occupancy of a site, or portions of a
site. Time restrictions for occupancy, or other use limitations, may
be established to limit the exposure of a critical segment of the
population. Such occupancy or use restrictions should be applied only
if remedial actions sufficient to permit unrestricted access are
either impossible or economically prohibitive.
5.2.1 Dose Rate to the Lung
Lung dose rates are calculated using appropriate dosimetry
models, which require knowledge of the annual average transuranium
element concentration in air, aerosol particle size distribution, and
solubility class of the specific radionuclides present. Apparatus and
procedures for the sampling and analysis of particulates in air are
available, but the accuracy and precision of measurements must be
verified prior to implementation of the guidance.
200
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Judgment should be exercised in the:desigri of an air sampling
program to ensure that air concentration levels are representive of
actual exposure conditions. Environmental measurements of airborne
particulates which bias the dose estimates by the collection of only
certain particle size ranges should be avoided, or a suitable
correction should be made. It is preferable that the particle size
distribution be experimentally measured for a specific site.
Reasonable values can be assumed based on analogies with similar sites
when projected lung dose rates are small compared to the Guidance
level. The solubility class of an aerosol can usually be determined
from the history of the contaminating event and the subsequent
environmental weathering mechanisms. Dose conversion factors for lung
dose rates that the Agency believes to be reasonable for the purpose
of implementation of the Guidance were presented in Annex III.
A derived air concentration "screening level" which if not
exceeded indicates with high probability that the guidance
recommendations will not be exceeded, may be substituted for a
site-specific air concentration limit. The agency suggests that such
a derived air concentration "screening level" be based on an activity
median aerodynamic particle diameter (AMAD) not to exceed 0.1 urn,
which is substantially smaller than observed values at all sites where
transuranium element contamination presently exists. The calculated
limiting concentration for this procedure would be about 1 fCi/m3 of
alpha emitting transuranium nuclides, for air samples averaged over a
period of one year or more. Air concentrations above this value do
not necessarily mean that the Guidance recommendations may be
exceeded, but rather this dictates that a more thorough evaluation of
existing conditions should be made.
Elevated levels of transuranium elements in air indicate that
these elements may be found in nearby soils. When these levels
approach that of the Guidance recommendation, implementation should
include a characterization of the environmental source term, to
provide a means of judgment with respect to the potential for future
exposure levels and the practicality of remedial measures.
5.2.2 Dose Rate to the Bone
Bone dose rates are calculated with appropriate dosimetry models
using a knowledge of the average amounts of transuranium elements that
are ingested in a year, their chemical state at the time of ingestion,
and the proper dose conversion factor. Inhalation of transuranium
elements, especially in soluble forms, can also lead to radiation
doses to bone and should be considered where appropriate.
Sampling and measurements of transuranium elements in food and
water at the point of human consumption is the most direct and
preferred procedure for determining the annual average ingested amount
201
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of these elements. Alternatively, the amounts of ingested
radionuclides may be estimated using environmental pathways models.
The chemical state at the time of ingestion is inferred from the
medium in which the transuranium elements are incorporated. In
particular, transuranium elements which are incorporated into
biological tissue should be considered as "organically complexed" and
require a special dose conversion factor. Dose conversion factors
that the Agency believes appropriate for the implementation of this
Guidance with respect to bone dose rates were given in Annex III.
Suitable sampling and analytical procedures are available for the
analysis of the transuranium elements in food and water. As with the
inhalation pathway, elevated levels of plutonium and the transuranium
elements in food or water indicate that these elements may be found in
nearby soil or in sediments. Under such conditions, implementation of
the Guidance should include .a characterization of the environmental
source term, to provide a means of judgment with respect to the
potential for future exposure levels and the practicality of remedial
measures.
5.3 Implementation of Guidance by Use of a Soil "Screening Level"
Federal agencies may show compliance for the total area of a
site, or for subareas of a site, by certifying that such areas have
transuranium element soil concentration levels less than a "screening
level" value of 0.2 uCi/m2. The "screening level" is a total
transuranium element soil concentration level in the top 1 cm of soil
such that, in the Agency's opinion, dose rates will not exceed
Guidance recommendations under the vast majority of land use
conditions. When this implementation mechanism is used, all lands
subject to unrestricted use must meet the screening level criteria.
Because of present uncertainties in the amount of plant uptake for the
more soluble transuranium nuclides, such as americium and curium, and
the resultant possibility of larger doses via the ingestion pathway
than calculated, the "screening level" concept may not be applicable
when the soils of a contaminated area contain these nuclides in
amounts greater than 20-25% of the total activity. Lands with
concentration levels less than the "screening level" are judged to be
suitable for all normal activities including residential and
agricultural uses. The use of this "screening level" is intended to
reduce the land areas requiring extensive evaluation and to minimize
the number of measurements needed.
If land areas have transuranium element levels greater than the
"screening level," it should not be presumed that Guidance values are
necessarily exceeded, because conservative assumptions were used in
the derivation. Additional site specific evaluations of potential
dose rates to lung and bone (Section 4) should be made before remedial
actions are initiated.
20 2
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Inherent in the application of the screening level is the
assumption that soil contamination by the transuranium elements will
cause radiation exposure through pathways such as the inhalation of
resuspended soil, the ingestion of foodstuffs grown on the soil-, the
ingestion of soil by children, and the ingestion of drinking water
contaminated by soil runoff. In all cases the cumulative doses to the
critical segment of the population must be considered, with the
admonition that the accumulated doses from all pathways should not
exceed those recommended in this Guidance. "
5.4 Implementation of Guidance by Means of Soil Data Using
Site-Specific Parameters
Federal agencies may show compliance with this guidance for a
specific site, or for subareas of a specific site, by means of soil
measurements and by using pathway and dosimetry models with parameters
determined for the specific site to certify that the resulting dose
rates do not exceed Guidance values. This approach differs from the
use of a soil "screening level" because parameters such as the
resuspension factor are determined for a specific site. It is
expected that use of site-specific parameters will show that soil
contamination levels higher than the suggested "screening level" may
correspond to organ doses well below Guidance levels. Implementation
by site-specific parameters is appropriate where land areas have
transuranium element levels greater than the "screening level" and
further evaluation is necessary to determine whether or not guidance
dose limits are being exceeded.
The air concentration where people are located generally can be
correlated with the adjacent soil concentration by use of a
resuspension factor, and can be used to estimate the inhalation dose
rate. The site-specific resuspension factor may be either measured
directly or calculated from other data. Direct experimental
determinations are often difficult to make and not always
reproducible. Therefore, calculational techniques are sometimes
preferred although their correlation with measured values is subject
to considerable uncertainty. The agency staff has developed a method,
based on the concept of air mass loading, which may be useful for this
purpose(see Annex II). An "effective" resuspension factor is derived,
defined as the resuspension factor derived from the air mass loading
for the given location and modified by a "distribution factor" which
takes into account the generally observed nonuniform distribution of
the activity with size of particles in calculating the amount of
transuranium element activity in the inhalable fraction of the
resuspended material. The "distribution factor" is a theoretically
derived parameter, and its correlation to actually observed situations
has not yet been established. The resuspension factor derived in this
manner is applicable only to extremely large areas sources, and must
be further corrected for the dilution by uncontaminated materials when
used for small contaminated areas.
-------
The ingestion pathway must be evaluated separately, using data
applicable to the specific site in terms of type of crops, plant
uptake parameters, and pathway to a critical segment of the
population. The more unusual transfer mechanisms to people, such as
the ingestion of dirt by children and the contamination of drinking
water sources, may also need to be examined if shown to be of
importance.
5.5 Sampling and Analysis Methods
Choice of Methods
The choice of suitable methods for sampling and analysis is the
reponsibility of the Agency implementing the Guidance. The
implementing Agency should demonstrate that the proposed methods have
the necessary sensitivity, accuracy, and precision. A description of
the apparatus and techniques used to collect the samples, the
procedures for preparing the samples for analysis, and the method used
for radiochemical analysis should be included.
Air Sampling
When air sampling is chosen as the principal method of
implementing the guidance, continuous monitoring should be performed
at locations indicative of potential doses to persons in the general
population. Aerosol collection efficiencies as a function of particle
size and other appropriate parameters must be reported for the
instruments and placements used. Results must be given in terms of an
annual average air concentration of transuranium elements at the
specified site.
Food Sampling
When foods are grown in contaminated soils, and the ingestion
pathway may represent a hazard to persons in a critical segment of the
population, representative samples should be obtained for analysis and
evaluation. Results should be reported in terms of activity per unit
of wet or dry weight, as appropriate, for specific food products and
for typical "market basket" averages for an individual.
Drinking Water Sampling
When soil or sediment analyses indicate the potential for the
presence of transuranium element contamination in drinking water
supplies, periodic monitoring should be performed. Results should be
reported in terms of activity per unit volume for both raw and
finished drinking water.
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Soil Sampling
When soil sampling is chosen as either the principal or ancillary
method of implementing the Guidance, statistically valid procedures
appropriate to the objective should'be used to characterize the entire
area known or suspected to be contaminated. When soil measurements
are made to evaluate the inhalation pathway, emphasis should be on
obtaining representative samples of surface soils subject to
resuspension and transport. In order to achieve a degree of
uniformity in application, the Agency recommends that soil samples be
taken to a depth of one centimeter and include all soil particles less
than, two millimeters.in size. Several individual samples may be
composited for a single measurement. At some sampling points it may
not be possible to collect samples to a depth of one centimeter e.g.,
very stony soil or a thick grassy area). In such cases, other means
must be found tor obtain representative samples.
For site-specific evaluations of resuspension parameters, it may
be necessary to determine the fraction of the total activity
associated with ranges of soil particle sizes (distribution factor).
Standard liquid or air sedimentation and separation techniques may be
used for this purpose. In general, soil characteristics should be
altered as little as possible in' the collection and preparation of the
soil sample and care should be taken to choose a method which does' not
cause the breaking up of soil aggregates that were present when the
sample was taken.
Radiochemical analysis techniques for the determination of ,
transuranium elements in soils are available and have been published.
These differ primarily in the method used to solubilize the plutonium
in the sample. Acid leaching, acid dissolution, and fusion are most
commonly used. The fusion method is considered to be applicable to a
wider variety of soils than the other two methods.
Alternative collection, separation, and analysis methods may be
used but must be adequately justified in terms of technical validity
and relationship of results obtained by the recommended method..
Statistical Criteria
The characterization of any large area in a cost-effective manner
requires that the sample locations be carefully determined in order to
optimize the information obtained. Statistical methods are available
to permit design of experiments to obtain results with the accuracy
and precision desired. ••'.,- ,
When planning a soil survey it is advisable to divide the total
area under investigation into units at the very begining of the survey
rather than to collect samples more or less haphazardly. Then samples
205
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taken to determine the acceptability of the land by.comparison of
measured concentration levels to the screening level may be collected
from sampling units in accordance with a sampling plan. If it is
later decided that more sampling is necessary, no change in the
sampling plan is necessary, and the location for additional samples
will have already been determined.
The number of samples to take within a sampling unit may be
estimated from the specific statistical approach used in the sampling
plan. An important factor affecting the number of samples to be taken
is the risk of making the wrong decision in deciding whether a
sampling unit is acceptable or requires remedial action. To reduce
the risk of making the wrong desision, larger numbers of samples must
be taken. Judgment must be used to strike a balance between the
desirability of making the right decision and the difficulties and
expense involved in taking large numbers of samples. An additional
factor affecting the number of samples is the variability of the
transuranium element concentration within a sampling unit. If
detailed information is not available on the variability, a simple
approach is to take the same number of samples within each unit.
These could be taken on a grid system to ensure that all subareas of
the sampling unit are sampled. A disadvantage of this approach is
that if the variability is substanially different in units, then the
probability of detecting concentration levels requiring remedial
action will vary from unit to unit. If estimates of variability are
available from past studies, these can be used to help determine the
number of samples required within each unit so that the probability of
making a correct decision will be the same for all units.
After soil concentration levels have been determined, it must be
decided if the area under consideration complies with the Guidance
recommendations or whether further evaluation will be needed. The
statistical methodology that is used must be such that few assumptions
regarding the form of the soil concentration distribution will be
necessary to ensure the validity of the statistical test. The method
should also ensure reasonably low bounds on the risk of making the
wrong decision, arid the probability of not accepting an area which
meets the guidance, or accepting one which does not, should be small.
Acceptance criteria which allow a maximum chance of error of 5-10% are
generally considered appropriate.
Considerable variation generally occurs in environmental samples
taken even in closely adjacent locations. If one or more samples from
any unit exceed the air or soil concentration limits corresponding to
the guidance recommendations, a decision must be made on whether the
sampling unit is acceptable. Such decision is best based on
statistical tests which consider both the magnitude of the deviations
from the average and the number of samples which are involved. A
number of statistical methods are available for performing such an
evaluation, and the choice must be made on the basis of the data
available and the results desired.
S06
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6. THE DOSE AND RISK TO HEALTH DUE TO THE
INHALATION AND INGESTION OF TRANSURANIUM HUCLIDES
6.1 Revised Risk Estimates For Leukemia
Due to a computational error, the leukemia risk estimates
published in Annex III of ths proposed guides (Pr 77) are too low.
While this has little effect on the estimated total risk due to the
inhalation of Class Y materials, it does affect the estimated lifetime
risk due to ingestion, as well as estimated risk due to the inhalation
of class W materials described in section 6.3 below.
Amended risk, estimates are given in Table 6.1.1. As before, all
risks ara based on lifetime exposure to 100,000 persons at the
proposed guidance limits: for inhalation, 1 mrad per year to pulmonary
tissue and for ingestion, 3 mrad per year to bone tissue in the 70th
year.
TABLE 6.1.1
New Leukemia Risks for Lifetime Exposure to Plutonium-239
Estimated Risk
Leukemia
New total Ca risk
Total risk estimated in Annex III
• Table A3-18
Cancer Deaths per 100,000 Exposed
Inhalation - Class Y Ingestion
1.2 9
10 1H
9* 5.6
The table above is based on a quality factor of 20 for alpha
particle irradiation, as stated in the guidance document. This choice
is based on ICRP Report No. 26, referenced in Annex III. More recent
information on the leukemia experience of Japanese atomic bomb
survivors than was available when Annex III was prepared, indicates
that a quality factor of twenty is not unduly conservative for
purposes of estimating risk of leukemia from high LET radiations.
Risk estimates based on the tissue dose rather than kerma exposure to
the Japanese survivors are discussed in Section 6.2 below.
6.2 Estimates of Leukemia Risk Based on Tissue Dose
The leukemia risks for high LET radiation, mainly proton recoils,
in the 1972 BEIR Report are based on "tissue kerma in air1*, i.e.,
attenuation of the dose by tissues overlying the bone marrow was
neglected. Recently, T. Ishimaru, M. Otake, and M. Ichiraaru have
reviewed the dose response pattern for the Japanese survivors in terms
207-
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of the calculated dose to bone marrow (Is 77). This was made possible
by detailed information on the gamma ray and neutron doses to bone
marrow developed by the Oak Ridge National Laboratory subsequent to
the BEIR Report (Jo 76). These results indicate that the proton dose
to marrow was only 26 percent of the tissue kerma in air, an
appreciable difference. Moreover, use of tissue dose for high LET
particles allows leukemia risks to be estimated directly (i.e., per
unit rad), rather than by means of an arbitrary quality factor based
on a number of end points. Except for leukemia, direct calculations
of risk per rad were used throughout Annex III to calculate somatic
risk. Therefore, use of such a direct approach should make the
estimates of leukemia risk more comparable to that for other cancers.
It should be noted that the linear energy transfer (LET) for 5 MeV
alpha particles from the decay of transuranium nuclides is nearly the
same as for one MeV recoil protons.
In their review of risk to Japanese survivors, Ishimaru et al.
fitted various dose responsive functions to the leukemia incidence
data to account for both the gamma-ray and neutron dose. For the
gamma-ray dose, linear, parabolic, and quadratic responses were
examined in combination with a linear response for the high LET recoil
dose. Use of these various models resulted in little difference in
the calculated risk for neutrons, 23-28 cases per million rad person
years at risk. Although there is no statistically significant
difference between these two estimates, the former number, based on a
linear response for both neutron and gamma radiation, is utilized
below.
Unlike the 1972 BEIR Report, the results cited above on the
leukemia risk due to neutrons does not consider children of less than
ten years of age as a separate population at risk. Rather, the
analysis is based on all ages. This should not be a serious source of
bias since the proportions of persons under ten among the Japanese
survivors is not too different from that in a stationary population.
Moreover, exposures during childhood contribute only two to ten
percent of the total number of excess leukemia cases resulting from
lifetime exposures to transuranics.
Input parameters for the leukemia risk estimates are listed in
Table 6.2.1, the selection of plateau period and duration of the
latent period are based on the 1972 BEIR Report (Na 72). The relative
risk coefficient is based on the regression results for bone marrow
neutron dose given for Model I by Ishimaru et al^, (Is 77).
208
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Table 6.2.1
Parameters for Leukemia Risk Estimates
High LET Particle Dose to Bone Marrow
Latent Period
(Years)
Plateau Period
(Years)
25
Absolute Risk
Death per
RPY*
23
Relative Risk
% increase in
deaths per rad
70$
*Rad x person years at risk
- ' •• . i
Table 6.2.2 compares the average of relative and absolute risk
estimates made with these parameters to those listed in Table 6.1 for
plutonium-239 ingestion.
Table 6.2.2
Leukemia Risk for Lifetime Exposure
Per 100,000 Persons - Bone Tissue Limit
3 mrem Per Year in the 70th Year
Basis for Calculation
Quality factor of 20, Table 6.1.1
Japanese Survivors, Table 6.2.1
Estimated Deaths
6.3 Dose Rates and Estimated Risks Due to Inhaled Class W Compounds
6.3.1 Introduction
The ICRP Task Group Lung Model (Ta 66, In 72) classifies inhaled
aerosols into three groups depending on the length of time they are
retained in the lung. Class Y compounds are retained for years, Class
W for weeks, and Class D for days. The retention times are largely
controlled by the solubility of the inhaled material in body fluids.
In the * technical document (Annex III) for the proposed guidance
(Pr 77), it was assumed that respirable materials which persisted in
the environment would most likely be insoluble oxides-and hydroxides
and therefore be Class Y materials. However, there is some evidence
from animal experiments that high specific activity plutonium oxides
such as 238puc-2 are more soluble than the long half life
transuranics and should be considered Class W compounds. Moreover»
other transuranics, such as americium-24l and curium-244 may in some
cases be in a chemical form that leads to Class W behavior. The
purpose of this section is to examine the dose due to. the inhalation
209
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of Class W transuranium aerosols and the estimated risks from such
exposures. It should be noted that solubility as a function of size is
not considered by the ICRP Task Group Lung Model. In practice, higher
solubility for sub-micron aerosols is likely to occur; therefore, the
estimated risk due to compounds more soluble than Class Y materials is
also of interest for this reason.
6.3.2 Application of the Proposed Guidance to Class W Transuranium
Compounds
The proposed guidance places two limitations on the alpha particle
dose rate to exposed persons: a maximum dose rate of 1 mrad per year;
to pulmonary lung tissues and a maximum dose rate of 3 mrad per year to
bone tissue after a 70-year (lifetime) exposure. In both cases the
alpha energy is averaged over the total tissue mass (Pr 77). Because
of their shorter residence time in lung tissues, inhaled Class W
transuranics result in a relatively small lung dose compared to that
received by other organs due to the translocation and deposition of
dissolved material. Therefore, the dose rate to bone tissue becomes
limiting, not the dose rate to pulmonary lung.
Table 6.3.1 lists the air concentrations of Class W transuranium
radionuclides that result in an average bone alpha dose of 3 mrad per
year after 70 years of exposure. The potential risks due to inhalation
of Class W transuranics are not confined to bone cancer but include
leukemia and cancer of the liver and lung as well as genetic effects,
see Section 6.3-4 below.
TABLE 6.3.1
i
Aerosol Concentrations 'in fCi/m3 Producing a 3 mrad
Annual Skeletal Dose Rate in the 70th Year Following Lifetime
Inhalation by Reference Man - Class W Solubility
Size
(AMAD)
0.05
0.10
0.30
0.50
1.0
2.0
3.0
5.0
238Pu
94
5.7
6.4
7.6
7.8
7.8
7.2
6.7
6.4
239Pu
94
4.8
5.3
6.3
6.5
6.5
6.0
5.6
5.4
24lPu«
94
200
220
260
270
270
250
240
230
95
4.7
5.3
6.3
6.4
6.4
6.0
5.5
5.3
244Cm
96
11
12
14
15
15
14
13
12
•Only alpha dose rate due to the Am-241 daughter is considered in
assessing limit
210
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For most transuranic materials (the exception is Plutonium-241)
the limiting concentration in air of a Class W material is greater than
that, for a Class Y material containing the-same radionuclide.-
This difference is as much as a factor of five or more for the smallest
particle sizes, considered in Table 6.3.1, c.f. Table 6.3.1 with Table
A-3-4 in Annex 111(3). For 1 micron AMAD particles the limiting
concentration of Class W compounds is about 3 times greater than for Y
compounds.,; For this reason, there must be reasonable assurance jthat
the inhaled material is in the form of a Class W compound before" Table
6.3.1 is used to establish compliance with the proposed guides. When a
mixture of Class Y and W compounds are inhaled, compliance should be
based on the limiting concentration for Class Y materials unless the
proportion of each type of pollutant has. been fully established.
Plutonium-241 is an obvious exception since the limiting concentration
is up to 8 times less for a Class W than for a Class Y material.
6.3.3 Alpha Particle Dose Rates from Inhaled W Aerosols .
The annual dose rates following 70 years of inhalation exposure to
several transuranium radionuclides in the W form are listed in Table
6.3-2 for 1 micron (AMAD) particles. More than 99 percent of the
equilibrium dose rate to pulmonary lung tissue is achieved after five
years of exposure. For other organs the dose rate increases with the
duration of exposure. It is recognized that lifetime .exposure to a
constant concentration of curium-244 aerosols is unlikely because of ,
its relatively short half life (17 years).
TABLE 6.3.2
Annual Dose Rates to Various Organs of Reference-Man Following
Chronic Lifetime Exposure to Class W Transuranium Aerosols
Concentration 1 fCi/m3; Particle Size 1 micron (AMAD)
Equilb. Dose
Radionuclide Pulmonary
-
Pu-238
Pu-239
Pu-241
Am-24l
Cm-244
Lung
41
39
0.04
41
44
Rate (microrad/y)
Tracheobronohial
Lung
16
15
0.01
15
17
Dose rate in the
70th yr (microrad/y)
Bone Liver
390 810
460 930
10 20
470 960
200 460
Bone Marrow
340
400
9
410
180
Effective biological half lives and removal pathways for lung
deposited Class W compounds are described quantitatively in (Su 77),
along with the description of the analytical techniques used in the
211
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preparation of Table 6.3.2. As was the case for Class Y materials,
eight particle sizes (AMAD) were considered in these calculations. The
variation of dose rate with particle size of Class W particles is shown
in Table 6.3-3. Unlike the case of Class Y particles, a broad minimum
dose rate to liver and bone is observed for aerosols of between 0.3 and
1 micron (AMAD). The variation in pulmonary dose with particle size is
the same as for Class Y compounds.
TABLE 6.3-3
Variation with Particle Size of the Dose Rate to
Pulmonary Lung, Bone and Liver for Inhaled Class W Aerosols
(Lifetime Inhalation at a Constant Concentration)
Particle Size
AMAD (Microns)
0.05
0.10
0.30
0.50
1,
2,
3.
5,
00
00
00
00
Equilibrium Lung
Dose Rate Ratios*
2.6
2.2
1.6
1.4
1.0
0.7
0.6
0.5
Dose Rate Ratios*
for Bone and Liver
in the 70th Year
1.1
1.2
.0
.0
1.
1.
1.0
1.1
1.2
1.2
•Normalized to 1 micron (AMAD)
6.3-^ Health Risk Estimates for Class W Transuranios
The inhalation of Class W compounds results in both somatic and
genetic risks. Although the limiting dose rate for inhaled Class W
compounds is in terms of the dose to bone, the dose to lung tissue is
not negligible. The estimated risk of lung cancer is about the same as
the estimated risk of leukemia, liver or bone cancer. The genetic risk
for inhaled Class W transuranium materials is larger than for inhaled
Class Y aerosols, being nearly the same as the genetic risk for
ingestion listed in Annex III (Pr 77).
The methodology for estimating somatic and genetic risks due to
the inhalation of transuranics is discussed in Annex III (Pr 77). Like
the case for transuranium ingestion, where the dose rate limitation for
bone tissue is also 3 mrad per year, the 30-year gonadal dose for most
inhaled Class W transuranium compounds is about 10-12 mrad, i.e.,
calculations of 30-year gonadal dose for Class W yielded results
identical to those listed in Table A3-15 of Annex III (Pr 77).
212
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Therefore, the estimated genetic risks for Class W inhalation are the
same as listed in Table A3-16 (Pr 77) for the ingestion pathway.
Estimated somatic (cancer) risk following inhalation of Class W
are listed in Table 6.3.4 below. The assumptions made in the
calculations of these risk estimates are the same as made for Y
compounds in Annex III except that, a quality factor of 20 was used for
leukemogenesis.
TABLE 6.3.1*
Estimated Risk of Cancer Due to a Lifetime Inhalation Pattern That
Results in a 3Mrad Per Year Alpha Particle Dose Rate to Bone in
the 70th Year - Number of Deaths per 100,000 Persons
Class W Aerosols
Cause of Early Death
Lung cancer
Bone Cancer
Liver Cancer
Leukemia
TOTAL,
Pu-238
b 2.6
2.6
2.2
9.2
17
Radionuclide
Pu-239 Pu-241
2.1
2.U
1.9
8.8
15
0.11
11
6.i» Transfer of Transuranium Material to Blood From the GI Tract,
In the course of reviewing the literature on. transuranium elements
while preparing "Proposed Guidance on Dose Limits for Persons Exposed
to Transuranium Elements in the General Environment'1, the staff was
concfpned about using truly appropriate gut transfer factors for the
transuraniuin isotopes. While ICRP Report f19 recommends a gut transfer
factor pf 1 part per 10^ for "relatively insoluble material, such as
PuQ2nt transfer fractions of the order of 10~2 to 10"* are not
unCQpimon in more cpntempoj-ary reports (S\t 75, Su76, Pi 76, Br 75). In
view of these reports of higher gut transfer"factors, the staff took
advantage ol an ERDA offer of aid from their contract laboratories.
Th§ letter containing EPA proposed gut transfer factors circulated to
ERDA investigators considered knowledgeable in this field is reproduced
below.
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13 DEC 1376
Dr. William J. Eair
Director, Life Sciences Program
Pacific Northwest Laboratories
Battello Memorial Institute
Rlchland, Washington
Dear Billt
In the hope of trying to reach accord with ERDA on the doalnetrlc
parameters used by. EPA in developing guidance for plutoniun In soils, we
«r« asking several ERDA investigators for relevant consents*
. Heal Kelson has prepared a table of provisional gut transfer frac-
tions for transuranic isotopes, enclosed. The data is derived prlnarily
from ERDA's BSHL presentation at the EPA hearings in Washington (WASH-
1539) and from the 1975 BHKL Annual Report, BSWL-200C-PTI (Sullivan and
Crosby). Since theaa reports reflect, for the roost part, observations
On rate, some consideration was also given to Battelle data on swine
CBNHL-280) and Suldakov, et al.'e data on dogs.*
Tour connenta on whether these gut transfer factors seera reasonable
Or not, and any codifications you would suggest, based on your own
Interpretation of the Battelle or other data, would be appreciated.
•L. A. Buldalcbv, B. R. Lyubchanokii, Yu. I. Koskalev and A. P. Hitatov,
Frobletua of Plutonium Toxicology, LF-tr-41, 1970.
•214
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2
Zf possible, we vould like your eonments before Christmaa as
Vd ftrs trying to complete a new draft, not a redraft, on doee and effects.
Siffica the nails are bad, perhaps you would phone Neal or me (202-755-3852)
after you have reflected OB the proposed numbers.
Slaeerely yours.
W. E. Ellett, Ph.D.
Chief, Bioeffects Analysis Branch
Criteria & Standards Division (AN-460)
Office of Radiation Programs
.osura
e Chester Riehnond, Oak Ridge Rational Laboratory
Dre Roy Thompson, Battelle Northwest Laboratory
Ite, John Marshall, Argoane National Laboratory
AH-460/NSNelson/mlb 12/10/76 WSMIE; 629, ext 5,3852
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Provisional Gut Transfer Fractions
. for Transuranic Elements
Isotope
Np+5 soluble
oxide
biologically incorporated
238Pu*4 soluble
oxide
biologically incorporated
239Pu*4 soluble
oxide
biologically incorporated
Am soluble
oxide
biologically incorporated
Cm*3 soluble
oxide
biologically incorporated
Bk, Cf, Es soluble
oxide
biologically incorporated
Infant (0-1 yr)
7 x 10
,-2
2 x 10"
5 x 10
,-4
4 x 10
2 x 10
f3
,-4
9 x 10
,-2
5 x 10
,-3
6 x 10
10"
4 x 10
,-2
,-2
Child (> 1-9 yr)
10
,-2
10
,-3
3 x 10
2 x 10"
3 x 10"
2 x 10"
,-4
,-6
10
5 x 10"
10
10
10
,-4
,-3
5 x 10
,-4
Adult (> 10 yr)
10
,-2
r3
10
3 x 10'
2 x 10
3 x 10
r4
,-3
2 x 10
lO'6
5 x 10"
1C'4
10"3
10~4
5 x 10
,-4
,-4
[Estimates based on Battelle rat and pig data and Russian dog data.]
-------
Scientists at Battelle Pacific Northwest Laboratories considered
the question in some detail and simplified the age specific table of
gut transfer factors proposed in the EPA letter. Their response is
reprinted below. It acknowledges both the uncertainty and conservatism
in these estimates, a conservatism necessitated by the extrapolations
from animals to man.
The EPA staff used the estimates provided by BPNL scientists as
prudent values for protection of public health in their development of
the Guidance for Transuranium Elements.
Responses from other ERDA investigators were of a non-numerical
character and not directly applicable to the problem.
217
-------
February 1, 1977
IIBalielle
l.uilK Noii|i,v(>sl l.ihni.ilniir
ll.lllcllf Hoillcv.iirl
K» M m«l, W.iOiutfM
946-2421
».' «. tr.
Dr. W. H. Ellett
Dr. N. S. Nelson '
Criteria and Standards Division - ORP
Environmental Protection Agency
Waterside Mall - 629E
4th & M Streets SW
Washington, D.C. 20460 :
Dear Bill and Neal:
We have had extensive discussions with several scientists in the Biology and
Ecosystems Departments concerning your need for gut transfer numbers. As you are
well aware, this is an area of current active investigation and everyone would
rather have a few more years to get better answers. But we recognize your
problem and will attempt in this letter to give our best advice,'emphasizing that
it is an interim appraisal, almost certainly erring on the conservative side, and,
of course, subject to future revision.
We will make no attempt in this letter to review the data. You are as aware of
most of this data as we are—as evidenced by the extensive compilation of numbers
enclosed in your recent letter. One of our objectives has been to reduce the
complexity of that table, since we feel that it implies a great deal more confidence
in small differences- than we are entitled to have. We are all aware of the many
uncertainties involved in the measurement of these .numbers and in their extraoolation
from animals to man.
The numbers we would recommend for all transuranics are the following, expressed
as fraction absorbed to blood: •
Child and Adult (>_ 1 year): 10
-4
except: 10 n for
Infant (< 1 year): 10" ]
-4 23Q "?
except: 10 n for 03Pu02, 5 x 10 for biologically incorporated transur
except: 10
-2
for 239PuO,
This amounts to choosing a single basic value of 10 , to which v/e make 3 exceptions
a factor of 10 decrease for 239pUQ2, a factor of 5 increase for biological incorpor-
ation, and a factor of 100 increase for the infant to age 1 year.
Our basic factor of 10~ is conservative, but this seems justified in view of the
uncertainty involved in extrapolation to the human. It is undoubtedly more
conservative for plutonium than for the transplutonium elements, and not conservative
for neptunium, but this seems reasonable in view of the relative significance of
these various elements as possible environmental contaminants.
218
-------
Drs. W. H. Ellet.t. and
N. S. Helsorv
February 2, 1977
239,
Because of the abundance of data showing a much lower absorption for Pu02,
and because of the importance of this compound, an exception seemed justified.
A fiqure of 1(TS might well be justified from animal data, but again^we felt
that in view of the uncertainties in extrapolation to man, conservatism was
in order.
The factor of 5 for biological incorporation is based on very limited, and not
always consistent, results .from experiments in progress, in which rats and guinea,
pigs were fed alfalfa that contained biologically incorporated plutom,um. We
may have a better basis for this number within a few months.
Without doubt the greatest uncertainty attaches to the number chosen for the
infant, and to the time period assigned to infancy. The factor of 100 seems to
be a maximum enhancement factor, based on the data ava Table. There is; Decrease
in this enhanced absorption with age, but no clear basis-far^extrapolating this
decrease to man. Depending on your.assumed theory for :explaimng^the enhanced.
absorption you can argue for a period of a few days, or for a^much longer period-
We feel that assumina a high enhancement value of 100, without decrease over the
first year .of,life, Is a .conservative approach. Rather than i.sting an absorption
factor of10-1, for which the evidence is so indirect, we would prefer to use.-the ..
adult factor in all calculations and then apply a lifetime "correction factor of
2 to account for possibly enhanced absorption during infancy, thus stating no
specific increase and no specific period during which it applies.
We-have, applied the factor of 10 reduction for 239Pu02 to the infant because of
the substantial amount of data showing that transuranic oxides are less well
absorbed by very young animals than, are ol-her compound forms.
We have not applied the biological incorporation factor to the infant, primarily
because it would involve multiplying three, conservatively chose,n numbers, to arrive
at a prediction of 50% absorption, which seems quite unreasonable. On more .
scientific grounds, one can argue that the mechanisms for enhanced absorption_due
to infancy and due to biological incorporation are_most likely totally unrelated
and therefore not multiplicative in their application.
We hope that this effort has been helpful. There are no easy answers.
keep you informed of any new developments in our research in this area;
be glad to respond to any further questions that you might have.
Sine
We will
and would
W. d. Bair, Ph.D.
Manager >
Environmental & Safety
. Research Program
RCT:WJB:ms
R. C. Thompson, Ph.D.
Senior Staff Scientist
Biology Department
T O
-------
In 72
Is 77
Jo 76
Pr 77
Su 77
Ta 66
REFERENCES
International Commission on Radiological Protection Publication
19, 1972. The Metabolism of Compounds of Plutonium and Other
Actinides. Pergamon Press, New York.~~
Ishimaru, T., M. Otake and M. Ichimaru, Incidence of Leukemia
Among Atomic Bomb Survivors in Relation to Neutron and Gamma
Dose, Hiroshima and Nagasaki 1950-71, RERF Technical Report
Series, TR 14-77, Sept. 15, 1977. Printed March 1978.
Jones, T.D., Radiation Insult to the Active Bone Marrow as
Predicted by a Method of CHORDS, ORNL Report ORNL/TM-5337,
1976.
Proposed Guidance on Dose Limits for Persons Exposed to
Transuranium Elements in the General Environment, 1977.
EPA 520/4-77-016, U.S. Environmental Protection Agency,
Washington, D.C. 1976.
Sullivan, R., 1977. Plutonium Air Inhalation Dose (PAID).
ORP/CSD Technical Note 77-4, U.S. Environmental Protection
Agency, Washington, D.C. 20460.
Task Group on Lung Dynamics (TGLD) 1966. Deposition and
Retention Models for Internal Dosimetry of the Human
Respiratory Tract, Health Physics 12:173-208.
220
-------
7. Rocky Flats Facility/Technical Assessment Document
7.1. Introduction
The purpose of this report is to present an analysis of the potential
hazards to individuals in the general population as a result of present
levels of the transuranium elements existing in the environs of the DOE
.,Rocky Flats Plant. The various pathways by which exposures might occur
under present and projected land usages are examined and interpreted in
light of EPA's proposed guidelines for exposures to the transuranium
elements.
7.2 Inhalation Pathway
7.2.1 Ambient Air Concentrations
Under normal operating conditions, minute quantities of plutonium
and other radionuclides are released per year to the atmosphere from the
Rocky Flats Plant. These releases are of small magnitude and originate
from the plant's ventilation and filtration system. In addition to
continuously monitoring the effluent air from production and research,
facilities, the Rocky Flats facility maintains a system of high-volume
ambient air samplers within the plant boundary, at off-site locations in
the immediate vicinity of the plant, and in several nearby communities.
Altogether the system comprises 21 air samplers operating continuously
within and on the perimeter of the Rocky Flats security area, and another
25 samplers located at various distances and directions from the plant.
The data from this network are reported on a monthly basis to the Rocky
Flats Area Office of DOE, the Division of Occupational and Radiological
221
-------
Health of the Colorado Department of Health, the Denver Regional Office
of the EPA, the Health Departments of Boulder and Jefferson Counties,
and city officials in several communities near the plant.
In addition to the surveillance network maintained by the Rocky
Flats Plant, the Health and Safety Laboratory (HASL) of DOE has con-
ducted a program of continuous air sampling for plutonium at the Plant
since June 1970 in response to the discovery of elevated levels of
plutonium found in soils at location which were then off-site. The HASL
network consists of four sampling locations (Figure 7.1), three 6f which
are downwind (east) from the original location of the oil drum storage
site and the fourth air sampler is located off-site and upwind from the
Rocky Flats Plant (2). Air concentration data in attocuries of Pu-239
per cubic meter of air (aCi/m3)*, as reported by this network on a
monthly basis from June 1970 to March 1976, are given in Table 7.1. A
significant downward trend with time can be seen in the level of plutonium
in air at the stations downwind from the plant. It has been suggested
by HASL that this downward trend is attributable to the weathering of
the contaminated soil in the on-site vicinity of the original oil drum
storage site. This weathering may be due to the movement of the plu-
tonium from the surface down into the soil, as well as changes in the
characteristics of the plutonium remaining on the surface. In addition
to showing a decrease with time, the data indicate a decrease in con-
centration with increasing distance downwind from the site of the
original spill area. Based upon air and soil sampling, as well as the
direction of the prevailing winds around Rocky Flats, HASL concluded in
1972 (3)
*1 attocurie = 10~ curie
eynr
'
-------
ro
RT.72
;.'• \
I PLANT SITE
» EAST GATE
SPILL AREA
V
Vs
T. WESTERN
RESERVOIR
t=t
MILES
MAP OF ROCKY FLATS PLANT AND VICINITY
INDICATING CONTINUOUS AIR SAMPLING SITES
FIGURE 7.1
;3
«
-------
that the original spill area was the primary source of plutonium in the
Rocky Flats environment.
Levels of airborne plutonium at the downwind edge of the facility's
buffer zone (Indiana Street) are approximately the same as reported for
the monitoring station upwind from the plant. Although these levels are
about twice those expected from background radioactivity in the Rocky
Flats area, the effect of the spill area upon the off-site environment
has been much reduced from earlier levels.
Comparison of the most recent HASL data (1976) for the Indiana
Street location (site 2) with the 1975 data reported by the Rocky Flats
Plant (Table 7.2) for the same' general area shows the two networks to
agree within a factor of about 2. The values reported by HASL range
'3
between 12 to 23 aCi/m , while Rocky Flats reported an average of 37
aCi/m3.
7.2.2 Calculation of Inhalation Doses Due to On-Site Contamination
An assessment has been made of the potential inhalation dose which
could be received by individuals residing off-site of the Rocky Flats
Plant. In carrying out this assessment, a deliberate effort has been
made to choose assumptions which are conservative, i.e., likely to
result in an overestimate of the actual dose. These are:
a) Inhaled plutonium is considered to be in an insoluble form.
(Chemical solubility of an aerosol determines its residence time in the
lung, with insoluble compounds being retained the longest.)
£a (rt \ti
-------
b) The plutonium aerosol is assumed to have a lognormal distribution
with an activity.median aerodynamic diameter (AMAD) of 1 micrometer.
(According to the ICRP (4) this implies that approximately 25% of the
aerosol will be deposited in the pulmonary compartment of the lung.
HASL ,.(5)i has reported 25% of the airborne activity being in the respirable
range- around Rocky Flats, while Sehmel (6) has reported a 20% respirable
fraction).. ' ... .
c) The individual is considered to be- exposed continuously for 70
years at the currently observed air concentration. (No further reduction
in airborne activity as a result of weathering or remedial actions is
assumed.)
d) All plutonium measured was assumed to originate from on-site,
with no correction being made for ambient background levels of plutonium.
The PAID code developed,by EPA (7) was used to-calculate the annual
dose rate. This computer code is based upon the ICRP Task Group Lung
Model (4) and calculates dose rates to various body organs as a consequence
of inhaling transuranic material. Tables 7.3 and 7.4 have been generated
by the PAID code and relate years of exposure to the resultant dose rate
for various, organs. Values in the tables are normalized to an aerosol
3
concentration of 1.0 femtocurie per cubic meter of air (fCi/m )* with a
1 ym AMAD. •
Indiana Street Location
Indiana Street is the nearest location.tp.the ,Rocky Flats Plant
where an individual in.the general population could be exposed as a
result of transuranium contamination originating from the Plant. This
location is in the downwind direction of the prevailing winds that blow
across the Rocky Flats Plant and, therefore, would represent a worst
case for offsite exposure.
es _
225
* 1 femtocurie =10 curie.
-------
From Figure 7.2 it can be seen that stations S-35, S-36, S-37, S-38, and
S-39 are located along Indiana Street. Station S-37 reported the highest
annual average for 1975 of 0.056 .fCi/m3 (Table,7.2). Assuming this
level to continue for the next 70 years, the 70th year dose rates to
lung and bone can be calculated.
o
According to Table 7.3, an air concentration of 1.0 fCi/m for 1 ym
AMAD aerosols of Pu-239 would produce a 70th year dose rate to the
pulmonary compartment of 0.38 mrad/yr; therefore, proportionally, a
concentration of 0.056 fCi/m3 (S-37) will produce a 70th year dose rate
of 0.02 mrad/yr. The bone dose rate associated with this level of Pu-
239 according to Table 7.4 will be 0.009 mrad/yr in the 70th year.
Data on the air concentration of Am-241 have been reported by HASL
(2) for the years 1970 through 1974. These data show the americium
levels, measured at the perimeter fence ,of the'Plant, to be approximately
11% of the Pu-239 levels. HASL has also projected that the Am-241
activity level will reach its maximum value arising from the decay of
Pu-241 in the year 2033, at which time it will amount to 18% of the Pu-
239 activity. For the calculation of the dose rate from Am-241, it is
assumed that'Am-241 is at the maximum of 18% of the Pu-239. The 70th
year dose rate corresponding to a concentration of 1 fCi/m3 of Am-241 is
0.4 mrad/yr; proportionally, an air concentration of (0.18) (0.056
3
fCi/m ) would produce 0.004 mrad/yr to the pulmonary compartment. The
associated bone dose would be approximately 0.002 mrad/yr.
Based upon these calculations, the total pulmonary dose rate after
70 years of exposure for an individual living along Indiana Street
226
-------
FIGURE ;7.2
J ' - " „ , , . ,"""'' "'-'«"
LOCATION OF
OFF-SITE AMBIENT AIR SAMPLERS
COAL CREEK
O ©SUPERIOR
MARSHALL
IN
S-32
0]BROOMFIELD
©WALNUT CREEK
LEGEND
O ON-SITE AIR SAMPLERS
A AIR SAMPLERS, 3 TO 6 KILOMETERS ( 2 TO 4 MILES) DISTANCE
© COMMUNITY AIR SAMPLERS ' .
227
-------
would be 0.024 mrad/yr, while the associated bone dose would be 0.01
mrad/yr. These dose rates are approximately 2.5% and 0.3% respectively
of the lung and bone dose rates recommended as guides by EPA (1).
Individuals living further away from the Rocky Flats Plant should
receive even lower doses than these due to the lower air concentrations
reported for the nearby communities. Based upon the preceding analysis,
the direct impact of the onsite contamination upon the off-site environ-
ment can be judged to be small and well within the EPA guidance limits.
7.2.3 Calculation of Inhalation Doses Due to Off-site Contamination
A complete assessment of the inhalation pathway for the Rocky Flats
vicinity must also consider the potential hazard from the low levels of
contaminated soil which already exist off-site. Questions have been
raised as to the effect of this material in producing localized exposures
which are not necessarily reflected in the data obtained through, the air
monitoring network around Rocky Flats. These inhalation exposures can
arise through various mechanisms including: wind resuspension of con-
taminated soil, vehicular and mechanical disturbances of soil, accumu-
lation and resuspension of dust within the home, as well as the resuspension
of contaminated soil attached to clothing. The following analysis will
attempt to investigate these exposure mechanisms and assess their potential
impact.
Wind Resuspension
Figure 7.3 shows the off-site soil contamination contours reported
by HASL in 1970 (3). More recent soil sampling programs in 1975 (9)
have not shown these contours to have changed significantly from the
1970
22B
-------
ROCKY / //^
I FLATS /' //
IPLANT / //
ERDA PRO? = * I r s '-. '•
BOUNDARY O.\ \
^_n -^
FI G U R E1.3 Plutonium-239 Contours Around Rocky Flats (pCi/rrr)
(adapted from FCrey, 1970)
990
4^4 &/ VJ*
-------
10
report. The highest off-site contour shown by the HASL data is 0.05
2
yCi/m . These contours were developed based upon an inventory sample to
a depth of 20 centimeters. What is important in assessing the resuspension
of soil, however, is only the material existing near the surface. In
the derivation of EPA's guidance (1), the layer subject to erosion was
considered to be the top one centimeter. Based upon the HASL soil depth
profiles, Anspaugh (10) has estimated that approximately 20% of the
total activity is contained within this first centimeter1 Therefore,
2 2
the highest contour value of 0.05 uCi/m would correspond to 0.01 iaCi/m
2
when corrected for a 1 cm. depth. On a mass basis, 0.01 yCi/m is
equivalent to approximately 2 disintegrations per minute per gram of
soil, i.e., 2 DPM/gm. The off-site area bounded by this contour is
approximately two square kilometers and soil within sthat area would be
projected to be at or above 2 DPM/gm. Beyond this area, off-site soil
will generally be below this value.
In developing its guidance to other Federal agencies on environmental
levels of the transuranium elements, EPA used the mass loading approach
as an indicator of the general resuspension by wind over large land
areas. Because of technical shortcomings identified with the mass
loading approach, the agency staff modified the concept to assess small
areas of contamination (area correction factor) and.to reflect a nonuniform
distribution of radioactivity with soil particle size (enrichment factor).
This latter modification is particularly important because transuranium
activity associated with soil particles within the respirable range is a
greater hazard than it would be if associated with' the larger nonrespirable
particle sizes. ,
230
-------
11
The mass loading approach assumes the loading of the air with
particulates to be an index of resuspension and derives the airborne
concentration of a specific radionuclide by a comparison with its
concentration on the adjacent surface (11). Specifically,
Air Concentration (fCi/ 3) = Soil Concentration (U 1/m ) x
.' - .,....-. m ' • ' . •„-.••- '.,'
Mass Loading (ys/m3) x U.C.*
Eq. 1.
Airborne pafticulate mass loading is one of the criteria for clean
air standards, and measurements are widely available for urban'arid
nonurban locations through"the National Air Surveillance Netwdirk (NASN).
The data recorded at nonurban stations are a better indicator of the
levels of resuspended material than are urban measurements1 In general,
annual mean mass concentrations of airborne pafticulate material at the
nonurban stations range from 5—50 micrbgrams per cubic meter"(Figure '
7.4); the mean arithmetic average for 1966 of all 30 nonurban NASN
. 3 .. . • • -, .. ..-,:•;.-
stations was 38 yg/m (11). From Figure 7.4 an estimate can be"made'of '
the average mass loading for the general area in which Rocky Flats is"
3 . . .
located and it would appear that 15 Jig/m is reasonably representative
of this area on an annual basis.
Simple application of the mass loading approach without corisid-
deration of the activity distribution as a function of particle s±zeis
not appropriate, however, since that would imply a uniform distribution
of activity with particle size as well as a uniform - •
*Where U.C. is the units conversion factor based upon the depth of
sampling and the soil density.
231
-------
12
ANNUAL aiEAPi E1ASS CONCENTRATIONS (^jg/ni3) OF AIRBORNE
PARTICLES FRQivl NON-URBAN STATIONS OF THE U.S. NATIONAL
AIR SA&V1PLJHG NETWORK. 1964 - 1965
FIGURE 7.4
232
-------
13
resuspension of all particle sizes.- This has-not been found to be the
case at Rocky Flats (12,13) or at other plutonium contaminated sites
(14). In addition, an important consideration in assessing the potential
exposure due to contaminated soil is the amount of activity associated
with particles within the respirable size range. Johnson (15) has
suggested that sampling of only those particles in a soil sample which
are within the inhalable size range (generally < 10 ym) would give the
best measure of risk to the public health around Rocky Flats. However,
the weight fraction of particles in the less than 10 ym range is small
in most soils, and sampling, separation, and analysis techniques are..
correspondingly more difficult and inaccurate. Also, a substantial
contribution to other possible pathways (e.g. ingestion) may be via
larger particle sizes and measurement of the contribution of only the
inhalable fraction would not provide all the information that is required.
In order to adequately assess the potential hazard of the inhalable
fraction of soils, while retaining the advantages and convenience of
analyzing the entire soil sample, the agency staff modified the mass :
loading approach by use of an "enrichment factor". While such a concept •
does not have universal acceptance, and the scope of its applicability
has not yet been determined, the agency.'staff believes that it represents
a useful method for the purpose intended and it has therefore been used
in this evaluation.
-------
14
Enrichment Factor
The "Enrichment Factor" is intended to 1) give a mathematical view
of the different fractions of the total radioactivity associated with
particles of different size ranges, and 2) address the problem of the
nonuniform resuspension of particle sizes.
The inhalable fraction of the soil is weighted by considering the
relative distribution of activity and soil mass as a function of particle
size for representative samples of soil. To accomplish this, the sample
of contaminated soil is segregated into "n" size increments and the
activity and mass contained within each size increment is determined.
The factor g, is then defined as the ratio of the fraction of the total
activity contained within an increment "i" to the fraction of the total
mass contained within that increment. A value greater than 1 for g±
implies an enrichment of activity in relation to mass, while a value
less than 1 indicates a dilution of the activity with respect to mass.
For g. equal to 1, the fractions of the activity and of the total mass
contained within increment "i" are the same.
The nonuniform resuspension of particle sizes is also considered by
measuring the mass loading as a function of particle size. The fraction
of the airborne mass contained within each size increment "i" is then
calculated and designated as f . The factors of f. and g^ are then
incorporated into the mass loading formulation as follows:
Air Concentration. = Air Mass Loading xf±x Soil Concentration xg± Eq. 2
234
-------
15
Summation over all the size increments results in the total air concentration:
Air Concentration^ Air Mass Loading x Soil Concentration
•• n ' • • - , ,
x £ f±g± ! Eq. 3
. . • i=l , . ., ,, ....,, ....
n " " ^ •--.-••.-•-
The term E f .g. weights the contribution of the plutonium from
1=1 1 x
each soil size fraction .to .the total resuspended material, thereby
-taking into account both the nonuniform resuspension of particles sizes
and .the nonhomogeneous distribution of. activity with particle size.
n
I f .g. is the "enrichment factor." . .'•,.
i=l
Data on the distribution of plutonium with soil particle size has
been obtained by the EPA (12) and by Tamura (13) for the vicinity
around Rocky Flats (Table 7.5). The ratio, g±, has been calculated for
each size increment and indicates an enrichment of activity to mass
associated with soil particles within the respirable size range. To
obtain, f.^, the data obtained by Chepil (16) for fields undergoing wind
erosion in Colorado and Kansas were used. The results of his findings
have been conveniently plotted by Slinn (17) and reproduced as Figure
7.5. Comparison of Chepil's data with another study substantiates the
applicability to the Rocky Flats situation. Chepil found 30% of the
airborne mass to be below 10 urn versus a study by Willeke (18) in an
area outside Denver where approximately 33% of the measured airborne
mass was below 10 ym. Values for f used in this analysis are included
in Table.7.5.
235
-------
to
CO
CD
IUU
m
D
m
Z
H
m
33
10 °
33
CD
O
33
Z
m
33
O
r-
m
v>
b
H
T~
20
-T r-1—I 1 1 T-
30 40 50 60 70 80
10 20 30 40 50 60 70 80 90 95 98 99 99.899.9
PERCENT OF MASS ASSOCIATED WITH PARTICLES OF LESS THAN EQUIVALENT DIAMETER
PARTICLE SIZE DISTRIBUTION OF RESUSPENDED SOIL
FIGURE 7.5
99.99
-------
17
Correction for Area Size
Use of the mass loading approach implies that the air concentration
is at equilibrium with the ground surface, i.e., a steady state situa-
tion exists in which the amount of material coming up from the surface
is balanced by the rate at which material is depositing back onto the
surface. In the strictest sense this limit can only be achieved for
source areas approaching infinite dimensions. For sources of finite
dimensions, a correction must be applied for area size.
Although techniques are presently under development to calculate
the air concentration arising from an area source, no generally accepted
method has yet" been identified. Usually, these approaches make use of a
standard diffusion equation, modified to handle area sources. One such
equation is the Sutton-Chamberlain diffusion equation:
= i- [exp(-
4VdDl
n/2
4 V
/if C0 n u
.
VTT C n u
Z
Eq.4
----•-'» -j
where x is the air concentration, Ci/m
Q is the amount of activity resuspending per unit area,
A £
per unit time, Ci/m sec.
V, is the particle deposition velocity, m/sec.
D and P_ are the distances from the receptor to the nearest
and furthermost edges respectively of the source area, meters,
u is average wind speed, m/sec.
23?
-------
18
C and n are Button parameters representing the; . , .
z
meteorological conditions. ••••.,
If the receptor is placed at the downwind edge or within the source
area, D- = 0 and Eq. 4 reduces to: , . .
X. . -
II -•»<-
4VdD2
n/2
)]
Eq.5.
Cz nu
For source areas approaching infinite depth, D_ -> <» and Eq. 5
becomes:
QA vd
Eq.6.
Comparing Equation 5 with Equation 6 shows that ' .
4V D n/2
[1- exp(- d 2 )] is the correction term to be applied for areas
/iF C n u
z
of finite size. . , ,
The area under consideration in this analysis has been described
2
earlier. It is bounded by Indiana Street and the 0.05 yCi/m isopleth
(Figure 7.3) with a width in the downwind direction of approximately 1
kilometer. This is the most highly contaminated off-site area and
includes sites of projected residential development. The meteorology
for the Rocky Flats area has been described (9) to have neutral stability
at least 50% of the time with a mean wind speed of 4.2 m/sec in 1975.
Healy (19) has suggested values for the parameters required in Equation
4: for the situation of neutral stability, Healy suggests C = .1 and n
; Z ' , ,.
= .25, while the ratio d/ , which depends upon the
238
-------
19
surface roughness, ranges ;between 0.003 and-0.008 for grassland, 0.005
will be assumed. Therefore, from Equation^ the correction factor for
the area under consideration is 0.66. , - .„ ,
Calculation of the Average Air Concentration Due to-Wind
Resuspens ion • . ...
The average soil concentration for the area is riot known, but it
2
would be somewhere between 0.05 yCi/m and the next higher isopleth of
2 '•" /•• • ' ' ':' " •' "•' •- ":"- .-"•• '-'•"•'• 2 ' ' ' '"" "' '
0.5 pCi/m . For calculational purposes, 0.25 yCi/m will be assumed or
approximately 10 DPM/g (based upon 20% of the radioactivity within the
first centimeter). By using the parameters developed in the previous
sections for the Rocky Flats area, one can estimate the average air
concentration due to wind resuspension: , ; •;. .,...-.•-,
Mass Loading x Soil Concentration x Enrichment Factor x Area Correction
Air Concentration
15
X10DPMX1.63X.66X10.
Ci
m
2.22xl012.DPM
= Air' Concentration
0.11. fCi
Air Concentration
m
The calculated value of 0.11 fCi/m agrees with the data obtained for
the sampling stations along Indiana Street, arid, as demonstrated earlier,
this concentration of airborne plutonium would produce exposures well
below EPA's guidance limits.
Inherent in the above calculation were some conservative assumptions.
', ">••' ,V - •*'. -^ . , '_ i ' ' f"" • ' -' * „ ^ -, tj, , „,, ' .;,, „„, .,,-,»-, ".,'.,-
> • •• " .-„ '^ - • -v» , , -i , ,i, ,. •-, i, ~ i - . ,f -, \jt - , .«•
-------
20
the contaminated area in the direction of the receptor. In reality, the
reported (9) wind rose for Rocky Flats indicates that the wind blows
from the westerly direction only about 50% of the time; the remaining
time it will be blowing from the direction of less contaminated land
and, therefore, less radioactivity would be available for resuspension.
Secondly, in deriving the area correction factor the effect of breathing
height was ignored with the ground level concentration being calculated.
This is a conservative assumption since the airborne concentration will
decrease as a function of the height above the ground. Although such
refinements could have been incorporated in the calculation, it was not
felt to be necessary because even these conservative assumptions resulted
in air concentrations well below the Agency's proposed guidance.
Resuspension of Soil by Mechanical Disturbances
The use of land contaminated with transuranium elements in the
vicinity of Rocky Flats for agricultural or building purposes can result
in localized resuspension and presents a potential inhalation hazard to
individuals in the immediate vicinity of the operation. In the vicinity
of Rocky Flats, there is some farming of wheat and the raising of corn
for livestock feed. Future development of the land for residential
purposes is also being advocated. Although only a limited amount of
experimental data is currently available as a basis for an assessment of
the inhalation hazard from such activities, some conclusions and recommendations
can be made.
In assessing the agricultural situation, data obtained by Milham
(20) have been used. In that study, a field contaminated
240
-------
21
with plutpn-ium. near the Savannah River Facility was subjected, to various
plowing and seeding activities associated with planting wheat. The
increase in the airborne activity above that from normal wind resuspen-
s ion was monitored at the location of the tractor operator and at the,
downwind edge of the field during , the various activities. An average
increase of a factor of 30 was observed ..in the level of resuspended
plutonium at the location of the tractor operator and an increase of a
factor of 5 at the edge of, the field. Based upon these observations,
the average air concentration .for the year can be calculated for these
two locations, assuming that the field is cultivated 30 days. of the year
for 8 hours per day. Again the area under consideration will be that
area of highest off-rsite contamination described earlier with an average
soil contamination level of 10 DPM/g. In the previous discussion of
wind, resuspension, this level of soil activity produced an air con-
Q
centratipn pf 0.11 fCi/m, . From Milham's data, this activity level
o
would increase to 3.0 fCi/m at the-location of, the .tractor operator and ,
to 0.55 fCi/m at the edge of the field during the agricultural operations.
The annual average, concentration at .each location is therefore: . :
1. Tractor Location, Average Annual Air Concentration
3.0 fCi/m3 x |T x —^ + 0.11 fCi/m3 x if x
330
360 ,
= 0.2 fCi/
24 360
3
24 360
+ 0.11 fCi/m x
m
2. Edge of Field, Average Annual Air Concentration
0.55 x
24
x
360
+ 0.11 x ~ x
• 24- 360,
+ 0.11 x
• 360
- 0.12 fCi/m
When these annual Pu-239 concentrations are compared to the value
3
of 2.6 fCi/m which was calculated by the PAID code to correspond with
241 -
-------
22
EPA's dose limits, one can conclude that agricultural operations in the
area of Rocky Flats would produce activity levels well within EPA's
guidelines. In addition, after the first plowing cycle, the surface
concentration should .be diluted by mixing with soil from below the
surface and subsequent plowings would produce air concentration lower
than that of the first year.
Regarding building activities, one can make projections based upon
the agricultural situation examined above. There does not appear to be
any reason why building activities, such as excavation and grading!
should produce higher instantaneous air concentrations than those
observed during agricultural plowing and, therefore, they should not
present a more restrictive situation. In addition, although the building
activity might take place for longer than the 30 days assumed in the
plowing situation, it must be kept in mind that the EPA guidelines are
based upon a chronic exposure for 70 years. Certainly, the bulldozer
operator would not be engaged in a building operation in an area of '
transuranium contamination for that number of years.
Resuspension of Dust Within the Home
The total amount of soil continuously in the home is not known but
2
an assumption of 10 g/m has been made (21). This amounts to about 3
2
Ibs of soil in a modest 1500 ft house. Because the floors are harder
and smoother than outside surfaces, the resuspension from them will be
higher. Resuspension factors of 10 m have been used in the past to
predict exposures in the work place and studies of PuO? deposited on
indoor surfaces have been consistent with a resuspension factor of 10
m'1 (22).
-------
23
The following exposure situation is postulated: the individual is
exposed to contaminated dust in the home for 24 hrs/day, 7 days/wk, for
70 years. The dust in the home has the same activity/gram as outside
. :.. . , . _ , , .. '••.••. • 2 '
soil and has an areal distribution within the home of 10 g/m . The air
concentration resulting from resuspended dust at 10 DPM/g would be:
10 DPM
x
Ci
10g 10~6
. - • -yr Wi v • "• —
2.22xl012 DPM m2 m
airborne dust concentration
3
0.045 fCi/m = airborne dust concentration
Again the level of airborne activity would result in dose rates
well within EPA's guidance limits. , ,
Resuspension of Dust from Contaminated Clothing -..-•,
Healy (19.)..-has. assumed that in a desert environment there will be 1
f\ r\
mg/cm (lOg/m) of dust on clothing. While it would certainly be, less
for nondesert .environments, this value will also be assumed for Rocky
Flats. Because of the proximity of the contamination to the nose and ,
the mouth, a resuspension factor higher than the normal outdoor resuspension
factor will be assumed. For this calculation, a value, of 10 m will
be assumed to be sufficiently conservative (10 m , is 3-4 orders of
magnitude higher, than values of wind resuspension factors observed at
Rocky Flats). Therefore, the resultant air concentration is:
10
10 DPM
~
Ci
2.22xl012 DPM
x
10
-6
_i
0.045 fCi/m"
m
243
-------
24
In addition to this air concentration being much lower than EPA's
guidelines, the period of exposure would not be continuous since the
clothing would be removed at least during sleeping. Therefore this
pathway would present no apparent hazard.
7.2.4 Conclusion
None of the inhalation pathways considered in the environs surrounding
the Rocky Flats Facility has resulted in doses close to the guidance
limits recommended by EPA for the transuranium elements. Even if the
conservative assumption is made that these exposures are occurring
simultaneously, the combination of pathways would amount to only a few
percent of the guidance limits. Even though every conceivable inhalation
pathway was not evaluated, it does not seem likely that one exists which
would have a combination of resultant air concentration and period of
exposure to produce significant doses compared to the guidance levels*
7.3 Ingestion Pathway
7.3.1 Plutonium and Americium in Drinking Water
Wastewater discharged from the Rocky Flats Plant as well as surface
runoff from the Plant site is collected in a number of holding ponds
where it is monitored for its radioactivity content before being discharged
into either Walnut or Woman Creek. Walnut Creek empties into the Great
Western Reservoir which provides part of the drinking water supply for
the City of Broomfield, while Woman Creek eventually empties into Standley
Lake which is a drinking water supply for the City of Westminster.
-------
.;: 25 ._ _ ' . '
The Rocky Flats water monitoring program consists of 1) effluent
monitoring of. the water being discharged from the holding ponds into
Walnut and Woman Creeks, 2) the monitoring of groundwater and 3) the
monitoring of the regional water supplies. In monitoring public water
supplies, samples are collected and analyzed from the drinking water
reservoirs (Great Western and Standley Lake) as well as the finished
water in several nearby communities. As with the air; monitoring, the
results of this sampling program are reported regularly to the responsible
Federal, State, and local government agencies and published on a yearly
basis. According to. the 1975 published data (9) the average concentrations
of plutonium and americium in finished water for the region were
< .027xlO~9 yCi/ml and < .032xlO~9 uCi/ml, respectively. The concentration
levels of plutonium and americium in the drinking water of the various
communities surrounding Rocky Flats are given in Table 7.6. Included in
this/ Table are results obtained by Poet and Martell (23) in 1970. . ..
Limited comparison of the two sets pf data shows little change in the
' " . I
activity levelsin £he drinking water during this five year period. As
with the airborne concentrations, these environmental levels-need to be
put into the perspective of EPA's guidance limits.
7.3.2 Bone Dose Resulting Due to Ingestion of Water
Assuming that the concentrations of Pu-239 and Am-241 in drinking
water are those reported for the city of Broomfield (the highest con-
centrations reported for the more immediate surrounding communities) and
that the consumption rate of water is 1.2 liters/day (ICRP Committee
-------
26
II) the annual water ingestion rates are:
Pu-239, Annual Ingestion Rate .
—9
0.04x10 ltd x 1200 ml x 365d = 18 pCi/yr
ml day yr
Am-241, Annual Ingestion Rate
0.029xlO~9 uCi x 1200 ml x 365d = 13 pCi/yr
ml day yr
Conversion of the above ingestion rates into dose rates can be
achieved through the use of Tables 7.7 and 7.8. The development of
these tables has been described in Annex III of EPA's guidance (1).
Table 7.8 has been normalized to an ingestion rate of 1000 pCi/yr of
various transuranium oxides and relates the years of ingestion to the
resulting dose rate. Plutonium and americium found in treated tap water
would probably be in a chemical form which is more soluble than the
oxide and which would have a higher GI tract transfer fraction (24).
For nonoxide forms, as shown in Table 7.7, the values listed in Table
7.8 should be increased by a factor of 10 for plutonium, while the
americium values remain the same. Based upon these conversion factors,
the bone dose rate after 70 years of ingestion of drinking water would
o
be 8.8x10" mrad/yr for Pu-239 and 6.2xlO~3 mrad/yr from Am-241. These
values are considerably below EPA's recommendation of 3 mrad/yr to bone
from the transuranium elements. •
7-3.3. Bone Dose Due to Ingestion of Foodstuffs
At present limited agricultural production is carried out in the
environs of Rocky Flats. Most of the food consumed locally is produced
246
-------
27
at considerable distances from :the Rocky Fiats Plant. Other than a few
family garden plots, the only crops grown locally are wheat and alfalfa.
A few cattle also are raised in the Plant's vicinity. Since future
residential development is projected for the Rocky Flats area, it would
be reasonable to project a concurrent increase in family gardening.
Therefore, an assessment has been carried out of the possible dose rates
associated with the consumption of foodstuffs which might.be. produced
locally. Because food sampling data are not presently available for the
Rocky Flats area, estimation of the potential doses,are based upon data
developed in other areas contaminated with transuranium elements and
from laboratory experiments of transuranium uptake by foodstuffs. ,
Conditions at Rocky Flats are not different enough to invalidate the use
of data developed in these other environments.
For purposes of this assessment, the ingestion rate of the transuranium
elements by people is considered to! be, .the product of the, rates at which
different contaminated materials are ingested and,the concentration of
the transuranium elements in each material. ,.
To put these calculations into perspective, the formulation of
Martin and Bloom (25) was adopted which relates the ingestion rate (Hi
for a particular nuclide to the average concentration of that miclide in
soil (C ) through the following formulation:
s
H
Eq. 7,
24?
-------
28
where I± is the ingestion rate of a particular item and DI is the discrimination
ratio between that substance and soil. This formulation makes for easy
translation of environmental levels into dose rates and, thereby, allows
direct comparison with EPA's guidance limits.
The soil concentration used in this assessment is the same as that
developed for the inhalation pathway calculations, i.e., 0.25 yCi/m2 for
Pu-239 and 0.045 pCi/m2 for Am-241 (18% of Pu-239 levels at the time of
maximum ingrowth). If this activity is evenly distributed throughout
the top 20 cm as a result of plowing, the average concentration, C , in
8
units of pCi/g would be:
0.25 uCi 10 pci
m
yCi
cm 1
X Ig x 20 cm
x —
m
104 cm2
=1.25 pCi/g Pu-239
and 0.22 pCi/g'(Am-241).
The materials considered by this analysis to be produced on this
land and consumed by individuals living in the area are leafy vegetables,
other food plants, cow milk, and beef. Also the casual and deliberate
ingestion of contaminated soil will be considered.
Leafy Vegetables and Other Food Plants
Plants grown in soil containing the transuranium elements can
become contaminated through uptake by the roots and systemic incorpora-
tion; in addition, the outer surfaces of the plant can have contaminated
soil deposited upon them as a result of resuspension. Numerous studies
have been conducted and several reviews (26, 27, 28) have been published
covering the range of discrimination factors that have been observed in
laboratory and field studies, generally the discrimination ratio for
-------
29
. -4 -6
incorporation of Pu-239 into the plant is between 10 to 10 on a
— T — 0
fresh weight basis and 10 to 10 for deposition on the plant surface.
The internal incorporation of americium-241 may be as much as 50 times
higher than that of plutonium, due to its greater solubility. Generally,
uptake factors for garden vegetables are at the upper end"of the range;
-4
therefore, for calculational purposes.a discrimination ratio of 10
will be assumed for internal deposition and 10 for external deposition
_3
when computing the intake of Pu-239, and corresponding ratios of 5x10'
and 10"1 for Am-24l. Since the calculations are for food in a table-
ready condition, decontamination of the food during processing must also
be recognized. In doing so, the assumption of Bloom and Martin (25)
will be used; namely, 90% of the contamination is washed off leafy-
vegetables and 99% of the contamination is removed from other food
plants during washing, peeling, etc. Likewise, the consumption rates of
foodstuffs obtained by Martin and Bloom from the USDA have been used
after conversion to a fresh weight basis (on the basis .that vegetation
is 70% water). Table 7.9 contains the resultant ingestion rates and
discrimination ratios used in this assessment.
Equation 7 was used to convert the ingestion rates and discrimination
factors of Table 7.9 into annual intakes of plutonium and americium. In
carrying out the food pathway calculations, the assumption was made that
25% of the entire intake for an individual arises from foodstuffs pro-
duced locally on land contaminated, with transuranium elements.
-------
30
The resultant ingestion doses are given in Table 7.10. In converting
the annual radionuclide intake to dose rates, Table 7.7 and 7.8 were
used with the following assumptions:
1. the duration of ingestion is 70 years
2. externally deposited material is in the oxide form
and 3. material biologically incorporated in plants and animals is
assumed to have a greater fraction transferred from the G.I.
tract to the blood. For plutonium, according to Table 7.7,
this results in an increase of a factor of 50 in the resulting
bone dose and a factor of 5 for americium.
Ingestion of Cow Milk
Martin and Bloom have developed a discrimination factor for dairy
—8
cows of 3.2x10 based upon assumptions of soil and vegetation consumption
by cattle. Using this value and again assuming that 25% of one's diet
is locally produced, one can calculate the ingestion rates of Pu-239 and
Am-241 as a result of milk consumption:
H (Pu-239) = C ID
s
= 1.25 £Ci 436e .25 x 365 dajs
day x . ~~~
1.6x10" pCi/yr
H (Pu-239)
H (Am-241) = .18 H (Pu-239)
H (Am-241)
yr
~9in
3'2xl°
-8
28xlO~3 pCi/yr
Since these transuranium elements would be biologically incorporated,
the dose rates of Table 7.8 would be increased by a
-------
31
factor of 50 for Pu-239 and a factor of 5 for Am- 241. The resultant
bone doses attributable to the consumption of milk are given in Table
7.9.
Ingest ion of Beef
Similarly., Martin and Bloom developed discrimination factors for
beef muscle and beef liyer and these have been utilized in our calculations
of ingestion rates:
Beef Muscle
H (Pu-239) = C ID
S
,':..,•-... v ::..'•' •"
H (Pu-239) - 1.25 pCi
,\ . . '.. 8
.
•day-.
.25 x 365d
• .-. ; yr -•
3.3xlo
-
-5
H (Pu-239) = 1.02 pCi/yr
H (Am-241) = .18 H (Pu-239)
H (Am-241)
Beef Liver
H (Pu-239)
l.SSxlO"1 pCi/yr
1.25 £Ci 13g .25 365 day 2.xlp
jC •• 3t 3t * -,' i • «
g day yr
-3
H (Pu-239) - 2.96 pCi/yr
H (Am-241) = .18 H (Pu-239)
H (Am-241) = 5.33X10"1 pCi/yr
Assuming that transuranium material is biologically incorporated, the
resultant bone dose rates after 70 years of ingestion have been calculated
and are included in Table 7.10.
-------
32
7.3.4 Bone Dose Due to Soil Ingestion
Casual Ingestion
Bloom and Martin (25) have assumed a casual ingestion rate for a
desert environment to be approximately 3-4 g/year. Likewise, Rogers
(21) has estimated the accidental ingestion rate of soil as a result of
hand to mouth transfer to be 3-4 g/yr. Based upon these estimates, one
can calculate the plutonium and americium ingestion and resulting dose
rates. The ingestion period is assumed to be 70 years and the surface
soil concentration of Pu-239 is that developed previously for unplowed,
undiluted soil in the vicinity of Indiana Street; i.e., 10 DPM/g (4.5
pCi/g). The americium concentration, also as before, is assumed to be
at its maximum contribution of 18% or 0.8 pCi/g. The resulting bone
dose have been calculated assuming the transuranic material is in the
oxide form and these have been included in Table 7.10.
Deliberate Ingestion
Healy (29) has addressed the problem of deliberate soil ingestion
by children below the age of five. After reviewing the limited available
data on the topic, he concluded that a deliberate soil ingestion rate of
20 g/day would be a reasonably severe case. Applying this estimate to
the Rocky Flats situation would produce the following ingestion rates
for deliberate soil ingestion:
H (Pu-239)
C ID*
s
4.5 pCi/g x x
day
365 da^s
yr
H (Pu-239) = 3.24xl04 pCi/yr
* D is equal to 1.0
-------
r-r: 33
H (Am-241):- .18 (Pu-239)
H (Am-241) = 5.84xl03 pCi/yr
Since this condition of excessive soil ingestion would occur over a
relatively few years, the resultant dose rates were calculated assuming
the period of ingestion to be 5 years and are included in Table 7.10.
7.3.5 Conclusions
From the results presented in Table 7.10, one can conclude that,
even for the unlikely case where the calculated doses for all pathways
are additive, the doses received by ingestion would be well below the
EPA guideline of 3 mrad/yr to bone. In reality, an individual in the
vicinity of Rocky Flats would receive much lower doses than those
calculated. It is deemed very unlikely that one could identify other
possible ingestion pathways of such magnitude that they would result in
bone doses exceeding 3 mrads in any year.
-------
Table 7.1
SURFACE AIR PU-239 CONCENTRATION AT ROCKY PLATS
ATTOCURIES/CUBIC METER
JAN.
FEB.
MAR.
APR.
MAY
JUNE
JULY
AUG.
SITE
SEP.
OCT.
NOV.
DEC.
1970 — *- — __ __ 1990.00 1250.00 790.00
1971 1960.00 — 7140.00 9730.00 4920.00 3800.00 2980.00 3530.00
1972 5430.00 1670.00 4610.00 1460.00 2080.00 6610.00 4720.00 1380.00
1973 1160.00 3640.00 2520.00 612.00 1780.00 3040.00 2920.00 3320.00
1974 402.00 802.00 891.00 1810.00 3060.00 5470.00 2670.00 3330.00
1975 1260.00 1360.00 1780.00 2180.00 2190.00 1160.00 567.00 426.00
19.76 680.00 1240.00 864.00 — —
850.00 693.00 2260.00 962.00
4040.00 5770.00 5770.00 3160.00
1620.00 498.00 1860.00
1050.00 2010.00 1810.00 1690.00
1120.00 407.00 580.00- 643.00
179.00 — 1220.00 655.00
SITE 02 •,
ro
IF*
SITE #3
SITE #4 "
V
1972
1973
1974
1975
1976
1972
1973
1974
1974
1975
1976
FA n A T A
37.80
16.80
141.00
12.20
«•»
18.40
21.70
—
288.00
184 .-00
—
57.7.0
23.20
34.70
23.10
41.70a
39.10
— ..
399.00
303.00
—
55.80
462.00C
56.80
14.40
24.20
163. 00C
1850.00
72.60
—
716. 00C
135.00
39.70
—
24.00
283. 00C
--.•-'
254.00
236.00
—
51.80
176.00
—
—
40.40
—
1460.00;
139.00
109.00
98
57.70 92
140.00 78
™* 27
— — HH
""*** ~* ~
42.00 25
— —
-758.00 1430
684.00 118
319.00 98
.90
.10
.70
.40
.80
.00
.00
.20
55.50
65.00
58.10
14.00
— "-
25.70
__
222.00
146.00
63.10
119.00 609.00 , 48.50
152.00 31.50 25.20
34.20 24.00 29.20
9.98 — 10.60
21.90 18.50
38.20 21.50 11.00
199.00 395.00 1240.00
72.20 189.00 188.00
—
45.20
76.30
43.70
16.40
25.60
16.90
710.00
128.00
Errors are less than 20% except:
a -error between 20% and 100%
b -error greater than 100%
c -suspect, omitted from average
* Table from reference 2.
-------
; Table.7.2
Plutonium in Three-to Six-Kilometer-(2-to 4-Miles-)Distant Ambient Air
Number of -
Station Samples Taken
S-31
S-32
S-33
S-34
S-35
S-36
S-37
S-38
S-39
S-40
S-41 -,.-'-
S-42
S-43
S-44
Summary
12
12
12
3
3
2
12
10
12
12
12
12 ;
11
'12
137
Less Than
Detectable
1
' "•• V '• 1
1
1
0
0
0
0
1
0
, . . 1
: i .,;
• - ••• i' .• ',
. ' .- i- - -;
•=• - g ~
Volume
(cubic meters)
461,547.0
543,346.0
531,886.0
118,243.0
119,322.0
57,286.0
525,181.0
460,089.0
5,02,129.0
486,876.0
472,698.0
416,244.0
360,818.0
429,709.0
5,485,374.0
Concentration (xlO~ yCi/ml)
C C a
maximum
0.144
0.134
0.097
0.176
0.116
0.012
0.198
0.097
0.102,.
0.198
0.136
0.137
0.185
0.094
0.198
average
<0.032 ± 96%
<0.035 ± 96%
<0.034 ± 95%
<0.037 ± 550%
0.027 ± 538%
0.012 ± 1734%
0.056 ± 93%
0.027 ± 108%
<0.026 ± 97%
0.054 ± 92%
<0.033 ± 99%
<0.037 ± 96%
<0.056 ± 105% t
<0.029 ± 103%
—
Volume-Weighted Average
a. Volume-weighted average.
* Table from reference 9".
<0.037 ± 29%
w
-------
37
Table 7.3
Annual Dose Rate to Various Lung Compartments from
Chronic Exposure to Plutonium and Americium Aerosols
(Concentration » 1 fCi/m and Particle AMAD - 0.05, 1.0, and 5.0 micrometers)
Plutonium-239
Duration of
Exposure
years
1
5
10
70
Duration of
Exposure
years
70
Pulmonary
mrad/yr x 10
O.OSv l.Ov 5. On
Tracheo bronchial
mrad/yr. x 10
0.05p l.Ov 5. On
3.9 1.5 .7 2.7 1.1 6.1
9.1 3.5 1.7 3.7 1.5 7.9
9.8 3.8 1.8 3.8 1.6 8.1
9.9 3.8 1.8 3.8 1.6 8.1
Americium-241
Pulmonary -
mrad/yr x 10
6.5v l.Ov 5.0v
10. 4;2 1.9
Nasopharyngeal
mrad/yr x 10~
0.05u l.Ou 5.0u
.04 11. 30.
.04 11. 30.
.04 11. 30.
.04 11. 30.
256
-------
38
Table 7.4 ..-...,
Annual Dose Rates to Various Organs from Chronic
Exposure to Plutonium-239 and Americium-241
Aerosols AMAD=ly; Concentration 1 fCi/m3
Duraction of
Exposure
(years) Liver
1.
5
10
15
20
30
40
50
70
.001
.018
.052
.089
.13
.19
.24
.29
.36
Pu-239
(mr ad /year)
Bone T-B Lymph
Nodes
.0005
.0065
.019
.034
.049
.078
.11
.13
.17
.40
4.0
7.0
8.7
9.8
12
14
15
19
Am-241
(millirad/year)
Liver Bone
.0015
.019
.055
.095
.13
.20
.26
.30
.37
.0005
.007
.021
.036
.052
.082
.11
.14
•18
T-B Lymph
Nodes
.39
4.2
7.4
9.1
10
12
14
16 '
20
257,
-------
Table 7.5
ro
Sample
RF 1A
RF IB
RF 1C
RF 2A
Tamura
Size Increment (ym)
2000-105
105-10
<10
2000-105
105-10
<10
2000-105
105-10
<10
2000-105
105-10
2000-105*
105-10
<10
Wgt. Fract.
.62
.18
.20
.63
.17
.20
.64
.16
.20
.46
.34
.20
.47
.42
.11
Act. Fract.
.07
.40
.53
.39
.06
.55
.43
.07
.49
.13
.37
.50
.11
.61
.28
gi
.12
2.21
2.65
.63
.34
2.74
.68
.46
2.47
.28
1.10
2.48
.23
1.45
2.54
£ i i
i i
.7
.3 2.34
_,
.7
.3 1.06
_
.7
.3 1.06
•v '•'
w
.3 1.51 «>
av. 1.49
_
.7
.3 1.78
*Data only for untreated samples and normalized to particle sizes less than 2000 ym.
Overall Average 1.63
-------
40
Table 7.6*
Plutonium and Americium in Public Water Supplies
Reservoirs
Number of
Samples Taken
Great Western
Great Western3
Standley Lake
Summary
Finished Water
Arvada
Boulder
Broomfield
a
Broomfield
Denver
Golden
Lafayette
Louisville
Thornton
Westminster
Summary
Average
Reservoirs
Great Western
Standley Lake
Summary
Finished Water
Arvada
Boulder
Broomfield
Denver
Golden
Lafayette
Louisville
Thornton
Westminster
Summary
Average
36 /
36
72
11
12
39
11
11
12
11 ;
12
36
155 .
Number of
Samples Taken
38 .
37
75
11
11
37
11
11
12 .;
12
12
39
156
Plutonium
c
minimum
<0.013
.046 -«
<0.013
<0.013
<0.005 "
<0.005
<0.013
<0.005
<0.005
<0.005
<0.005
<0.005
<0.013
,<0.005
-
Americium
c
minimum
0.014
<0.013
<0.013
,<0.001 ,..
<0.001
<0.023
<0.001
<0.001
<0.001
<0.001
<0.001
<0.013
<0.001
Goncentration (x
c
maximum
0.952
': .214 !
0.142
0.952
o:.6i9
0.014
0.133
.038
0.016
0.048
0.030
0.012
0.018
0.210
1 ; 0^210:
" —
10 • yd/ml)
C b
average
<0,.099 ± 58%
<0.036 ± 23%
—
<0.006 ± 50%
<0.007 ± 17%
<0.041 ± 26%
<0.008 ± 29%
<0.009 ±107%
<0.007 ± 67%
<0.006 ± 21%
<0.009 ± 32%
<0.041 ± 31%
-
<0.027 i 49%
—9
Concentration (x 10 yCi/ml)
c
maximum
<0.090
<0.090
<0.090
'.- "" - ." . - -*'"- - ;- >
.„..-. 0.239
-.' 0.015
0.150
0.420
0.044
0.030
0.400
0.007
0.079
0.420
C b
average
<0.033 ± 20%
<0.027 ± 19%
—
<0.026 ± 180%
<0.006 ± 180%
<0.029 ± 31%
<0.043 ± 196%
<0.009 + 80%
<0.007 ± 67%
<0.039 ± 185%
<0.005 ±3%
<0.029 ± 18%
-
<0.032 ± 25%
* Table from reference 9 .
a. Data of Poet and Martell (1970);
b. Sample-weighted average
-------
41
Table 7.7
Fraction of Ingestion Material Transferred to
Blood from the Gastrointestinal Tract
Radionuclide
Plutonium-238
Plutonium-239
Plutonium-240
Plutonium-241
Americium-241
Curium-244
Transfer Fraction
non-oxide oxide
10
-3
10
-3
10
-3
10
-3
10
-3
10
-3
10
-3
10
,r4
10
-4
10
-3
10
-3
10
-3
Biologically
Incorporated
5x10
-3
5x10
-3
5x10
-3
5x10
—3
5x10
,-3
5x10
-3
.26P
u
-------
42
Table 7.8
Annual Dose Rate Due to Chronic Ingestion of
Plutonium-239 Oxide, Americium-241, Plutonium-241 and Curium-224
Annual Intake 1000 pCi/Year
Duration of Plutonium-239 Oxide
Inges'tion (yrad/year)
Years Pone Liver Whole
Body
1
5
10
15
20
30
40
50
70
0.9
4.3
8.4
1.2X101
1
1.6x10
i
2.4xlOx
1
3.0x10
i
3.7x10
i
4.8X1Q-1
2.4
1.2X101
2.2X101
3.2X101
: I
4.1X10-1
i
s.exio-1
,1
6.9x10
1
S.lxKT
i
9.8x10
_•}
4.6x10 J
2.7xlO~2
4.5xlO~2
6.6xlO~2
»
8.6x10
•i
1.3x10 •
_i
1.6x10,
_1
1.9x10 •"•
_i
2.6x10
Americium-241
(yrad/year) .
Bone Liver Whole
Body
9.2
4.5X101
S.SxlO1
1.3xl62
2
1.7x10
0
2.4x10
2
3.1x10
2
3.8x10 '
0
4.9xlOz
1
2.5x10
1.2xl02
2.3xl02
3.4xl02
2
4.3x10
"}
5.9x10^
2
7.2x10
2
8.3x10^
2
9.9x10
_2
4.9x10
2.4X10"1
4.7X10'1
6.9X10"1
i
9.0x10
1.3
1.7
2.0
2.6
-------
43
Table 7.9
Food Ingestion Rates and Radionuclide Discrimination Ratios
Substance
Leafy Vegetables
Other Vegetables
Cow Milk
Beef Muscle
Beef Liver
Soil (casual)
Soil (deliberate)
Ingestion Rate(g/day)
270
740C
436
273
13
.01
20
Pu
Am
Pu
Am
Pu
Discrimination Ratio
Pu(ext.) [10
Pu(int.) 10"
Am(ext.)
Am(int.)
Pu(ext.)
Pu(int.)
Am(ext.)
Am(int.) ;5xlO~
5x10"
10
3.17x10"
3.17x10"
3.29x10"
3.29xlO
2.0xlO
~3
Am
Pu
Am
Pu
Am
2.0x10
1.0
1.0
1.0
1.0
a. from ref. 25.
b. assumes vegetation is 70% water
c. assumes retention and transport within cow is the same for Pu and Am
262
-------
Ingestion
Substance , Radionuclide
Brisking Water Pu
Am •.. •
Leafy Vegetables Pu (ext.)
Py (int.,)
Am; (ext.)
'•,.." Am (int.)
Other Vegetables Pu,,(ext.)
Pu (int.)
Am (ext.)
Am (int.)
Cow Milk Pu
Am
Beef Muscle Pu
Am
Beef Liver Pu
Am '' "
Soil (casual) Pu "
Am
(deliberate) Pu
" , : ." '• ,. /Am ••-••••
" 44
Table 7.10
and Resultant Bone Dose Rates
,,:•-_-•:
• - " • • • •' •;.
Ingestion Rates (p Ci/yr)
18
13
297
3
53
27
82
9
15
74
1.6xlO~3
.28xlO~3
1.02
l.SSxlO"1
2.96
5.33X10"1 ..-:.
18.0
3.2 ' , . ..
3.24xl04
'.'- 5.84xl03
Total
2 £3
70tlfl Year Bone
Dose Rate ,
(inrad/yr)
8.8xlO~3
6.2X10"73
.014
.071
.026
.067
.004
.020..
.007
,018
.40xlO~5
.67xlO~6
2.5xlO"3
.2.8xlO~4
7.1xlO~3
1. 28xlO~ 3
8.6xlO~4
1.6xlO~3
.44
'"'.;; 26"
0.653
-------
45
Reference
1. Proposed Guidance on Dose Limits for Persons Exposed to Trans-
uranium Elements in the General Environment, USEPA, Washington,
B.C. (September 1977).
2. H. Volchok, M. Schonberg, and L. Toonkel, Pu-239 Concentration in
Air Near Rocky Flats. Colorado, HASL-315, Health and Safety Laboratory,
USERDA (1977).
3. P. W. Krey and E. P. Hardy, Plutonium in Soil Around the Rocky Flats
Plant, HASL-235, Health and Safety Laboratory, USERDA (1970).
4. Task Group on Lung Dynamics, Health Physics, 12, p!73 (1966).
5. H. Volchok, R. Knuth, and M. Kleinman, "The Respirable Fraction of
Plutonium at Rocky Flats," Health Physics, 23, p395 (1972).
6. G. A. Sehmel, Airborne 238Pu and 239Pu Associated with the Larger
than Respirable Resuspended Particles at Rocky Flats During July 1973,
BNWL-2119, Battelle Pacific Northwest Laboratories (1976).
7. R.E. Sullivan, Plutonium Air Inhalation Dose (PAID), ORP/CSD-77-4,
USEPA (1977).
8. P. Krey et al., Plutonium and Americium Contamination in Rocky
Flats Soil. 1973. HASL-304, Health and Safety Laboratory, USERDA
(1976).
9. Environmental Monitoring at Major USERDA Contractor Sites - Cy
1975, ERDA-76-104, Vol. 1, USERDA, Washington, D.C. (1976).
10. L. R. Anspaugh, L. H. Shinn, P. L. Phelps, and N. C. Kennedy,
"Resuspension and Redistribution of Plutonium in Soils," Health
Physics. .29_, p571 (1975).
11. L. R. Anspaugh, !'The Use of NTS Data and Experience to Predict Air
Concentrations of Plutonium Due to Resuspension on the Enewetak
Atoll," The Dynamics of Plutonium in Desert Environment, NVO-142,
p299 (1974).
12. D. E. Bernhardt, "Resuspension of Plutonium; It's Particle Size
Distribution in Soil," in Evaluation of Sampling and Collection
Techniques for Environmental Plutonium, ORP/LV765, USEPA (1976).
13. T. Tamura, "Effect of Pretreatment on Size Distribution of Plutonium
in Surface Soil from Rocy Flats, in Transuranics in Desert Ecosystems,
NVO-181, p. 173 (1977).
14. T. Tamura, "Physical and Chemical Characteristics of Plutonium in
Existing Contaminated Soils and Sediments," in Proceedings of the
International Symposium on Transuranium Nuclides in the Environment
(NOV. 1975), IAEA, Vienna.
-------
46
15. C. J. Johnson, R. R. Tidball and R. C. Severson, "Plutonium Hazard
in Respirable Dust on the Surface of Soil," Science, 193, p488
(1976). : ~.
16. W. S. Chepil, "Sedimentary Chacteristics of Dust Storms: III
Composition of Suspended Dust," Am. J. Sci., 225, p206 (1957).
17. W. G. Slinn, "Dry Deposition and Resuspension of Aerosol: Particles -
A New Look at Some Old Problems," in Atmospheric-Surface Exchange
of Particulate and Gaseous Pollutants, CONF 740-921, ERDA, Washington,
D.C. (1974).
18. K. Willeke, K. Whitby, W. Clark, and V. Mayle," Size Distribution
of Denver Aerosols - A Comparison of Two Sites," Atm. Env.9 j^, p609
(1974). '
19. J. W. Healy, A Proposed Interim Standard for Plutonium in Soil, LA
5483-MS, Los Alamos Scientific Laboratory (1974)..
20. R. C. Milham, J. F. Schubert, J. R. Watts, A. L, Boni, and J. C.
> Corey, "Measured Plutonium Resuspension and Resulting Dose from
Agricultural Operations on an Old Field at the Savannah River, Plant
in the Southeastern U.S.," in Proceedings of the International'
Symposium on Transuranium Nuclides in the Environment, (Nov. 1975),
IAEA, Vienna.,
21. D. R. Rogers, Mound Laboratory Environmental Plutonium Study 1974,
MLM-2249, Mound Laboratory. (1975). -
22. J. S. Jones and S. F. Pond, "Some Experiments to Determine the
Resuspension Factor of Plutonium from Various Surfaces," Surface
Contamination, B. R. Fish (ed.), Pergamon Press, New York, N.Y;
(1964), p83.
23. S. E. Poet and E. A. Martell, "Plutonium-239 and Americium-241
Contamination in the Denver Area," Health Physics, - 23, p537 (1972).
24. R. P. Larsen and R. D. Oldham, "Plutonium in Drinking Water: Effects
of Chlorination on its Maximum Permissable Concentration," Sci.,
201, p. 1008 (1978).
25. W. E. Martin and S. G. Bloom, "Plutonium Transport and Dose Estimation
Model," in Proceedings of the International Symposium on Transuranium
Nuclides in the Environment, (Nov.r 1975), IAEA, Vienna. . .., .
26. D. E. Bernhardt, and G. G. Eadie, .Parameters for Estimating the
Uptake of Transuranic Elements by Terrestrial Plants, ORP/LV-76-2,
USEPA (1976) , •.-.-.-...
27. R. L. Thomas and J. W. Healy, An Appraisal of Available Informa-
tion on Uptake by Plants of Transplutonium Elements and Neptunium,
LA-6460-MS, Los Alamos Scientific Laboratory (1976).'
-------
28. R. A. Bulman, Concentration of Actinides in the Food Chain, NEPB-
R44, Harwell (1976).
29. J. ¥. Healy, An Examination of the Pathways from Soil to Man for
Plutonium, LA-6741-MS, Los Alamos Scientific Laboratory (1977).
266
-------
8. DISCUSSION OF COMMENTS SUBMITTED BY CARL JOHNSON, M.D.,
DIRECTOR OF HEALTH, JEFFERSON COUNTY, COLORADO
8.1 Introduction •
Dr. Carl Johnson has, during the last several years, proposed and
strongly advocated use of a soil sampling and analysis procedure which
supposedly gives a better indication of the inhalation hazard to
persons in the vicinity of environmental transuranium element
contamination then other commonly used methods.
The method proposed by Dr. Johnson requires collection of the
loose surface soils with a broom and dustpan, followed by a size
separation procedure, and retention of only that fraction of all
particles with mass less than that equivalent to a 5 micrometer sphere
of Pu02. Results are reported in terms of activity per gram of the
material analyzed.
Dr. Johnson has also published and widely diseminated certain
other conclusions related to the health risk as derived from these
measurements. A copy of a paper prepared by Dr. Johnson, which
summarizes most of his pertinent views, is appended. The staff of the
Office of Radiation Programs has reviewed these submittals and its
conclusions are presented in this section.
8.2 Applicability of Soil Sampling Methods
The usefulness of any soil sampling method to indicate the
potential inhalation hazard to individuals is questionable because the
correlation of air and soil concentration must be made by
calculational models which require certain specific information
applicable to the particular site. The limited accuracy, precision,
and reproduciblity of environmental measurements necessarily
introduces some uncertainty into such calculations. The relationship
of a soil concentration per unit area to an air concentration per unit
volume is generally given by a resuspension factor, defined as
RF = air concentration/m-*
soil concentration/m^
Observed values of the resuspension factor for environmental
contamination existing for more than a few years are generally between
10~9 and lO"11^. However, before a resuspension factor can be
applied to a site, it must be derived from a statistically significant
number of measurements, for that specific site. This may be difficult
because soil concentrations can vary greatly from sampling location to
sampling locations, and only a fraction of the particulate content of
the air is derived from the soils in the immediate vicinity of the
sampling location.
267
-------
More general methods based on the mass loading of suspended
particulates in air, usually derived on a regional basis, have also
been suggested and appear to give a much better indication of the time
averaged air concentration at a specific location. However, in all
cases it must be recognized that soil concentration measurements are a
secondary method for estimating airborne particulate concentrations
and their success is directly related to the amount and quality of
data available to make the proper conversion.
Despite the difficulties noted above, Dr. Johnson has chosen to
use soil concentration data as the primary index for evaluating
potential inhalation exposures. Therefore, the questions which must
be addressed are whether the proposed sampling and analysis technique
has general validity, how it compares to other methods, what the
significance of the differences represents in terms of public health
protection, and whether Dr. Johnson uses his data correctly in
determining the inhalation hazard to individuals. These points will
be considered in turn.
8.3 Inhalation Hazard
The inhalation hazard of airborne particulates is directly
related to the concentration of particles in the air near ground
level. The mechanism of transport to the different compartments of
the respiratory system, deposition, and retention has been extensively
studied. The Task Group on Lung Dynamics of the International
Commission on Radiological Protection published a report (J. Health
Physics, Vol.12, pp. 173-207, 1966) which specifically considered lung
deposition and retention in terms of an activity median aerodynamic
diameter (AMAD) of particles as a basis for lung dosimetry. These
models require knowledge of the amount of radioactivity associated
with all sizes of airborne particles, and not of only a selected
fraction. Both the concentration and particle size distribution in
air are best determined by air sampling devices specifically designed
for that purpose. These data then provide the input for calculation
of the inhalation dose rate to persons and evaluation of the potential
inhalation hazard.
The sampling and analysis method proposed by Dr. Johnson does not
accurately measure the entire spectrum of particle sizes as actually
found in the environment by including only a portion of all particles
in the reported results. Therefore, the distribution as derived by
Dr. Johnson's method does not provide all the data required as input
by the mathematical models for dose calculation to the lung. The
results from the method proposed by Dr. Johnson therefore cannot be
used for the evaluation of an inhalation hazard by the standard
methods.
:08
-------
8.4 Effect of Analysis-Procedure onParticle Size Distribution
The chemical analysis procedure proposed by Dr. Johnson is
designed to alter the size distribution of the samples collected in
the environment. It achieves this result by subjecting the soil
particles to various chemical and physical dispersion methods which
break down the bonding forces which hold the microaggregates
together. The peroxide treatment removes the'organic matter which
serves as a binding component, and the ultrasonic treatment separates
and disperses the particles. As a result, the distribution after
treatment tends to have many more particles in the smaller size range.
and therefore to indicate a larger fraction of the total plutonium to
be associated with particles in the "respirable size" range.
The effect of the treatment used by Dr. Johnson differs with the
type of soil. For the soils in the vicinity of the Rocky Flats Plant,
it has been shown (Tamura in Transuranics in Desert Ecosystems, Report
of the Nevada -Applied Ecology Group, U.S. Dept. of Energy, NVO-181,
Nov. 1977) that the dispersive treatment reduced the particle size
from an initial distribution where less than ,60% of the activity was
associated with the "respirable range" of-particles to a point where
more than 90%; of the.activity was in that range. The activity median
aerodynamic diameter was changed,from 43 um for the untreated soil to
1.6 um for the hydrogen peroxide treated - ultrasonically dispersed
soil.
'It must be concluded that the analysis method used by Dr. Johnson
drastically alters the size distribution of the soil samples and does
not accurately reflect the fraction of radioactivity associated with ,
soil particles in the "respi_rable size" range.
8.5 Particle Sizes and Inhalation • "•--.
The method proposed by Dr. Johnson involves measurement of
particle size by a standard water-sedimentation technique commonly
used by soil scientists. The diameter determined by this technique is
referred to as the Stokes diameter, and is derived from the settling
velocity and density., However, it is the aerodynamic diameter (Da)
rather than the Stokes diameter (Ds) which is generally used in
models which have been developed to describe the deposition and
retention of inhaled particles in the evaluation of an inhalation
hazard. This aerodynamic diameter-, defined as the diameter of a unit
density sphere having the same terminal velocity as the particle lii
question,, takes into account the variable linear dimensions, density,
and aerodynamic drag factors which may vary considerably from particle
to particle. The Task Group on Lung Dynamics of the International
Commission on Radiological Protection has recommended use of the
aerodynamic diameter in assessing inhalation hazards.
oro
-------
For the same terminal velocity of a particle, the Stokes diameter
and the aerodynamic diameter can be related by •
/PDS = Da
that is, the aerodynamic diameter is larger than the Stokes diameter
by a factor equivalent to the square root of the density. For PuC>2
particle with a density of 11.4g/cm3, this factor is 3.4.
Therefore, the 5 um particle as measured by water sedimentation
referred to by Dr. Johnson actually is a particle with a 16.9 um
aerodynamic diameter. Because particles with aerodynamic diameters
exceeding 10 um are completely removed from the incoming air as it
passes through the nose, and do not penetrate to the lung, the
proposed method may greatly overestimate the respirable component of
soils.
8.6 Comparison of Results Obtained by Different Methods
Significant differences exist in results of measurements of soil
concentration for the same area when reported by Dr. Johnson as
compared to results obtained by other methods, and it is important to
recognize the reason for these differences. It is reasonably well
established that most environmental contamination by transurium
elements, whether derived from fallout or more localized sources, is
associated primarily with the smaller soil particles near the
surface. Therefore, all methods - including the method proposed by
Dr. Johnson - will give approximately the same results when these are
reported in terms of activity per unit area. Significant differences
are, however, introduced when the results are reported in terms of
activity per unit weight or mass because the basis for comparison then
is a function of the specific sampling procedure. Methods which
collect a greater amount of soil per unit of surface area, such as
those which include all material to a given depth, then will give a
smaller activity per unit weight (e.g. curies per gram) than those
which limit the amount of soil included in the analysis by either
sampling to a smaller depth or by eliminating a portion of the entire
sample by size fractionation. Because of the much higher activity to
mass ratio in the size fraction sampled by Dr. Johnson, that method
will generally give higher numerical results. It is important that
the reasons for1 these differences be understood and should be noted
that these differences do not represent real differences in the
environment. It is very important, therefore, that the exact method
used be specified and to recognize that the results obtained by
different methods cannot be used interchangably.
270
-------
8.7 Dust Inhalation and Lung Dose • --
A large portion of Dr. Johnson's discussion is directed toward
the probability of inhaling a plutonium particle. The issue, however,
is what is the dose/effect of that particle when it is inhaled — -.
regardless of the probability of inhaling it. ,
Dr. Johnson erroneously assumes that a resuspended 5 um particle
will consist solely of PuC>2 and proceeds to calculate the mass and
activity of this particle based upon the specific activity and density
of Pu02* Dr. Johnson's assumption will considerably overestimate
the activity associated with a particle of a given size, because most ,
resuspended particles consist of a large soil particle with a smaller
plutonium particle associated with it. Hayden (in "Atmosphere -
Surface Exchange of Particulate and Gaseous Pollutants", ERDA
CONF-740921, 1974) measured the sizes of plutonium particles
associated with soil particles at Rocky Flats and found the Pu(>2
particles to have a median diameter of approximately 0.08 um. This is
consistent with a report by Little and Whicker (Journal of Health
Physics, Vol. 34, pp. 451-7, May 1978) which states that the
contaminated oil at Rocky Flats was reportedly drained through 2-3 um
filters before placement into barrels.
Dr. Johnson greatly overestimates the amount of soil inhaled,
when he states that an individual may inhale and retain as much as 10
to 12 grams of dust in the lung over the course of a few months.
Airborne particulate mass loadings at rural sites, as reported by the
National Air Surveillance Network average on an annual basis between ,
10 to 50 ug/m3. The amount of dust inhaled by an individual can be
calculated from this mass loading. For an assumed.dust leading of
50 ug/m3 (the average for Colorado is much lower) and a.breathing
rate of 20 m3/day, less than 0.4 g/yr would be inhaled by a person
living near Rocky Flats.
Krey (CONF-740921, ibid) has measured the activity per gram of
respirable dust in the vicinity of Rocky Flats and found the
concentration to be approximately 5 dpm/g. Based upon a 0.4 g/yr
inhalation rate, an individual would therefore inhale 2 dpm each year
or 0.9 pCi/yr. It can be shown that continuous inhalation of
19 pCi/yr inhaled continuously for 70 years is equivalent to a
pulmonary dose rate of 1 mrad/yr (Proposed Guidance on Dose Limits for
Persons Exposed to Transuranium Elements in the General Environment,
EPA-520/4-77-016). Therefore, the maximum dose rate to .an individual
in the area of the Rocky Flats Plant as calculated by this method
would be only about 0.05 uCi/year. This calculated dose rate is lower
than the Guidance recommendation limit of 1.0 millirad per year by
approximately a factor of twenty .
271
-------
8.8 "Distribution" Factor
The Environmental Protection Agency has recognized deficiencies
in how most sampling methods are used to evaluate the contribution of
the smaller particles in the soil to the inhalation hazard, and has
developed a method which considers the ratio of activity to mass in
different particle size ranges (termed "enrichment" or "distribution"
factor). It is intended to both minimize the number of analyses
required and provide a maximum of useful information. The method
requires a detailed analysis of a small number of representative soil
samples from a given location, the results of which can then.be
applied to all samples taken from that area. Most analyses can then
be performed on soil samples including all size fractions (generally
all particles smaller than 2 millimeters - the definition of agronomic
soil) while site-specific information can be derived on the
composition of the resuspended portion. The method is intended to be
used with the mass loading calculational procedure for deriving the
corresponding air concentration, rather than with the resuspension
method which already includes the correction term in the experimental
data. In effect, the "enrichment" or "distribution" factor converts
the average radioactivity to mass radio for the entire soil sample to
the radioactivity to mass ratio of only the resuspended fraction.
Details of the method are described in EPA document 520/4-77-016
entitled "Proposed Guidance on Dose Limits for Person Exposed to
Transuranium Elements in the General Environment."
8.9 Conclusion
In summary, the U. S. Environmental Protection Agency does not
recommend that soil sampling and analysis methods be used as the
primary means of implementing requirements which specify inhalation
dose limits to members of the general population. Such methods suffer
from the inherent problem of relating the soil and air concentrations
of the contamination and, at best, can only serve as a useful
indicator or screening tool. The results obtained by the different
methods for soil sampling and analysis are not generally comparable,
and must be specified in terms of the procedures used.
Any of the commonly used, or proposed, soil sampling and analysis
methods can be utilized for evaluation studies and provide useful
data. Application to implementation of public health protection
criteria of any soil sampling method is limited by the fact that
environmental pathway and transfer factors must be determined on a
site-specific basis and validated with extensive experimental data.
The usefulness and confidence one can place in the results obtained by
any particular method is therefore directly related to the extent that
the method furnishes reliable data useful for the estimation of
adverse health impacts on individuals in the general population.
212
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In the view of the Agency staff, the method proposed by Dr.
Johnson does not satisfy technically acceptable criteria for adequate
evaluation of a potential health hazard to individuals or population
groups. It does not provide the required data for calculation of lung
dose rates by methods recommended by the International Commission on
Radiological Protection, incorrectly classifies the sizes of particles
with respect to inhalation dynamics, and greatly overestimates the
intake of respirable dusts by an individual. We therefore conclude
that the proposed method should not be used to assess the inhalation
hazard to individuals living in close proximity to environmental
contamination.
273
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EVALUATION OF THE HAZARD TO RESIDENTS Or AREAS CONTAMINATED WITH PLUTONIUM
Carl J. Johnson, M.D., Jefferson County Heolth Department and the University of Colorado School
of Medicine, Lakewood, Colorado 80226
Abstract
ptufonium oxide particles in fhs fine participate soi! fraction of surface cJust ore subject to suspension
by air currents and are a potsntiai health hazard to humans because of inhalation. This respirabie paiijculafe
fraction has bean defined us the particles - 5pm. The respirabie fraction of surface dust can be fepcrofeo
by ultrasonic dispersion and a standard wafer-sedimenfaHon procedure. We'believe this rnelhod of evaluation
defines more precisely the potential health hazard from plutoniufn-contaminoted soils then other methods.
With this method, pi uranium levels in ths respirable-particulate fraction of offsife soils located downwind
from a plutoni'jrr.-processing plant (Rocky Flats) were found to be os much as 380 tiroes the background level.
Risk estimates for residents may be made by cciieolation of dosage .related to quantities of respirable dust
inholerl cnnua'iy. For example, in residential areas with 20-disintegrations of p! uranium par minute per
gram of respirabie dust, or person may inhale and retain 10 to 12 grams or mere'of resusoended d'ost (100
picocuries) ovar a period of months or years and may receive about 0.1 rem to fhs Sung, 4-5 rern fo rhe
frachio-bronchia! lymph nodes, and 0.12 rem to the iiver. The gcnadal and 'eta! dose is difficult fo evaluate,
butp'ufoniom has be-.n found in gonada' tissue and .in the fetus. This amount of exposure fo one million
people cculd re$»H in cbput 160 excess deaths duo to leukemia and a total increase in ail neoplasms of perhaps
} io 3 per cent over c period of 70 years. This may include from 6 fo 1COO excess cases of bone ccncer (this
largts range is due f» two point-; of view). The incidence of all genetic diseases may increase by ,1.5%
and ill health related ro chromosome mutation by 10%, for oil succeeding generations. Other factors, such
as the ingrowth of Axericium, use of etiolating agents in fertilizers, eic. may change the nature of the risk
and actually increase the incidence of effects. These considerations demonstrate a need for the establishment
of conservative Units or, psrmissabls soil contamination by piutoniurn in reiidsnlia! areas.
introduction
Plutonium oxic's particles deposited on the ground surface by accidental spills or atmospheric fallout
(Table 1) ere. subject to resuspenston by wind or orher means. Particles in the size range of 5 jjrn end srndier
ore considered to be of rsspirabie si;:e because when inhaled they may be retained v,;ihin the^yng1'1-. Most
of iho plufonium oxide particios released offsife by r.ucienr installations are in this size ranae^/'. This paper
describes a method of measuring the concentration of plufoniurn in the potentially respirabie surface o'usr and
discusses thfe potential health effects cf exposure fo such dust.
Sample collection and processing
In our tiudy crsa (downwind from rhe Rocky i:T«Tj^plant) sirss for sampling wer«» selected foilowing '•
guidelines propowd by the Atomic Energy Commission^'1. A composite sample of the loose, su.-ficic,-! (about
0-0.5 cm dsep) soii i~o.old lettiing velocity v/os computed from Stake's eqtiaiicn using an effective dinmstcr
274
-------
i»f 5 pfh and a density of 11.36 g/cnv* (plutonium -oxide). The size fracfion-thus collected includes other
mineral parades with equivalent settling velocities that have some combination of smaller density and
forger diameter. The collected fraction was freeze-dried and anaiyred for plutonium by radiocheir.ical
procedures'''/^/. Contamination of off site soils in the study area (an area proposed for residential develop-
ment) was found to be as great as 330 times the background value. We believe that the concentration of
pfutomurn in the respircble fraction of surface dust, as defined here, is an index that can be more readily
related to the potential health hazard than other indices utilized for this purpose. , ' • I
' " • -•..--.- Particle Size and Activity • • ,. •
Relationships between particle size, volume, mass and radioactivity :are shown in Table 2. A particle
of plutonium oxide one pm in diameter weighs about six millionths of a mierogram '(j.>g). This particle is " '
very small but has an activity of 0.3 picocuries (pCi) or about one disintegration every i .5 minutes. A •
particle S.yrn in size has'a mass of .007 pg. This particle is also of respiroble size and will have an activity
of about 4.1 pCi or some 90 disintegrations per minute (dpm). One hundred of the 5 pm particles together •
would weigh about 0.07 pg. Since plutonium has a biological activity 15 or more fimes as great as radium,
this mony particles of plutonium oxide may be similar in effect to 0.5 yg of radium, the smallest bone -doss
found associated with osfeosarccma in radium dial pamrefsv'. Although plutonium may be present in con-
taminated crsas offsife in extremely small quantities, this may be sufficient to produce bone cancer and
other iypes of rumors.
,- Estimates of Dosage end Effect ... •
The recommended dose limit of plutonium 239~(occupatidnal exposure)-to lung is at present 15 rem/yecr
or 16,000 p.Gi. 'This maximum permissable annual dose (MPAD) is equivalent to about 400 five urn particles,
or a totol moss of about 0.3 jjg of plutonium oxide. A single particle of plutonium oxide 40 pm in size has
more than this much. activity and is within the range of atmospheric dust (0.3 to 100 pm). A particle of this
sire might not be retained in the respiratory tract, but could lodge in an abrasion or other wound.
Meyers gives evidence to support a recommendation that- a much mere realistic limit than the present :
1.5 rern MPAD for lung burden is the "maximum perrnissable pulmonary Lymph node burden" which is placed
at 230 pCiOC). The maximum !ung level that cou'd produce this is 67 pCi. Meyers points out that (his is
less than 0.5% of the currently accepted MPAD (occupational) of 15 rems for the lung. The inhalation and
retention of two 5 pm particles annually would exceed this amount. Morgan also demonstrates the? the
present limit for exposure to plutonium may be too high by a factor of 240 or more, in* relation to potential '
effeuis on bcne'' '.'. Again, two of the 5 pm particles would exceed this more conservative dose limiti
.The relative risk of inhaling and retaining plufonium oxide particles in reference to the amount-of
pJutonium in the respirable dust is illustrated in Table. 3. A single.4 pm particle may produce about 50 a'pm,
equivalent to about 20 millirems. One such particle in 25 grans of respirable dust will produce an average
activity of 2 dpm/gram of dust. If g person hos inhaled and retained 12:5 grams of dost, he has a 50% chance
of inhaling that one 5 pm particle of piufonium'oxide. However, the particle may be in the first bit of dus^
inhctied or in the last bit. The probability is one in 1CO, expressed -in -the table as p=.01, that .?f 'he -inhales
only 1/4 gram, that he'ruuv inhale rha 5 prrrpciticle. Retenricn of two of these particles., or an eqyivolenf
lorger number of smaller onrticiGs/wo^iQ exceed dose limiti propose.d by Morsaiicnci Meyers. It may be
that in the very first whiff of d'jst (25 milligrams) that he may inhule the particle.. The chances are about
one in one thousand that this could occur, in -a total 'population, of 100,000 or more who could be housed .
in a contaminated area such as that near the Rocky F!afs plar.f, iheso od
-------
Incidence v/ou'd be 0.1% or one cose per thousand biifhs in ihe first generation, and 0.75% or about one
btrfh in 133 for succeeding generations. The committee also believes that between 5% arid 50% of ill heal Hi
Is proportional to the mutation rate. This much radiation per generation cculd eventually lead to an in-
crease of 5% in the ill health of the population.
Estimates of excess rates of cancer may a'so be calculated in the following manner, again referring
to an onaa with 20 dpm/g of plutonium in respirable dust. The following example is the calculation of the
Increased rate of bone cancer in such a- contaminated area.
1 rom x one mil Men persons''3) . 1000 pCi (infra1 ed)Q4) . . 2.2 a'pm . 1 gram - 3.4 grams dust
10 excess bone cancer cases 3.2 rem (bone) .1 pCi 20 dpm 1 excess bone cancer
per million persons
OFfsiro lands in our study area (downwind from the Rocky Flats plant) have levels far in excess of this amount,
and a development project five kilometers east of the plant site has levels that approach 20 dpm/g in respir-
aWe dust. V/e see that about 3.4 grams of such dust (32 pCi), inhaled and retained, may result in one
excess bone cancer case in a population of one million people over a life span. Other effects from this
dbsoga of radiation rpoy be calculated in a similar manner. Such effects would be multiplied for each
cddStiofXi! 3-4 grams of respirable duel in'r.alea'*. Over a period of months or years a person may inhale
and reiuin 10 fo 12 grams or more of rasuspsnded dust (100 pCi) an-J may receive about 0,1 rem to the lung,
4-5 rem to the trachlo-bronchial lymph nodes, and 0.12 rem to the liver. Thw gcnadai end feral dose is
difficult to evaluate, "but plutonium has been found in gonadal tissue and in the fetus. This amount of
exposure to one million people could result in about 160 excess deaths due to leukemia ancl o tofai increase
In all neoplasms of perhaps 1 to 3 per cent over a period of 70 yeais''™. This may include from 6 to 1000
excess cases of bone cancer (this large range is due to two points of view).' '<• 'A. The incidence of aii
genetic a'i<»asQS may increase by 1.5% and ill health related to chromosome mutation by 10%, for all
succeeding generations' '. Other factors, such as the ingrowth of Americium, usa of chsiafing agents in
Fertilisers,, etc. may change the nature of the risk and actually increase the incidence of offsets. Because
plutonium is stored in the body to a considerable extent, a person living several yea's in such an area may
inhale and retain enough plutonium to produce these effects even though hs may 'nave ihs cre.a.
•Effects are more likely to occur Ir. the fetus, the child, and in persons with increased susceptibility to
neoplasms. 'There is evidence ihat smaller doses of radiation are inora harmful per cad then would b<; expected.
Stewart and NecO end others have shown a greater risk of leukemia per rod at low intrcuferine exposures,
0.25-0.5 rad, than at higher doses to the fetu.A'*'''. One rem (equivalent to 25 5^m particles) may cause
an 80% increase in mortality from childhood cancers after fetal exposure, and a 0.9% increase in recognized
"spontaneous" abortions^3).
Conclusion
Federal guidelines are being promulgated bylhe U.S. Environmental Protection Agency to guide the
use/ treatment., and lehabiiitctfon of land contaminated with plutoiiium. At the present rims there are areas
In the United States which have levels of conrsminafion of 19 dpir/3 in respirable dust which are presently
being used or devsloped for residential purposes'10). The imporfence of the esro-blishment of o maximum
allowable level of contamination based on the concentration of plutonium in the respirabie Just mt'it be
emphasired. This level may be appropriately sef as low as 2 dpm/g, since there is sufficient evidsnca to
Indicate probable health effects ar the 20 a'pm/g level, and possibly ar levels below this figure.
As much as 67 mg of du«.t per cubjc meter (mg/m^ ) hcs been measured downwind from farm equipment.
An average value of 0.1.75 mj/M° was observed in Denver In 1970-73. Average annual respirator)'
volume is about 8000 m^ for an adult.
-nr
t b
-------
References
1. Ar^?fion D.O.: Chronic non!yberculous respiratory disease. In Claik, D.W. and MqcrVahon, B. (Ed.) Preventive Medicine. J. &
• A. Churchill Ltd.. London. K57.
Eider, J.C., Gonzole:, M., and Etlinger, H.J.: Plutonium ooroiol si?c characteristics. Health Fhy;ics, 27: 45-53, July, 1974.
2.
3.
4.
5.
Measurements o; radionuclic'rts in the environment, sampling o:id onp'ysis of plutonium in soil. Stor.dards for protection against radiation:
U.S. Energy R?s. Dev. Adm. Regulatory .Guide 4.5, 10 CR, part 20, Federal Register 20, p. 106, 1974. ,
• Johnson, C. J., Tia'ba!!, R.R., end Severson, R.C.: Plutonium ha/ord in respiroble dust on the surface of soil . . Science/ 193: 48S-490, }9~i
Kunre,, G.W.: Prctreatmont for mineraloqical analysis, in Block, C.A., atid others, ed., Methods of soil analysis, part 1: Madison,
Wis.f Amer. Soc; Agronomy, 563-577, 1965.
6. Day, P.R.: Particle fractionation and particle-size analysis, jn_ Block, C.A., and others, ed.. Methods of soil analysis, port 1:: Madison,
Wisi, Amer. Soc. Agronomy, 563-577, 1965. " '
7. Tolvitie, N. A. : Rcdiochemical determination of plutonium in environmental and biological samples by ion exchange. Anol. Chem.:
43: 1827-1830, 1971.
8. _ __ : Electrcdeposition of acfinides for alpha spectrometric determination. Ana' . Chem.: 44: 280-283, 1972.
9. Mortland, H.STond Humphries,, R.E.: Osteogenic sarcoma in dial painters using luminous paint. Arch. Path., 7:406, 1929.
10. Meyers, D.S.: A plea for consistent lung burden criteria for insoluble alpha-emitting isotopes. U. of Col ., Lawrence Livermore lab.
Health Physics, June, 1972. .
11." Morgan/- K.Z.: Suggested reduction of permissoble exposure to plulonium and other transuranium e'emenfs. Am. Ind. Hyg. Ass. J.:
567-574, August, 1975. ' • : .....-'...'...
12. Anon.: The effects on populations of exposure to low levels of ionising radiation. , Report of the Advisory Committee on ihe Biolonical
Effects of lonmng Radiations, Division of Medical Sciences, National Academy of Sciences. National Research Council , Washington,
D.C., 20005, November, 1972. .
13. Anon.: Approaches to population protection in the case of nuclear accidents. (Unpub.) Office of Radiation Programs, U.S. Environmental
Protection Agency}.. Washington, D.C. 20460. * ' . .
14. Thompson, R.C.: Implications with respect to the Protection Criteria. Plutonium and other Transuranium Elements: Source1:, environmental
distribution and biomedical effects. Publication \VASH 1359. U.S. Atomic Energy Commission, December,, 1974.
15. Stewart, A., Webb, J., and Hev.-ett, D.: A survey of childhood malignancies. British Med. J., 1:1495, 1958.
16. Johnson, C.J.: Survey c* land proposed, for residential development east of Rocky Flats, for plutonium 239 contamination of respirable dust
on the surface of the Soil, and proposal of a new standard to define the potential airborne- piutoriium" particle hayard.in terms of concen- ,
tration of plutonium in respircble dusl. Report to Ihe Jefferson County Commissioners and the Colorado State Health Departnent. Un-r ,
published. September?. 1975. : • -
17. V/renn, M. E.: Environrr.entpl levels of plutonium ond the transplutonium elements in plufonium and other transuranium elements: Sources,
environmental d'slribufion and bibmedical effects. \VASH 1359. U.S. Atomic Energy Commission, December, 1974 (Testimony before
on Environmental Protection Agency Hearing Board, Washington, D.C.). • '
IP. Bennett, B.G.: Environmental Pathways of Transyrcnic Ele-nents. WASH 1359 (ibid.) ' • • .
Acfenciv/ledgement: Valuable assistance of R.R. Tidball, PH.D. ond RfC. Severson, Ph.D. of the U.S. Geological Survey in the design and
ejcccution of the survey, end revitw of the report. •....'"
. Table 1 _ Table 2 o
ConcenSrptions of Plulonium in Soil Plufonium oxide particles: Volume in cubic micrometers ((Jrn")
mass in micrograms (HQ) and radioactivity of plufonium 239
Disinlegrofions in picocuries fpCi) and disintegrationtioer minute (dpm)
Location per minute/gram ' by particle size .in pins, for sphere-shaped particles.
Worldwide (fallout) 0.0 to 0.4
Control Now Mexico (Trinity)* 0.3 to 22.2
Nevada Test Site * 0.2 to 22.2
Los Alamos Scientific Laboratory* 0.01 to 111
Rocky Fiats* ' - 0.4 to 211
Bikini Atoll 2.9 to 422
Polomores 0 to 3996
EniweloU Atoll :" 76 to 7104
*Offsite Adapted from Ref. 17
:, Toble3
Relative risk of inhaling and retaining
ptotonium particles, by level of radioactivity
of respirab|e dust end quantity of contam-
inated dust inho'ed.
Activity of Assuming one particle,
pfutonium irr grams dust inhaled ond
respiroble retained to retain £3 c!pm*
dusf P--.S o=.01 P7.W1_
Particle
SI 76 in j-fftl
40
5
4
2
1
Volume
pm-*
33,510
61
34
4.2
0.5
'.Mass
^g
'0.38
6.7X10"3
3.8x10"^
4.9xlO~5
. 6.1xl6"6
Table 4
Dose-equivalent in rem per 10CO-
picocuriss of plutonium 239 inhol
Activity
pCi dpm
21,000 46,000
• 41 90
21 46
2.6 5.8
0.3 .0.7
Toble 5
Estirmted rates of plutor.ium-ind'jced ccncer aid
hereditary injtj.y per million persons-rems
Prediction
based on Neoplasm Hereditary
Organ
2 dpm/g
5 dpm/g
10 dpm/g
20c'pm/g
12.5
5
2.5
1.2
0.25
0.10
0.05
0.02
0.025
0.01
0.005
0.002
Lymph Node*
Bone
Liver
Kidney
Gonods
Plutonium 23v
0.9
43.7
3.2
1.3
0.2
0.05
data from: Lung
A.Vm*.
Dog
Rot
16-110
70
60(700***)
Bone
2-17
70 ,
10
20
50*
> may be produced by cnn r-ar(!c'c
cbout 4 pm in dlo.T.eier, end is equivalent
to oboat 20 miliireiiiv.
Assumes thai particles arc rctoir.c.i
for o lo.'igoi t-cno'J of. time in t..o
(ong. {Adapted hum Hef. IS)
* BE1R Report (olso 1-7 cases of liver cancer
per.million per:on-rems)
** 50 ca;es ptr irillicn person-rems for
immcdiatt? fqnijly, SCO cq'
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Enclosure II
DEPARTMENT OF ENERGY
COMMENTS ON DECONTAMINATION COSTS
DISCUSSED IN THE EPA PROPOSED GUIDANCE ON
DOSE LIMITS FOR PERSONS EXPOSED TO TRANSURANIUM ELEMENTS
IN THE GENERAL ENVIRONMENT
-------
CONTENTS
I. APPROACH
II . COSTS AND ECONOMIC IMPACTS ...... ......... II-l
GENERAL CONSIDERATIONS ....... .......... H_l
COST ESTIMATION FRAMEWORK ..... ..... .... .11-5
COST DATA ....................... n_8
COST ANALYSIS .... ................. H-15
REFERENCES ....................... H-25
APPENDIX A - SITE DESCRIPTIONS . ...... , ....... A-l
APPENDIX B - SAMPLING ............. ....... B-l
APPENDIX C - REFERENCE DECONTAMINATION PROCEDURES ...... C-l
APPENDIX D - UNIT COST DETERMINATIONS ......... . . . D-l
APPENDIX E - ECOLOGICAL IMPACTS ............ ... £-1
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ESTIMATE OF POTENTIAL COSTS
OF HYPOTHETICAL CONTAMINATING EVENTS
I. APPROACH
In processing, transporting, and using transuranic materials, stringent
measures are taken to prevent accidental releases of the materials to the.
environment. Should accidents occur, similar rigorous attention would be
paid to minimizing risks and injuries to people and property in or concerned
with the affected geographic areas. Nevertheless, it is reasonable to examine
the potential effects that application of the proposed Guidance might have
on the costs and on the economic and ecological impacts associated with decon-
tamination procedures.
For purposes of conducting such an analysis, hypothetical accidental
releases of transuranic materials were assumed to have occurred at each of
three real, but not identified, sites in the United States. (See Appendix A
for descriptions of these sites.) The analysis was,based on the alternative
assumptions that l-km2 and 10-km2 areas were found after the hypothetical
contaminating events to require remedial treatment under the proposed
Guidance. Cost estimates included expenses expected to be incurred in the
conduct of an appropriate sampling program (described in Appendix B). The
sampling program would be needed to define these areas, determine the types
of treatment required, and assess the effectiveness of these treatments after
their application. Cost estimates were made in each instance for application
of a variety of treatments that would be acceptable under the Guidance,
including:
• in-place stabilization by the application of a relatively impermeable
cover and by limiting area access and use
* Dilution by plowing or other similar techniques
« Disposal by removal of surface soils and burial either onsite or in a
designated waste storage repository.
1-1
-------
Application of these treatments was assumed to be accomplished through a
series of steps appropriate to the conditions at the sites (see Appendix C).
Costs for cleanup and for long-term stabilization and access-restriction
alternatives were calculated by estimating unit costs for all critical compo-
nents (Appendix D), then applying these costs to the specific circumstances
at the respective sites. Activities assumed, for purposes of cost estimating,
to be involved in the treatment of contaminated areas included initial sam-
pling and monitoring to locate and assess the degree of contaminated soils
and materials; population evacuation, maintenance, and radiological monitor-
ing; plowing or removal of contaminated vegetation and soils, and cleaning
of structures; temporary storage of contaminated materials; packaging, trans-
port, and permanent disposal of contaminated materials; post-cleanup monitor-
ing; and restricted area maintenance. In addition to direct treatment costs,
estimates of costs from the interruption of economic activities were also
made.
The analysis of costs and economic impacts is presented as the main body
of this t-eport because the estimates of these impacts appear to be the most
significant results of the study. All other material that supports the
analysis of cost and economic impacts follows in Appendices A-D. Also
included is Appendix E, which presents a general description of probable
ecological impacts. Assumptions basic to the study are presented in Table 1,
which appears in the Costs and Economic Impacts Section.
1-2
-------
:.-.:.. - n. COSTS AND ECONOMIC IMPACTS ,
This section presents an analysis of possible costs attendant, to decon-
tamination and related activities that might be necessary following an
accidental release of transuranic materials. : .
A number of factors would affect these costs. The equations developed
in this section account for the major factors, including the size of the
area affected, the length of time that the area would be affected, and the
type and level of normal economic activity in the area.
.... ' . •••.;;•.
GENERAL CONSIDERATIONS . .
The analysis of costs presented here is sensitive to a number of
assumptions, exclusions, and simplifications. A list of the principal ones
is provided in Table 1 for convenient reference. They are"developed more
fully in the text that follows.
Decontamination of areas impacted by a release of transuranic material
might be accomplished under the Guidance in several ways, including site
restriction, stabilization, earth removal, or dilution through plowing.
Buildings and other structures would have to be handled by other techniques.
The costs and effects of these methods would differ for any given situation.
The decontamination of a site might be handled best by a combination of
techniques applied to different portions of the total area to achieve the
desired result. Since the number of potential combinations for any site
would be large, however, the analyses reported here assumed use of only one
treatment at a time for all relevant portions of a site. The cost estimates
/derived from application of the various methods on each site were then
compared to suggest treatment cost ranges.
II-l
-------
TABLE 1. Important Analytical Assumptions, Exclusions, and Simplifications
1
2.
3.
4.
5.
6.
7,
8.
This study considers potential costs associated with hypothetical
accidental releases of transuranic materials. It does not consider
any actual contaminated sites or releases associated with routine
facility operations.
The study does not consider effects associated,with the events occurring
during and immediately after the accidents; it deals only with the effects
of treating the contaminated areas resulting from the accidents. Treat-
ment is taken to include, however, both initial sampling and any necessary
evacuation of people from affected areas.
The site descriptions were based upon real, uncontaminated areas;
therefore, real land use, economic, and ecological data were used in
the analyses.
Cleanup cost estimates were based upon the assumption that adequate dose
rate reductions would be achieved on the first application of the
selected treatment to each contaminated area. Not included are the
costs that would be incurred if the treatment had to be repeated to
reduce contamination to acceptable levels.
Costs for packaging, transporting, and disposing of contaminated earth
removed from an area were based upon removal of soil to a depth of 5 cm.
Estimates derived in this study represent total costs for dealing with
the accidental releases in compliance with the Guidance, rather than
marginal costs representing the differences between working with and
without the Guidance. The total-cost approach is consistent with the
approach taken by EPA in the estimates provided in the Guidance.
The estimates were calculated from unit costs for materials, equipment,
and labor, based upon national averages.
The costs of having crews and equipment idle while awaiting post cleanup
sampling results were not included in the estimates.
9. Costs for shipment of decontamination equipment or crews to affected
areas were not included in the estimates.
10. The population located within areas designated for treatment was assumed
evacuated as a part .of the treatment process. It was assumed that the
average evacuation period would be 30 days.
11. No cost estimates were included to cover expenses associated with environ-
mental impact analyses, environmental impact statements, or potential
litigation arising from possible contaminating events and subsequent
cleanup activities.
II-2
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TABLE 1. (contd)
12. Psychological trauma and othfr nonquantTflable effects of treatment
measures for qontaminated areas were notassessed.
13. Health effects from radiological exposures or other hazards associated
with treatment of contaminated areas were not estimated.
II-3
-------
The Guidance specifies that remedial treatment of contaminated areas *
would be necessary wherever the dose rate to individuals residing in the •
affected areas would exceed 1 mrad/yr to the pulmonary Tung or 3 mrad/yr '<
to the bone. The Guidance also indicates that areas in which the transuranic
2
contamination in the top cm of soil did not exceed 0.2 wci/m could be
considered safe without remedial treatment. For purposes of the illustrative !
analyses conducted in this study, it was assumed that an appropriate'
sampling program (for which costs were included) had led to the delineation
of areas requiring remedial treatment, based upon these criteria. Costs K
and ecological effects estimated for each of the three reference sites
considered were based on the alternative assumptions that the sizes of
22
the areas requiring treatment were 1 km or 10 km .
The costs of remedial treatment of contaminated sites would be
dependent upon factors heavily influenced by either area size or the time
^required to effect the treatment. The main cost elements that would be
more affected by time than by area are the possible costs of evacuation
and production loss. While initial evacuation costs may be thought of as
an independent factor, the costs to the population during decontamination
would be directly dependent on the length of time involved. The monetary
loss experienced by nonagricultural workers, for instance, would depend
largely on the amount of time these workers were prevented from working.
Agricultural production losses would depend on the time required to bring
land back into production at a level equal to that prior to contamination.
These losses were estimated here on the basis of average production levels
and product values. The actual losses from a. real accident would vary
greatly from site to site and from one commercial .activity to another within
sites.
The cost calculations presented here were formulated on the basis of
estimated average costs for wages, materials, equipment, evacuation expenses,
2
etc., required to treat each km of affected land of a given type or use.
While one might prefer for the sake of greater accuracy to apply scale economy
and marginal cost principles, their use would necessitate firm assumptions on
cleanup timing and on equipment and Tabor availability in the affected area at
II-4
-------
Ithe specific time they were needed. Unless consistent for ,all cases
Istudiedvjthese assumptions would detract from the usefulness of the analyses
pf various cases fprr comparative 'purposes, ft 'is not expected that the error:
Jin cost estimates resulting from the,exclusion of scale economy and marginal
cost principles was unacceptably .large, given the purposes of the .analysis .
'and other necessary assumptions, exclusions, and simplifications that affected
the results.
COST ESTIMATION FRAMEWORK .
Once areas and contamination levels in a situation have been identified
and treatment techniques chosen, the total costs of decontamination of an
area may be estimated by the cost equation:
TC,
/Tr.-1-alv :
(Sst) •
'
ET
KP
n=l
M
KP
n=l
S
/ Population \
( Hon1tpr1ng.& •).
\Decontam1 nation/ v " iamp ' ' ng '
111 ,
DKe
+ (Decpntamination) + (Temporary Burial)
+ (Final, Buria.l)
>Sl
-r.
/Rural Land \
\Reclamation/
/Urban Land \
IReclamation/
+ X, I .K 1
r=l
/AgriculturalX
+ ( Production )
. \ Loss /
+ (Manufacturing b Other Production Loss)
II-5
-------
where:
TC, = Total cost of decontamination-related activities and
compensation
E 3 Evacuation cost per capita per day
M - Cost per capita for population monitoring and decontamination
S = Cost of preliminary site survey and sampling
2
P s Population per km
Q = Cost of surveillance
T = Estimated time to complete decontamination
2
K = Land area in km
n = Number of land areas to which a unique set of decontamination
procedures is applied
r = Rural
u * Urban
K = Area in km where earth removal is used
e
O ' ,
A = The cost per km of each unique set of decontamination
procedures (labor, machinery and supplies)
2
L s Land reclamation costs per km
2
D = Temporary burial site costs per km (stabilization plus
monitoring costs)
2
F = Cost of final disposal per km
X,, X2 and Xj = Production losses (agricultural, manufacturing and other
t in that order). ,
In cases where the total decontamination costs were found to exceed
the estimated value of the area, stabilization of the contaminant and
restriction of the site might be desirable. If so, the following cost
equation would be appropriate to estimate total cost:
II-6
-------
TC,
ET
MKtP
: Trt.al / Population V
I... I0"' = (Evacuation) +( Monitoring & ) >
; LOSu
\
r (Surveillance)
/
RKtP
(Z + Y..+ V)K.
\ Surveillance /
where:
TC2 = Total cost of site-restriction-related activities and compensation
E = Cost of evacuation per capita
M = Cost of population monitoring and decontamination per capita
S = Cost of preliminary site survey and sampling
Q = Cost of surveillance
2
Kt = Total area to be restricted in km
T = Time until decision is made to relocate the population
2 . . .-..•. ••.-.•
P = Population per km ';;,.,.
R = Per capita relocation costs including compensation for produc-
tion losses
2 ' ' ''' ''
Z = Condemnation value of site and buffer zone per km
Y = Cost of site stabilization per km
2
V = Present value per km of site surveillance.
Where a situation dictated restriction of part of the area and decontami-
nation of the remainder, the two cost equations could be applied to the appro-
priate portions of the total area and summed to estimate total cost.
11-7
-------
COST DATA
$561,500/knT
,2
Using the treatment measures assumed to be applied to the sites of
hypothetical transuranic contamination, point estimates were found for'the
costs incurred from the time of the accident until the land was restored
to its original use and disposal of the transuranic wastes was complete.
The unit costs (including overhead) given in Table 2 were used to compute
the site cost estimates. A discussion of the procedures used to determine
these unit costs is presented in Appendix D.
In order to find the cost of the set of procedures called for in the
decontamination of a given land type, the land area in one use (Kn), shown
in Table 3, was multiplied by the sum of appropriate procedure unit costs (A(
from Table 2. Examples of the estimated costs of decontamination procedures
(in 1977 dollars for earth removal, not including reclamation) for various
land types are as follows:
Forests
Cornfields
Plowed Farmland
Pasture
Residential Area
Industrial Area $897,000/kmt
To derive the cost of decontaminating commercial and residential areas,
some assumptions on the composition of these areas were made, as presented
in Table 4. The production-loss and real estate values used are given there
also. While production losses and real estate values for agriculture would
depend on the land area affected by the contamination, commercial production
losses and commercial real estate values would depend both on the population
employed and on. capital investment. Since capital investment data are not
readily available, however, the cost estimates here were computed on a per
capita basis.
From the unit costs and assumptions regarding land use, costs were
estimated for all aspects of decontaminating and managing each s1te» These
are given in Tables 5 through 7, using earth removal on the contaminated soil
areas. The total cost for each site is rounded to the nearest $100,000.
$423,000/km^
$403,000/kmJ
$403,000/km*
$611,000/km2
11-8
-------
TABLE 2. .Unit Costs for Area Decontamination and Management
Two Weeks of Water, Fixation ,
Long-Acting Stabilizer
Corn Removal
Other Crop Removal
Earth Removal (Grader)
Earth Removal (Front-End Loader)
Earth Removal (Manual Labor)
Field Sod Removal
Lawn Sod Removal '
Vacuumized Sweeper
Fire Hosing
Homes
Population Monitoring & Decontamination
Evacuation, Including Room, Board,
Transportation and Personnel(2, p. 12-3)
Lawn Resodding
Topsoil Replacement
' Erosion Control
Fertilizer + Seed (Materials Only)
Temporary Storage Sites (Except Land Cost)
Plowing
25 cm
1 m, Tilled Land
„ ,1 m. Pasture, Including
Reseedingd, p. 12-11)
Surveillance (Based on Perimeter Length)
Commercial Areas
Disposal (1000 Miles of Transportation,..., ,
2-in. Soil Removal, Federal Disposal Site)
Biobarrier (Labor and Materials)
Fence (Based on Perimeter Length)
Present Value of Future,.Surveillance
44,500/km
62,500/km2
12,000/km2
2,500/km2
137,odo/km2
250,000/km2
430,500/km2
137,boo/km2
17T-,000/km2
24,000/km2
3d,0.00/km2 -
200/home,
300/person
15.00/person/day;
945,,000/km2;
1 J83,500/km2
154,500/km2
48,506/km2
2iOOO/km2
.. 2,OOQ/km'
JZl.OOO/km2
3,500/km
543,500/km2
10,752,
,:- :.35-,0007km
.;, .100,000/km,
Cost Plus Burden
$ 73,500/km2
103,500/km2
, 20,000/km2
4,000/km2
226,0007km2
'' 412,500/km2
710,500/km2
226,000/km2
282,0007km2
40,0007km2 --
50,000/km2
350/home
1,275,500/km"
^s597,500/km^
208,500/kmJ
65,000/km2
3,5007km2
3,500/knT
34,5,00/,km2
- T50,060/km2
; ,6,000/kni
: . 897iQOO/km2
119,200,0007km2
17,742,0007km2
-, •.47,000/km
NOTE: Burdened costs include overhead (25%), loss of efficiency due to protettive
clothing (30%), workmen's compensation and social security (10%), except for
land reclamation costs which do not require?protective clothing and ioclude
only overhead and social security. All unit costs are rounded to ^
•.-•-'• nearest $500. ; . •/-;'- •-.,•-';••-• .;•••;'.•&:.-•**•;;•-•-•- •••^-••.-.?-.-•:; ....'^ r^-.
ri-9
-------
TABLE 3. Land-Type Breakdown by Site for 1.0-km2 and 10.0-km2 Areas3
Reference Site One
Corn Fields
Plowed Farmland
Hay and Soybeans
Pasture Land
Residential Area
Wood!ots
Industrial Areas
Population
Perimeter
Reference Site Two
Forest
Shoreline
Residential Area
Population
Perimeter
Reference Site Three
Pasture Land
Field Crops
Orchards
Ditches
Residential Area
Population
Perimeter
1.0 km'
10.0 km'
0.37 fair
0.25
'0.13
0.11
5 Homes
0.09
0.05
15 Persons
2.5 km
0.21 km2
0.22
0.57
2269 Persons
2.5 km
0.58 km2
0.31
0.07
0.03
0.01
39 Persons
2.5 km
3.70 km-
2.50
1.30
0.60
1.40
0.30
0.20
5475 Persons
15.1 km
3.96 km2
3.96
2.08
8202 Persons
15.1 km
5.80 km2
3.17
0.70
0.30
0.03
120 Persons
]5.1 km
a)since these sites are real, the mix of land types and the land uses
varies with area size; therefore, the composition of the 10.0-km2
area at each site is not necessarily proportional to the composition
of the 1.0-km2 area. '
11-10
-------
TABLE 4. Assumed Values for Derivation
of Decontamination Costs
Average annual value of production of agricultural land per km = $24.000.
This figure was computed from the value of cash receipts plus home consumption
for U.S. farmland given in the 1976 U.S. Agricultural Statistics^) and adjusted
to 1977 dollars.A2-yr loss of production is assumed for earth removal and
plowing to 3 ft.
Median value of a single-family dwelling— $40,000. This figure was taken from
a 1976 study by the MIT-Harvard Joint Center for Urban Studies and adjusted to
1977 dollars.
Value of commercial land and structures = $5,000 per capita. This figure was
computed from a National Bureau of Economic Research publication'*) and adjusted
to 1977 dollars.
Average value of agricultural land and buildings per km - $148,000. This figure
was taken from the 1974 Census of Agriculture^) and adjusted to 1977 dollars.
Manufacturing production loss = $250.value added per capita per month. From the
City and County Data Book of 1972,t6/ adjusted to 1977 dollars.
Other production loss = $300 per capita per month. This figure was taken from
the-1970 Census of Population^7) information on earned incomes, adjusted to 1977
dollars.
Decontamination procedure period = 1 year.
Evacuation period = 30 days.
Composition of residential areas: (taken from WASH-HOOT1' p> 12~12')---
57% lawn and fields 20% pavement 23% home and roofs
Composition of Commercial areas; (taken from WASH-1400 r1' p* 12~5V
50% building 50% pavement
Relocation costs per capita = $3,500. This cost was taken from WASH-1400,
(Ref. 1, p. 12-5) adjusted to 1977 dollars.
Final disposal costs are computed on the basis of figures given in BNWL-2210.,^8^
Tri-State Motor Transit Company,(9) and GESMdO°). The transportation
distance is assumed to be 1000 miles (1609 km) for all sites.
2
Residences per km = 1235 and persons per residence = 3.2. These figures,
assumed for the site of each accident scenario, correspond to the medium-
density residential pattern described in WASH-1400.(Up. 12-4)
u-ir
-------
TABLE 5. Reference Site One: Decontamination Costs
for Earth Removal TO
and 10.0 km2
Cost Element Description
n
ET £ ICP Evacuation
n=l n
M S K P Population Monitoring
n=l n and Decontamination
S Survey and Samples
Q Surveillance1
n
£ K Ah Decontamination:
n=l n n Corn Fields
Plowed Farmland
Hay and Soybeans
Pasture
Woodlots
Residential Areas
Industrial Areas
DK Temporary Storage
e
FK Permanent Disposal
Z K L Land Reclamation
u
Z K L Lawn Resodding
r Production Losses:
v r v T flnririilt.iiral
\r Areas or i .u K
Costs (
1.0 km^
$ 6,800
4,500
161,500
15,000
156,500
100,800
52,900
44,300
50,500
1 ,800
44,900
3,300
113,240,000
1,616,500
—i—
45,600
$ 1977) .
10.0 km^
$ 2,463,800
1,642,500
1,069,200
90,600
1,565,100
1,007,500
529,100
241 ,800
168,500
855,400
269,100
32,200
1,096,640,000
16,039,900
1,020,400
403,200
X3 E
3 n=l
TC
Manufacturing
Other
Total Cost
3,800 1,368,800
4,500 1,642,500
115,600,000 1,127,000,000
NOTE: Total cost is rounded to the nearest $100,000.
11-12
-------
TABLE 6. Reference Site Two: Decontamination Costs for Earth
Removal for Areas of 1.0 km2 and 1.0 km2
Cost Element
n
S.
Q
DK
Description
ET X K_P Evacuation
n=1 >
n
M , X K P Population Monitoring
n=l and Decontamination
KULU
u u
n
x
TC
Survey and Samples
Surveillance
Decontamination:
Forest
Shoreline
Residential Area
Temporary Storage
Permanent Disposal
Land Reclamation
Lawn Resodding
Production Losses:
KnPT Other
Total Cost
Costs ($ 1977
1.0
680,700
395,800
15,000
117,900
135,800
348,300
2,600
89,400,000
43,800
414,400
680,700
93,300,000
977)
ToTtT
$ 1,021,100 $ 3,690,900
2,460,600
1,361,300
90,600
2,223,500
2,444,800
1,270,900
31,900
1,084,720,000
825,700
1,512,200
2,460,600
1,103,100',000
NOTE: Total cost is rounded to the nearest $100,000.
11-13.
-------
TABLE 7. Reference Site Three: Decontamination Costs for Earth
Removal for Areas of 1.0 km^ and lO.u war-
Costs ($ 1977)
tost
ET
N
Xl
x3
Element
n
2t/ n
^__ r
n
n'l K"P
S
Q
n
* KnAn
1 ii ii
DKe
FKQ
e
j, VT
u
Jl. ^
r
Si/ ^p
**w* 1
n
Z K PT
nsl
TC
Description
Evacuation
Population Monitoring
and Decontamination
Survey and Samples
Surveillance
Decontamination:
Pasture Land
Field Crops
Orchards
Ditches
Residential Area
Temporary Storage
Permanent Disposal
Land Reclamation
Lawn Resodding
Production Losses:
Agricultural
Other
Total Cost
1.0 kn£
$ 17,600
11,700
164,100
15,000
233,700
126,200
41,300
17,700
6,100
3,500
118,723,200
1,771,500
7,700
47,500
11,700
121,200,000
10.0 km^
$ 54,000
36,000
517,700
90,600
2,337,400
1,290,300
413,000
177,000
18,300
34,900
1,189,616,000
17,841,000
25,500
478,600
36,000
1,213,000,000
NOTE: Total cost is rounded to the nearest $100,000.
11-14
-------
Table. 8 presents the estimated costs if plowing were used on open areas of
reference sites 1 and 3. Plowing was not considered feasible on the other
site since the land areas there wǤre*largely residential, forest, and
shoreline.
Cost estimates for site restriction for the three accident sites are
given in Table 9. The costs of site restriction were based on the
assumption that the land would be condemned, with the least contaminated
----- * •
half decontaminated and then planted with vegetation. The wastes would be
spread on the more highly contaminated half, which would then be covered with
(2\
a biobarrierv ; of rock, earth, and vegetation. Fencing would be erected
and a surveillance system established. This stabilization of the contaminant
would be used until the technology of transuranic recovery or disposal, or
the demand for land, changed to make decontamination of the site both
technologically and economically feasible.
COST ANALYSIS
In developing the cost estimates for the study, it was assumed that
following an accident, the transuranic contamination would lie on the land
surface and be almost totally removed by a single application of the decontam-
ination technique appropriate to that surface area. On open areas, earth re-
moval , plowing, and site restriction were considered mutually exclusive alter-
natives. As a result, a cost gradient related to contamination level is not
apparent in these cost estimates. The cost estimates prepared for WASH-1400^
do show a cost gradient, but that report deals with radionuclides in different
forms and with different characteristics from those of the transuranics con-
sidered in the present study.
A comparison of the pertinent costs of decontaminating and reclaiming
a square kilometer of cropland by dilution (plowing) or removal of the
contaminant,is shown in Table 10. This comparison indicates that, where
the contamination level and land characteristics permitted substitution of
plowing for earth removal, plowing would result in a substantially lower
cost. None of the population-related costs likely to be incurred are
included in this example.
11-15
-------
TABLE 8. Comparative Decontamination Costs ($ 1977) for
Areas Where Plowing is a Feasible Alternative
25-cm Depth
Cost Eleiw
Reference
n
£ K A
n«l
DKC
r
u
>nt Description
Site One
Corn Fields
Plowed Farmland
Hay and Soybeans
Pasture
Woodlots )
Residential Areas > Earth
Industrial Areas J Removal
Temporary Storage
Land Reclamation
I awn Rpsoddino
1.0 km*
$ 87,700
81 ,800
28,000
36,000
50,500
1,800
44,900
300
1,627,900
r 10.0 km*
$ 856,600
817,500
280,200
196,200
168,500
855,400
269,100
3.900
15,217,700
1,020,400
1.0 km*
$ 74.200
45.100
24.000
19.900
50.500
1.800
44.900
300
205,200
..
10.0 taf
$ 741 .900
451 .300
239.900
108.300
168.500
855,400
269.100
3.900
1.790.400
1.020.400
X. : K T Agricultural Production Loss
FK '*
e
TC
Reference
Jl KA
DKe
1 KrLr
Final Disposal
Total- Decontamination-Related Cost
Site Three
Pasture Land
Field Crops
Orchards
Ditches
Residential Areas
Temporary Storage
Land Reclamation
\ Earth
) Removal
45,600
10,728,000
12,700,000
189,700
66,800
41 ,300
17,700
6,100
500
1,854,000
403, 2UU
131,120,000
151,200,000
1,896,600
683,100
413,000
177,000
118,300
3,600
18,675,600
•
10,728,000
11,200,000
104,700
: 57.200
41.300
17,700
6,100
500
354,200
cui ,ouu
131,120.000
137,000.000
' 1,046,900
584.900
413,000
177,000
118.300
3,600
3,557,000
'u u
TC
Lawn Resodding 7,700 25,500
Agricultural Production Loss 47,500 478,600
Final Disposal 18,714,400 121,584,000
Total Decontamination-Related Cost 20,900,000 144,100,000
7,700
23.800
18.714,400
19,300.000
25,500
232.800
121,584,000
127.700.000
NOTE: Total cost is rounded to the nearest $100,000. Population-related costs are not Included since they do
not depend on the decontamination method chosen.
XI-16
-------
;n,i,j (
TABLE 9. Site Restriction Costs ($1977) for Reference
Site Areas of 1.0 km* and 10.0 km*
Cost
Element
ETKtP
MKtP
S
Q
RKtP
ZKt
YKt
VKt
TC
Description
Evacuation
Population Monitoring
and Decontamination
Survey and Samples
Surveillance
Population Relocation
Real Estate Value:
Agricultural
Residential
Commercial
Stabilization and
Restriction
Present Value , «
of Surveillance13'
Total Cost
Reference
.0 km2
$ 6,800
4,500
161,500
t; 15,000
52,500
140,600
200,000
75,000
94,298,000
. 250,000
95,200,000
Site One
10.0 km2
$ 2,463,800
1,642,500
1 ,069,200
:>. 90,600
19, 162', 500 ;
1,243,200
69,160,000
27,375,000
938,731,000
1,510,000
1,062,400,000
Reference
1.0 km*
$ 1,021,100
680,700
395,800
15,000,,
7,94f,50qj!
63,600
28,158,000
—
95,015,000
250,000
133,500,000
Site Two
10.0 km*
$ 3,690,000
2,460,600
1,361,300
90,600
" 28 * 7Q7i*QQO ''"
1,172,200
102,752,000
_.
938,908,000
1,510,000
1,080,700,000
Reference
1.0 km* .
$ 17,600
11,700
164,100
-"• -.; 15*000
•';.. 136-|500
vmzixm^.aK,.-' ,:
146,500
494,000
94,191,000
250,000
95,400,000
Site Three
10.0 km?
$ 54,000
36,000
517,700
90,600
420,000
1,475,600
1,482,000
937,082,000
1,510,000
942,700,000
(a) 100-year period.
NOTE: Total cost is rounded to the nearest $100,000.
-------
TABLE 10. Cost Comparison for Removal and Dilution Techniques
for Transuranic Contamination of 1 km^ of Cropland
($ 1977)
Earth Removal
Plowing
Activity
Soil Stabilization
Decontamination
Temporary Storage
Final Disposal
Reclamation
Production Loss
Total
. (Grader)
$ 177,000
226,000
3,500
(a)
119,200,000^ '
1,806,000
48,000
1-m Depth
$ 177,000
34,500
—
---
1,871,000
48,000
25-cm Depth
$177,000
3,500
. —
~— »
208,500
24,000
$121,460,500V ; $2,130,500 $413,000
If ultimate disposal of the contaminated were in a commercial
repository instead of a Federal repository, the estimated cost
for that factor would be $14,700,000, and the total cost for
the soil removal treatment as defined in this table would be
$16,960,500.(8,9)
In agricultural and nonurban areas in general, the cost of final
disposal of the earth removed accounted for approximately 98% of the total
estimated cost per km2, shown in Table 10. In residential areas final
disposal accounted for 92% of the total estimated cost. If commercial instead
of Federal repositories were used,'these numbers would.be 85% and 50%,
respectively. The effect of final disposal cost on total costs indicates
that examination of alternative means of dose reduction (e.g., dilution and/
or site restriction) would be warranted in a real accident. If the commercial
repositories are assumed, then population evacuation and monitoring costs
and production losses become the largest items for the residential and
commercial areas.
Cost comparisons of alternative means of complying with the Guidance
for contaminated areas are given in Table 11 for the 1 km2 areas and Table 12
for the 10 km2 areas. Although comparative costs are presented for plowing,
site restriction, and earth removal, it does not necessarily follow that
11-18
-------
TABLE 11. Cost Summary for Reference Sites 1.0 km2 In Area
,„„,,.- iv^;, -^i Fflpth --' -
Cost Categories *^Removal
-Reference Site One-
Evacuation and Monitoring
Samples and Surveillance
Decontamination
Temporary and Final Disposal
Land Reclamation
Production Losses
Real Estate Purchase
Population Relocation
Site Stabilization
Total
-Reference Site Two-
Evacuation and Monitoring
Samples and Surveillance
Decontamination
Temporary and Final Disposal
Land Reclamation ,
Production Losses
Real Estate Purchase
Population Relocation
Site Stabilization
Total
-Reference Site Three-
Evacuation and Monitoring
Samples and Surveillance
Decontamination
Temporary and Final Disposal
Land .Reclamation
Production Losses .
Real Estate Purchase
Population Relocation
Site Stabilization
Total
$ 11,300
176,500
451,700
113,243,300
1,616,500
53,900
—
MM-
— — ""
115,600,000
$ 1,701,800
410,800
602,000
89,402,600
.458,200
680,700
MM
MM
M.
93,300,000
$ 29,300
179,100
425,000
118,726,700
1,779,200
59,200
— « ,.
MM
M«
121,200,000
Plowing,
1 m(a7
$ 11,300
176,500
328,700
10,728,300
1,627,900
,53.900
MM
M^
' " MM
12,900,000
$
__
,
-_
__
__
-"."
^^ t
^M
—
$ 29,300
179,100
321 ,600
18,714,900
1,861,700
59,200
^ ^
—
..
21,200,000'j
Plowing.
25 cmU)
11,300
176,500
260,400
10,728,300
205,200
31,100
^•m
11,400,000
$
MM
-' " - - MM
MM
_„
• V
...
$ 29,300
179,100
227,000
18,714,900
361,900
35,500
19,500,000
(a) Earth removal is assumed to be used in areas not suited to plowing
(b) Site restriction costs are based on construction of a biobarrier
(c) Site restriction surveillance is for a 100-yr period.
NOT? * Trtf*a 1 f*f\c+ T ff M«wiM.«4«k«4 4. A £.!._ _L rf>* MA f*A
Site ,M
Restriction^
11,300
415,600
52,500
94,298,000
95,200,000
$ 1,701,800
660,800^
28,221,600
7,941,500
95,015,000
133,500,000
5 29,300
640,500
136*500
94,191,000
95,400,000
11-19
-------
2
TABLE 12. Cost Summary for Reference Sites 10.0 km in Area
Cost Categories
-Reference Site One-
Evacuation and Monitoring
Samples and Surveillance
Decontamination
Temporary and Final Disposal
Land Reclamation
Production Losses
Real Estate Purchase
Population Relocation
Site Stabilization
Total
-Reference Site Two-
Evacuation and Monitoring
Samples and Surveillance
Decontamination
Temporary and Final Disposal
Land Reclamation
Production Losses
Real Estate Purchase
Population Relocation
Site Stabilization
Total
Earth
Removal
$ 4,106,300
1,159,800
4,636,500
1,096,672,200
17,060,300
3,414,500
—
«
—
1,127,000,000
$ 6,151,500
1 ,451 ,900
5,939,200
1,084,751,900
2,337,900
2,460,600
—
~
—
1,103,100,000
Plowing,
1 m(a)
$ 4,106,300
1,159,800
3,443,500
131,123,900
16,238,100
3,414,500
.
—
—
159,500,000
$ --
—
'
~
—
—
' —
.
—
Plowing.
25 cm(a'
$ 4,106,300
1,159,800
2,834,400
131,123,900
2,810,800
3,212,900
—
«
~
145,200,000
$ • , ~ ' '
—
—
'
— >
' . —
—
—
— .
.
Site ,.)
• i n I
Restrict! on l '
$ 4,106,300
( f* \
2,669,800^'
--
—
•
97,778,200
19,162,500
'938,731,000
,1,062,400,000-
$.. ,6,151,500
2,961,900^
-—
-- •,
— -
103,924,200
28,707,000
938,908,000
1,080,700,000
-Reference Site Three-
Evacuation and Monitoring
Samples and Surveillance
Decontamination
Temporary and Final Disposal
Land Reclamation
Production Losses
Real Estate Purchase
Population Relocation
Site Stabilization
Total
1
1
4
,,189
17
,213
90
608
,236
,650
,866
514
-
_
v
,000
,000
,300
,000
,900
,500
,600
-
_
_
,000
$
3
121
18
144
90,
608,
,288,
,587,
,701,
514,
-
—
—
,800,
000
300
000
600
100
600
000
s
2
121
3
128
90
608
,340
,587
,582
268
,
-
-
,500
,000
,300
,100
,600
,500
,800
-
-
-
,000
$ 90
2,118
"
-
-
-
2,957
420
937,082
942,700
,000
--
-
-
-
,600
,000
,000"
,000
Earth removal is assumed to be used in areas not suited to plowing.
Site restriction costs are based on construction of a biobarrier.
v. Site restriction surveillance is for a 100-yr period.
NOTE: Total cost is rounded to the nearest $100,000.
11-20
-------
the least-cost method would be selected for application in a real situation.
Responsible officials would make their choice after considering not only cost
but also such factors as health risks, economic disruption, and ecological
••>*_>.• >-..""!*£.-!•:-?'_•'" ••*:•&'
impacts. For instance, plowing would be less costly than earth removal, but
equipment for 1-m plowing would probably not be readily available, and where
clay or loose rock underlay the topsoil, land reclamation problems caused
by plowing might be very costly. Plowing to a depth of 25 cm would be the
least costly technique for use on open areas, but it might be less effective
1n reducing dose rates than would earth removal or 1-m plowing.
Site restriction without removal of the contamination., would only buy
time, shifting much of the cost into the future. As.estimated in this report,
the costs of site restriction techniques->-excluding costs for population
evacuation, monitoring, and relocation; site purchase (necessary to eliminate
the economic burden on owners of affected land); and fencing—would range
2 2
from about $415,000/km to $9,000,0007km . The low estimate would.be for
Initial sampling and surveillance, use ofI a short-term stabilizer, and,
revegetation. This treatment would be comparable to the minimum treatment
estimate of $500/acre {$123,5007km ) noted in the Guidance. The higher
estimate would be for use of a biobarrier.
o
Table 13 presents a comparison of estimated cumulative costs/km for
all sites and treatments discussed in this report. Differences in the costs
2 2
per unit area between the 1 km and 10 km areas are largely accounted for by
population evacuation and monitoring factors. In real instances, one would
expect greater differences due to scale economy effects. As noted earlier,
the use of unit costs in this analysis precluded the demonstration of such
effects.
Table 14 shows a comparison of unit costs developed in the DOE analysis
and those estimated by EPA. The comparisons shown in the table are somewhat
contrived since the definitions of the items and the assumptions used by EPA
and DOE are, in many cases, quite different. (See Table 1 and Appendices
B, C, and D for details of many of the DOE definitions and assumptions^)
11-21
-------
TABLE 13. Comparison of Estimated Cumulative Costs per
Unit Area for'All Sites and Treatments
Area
1.0 km':
Reference Site One
Reference Site Two
Reference Site Three
Treatment
ER
SR
DP
SP
ER
SR
ER
SR
DP
SP
(a).
Total Cost
($ Million 1977)
115.6
95.2
12.9
11.4
93.3
133.5
121
95
21
,2
,4
,2
Cost/km
($ Hill ion 1977)
115.6
95.2
12.9
11.4
93.
133.
19.5
121.2
95.4
21.2
19.5
Cost/acre
($ Thousand 1977)
468
385
52
46
378
540
490
386
86
79
ro
10.0 knT:
Reference Site One
Reference Site Two
Reference Site Three
ER
SR
DP
SP
ER
SR
ER
SR
DP
SP
1127=0
1062.
159,
145,
1103.1
1080.7
1213.0
942.7
144.8
128.5
112.7
106.2
16.0
14.5
110.3
108.1
121.
94,
14,
12.9
456
430
65
59
446
437
491
382
59
52
(a)ER = Earth removal to depth of 5 cm; DP = Deep (1-m) plowing; SP = Shallow (25-cm) plowing;
SR = Site restriction, including construction of a biobarrier.
-------
TABLE 14. Comparison of DOE and EPA Unit Costs for Area Decontamination and Management
I
ro
CO
th\
t Plus Burden10'
73,500/km2
103.500/km2
20.000/km2
4.000/kiu2
226,000/km2
412,500/km2
710.500/km2
226.000/kin2
282,000/km2
40,000/km2
. 50,000/kra2
Low Cost
$ 49,400/km2
128,400/km2
37.000/km2
8,600/km2
High Cost
$ 296,000/km2
163,00b/km2
405,100/km2
185,200/km2
Assumed
Unit Cost
$ 172.900/km2
148,200/kin2
148,200/km2
123,500/km2
350/home
...
1.275.500/km2
l,597,SOO/ki»2
208.500/km2
65,000/kra2
•t
3,500/knf
3.500/kn2
ISOioOO/kn2
6,000/kn
897.000/kn2
119.200,000/kn2
17.742.COO/ki82
47.000/kn
101,300/km2
352.000/km2
137.000/km2
54.300/km2
4.900/km2
••"$:*•' A
7,400/knf
.
30.000/yr
123,500.000/kn2
600/k«
9 '-
469,300/taT
774,300/km2
209.900/km2
175.400/km2
16.100/kin2
163,000/km2
57.000/yr
185.250.000/km2
3.400/ta
y
259,400/km
563,200/km2
, 179.100/km2
88.900/lp2
11.100/fai2
49,400/{m2
No estimate;
164,255.000/kn2
2.300/kn
IOO.OOO/kJc)
tPA uetlnuidns
and Assumptions
Short-term stabilization.
Long-term stabilization.
Ho estimate.
No estimate.
Scraping into mounds.
No estimate.
No estimate.
No estimate.
No estimate.
Ho estimate.
No estimate.
Seeding, not sod. .
Probably assumes open areas.
Assumes soil nucded on 95Z
of area.
Long-term stabilizer plus
mulch. ;,
Includes application. ?
No estimate.
"Shallow" plowing.
"Deep" plowing.
Guard service, no area
basis.
No estimate.
No estimate.
Computed equivalent
based on EPA cost/10 acres.
Ho estimate. " *
Two Weeks of Hater Fixation $
Long Acting Stabilizer
Corn Removal
Other Crop Removal
Earth Removal (Grader)
Earth Removal (Front End Loader)
Earth Removal (Manual Labor)
Field Sod Removal
lawn Sod Removal
Vacuum!zed 'Sweeper for Streets
Fire Hosing
Homes
Population Monitoring & Decontamination
Evacuation, Including Room, Board.
Transportation and Personnel??! P- 12-3)
Lawn Resodding
Topsoil Replacement
Erosion Control
Fertilizer + Seed (Materials Only)
Temporary Storage Sites (Except Land Cost)
Plowing
25 cm
1 m. Tilled Land . .
I », Pasture. Including Deseeding11' p> lz'"'
Surveillance (Based on Periseter Length)
Conercial Areas
Disposal (1000 Miles of Transportation.
2* Soil Rtwoval)
Biobarrier (labor and Materials)
Fence (Based on Perineter Length)
Present Value of Future Surveillance
* T,I- '— EPA Cutdance SuwaryJlMort.0"Table VI-?. "OecontMilnation Costs." EPA qiven in $/acre converted to $/ta2 for
The EPA document includes cost estimates for sows treatment Measures not used in DOE esttnates.
Include overhead (251). loss of efficiency due to protective clothing (304), workmen's co^>ensat1on and social
»J. except for land reclamation costs which do not require protective clothing and include only overhead and
security. All unit costs are rounded to the nearest $500. jr . «no
'Cott (estimate dues not «SSUK any burden.
-------
Nevertheless, the table is a helpful point of departure for a discussion of
the reasons for the differences between the cost estimates of DOE and EPA.
The estimates differ by a factor of about 3 or less, except fpr lawn resodding
(where the EPA estimate is for seeding while the DOE estimate is based on
application of sod) and fencing (where the basis for the EPA estimate 1s not
specified'and DOE assumes use of a high chain-link fence). The differences
noted in Table 14 do not account for the more substantial differences between
the EPA and,the DOE estimates of overall treatment costs per unit of area.
In the Guidance Summary Report, (n> section 2, p. 17) n is noted that
"A minimum cost of $500 per acre [$123,500/km2] has been assumed for estimating
the costs which may be incurred in bringing all areas above the designated
level into compliance." This figure is nearly two orders of magnitude smaller
than the minimum DOE'estimated costs/km2 indicated in Table 13. The major
differences between the DOE estimated costs/km2 and the EPA's $500/acre
minimum estimate are the treatment assumed and the associated activities
considered. The EPA minimum estimate includes only initial radiological
surveillance, application of a short-term soil stabilizer, and revegetation
with grass, although the EPA presents unit cost estimates for.a broad range
of other treatment alternatives (11» Table VI-2). The DOE estimates, as
discussed in the preceding pages, include as essential actions: evacuation
and monitoring of the human population from the affected site, radiological
samples and site surveillance, site decontamination, temporary and final
disposal of any contaminated soils and vegetation removed from the site,
land reclamation, production losses due to interruption of economic activities,
and—where decontamination is not feasible—site stabilization, real estate
acquisition, and permanent relocation of population.
11-24
-------
REFERENCES
i • .
1. U.S. Nuclear Regulatory Commission, Calculation of Reactor Accident
Consequences. Appendix VI to Reactor Safety Study.U.S; Government
Printing Office, pp. 12-3 through 12-12, October 1975.
2. J. F. £line, G. M. Holter, W. H. Rickard and E. L. Klepper, Experimental
Design for Demonstration of Bio-Barriers Placed in a Simulated BuriaT
Trench.BNWL-2035, Battelle, Pacific Northwest Laboratories, Richland, WA
99335, May 1976.
3. United States Department of Agriculture, Agricultural Statistics 1976.
U.S. Government Printing Office, Washingtoni DC, 1976.
4. Raymond W. Goldsmith, ed.. Institutional Investors and Corporate
Stock—A Background Study. National Bureau of Economic Research,,
Columbia Uni versity Press, New York, 1973.
5. United States Department of Commercea 1974 Gensus_ of Agriculture.
U.S. Government Printing Office, Washington, DC,.1977.~~
6. United States Department of Commerce, County and City Data Book 1972.
U.S. Government Printing Office, Washington, DC, 1973.
7. United States Department of Commerce, 1970 Census of Population; Detailed
Character!stics, United States Summary. U.S. Government Printing Office,
Washington, DC, 1971.~~
8. J. R. Young, Procedures for Estimating Nuclear Fuel Cycle Costs.
"~~!i, Ri
99,352, 1977.
BNWL-2210, Battelle, Pacific Northwest Laboratories, Richland, WA'1
9. Tri-State Motor Transit Company, Freight Tariff Number 1070-A.
Docket MC 109397, p. 5, effective July 26, 1977.
10. Final Generic Environmental Statement on Use of Recycle Plutonium in
Mixed Oxide Fuel in Light Water Copied Reactors.8 U.S. Nuclear"
Regulatory Commission, Vol. 4, p. XI-29, August 1976.
11. United States Environmental Protection Agency, Proposed Guidance on
Dose Limits for Persons Exposed to Transuranium Elements in the General
Environment: Summary Report. Washington, DC, September 1977.
11-25
-------
-------
APPENDIX A
SITE DESCRIPTIONS
-------
-------
APPENDIX A
SITE DESCRIPTIONS
Since the analysis of impacts is presented specifically for each refer-
ence site, the site-specific variables are given here as simply and as
explicitly as possible. A modified outline format allows easy identification
of the reference sites and quick comparisons of factors across sites.
The site descriptions included in this section served as the basis for the
development of site-specific decontamination plans (Appendix C) and impact
analyses (Section II and Appendix E). The sites were selected 1) to include
the land types deemed importants 2) to occur in different important biomes,
and 3) to be we!1-documented.
Each site description that follows includes all information needed to
identify detailed decontamination steps to be used as a basis for .analysis
of the site. Specifically mentioned are characteristics.which affected the
selection of alternative decontamination techniques and the rate at which
the decontamination effort might be expected to be accomplished. Analyses
were conducted for each site on the alternative assumptions that 1-km and
10-km areas were found, after the hypothetical contaminating events, to
require remedial treatment.
REFERENCE SITE ONE
Topography: The area is a floodplain. Ravines are the principal feature to
the west and east of the floodplain. The elevation is approximately
1000 ft (300 m) above sea.level. A major river flows next to the acci-
dent site.
Climate: Rapidly changing weather; the area is located midway between two
distinctive climatic zones (humid-east and dry-west). The average
temperature is 53°F (12°C).
Rainfall: Average annual rainfall: 30 in. (76 cm).
A-l
-------
Vegetation: Native grasses and shrubs, with ash, elm, .and cottonwood trees
along bluffs.
Land Use; Within a 10-mile (16-km) radius of the accident site, 70% of the
land area was assumed to be in farms. A breakdown of the area into land
types follows:
Corn Fields - 37%
Hay and Soybeans - 14%
Idle Farmland - 25%
Pasture Land - 7%
Forest - 3%
Population Areas - 14%
Population Distribution in Cleanup Areas:
2 •
Area (km ) Population
1.0 15
10.0 5475
Description of Contaminated Area:
• Depth Profile - All plutonium was assumed to be located on or near the
surface, since a fresh deposition was being considered.
• Isotopic Mixture - (wt%)
238r
239
240
241
242
241
JPu - 1.4%
Pu - 58.0%
Pu - 24.0%
Pu - 9.0%
Pu - 4.9%
Am - 2.4%
A-2
-------
• Areas to be Decontaminated -
Land Type
Corn Fields
Idle Farmland
Hay and Soybeans
Pasture Land
Residential Area
Commercial Area
Forest
o
Area (knr)
1.0
0.37
0.25
0.13
0.11
5 Homes
0.05
0.09
10.0
3.70
2.50
1.30
0.60
1.40
0.20
0.30
REFERENCE SITE THO
Topography: Moderate variation in elevation, with ground elevation 0-40 ft
(0-12 m) above sea level.
Climate; The mean daily maximum and minimum air temperatures during the
warmest month are 83°F and 64°FX51°C and 18°C), respectively. Daily
minimum temperatures for the coldest months average about 22°F (-5.5°C).
Rainfall and Humidity; Average annual rainfall: 45 in. (114 cm). Average
relative humidity: 75%.
Soils; Glacial Soils - sand and gravel (till and outwash).
Ground Water; There is no danger that surface drainage from the accident
site could affect public reservoirs, because of the low permeability of
soils in the area and a ground water gradient sloping from the reservoir
to the site.
Vegetation and Wildlife; The area comprises mainly secondary-growth hardwood
forests. Hardwoods include beech, sugar maple, and birch* with hemlock
also abundant. Wildlife includes woodchucks, skunks, racoon, grey
squirrels, and cottontail rabbits. A wide variety of upland birds and
sea birds Is present in the vicinity of the accident site.
A-3
-------
Population Distribution 1n Cleanup Areas:
Area (km ) Population
1.0 2269
10.0 8202
Description of Contaminated Area:
• Depth Profile - Contamination was assumed to be located on or near the
surface, since a fresh deposition was being considered.
• Isotopic Mixture - (wt%)
238,
239
240
241
242
'Pu - 1.4%
Pu - 58.0%
Pu - 24.0%
Pu - 9.0%
Pu - 4.9%
241Am - 2.4%
Areas to be Decontaminated -
Land Type
Forest
Shoreline
Population
Area (km )
1.0 10.0
0.21 3.96
0.22 3.96
0.57 2.08
REFERENCE SITE THREE
Location and Topography; Located between two mountain ranges. The terrain
around the accident site is f 1 at-to-ligilt-rolling at an elevation of
130-280 ft (40-85 m) above sea level. Rainy winters are typical, with
fair summer, spring, and fall seasons.
Climate; Temperatures are greater than 90°F (32°C) on 80 days/yr, and less
than 32°F (0°C) on 32 days/yr.
A-4
-------
Rainfall and Humidity; Average annual precipitation: 16 in. (41 cm).
Humidity is greatest in the winter (88% average), compared with 48% in
the summer. _
Soils; Hard-to-very-hard-silts, and silty clays with dense-to-very-dense
sands and gravels.
Surface and Ground Water; The area is bounded by well-defined drainage
courses and natural gullies that intercept surface runoff .from the
higher surrounding terrain. Unconfined or semiconfined ground-water
conditions occur in this area; ground-water levels are about 157 ft
(48 m) below the ground surface.
Vegetation and Wildlife; Vegetation is predominately bunchgrasses and
various other grasses. Mammals in the area include ground squirrels,
jackrabbits, coyotes, badger and skunk.
Land Use; In a 5-mile (8-km) radius from the accident site, land is
exclusively agricultural. Grazing land dominates, with some field
crops and orchards. No dairy cattle are located within the 5-mile
radi us.
Population Distribution in Cleanup Areas;
..'2
Area (km )
7 1.0
10.0
Population
39
120
Description of Contaminated Area;
• Depth Profile - All plutonium was assumed to be located on or near the
surface, since a fresh deposition was being considered.
* Isotopic Mixture'- (wt%)
238n..
239
240
241
242
241
Pu-
'Pu-
Pu -
Pu -
'Am-
58.0%
24.0%
9.0%
4.9%
2.4%
A-5
-------
• Areas to be Decontaminated -
Land Type
Pasture Land
Field Crops
Orchards
Irrigation Ditches
Residential Area
Area (km2)
1.0 10.0
0.58 5.80
0.31 3.17
0.07 0.70
0.03 0.30
0.01 0.03
A-6
-------
APPENDIX B
SAMPLING
-------
-------
APPENDIX B
SAMPLING
The sampling scheme presented in this section was developed solely to
provide a basis for estimating costs in the analysis of the three hypotheti-
cal^ contaminated reference sites discussed in this, report. While the scheme
was designed to be consistent with the requirements of the Guidance, it should
not be considered in any way a guide for actual sampling programs for real inci
dents. Sampling programs for use in such cases would have to be designed for
the specific circumstances of those incidents, including such variables as
site location, land types, involved meteorological conditions, and precipita-
tion. Following the Guidance, it was concluded that the sampling scheme would
need to:
• Define those land areas in which the contamination exceeded.the soil
o
screening level (0.2 u Ci/m ).
« Provide a basis for determining those areas in which dose rates to
human occupants would be expected to exceed 1 mrad/yr to the pulmonary
1ung or 3 mrad/yr to the bone.
• Provide a basis for choices among possible remedial treatment methods.
• Assess the extent of residual contamination following remedial treat-
ment of the affected areas.
Three factors were considered in costing: 1) labor needed to collect
the samples, 2) laboratory analysis of the samples, and 3) power supply for
the air samplers. Equipment needed for sampling (e.g., portable alpha meters,
FIDLERs, Ge(Li) vans, and air samplers) was assumed to be available at nominal
or no cost. A labor cost of $2.50/sample or survey reading was used, based
on the assumption that it would take two monitors 10 min to obtain one sample.
This cost may seem high, but it allowed for time to move to the next sampling
location. Analysis of all samples (soil, air, vegetation, foodstuff, urine,
and animal feces) was assumed to cost $100/sample. These analyses would give
B-l
-------
the isotopic breakdown necessary for dose calculations. Several particle-size
fractionatiori studies of air samples were also assumed to be necessary for dose
calculations. Power lines were assumed installed for the operation of air sam-
plers in the affected areas at costs of $3/ft ($10/m) for lines installed above
ground and $10/ft ($33/m) for underground installation.
For most aspects of the sampling program, it was assumed that the number
of samples required, and therefore the cost, was sensitive to the size of the
affected areas but not to other differences in the areas. While this is con-
trary to expectations for real incidents, as noted above, it was considered an
appropriate simplification for the kind of analysis reported here. Two excep-
tions to this simplification were made. Numbers of samples, and costs, for
monitoring of the human population and for analyzing possible contamination of
foodstuffs were estimated specifically for each site and for the ultimate
2 2
assumptions that 1 km and 10 km required remedial treatment. A summary of
the assumed sampling requirements is presented in Table B.I.
The proposed EPA Guidance states (page 14 of Annex V) that "acceptance
criteria which allow a maximum chance of error of 5-10% are generally con-
sidered appropriate." It is assumed that this statement refers to the two
types of decision errors that could be made: first, deciding that remedial
action is required when that is actually not the case; and second, deciding
not to take remedial action when such action should be taken according to the
guideline. By specifying acceptable probabilities for these two errors, it is
possible in a real situation to estimate the number of samples that should be
taken to detect a contamination level greater than the Guidance value. The
approximate numbers of samples given in Table B.I, however, were not derived
on the basis of any specification of the two decision errors because the
Guidance gives no indication of the statistical test criteria for determining
whether or not Guidance limits have been exceeded. Different test criteria
would result in different requirements for numbers of samples.
B-2
-------
TABLE B.I. Approximate Sampling Requirements for. Delineating Areas Needing
Remedial Treatment and Assessing Treatment.Adequacy(a)
Definition af Areas Exceeding
Soil Screening Level(o> ~
1. Instrument Ground Surveys
along Radii
• FIOLER
• ALPHA
• Ge (Li)
2. Soil Samples along Radii
3. Profiles for Depth Characterization
4. Soil and Instrument within
Sampling Units
• Ge (Li)
• Soil
Dose Estimation
5. Soil and Instrument Surveys
• Ge (Li)
e Soil
6. Air Samples(d)-
7. Vegetation
8. Foodstuffs
" • Site 1
• Site 2
• Site 3
9. Population (Human) Monitoring
• Site 1
• Site 2
• Site 3
10. Water and Sediments
11. Wildlife and Domestic Animals
Post Cleanup Sampling
12, Soil and Instrument
• Ge (Li)
• Soil
13. Air Samples
14. Vegetation
15. Foodstuffs
• Site 1
• Site 2
. • Site 3 .
16. Water and Sediments
17. Wildlife and Domestic Animals
18. Population (Human) Monitoring
• Site 1
• Site 2
• Site 3
.Hypothetical Cleanup Area
1 kaf- : 10 km
-------
DEFINITION OF AREA CONTAMINATED BEYOND THE SOIL SCREENING LEVEL
Meteorological conditions at the time of any real contaminating incident
would be considered in planning the initial ground surveys. For purposes of
this analysis, it was assumed that the ground was surveyed on radials running
out from the accident site at 15° intervals (Figure B.I) as necessary to define
2
the boundaries of the area contaminated beyond 0.2ii Ci/m . One Ge(Li) scan
was assumed for each 10 portable instrument readings, the total numbers of each
test approximating those shown in Table B.I.
In the assumed sampling program, FIDLER and Ge(Li) detector readings were
taken in the field as a check on the validity of'alpha readings rsince :the
FIDLER and Ge(Li) techniques are sensitive to the 60-keV x-rays from Am,
rather than the plutonium alphas. Soil particle-size fraction studies were
assumed on several soil samples to estimate the distribution of contamination
in the various soil-size fractions. This information would be necessary for
dose calculations.
FIGURE B.I.
Pattern of Radials for Sampling for a
Hypothetical Contaminating Event
B-4
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Soil profiles were assumed taken at various distances frbnv the accident
site and for various land types encountered. The depths to which such profiles
would be required in a real incident would depend upon.,the, length of "time.,.,,"
between the accident and the takingrof samples and upon sthe nature of .any dis-
turbance, which .might have occurred during this period.
2
The final assumed step in determining the<0.2u Ci/m> boundary involved
dividing the: land area into sampling units at the approximate boundary. Within
these units additional soil and Ge(Li) readings were assumed to be taken. Sta-
tistical analysis/of these data was.assumed to involve,such parameters as the
• ..•.;•, •..---.. , ,-.-.. - , - . . - A
arithmetic mean, median,..proportion of observations above p.2u Ci/m , largest
concentration obtained, and spatial orientation of the samples.
DOSE ESTIMATION \ .,- ,;. ^; ; , , , s.
The next steps in the assumed sampling were the division of the area' con-
p
taining levels greater than 0.2u Ci/m into activity strata and the collection
within these strata of samples of water, sediment, foodstuffs, vegetation, air,
small mammals, and additional soil. The number of samples and portable survey
readings assumed needed in this phase are presented in Table B.I.
Since inhalation may be the primary pathway for the introduction of
Plutonium into the body, air monitoring was assumed necessary, especially
during decontamination.procedures. Several portable air samplers were assumed
to be placed upwind (for.controls) and downwind from the accident site to help
locate any immediate resuspension problems that would need to be considered
.. \ • " •.'•...-.•' .•:''. • '.. .""'•',.,''
before survey teams moved in. Particle-size analysis, was included to
assist in the determination of dose to the lung from,respirable soil particles.
It was assumed that following initial characterizations air samplers were
. - - •.''••- . o
placed every 500 ft (152 m) along the perimeter of the 0.2y Ci/m boundary.
Filters were assumed to be changed every 2 wk for up to 1 yr.
The samplers would provide data on the air concentrations of contaminants
leaving the area due to the resuspension from ground contamination in the
affected area and decontamination operations^ ; ' ,: 1
B-5
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Additional air samplers were positioned withirv the perimeter during
cleanup for the determination of possible occupational risks. Approximately
25 samplers/km2 were assumed necessary for the 10 km2 areas in this analysis;
10 samplers/hectare were assumed needed for the 1 km areas. Additional air
samplers were also considered to be used in the vicinity of temporary contami-
nated soil storage mounds.
The following types of samples were* assumed collected to help to estimate
the dose to man from the ingestion pathv/ay: 1) crops such as wheat, corn,
potatoes, tomatoes, etc; 2) water for humans and farm animals; 3) milk, milk
products; 4) hair and feces of farm animals and pets; and 5) liver and muscle
of cattle, chickens, and other edible farm animals. About 20 samples per farm
i)
within the 0.2y Ci/m boundary were assumed to have been collected. In Table
B.I, the number of samples shown under "foodstuffs" is specific to each site
and assumes 20 samples per farm; the numbers of farms in the affected areas
were estimated by dividing the size of the areas by the average-size farm for
the respective regions of the country.
It was assumed that the population within the areas designated for reme-
dial treatment would undergo a personnel survey. Table B.I shows for each
reference site the estimated number of samples requiring analysis, based on
the population within the affected area. Follow-up sampling was considered
necessary for persons who showed positive results.
Sediments of ponds and rivers in the contaminated areas would be expected
to accumulate radionuclides. Accordingly, water and sediment samplers were
assumed to be collected, as indicated in Table B.I.
POST CLEANUP SAMPLING
Post cleanup monitoring was assumed to be handled by dividing the decon-
taminated area into units and taking Ge(Li) scans and soil samples within each
unit. Included were several soil profiles needed to determine whether soil
had been removed to an adequate depth.
B.-6
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Post cleanup monitoring was also assumed to include samples of air, vege-
tation, foodstuffs, water, sediment, and animals. Sampling of vegetation was
considered to be continued for several years after cleanup to ascertain that
plants were not taking up any transuranic materials that might have escaped
the decontamination processes. As shown in Table B.I, post cleanup monitoring-
of the human population within the affected areas was also assumed.
B-7
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-------
APPENDIX C
REFERENCE DECONTAMINATION PROCEDURES
-------
-------
APPENDIX C
REFERENCE DECONTAMINATION PROCEDURES
The EPA Guidance specifies no procedures for use in stabilizing or
decontaminating areas impacted by releases of transuranics... A variety of
ways could be proposed to bring contaminated areas into conformance with
the Guidance. As a basis for assessing in this analysis the costs and other
impacts of compliance with the Guidance sets of procedures were selected
which were judged to be realistic, workable, approaches to the removal or
stabilization of contaminated soils following an accidental release of tran-
suranics. It is unlikely that the selection of alternative procedures to
achieve the same ends would have produced large differences in costs or other
impacts. However, the procedures described here were assumed for the purposes
of illustratory analysis only. The labor requirements and timing assumptions
for these procedures, used as a basis for cost estimates, are summarized in
Table C.I.
GENERAL APPROACH
Area Restriction, Stabilization, and Evacuation
A series of steps was assumed, solely as a basis for analysis, to be
taken following each hypothetical contaminating event:
• The area of suspected contamination was defined.
• Traffic into and out of this area was restricted.
• Individuals in the area were alerted to take appropriate precautions to
prevent personal exposure.
• Monitoring teams, equipped with portable equipment, were dispatched to
define the area which would probably require remedial treatment.
• People in the probable treatment area were evacuated, examined for
radiological contaminants,,and housed in temporary evacuation centers
C-l
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TABLE C.I Man-Hour Estimates and Removal Deadlines
for Decontamination
Land Area Man-hr/km2
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Cropland (cornfield)
- Corn Removal
- Soil Removal
- Total
Grazing Land
Pavement
Forest
Ditches
Roof Areas
- Sloped
- Flat
Lawns
Homes
Population Area
Orchards
Shoreline
600
2,200
2,800
3,200
500
25,800
8,600
1,300
6,500
11,600
37,500
16,200
8,600
15,600
Cleanup
Deadline
1 month
1 year
1 year
1 month
1 year
1 year
T month
1 month
1 month
1 month
1 month
1 year
1 year
C--2
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(e.g., nearby schools or community centers). They were maintained in
these centers until survey teams concluded that it was safe for them
to return to the area or until more permanent housing was arranged.
• Areas identified as contaminated were treated where appropriate with
water spray and later with a longer-acting stabilizer to control the
spread of the transuranic materials.
Removal of Contaminated Soils
Where removal of soils was assumed to be a part of the remedial treat-
ment procedure, the following steps were included as a cost basis:
• Soil was scraped to a depth of 5 cm.
« Soil was hauled by dump truck to temporary storage sites (about 1 site
for each 2-km contaminated section).
• Soil was bulldozed into temporary mounds for storage, and the mounds
were treated with soil stabilizers to prevent resuspension or erosion.
• Within about 1 yr, the soil in the mounds was packaged in 55-gal (208-&)
drums and shipped in unshielded vans an average of 1000 miles (1600 km)
for ultimate disposal in Federal disposal sites.
These steps were based upon the expectation that the transuranic mate-
rials would be concentrated in, the top few cm of soil in recently contaminated
areas. Fresh depositions would migrate only to a limited depth, according
to research on the subject. Jakubick,(1^ for instance, predicted a migra-
tion rate of only 0.8 cm/yr in soils studied in Germany. Specific cost
bases were taken from BNWL-2210, (2) the Tri-State Motor Transit Company,
and GESMO.(4' *
Plowing of Contaminated Soils
Plowing is a method by which contamination can essentially be buried
in place, eliminating the need for costly final burial. Plowing was con-
sidered here as an alternative decontamination method for cropland and
grazing land.
C-3
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Plowing to depths of 10 in. and 3 ft (25 cm and 0.91.m) was considered
here. Ten-inch plowing was 'assumed to.be done with a 100-hp farm tractor and a
standard 7-bdttom farm plow. One pass with the plow at a rate of approxi-
mately 125,000 m2/day(a) was predicted to yield a residual fraction of 20%.
Assuming one worker per plow, an effort of approximately 8 man-hr/km was
estimated to be required.
Deep plowing to 3 ft M m) can bury approximately 95% of the surface
contamination deeper than 2-3 ft (0.7 m),(6) which would allow uptake of
contamination from only deep-rooted plants. Deep plowing was assumed to be
done by two large crawler tractors pulling a moldboard plow, capable of
36-in.-deep furrows.(6'7) A crew of four was considered to be necessary: two
tractor drivers, one person at the controls of the plow, and one laborer.
About 1 acre (4000 m2) was estimated to be plowed per hourv with an effort
of approximately 4 man-hr per acre or 1000 man-hr/km .
Post-Decontamination Survey
Final release surveys were considered to be necessary for all decon-
taminated areas. Steps included resampling, primarily by soil and air moni-
toring with some portable instrument surveys. Vegetation and foodstuff
sampling was considered to be necessary to assure that uptake by plants
did not present a risk to the public. Estimates of the number of samples
needed for the final release survey are presented in Appendix B.
APPROACHES SPECIFIC TO LAND TYPES
The appropriateness of various decontamination methods would vary with
the types of land or land uses affected. Descriptions of methods assumed
for various land types and uses in this analysis are presented below in an
outline format for easy reference. These descriptions include rate factors
needed to make consistent cost estimates for the decontamination methods
assessed in this report.
S*Jp. Tvergyak, 1978, Extension Economist, Coulee Dam, WA; private communication.
^Approximately 20% of the original surface deposition would remain.within the
top 1 cm and be available for resuspension.
C-4
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For those methods that involve soil removal, estimates of man-hr require-
ments are included. Manpower needs for transport of soil to a temporary stor-
age site are described in Appendix D. For final burial, manpower needs were
taken from BNWL-2210. Labor requirements for monitoring are presented in
Appendix B. Supervisory personnel are accounted for in the discussion of the
25% burden of the unit cost (text Section II).
DECONTAMINATION OUTLINE
I. Cropland
A. Stabilization
A road-type sprayer was assumed used to apply the initial water-
spray stabilizer. After the crop was cut and removed, the soil
was expected to be covered with a long-acting stabilizer. A
'.-••-• 9000-gal-capacity (34,000-£) tanker truck with spray bars and a
five-man crew was estimated to be able to apply the stabilizer at
a rate of
-------
The crop was assumed to be cut and removed in one operation, using
a harvesting-chopping machine. With a three-man crew, <30 tons
(27 tonne) of cropland cover was estimated to be removed per hr.
This rate depended upon a mix of crops being cut since, for example,
corn could be removed at a rate of 1-1.5 acres/hr (4000-6000 m /hr)
while hay could be removed at approximately five times that rate.
The freshly cut crop was considered to be hauled to a temporary
storage site where it was placed in 55-gal (208-5,) drums and
stored until shipped for permanent burial. An effort of
^00 man-hr/km2 was estimated to be required for crop removal.
D. Soil Removal
E.
Where necessary, a large road grader (12-in. or 30-cm blade) was
assumed to be used to remove the soil down to an appropriate
depth. With a three-man crew, the grader could remove soil at a
rate of 4.0 equip-min/103 ft2/5) which is equivalent to an effort
of 2200 man-hr/km2. A front-end loader (5-yd3 or 4-m capacity)
was considered to be used to clean up the windrows left by the
grader.
Plowing
Where plowing is considered in this analysis, it is assumed that
it was accomplished as described under "General Approach," above.
II. Grazing Land
A. Stabilization
The initial water-spray stabilizer was assumed to be applied
within 24 hr of the accident, using tanker trucks with spray bars,
Water was considered to be applied on alternate days until the
long-acting stabilizer was distributed. One-tenth inch (0.25 cm)
of water was estimated to be applied at a time, the soil stabili-
zer was assumed to be applied to affected areas within 1 month.
C-6
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B. Characteri zati on
Refer to IV-B. In additions monitoring of cattle (feces and
tissue analyses, plus milk analysis for dairy cows) was assumed
necessary.
C. Removal
A self-propelled sod machine (20-in. or 51-cm blade) was expected
to be used on the grazing land. When removing soil to a depth of
2 in. (5 cm), approximately 10,000 ft2/hr^ could be removed.
With a three-man crew, ^3200 man-hr/km2 would be necessary to
complete removal. In areas not accessible to the sod machine,
either a front-end loader or manual methods of removal were
assumed used. Deadline for removal was set at 1 yr.
III. Forest Land
A. Stabilization
It was assumed that access to the forest was controlled for
several months after the accident to allow rainfall to wash
contamination into the forest mat.
B. Characterization
Soil and vegetation samples were assumed to be taken periodically
during the isolation phase to determine whether contamination was
being washed into the forest mat. Air monitoring stations were
also posited on the periphery of the forest to identify any resus-
pension problems.
C. Removal
It was assumed that the forest mat was removed where it was
contaminated, leaving most of the trees standing. Half of the mat
was considered to be removed by a small front-end loader (1.5 yd3
or 1.2 m ' capacity) and half by manual methods. A front-end
loader with a two-man crew would require an effort of 8600 man-hr/km2/5^
while manual shoveling with a four-man crew would requ-ire
D. Jenks, 1977, Redeturf, Inc., Aurora, Oregon; private communication.
C-7
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43,000 man-hr/km2/5) Overall, an effort of 25,800 man-hr/km was
estimated to be required. Deadline for cleanup was 1 yr following
the accident.
IV. Populated Area
A. Stabilization
In populated areas, it was anticipated that the initial water-
spray stabilizer was applied within 24 hr of the accident. Applica-
tion was by tanker trucks with spray bars, and occurred on
alternate days until a long-acting stabilizer was spread. A
smaller capacity tanker (2000 gal or 7600 A with one spray nozzle)
was assumed to be used to apply the stabilizer to more confined
areas of the population center. Initial water-spray and long-
acting stabilizers were assumed not to be applied to pavement or
roof areas.
B. Characterization *
Every home in contaminated areas was assumed to require an interior
and exterior survey. The exterior survey involved a check of the
roof and chimney area and spot checks of the walls. Interior
surveys included a survey of entrances, filtering systems, and
easily accessible surfaces (tables, floors, etc.).
If no contamination was found, a complete survey was estimated to
require an average effort of 4 man-hr^a' per three-bedroom home.
If contamination was found during the survey, it was expected that
monitors would need to do a more complete survey requiring approxi-
mately 8 man-hr.^a'
C. Removal
1. Pavement
Rough-textured concrete or asphalt roads were assumed to be
cleaned up using a vacuumized mechanical sweeping machine
J. R. Berry, 1977, Pacific Northwest Laboratory, Richland, WA; private
communication.
C-8
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3.
traveling at a speed of 4 1/2 mph (7.2 km/hr). Two passes
were estimated to be required to get a residual fraction of
less than 10%. A work rate of 2.8 equip-min/103 ft2^
and a one-man crew would yield approximately 500 man-hr/km2.
Removal deadline was set at 1 month, except for evacuation
routes that required immediate cleanup.
2. Roofs
Firehosing (3/16- x 9/16-in. or 0.48- x 1.4-cm orifice;
120 psi or 8.4 kg/cm2; 0.12 gal/ft2 or 4.9 £/m2)^5^ with
three persons per nozzle was the assumed method for removing
particles contaminated with transuranics. Firehosing of
sloped roofs would require 2.4 nozzle-min/10 ft ^ ' or
26 nozzle-min/103 m , *5' or an effort of 1300 man-hr/km2.
Firehosing of flat tar and gravel roofs would require
12 nozzle-min/103 ft2^ or an effort of 6500 man-hr/km2.
For this study, roof areas were assumed to include 50% sloped
roofs and 50% flat tar and gravel roofs; therefore, an effort
of 3900 man-hr/km2 was estimated.
Roofs were assumed,to be decontaminated prior to lawn and
home exterior cleanup so that contamination displaced from
the roof would be removed in later decontamination-phases.
Some roof runoff might run into storm sewers and from there
go either to a sewage treatment plant or a nearby stream or
river. For this reason, sludge was assumed to be monitored
at sewage treatment plants and packed into 55-gal (208-&)
drums for burial if determined to be a risk. Runoff into
streams and rivers was considered to be checked by monitoring
stations along these waterways. Removal deadline was 1 month.
Lawns .
Lawns were assumed decontaminated using sod machines; areas
not accessible to the self-propelled machine used for the
grazing land (refer to II-C) required use of a smaller machine
C-9
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with a 12-in. (0.3-m) blade and a two-man crew. The average
effort required for lawn removal was estimated to be
2 (9}
11,600 man-hr/km .v ' Removal deadline was 1 month.
4. Home Decontamination
In a 1-km area, homes were considered to take up 23% of the
land area (2.5 x 106 ft2 or 2.3 x 105 m ). An average home
was assumed to occupy ^2.00 x 103 ft or 190 m ; therefore,
2
about 1250 homes would occupy 1 km . At a cleanup rate of
30 man-hr/home,'a' an effort of 37,500 man-hr/km was estimated
to be required for home decontamination. Each decontamination
crew consisted of four persons. Removal deadline was set at
1 month.
D. Overall Cleanup Rate
The composition of a populated area was assumed to be the follow-
ing, based on assumptions in WASH-1400:^°'
1) Lawn, fields - 57%
2) Pavement - 20%
3) Roof - 23%
4) Home and other buildings - 23%
To obtain an estimate of overall effort for the decontamination of
a populated area, the above percentages were multiplied by their
p
corresponding man-hr/km values and summed, yielding an assumed
2
effort of 16,200 man-hr/km .
V. Shoreline
A. Stabilization
It was assumed that an initial water-spray stabilizer was applied
within 24 hr of the accident, using tanker trucks with spray bars
wherever possible. Water was considered to be applied on alternate
days until the long-acting stabilizer was distributed. The
U)
J. R. Berry, 1977, Pacific Northwest Laboratory, Rich!and, WA; private
communication.
C-10
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. stabilizer was assumed to be spread directly on the shoreline, and
all affected-areas were-considered to be treated within 1 month.
B. Characteri zati on
In addition to preliminary monitoring to determine the extent of
the affected area (the area above the guideline limit), soil core
samples were assumed to be taken,to indicate the depth of soil to
be removed where percolation or -soil movement/was suspected.
Air monitoring stations located on fringe areas were posited to
identify possible resuspension problems particularly during the
'cleanup phase.
C. Removal
Since the composition (clay, soils, sand, and gravel) and acces-
sibility of a shoreline are highly variable, several methods were
considered to be used in cleanup. The following distribution of
methods was assumed for this analysis:
1) Road grader (see I-C) - 25% of shoreline
2) Manual (see III-C) - 25% of shoreline
3) Small front-end loader (see III-C) - 50% of 'shoreline.
To obtain an estimate of overall effort, the above percentages
2
were multiplied by their corresponding man-hr/km values and
2
summed, yielding an estimated 15,600- man-hr/km . The removal
deadline for shoreline contamination was set at 1 yr.
VI. Ditches
A. Stabilization
It was expected that where water was flowing in a ditch, the
source was diverted, if possible; stabilization then proceeded
as in II- A. ' :
B. Characterization
In addition to preliminary monitoring to determine the affected
area (the area above the guideline limit), soil core samples were
c-n
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VII,
VIII,
assumed to be taken to indicate the depth of soil and sediments to
be removed. Air monitoring stations were considered to be established
on fringe areas to identify any resuspension problems, particularly
during the cleanup phase.
C. Removal
A small front-end loader (refer to III-C) was considered to be
satisfactory for removal of material from broad areas; however, a
backhoe was assumed necessary to reach confined areas. Deadline
for removal was 1 yr.
Orchards
A. Stabilization
Trees were assumed to be sprayed in an effort to wash the contamina-
tion into the orchard mat. An earthen dam was considered to be
built around the orchard v/here needed to contain runoff from the
spraying.
Character!zati on
B.
C.
It was assumed that, in addition to preliminary monitoring to
determine the extent of the affected area, soil core samples were
taken to indicate the depth of soil to be removed. Air monitoring
stations were considered established on fringe areas to identify
any resuspension problems, particularly during the cleanup phase.
Removal
It was assumed that cleanup of the orchard mat was done entirely
by a small front-end loader (refer to III-C) since larger areas
would be available for maneuvering equipment in an orchard than in
a forest area. Deadline for removal was 1 yr.
Rivers
It was expected that no attempt would be made to clean up river or
stream bottoms. Patrol of the river was assumed to be necessary to
prevent water traffic in and out of affected reaches until the extent
C-12
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of any possible risk was established. Environmental sampling locations
to test water and sediments, including shorelines, were expected to
be established at locations such as dams and river bends downstream
from the affected area, where particulate settling could occur. Sedi-
ments in settling basins at water treatment facilities near the affected
area were also considered to be analyzed periodically. This type of
monitoring might be continued less frequently after the first year.
C-13
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REFERENCES
1. A. T. Jakubick, "Migration of Plutonium in Natural Soil." Transuranium
Nuclides in the Environment. IAEA-SM-199/3, November 1975. ""—~~~~
2. J. R. Young, Procedures for Estimating Nuclear Fuel Cycle Costs
BNWL-2210, Appendix B, Battelle, Pacific Northwest Laboratories',
Rich!and, WA 99352, March 1977.
3. Tri-State Motor Transit Company, Freight Tariff Number 1070-A.
MC 109397, p. 5, effective July 26, 1977: ~——
Docket
4- Final Generic Environmental Statement on Use of Recycle Plutonium in
Mixed Oxide Fuel in Light Mater Cooled Reactors.U.S. Nuclear Regula-
tory Commission, Vol. 4, p. XI-29, August 1976.
5. W. L. Owen, W. C. Cobbin and W. E. Shelberg, Radiological Reclamation
Performance Summary. Vol. II. Evaluation and'Condensation of bata"?or
Preplanning of Recovery Operations":Naval Radiological Defense Labora-
tory, USNRDL-68-71, San Francisco, CA, September 1967.
6. P. E. James and R. 6. Menzel, "Research on Removing Radioactive Fallout
from Farmland." USDA, ARS, Tech. Bull. No. 1464, 1973.
7. R. 6. Menzel and P. E. James, "Treatments for Farmland Contaminated with
Radioactive Material." USDA, ARS, Agricultural Handbook No. 395, 1971.
8. L. E. Bruns, K. T. Key and B. A. Higley, Hanford Contaminated Sediment
Stabilization Studies. ARH-CD-640, Atlantic Richfield Hanford Company,
Richland, WA 99352, March 5, 1977.
9. W. C. Cobbin and W. L. Owen, Development and Test of a Sod-Removal
Procedure for Moist Lawns Contaminated by Simulated Fallout. USNRDC-
TR-965, Naval Radiological Defense Laboratory, San Francisco, CA,
April 1966.
10' Reactor Safety Study: An Assessment of Accident Risks in U.S. Commer-
cial Nuclear Power Plants. Appendix 71. "Calculation nf $£*?+** ArHdent
Consequences."WASH-1400, Nuclear Regulatory Commission, October 1975.
C-14
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APPENDIX D
UNIT COST DETERMINATIONS
-------
-------
APPENDIX A
UNIT COST DETERMINATIONS
BASIC COMPONENTS
The basic components upon which unit costs were based are identified
in Table D.I.
TABLE D.I. Basic Components of Unit Cost
; 1. Equipment
2. Work Crews
3. Support Personnel
4. Supplies
5. Equipment decontamination
6. Transportation to a temporary storage site
Equipment for decontamination operations was assumed to be leased on a
per month basis except for the vacuumized sweeper, which was assumed to be
purchased because decontaminating it would be difficult following cleanup
operations. For several unit cost determinations (e.g., manual earth removal
and home decontamination), no equipment cost was included in the initial
decontamination phase because this cost added insignificantly to the total
unit cost. Equipment costs for firehosing were not considered because the
equipment was assumed to be available from local fire companies. Table D.2
describes the equipment used in cleanup and lists average costs for daily
and monthly leasing.
Work crews were assumed to include equipment operators and several
laborers. Standard union wages were considered for these workers - $10.85/hr
for equipment operators and $5.41/hr for general laborers. Support personnel
would include foremen and radiation monitors. The assumption was made that
one foreman would be required for every 50 persons involved in the.decontamina-
tion operations, and one radiation monitor for every five persons. The wage
rate-was considered to be $10.20/hr for foremen and $7.56/hr for the monitors.
D-l
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TABLE D.2. Equipment Descriptions and Leasing Rates Without
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
lype or tquipment
Water-Tanker Truck
Description
9,000-gal capacity
Crop Harvester-Chopper 2-row
Farm Tractor
Front-End Loader
Front-End Loader
Grader
Sod Machine
Sod Machine
Bulldozer
Dump Truck
Plow
Vacuumi zed Sweeper
100 hp
270 hp, 5~yd capacity
100 hp, 1-1/2-yd3 capacity
12-ft blade
200 hp, 20-in. blade
10 hp, 12-in. blade
320 hp
200 hp
7- bottom
17 hp
Monthly
$2,300
1,000
2,200
5,100
1,700
2,500
3,100
1,200
7,040
1,400
450
7,500(b)
Daily
$ 77
33
73
170
56
84
103
40
235
46
15
a Costs were developed from a cost estimating guide^ and quotes by sup-
pliers, in an effort to develop average costs for the U.S.
* 'Assumed purchased.
Supply costs included in unit costs were for the long-acting soil stabi-
lizer, asphaltic emulsion, and fuels. Costs for the long-acting stabilizer
and asphaltic emulsion were obtained from Bruns, et al.(2) Ninety percent of
the estimated unit costs for the long-acting soil stabilizer ($62,500/km2)
were materials costs. The unit cost for water fixation has entirely labor
cost, due to the assumed need for repetitive application (every other day
for 2 wk). Fuel costs used were $0.428/gal ($0.110/*) for diesel fuel and
$0.60/gal ($0.16/£) for gasoline.
Factors considered in the.decontamination of equipment included costs
for labor and radiation monitors. The time required to clean one piece of
equipment was assumed to be 1 man-day each for labor and radiation monitors.
D-2
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Transportation to a temporary storage (burial) site was assumed to
involve costs for equipment (a dump truck) and truck drivers. Estimated
costs ,at the storage site included equipment (bulldozer) and equipment
operator costs. . ; . ,
The unit costs for a temporary storage site, surveillance, population
monitoring, and land reclamation presented in Table II.2 of Section II do
not follow the basic outline presented in Table D.I. The unit cost for the
temporary storage site included costs for the application of soil stabilizer
and for a guard. One guard was assumed to be on each site for 1 day per
week for a year, patrolling the perimeter of the affected area and limiting
entrance to authorized personnel only. The unit cost for population monitoring
included a portable alpha survey, nasal smears, and two urine samples per
person. An analysis cost of $100/sample was used.
Unit costs for land reclamation were provided for lawn resodding, top-
soil replacement, erosion control, and fertilizer plus seed. Lawn resodding
included both material and labor cost; the cost of the sod (U.S. average -
$0.93/m2) was approximately 99% of the total estimated unit,cost. The unit
cost for topsoil.replacement also included a cost for materials and labor,
with the materials making up about 82% of the total. The topsoil cost was
$5/yd3 ($6.5Q/m3), and the unit cost assumed replacement of the top 2 in.
(5 cm), of soil over an area of 1 km2. The unit cost for erosion control
included application of a cellulose slurry ($200/acre or $49,400 km ) and
soil stabilizer ($125/acre or $30,900/km2). The .material cost represented
^50% of the estimated unit cost for erosion control, with the remainder
being application costs. The unit cost for fertilizer plus seed was about
$200/acre ($49,400/km2). Labor for this unit cost was not added because it
was assumed that this mixture could be applied at the same time,as erosion
control materials.
Unit costs for packaging and transportation of contaminated materials
were derived from figures given in BNWL-221o'3' and by the Tri-State .Motor :
Transit Company. v' the cost of ..burial at a Federal repository .was taken
from ($60/ft3 or $i;70/m3) GESMO.^ The transportation distance was con-
sidered as 1000 miles for the reference sites. Cost estimates were based
on the following assumptions:
D-3
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• The waste container was a DOT Specification 17C 55-gal (208-n) steel drum.
Fill volume was assumed to be 7.0 ft3 (0.2 m3) per drum (approximately
90% fill).
• Cost of 55-gal drum was assumed to be $20.
• Labor costs were based on $10.00 per man-hr and assumed 1 man-hr to
fill and load a drum into a van (2 persons at 30 min/person).
• Hauling charges were calculated on the basis of $0.98/mile ($0.61/km)
one way for the 1000-mile (1600-km) shipment's).
BURDENING
All initial unit costs (see Table II.2, Section II) were burdened by
overhead (25%), loss of efficiency due to protective clothing (30%), and
workmen's compensation and social security (10%), except that the land reclama-
tion cost did not include the 30% burden for protective clothing. The 25%
burden for overhead took into account all supervisory personnel, equipment
maintenance, and administrative costs. The 30% burden for protective clothing
was based on loss of work time due to the necessity of suiting up and changing
clothing several times per day.
SAMPLE UNIT COST CALCULATION
The procedure used in calculating unit cost can be best explained by
example. The unit cost calculation for field sod removal is presented in
Table D.3. Equipment needs (machine-days/km2) were determined from equipment
removal rates. Tahio n A. n*»aean*e- 4-u« m,^u-;v,« j_ /i 2
Table D.4 presents the machine-days/km' for various pieces of
One machine-day was equated to 8 machine-hr.
decontamination equipment.
Machine-days/km2 were'then multiplied by leasing costs (Table D.2) to determine
equipment cost/km .
Crew requirements for the various decontamination operations are presented
in Table D.4. For field sod removal, one machine operator and two laborers
were assumed to work 138 days (Table D.3, pt. 2).
D-4
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TABLE D.3. Unit Cost Determination for Field Sod Removal
1) Equipment
2) Crew
• Operator
• Laborers
3) Support
• Foreman
4) Supplies
• Fuel
5) Equipment
(Decon)
Cost
138 mach-day
km
2
/ $103 A
I mach-day I
$14.214/km
138 mach-day /I man-.day\ /$86.80 \
^mach-day j \ man-day J
1^
• Laborers
• Monitors
6) Transportation
•"' Equipment
• ' Crew
Supplies
(fuel)
Equipment
(Decon)
138 mach-day /2 man-day\/$43.28 ]
\ mach-day j yman-dayy
kn>
1 Foreman (70 Days) ^p^iiEday
• Monitors 2 RM (70
\truck-day/ Iman-day
(Determined as in Part 4)
(Determined as in Part 5)
D-5
11,9807km'
11,9457km*
5,712/kin
e. KIT \ / u adys )
0.53 gal fuel /
\W-dayJ
'200 hp\ /138 mach-day V/$0.428\
hp-day \ mach / \ ^z /\ gai J
u /I man-day\/$43.28 "\
- macn ^ mach
- . /I man-<
c. macn i mach
4 trucks /jg
km2
280 truck- days
y I man-day y
ia.y\ /$60.48 \
j 1 RM-day J
days) (' $4?-, ^
uajrJy \truck-dayy
/I man-day^ /$86.80 \
6, 2607 km2
877 km2
121 /km2
12, 8807 km2
24, 3047 km2
12, 7037 km
41 5/ km
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TABLE D.3. Continued
7) Temporary Storage
* Equipment l_dpzer (70 days)
Crew
Supplies
(Fuel)
km'
70 dozer-day 1 man-^day
JZ2dozer-day
(Determined as in Part 4)
Egui pment
(Decon) (Determined as in Part 5)
$86.80
man-day
16,450/km*
6,076/km*
5.08V km'
104/km'
TOTAL
$137,000/km'
TABLE D.4. Machine-Days and Crews Required to Clean Up 1
Equipment
Harvesting-Chopping Machine
(corn)
Harvesting-Chopping Machine
(hay, soybeans)
Road Grader
Small Front-End Loader
Field Sod Machine
Lawn Sod Machine
Vacuumized Sweeper
Firehosing
Farm Tractor & Plow
Machine-Days/km
30
70
625
138
625
. 21
163
8
Crew Size
3
3
3
2
1
3
1
For costing the removal equipment and its crews (Table D.3, pt. 1 and
2), the cleanup time did not need to be known specifically. However, time
is typically a factor in costs for support personnel, equipment decontamina-
tion, transportation to a temporary storage site, and temporary site require-
ments. In-the case of field sod removal, two machines were assumed available
for removal, yielding a cleanup time of about 70 days/km2.
D-6
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Support crew costs (Table D.3, pt. 3) were based on one foreman per
50 persons and one radiation monitor per 5 persons, as discussed earlier.
Supply costs for field sod removal (Table D*3,.pt. 4) included the cost
for diesel fuel. Fuel requirements were based on the following equation:
gal fuel \/ hp
.(6)
1.53
hp-day /machine
/$/kn,2 \
Machinery decontamination included the cost for cleanup of two machines
and is shown in Table D,3, pt. 5.
For transportation of removed sod to a temporary storage site, four dump
trucks per km2 were considered available for hauling. Cost factors for trans-
portation included equipment leasing, truck drivers, fuel supply, and equipment
decontamination. Table D.3, pt. 6, shows the determination of these factors
for the field sod removal unit cost.
Temporary storage site requirements involved the use of a bulldozer to
pile removed sod. One bulldozer was considered .for, 1 km . The same cost
factors were used here as for transportation; these are outlined in Table D.3,
pt. 7.
By summing components 1-7 in Table D.3, the unburdened unit cost of
$137,000/knT for field sod removal was estimated.
REFERENCES . .."... •
1. Robert Snow Means Company, Inc., Building Construction Cost Data 1977.
Duxburg, MA 02332,1977.. >. ... , ,
2. L. E. Bruns, K. T. Key and B. A. Higley, Hanford Contaminated Sediment
Stabilization Studies. ARH-CD-640, Atlantic Richfield Hanford Company,
Rich!and, WA, March 5, 1977.
3. J. R. Young, Procedures for Estimating Nuclear Fuel Cycle Costs. BNWL-2210,
Battelle, Pacific Northwest Laboratories, Richland, WA 99352, 1977.
4. Tri-Sjtate Motor Transit Company, Freight Tariff Number 1070-A. Docket
MC 109397, p. 5, effective July 26, 1977.
5, Final Generic Environmental Statement_on Use of Recycle Plutonium 1n
Mixed Oxide Fuel in Light Water Cooled Reactors. U.S. Nuclear Regula-
tory Commission, Vol. 4, p. XI-29, August 1976.
D-7
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6. H. L. Solberg, 0. C. Cramer and A. R. Spalding, "Internal Combustion
Engines," Thermal Engineering. John Wiley & Son, Inc., pp. 189-305, 1960.
D-8
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APPENDIX E
ECOLOGICAL IMPACTS
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APPENDIX E
ECOLOGICAL IMPACTS
This appendix describes the ecological impacts that could be expected
from application of the EPA Guidance to the assumed analyses. The application
of measures that could be taken to prevent more extensive .ecological damage
is also assumed. Use of -these measures is made in the calculation of costs
for application of the Guidance.
Descriptions of three reference sites and the assumptions for decontamina-
tion were presented in Appendices A and C, respectively. In the three sub-
sections below, the ecological effects of decontamination activities are briefly
outlined for each site, according to the land types at the site and to alter-
native approaches to decontamination.
Note that ecological damage from transuranic contamination would be
unlikely if no cleanup were undertaken. In order to have radioecological
effects, it has been estimated that contamination would have to exceed
1
REFERENCE SITE ONE
Land areas assumed to be decontaminated at this site included corn fields,
idle farmland, hay and soybean fields, pasture land, forest, residential area,
and commercial area. The primary ecological effects would result from decon^
tamination of the croplands.
The options for decontamination considered involved 1) removal of the top
2 in. (5 cm) of soil, 2) plowing to a depth of 10 in. (25 cm), and 3) plowing
to a depth of 3 ft (1 m). For croplands, the first option would result in
temporary minor effects, with only normal agronomic practices required before/
the land could be returned to use. Plowing of the area is one normal practice,
therefore option 2 would result in no ecological effect. Option 3, plowing to
E-l
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a 1-m depth, would bring some subsoils to the surface, which could increase
the concentration of salt or other plant toxins at rooting depths. The lower
permeability of many subsoils might make leaching of salt difficult and result
in the need for additional soil treatment to return the area to prime produc-
tivity. However, 1-m-depth plowing might result in a lower availability of
Plutonium because the contamination would be buried below rooting depths.
Overall, of all options for decontamination of croplands discussed, plow-
ing to a 25-cm depth would have the least effect and plowing to 1-m depth the
greatest. However, all effects would be temporary and easily mitigated by
standard agronomic practices. If possible, decontamination should be sched-
uled so that fields could be available for planting in the spring.
The effects of decontamination on pasture lands would be similar to those
on croplands. Removal of the top 5 cm of soil would require revegetation in
the spring, following plowing and seed bed preparation. Options 2 and 3 would
have results similar to those for cropland. In general, effects on pasture
land would be of little consequence for this site.
Woodlot decontamination was assumed to require removal of the littermat.
This would then have to be replaced with mulch and fertilizer to restore the
nutrient supply and mitigate potential erosion problems.
Decontamination of population areas would have primarily socioeconomic
rather than ecological effects.
In general, ecological effects associated with operations to clean up
all land types would be minor and temporary. Care would need to be exercised
in order that adjacent areas not be subject to excessive perturbation.
REFERENCE SITE TWO
Decontamination of this reference site was assumed to involve forest land,
shoreline, and streams. Decpntamination procedures were assumed to require
removal of the forest mat using small front-end loaders and manual labor. An
initial water stabilizer might be used on shorelines prior to the application
E-2
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of a long-term stabilizer. Soil removal was assumed to be accomplished by use
of, a road grader, manual labor, and a small front-end loader. Streams were
considered to be monitored only. - - . , ; :
Ecological effects associated with the decontamination of forested areas
wuld be identical to those discussed for woodlots for Reference Site One.
However, the overall impact would be less because less land is involved in
this, instance. .. ' - '•'
- ' -v
Decontamination of shorelines would impact aquatic life buried in the
sand and perhaps birds nesting in the area. However, since the area is natu-
^ally disturbed by incoming tides, the impacts of decontamination would be of
limited significance.
In general, all ecological effects would be of little consequence and
would not affect the areas of concern to any substantial degree.
REFERENCE SITE THREE .
Decontamination of this reference site would entail cleanup of pasture
land, field crops, orchards, and irrigation ditches*
Impacts from the removal of the top 2 in. (5 cm) of soil at this site
would be greater than those at the two sites above because soil types here
are sandier and not as rich in nutrients. This condition would require addi-
tional soil treatment beyond that employed for the other reference sites.
Revegetation should be initiated in the fall rather than the spring because
the fall is the rainy season for this area. The site would require revegeta-
tion with nonnative grasses because there is a low probability that the area
would recover to its original state and be productive as pasture land.
Plowing to 10-in. (25-cm) and 3-ft (1-m) depths would result in impacts
similar to those at the Reference Site Two. However9 revegetation would be
Inhibited since this area has less rainfall and poorer nutrient soil types.
Agricultural land effects would be identical to those discussed for the
Reference Site Two.
E-3
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Ecological effects associated with orchards would result from the removal
of the top 2 in. (5,cm) of soil (plowing was not considered), which might
result in the loss of some trees. Many .'orchard trees are extremely shallow-
rooted and could be seriously damaged by the machinery used.
E-4
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REFERENCES < - - .: A
1. F. W. Whicker, Radioecology of Natural Systems. Fifteenth Technical'*
Progress Report to ERDA, EY-76-S-02-1156, pp. 42-43, 1977.^ ;; •-.' ••':•.-,•..
2. W. A* Rhoads, "A Wise Resolution of the Pu-Contaminated Lands5PYobleta
in Certain Parts of NTS May Be to Isolate and Maintain Them Without
Further Disturbances: A Position Paper." In: Studies of Environmental
Plutonium and Other Transuranics in Desert Ecosystems, NVO-153^Nevada
Applied Ecology Group, U.S. ERDA, Las Vegas, NV, pp. 165-180, 1976.
E-5
*US. GOVERNMENT PRINTING OFFICE: 1978 420-007/3716 1-3
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