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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

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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.