Tracking Toxic Substances at Industrial Facilities Engineering Mass Balance Versus Materials Accounting (1990) / Chapter Skim
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4. Accuracy of Toxic Chemical Release Estimates
4. Accuracy of Toxic Chemical Release Estimates
Pages 31-38
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From page 31... ...
This potential inaccuracy is based on the provision that quantities of chemical releases can be obtained from theoretical calculations, engineering estimates, or by subtracting mass balance quantities (e.g., chemical quantity purchased minus the quantity contained in the product) rather than from measurements of actual releases.
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From page 32... ...
Although it is feasible to perform EMB for individual processing steps or simple production processes, it is almost impossible to obtain complete closure in EMBs for complex industrial facilities. As discussed in Chapter 2, EMB analysis or MA practice is limited by measurement error and the assumptions or judgments necessary to implement the analysis.
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From page 33... ...
This approach to estimating releases by difference should be applied only to facilities where the input and output streams containing the chemical of interest are readily identified, and the mass balance components are of similar orders of magnitude. The quantity of releases from the facility with the decreasing operation described above probably represents the difference be
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From page 34... ...
However, MA information could provide improved public insight for understanding the nature of current releases, if the program to collect MA information were well designed and properly conducted. The usefulness of MA, supported by technical assistance and expert MASS BALANCE INFORMATION analysis, is discussed in detail in Chapter 7.
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From page 35... ...
If it is assumed that TCA is one of these substances, then the data in the four top rows of Table 4.1 are useful for comparing operations between different industries using the same listed chemical and for helping to identify large procedural errors in reported release estimates, particularly overestimates. First, the additional data would allow better comparisons to be made among manufacturers in a particular industry.
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From page 36... ...
Third, the additional data can be used to enhance efforts to validate reported releases by helping to identify large overestimates. For example, the adhesive manufacturer could mistakenly report the total mass of water and contaminants discharged, instead of reporting the mass of TCA contained in the water.
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From page 37... ...
However, EMB or MA information might be helpful for detecting gross errors in reported estimates of environmental releases and for improving understanding of chemical use patterns and environmental releases, provided that data collection is accompanied by expert technical knowledge, data validation, and analysis. MA has a better potential for these applications than EMB, because MA typically is less difficult and less expensive to obtain.
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