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Executive Summary
The 1984 accidental release of more than
25 tons of methyl isocyanate in Bhopal,
India, had profound consequences. In the
United States, public concern about pos-
sibilities of similar releases led to the enact-
ment of Title III of the Superfund Amend-
ments and Reauthorization Act (SARA) of
1986e Title III, a free-standing part of
SARA known as the Emergency Planning
and Community Right-to-Know Law,
established several federal, state, and local
programs for reporting and emergency plan-
ning with regard to industrial releases of
hazardous or toxic substances. Title III also
requires manufacturing facilities handling
more than specified threshold amounts of
any of 309 specified chemicals or 20 chemi-
cal categories to submit information on
environmental releases to the U.S. Environ-
mentai Protection Agency (EPA); the first
and second annual reports were submitted to
EPA on July 1, 1988 and 1989, respectively.
EPA was charged with compiling and main-
taining a database of these reports to help
government agencies and citizens obtain
information about releases of toxic
substances on the local, regional, and
national levels. This database is known as
the Toxics Release Inventory (TRI).
Although current TRI reporting require-
ments focus on information about toxic
releases, the legislative history of SARA also
showed some Congressional interest in other
kinds of information, including amass
balance"* information. The Senate bill
leading to SARA would have required man-
ufacturing facilities to report mass balance
information in order to help track flows and
assess releases of toxic materials. Proponents
of such reporting requirements argued that
mass accounting procedures would provide
essential reference data against which to
compare TRI data on waste generation and
environmental releases. Further, they argued
that such mass accounting data also would
provide a means of determining whether
TR! reporting forms were understood and
properly filled out, much as ledger-sheet
procedures and data provide valuable checks
for financial managers. In contrast, op-
ponents of this requirement questioned the
need for anything more than release data,
Section 313~1) of SARA defines mass balance as "an accumulation of the annual quantities of chemicals transported to a
facility, produced at a facility, consumed at a facility, used at a facility, accumulated at a facility, released from a facility,
and transported from a facility as a waste or as a co~runercial product or byproduct or component of a commercial product
or byproduct. Refer to the Glossary for definitions of terms used in this report.
1
OCR for page 2
2
and they expressed concerns over trade
secrets and the cost of generating mass
balance data. As a result of these conflicting
views, the House-Senate conference that led
to SARA eliminated the requirement for
nationwide mass balance data reporting and
directed EPA to obtain independent advice
from the National Academy of Sciences on
the value and feasibility of collecting mass
balance information.
The Academy's National Research Council
(NRC) was asked the following:
· To assess the utility of mass balance
analysis for judging the accuracy of infor-
mation on toxic chemical releases (e.g.,
information reported in the TRI).
· To assess the utility of mass balance
information for determining the waste-
reduction efficiency of facilities, or catego-
ries of facilities.
· To assess the utility of mass balance
information for evaluating toxic chemical
management practices at facilities or catego-
ries of facilities that report to the TRI.
· To determine relevant implications of
collecting mass balance information on a
national scale and using the information in
connection with the TRI.
The NRC suggested two phases of study:
the first phase was to address the questions
listed above to the extent practicable using
currently available nonconfidential informa-
tion; the second phase of study would be
carried out if additional data and analyses
were needed to address adequately the ques-
tions remaining from the first phase of the
study. This report presents the results of the
first phase of study.
The Committee to Evaluate Mass Balance
Information for Facilities Handling Toxic
Substances was convened by the NRC Board
on Environmental Studies and Toxicology in
November 1987. The committee comprised
members with expertise in chemistry, chem-
ical and environmental engineering, waste
management, environmental policy, infor-
mation management, and economics. In per-
forming its charge, the committee reviewed
relevant technical literature, unpublished
information, and available databases. It also
held a workshop in March 1988 to obtain
information from other persons and
organizations with special expertise.
Further, the committee reviewed relevant
Mass sAL~4NcE INFORMATION
practices and experiences of state agencies
with the assistance of EPA, the National
Governors' Association, the New Jersey
Department of Environmental Protection,
and the Maryland Department of the
Environment.
The term "mass balance" has been
used-and sometimes misused-by different
people to mean different things. The dif-
ferences usually involve the exactitude of
the data and of the data collection
procedures. The committee recognized,
therefore, that it should take into account
differing perspectives on mass balance in
addressing its charge.
To most scientists and engineers, the col-
lection and application of mass balance data
is an exacting exercise; obtaining measured
data with minimal uncertainty is emphasized.
A mass balance analysis provides a rigorous
accounting of toxic chemicals flowing
through a manufacturing facility. Th
committee termed this analysis an engineer-
ing mass balance. This type of analysis may
be applied to a chemical processing unit or
facility. The mass of inputs, outputs, and
accumulations is determined by
measurement. For each unit or for a whole
facility, the masses of inputs should
equal-or closely approximate the masses of
outputs plus accumulations (i.e., mass
balance requires "closure"~. The masses used
may be total mass, masses of individual non-
reacting chemicals, or masses of individual
chemical elements or combinations of ele-
ments. Valid application of engineering
mass balance requires that measurements be
made with precision (i.e., agreement among
repeated individual measurements of the
same sample) and accuracy (i.e., close ap-
proximation of the actual quantities being
measured). Such measurements must be
made by skilled technical personnel.
The other school of thought about mass
balance information, advocated in recent
years by some policy analysts and others,
argues that there is value in obtaining a more
approximate level of information on chemi-
cal quantities. This approach requires less
resource-intensive accounting.
Although proponents have called this also
a mass balance, the committee termed it
materials accounting, since it is not truly a
mass balance approach in the technical sense.
Materials accounting relies on information
that is likely to be collected routinely at a
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EXECUTIVE SUMMARY
facility for business or inventory manage-
ment purposes, such as records of shipments
of raw materials into a facility or records of
the specific amounts of chemicals in prod-
ucts. Materials accounting data also can in-
clude manifest records and data required by
existing environmental regulations.
Materials accounting usually refers only to
the flows of chemicals across facility
boundaries; it does not require that all input
and output data be determined (i.e., it is not
focused on closure).
Materials accounting data are usually what
is meant by proponents of nationwide collec-
tion of industrial mass balance data. For
example, at the workshop organized by the
committee, representatives from EPA and
various state governments described
materials accounting data to be what they
meant when referring to mass balance data.
A materials accounting approach to collec-
tion of mass balance data was also described
during the Senate deliberations leading to
SARA.
GENERAL CONCLUSIONS
In general, the committee concluded that
both engineering mass balance and materials
accounting can contribute to understanding
mass flows of toxic substances into and out
of a manufacturing facility. However,
inevitable limits of precision and accuracy
can make the closure required by
engineering mass balance an unachievable
objective, except for individual processing
steps or simple production processes.
Because many TRI-listed chemicals that flow
through reporting facilities occur in multiple
phases and are routed through complex pro-
cesses, engineering mass balance is of limited
practicality in the context of the TRI.
Materials accounting data are much more
easily and less expensively obtained than
engineering mass balance data. The
committee concluded that materials
accounting data, properly validated and
interpreted by persons with sufficient tech-
nical knowledge, may have better potential
for achieving the goals for the national uses
of mass balance information listed in Section
313~1) of SARA, even though such data are
less accurate and precise than engineering
mass balance data.
The committee's assessments of
3
engineering mass balance and materials
accounting information are discussed in the
following sections with respect to each type
of potential use described in Section 313~1)
of SARA.
ASSESSING THE ACCURACY OF
CHEMICAL RELEASE ESTIMATES
The committee evaluated the usefulness
of engineering mass balance and materials
accounting for providing a ledger-sheet
check upon release estimates. Accuracy
could be checked by looking for agreement
between the summed quantity of inputs of a
chemical and the sum of the outputs from a
facility. The committee also evaluated the
use of engineering mass balance and
materials accounting for assessing the
reasonableness of reported releases, in the
context of understanding the way manufac-
turing facilities produce and use toxic chem-
icals.
Engineering mass balance would only be
useful as a check on the accuracy of release
estimates if all input and output quantities
could be independently quantified and if
they were in the same general range.
However, the errors inherent in engineering
mass balance data can represent large, unac-
countable amounts of chemical mass. Even
small degrees of uncertainty can represent
large actual amounts of chemical mass that
can greatly exceed the confirmed releases.
For example, in one case considered by the
committee, a facility that produces 5 million
lb of ethylene per day, with more than 200
monitoring points, reported ethylene meas-
urements as accurate to within 1%~r 50,000
lb of ethylene per day. But this figure is
much higher than the calculated emissions
from the facility- 191 lb of ethylene per
day that was confirmed by monitoring.
Therefore, engineering mass balance would
not provide a useful check on the accuracy
of release estimates for this facility, because
the difference between the sum of inputs
and the sum of outputs would areatlv exceed
the magnitude of releases.
. ~, _
For materials accounting data, the lack
of accuracy and precision generally pre-
cludes gaining useful information on the
accuracy of chemical release estimates.
However, materials accounting could be
useful in comparing operations in a given
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4
industry or in different industries that use
the same listed chemical. It could also be
useful for assessing the reasonableness of
reported release estimates. For these
reasons, the committee concluded that the
materials accounting approach warrants
further consideration.
Release data alone generally do not
permit reliable determination of whether a
greater release of a given chemical reported
by one of two facilities occurred because
more of the chemical was processed by that
facility or because that facility was less
efficient. However, materials accounting
information on the quantities that enter both
facilities and the quantities that are shipped
out as product could assist in such a deter-
mination.
Differences in releases among different
types of industries that use identical chemi-
cals might be elucidated by the use of
materials accounting data if such data were
supported by information about the manu-
facturing processes involved. For example,
if a facility uses a chemical as a degreaser,
materials accounting data showing that none
of the chemical is shipped out as product,
together with general knowledge of how the
chemical is used, might help explain why all
of the chemical that is purchased becomes
released into the environment. In contrast,
another facility whose product contains the
same chemical might release a lower per-
centage of the chemical purchased, at least
partially because it uses the chemical dif-
ferently.
New Jersey has reported that the materials
accounting data for its Industrial Survey can
be used to assess whether reported release
estimates are valid and complete. For ex-
ample, knowing the quantities of raw
materials used and the products manu-
factured might enable recognition of a dis-
charge overestimate from a facility that mis-
takenly reports a total discharge, which
includes water, instead of just a specific
chemical in the water. Unfortunately,
underestimates are difficult to detect unless
they are drastic underestimates, such as those
that might occur if a facility using open vats
of toxic solvents reports negligible emissions
to the atmosphere.
In general, the committee concluded that
neither engineering mass balance nor
materials accounting are strictly adequate for
assessing the accuracy of estimates of
~4SS BALANCE INFORMATION
chemical releases from manufacturing
facilities. However, both of these
approaches, supplemented by expert data
validation and technical knowledge, might
be helpful for detecting gross errors in
reported estimates of environmental releases
and for improving understanding of chemi-
cal-use patterns and environmental releases.
Because materials accounting data are
potentially useful and typically less difficult
and less expensive to obtain than engineering
mass balance data, further consideration of
materials accounting information for this
purpose is warranted.
EVALUATING WASTE
REDUCTION EFFICIENCY
The committee evaluated engineering
mass balance and materials accounting for
use in helping to track waste-reduction
progress. Both were assessed for their
potential as an aid to evaluating (a) the
amount of waste generated and its relation to
the level of manufacturing activity; (b) the
extent of waste reduction at the source of
generation (versus reduction after treatment,
such as by incineration); and (c) the com-
parability of the collected data among a wide
variety of facilities.
Engineering mass balance data can be
useful in identifying and characterizing
sources of waste within a facility, but mate-
rials accounting data-specifically production
data are better for practical applications to
assess waste-reduction efficiency. Produc-
tion data can be used to normalize quantities
of generated waste; normalization gives a
ratio, for example, of pounds of waste to
pounds of chemical product or manufactured
goods. Normalization can help determine
whether a decrease in the waste generated at
a facility from one year to the next is due to
actual progress in waste reduction or to a
decrease in the proportion of production
capacity used. However, the diversity of
chemical products and manufactured goods
that involve the use of toxic chemicals often
makes it difficult to normalize waste data on
a consistent and comparable basis. Further-
more, the relationship between waste gener-
ation and production might not be linearly
correlated.
As an adjunct to a materials accounting
data collection program, expert analytical
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EXECUTIVE SUMAL4RY
assistance would be helpful in addressing
related questions, such as whether a facility's
current limited waste-reduction progress
might be the result of previous substantial
waste-reduction success, thus leaving the
facility with less opportunity for further
waste reduction. Another question to be
considered is whether waste-reduction prog-
ress has been accomplished by replacing a
chemical of known health effects with a dif-
ferent chemical of unknown health effects.
The committee concluded that neither
engineering mass balance nor materials
accounting is generally useful for strict
determination of waste-reduction efficiency
or progress in waste reduction. Both
methods fail to address technological and
economic limitations in achieving waste re-
duction. However, data on manufacturing
activity and waste generation coupled with
expert knowledge of waste-handling prac-
tices and technological options for reduction
of waste generation could, in some cases,
contribute to a useful picture of waste-
reduction progress at individual facilities.
Such data could also provide new informa-
tion to help guide additional reduction
techniques. Such facility data could not be
meaningfully aggregated at the national or
industry levels, because too much informa-
tion on individual production processes
would be lost, and waste-reduction progress
would likely be obscured. Collection of data
on each production process in multiproduct
facilities nationwide would avoid such infor-
mation loss, but assembling the data would
be difficult.
EVALUATING CHEMICAL
MANAGEMENT PRACTICES
The committee evaluated engineering mass
balance and materials accounting for their
value in providing data on (a) the types and
amounts of toxic chemicals managed by a
facility, (b) the extent to which changes in
amounts of toxic substances are attributable
to changes in levels of manufacturing
activity, (c) the comparability among
facilities, (~) the usefulness to chemical
managers for enhancing the safety of their
management practices, and (e) the usefulness
to the public and government in evaluating
whether effective practices are being used to
s
minimize releases of toxic chemicals into the
environment.
Materials accounting analysis of chemical
management practices could use available
records, such as invoices and shipping mani-
fest records; the most relevant data would be
the annual quantity of a specific chemical
transported across facility boundaries.
Expert knowledge would be required on
changes in physical and chemical properties
(e.g., from a liquid to a solid material and
from a more hazardous to a less hazardous
form) or changes in transport methods. This
information could be valuable to a
community for assessing the potential haz-
ards associated with transport practices and
for developing emergency-response plans.
The greatest quantity of a chemical
stored on site, as reported to the TRI, is
another important factor in chemical release
assessment. Data on amounts stored should
be normalized for comparison among
facilities, especially if they have very dif-
ferent production rates.
Chemical properties and reactivity,
equipment design and safeguards, operating
procedures, operator training, and quality of
maintenance and monitoring all affect the
likelihood of accidental releases. Such in-
formation is not reported in the TR! and
would not be provided through the addi-
tional reporting of materials accounting data
alone. Public access to such data could be
achieved if the reported materials accounting
data were supplemented with information
furnished by technical experts knowledge-
able about the chemical management prac-
tices at specific facilities.
The committee concluded that engineer-
ing mass balance and materials accounting
are conceptually useful for assessing and
sometimes improving management practices,
including storage, waste treatment, handling,
waste reduction, on-site tracking of toxic
chemicals, and transportation into and out of
a facility. However, information obtained
through either engineering mass balance or
materials accounting is generally inap-
propriate from a practical perspective. For
example, engineering mass balance and
materials accounting might be grossly inade-
quate for assessing transportation and storage
practices, because processes differ widely
within manufacturing facilities, thereby
limiting data comparability. Engineering
mass balance would be more useful than
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6
materials accounting for assessing waste-
treatment practices, but the practical
difficulty and cost of achieving closure re-
stricts its application. Materials accounting
does not provide the necessary process-
specific data.
Information currently reported to the TRI
does not closely link release data to chemical
management practices, except for waste
management. Additional facility-specific
information on management practices could
assist the public in evaluating whether the
most effective practices are being used to
control or prevent releases of toxic
chemicals.
COLLECTING MASS
BALANCE INFORMATION ON
A NATIONAL SCALE
Regarding the desirability of national
collection of engineering mass balance or
materials accounting data, the committee was
charged with considering relevant potential
benefits to government and society, includ-
ing the potential uses explicitly stated in
SARA Section 313~1~. The committee also
considered the costs of collection and
analysis, the complexity and interpretability
of the data, the way the data could enhance
the public's and government's understanding
of relationships between industrial
manufacturing activities and the release of
chemicals into the environment, and the
potential reporting costs to facilities provid-
ing the data, including matters of confiden-
tiality.
For specific technical applications, the
usefulness of engineering mass balance is
well established. However, it is typically
complicated and expensive, and its data col-
lection requirements go beyond the kinds of
assessments at issue here, so the collection of
engineering mass balance data was not
judged by the committee to be feasible for a
national mass balance collection program.
At the committee's request, the National
Governors' Association surveyed all 50 states
about their experiences with mass balance
information. (All the reported mass balance
analysis relied on materials accounting data.)
To date, seven states have performed a one-
time collection of mass balance information;
established a mass balance program, such as
comprehensive reporting for whole industrial
AL4SS BAIANCE INFORMATION
sectors; or collected mass balance data as a
means of demonstrating compliance with
air-pollution programs. Five other states
have plans for future mass balance efforts.
Eight states have rejected the collection of
mass balance data because of the expense
and difficulty. The remaining 29 states that
responded to the survey appear to want a
clearer demonstration that mass balance data
compilation will be cost-effective before
they commit resources for data collection.
The New Jersey Industrial Survey and
Maryland's Toxic Substances Registry
System are the two most extensive mass bal-
ance studies that have been carried out at the
state level. New Jersey, which pioneered the
use of materials accounting data, has used
data from its survey for health assessment
and surveillance. The data reportedly have
been useful in occupational health surveil-
lance for identifying workplaces in which
toxic substances are used and the numbers of
workers potentially exposed. (The New
Jersey Department of Health reported that
more than 80% of the workplaces with
potential exposures to mercury could not
have been identified without materials
accounting data.) New Jersey also reports
that its materials accounting data helped
focus the development of its Environmental
Cleanup and Responsibility Act, Toxic
Catastrophe Prevention Act, and Pollution
Discharge Elimination System. Furthermore,
New Jersey plans to use materials accounting
information to set priorities among facilities
and industries for waste-reduction attention.
Recognizing the complexity of the
materials accounting data it had collected
and the substantial potential for inaccurate
reporting, New Jersey provided expert
assistance to its survey respondents and
conducted routine field audits. Through its
extensive validation program, New Jersey
found it necessary to revise the original re-
lease estimates for approximately 25% of the
survey respondents due to gross errors in
release estimates. New Jersey officials have
stressed that, in the absence of direct field
audits or monitoring data and additional
materials accounting information, it would
have been impossible to ensure that reported
release information was valid. New Jersey's
experience with data validation was a major
factor in convincing the committee that data
obtained through a national materials
accounting program can be useful only if
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EXECUTIvE SUMMARY
augmented with expert technical assistance
for verification and analysis.
Reporting of materials accounting data
can disclose information on chemical
releases, recycling, and production, as well
as a fairly complete description of chemical
methods used, yields, and sales. Experience
with data collection through the New jersey
Industrial Survey and the New Jersey Worker
and Community Right-to-Know Act indi-
cates that these types of business information
can be kept confidential. Nonetheless, the
collection and use of confidential infor-
mation remain issues of great concern for
any potential national collection of materials
accounting data.
Maryland has reported that its Toxic Sub-
stances Registry System provided a multi-
media database that was used to establish
priorities for regulation of airborne toxic
substances and to develop a IlSt 0! tOXiC air
pollutants for which facilities must report
environmental releases. Maryland plans to
use the data in conjunction with statewide
cancer and birth defects registries and with
its occupational disease reporting system in
support of epidemiologic studies.
In general, the committee concluded that
materials accounting information, collected
and disseminated on a national scale without
the benefit of data validation and assistance
from persons with suitable expertise, would
be of little use and could potentially mislead
regulators and the public. However, a
materials accounting program might help
regulators and the public understand better
where chemicals of concern are released into
the environment provided that the data are
properly validates! and interpreted by persons
with appropriate technical knowledge about
industrial processes and chemical distribution
pathways from production to end use. Such a
materials accounting program could also aid
in the evaluation of waste-reduction ef-
ficiency and the setting of national priorities
for waste reduction and chemical
management practices.
As the logical next step in considering a
national materials accounting program
supported by expert validation and inter-
pretation, a pilot study should be conducted
on a nationwide basis to test the feasibility
and utility of collecting materials accounting
information for at least two or three
chemicals.
PILOT STUDY RECOMMENDATION
The committee recommends that a pilot
study be conducted to test the feasibility of
the national collection of materials ac-
counting information and that the study in-
clude a technical support group. The com-
mittee considers a technically supported
materials accounting program as potentially a
useful application of materials accounting
data that could enhance the public and
government understanding of relationships
between manufacturing and the environ-
mental release of chemicals, which in turn
might lead to reductions in the releases of
toxic substances into the environment.
This recommendation grows out of the
original plan for this study as suggested by
the NRC, which led to the present commit-
tee's deliberative process and review. This
plan envisioned a two-phase investigation
that would begin with a review of currently
available, non-confidential information to
evaluate mass balance options. The present
report completes the first phase. The second
phase, as recommended by the committee,
should be a pilot study involving a national
materials accounting data collection program;
it should be performed by a contractor or
through a cooperative agreement with one or
several engineering schools or research
groups, with appropriately qualified, in-
dependent oversight of the study design and
evaluation of results.
The pilot study is suggested as a prudent
step in further considering a national mate-
rials accounting data collection for all TRI-
listed chemicals from thousands of facilities.
The pilot study would obtain information to
weigh the benefits and costs of materials
accounting, and thus enable a reasoned deci-
sion on a national materials accounting pro-
gram. It also would indicate the following:
· The general feasibility of a nation-
wide collection and public dissemination of
materials accounting data designed, ana-
lyzed, and interpreted by technical experts.
· The utility of such nationwide mate-
rials accounting information (beyond the
value of TRI data) for the applications dis-
cussed in this report.
· The potential cost of such a program.
· The feasibility of conducting a na-
tional program that involves the collection of
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8
possibly sensitive or proprietary data for
eventual public use.
Any collection of materials accounting
information, even at the level of a pilot
study, will be time-consuming and expen-
sive. The data selection should be a rigorous
test of the complexity and interpretability of
materials accounting data. To maximize the
information yield relative to resources
expended, the pilot study should focus on
just two or three chemicals from the TRI
list. (Pilot study investigators could consider
studying more chemicals if resources are
available to support a larger study; however,
adding more chemicals to the pilot study
would not necessarily provide a more com-
plete answer.) It might be specified that the
selected chemicals should have important
known adverse health or environmental
effects. Or it might be better to select
chemicals used in large volumes, for two
reasons: chemicals used in large volumes
theoretically have a greater potential for sig-
nificant amounts of releases, and the
collection of materials accounting informa-
tion on chemicals used in large volumes
would provide a rigorous test of information
collection. Additional chemical-specific
questions might be designed to focus on par-
ticular risks or chemical use patterns or to
address metropolitan or regional issues.
Comparisons might be made within a single
industrial category or between industrial
categories.
The pilot study should build on the
experience of the New Jersey Industrial Sur-
vey by evaluating a national-scale testing of
all the characteristics of a materials account-
ing program, assisted by a technical support
group. It should consider all possible im-
portant releases of the few chemicals selec-
ted (i.e., from chemical uses by consumers
and nonmanufacturing industries, in addition
to those currently reporting to the TRI).
The pilot study should include an
experimental public dissemination program
designed to maximize the accessibility of a
materials accounting database supplemented
with technical support. In evaluating the
potential utility of such a materials account-
ing program, pilot study investigators
AL4SS BALANCE INFORMATION
should solicit public comments on the
disseminated information.
The pilot study should be designed to test
ways to achieve the potential benefits of
materials accounting with technical support
as cost-effectively as possible. Reliance on
data that are likely to be routinely collected
is another aspect to be evaluated. The pilot
study should address the utility of materials
accounting data aggregated at the national or
regional level, for example, as inputs to
environmental economic models used to
develop strategies for managing
environmental quality.
Existing nonconfidential data include all
release-related data currently available to
EPA, such as permit data, TRI data, and
facility management data (e.g., production
and sales information, purchase records, and
waste manifest records). They also include
monitoring data that are already being ob-
tained by federal or state programs, emission
inventories conducted under the Clean Air
Act, water quality information obtained
under the Clean Water Act, information on
the Resource Conservation and Recovery
Act hazardous waste manifests, population
densities, and information from trade
associations (e.g., production volumes and
intermediate commercial uses). Materials
accounting data collected on a regular basis
under the New Jersey Worker and Com-
munity Right-to-Know Act of 1983 should
also be considered. Validation checks are
likely to be required for some of the data.
Such checks would probably include visits to
facilities and interviews of their personnel.
In summary, mass balance information,
and in particular materials accounting
supplemented by expert data validation and
technical assistance, has potential utility
for addressing the information needs
specified in SARA Section 313. However,
the potential usefulness of a national pro-
gram cannot be clearly established without
conducting the recommended second! phase
of the study. It is the committee's consensus
that a nationwide pilot data collection per-
formed for a few chemicals would be the
appropriate next step in pursuing the
environmental protection and public-
information goals of Title III of SARA.
Representative terms from entire chapter:
mass balance
