Gobierno de Gustavo Noboa Bejarano (22 de Enero del 2000-15 de enero

In some cases, the above mentioned approach is not possible, or is too elaborate. This can be illustrated by the case of chlorine compounds et 1993; Tukker et 1994), in which there were two problems. In the first place, there were some 100 different compounds, strongly connected within the economic system, included in the analysis. It was impossible to trace the environmental fate of all of those; therefore, an evaluation on the emission level was preferred. In the second place, the potential environmental impacts of these compounds vary widely, which means that it was not possible to find one term to express them that would cover all relevant aspects. The analysis of the economic flows was performed in kg in order to be able to draw mass balances, but kg Cl does not provide adequate information regarding environmental risks if Cl could refer to chloride, dioxins, CFCs, or PVC. Therefore, the emissions of the various chlorine compounds were translated into problem contribution equivalency factors, borrowed from the product impact assessment et 1992). These factors refer to specific environmental problems, such as global warming, ozone layer depletion, toxicity, etc. Every emission was translated into four (Kleijn et 1993) or eight (Tukker et 1994) values, thus reducing hundreds of separate emissions into 4 or 8 totals respectively. Changes in regime thus are translated into changes in the problem-causing potential of the total chlorine chain. Within the chlorine chain, the contribution of the various sub-chains, separate processes or process clusters, or compounds specific to the problem potentials can be identified. This approach clearly has some limitations: by translating emissions into problem contribution potentials, information with regard to space and time is lost. No comments can be made on whether some emission will actually lead to a transgression of concentration limits in a specific region. Thus, the analysis is purely comparative and not absolute. In the case of chlorine, the advantages of being able to analyze the chain as a whole clearly outweigh the unavoidable concurrent information loss.

This approach can also be taken with regard to other compounds. In a case study on six heavy metals in the Netherlands et 1995), the inflow into the agricultural soil was multiplied by its human and eco-toxicity equivalency factor from the LCA impact assessment Figure 4.1 shows the results. This led to the somewhat surprising conclusion that the top scorer for ecotoxicity is zinc by a large margin, followed by copper. For human toxicity the

The equivalency factors out of the LCA guide (Heijungs et 1992) contain an element the toxicity of the substance and a somewhat crude and incomplete element of the environmental Currently, there are ongoing on how to improve fate element in the factors for

highest score, as might be expected, is due to cadmium. In this case, the approach of confronting flows with environmental standards is preferable, since the same object is served with no information loss regarding space and time, and a relative as well as an absolute evaluation is possible. The results of both approaches should point in the same direction, provided the environmental are derived from the hazardous qualities of the substances. However, if we compare the two approaches for the group of six (see Figure this does not appear to be the case. The approach including standards shows only slight differences for the metals, and the largest reduction is demanded for copper, cadmium and mercury; the last one hardly scoring at all on the potentials for either ecotoxicity or human toxicity. At present, it is not clear how this marked difference can be explained. The most likely explanation is that the reduction targets for environmental policy have not been deducted in a direct manner from toxicity data and the current flows to agricultural soils, or that they have been "polluted" by other considerations, such as feasibility.

It can be concluded that, with regard to the environmental flows, more detailed information can be obtained from the overview with the help of additional information regarding the harmful qualities of the substance. By introducing environmental standards, either related to concentrations (stock) or emissions the flows and stocks out of the SFA overview can be translated into transgressions. Another possibility is the use of problem contribution potentials borrowed from the product LCA impact assessment. This provides possibilities to comprise large groups of substances into one analysis. This last procedure however also has its drawbacks: specifying the actual problems occurring within the region is not possible.

Figure 4.1 Evaluation of environmental flows by confrontation with policy targets or with LCA equivalency factors (4.1b)

4. la Transgression of policy targets for the input of metals in agricultural soils in The Netherlands in 1990. Actual input divided by target input. From: et

1995.

target = 1

Relative toxic potential of the accumulation of six metals in agricultural soils in The Netherlands in 1990. For human toxicity and ecotoxicity, relative to the highest score, which is set to 1. From: Annema et 1995; Heijungs et 1992.

4.4 Indicators for integrated chain management

4.4.1 Introduction

In 4.3, possibilities for evaluating the environmental flows with the help of environmental standards have been described. For the economic substance flows, however, no such approach is possible. There are no standards, nor can they be imagined, since flows and stocks do not cause any problems as long as they are locked within the economic system. However, it would certainly be useful to be able to comment on the economic substance flows as well, as the instigators for the environmental flows. This could then serve either as an early warning, or as a recommendation for environmental policy. After all, in order to solve the environmental problems, it is the economic flows that must be influenced. In this section, the definition of indicators for an integrated substance chain management as a part of the "interpretation" step of the SFA framework is the subject. Extra attention is given to the economic substance flows. Indicators play an important role in the interpretation of environmental data for environmental policy. The general idea is, to aggregate the rather large and ungainly lot of data into a limited set of measures relevant for environmental policy. The concept of "indicator" is not strictly defined, and in practice many widely different things may serve as indicators. A general demand made of indicators seems to be that they are easier to measure than the things they indicate. Other general requirements concern their possibility to be used for monitoring the success of environmental policy, their ability to be understood by non-scientists, and their appealing qualities.

Several attempts have been made towards a classification of indicators. The OECD for example distinguishes, along the chain of causality, state, pressure and response indicators (OECD, 1993a). The state indicators provide direct information on the state of the environment, mostly referring to ecosystems and the availability of natural resources. The pressure indicators comment on the direct (emissions) and indirect (societal) causes which therefore may have an early warning function. For example, the "policy performance indicators", developed by Adriaanse (1993) provide measures by which the development of certain environmental problems can be followed through time. Other examples, referring more to societal causes, are economic indicators such as the GNP (growth) or the population size (growth). The response indicators measure societal activities to combat the environmental problems, for example, the number of discarded bottles taken to the bottle bank. The classification made by Bakkes et al. (1994) closely corresponds to the OECD classification, but explicit attention is demanded in addition for problem-shifting to other regions.

In some sources, a difference is made between indicators and indices: an indicator is a single parameter variable, that is indicative of other variables as well, while an index is constructed out of more than one variable (OECD, 1993b). Opschoor & Reijnders (1991) speak of selections ("typical" or "representative" variables) vs. aggregates (transformations of underlying variables), corresponding roughly with the "indicator" vs "index" classification.

The indicators in this chapter are meant to provide information with regard to the substance's flows and stocks, relevant for environmental policy. In this case, "environmental policy" can be narrowed down to an integrated substance chain management policy. Substance chain indicators must be constructed in such a way that they provide:

a measure for the state of the stocks and flows of a substance on a given moment in time early warning for future problems

information on the influence of policy measures