3.1 METHODOLOGY Chapter 3 LIFE-CYCLE IMPACT ASSESSMENT

Within LCA, the LCI is a well established methodology; however, LCIA methods are less well defined and continue to evolve (Barnthouse et al., 1997; Fava et al., 1993). For toxicity impacts in particular, there are some methods being applied in practice (e.g., toxicity potentials, critical volume, and direct valuation) (Guinee et al., 1996; ILSI, 1996; Curran, 1996), while others are in development. However, there is currently no general consensus among the LCA community as to one method over another. LCIA sophistication has also been discussed in efforts to determine the appropriate level of analytical sophistication for various types of decision making requirements (Bare et al., 1999) or one that adequately addresses toxicity impacts. Section 3.1 of this chapter presents the University of Tennessee (UT) LCIA methodology, which takes a more detailed approach to chemical toxicity impacts than some methods currently being used. Section 3.1 also discusses data sources, data quality, and the limitations and uncertainties in the LCIA methodology. The UT methodology calculates life-cycle impact category indicators for a number of impact categories, including several traditional LCA impact categories (e.g., global warming, stratospheric ozone depletion, photochemical smog, and energy consumption). Furthermore, the method calculates relative category indicators for potential chronic human health, aquatic ecotoxicity, and terrestrial ecotoxicity impacts in order to address interest in human and ecological toxicity and to fill a common gap in LCIAs. Work conducted for Saturn Corporation and the EPA Office of Research and Development by the UT Center for Clean Products and Clean Technologies has provided the basis for much of this methodology (Swanson, 2001). Section 3.2 of this chapter describes the data management and analysis software used to calculate LCIA results. Section 3.3 presents the baseline LCIA results for both the CRT and the LCD. Baseline results are presented by impact category and include a discussion of the specifi