The influence of value choices in life cycle impact assessment of stressors causing human health damage
De Schryver, An ; Humbert, Sebastien ; Huijbregts, Mark
In: The International Journal of Life Cycle Assessment, 2013, vol. 18, no. 3, p. 698-706
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- Purpose: This study analyzes the influence of value choices in impact assessment models for human health, such as the choice of time horizon, on life cycle assessment outcomes. Methods: For 756 products, the human health damage score is calculated using three sets of characterization factors (CFs). The CFs represent seven human health impact assessment categories: water scarcity, tropospheric ozone formation, particulate matter formation, human toxicity, ionizing radiation, stratospheric ozone depletion, and climate change. Each set of CFs embeds a combination of value choices following the Cultural Theory, and reflects the individualist, hierarchist, or egalitarian perspective. Results: We found that the average difference in human health damage score goes from 1 order of magnitude between the individualist and hierarchist perspectives to 2.5 orders of magnitude between the individualist and egalitarian perspectives. The difference in damage score of individual materials among perspectives depends on the combination of emissions driving the impact of both perspectives and can rise up to 5 orders of magnitude. Conclusions: The value choices mainly responsible for the differences in results among perspectives are the choice of time horizon and inclusion of highly uncertain effects. A product comparison can be affected when the human health damage score of two products differ less than a factor of 5, or the comparing products largely differ in their emitted substances. Overall, our study implies that value choices in impact assessment modeling can modify the outcomes of a life cycle assessment (LCA) and thus the practical implication of decisions based on the results of an LCA