United States
Environmental Protection
Agency
Environmental Research
Laboratory
Athens GA 30613
Research and Development
EPA-600/S3-82-047 August 1982
Project Summary
Feasibility of Developing a
Comprehensive Methodology for
Source Identification and
Environmental Loading
(Materials Balance)
A. E. Wechsler, A. Q. Eschenroeder, D. Gilbert, K. Loos, P. Poston, and J. M.
Stevens
A materials balance is defined as an
array of the flows of materials or
chemicals from the cultural environ-
ment to the first point of entry into
the natural environment and includes
information regarding location, time
rate, quantity and chemistry of the
flows. The materials balance encom-
passes two major components —
identification of sources of materials
and estimates of environmental load-
ings. The scope and focus of a materials
balance is determined by various
characteristics, such as geographic
scale, time frame, environmental
media or chemical class.
The materials balance framework
depicts the interrelationships of con-
trolled and accidental flows of the
material in various industrial, com-
mercial and consumer activities. The
activities considered are: extraction,
refining, manufacturing, processing,
transportation, storage, use and
disposal; natural sources are also
included. A general and specific
approach to each activity is described.
A checklist is presented to assure
completeness in performing the mate-
rials balance. The checklist is a matrix
comprised of sources (activities) and
environmental inputs (flows).
Feasibility criteria are presented to
evaluate the various approaches. The
feasibility criteria are: degree of
uncertainty in source or quantities,
human resource requirements, time
constraints, identification of controll-
able sources, applicability to exposure
predictions, comprehensiveness of
the method, ability to use similar
chemicals as guides, interfacing with
fate models, accuracy of results,
compatibility with existing data,
applicability of method to different
geographic scales, resolution of re-
sults in time and space, requirements
for monitoring data, use of confidential
information, data processing demands
and complexity of input data and
method.
This Project Summary was developed
by EPA's Environmental Research
Laboratory, Athens, GA. to announce
key findings of the research project that
is fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
Materials balances have several im-
portant uses: to predict exposure in the
absence of monitoring data, to enable
confirmation and/or extension of
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limited monitoring data, and to permit
identification of critical controllable
pollutant sources as part of risk abate-
ment. Because of the limited coverage,
high cost, and extensive time require-
ments for monitoring studies, materials
balances may be the most cost effective
method of providing data for estimating
exposure. Materials balances, in some
cases, may be the only technique
available to examine the contribution of
a specific source to the ultimate risk of a
pollutant. Therefore, a comprehensive
and systematic methodology for mate-
rials balances — source identification
and loading estimation — is a valuable
part of a toxic pollutant regulatory
program.
The two major elements of materials
balances are source identification and
loading estimation. It is important to
consider and identify all major sources
— natural and anthropogenic, deliberate
and inadvertent — that can lead to
potential exposure of humans and other
biota including a.characterization of the
chemical or physical form in which the
materials are released. All processes
which result in environmental loading
— manufacture, processing, transpor-
tation, storage, disposal and others —
need to be considered. Furthermore, it is
necessary to quantify the magnitude,
location, and time dependence of the
environmental loading since these
factors form the basis for fate calculations,
subsequent concentration determinations
and exposure estimates. In the context
of this study, however, the endpoint of
the materials balance is the identification
of sources and quantification of loadings
to the "initial environmental compart-
ments," e.g., the air, water, soil in which
the release first occurs. Methods for
establishing environmental fate and
estimating exposure are not included in
the materials balance methodology
although the methodology must yield
results that are compatible with the
requirements of the environmental fate,
exposure, and risk assessment meth-
odologies.
Several materials balance studies or
approaches have been developed in the
past for specific applications. The
methods used have not been reviewed,
analyzed, summarized, or generalized to
the point where a comprehensive
approach — suitable for many types of
anticipated applications — is available.
Furthermore, the feasibility and expected
results of and resources required for
materials balances have not been
established.
The objectives of this study were to
examine the overall feasibility of a
systematic approach to source identi-
fication and environmental loading
estimation — materials balance — and
to outline the most feasible materials
balance method(s) and steps needed for
implementation, so that they can be
further developed and used in regulatory
development by EPA.
The study was structured into the
following work elements:
• First, a simplified framework for
the conduct of materials balances
was developed that included a
broad range of industrial and
consumer activities from raw
material extraction through product
disposal sources of environmental
loadings — and that could account
for routine, planned, fugitive, or
accidental environmental releases.
• Second, new materials balance
methodologies were developed for
each of these industrial/consumer
activities, incorporating existing
approaches where possible. The
methodologies were described in
sufficient detail to show how the
materials balance should be con-
ducted, giving sample calculations
and references to data and infor-
mation that could be used in a
materials balance; however, prep-
aration of a step by step or
"cookbook" method was not con-
sidered appropriate. In describing
the use and applicability of the
materials balance methods, the
feasibility criteria identified earlier
were considered.
• Third, an expansion of the checklist
or matrix approach to organizing
and presenting the results of a
materials balance was examined.
Conclusions and
Recommendations
Materials balances provide useful
data for exposure and risk assessments,
environmental fate modeling, evaluations
required as part of the Toxic Substances
Control Act and research on the
distribution and disposition of pollutants
in the environment. A number of
materials balances have been performed
and reported in the literature; most of
these materials balances are limited or
restricted. Some consider only certain
geographic regions whereas others deal
with only a limited number of industrial
or consumer activities that may produce
pollutants. Also a specific methodology
for performing materials balances has
not been developed.
A materials balance methodology
should be complete in its coverage and
adaptable to each particular case of
interest. A variety of factors determine
the usefulness and compatibility of a
methodology with a particular materials
balance program. These factors have
been summarized in feasibility criteria
developed as part of this task. A
methodology is outlined for performing
materials balances. In addition, a
checklist has been developed to assure
that all potential sources and sinks have
been evaluated in performing the
balance.
A complete materials balance must
cover all activities in which a material
participates from the point at which it
enters the cultural environment until it
returns to the natural environment. The
activities may include extraction, refining,
manufacturing, processing, transporta-
tion, storage, use and disposal. For
completeness one should also consider
natural sources of the material. Each of
these activities must be examined in
terms of inputs and outputs to the
natural environment and to other
activities. Although the general concept
is the same for each activity, a different
approach may be required for each
specific activity.
The actual method selected for a
materials balance will depend on a
number of factors. The time and
resources available for the project
determine whether a thoroughly docu-
mented evaluation or only estimates will
be accomplished. The scope of the
study, in terms of time period covered,
geographic area considered and activities
evaluated, influences selection of the
methodology. The specific material
considered and availability of pertinent
data determine whether sufficient
factual information exist, whether
estimates must be made, or whether
analogies to similar chemicals will
suffice. The desired output and use of
the materials balance is very important
in selecting a methodology. A study for
use in risk assessment would require a
different orientation and outputs from
one to provide input to fate modeling.
Each user must select those parts of the
methodology that best fit the needs of the
particular project.
The methodology and feasibility
criteria presented in the report have not
been applied in their entirety to a
materials balance. The methodology is,
in some cases, based on previous work
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but much of it represents the approach
that the authors would suggest in
performing a materials balance. Thus, a
major recommendation from the con-
clusion of this work is that the meth-
odology and criteria be tested in
performing one or more comprehensive
materials balances. This work would
evaluate the usefulness and applicability
of the methods, the feasibility criteria
and the checklist as well as providing
valuable input for modification and
revision of the methodology to make it
as useful as possible. A more detailed
step-by-step procedure could be devel-
oped as part of the documentation of this
work.
A. E. Wechsler, A. Q. Eschenroeder, D. Gilbert, K. Loos, P. Poston, and J. M.
Stevens are with Arthur D. Little, Inc., Cambridge, MA 02140.
J. W. Falco is the EPA Project Officer (see below).
The complete report, entitled "Feasibility of Developing a Comprehensive
Methodology for Source Identification and Environmental Loading (Materials
Balance)," (Order No. PB 82-239 286; Cost: $12.00, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
Athens, GA 30613
* U.S.aOVMNMINTPfllNTINO OFFIMMtW-559-017/0791
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Us.e $300
0000329
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