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LCA and the Working Environment

5 Impact assessment

5.1 Introduction to Life Cycle Impact Assessment

According to ISO (ISO/FDIS 14042:(E), 1999), the purpose of Life Cycle Impact Assessment (LCIA) is "to assess a product system's life cycle inventory analysis (LCI) to better understand their environmental significance". LCIA can, for example, be used to

• Identify and assist the prioritisation of product system improvement opportunities
• Characterise or benchmark a product system and its unit processes over time
• Make relative comparisons among product systems based on selected category indicators, or
• Indicate environmental issues where other techniques can provide complementary environmental data and information useful to decision-makers.

Within this framework, the methodology for working environmental assessment can be seen as a possibility for broadening the perspectives of an LCA by including knowledge about some of the impacts that directly affect humans, i.e. the people working to produce the products that are being investigated in the LCA.

5.2 The elements in Life Cycle Impact Assessment

In general, LCIA can be divided into a number of steps:

• Selection of impact categories, category indicators and models
• Classification (Assignment of Life Cycle Inventory (LCI) results)
• Characterisation (Calculation of category indicator results)
• Optional elements and information
  • Normalisation (relative proportion of category indicators to a reference value)
  • Grouping
  • Weighting
  • Data quality assessment

In the following sections, the developed methodology is described in relation to these general steps.

5.3 Selection of impact categories, category indicators and models

5.3.1 Selection of impact categories

The following impact categories have been selected for inclusion in the assessment:

• Fatal accidents
• Total number of accidents
• Reported injuries, diseases and damages
  • Hearing damages
  • Cancer
  • Muscolo-sceletal disorders
  • Airway diseases (allergic)
  • Airway diseases (non-allergic)
  • Skin diseases
  • Psycho-social diseases
  • CNS function disorder

The basic statistical information gives the possibility of dividing the total number of accidents into a number of specific categories, e.g. sprains and wounds. The benefits from doing so is however offset by the amount of work necessary to compile and process the information, and the possibility is thus not utilised in the current methodology.

5.3.2 Category indicators

The developed methodology is more simple than the EDIP97 methodology in the impact assessment step, simply because the impacts have been related to specific materials and processes already at the inventory level.

In the methodology, the inventory results, the category indicators and the category endpoints are the same. This is an inherent feature of the methodology, the reason being that the basic information is collected and processed at the national system level.

This methodology is thus not strictly in accordance with the final draft ISO 14042 standard which prescribe impact assessment in the above steps (section 5.2). However, Udo de Haes et al. (1999) acknowledges that the choice of the indicator at endpoint level may open new possibilities for a science-based aggregation.

If the choice of indicator at endpoint level is regarded as a problem, it could theoretically solved by using the procedure in EDIP97, i.e. that exposure time is used to aggregate the impacts from different parts of the life cycle. The major requirement in doing so is that assumptions should be made regarding exposure time in different sectors.

This is probably not very difficult, but will introduce additional uncertainties as the assumptions must be based on whatever relevant and available information that can be found. Under all circumstances the only profit from doing so is that the methodology will become more in line with the ISO 14042 requirements. There will be no additional important information with respect to the working environment as the final results ideally (and hopefully also in practice) should be the same.

It should be remarked at this point, that one of the important ideas behind using exposure time as the aggregation factor in EDIP97 was to accommodate the different data formats in the sector and the process assessment methods. As the process assessment methodology is not included in the present methodology, this need no longer exists.

5.3.3 Models

The model chosen for data collection and -treatment is entirely based on precisely defined statistical information. As described in other sections, the chosen model has its limitations with respect to both precision and general requirements in the ISO standards. At the same time it should be recognised that the model gives the possibility of including new and relevant issues in an LCA, and the choice should primarily be regarded as a first step towards a more detailed assessment methodology.

5.3.4 Assignment of LCI results (Classification)

As described earlier, the LCI results are the same as both the category indicators and the category endpoints.

This is a logical consequence of the close relationship between the governmental demand for decision support regarding working environmental issues and the available statistics on working environmental impacts.

The difference between assessing working environmental impacts and environmental impacts can thus be seen as the result of a long tradition for governmental interest in the working environment (The Danish Labour Inspectorate was founded more than 100 years ago as opposed to the natural environment (the Danish EPA was founded less than 30 years ago). During this period of time, assessment of the working conditions have changed considerably and the management tools that can be used for data collection and handling have been focused on creating an overview at the sector level rather than establishing precise information for single companies.

It should be remarked that there is additional statistic material available, e.g. in the form of exposure measurements for a number of chemicals and processes. The measurements are however relatively old, and it will be very difficult to relate the measurements to the processes that are actually included in the system boundaries. The information may however be useful in the sensitivity analysis or in the interpretation of the results as it can be used to pinpoint some of the processes within an economic sector which have a high potential for causing the impacts in the category endpoints.

5.3.5 Classification of category indicator results (Characterisation)

The remarks given in the previous section also apply to the characterisation element in LCIA.

5.4 Normalisation

The aim of the normalisation step in EDIP is to give an overview of the relative importance of the single effect categories. This is done by relating the actual (calculated) impact to the average impact caused by a person in the relevant geographic area.

In the present methodology, the basis for the normalisation is easily identified as the total number of reported working environmental accidents and damages in Denmark, distributed evenly on the number of Danes in the same period of time. As for the other calculations, the normalisation factors in Table 5.1 have been calculated as a three-year average for 1995-1997.

The procedure is thus simple, using the total number of accidents and work-related diseases as reported to the Danish Labour Inspectorate and dividing with the number of inhabitants in Denmark.

Table 5.1 . Normalisation factors for working environmental impacts.

The normalisation reference or person equivalent can be interpreted in the way that if every Dane was working, one out of a hundred persons would experience an accident at work every year.

The normalisation reference for the working environment is comparable to the normalisation reference for other environmental impacts, e.g. the contribution of an average Dane to acidification is calculated by dividing the total Danish contribution to acidification with the number of inhabitants in Denmark.

When performing the normalisation step, i.e. using the person equivalent, it is possible to examine both how the working environment differs between products and how important the working environment is in comparison with the impacts in the natural environment.

In Table 5.1, another set of normalisation factors, "The worker equivalents", is found. This set of figures show the probability for an average worker of experiencing an accident or report a work-related disease in a year. The only difference between the two sets of factors is that the worker equivalent is calculated using the number of employed persons in Denmark. The worker equivalent is suggested for use in specific working environmental LCAs, where absolute figures may give more suitable information than when using the Danish population as the normalisation reference. It should however be stressed that when the worker equivalent is used in normalisation, comparisons with other effect categories can not be made.

5.5 Grouping

Grouping is according to ISO/FDIS 14042:(E) "assigning impact categories into one or more sets. It may involve sorting which is descriptive or ranking which is prioritising".

Grouping is an optional element in LCIA and is not included in the general EDIP methodology as described in EDIP97.

No efforts have been devoted to describe a grouping procedure for assessment of working environmental impacts in the present methodology.

Seen in view of a lacking weighting procedure (see section 5.6), the development of procedures for either grouping or weighting of working environmental impacts could provide useful information for decision-makers. At the moment, the results of the assessment are presented without any kind of prioritisation, and the decision-maker must therefore use (subjective) values in the interpretation.

5.6 Weighting

The normalisation procedure for the working environment gives information on which effects that will be most frequently observed in the life cycle of a product. However, the most frequently observed effects are not necessarily the most problematic, e.g. fatal accidents must be regarded as more serious than hearing damages.

To account for this, the general EDIP methodology introduces an optional impact assessment step, namely weighting. The weighting of the impacts in the natural environment is done by using political targets for reduction in emissions.

This is however only possible to a limited degree for the working environment as the only specified target is that the number of fatal accidents shall be reduced to zero before year 2005. In addition, the Danish minister of labour has identified a number of other impacts that are of special concern and therefore should be reduced or totally avoided by year 2005:

• Hearing damages
• Occupational exposure to carcinogenic substances and work-related damages to the central nervous system caused by exposure to solvents or heavy metals
• Injuries to children and adolescents at work
• Damages to health caused by psycho-social risk factors at work
• Sickness or serious annoyances caused by an unsatisfactory indoor climate
• Damages and injuries caused by lifting of heavy burdens or by monotonous repeated work

No specific goals have been specified for these impacts and it is also not possible to relate all the concerned impacts to the effect categories used in the methodology.

It is therefore suggested that the weighting step be excluded from the assessment of working environmental impacts for the moment being. As a consequence, when comparing impacts in the natural environment to impacts in the working environment, this should be done following the normalisation step.

5.6.1 Suggestion for future development

In future developments of the methodology, alternative weighting methodologies should be considered, e.g. weighting by using economic indicators.

One way of rating the injuries could be the "Injury table" issued by the Danish National Board of Industrial Injuries. The table is used to determine the size of the indemnity when a person suffers a compensation-eligible occupational injury. The table rates a wide variety of injuries in percent of full disablement and can therefore be used as a weighing tool.

However, there may be a problem with the difference in level of detail. The impact categories in the assessment is often less detailed than the "Injury table". An example is the impact category "Muscolo-sceletal disorders" which covers a wide range of injuries with different levels of seriousness that are rated differently in the injury table. Another example is the impact category "Hearing damages" which only includes reduction in hearing but which can render the victim 5 - 75 % disable according to the "Injury table".

This means that one either have to increase the level of detail in the impact categories or somehow make an average over the different rates in the injury table.

The data basis to make the impact categories more detailed is available and by studying what kind of injuries they consists of, it would be possible to use the "Injury table" as a weighing tool. The "Muscolo-sceletal disorders" category could thus be divided into the different types of accidents, which could be given a percent rate. Since the number of accidents of each type is known it would be possible to estimate a percentage rate for the impact category.

One last problem remains due to the fact that not all registered injuries are compensation-eligible. However, this would not shift the balance since the accidents that are not compensation-eligible are minor accidents that would not weigh as much as those which are compensation-eligible.

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Version 1.0 April 2004, © Danish Environmental Protection Agency