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1
Introduction
In 1984, more than 25 tons of methyl
isocyanate was released in Bhopal, India,
with devastating effects. Concern began to
focus on toxic chemical release prevention
and response strategies should a similar re-
lease happen in the United States. The U.S.
Environmental Protection Agency (EPA) in-
itiated a comprehensive evaluation of the
design and operating practices of the methyl
isocyanate production and storage units at
the one facility that manufactures the chem-
ical in the United States (EPA, 1985a). In
August 1985, the accidental release of
aldicarb oxime and several other chemical
releases from another part of that same
facility received national attention and led to
state legislation for improved prevention and
response approaches. The Bhopal disaster
and the U.S. releases underscored the paucity
of data on uses and releases of toxic sub-
stances and the need to obtain more and
better data.
Title IT} of the Superfund Amendments
and Reauthorization Act (SARA) of 1986
(P.L. 99-499; 42 USC 1 1001- 1 1050) estab-
lished several federal, state, and local
programs to address concerns about toxic
chemicals, including emergency planning,
emergency notification, and community
information needs; SARA also specified that
EPA create a toxic release inventory.
The development of Title III of SARA
was affected profoundly by the right-to-
know movement. Labor and environmental
organizations view right-to-know laws as
important to workers' and the publics un-
derstanding of toxic releases as well as to
the development of sound approaches for
reducing occupational and community
exposures. New Jersey and several local
governments already had enacted or
developed right-to-know laws before SARA
was passed in 1986.
e
SARA SECTION 313
Section 313 of Title III under SARA re-
quires industrial manufacturing facilities
using toxic chemicals to report release infor-
mation to EPA. Initial requirements for
submission of this information are specified
by EPA in the Toxic Chemical Release Re-
porting Final Rule (Federal Register, l98Sa).
The database resulting from the information
reported to EPA is referred to as the Toxics
Release Inventory (TRI).
TRI was devised to inform the public
and government officials of total routine and
accidental releases to the environment of
9
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10
certain chemicals from manufacturing facili-
ties (Federal Register, 198Sa). Section
313(h) of SARA states that information col-
lected under the TRI
shall be available . . . to inform persons
about releases of toxic chemicals to the
environment; to assist government
agencies, researchers, and other persons
in the conduct of research and data
gathering; to aid in the development of
appropriate regulations, guidelines, and
standards; and for other similar pur-
poses.
The initial list of toxic chemicals for TRI
reporting (see Appendix A) was generated
from toxic chemical lists developed by
Maryland and New jersey. This list contains
308 specific chemical compounds and 20
chemical categories and can be modified
only by a rulemaking, such as the deletion of
titanium dioxide (Federal Register, l98Sb).
The reporting requirement also applies to
chemicals transported from a facility as
waste for off-site treatment or disposal. Re-
porting is optional for chemical quantities
sent off site for recycle or reuse.
A facility must report the annual releases
of any of the listed chemicals it handles if
the facility has the following characteristics
for the specific reporting year:
· Has Standard Industrial Classification
(SIC) Code with the first two digits in the
range from 20 through 39 (manufacturing
division) (see Appendix B).
· Employs 10 or more full-time
workers.
· Handles an annual quantity of at least
one TRI-listed chemical above the following
threshold amounts: 75,000 Ib/yr in 1987,
50,000 lb/yr in 1988, or 25,000 Ib/yr in 1989
and after for listed chemicals that are
manufactured, imported, or processed; or
10,000 lb/yr for listed chemicals used in any
other manner, such as for blending,
decreasing, and coating.
Definitions for "manufacture," "process,"
and "use" of TRI-listed chemicals are broad
and wide ranging. These definitions are
presented in 40 CFR 372.3 of the Com-
munity Right-to-Know Final Rule as
follows:
M4SS BAL4NCE INFORMATION
"Manufactures means to produce,
prepare, import or compound a toxic
chemical....
~Process" means the preparation of a
toxic chemical, after its manufacture,
for distribution in commerce:
(1) in the same form or physical
state as, or in a different form
or physical state from, that in
which it was received by the
person so preparing such
chemical, or
(2) as part of an article contain-
ing the toxic chemical.
"Otherwise use" or "user means any
use of a toxic chemical that is not
covered by the terms "manufacture"
or "process" and includes use of a
toxic chemical contained in a mixture
or trade name product.
The definition of "use" for this report
(refer to Glossary) is much broader than the
one given in the Community Right-to-Know
Final Rule.
For TRI reporting, release of a listed
chemical is the discharge into the environ-
ment of the chemical through such actions as
any spilling, leaking, pumping, pouring,
emitting, emptying, discharging, injecting,
escaping, leaching, dumping, or disposing
into the environment (including the aban-
donment or discarding of barrels, containers,
and other closed receptacles).
Chemical manufacturing facilities that
produce TRI-listed chemicals in amounts
greater than the threshold are required to
report the estimated chemical releases to the
TRI. Similarly, facilities that use such
chemicals above the threshold amount must
report estimated releases. For example, a
facility that produces polyvinyl chloride
from vinyl chloride (a TRI-listed chemical)
to manufacture PVC water pipe must report
to TRI.
Reporting also is required for facilities
that use TRI-listed chemicals above thresh-
old amounts in manufacturing processes that
require no transformation of listed chemi-
cals. For example, toluene is used as a sol-
vent in blending surface coatings, such as
paint. Toluene that is shipped into a facility
as a pure solvent is shipped out of the facil
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INTRODUCTION
ity as the same chemical' but within a
coating mixture, and must be reported to
TRI.
Facilities that receive TRI-listed chemi-
cals present as raw material contaminants
(e.g., arsenic contaminants in copper ore) or
that generate byproducts during processing
(e.g., cyanide as a byproduct from coking)
are also required to report release estimates
to the TRI, if the contaminants or byprod-
ucts are present above the threshold
amounts.
TRI information is provided by facilities
annually using EPA's Form R (see Appendix
C), compiled in a computerized database,
and made available to the public. The first
reporting date for toxic releases in 1987 was
July 1, 1988. The reported information in-
cludes the following:
· Facility identification.
· Information on manufacturing, proces-
sing, or otherwise using TRI-listed
chemicals.
· Data on chemical identity.
· Estimated quantities of environmental
releases.
· Types of waste-treatment methods and
efficiencies.
· Information on waste minimization
(optional).
· Identification of all off-site locations
to which TRI-listed chemicals are
transferred.
Facilities are not required to perform any
additional monitoring or to make additional
measurements for TR} reporting beyond
those already obtained for other purposes.
EPA provided an overview of four general
methods that can be used to estimate releases
subject to TRI reporting (EPA, 1987~. EPA
described these approaches as follows:
· Calculations based on measured
concentrations of the chemical in a waste
stream and the volumetric flow rate of that
stream.
· Mass balance around entire processes
or pieces of process equipment. If input and
output (i.e., product) streams are known
(based on measured values), a waste stream
can be calculated as the difference between
input and product (accounting for accum-
ulation or depletion of the chemical in the
equipment).
11
· Emission factors, which usually express
release as a ratio of amount released to the
amount of chemical flowing through the
process. (Release estimates are obtained by
multiplying the emission factor by the
amount of chemical flowing through the
process for which estimates are needed.)
Emission factors, which are commonly used
for air emissions, are based on the average
measured emissions at several facilities in the
same industry.
· Engineering calculations and/or
judgment based on physical and chemical
properties and relationships, such as the
ideal gas law.
PURPOSE OF THIS STUDY
The Senate version of the bill that led to
SARA required reporting mass balance in-
formation in addition to information sub-
mitted by each facility reporting to the TRI.
SARA Section 313~1) 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 commercial
product or byproduct or component of a
commercial product or byproduct. For the
purpose of this report, this definition is con-
sidered to refer to mass balance data or mass
balance information. The final SARA
Section 313~1) directed EPA to obtain the
assistance of the National Academy of
Sciences (NAS) in evaluating the value and
feasibility of collecting mass balance infor-
mation to meet several national information
needs regarding hazardous chemicals (see
Appendix D).
Section 313~1~2) of SARA lists four pur-
poses of the NAS study:
1. Assess accuracy of information: "To
assess the value of mass balance analysis in
determining the accuracy of information on
toxic chemical releases" (such as data
collected for the TRI).
2. Relevance to waste reduction: "To
assess the value of obtaining mass balance
information, or portions thereof, to deter-
mine the waste-reduction efficiency of dif-
ferent facilities, or categories of facilities,
including the effectiveness of toxic chemical
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12
regulations promulgated under laws other
than this title."
3. Utility of information for chemical
management: "To assess the utility of such
information for evaluating toxic chemical
management practices at facilities, or cate-
gories of facilities, covered by this section."
4. Implications for national data develop-
ment: "To determine the implications of
mass balance information collection on a
national scale similar to the mass balance in-
formation collection carried out by the
[EPA] Administrator under paragraph (3)
[mass balance information collected by
states], including implications of the use of
such collection as part of a national annual
quantity toxic chemical release program."
The implications of mass balance infor-
mation collection on a national scale relate
not only to the three other purposes men-
tioned in the charge but also to any other
relevant implications of national collection.
The study was designed by the Academy's
National Research Council (NRC) to include
an evaluation of whether additional data and
analyses are needed to address adequately the
issues posed for the study. If the committee
determined that the potential utility of col-
lecting mass balance information warranted
further analysis, it would then propose a
second phase of the study. The second phase
would call for additional information to be
gathered to test rigorously the utility of a
national mass balance program. The NRC
design of the study is separate from SARA
Section 313~1~3), (see Appendix D), which
provides that the EPA Administrator may
"acquire mass balance information necessary
for the study from a representative number
of facilities" if currently available informa-
tion "provides an inadequate representation
of industry classes and categories to carry
out the purposes of the study." A distinction
is made between the NRC study design and
Section 313~1~3), because a recommendation
for a second phase would not necessarily be
based upon the conditions of that section.
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
M4SS BALANCE INFORMATION
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 (see
Appendix E). Further, the committee
reviewed relevant practices and experiences
of state agencies with the assistance of EPA,
the National Governors' Association (NGA),
the New Jersey Department of Environmen-
tal Protection, and the Maryland Department
of the Environment.
The term mass balance has been
used and some would say misused by
different people to mean different things.
The differences usually involve the exac-
titude 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. The
committee termed this analysis an engineer-
ing mass balance (EMBJ. 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 ~closuren). The masses
used may be total mass, masses of individual
nonreacting chemicals, or masses of
individual chemical elements or combina-
tions of elements. Valid application of EMB
requires that measurements be made with
. .
prec~s~on '.e., agreement among repeated
individual measurements of the same sample)
and accuracy (i.e., close approximation of
the actual quantities being measured). Such
measurements must be made by skilled tech-
nical 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
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INTRODUCTION
cat quantities. This approach requires less
resource-intensive accounting.
Although proponents have called this
approach a mass balance also, the committee
termed it materials accounting (MA), since it
is not truly a mass balance approach in the
technical sense. MA relies on information
that is likely to be collected routinely at a
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. MA data also can include manifest
records and data required by existing
environmental regulations. MA 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 "closured. Examples of
information used in MA are shipment
records of raw materials into a facility and
production records indicating the specific
amounts of chemicals contained in products
shipped from the facility. Analytical
measurement data obtained for an EMB
(e.g., gas chromatography measurements of
stack emissions) could also be included as
MA data.
MA data are usually what is meant by
proponents of nationwide collection of
industrial "mass balance data." For example,
at the workshop organized by the committee,
representatives from EPA and various state
governments described MA data to be what
they meant when referring to mass balance
data. An MA approach to collection of mass
balance data was also described during the
Senate deliberations leading to SARA.
13
Although both approaches provide simi-
lar types of information, EMB is more ac-
curate and precise and requires greater
technical expertise and a greater level of
effort than MA does.
ORGANIZATION OF THIS REPORT
Chapter 2 of this report reviews the EMB
and MA approaches to collecting mass
balance data. Experience with uses of MA
information is reviewed in Chapter 3, which
provides a basis for the committee's evalua-
tion of the feasibility and utility of such in-
formation to address the four information
needs posed in SARA Section 313. Chapter
4 addresses whether the accuracy of
chemical release estimates can be assessed
through EMB and MA, and the usefulness of
these two approaches in assessing waste re-
duction efficiency is explored in Chapter 5.
Chapter 6 evaluates the utility of both
approaches to toxic chemical management
practices, such as minimizing storage, avoid-
ing catastrophic releases, and providing in-
formation to the public. The implications of
collecting mass balance information on a
national scale are discussed in Chapter 7, as
well as the potential value of such informa-
tion to interested parties, including the
public; policymakers; industry; and federal,
state, and local governments. Chapter 7 also
includes the committee's recommended
approach to test a national program for toxic
substances handled by industrial facilities.
A glossary of terms and acronyms is
presented after Chapter 7.
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Representative terms from entire chapter:
balance information
