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Background for spatial differentiation in LCA impact assessment - The EDIP2003 methodology 1 Introduction1.1 Methodology development in progress Authors: José Potting [1] and Michael Hauschild [2] The code of practice of the Society of Environmental Toxicology and Chemistry (Consoli et al. 1993), and the recent international standards and technical reports from ISO (see next section) are widely accepted as general frameworks for Life Cycle Assessment (LCA). These frameworks and technical reports are not detailed methodological references, however, since international agreement is limited to main lines and methodology has not yet been fully developed. A major problem to be solved is the poor accordance between impact as calculated in LCA and the expected occurrence of actual impact. Until recently, Life Cycle Impact Assessment (LCIA) typically focused on substance properties and left out information about the location of the emission and characteristics of – transport to – the receiving environment. Thus LCIA ignored those fate and exposure characteristics which were specified according to the conditions at the relevant locations. Here lies a source of discrepancy between modelled impact and the occurrence of actual impact (Potting and Hauschild (1997a). The need to include information about fate and exposure conditions was foreseen in the development of the EDIP97 methodology, and a site factor was defined for all non-global impact categories to represent the severity of the exposure (Wenzel et al. 1997). While a framework was set up, the development of the methodology was left for later update and EDIP97 provided only some recommendations on how to take in qualitative spatial information in the weighting step. This technical report aims to contribute to a solution of the poor accuracy of the assessed impact in typical LCA resulting from the present disregard of spatial information in LCA. The problem is set more comprehensively in Section 1.3. The subsequent chapters elaborate and present actual methodology to overcome these problems. The reporting in these subsequent chapters takes a rather well informed reader as a starting point, but a general overview of LCA and the impact assessment phase in particular is given in this introduction. Section 1.1 gives some insight in the present state of LCA methodology development as it is still in progress. Section 1.2 provides an introduction in the general framework of LCA. Section 1.3 draws the state-of-the-art of spatial differentiation in LCA when the research for this technical report started. Section 1.4 gives the problem setting and research mandate, and Section 1.5 the outline of this Technical Report. 1.1 Methodology development in progressLCA methodology developed initially mainly in the practice of conducting LCAs. This methodological freedom resulted in LCAs examining the same product, but producing quite different results, sometimes leading to opposite conclusions. Non-explicit choices and assumptions could often be identified as the source of confusion. Absence of a generally accepted methodological framework and the lack of transparency in several LCA reports seriously affected the credibility and further diffusion of LCA. The first initiative to harmonise the scientific conduct of LCA was taken in 1990 by the Society of Environmental Toxicology and Chemistry (SETAC). A series of workshops has resulted in SETACs "Code of practise" with general guidelines for LCA (Consoli et al. 1993). To further take forward methodological development, both the European and North American branch of SETAC installed a number of workgroups in 1993 for a period of 3 years. Most workgroups have documented their results in reports. These reports reflect the consensus and state-of-the-art thinking at that time within the international scientific community about:
Following this three year period, the European branch of SETAC installed new workgroups on several subjects (among which also again one on life cycle impact assessment) for another 3 year period (Udo de Haes et al. 2002). In parallel to the SETAC activities, the International Standard Organisation (ISO) started in 1994 a process of harmonisation and standardisation of the present practice of conducting LCAs. This work was completed in 2000 with a standard on principles and framework (ISO 14040 1997), a standard on goal and scope definition and inventory analysis (ISO 14041 1998) a standard on life cycle impact assessment (ISO 14042 2000) and a standard on life cycle interpretation (ISO 14043 2000). Accompanying these standards are the technical reports illustrating the use of impact assessment (ISO TR 14047), life cycle inventory data format (ISO TR 14048) and goal and scope definition and inventory analysis (ISO TR 14049). There has been quite some relations between SETAC, aiming at scientific development of methodology, and ISO, aiming at harmonisation and standardisation of the present practice. SETAC had the status of a so-called A-liaison organisation within the ISO work on LCA. This means that SETAC has had the right to delegate a representative to ISO meetings that may fully take part in the discussions. The representative had no right to vote, but ISO has sought the full and, if possible, formal backing of SETAC. (Hortensius 1996). There was also quite some overlap in people active in SETAC context as well as in ISO activities. Being from a more recent date than SETACs "Code of practise" (Consoli et al. 1993), the documents ISO 14040, ISO 14041 and ISO14042 also reflect the scientific methodological progress up to around the year 2000, though its main focus is on yet operational methodology. Besides SETAC and ISO, also LCANET has given a major input to the existing consensus regarding method development. LCANET was a concerted action under the DGXII environment and climate research and development program of the European Union with the threefold aim to establish a network of academia and industry and government, to describe the state-of-the art and to identify priority research needs. Expert-meetings were organised around five topics: positioning and application of LCA, goal and scope definition and inventory analysis, life cycle impact assessment and interpretation, work environment, databases and software. For each topic, descriptions of the state-of-the-art and a draft research program were written. These documents were discussed and research priorities were established in a series of workshops. The final results are reported in Udo de Haes and Wrisberg (1997). LCANET had a successor in CHAINET, a concerted action under the same research and development program of the European Union. CHAINET aimed to write a guidebook on the use of different analytical tools and thus had a broader focus thus than LCA only. The guidebook was written interactively with environmental stakeholders and experts of these tools (Wrisberg et al., 2002). The method development and consensus building activities of SETAC have now been continued through the joint Life Cycle Initiative with UNEP with three main pillars of which one is on life cycle impact assessment. The stated aim of the initiative is "to develop and disseminate practical tools for evaluating the opportunities, risks, and trade-offs associated with products and services over their entire life cycle to achieve sustainable development". An element under the initiative is to identify best practice for life cycle assessment within the framework laid out by the ISO standards and to make data and methodology for performing LCA available and applicable worldwide (UNEP 2002). 1.2 General frameworkSETAC's code of practice (Consoli et al. 1993), and the recent international standards and technical reports from ISO (see previous section) are widely accepted as the general framework for LCA. However, these publications do not provide detailed methodological guidance. More comprehensive and detailed guidelines are provided by the Danish EDIP methodology documentation (Wenzel et al. 1997, Hauschild and Wenzel, 1998), the Nordic guidelines (Lindfors et al. 1995), the Dutch LCA guidelines (Heijungs et al. 1992 and lately Guinée, 2002), and the North American publication with guidelines on inventory and principles (Vigon et al. 1993). Large similarities, but also some important differences exist between these "regional standards" for LCA. Those differences arise partly from regional divergences in environmental concerns and control strategies, but express also the methodological immaturity in some areas. SETAC's "Code of practice" (Consoli et al. 1993) distinguishes four methodological phases within LCA: goal and scope definition, life cycle inventory analysis, life cycle impact assessment, and life cycle improvement assessment. In the standard ISO 14040 (1997), life cycle improvement assessment is not longer regarded as a phase on its own, but rather seen as having its influence throughout the whole LCA methodology. Another phase has been added in stead: life cycle interpretations. A brief overview of the general framework is given here. Figure 1.1 presents the ISO framework for LCA (ISO 14040 1997). An important notion of ISO 14040 is the iterative character of LCA. All phases may have to be passed through more than once due to new demands posed by a later phase. Though decisions and actions may follow the interpretation phase, these decisions and action in itself are outside the framework of LCA.
Figure 1.1. The phases of an LCA according to ISO 14040 (1997). The goal definition clarifies the initial reasons, the intended application and the audience of the LCA. The main applications supported by LCA generally ask for a comparative assertion (either comparison of different products that are functionally equivalent, or comparison of the processes within the life cycle of one product). The scope definition specifies the object of the LCA and directs the specific methodology to be followed in the next phases. A particular product can provide different services and a given service can be provided by different products. The object studied in a LCA is actually a product service rather than a product itself. The functional unit, a measure for the service performance of a product, ensures that comparison of products is made on a common basis. The methodological choices about boundaries and procedures for the other phases are according to ISO 14040 specified in scope definition. Inventory analysis identifies and quantifies the resource extractions and consumptions, and the releases to the environment relating to the processes that make up the life cycle of the examined product(s). These extractions, consumptions and releases are also referred to as environmental interventions. The interventions are expressed as quantities per functional unit (and do thus not contain a specification of the temporal and spatial characteristics of these). The life cycle of a product can be divided into stages:
Each stage may consist of a number of processes which each uses one or more inputs from previous processes and gives outputs to one or more next processes. Each input can be followed upstream to its origin and each output downstream to its final end. The total of connected processes is called the product system, process tree or life cycle. Figure 1.2 gives an example of a product system.
Figure 1.2. Life cycle assessment of paper recycling looks at a system which includes forestry and production of virgin fibres and paper additives (the cradle), use of paper, collection, re-pulping and making of new paper, and disposal of worn-out paper fibres (the grave). The paper life cycle draws on other systems like transportation and energy systems which have life cycles of their own, not shown in the figure. Adapted from Hauschild and Barlaz, in prep. The system boundaries determine which processes will be included in the LCA. The definition of the product system and its boundaries takes place in scope definition. Scope definition also decides for which environmental inputs and outputs data should be collected, and about the procedure to allocate these to processes with multiple outputs to next processes. The inventory phase therefore only consists of the actual data collection and data processing. Environmental inputs and outputs have the potential to bring about several kinds of impact on the environment. In impact assessment, the potential contributions from these inputs and outputs to a collection of impact categories are estimated and weighted. As a first step (classification), the environmental inputs and outputs are assigned to the impact categories selected in scope definition. The contribution to an impact category from each input or output is then next modelled (characterisation). In very specific cases and only when meaningful, the modelling results for one impact category or subcategory may be aggregated with those of another one (valuation). Section 1.3 provides some more information about the impact assessment phase. Interpretation is the phase in which the results of the inventory phase and the impact assessment phase are combined in line with the defined goal and scope. Conclusions and recommendations to the decision-maker may be drawn, unless reviewing and revising of previous phases is needed. Both concluding/recommending and reviewing/revising should preferably be based on uncertainty and sensitivity analysis. 1.3 Spatial differentiation and threshold exceedanceThe impact assessment phase initially emerged from the wish to aggregate the large amount of inventory data to a manageable amount of interpretable impact data. For most impact categories, initially rather simple modelling was used to establish characterisation factors. These characterisation factors for emission-related impact categories were limited to equivalency assessment on the basis of intrinsic substance characteristics like the potential to release hydrogen ions (acidification assessment) or no-effect-levels (toxicity assessment). Fate and exposure modelling was not performed, nor was threshold exceedance [3] taken into account since the available data did not allow such evaluation. Already in an early stage, it was recognised that an impact assessment on the basis of substance characteristics limits the environmental relevance of the assessed impact indicators. This environmental relevance was hampered by a lack of fate and exposure modelling, and also impeded by the absence of spatial (and temporal) differentiation in the impact modelling of the non-global categories. (Fava et al. 1993) Schmidt et al. (1996), Giegrich (1996), Potting and Blok (1994 and 1995) and Owens and Rhodes (1995) provide clear examples of the erroneous results this may give rise to in LCIA. Typical characterisation factors for most impact categories did not cover modelling of fate and exposure, nor threshold exceedance and spatial differentiation. Considerable efforts were made though to incorporate generic fate and exposure modelling in the characterisation factors for toxicity assessment (Guinée et al. 1996, Hauschild and Wenzel 1998). The present toxicity factors now usually also cover fate and exposure modelling, and aggregation [4] of the calculated exposure increases from different substances is again based on no-effect-levels. Threshold exceedance, and spatial (and temporal) differentiation in fate and exposure, however, is still not taken into account in impact modelling of toxicity. The issues of spatial differentiation and threshold exceedance are among the most discussed in LCA. Though both are interrelated, they are often addressed as somewhat separate issues. Evaluation of threshold exceedance was initially left out of life cycle impact assessment due to lack of data. Meanwhile, it has for many practitioners turned into a principle in itself that is justified by the reasoning that "less pollution is better". Heijungs et al. (1992) stated: "....LCA is not concerned with the degree to which a no-effect-concentration is actually exceeded, but with the degree to which it is poten.tially filled up...". Udo de Haes et al. (1996) further underpinned this by defining LCA as "...primarily a tool for resource conservation and pollution prevention". For this reason "....all emissions are regarded as relevant on the basis of their intrinsic hazard charac.teristics, whether above or below the no-observed-effect-concentration threshold..." (White et al. 1995). Refraining from spatial differentiation in LCA, i.e. preference for a site-generic impact assessment, was and still is defended with the expected complications in inventory analysis for a more site-specific assessment. The inventory data in LCA are expressed in amounts per functional unit and in principle, nothing is known about the source-strength and variation over time of the examined processes. Due to this lack of differentiation, which is inherent to LCA, it was believed that no environmental concentrations can be predicted (and as a consequence it does neither seem possible to evaluate whether a no-effect-level is surpassed). Spatial differentiation would require for each process in the life cycle more site-specific data (Heijungs et al. 1992). On the other hand, it was commonly recognised that the calculated contributions, except for the global impacts, could be in poor accordance with the expected occurrence of actual impact [5]. The SETAC workgroup on life cycle Impact Assessment advised against evaluation of threshold exceedance. Nevertheless, they identified the elaboration of practical models for inclusion of spatial differentiation into characterisation as one of the main future tasks (Udo de Haes et al. 1996): "There seems to be a great need for further development of the procedure for site-dependent impact assessment. A main challenge then is to prepare relevant maps for the different impact categories, preferably at a world level, with a fair balance between resolving power and feasibility". The methodology presented in this Technical Report is more sophisticated than could have been foreseen in Udo de Haes et al. (1996) and EDIP97, or in Potting and Hauschild (1997b) which outlined a general approach for spatial differentiation in LCA. Presentation of interim-results drew internationally broad attention and triggered similar research activity elsewhere (that the opposite way around gave input to this research). Several sets of characterisation factors are presently available for a number of impact categories that establish the relation between the region of emission and its impact on the receiving environment. These so-called site-dependent factors do usually cover both fate and exposure, and sometimes also the exceedance of thresholds. Potting et al. in Udo de Haes et al. (2002) gives a review. 1.4 Problem-setting and research mandateDue to the lack of spatial and temporal differentiation in inventory analysis, it seems that no environmental concentrations can be predicted and as a consequence it does neither seem possible to evaluate whether a no-effect-level is surpassed. There may therefore be only little accordance between the impact predicted by LCA and the expected occurrence of actual impact. Schmidt et al. (1996), Giegrich (1996), Potting and Blok (1994 and 1995) and Owens and Rhodes (1995) provide clear examples of this. The spotted lack of accordance between the impact calculated by LCA and the expected occurrence of actual impact seriously affects the credibility of LCA. It may cause the wrong products to be taken from the market or the wrong processes within the product's life cycle to be selected for improvement. Enhancement of the impact assessment phase is therefore of vital importance for the credibility of LCA. Only little attempts have been made so far to systematically explore the feasibility of spatial differentiation in LCA. This technical report aims to contribute to a solution of the often poor accuracy of the assessed impact in LCA elaborating and presenting actual methodology to overcome this problem. Acknowledging that current life cycle impact assessment ignores spatially determined differences in exposure of sensitive targets in the environment, and that this often leads to discrepancy between predicted impacts and actually occurring impacts, the research mandate of this study was - to develop LCIA methodology which takes into account differences in exposure - applying this methodology to provide spatially differentiated characterisation factors or site factors to correct existing EDIP97 site-generic characterisation factors for all countries in Europe. 1.5 Outline of this reportThis Technical Report takes a rather well informed reader as a starting point, but a general overview of LCA and the impact assessment phase in particular is given in the previous sections. Chapter 2 elaborates on a number of issues that are of general interest for this report. The next chapters give per chapter details and background information of the methodology developed for a given impact category: acidification in Chapter 3, terrestrial eutrophication in Chapter 4, aquatic eutrophication in Chapter 5, photochemical ozone formation in Chapter 6, human toxicity in Chapter 7, ecotoxicity in Chapter 8, and noise in Chapter 9. This Technical Report contains details and backgrounds, but does not describe in its entirety how to apply the developed methodology. For this, readers are referred to the Guidance Document (Hauschild and Potting 2003) based on this Technical Report. 1.6 ReferencesBarnthouse, L., J. Fava, K. Humphreys, R. Hunt, L. Laibson, S. Noesen, J. Owens, J. Todd, B. Vigon, K. Weitz and J. Young. Life cycle impact assessment: The state-of-the-art. Pensacola (United States of America), Society of Environmental Toxicology and Chemistry – North America, 1997. Christiansen, K., A. de Beaufort-Langeveld, N. van den Berg, R. Haydock, M. ten Houten, S. Kotaji, E. Oerlemans, W-P. Schmidt, A. Weidenhaupt and R. White. Simplifying LCA: Just a cut. Brussels (Belgium), Society of Environmental Toxicology and Chemistry – Europe, 1997. Clift, R., R. Frischknecht, G. Huppes, A-M. Tillman, B. Weidema. Towards a coherent approach to life cycle inventory analysis. Brussels (Belgium), Society of Environmental Toxicology and Chemistry – Europe, 1997. Consoli, F., D. Allen, I. Boustead, J. Fava, W. Franklin, A.A. Jensen, N. de Oude, R. Parrish, D. Postlethwaite, B. Quay, J. Siéguin and B. Vigon (Eds.). Guidelines for life cycle assessment. A code of practice. Brussels (Belgium), Society of Environmental Toxicology and Chemistry – Europe and North America, 1993. Fava, J., F. Consoli, R. Denison, K. Dickson, T. Mohin and B. Vigon (Eds.). A conceptual framework for life cycle impact assessment. Brussels (Belgium), Society of Environmental Toxicology and Chemistry – Europe and North America, 1993. Giegrich, J. Personal communication, Jürgen Giegrich, Institut für Energie- und Umweltforschung, Heidelberg (Germany), 1996. Guinée, J., R. Heijungs, L. Van Oers, D. Van de Meent, T. Vermeire, M. Rikken. LCA impact assessment of toxic releases. Generic modelling of fate, exposure and effect for ecosystems and human beings with data for 100 chemicals. Leiden (the Netherlands), Centre of Environmental Science of Leiden University, 1996. Guinée, J. (ed.): Handbook on life cycle assessment. Operational guide to the ISO standards. Kluwer Academic Publishers, Dordrecht, the Netherlands. ISBN 1-4020-0228-9, 2002. Hauschild, M. and J. Potting. Spatial differentiation in life cycle impact assessment – the EDIP2003 methodology. Guideline from the Danish Environmental Protection Agency, Copenhagen, 2003. Hauschild, M. and Wenzel, H. Environmental assessment of industrial products. Vol. 2: Scientific background. London (United Kingdom), Chapman and Hall, United, 1998. Hauschild M. and Barlaz, M.: Introduction to life cycle assessment. From Christensen, T. and Barlaz, M. (eds.): Solid Waste Technology and Management (in preparation). Heijungs, R., J. Guinée, g. Huppes, R.M. Lankreijer, H.A. Udo de Haes, A. Wegener Sleeswijk, A.M.M. Ansems, P.G. Eggels, R. Van Duin en H.P. de Goede. Environmental life cycle assessment of products. Guide and background (ISBN 90-5191-064-9). Leiden (the Netherlands), Centre of Environmental Science of Leiden Univerisity, 1992 Hortensius, D. Personal communication from Dick Hortensius, employee of the Dutch Normalisation Institute, concerning process and progress in the normalisation of life cycle assessment. Delft (the Netherlands), 1996. ISO 14040. Environmental management - life cycle assessment - principles and framework. International Organisation for Standardisation (ISO), 1997. ISO 14041. Environmental management - life cycle assessment – Goal and scope definition and inventory analysis. International Organisation for Standardisation (ISO), 1998. ISO 14042. Environmental management - life cycle assessment – life cycle impact assessment. International Organisation for Standardisation (ISO), 2000. ISO 14043. Environmental management - life cycle assessment – life cycle interpretation. International Organisation for Standardisation (ISO), 2000. ISO TR 14047. Illustrative examples on how to apply ISO 14042 – life cycle assessment – life cycle impact assessment. Draft technical report. International Organisation for Standardisation (ISO), 2001. ISO TR 14048. Data format for LCA data. Draft technical report. International Organisation for Standardisation (ISO), 2001. ISO TR 14049. Illustrative examples on how to apply ISO 14041 – life cycle assessment – goal and scope definition and inventory analysis. Technical report. International Organisation for Standardisation (ISO), 2000. Lindfors, L-G, K. Christiansen, L. Hoffman, Y. Virtanen, V. Juntilla, O-J. Hanssen, A. Rønning, T. Ekval and G. Finnveden. Nordic Guidelines on life cycle assessment (Nord 1995; 20). Copenhagen (Denmark), Nordic Council of Ministers, 1995. Owens, J.W. and S.P. Rhodes. Discussion paper on the feasibility of developing characterisa.tion models for various impact categories. Submitted to ISO TC207/WG4 on behalf of the USA delegation, May 1995. Potting J. and K. Blok. Spatial aspects of life cycle impact assessment. In: Udo de Haes, H.A., A.A. Jensen, W. Klöpffer and L-G. Lindfors (eds.). Integrating impact assessment into LCA. Proceedings of the LCA symposium held at the fourth SETAC-Europe Congress, 11-14 April 1994 at the Free University of Brussels in Belgium. Brussels (Belgium), Society of Environmental Toxicology and Chemistry – Europe, 1994. Potting, J. and K. Blok. Life cycle assessment of four types of floor covering. Journal of Cleaner Production, Vol. 3 (1995), Issue 4, pp201-213. Potting, J. and M. Hauschild. Predicted environmental impact and expected occurrence of actual impact. Part 1: The linear nature of environmental impact from emissions in life-cycle impact assessment. Int. Journal of Life Cycle Assessment, Vil. 2 (1997a), Issue 3, pp171-177, 1997a. Potting, J. and M. Hauschild. Predicted environmental impact and expected occurrence of actual impact. Part 2: Spatial differentiation in life cycle assessment via de site-dependent characterisation of environmental impact from emissions. Int. Journal of Life Cycle Assessment, Vol. 2 (1997b), Issue 4, pp209-216. Potting, J., W. Klöpffer, J. Seppälä, G. Norris and M. Goedkoop. Climate change, stratospheric ozone depletiom, photooxidant formation, acidification and eutrophication. In: H.A. Udo de Haes et al. Life cycle impact assessment: Striving towards best practice. Brussels (Belgium)/Pensacola (Florida; United states of America), SETAC-Press, 2002. SETAC-EWGCRP. Life cycle assessment and conceptually related programmes. Report from the SETAC-Europe Working Group on Conceptually Related Programmes. Brussels (Belgium), Society of Environmental Toxicology and Chemistry – Europe, 1997. Schmidt, A., B.H. Christensen and A.A. Jensen. Environmentally friendly stoves and ovens (environmental project no. 338; in Danish with English summary). Copenhagen (Denmark), Danish Environmental Protection Agency, 1996. Udo de Haes, H.A. (ed.). Towards a methodology for life cycle impact assessment. Brussels (Belgium), Society of Environmental Toxicology and Chemistry – Europe, 1996. Udo de Haes, H.A. and N. Wrisberg (eds.). Life cycle assessment: state-of-the-art and research priorities. Results of LCANET, a concerted action in the environment and climate programme (DGXII). Bayreuth (Germany), Eco-Informa Press, 1997. Udo de Haes, H.A., G. Finnveden, M. Goedkoop, M. Hauschild, E. Hertwich, P. Hofstetter, W. Klöpffer, W. Krewitt, E. Lindeijer, O. Jolliet, R. Mueller-Wenk, S. Olsen, D. Pennington, J. Potting, B. Steen (eds.): Life Cycle Impact Assessment: Striving towards best practice. ISBN 1-880611-54-6, SETAC Press, Pensacola, Florida, 2002. UNEP (2002): Life Cycle Initiative homepage : http://www.uneptie.org/pc/sustain/lcinitiative/home.htm Vigon, B.W., D. Tolle, B.W. Cornaby, H.C. Latham, C.L. Harrison, T.L. Boguski, R.G. Hunt, and J.D. Sellers. Life cycle assessment: Inventory guidelines and principles (EPA/600/R-92/245). Washington D.C. (United States of America), Office of Research and Development of the Environmental Protection Agency, 1993. Weidema, B.P. (ed.). Environmental assessment of products. A textbook on life cycle assessment (3rd edition). Helsinki (Finland), UETP-EEE, 1997. Wenzel, H., Hauschild M.Z. and Alting, L.: Environmental assessment of products. Vol. 1 - Methodology, tools, techniques and case studies, 544 pp. Chapman & Hall, United Kingdom, ISBN 0 412 80800 5, Kluwer Academic Publishers, Hingham, MA. USA., 1997. White, P., B. De Smet, H.A. Udo de Haes, R. Heijungs. LCA back on track, but is it one track or two? LCA news from SETAC-Europe, Vol. 5 (1995), Issue 3, p2-5. Wrisberg, N., Udo de Haes, H.A., Triebswetter, U., Eder, P. and Clift, R. (eds.): Analytical Tools for Environmental Design and Management in a Systems Perspective. The Combined Use of Analytical Tools. Eco-efficiency in industry and science, vol. 10, Kluwer Academic Publishers, Dordrecht, 2002 Footnotes [1] Institute of Product Development (IPU) in Denmark until 2000, presently at the Center for Energy and Environmental Studies IVEM, University of Groningen [2] Institute of Product Development (IPU) in Denmark [3] Evaluation of threshold exceedance involves the comparison of a predicted environmental concentration (PEC) with a predicted no-effect-concentration (PNEC). There is anticipated risk of an effect when PEC/PNEC1, but absence of risk if PEC/PNEC<1. A typical LCA does not predict environmental concentrations, but increases of the environmental concentration (PEC). The comparison of this increase with a no-effect-concentration (PEC/PNEC) in LCA is performed only to allow aggregation of the contribution from different substances to toxicity (see also Footnote 2), and not with the aim to evaluate threshold exceedance. [4] The comparison in LCA of a concentration increase with a no-effect-concentration (PEC/PNEC) is performed only to allow aggregation of the contribution from different substances to toxicity (see also Footnote 1). The underlying assumption is that the toxicity impact from a quantity at the no-effect-concentration of a substance has the same importance as the toxicity impact from a quantity of another substance at the no-effect-concentration. In other words: If the quantities of both substances are at their no-effect-concentration, the impacts from a neuro-toxic substance and a skin irritating substance are regarded as equally important. Adding together completely different effects is one of the more serious problems in LCA, but not further addressed in this technical report. [5] This does not apply for categories as ozone depletion and the increased radiative forcing in global warming where substances distribute globally and therewith exert their impact globally.
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