PW06 Life-Cycle Assessment
Exhibit Hall
8:00 AM - Wednesday
(PW096) Comparison of Weighting Methods for the Evaluation of Supply Chain Toxic Releases.
Cicas, G.1, Hendrickson, C.1, Matthews, H. S. 1, 1 Carnegie Mellon University, Pittsburgh, PA, USA
ABSTRACT- The selection of methods in life-cycle impact assessment is very important for effective decision-making. In this presentation, the Human Toxicity Potential (HTP) is compared to the Carnegie Mellon University - Equivalent Toxicity (CMU-ET) as a potential application in the Economic Input-Output Life-Cycle Assessment (EIO-LCA) model for evaluation of supply chain toxics releases from different economic activities. The EIO-LCA model uses the Toxics Release Inventory (TRI) data of the U.S EPA to estimate the amount of released toxic chemicals related to different economic activities. E.g., one can compute the amount of various toxic emissions related to coal mining. The HTP considers the toxicity, environmental fate and exposure pathways of toxic substances, and is expressed in terms of benzene equivalent emissions to air (for carcinogens) and toluene equivalent emissions to air (for non-carcinogenic substances). The CMU-ET is calculated from threshold limit values and the gross amount of toxic emissions is expressed in terms of sulfuric acid equivalent. These indices were used to calculate the amount of toxicity-weighted chemical emissions of all 491 commodity-based U.S. industries associated with various economic activities, e.g., the amount of electricity ($10,757,100,000) consumed in Pennsylvania in 2001. The sectors in supply chains were rank-ordered and the differences in the HTP and CMU-ET results were analyzed. We conducted Monte Carlo uncertainty analyses to examine the changes of HTP and CMU-ET weighted emissions if the given sectoral TRI emission factors were considered as mean values of the real toxic releases. We found that there were significant correlations between the HTP and CMU-ET rankings, but these rankings were different from the unweighted emissions rankings.
Key words: life-cycle assessment, toxicity weighting, impact assessment