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Update on Impact Categories, Normalisation and Weighting in LCA

2 Selection of impact categories

• 2.1 Comprehensive list of impact categories
• 2.2 Impact categories
• 2.3 Methodological inclusion of impact categories
• 2.4 Which impact categories to choose?
• 2.5 Consideration regarding choice of impact category
• 2.6 References

The purpose of this chapter is first of all to give an overview of impact categories that are defined in different LCA methodology frameworks. The overview is formed by going through the impact categories defined in different LCA methodologies. Each impact category is described briefly and it is stated to which extend the impact category is included in the methodologies. Similarities and differences among the methods are highlighted.

The overview of geographical scaling is presented in a table in which it is indicated if the international consensus also includes the characterisation model.

The chapter also includes an overview regarding recommendations of the selection of impact categories. The overview is based on the same internationally recognised framework as just mentioned. The chapter is concluded by some general recommendations of when to apply which impact categories.

2.1 Comprehensive list of impact categories

During the recent years different national and international working groups have worked with development of characterisation methods to assign input and output data to different impact categories. The research groups have to a large extent used the work of others as a point of reference, and some persons have participated in the work of two or more groups. The methods have been improved/modified continuously e.g. by adaptation to restricted geographical areas or national conditions. As point of reference for the description and discussion of impact categories the present paper will use lists made by five different groups:

• The "Leiden list" (SETAC-Europe 1992)
• The "Nordic list" (Lindfors et al. 1995)
• The SETAC "default list" (Udo de Haes 1996)
• The "EDIP list" (Wenzel et al. 1996)
• The ISO 14047 list (preliminary) (ISO 1999)

The ISO 14047 list is a draft (ISO 1999). It only includes few impact categories. The purpose of ISO 14047 is primarily to illustrate how to work with the ISO 14040 - 14043 standards and it does not deal with which impact categorise that has to be included in LCA.

The lists of impact categories are compiled in Table 2-1.

Table 2-1
Compilation of different lists of impact categories.

2.2 Impact categories

The considered impact categories will be described briefly below with the impact categories included in the "EDIP"-method for the time being as point of reference (Wenzel et al., 1997). The description is qualitative and it includes an overview of the inventory input or output data that contribute to the specific impact categories. In the description, emphasis is placed on the geographical scaling as well as impact categories that are included.

Interrelationships between emissions, environmental impacts and their various impacts and their consequences differ from one emitted substance to another. To illustrate to examples; emission of CO₂ and CH₄, is described below.

The potential impact of the emission of CO₂ is global warming which is considered as a global effect. No matter where CO₂ is emitted the potential impact will be the same; global warming. The consequences of global warming can, among others, be; loss of human lives, loss of crops and loss habitats. The potential impact of CH₄ could be global warming as well as photochemical ozone formation. The effects of photochemical ozone formation could be local when smog is formed and it can be regional, when CH₄ is transported, and ozone is formed.

In LCA geographical scaling is divided in

• global effects,
• regional effects,
• local effect,
• working environmental effects.

Global effects and working environmental effects are relatively well defined by name, while regional and local are not very well defined terms. "Local" could be defined as impacts caused by human activity within a radius of 25 km. "Regional" could be defined as impacts cased by human activity outside a radius of 25 km but not effecting globally.

2.2.1 Global warming

Global warming - or the "greenhouse effect" - is the effect of increasing temperature in the lower atmosphere. The lower atmosphere is normally heated by incoming radiation from the outer atmosphere (from the sun). A part of the radiation is normally reflected by the soil surface but the content of carbon dioxide (CO₂) and other "greenhouse" gasses (e.g. methane (CH₄), nitrogen dioxide (NO₂), chlorofluorocarbons etc.) in the atmosphere absorb the IR-radiation. This results in the greenhouse effect e.g. an increase of temperature in the lower atmosphere to a level above normal. The possible consequences of the greenhouse effect include an increase of the temperature level leading to melting of the polar ice caps, resulting in elevated sea levels. The increasing temperature level may also result in regional climate change. Wherever greenhouse gasses are emitted they contribute to the same effect and thus the impact category is considered to be global.

All five lists include global warming as an impact category. The understanding of global warming in the lists is the same and they are generally referring to the same substances like CO₂, CH₄ and halocarbons as contributors to the impact. N₂O is included in the youngest of the lists. Further, there is also an international agreement about the characterisation model.

The impact category is described in more detail in chapter 4 in part II of this report.

2.2.2 Stratospheric ozone depletion

Decomposition of the stratospheric ozone layer is causing increased incoming UV-radiation that leads to impacts on humans, natural organisms and ecosystems. On humans the impacts can be increased incidence of i.e. skin cancer, cataracts and decreased immune defence. The primary impact on natural organisms and ecosystems is probably a decreased production of plankton in the South Pole region, and this may affect the food chain dramatically. The stratospheric ozone layer occurs at an altitude from 10 - 40 km, with maximum concentration from 15 - 25 km. The maximal generation of stratospheric ozone (O₃) occurs in the top of the stratosphere at the altitude of 40 km as a result of a reaction of molecular oxygen (O₂) and atomic oxygen (O). The reaction depends on the UV-radiation used in the decomposition of oxygen and the availability of other molecules used in the absorption of excess energy from the decomposition process. No matter where the contributing substances are emitted they contribute to the same effect, and the impact category is therefore considered to be global.

All five lists include stratospheric ozone depletion as an impact category. Further, they include the same type of substances as contributors. These are halocarbons (CFCs, HCFCs, halons, etc.). There is also international agreement about the characterisation model. The impact category is described more detailed in chapter 5 in part II of the report.

2.2.3 Photochemical oxidant formation

Photochemical ozone formation is caused by degradation of volatile organic compounds (VOC) in the presence of light and nitrogen oxide (NO_x) ("smog" as a local impact and "tropospheric ozone" as a regional impact). The biological effects of photochemical ozone can be attributed to biochemical effects of reactive ozone compounds. Exposure of plants to ozone may result in damage of the leaf surface, leading to damage of the photosynthetic function, discolouring of the leaves, dieback of leaves and finally the whole plant. Exposure of humans to ozone may result in eye irritation, respiratory problems, and chronic damage of the respiratory system.

UK AEA (United Kingdom Atomic Energy Authority) Environment and Energy Modelling and Assessment Group has been leading in the development of a "Photochemical Trajectory Model" describing the photochemical oxidant formation in the atmosphere. The model involves the following factors:

• degradation route for specific substance including information on intermediates and reactions involved in the degradation
• background level of VOCs
• background level of NO_x
• residence time of specific substance in air

Depending on the actual location for the emission of the considered VOCs scenarios can be set up and a POCP-value can be calculated for the actual case.

All five lists include formation of ozone as an impact category to be considered. Substances mentioned in the lists as contributing to the impact are: Alkanes, halogenated hydrocarbons, alcohols, aldehydes, ketones, esters, olefins, acetylenes, aromatics and other organic compounds. There is international consensus regarding the characterisation model used. The impact category is further described in chapter 6.

2.2.4 Acidification

Acidification is caused by release of protons in the terrestrial or aquatic ecosystems. In the terrestrial ecosystem the effects are seen in softwood forests (e.g. spruce) as inefficient growth and as a final consequence dieback of the forest. These effects are mainly seen in Scandinavia and in the middle and eastern parts of Europe. In the aquatic ecosystem the effects are seen as (clear), acid lakes without any wildlife. These effects are mainly seen in Scandinavia. Buildings, constructions, sculptures and other objects worthy of preservation are also damaged by e.g. acid rain. The substances contributing to acidification can be transported across boundaries via air. Acidification is rarely or not at all seen in North America. The impact category is considered to regional.

All five lists include acidification as an impact category. SO₂ and its potential for acid formation is suggested in all lists as the reference substance. Sulfur oxides, nitrogen oxides, inorganic acids (hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, hydrogen sulfide), and ammonia are mentioned as substances contributing to acidification. Inclusion of the impact category as well as the characterisation model is generally agreed upon internationally. The impact category is further described in chapter 7.

2.2.5 Nutrient enrichment

Nutrient enrichment (eutrophication) can be defined as: enrichment of aquatic ecosystems with nutrients leading to increased production of plankton, algae and higher aquatic plants leading to a deterioration of the water quality and a reduction in the value of the utilisation of the aquatic ecosystem.

The primary effect of surplus nitrogen and phosphorus in aquatic ecosystems is growth of algae. The secondary effect is decomposition of dead organic material (e.g. algae) and anthropogenic organic substances. The decomposition of organic material is an oxygen consuming process leading to decreasing oxygen saturation and - sometimes - anaerobic conditions. The anaerobic conditions in the sediment at the bottom of lakes or other inland waters may furthermore result in production of hydrogen sulfide (H₂S) which may lead to "bottom up" incidents and liberation of toxic hydrogen sulfide to the surrounding water.

The effects of nutrient enrichment of terrestrial ecosystem are seen on changes in function and diversity of species in nutrient poor ecosystems as heaths, dune heaths, raised bogs etc. and they are caused by atmospheric deposition of nitrogen compounds. Nutrient enrichment can be considered as a regional as well as local effect.

Nutrient enrichment is mentioned in all five lists. Nitrogen and phosphorous compounds are mentioned as the main origin of nutrient enrichment. However, nutrient enrichment is subject for strong development in connection with LCA. Thus, there are plentiful suggestions on how to measure the potential for nutrient enrichment. The development has moved from measurement of COD, BOD and PO43- towards NO₃-. The impact category is further described in chapter 8.

2.2.6 Effects of waste heat on water

Only one of the lists suggests effects of waste heat on water as a potential impact category. However, discharge of heat defiantly has effect at the local environment. The single suggestion can not be considered as a basis for international consensus. In all cases, the energy consumption will be part of an LCA but the possibility for better growth conditions will generally not be included. The exception is cases where the growth condition of the close surroundings might be included in the goal and scope of an LCA.

2.2.7 Human toxicity

Human toxicity is a large group of different impacts on humans. Human toxicity includes in principle all substances that are toxic to humans. It is included in all lists. The handling differs from one list to another. In different ways they include threshold values. While it can be concluded that there is some sort of international agreement about inclusion of human toxicity it is obvious that the perfect method is still to be developed. Thus it is also still a challenge to develop one - or perhaps more characterisation models. The impact category is further described in chapter 9.

2.2.8 Ecotoxicity

Ecotoxicity includes in principle all substances that are toxic to the environment. Often ecotoxicity is divided in two parts: One for terrestrial and one for aquatic environment. The aquatic often has a subcategory concerning wastewater and sludge thereof. Ecotoxicity is in all cases divided in acute and long-term effects. Depending on the environment, e.g. riverine, sea or terrestrial, the impacts can be regional as well as local.

All five lists include ecotoxicity. The Leiden list suggests a method using maximum acceptable concentration values as the starting point. The Nordic list suggests - by referring to the complexity of the subject - that different approaches are used and that all substances that have an effect on the environment are included in LCA studies. As a minimum requirement the Nordic list suggests that all substances are reported. The SETAC list includes ecotoxicity. In the list it is suggested that both possible effects and doses are included. The SETAC list refers to the EDIP as a good - for the time being - approach of handling of ecotoxicity. The EDIP includes ecotoxicity as an integrated part of the tool. The EDIP is both fate and non-fate based. In principle, all substances with an ecotoxicological potential should be included in the tool. For the time being it is mostly developed with respect to heavy metals and a number of organic substances. Tributyltin oxide, used as an ingredient in antifouling paint, is treated separately.

As for human toxicity, the characterisation models for ecotoxicity is not developed yet. Many institutions work in this area. The impact category is discussed in more details in chapter 10.

2.2.9 Working environment

Working environment or occupational health and safety are in principle impacts on humans (occupants) while being at job. Impacts can be physical and psychological. It may be impacts due to long term exposure or it may - as well - be impacts due to an accident.

Working environment is mentioned in three of the five lists. The Leiden list proposes to include number of victims by accidents. However, the definition of accidents and victims are not elaborated. The Nordic list defines the working environment more broadly and includes both chemically bound impacts and accidents. The Nordic list suggests inclusion of both a qualitative and a quantitative method. The original EDIP method is a mixture of specific assessment of processes and a general assessment on the sector level. In the suggestion for a revised method (Schmidt et al. 2001), only a sector assessment is included. By using the developed database it is possible to create an overview of the working environmental impacts in a relatively quick way, but the method is not recommended for detailed working environmental assessment of specific problems.

2.2.10 Waste

Waste can be defined as co-products without value for the producer. Depending on the nature of the waste - and the local/regional possibilities - the waste can be handled in different ways, e.g. by incineration or landfilling.

The handling of waste differs from one LCA-methodology to the other. Several waste categories have been suggested in the Leiden list, the SETAC default list and EDIP, e.g. solid waste, volume waste, hazardous and non-hazardous waste, slags and ashes and nuclear waste. The Nordic list does not include waste directly, but argues that waste handling is a part of the technical system of the LCA, requiring inputs (e.g. land) and producing output, and therefore the contribution to other impact categories from the waste management processes should be included. A method for this is currently under development in a Danish project.

Until a suitable method for treating the long-term impacts from waste management has been developed, it is suggested to characterise the waste according to the general methodology used.

2.2.11 Land use

One type of impact that relates to waste management as well as other activities is land use. The impact category is not fully operational in LCA-methodology so far, but the main suggestion is that land use is treated by including both the amount of land used for a given activity and the decrease in aesthetic value that is caused by the activity. It is also possible to include land as just one form of abiotic resources, potentially taking the quality of the land into account. Biodiversity can also be an assessment parameter.

Both the Nordic list and the Leiden list include land use as impact categories.

Heijungs (1997) gives an overview of the methods that have been proposed but concludes that none of the proposals are fully satisfying. It is therefore recommended in the present project that land use - if included in a LCA - is treated in a qualitative way.

2.2.12 Resource consumption

The main concern relating to the impact category "Resource consumption" is that use of a given resource leads to a reduced availability of the same resource for future generations.

Resource consumption can be looked upon from different angles. The most common way is to divide resources into a number of sub-categories in order to give a balanced view of the potential impacts, but the approach differs to some extent in the lists. The Leiden list and the Nordic list divides resources into material and energy resources, while the SETAC default list divide resources into biotic and abiotic resources. The Nordic list and the Leiden list also include land as a separate resource. Further, the Nordic list includes water. A common feature of all methodologies developed so far is that they use a scarcity index for the assessment, taking into account the supply adequacy of a given resource.

The methodologies focus on the use of abiotic resources. Biotic (renewable) resources does not receive the same attention, but the problem of a non-sustainable use of e.g. wood from rain forests is acknowledged.

2.2.13 Habitat alterations and impacts on biological diversity

Habitat alterations and impacts on biological diversity is in the Nordic list used to describe a variety of potential impacts. In Lindfors et al. (1995), the heading also covers non-chemical outputs like noise, smell, light, etc with a potential impact that should be considered. Finally, the heading also includes effects of oil spills, introduction of genetically modified organisms and emissions of waste heat to water. However, only a limited number of characterisation methods are assumed to be available.

2.3 Methodological inclusion of impact categories

Based on the five lists above the impact categories have been identified and categorised in groups relating to their geographical scaling and the degree of international consensus that is reached. This is illustrated in Table 2-2.

Table 2-3
Characterisation of impact categories.

G: global, R: regional, L: local, W: work environment.

1. Nielsen PH and Laursen J has recently June 2000 submitted with a substantial
input regarding classification and characterisation of noise, integration of external
noise nuisance from road and rail transportation in life cycle assessment.

Choices regarding which geographical area to choose for normalisation is dealt with in chapter 3.

2.4 Which impact categories to choose?

LCA is used for many purposes. The commissioner can be authorities, companies, consumer organisations and many other interested parties. The authorities can apply LCA in order to provide environmentally conscious public purchase, community action plans e.g. priority of packaging for beers and soft drinks and for consumer information. Companies can apply LCA in product development, environmental product information and product-oriented environmental policy. (Consumer) Organisations can apply LCA when providing environmental conscious consumption. Thus it is obviously not possible to set up specific guidelines that apply to every purpose of LCA.

2.4.1 Inclusion of different impact categories and standardisation

In the work of standardisation, great efforts have been made in order not to develop different LCA methodologies for different application of LCA; e.g. product development, environmental labelling etc.

Thus, in ISO 14040 (ISO 1997) it is stated that "Definition of the scope of the study include (among others) types of impact and methodology of impact assessment, and subsequent interpretation to be used." Further it is mentioned in connection to Life Cycle Impact Assessment that "the level of detail, choice of impacts evaluated and methodologies used depends on the goal and scope of the study."

ISO 14042 (ISO 2000) provides the following guidance regarding selection of impact categories, category indicator and characterisation models (5.3): "For most LCA studies, existing impact categories, category indicators or characterisation models will be selected. Whenever impact categories, category indicators and characterisation models are selected in an LCA study, the related information shall be referenced. .... However, in some cases existing impact categories, category indicators or characterisation models are not sufficient to fulfil the defined goal and scope of the LCA study, and new ones have to be defined. When new impact categories, category indicators or characterisation models are defined, the requirements and recommendations in this subclause also apply".

The category indicator can be chosen anywhere along the environmental mechanism between the LCI results and the category endpoint(s).

Further, it is stated that "the selection of impact categories, indicators and models shall be consistent with the goal and scope of the LCA study" and "the selection of impact categories shall reflect a comprehensive set of environmental issues related to the product system being studied taking the goal and scope into consideration"

In addition to these general recommendations it is recommended when impact categories are selected that these are environmentally relevant, internationally accepted and that double counting should be avoided.

The ISO standard does not elaborate on which impact categories should be included in different applications of LCA.

2.4.2 Inclusion of different impact categories and different methodologies

All lists used in the section about forming a maximum list include considerations about which impact categories that should be included in LCA studies. Below the approaches recommended in the lists is presented.

2.4.2.1 The Leiden methodology

The Leiden list or methodology (SETAC-Europe 1992) does not recommend inclusion or exclusion of specific impact categories compared to other impact categories. In the Leiden "methodology" it is recommended to consider a full LCA at first hand. When a full LCA and a detailed process tree is developed it might be possible to exclude parts of a full LCA. This depends, however, of the goal and scope of the study. In the methodology it is recommended not to exclude anything before justification - due to results of an inventory - is provided. The methodology includes a framework for handling a number of impact categories, see Table 2-1. These are only suggestions and are not to be regarded as exhaustive.

2.4.2.2 The Nordic methodology

The Nordic guideline (Lindfors et al. 1995) focus on "key issue identification" and therefore on studies with limited resources available. The consequence of this restriction may be that selection of a full set of impact categories is not possible due to the data requirement. The guideline conclude in general terms that:

"A "key issue identification" type LCA will never quantify all types of potential environmental impacts ..... Some impact categories will be addressed by qualitative assessments and some may even be omitted. The choice of impact categories is a subjective and free choice that depend on the goal of the study and the access to quantitative or qualitative inventory data. There is thus no strict requirement to include all potential impact types in LCA as long as: i) the choice is justified in relation to the goal of the study, ii) omitted impact categories are clearly reported, and iii) conclusions are limited to the studied impacts."

In more detailed terms the guideline presents a number of issues that should be considered when deciding which impact categories to respectively include or exclude. These considerations are i.e. completeness and practicality. Thus, it has to be ensured that all environmental problems of relevance i.e. problems which are generally regarded as major environmental problems and also problems which may be of specific significance for the systems under study, are included. On the other hand it is recommended that inclusion of too many categories should be avoided.

The Nordic methodology includes a list of potential relevant impact categories. However, the list is not claimed to be exhaustive, see Table 2-1.

2.4.2.3 The SETAC methodology of 1996

The main task of the SETAC 1996 document (Udo de Haes 1996) is impact assessment. This means that only little attention is paid to goal and scope definition and its impacts on choice of impact categories. However, it is mentioned that the default list, which is presented in Table 2-1 in this chapter, is non-exhaustive.

2.4.2.4 EDIP method

Selection of impact categories is also discussed briefly in the EDIP method, and in the light of LCA as a holistic approach, all significant resource consumption, environmental impacts and impacts on the working environment must be covered (Wenzel et al., 1998). The procedure for selection of impact categories can be expressed as:

• "Include all resource types, environmental impact categories and categories on the working environment implemented in the EDIP method.
• Consider whether some of the resource consumption and impact categories, which the EDIP method has not implemented, are significant.
• If so, include such resource consumption and impact categories. Describe and assess them quantitatively, and include them in the data on which the decision will be based together with the quantitative assessment of the impact categories implemented in the EDIP method."

In the EDIP method the procedure for selection of impact categories is followed by a list of impact categories that are ready available; see Table 2-1.

2.4.3 Summary of the advice from the methodologies

The guidance regarding choice of impact categories from all four methodologies are more or less the same, i.e. to include the impact categories that are necessary to provide a robust result. In all of the mentioned methodologies it is stressed that the default lists probably are relevant in most cases. However, the lists are not to be considered as exhaustive and other relevant impact categories can equally well be included. In conclusion, the lists do not give guidelines for when an impact category should be included or can be omitted, other than it should be determined in the goal and scope definition. Furthermore, it is stressed that LCA is an iterative process and the need for inclusion of relevant impact categories may emerge at all times during the process.

The missing guidelines apply to all applications of LCA. It is acknowledged in all lists that LCA is used for many purposes and function, but it has been an important element in the development of LCA-standards that different methods should not be used for different applications.

It is obvious that choosing to omit certain impact categories can be a way to simplify the LCA. Again, no general rules can be given and the most important aspect is that it is done in close collaboration between the practitioner and the commissioner and that the omissions are clearly stated and discussed in the report.

2.5 Consideration regarding choice of impact category

The ISO standards regarding LCA and the default lists recommend that the choice of impact categories are based on thorough considerations.

As demonstrated in Table 2-2 there is a large degree of correlation of suggested impact categories from one list to another. The lists and their underlying methodological approach do not guide the practitioner in the discussion or exclusion of impact categories for different applications of LCA. This is considered to be a never-ending task. The application of LCA is so varying that it is not meaningful to provide guidance in general term on the one hand and on the other hand it is meaningless and perhaps not possible - at least compared to the effort it would take - to prepare guidelines of the choice of impact categories per application, e.g. product comparison, eco-labelling etc.

It is recommended that the proposed impact categories in the different lists should be included in LCA studies unless there are consciously omitted. If they are omitted this should be based on sound and justified arguments. It is not an argument in itself for exclusion that a certain impact category is not quantifiable. However, this might very well in practise be an exclusion factor. If an impact category is not quantifiable it could be included qualitatively. The relevance of this depends in the end of the application of the specific LCA.

2.5.1 PC Tools

The final choice of impact categories is in the end left to the practitioner and the commissioner. In practice, however, the choice is often made along with the choice of PC-tool. Several LCA software tools exist at the market place. Best known in Denmark are undoubtedly SimaProTM, LCA Inventory Tool® and the PC-tool of EDIP (LCV). If the Danish LCV-tool is chosen for an assessment, all the impact categories in EDIP are integrated in the assessment. As the calculation of the impacts is performed automatically, there is no reason to omit some impact categories a priori.

It should be noted in this context that many of the PC-tools deals with the same impact categories, although there are differences in methods for especially the local impacts like human toxicity, ecotoxicity and waste. Most tools will therefore give a broad overview of the potential impacts, but the overview is of course not complete.

Some PC-tools only deals with the inventory analysis in LCA. In order to use this kind of tools, the practitioner has to develop his own way of handling the impact assessment phase, i.e. by establishing classification and characterisation factors and – if needed – also normalisation and weighting factors. This is obviously also resource demanding and lack of time will often cause the number of impact categories to be reduced, compared to the lists described in this project. In this case, the omission of certain impact categories should be thoroughly discussed in the goal and scope definition. The standards do not require that specific impact categories must be included, and the commissioner, the practitioner and relevant stakeholders can therefore make the final decision on what to include.

2.5.2 Inclusion of "new" impact categories

If "new" impact categories are to be included in an assessment, it may be necessary to perform parallel calculations. This could e.g. be the case if noise or land use is mentioned in the goal and scope definition as relevant impacts and the proposed methods are robust enough to handle the assessment. It is obvious that this is rather demanding in terms of time/resources, and the best solution on the longer term is of course to add the impact categories to the PC-tool.

The development in LCA-methodology is rapid. New or refined methods are being developed for some impact categories, e.g. as a result of the present Danish consensus-project where changes in the EDIP-method regarding acidification, human toxicity and the working environment have been suggested. Also, methods for new impact categories are emerging, e.g. regarding noise and land use, but none of these developments have so far been integrated in a PC-tool. Whether or not to include these impact categories is - like for all other impact categories - primarily an issue between the commissioner and the practitioner. The main criteria for inclusion is of course the relevance of the impact in the given context. A main criteria for exclusion of new or changed impact categories could be that it will be very time consuming (read: costly), and the potential for added value should be related to this in the goal and scope definition.

Some have suggested general welfare parameters like prospect of women's involvement in the labour market, children labours, welfare for animals could as well as the listed in Weidema (1993). These factors could be relevant in some cases. Inclusion of "new" impact categories as well as general welfare parameters is definitely a possibility. If a LCA practitioner choose to do so, he or she should be attentive to the fact that it might cause difficulties when classification and characterisation models are not agreed upon internationally. However, if general welfare parameters are important for a decision-maker the parameter should be included elsewhere in the assessment of the product or service in question.

2.6 References

Heijung, R., Guinée, J. & Huppes, G. 1997, Impact categories for natural resources and land use. CML report 138. Leiden University.

ISO 1999, Environmental management – Life cycle assessment – Examples of application of ISO 14042. ISO TR 14047. Working draft 1, September 1999.

ISO 1997, Environmental management - Life cycle assessment - Life cycle impact assessment. ISO/CD 14 042.1, 1997.01.15.

ISO 1997, Environmental management – Life cycle assessment – Principles and Framework. ISO 14040.

ISO 2000a, Environmental management – Life cycle assessment – Life cycle impact assessment. ISO 14042.

Lindfors, L.-G., Christiansen, K., Hoffmann, L., Virtanen, Y., Juntilla, V., Hanssen, O.J., Rønning, A., Ekvall, T. & Finnveden, G. 1995. Nordic Guidelines on Life-Cycle Assessment. Nord 1995:20. Copenhagen: Nordic Council of Ministers.

Nielsen, P.H. & Laursen, J.E. 2000, Integration of external noise nuisance from road and rail transportation in lifecycle assessment.

SETAC-Europe 1992, Life-cycle assessment. LCA Workshop, Leiden 2-3 December 1991. Society of Environmental Toxicology and Chemistry (SETAC) - Europe. Brussels.

Schmidt, A., Rasmussen, P.B., Poulsen, K.E., Fløe, T. & Andreasen, J. 2003, A new approach for incorporating the working environment in LCA. EDIP 2000 methodology. dk-TEKNIK ENERGY & ENVIRONMENT.

Udo de Haes (ed.) 1996, Towards a methodology for life cycle impact assessment. Society of Environmental Toxicology and Chemistry (SETAC) - Europe. Brussels.

Weidema, B.P. 1993, Udvikling af en metode til livscyklusvurdering af produkter, med særligt henblik på levnedsmidler (Development of a method for product life cycle assessment, with special reference to food products).

Wenzel, H., Hauschild, M. & Alting, L. 1997, Environmental Assessment of Products. Volume 1 - Methodology, Tools and Case Studies in Product Development. First edition. Chapman & Hall, London.

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