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A method for assessing the environmental impacts of freshwater consumption was developed. This method considers damages to three areas of protection: human health, ecosystem quality, and resources. The method can be used within most existing life-cycle impact assessment (LCIA) methods. The relative importance of water consumption was analyzed by integrating the method into the Eco-indicator-99 LCIA method. The relative impact of water consumption in LCIA was analyzed with a case study on worldwide cotton production. The importance of regionalized characterization factors for water use was also examined in the case study. In arid regions, water consumption may dominate the aggregated life-cycle impacts of cotton-textile production. Therefore, the consideration of water consumption is crucial in life-cycle assessment (LCA) studies that include water-intensive products, such as agricultural goods. A regionalized assessment is necessary, since the impacts of water use vary greatly as a function of location. The presented method is useful for environmental decision-support in the production of water-intensive products as well as for environmentally responsible value-chain management.

Background, Aim and Scope. In 2005 a comprehensive comparison of LCIA toxicity characterisation models was initiated by the UNEP-SETAC Life Cycle Initiative, directly involving the model developers of CalTOX, IMPACT 2002, USES-LCA, BETR, EDIP, WATSON, and EcoSense. In this paper we describe this model-comparison process and its results-in particular the scientific consensus model developed by the model developers. The main objectives of this effort were (i) to identify specific sources of differences between the models' results and structure, (ii) to detect the indispensable model components, and (iii) to build a scientific consensus model from them, representing recommended practice. Methods. A chemical test set of 45 organics covering a wide range of property combinations was selected for this purpose. All models used this set. In three workshops, the model comparison participants identified key fate, exposure and effect issues via comparison of the final characterisation factors and selected intermediate outputs for fate, human exposure and toxic effects for the test set applied to all models. Results. Through this process, we were able to reduce inter-model variation from an initial range of up to 13 orders of magnitude down to no more than 2 orders of magnitude for any substance. This led to the development of USEtox, a scientific consensus model that contains only the most influential model elements. These were, for example, process formulations accounting for intermittent rain, defining a closed or open system environment, or nesting an urban box in a continental box. Discussion. The precision of the new characterisation factors (CFs) is within a factor of 100-1000 for human health and 10-100 for freshwater ecotoxicity of all other models compared to 12 orders of magnitude variation between the CFs of each model respectively. The achieved reduction of inter-model variability by up to 11 orders of magnitude is a significant improvement.Conclusions. USEtox provides a parsimonious and transparent tool for human health and ecosystem CF estimates. Based on a referenced database, it has now been used to calculate CFs for several thousand substances and forms the basis of the recommendations from UNEP-SETAC's Life Cycle Initiative regarding characterization of toxic impacts in Life Cycle Assessment. Recommendations and Perspectives. We provide both recommended and interim (not recommended and to be used with caution) characterisation factors for human health and freshwater ecotoxicity impacts. After a process of consensus building among stakeholders on a broad scale as well as several improvements regarding a wider and easier applicability of the model, USEtox will become available to practitioners for the calculation of further CFs. Keywords: Consensus model, life cycle impact assessment, LCIA, characterization modelling, comparison, harmonisation, human exposure, toxic impact, human toxicity, freshwater ecotoxicity, comparative impact assessment, characterization factors 1 Background, Aim and Scope In ...

Purpose In recent years, several methods have been developed which propose different freshwater use inventory schemes and impact assessment characterization models considering various cause-effect chain relationships. This work reviewed a multitude of methods and indicators for freshwater use potentially applicable in life cycle assessment (LCA). This review is used as a basis to identify the key elements to build a scientific consensus for operational characterization methods for LCA. Methods This evaluation builds on the criteria and procedure developed within the International Reference Life -012-0519-3 Cycle Data System Handbook and has been adapted for the purpose of this project. It therefore includes (1) description of relevant cause-effect chains, (2) definition of criteria to evaluate the existing methods, (3) development of subcriteria specific to freshwater use, and (4) description and review of existing methods addressing freshwater in LCA. Results and discussion No single method is available which comprehensively describes all potential impacts derived from freshwater use. However, this review highlights several key findings to design a characterization method encompassing all the impact pathways of the assessment of freshwater use and consumption in life cycle assessment framework as the following: (1) in most of databases and methods, consistent freshwater balances are not reported either because output is not considered or because polluted freshwater is recalculated based on a critical dilution approach; (2) at the midpoint level, most methods are related to water scarcity index and correspond to the methodological choice of an indicator simplified in terms of the number of parameters (scarcity) and freshwater uses (freshwater consumption or freshwater withdrawal) considered. More comprehensive scarcity indices distinguish different freshwater types and functionalities. (3) At the endpoint level, several methods already exist which report results in units compatible with traditional human health and ecosystem quality damage and cover various cause-effect chains, e.g., the decrease of terrestrial biodiversity due to freshwater consumption. (4) Midpoint and endpoint indicators have various levels of spatial differentiation, i.e., generic factors with no differentiation at all, or country, watershed, and grid cell differentiation. Conclusions Existing databases should be (1) completed with input and output freshwater flow differentiated according to water types based on its origin (surface water, groundwater, and precipitation water stored as soil moisture), (2) regionalized, and (3) if possible, characterized with a set of quality parameters. The assessment of impacts related to freshwater use is possible by assembling methods in a comprehensive methodology to characterize each use adequately.Int J Life Cycle Assess (2013) 18:707-721 DOI 10.1007/s11367

Purpose Freshwater scarcity is a problem in many areas of the world and will become one of the most sensitive environmental issues in coming decades. Existing life cycle assessment (LCA) methodologies generally do not provide assessment schemes or characterization factors of the potential environmental impacts of freshwater use or freshwater resource depletion. These assessments therefore do not account for the significant environmental consequences of the loss in quality and availability of freshwater. This paper aims to develop a framework to address this methodological limitation and to support further quantitative modeling of the cause-effect chain relationships of water use. The framework includes recommendations for life cycle inventory (LCI) modeling and provides a description of possible impact pathways for life cycle impact assessment (LCIA), including indicators on midpoint and endpoint levels that reflect different areas of protection (AoP).Methodology LCI of freshwater use aims to quantify changes in freshwater availability. The key elements affected by changes in availability are sufficient freshwater supplies for contemporary human users, ecosystems, and future generations, the latter referring to the renewability of the resource. Three midpoint categories are therefore proposed and linked to common AoP as applied in LCIA. Results and discussion We defined a set of water types, each representing an elementary flow. Water balances for each type allows the quantification of changes in freshwater availability. These values are recommended as results for the LCI of water use. Insufficient freshwater supplies for contemporary human users can mean freshwater deficits for human uses, which is the first midpoint impact category ultimately affecting the AoP of human life; freshwater deficits in ecosystems is the second proposed midpoint impact category and is linked to the AoP biotic environment. Finally, the last midpoint category is freshwater depletion caused by intensive overuse that exceeds the regeneration rate, which itself is ultimately linked to the AoP abiotic environment. Depending on the regional context, the development of scenarios aimed to compensate for the lack of water for specific uses by using backup technologies (e.g., saltwater treatment, the import of agricultural goods) can avoid generating direct impacts on the midpoint impact category freshwater deficits for human uses. Indirect impacts must be assessed through an extension of system boundaries including these backup technologies. Because freshwater is a resource with high spatial and temporal variability, the proposed framework discusses aspects of regionalization in relationship to data availability, appropriate spatial and temporal resolution, and software capacities to support calculations. Conclusions