social and environmental life cycle assessment (selca)

6th SETAC-Europe Meeting Life Cycle Assessment

6th SETAC-Europe Meeting: LCA - Selected Papers

Social and Environmental Life Cycle (SELCA)

Approach and Methodological Development 1Martin O'Brien, 2Alison Doig, 2Roland Clift

i Dept. of Sociology, 2Centre for Environmental Strategy University of Surrey, Guildford, Surrey, GU2 5KX, UK

Corresponding author: Martin O'Brien

Assessment

Abstract Social and Environmental Life Cycle Assessment (SELCA) is an analytical tool for profiling and evaluating the interaction between the social and technological systems within the life cycle of given service. Environmental Life Cycle Assessment (ELCA) and Social Life Cycle Assessment {SLCA} are undertaken with their own objectives using independent methodologies. Integrating the outcomes of the two assessments provides more comprehensive and insightful de- scriptions of the potential impacts of a life cycle, including the key social factors through which the life cycle is sustained and modified. The SELCA approach is outlined using the examples of two fuel cycles of coal and waste in energy-generation. There are some methodological issues in combining ELCA and SLCA which we highlight in order to encourage further work on the integration of environmental and social processes in LCA.

Keywords: LCA; social life cycle; integrated approach; environmental life cycle; SELCA

1 I n t r o d u c t i o n

The concept of 'sustainable development' (or 'sustainability') was introduced by the United Nations in the Brundt- land declaration but has eluded precise definition. In very broad terms, sustainable development means a pattern of human activity that is consistent with the ecological and thermodynamic maintenance of the planet, which is tech- nically and economically viable, and which meets people's needs and expectations (O'BRIEN et al., 1996a; 1996b). The idea is summed up in Figure 1. 'Sustainable Development' is the area at the centre of the diagram where the 'natural ' , ' techno-economic' and 'social' intersect. Environmental Life Cycle Assessment (ELCA) has been developed as a decision-support tool to compare the impacts on the natural world of different techno-economic ways to meet human needs, defined narrowly as material needs. However, ELCA attempts to take a broad view in examin- ing the flows of materials and energy from the 'cradle ' of primary resources through to the 'grave' of emissions or

Int. J. LCA 1 (4} 231-237 (1996) �9 ecomed publishers, D-86899 Landsberg, Germany

Fig. 1: Components of sustainable development

stable residues. In this paper, we outline a procedure for in- troducing the third area of the diagram - social and politi- cal processes - through a social life cycle assessment (SLCA). We call the combined approach Social and Envi- ronmental Life Cycle Assessment (SELCA). Examples re- ferred to in the discussion are drawn from our own research into coal and waste as fuels for energy generation but the procedure should have much wider application in industrial development and social planning. Current environmental assessments are usually concerned with specific types of impact. Once a project is defined (in broad terms) its likely contribution to specific environmental hazards - greenhouse gases, toxins, water quality, and so on - is assessed in quantitative terms. The quantitative, technological dimensions of assessment take precedence over the qualitative, socio-economic dimensions. SELCA provides an opportunity to shift this emphasis in order to investigate which social sectors are generating which environmental impact channels and how the channels are organised and sustained. In other words, SELCA indicates both the quantitative direct and indirect environmental impacts and the social determination of the impact routes, their organisation and control. The value of the approach lies in establishing what social action, as well as what technical developments, may be undertaken in order to effect

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Li fe C y c l e A s s e s s m e n t 6 th S E T A C - E u r o p e M e e t i n g

positive change within the industrial or commercial cycle under investigation. ELCA and SLCA begin from different methodological standpoints stemming from differences in disciplinary ori- entation. For ease of reference we have listed some of these important differences in Table 1. The differences in disciplinary perspective, origin of data, methodological standpoint and conceptions of the processes under study had two important consequences for our research. The first was the adoption of a much more complex model of the contents and consequences of the industrial or commercial life cycle, including qualitative dimensions of life cycle processes as well as quantitative ones. The second consequence, potentially a greater source of analytical problems, was the use of the SLCA to track the socio-ec0nomic 'channels' through which environmental burdens arise and are distributed but without reference to the 'functional unit' which is the basis of the ELCA. Al- though there are methodological problems in the integration of SLCA and ELCA, nonetheless, we contend that combining engineering and social science data and, to a lesser extent, perspectives makes the process of assessment both more transparent and more complete. This is because the axes and foci of evaluation, together with the components of the different impact streams, are specified both in terms of the technical systems through which goods and services are generated and the social processes - of production, use or re-entry of depositions, for example, - through which technical systems operate (c.f., DOIG et al., 1994). Such social processes are not only site specific but include the development of official classifications of materials (defining 'waste ' as a 'fuel', for example), embedded logics in planning and monitoring frameworks (the persistence of case-by-case approaches to planning applications, for example) and the interactions between different policy sectors and their impact on the circulation of environmental hazards (the shifting responsibilities for clinical wastes or the confusion between different development agenda, including ambiguities surrounding which policies and prac- tices fall under the rubric of competitive economic development and which under the rubric of sustainable development and also conflicts over support for public versus private transport systems, for example).

2 Aims and Object ives

The purpose of carrying out a SELCA is to provide a structured yet flexible way to identify the factors that must be reconciled in making strategic and planning decisions for a sustainable society. Specifically, SELCA aims to:

1. provide techniques for combining environmental and sociological assessments of alternative systems which can satisfy human need in both operational and strategic terms;

2. establish an assessment f ramework that incorporates both scientific/technical and social/strategic evaluations of these options.

The objectives of SELCA are to:

1. identify the key operational and regulatory components of the systems;

2. profile the interactions between the contributory co- systems;

3. assess where and how environmental information can influence operational performance, monitoring and management;

4. conduct sensitivity studies of how policy and operational changes in the system will affect overall social and environmental impacts and performance;

5. provide data of sufficient quality to allow informed operational and strategic decision-making about the system.

In developing this approach, we have investigated energy systems as a specific example. This paper, therefi)re, con- centrates on the fuel cycles, where the recognised environmental problems are consumption of non-renewable resources and emissions which have environmental impacts at the global (e.g., 'greenhouse' gases), 'regional' (e.g., acid deposition) and local (e.g., human- and eco-toxicity) scales. We do not have the space to outline how each of the aims and objectives were met. A full account is contained in O'BRtEN et al. (1996a; see also DOIG & ELLISON, 1995). Here we focus on outlining some of the main elements of our approach to assessing the interactions between social and environmental processes. In our own research (O'BRIEN, CLIFT & DOIG, 1996a; 1996b), the Environmental Life Cycle Assessment (ELCA)

Table 1: Disciplinary differences in LCA perspective

Methodological Issue Social Science Engineering

concept of 'cycle' and its consequences unstable process with complex and shifting stable process with fixed boundaries; analytical boundaries; analytical focus on system intercon- focus on linear connections between compo-

! nections; reproduction of variability nent parts; repetition or continuity of impacts

Socio-economic processes constitute the sys- socio-economic processes provide 'feedback'to connection between 'system' and socio-eco- tern and give rise to environmental burdens technical operations and may influence environ- nomic process mental burdens

largely 'primary' (i.e., collected by the' some operations described by process-specific nature of data researchers using specially designed methods) data but not usually collected by the resear-

combined with 'secondary' (i.e., derived from chars; some use of data provided by operators other research on the issue under investigation or on reEated processes)

bottom-up, 'disaggregated' approach to system top-down, 'whole system' approach to system methodological standpoint ~rocesses life cycle

232 ~nt. J. LCA 1 (4) 1996


and the Social Life Cycle Assessment (SLCA) were conducted independently. This is because the methodology for researching the 'social life cycle' of the fuel systems had to be developed without any previous guidelines on which to draw. A central aim of the research, however, was to rec- ommend methodological procedures for a combined research strategy. We begin with the acknowledgement that both ELCA and SLCA assume that any given fuel system will be dependent on or structured by contributory co-systems. The organisation of transportation systems, materials supply and sorting systems, for example, structure both the (lack of) availability of policy targets (for example, the op- tion to use different forms of transport, the source reduction of waste) and the aggregated burdens of the fuel supply system. Here, we outline an assessment procedure aimed at focusing on these connections in which SLCA and ELCA are conducted in parallel, with goal/problem definition, data collection and analysis, inventory and process assessment, and process evaluations intersecting at key points. These points revolve around strategic, planning processes oriented towards consistent and coherent environmental policy development. The SELCA methodological procedure responds to key issues in community consultation and environmental planning identified in the literature. These include the need to consider the environmental impacts of the whole system and its interactions with other systems, rather than only

site-specific impacts. A second issue is the need to develop plans and protocols for environmental monitoring and management that draw on the inputs of a wide range of affected and interested constituencies. The assessment procedure is represented in diagrammatic form as Figure 2. 'FG' in this figure refers to 'Focus Group'. The outline is meant to illustrate how a SELCA can be conducted in the context of a consultative and publicity framework relating to environmental management and monitoring.

3 SELCA Methodology

The following outline describes the steps involved in SELCA as a research tool and how the assessment framework can assist in planning for infrastructure projects such as fuel management systems. Each step addresses social and technical questions about environmental planning and monitoring.

3.1 Problem/Goal definition

Environmental problems have many different dimensions. It cannot be assumed that the problems identified by a planner, developer, local authority, or energy company, for example, are either the same problems identified by any other member of the list or the same as those identified by

SLCA

Problem definition scoping)

Data analysis )

Process assessment )

Evaluation )

Action 3

Planning process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C ( Stakeholders 3 n ~ S U I t a t i fO In

~2222222222222f------ZZZ-2-2-E [ Public briefing )

U b I i C i t Y

[ Public response

I f Environmental i I A | strategy | I e | (Examples of selca issues) | I ! itransporl minimisation|

/ Monitoring: I / Energy Efficiency I

I I n | Alternative source/use I I L Resource Efficiency ) I I

ELCA

Goal definition/Scoping 3

Inventory analysis )

Impact assessment )

Evaluation )

Action )

Fig. 2: SELCA process and assessment scheme

Int. J. LCA 1 (4) 1996 233

Life Cycle Assessment 6th SETAC-Europe Meeting

the communities and groups affected by the operation of the fuel-cycle. SELCA presupposes that problem definition arises out of consultation with and negotiation among different interest groups. Focus groups (or focus panels) can be arranged in which representatives of different interested sectors (industry, residents, local authority departments, health and social services, pressure groups, specialist environmental and social research organisations, and so on) meet to define the environmental and social dimensions of local problems. This process is important because community consultation methods often begin some way down the development road, after agenda have been set and plans and goals for- mulated by specific interest groups. Consultation with stakeholders can help clarify the scope of the environmental impacts of the industrial process (waste distribution, energy use, coal production, and so on) under consideration and can lead to social and technical options for addressing them. When the environmental problems have been clarified, the goals of the study and the extent of the system to be examined can be fixed to reflect the major concerns expressed in the consultation exercise. The specific services that are required from the industrial process - the supply of electricity, the heating of homes, the minimisation and disposal of waste, etc. - can then bc stated as the functions required from the system(s). Func- tion and prohlem definition can thus be combined during consultation in prcparation for undertaking the SEI.CA. A statement of the dimensions of the process and options for change or development can he produced. This can bc drafted by the environmental strategy section of a local authority or company in conjunction with independent research advisors chosen by the focus groups or focus panels, for example. This statement can be used in wider publicity about proposed changes.

3.2 Scoping

Once the SELCA goals are established clearly, the scoping exercise will identify the initial technical, environmental and social parameters associated with different ways of achieving the same goals. Scoping involves the preliminary research work needed to construct the framework for the detailed SELCA. Important operational and regulatory processes need to be identified and sources of information need to be specified. Scoping will define the geographic and temporal boundaries of the study, the methodological approach, the as- sumptions made and the range of process components to be included. For the specific case of an energy system, social and environmental characteristics of the fuel cycles are identified during the scoping exercise, such as responsibilities for overseeing or monitoring specific environmental impacts within the flows of materials, the range of contributory economic/policy systems exerting pressures on the different options, key environmental concerns arising from different components of the fuel stream, transport options and their related environmental and social impacts, and so on. Scoping follows on logically from problem and goal de-

finition and will draw o n the issues raised during the consultation process. In this way, the scoping exercise establishes initially the case-specific environmental frame of reference and objectives and the social channels through which the processes are organised, controlled and acted on. SELCA scoping may reveal environmental concerns and impact routes which are usually considered outside the compass of conventional, site-specific environmental assessments. Exam- ples from our own research include concerns over medical wastes in the community (and the lack of research and monitoring of these) and the accumulation of secondary or additional industrial services at industrial plants, to which we return below. The initial results of the scoping exercise can bc publicised through tenants' and residents' associations, Chambers of Commerce, business, trade, employee and environmental organisations, for example, as well as relevant public news and information media. This will provide a range of alternative information sources and encourage wider appraisal of proposals and options.

3.3 Inventory/Data analysis

This step involves the collection and interpretation of the main data on the different options generated during the consultation process. ELCA invcutory analysis quantifies the mass and energy inputs/outputs from the total life cycles of the fuel streams. The quantitative information is provided in the form of an invcntory table which includes raw materials inputs, emissions to air and water, rcsidues, products and by-products, and transport, and so on. SLCA data analysis identifies the important controls over, organisation of and actions in the life cycles of the fuel streams. The qualitative information provided through this assessment is orga,lised as a reference grid identifying the social channels through which the different process options operate. This will include information on the classification of materials, the means by which materials and inputs are acquired and routed, use of process components by different people and organisations in the fuel streams, and support for or resistance to specific process components, for example. There is a range of data collection and analysis methods available for use in SLCA research. The sociological research into the two fuel streams in our own research combined three basic social science methods. These are: �9 Interviews with personnel in formal management organisations. �9 Analysis of documents held by contributory organisations to the two

fuel streams. �9 Focus groups with people involved in and/or affected by the fuel

streams.

3.4 Impact/Process assessment

For ELCA, the 'burdens' form the basis of the assessment which evaluates the impacts the burdens have on the environment. Impact assessment involves three steps: classification, characterisation and valuation. Classification and characterisation of burdens are made within specific categories relating to depletion, pollution and impairment, for

234 Int. J. LCA 1 (4) 1996


example. Characterisation of burdens in each of these categories expresses the impact of each burden in comparable terms, based on their relative impact within the category. There are commonly used means for characterisation within different categories, such as: resource depletion relative to known reserves, CO 2 equivalent for global warming, relative carcinogenic impact, or SO 2 equivalent contribution to acid rain. For SLCA, the basis of the assessment consists in identifying the key actions in, controls over and organisation of the fuel stream components. The flows of materials in the fuel- energy systems are described in terms of the channelling of resources, benefits and burdens through networks of goods and services by transactions or exchanges of values and responsibilities. The channelling process is important in the organisation of environmental impacts and occurs through the interaction of multiple, overlapping co-systems.

3.5 Evaluation

The information generated by SELCA may be put to a number of different purposes with the consequence that the improvement evaluation may be stated in a number of ways. Evaluations may take the form of policy or strategy proposals relating to the organisation, regulation or operation of contributory systems, or may involve recommenda- tions relating to levels of responsibility for components of

SELCA Evaluat ion: Step 1

Table 2: From environmental burden to social process

the operational cycle. Alternatively, the evaluation may include suggestions for consultation, monitoring or research methods. Evaluation occurs in two analytical stages. First, the findings of the ELCA and the SLCA are constructed as two tables (-4 Table 2 and 3) for ease of reference. The second stage consists in identifying those points in the life cycle where the ELCA and the SLCA suggest interrelated outcomes. Sometimes, the ELCA and SLCA suggest divergent courses of action or expose contrasting issues of concern. We make further comment on these issues in evaluation and provide examples from our own research in section 4.

4 Co-ord ina t ion of Results (with examples f rom the fuel cycles study)

When all of the assessments are completed, comparisons of the ELCA and SLCA findings generate the first stage in the evaluation step, where the ELCA and SLCA results are laid out in the form of two tables (examples are provided as Ta- bles 2 and 3). Table 2 indicates the influences of identified hazards on the social channels specified during sociological scoping. Table 3 indicates the influences of identified social processes on the environmental burdens specified during environmental scoping. The second stage consists in identifying those points where the two research strategies suggest interrelated outcomes.

Environmental burden

resource depletion

Loxicity, noise, congestion, air quality

acid gases, global warming, ozone depletion

Variable

raw materials costs and availability; loss of diversity

health, nuisance, social disrup- tion

health, landquality, erosion, agricultural output

Influence

government (economic) policy, business practice, consumer demand

Community and resident action, facility operation

government (environment) policy, technological investment

Example of effect

employment and remuneration, working and living conditions, social investment

local authority priorities and spending, monitoring frameworks, divergent inter- ests in local environments

protection and repair costs, health investment

SELCA Evaluat ion Step 2: Interrelating Outcomes

Table 3: From social process to environmental burden

Social process

control

3rganisation

~ction

Variable

decision-making structure;

materials classification

task/service distribution;

cost/benefit distribution

use of process components;

support for~resistance to process components

Influence

process operating conditions; type and level of participation

composition and sources of materials

responsibilities for specific materials and processes

public/private gain/loss from process operation

quantities of materials used; specific distribution of uses

promotion/blocking of technical and planning developments;

Example of effect

workplace health impacts; end-of-pipe versus clean technology impacts

composition of emissions and depositions to landfill; transport burdens

circulation of controlled materials; aggre- gation/separation of hazards

siting/distribution of depositions; technological development or stasis

resource depletion; waste production

siting/distribution of facilities; choice of technologies

Int. J. LCA 1 (4)1996 235

Life Cycle Assessment 6th SETAC-Europe Meeting

We provide examples from our own research of convergent, divergent and contrasting results to illustrate the sig- nificance of these connections.

i. Convergent Results

Example 1

The analysis reported in our own research (see O'BRIEN, CLIFT& DOIG, 1 996a) suggests that the environmental burdens deriving from waste and (especially) coal as fuels are significantly altered by the amount and type of transportation involved. Transport policy, however, is in some disar- ray. On the one hand, local authorities and businesses are counselled to use alternatives to road, on the other, the road infrastructure continues to attract massive subsidies in comparison with alternative options. Similarly, the push to competitiveness in source supply means that transport- ing coals from around the globe to the UK, with environmental burdens consequently significantly higher than UK alternatives, makes good business sense whilst encouraging additional environmental burdens.

Example 2

The second example where SLCA and ELCA overlap refers to the ways that development plans can be blocked or de- flected not so much by community opposition as by politi- cal agenda-setting. The Waste to Energy (WTE) power plant in our study was designed as a combined heat and power (CHP) plant with a capacity to supply to 55MW of heat to the local community. As a CHP plant, the environmental burdens are significantly lower when the heating facility is in operation. However, the community heating system was never installed for a combination of reasons. For example, WTE attracts subsidies under NFFO for displac- ing 'non-renewable' energy resources and can sell its electricity at a price above that available to 'conventional' generating stations. The subsidy combines with more stringent regulations on landfill sites to make WTE economically more viable than it would otherwise have proven, irrespec- tive of the environmental impacts that arise from different organisations of its operation.

Example 3

A final example of converging results is the response of the power sector to an international directive on acid gas emissions. To fulfil the European Commission directive on the reduction of SO 2 emissions, the UK government drew up a national plan which allocated a limited allowance of SO 2 gas emission to the main power generation companies. In response to this, the power generation companies retro-fit- ted their largest coal burning plants with flue-gas desul- phurisation (FGD) units. As a result of this initiative, in combination with the competitive pricing pool system for purchasing electricity, the retro-fit power plants are used to a minimum in order for the company to stay within its SO~ allocation at the same time as minim(sing company costs~ as the FGD units produce more costly electricity than dirt- ier power stations. This is an example of 'clean-up' tech-

nology and strategy as opposed to 'clean' technology and strategy (CLIFf and LONGLEY, 1995).

it. Divergent Results

Example 4

There will be occasions when the ELCA and the SLCA result in divergent evaluations or where the ELCA or SLCA expose different analytical and practical issues. For example, our own research observed that new WTE schemes are regularly, and often bitterly, opposed by community groups and environmental organisations even though their environmental performance as energy-generation systems is as clean, if not cleaner, in a number of respects than conventional alternatives such as coal-fired energy-generation. Our research indicates that the opposition is, in part, a case of NIMBY - waste-generators are always in someone's back yard: they have to be in order to gain access to the fuel (municipal waste) that they burn.

iii. Contrasting Results

Example 5

The SLCA may raise issues that are outside the remit of the conventional EI.CA. For example, an industrial development such as the construction of a power station ()pens the way for the addition of ()tiler commercial and industrial services at the same location. An example is the construction of the s million air separation plant - tile first use of a new technology in the UK - alongside Eggborough power station in Yorkshire. The construction of the plant has generated some concern among Yorkshire communities who believe that additional environmental hazards will arise as a result of the venture. Communities are experi- enced and knowledgeable about cycles of industrial development and, however, objectively 'clean' or 'green' a system appears to be, it will, over time, accrue additional functions, services and components. A conventional ELCA will not include such cumulative effects in its assessment.

Example 6

Conversely, by its whole system approach, ELCA can pri- oritise environmental concerns in a system which would not be identified by a SLCA. For example, many community groups complain about dioxin emissions from combustion plants, though both the fuel cycle examples indicate that dioxins are clearly not the main concern for human- or eco-toxicity. Priority concerns for toxicity in the fuel cycles are from N O emissions from the combustion plants or burdens from other parts of the fuel cycles, such as leachates from certain landfill sites. Also, both fuel cycles have reduced acid emissions by scrubbing SO 2 emissions, but the ELCA strongly indicates that N O emxssions remain a large acid emission concern.

5 Conc lud ing C o m m e n t s

The above examples indicate that the SLCA and the ELCA will highlight important, though sometimes contrasting is-

236 Iot. J. LCA 1 {4) 1996

6 t h S E T A C - E u r o p e M e e t i n g L i f e C y c l e A s s e s s m e n t

sues. The combined SELCA is intended to bring together different aspects of sustainability to produce a more complete and comprehensive analysis of social, economic and industrial development. We do not claim to have solved all of the problems associated with the integration of social, technical and environmental factors in the process of LCA. Indeed, we recognise that LCAs currently are complicated analytical tools requiring large amounts of data and so- phisticated assessment techniques into which it remains very difficult to insert social considerations. Nonetheless, if sustainable development is understood as referring to the intersect ion of the technological , economic and social processes through which humans t ransform their environments then research that commits itself to developing the methodological capacity to address each of these simulta- neously will be increasingly necessary in the future. Our research represents a first step in that direction. Rather than proceeding as if there are not important disciplinary and analytical differences between approaches to environmental research and monitoring, we have attempted to use the differences productively in order to establish a framework in which social and natural scientists, engineers and tech- nologists can contr ibute collectively towards the goal of unders tand ing envi ronmenta l change and informing the policy community of the many complex dimensions along which action must be taken.

Acknowledgements The research reported here is based on a two-year study entitled 'An En- vironmental and Social Life Cycle Comparison of Coal and Waste as Fu- els'. We would like to thank the Economic and Social Research Council and the Engineering and Physical Science Research Council, UK, for their support for this project. We would also like to thank the editor and anonymous reviewer for assistance with and comments on an earlier draft of this paper. Note: Complete reports of the SELCA methodology (O'BRIEN et al., 1996b) and the project results (O'BRIEN et al., 1996a) are available from the Centre for Environmental Strategy, University of Surrey, Guildford, GU2 5XH, UK.

6 Re fe rences

CLI~, R. & LONGLEY, A.j. (1995): Clean Technology: An Introduction, Journal of Chemical Technology and Biotechnology 62:321-26

DoIG, A., ELLlSON, J. & O'BRIEN, M. (1994): Combining Social Science and Environmental Data in the Development of Life Cycle Assess- ment. Presentation to SETAC Conference on LCA Case Studies. Brussels, December

DOIG, a. & Et.LISON, J. (1995): Validating and Completing the Model: Integrating Social Science Data Collection Methods and Life Cy- cle Assessment. 5th SETAC-Europe Conference, Copenhagen, June

O'BI~tEN, M., CxJv'r, R. & Doi(;, A. (I 996a): Social and Environmental Life Cycle Assessment: Report of a Study. Guildford, The Univer- sity of Surrey

O'BRll'N, M., CI If:T, R. & Dole;, A. (I 996b): Social and Enviromnental I.ife Cycle Assessment: Principles and Practice. Guildford, The University of Surrey

Modelling Fate for LCA Anneke Wegener Sleeswijk, Reinout Heijungs

Centre of Environmental Science, P.O. Box 9518, NL-2300 RA Leiden, The Netherlands

Corresponding author: Anneke Wegener Sleeswijk (e-mail: [email protected])

A b s t r a c t

Until now, impact assessment within LCA has mainly focussed on the substance hazard for some impacts, whereas, for other impacts, substance fate is included in the assessment as well. The main goal of this paper is to define the position of fate modelling in LCIA, and to specify the requirements for a general LCA fate model. A pro- posal is made to clearly distinguish an impact-category independent fate analysis from a separate exposure analysis and an impact-category related impact analysis, and to use a global multimedia model as a modelling basis. This modelling basis might be supplemented with substance-specific models for a number of substances.

Keywords: Life cycle assessment; characterisation; impact assessment; impact categories; regional differentiation; multimedia modelling; fate modelling; intermedia transport; degradation

1 I n t r o d u c t i o n

Emissions of hazardous substances may lead to different env i ronmenta l impacts. In life cycle impact assessment

(LCIA), diverse types of impacts are clustered to a substan- tially-limited number of impact categories. The relation- ship between the magnitude of an emission and the magnitude of its contr ibut ion to one or more impact categories depends on a number of factors. Some of these factors are directly coupled to emissions. These factors, which include substance identi ty and quant i ty and emission compar t - ment , are covered by the LCA inventory analysis. Other factors are coupled to specific env i ronmen ta l impacts , which means that they differ per impact category. Impact- category related factors include substance hazard and environmental sensitivity. These factors are (or could be) the object of LCA characterisation. These last factors remind of toxicity assessment with respect to terminology, but they apply to other impact categories in an equivalent way. Two factors which are not directly coupled to either emissions or impact categories, bu t which play an impor tan t role with respect to their quant i ta t ive re la t ionship , are substance fate and environmental exposure. It should be noted that ' env i ronmenta l exposure ' is used here as a general term for the exposure of environmental entities, which are not necessarily organisms.

Int. J. LCA 1 (4) 237-240 (1996) �9 ecomed publishers, D-86899 Landsberg, Germany

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social and environmental life cycle assessment (selca)

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