Social impact assessment in LCA using the Preston pathway

The purpose of the social Life Cycle Assessment (LCA) method is to predict the social impacts on people caused by the changes in the functioning of one product chain throughout its life cycle. Changes in health status are very important experiences for people. The aim of this paper is to build a pathway between changes in economic activity generated by the functioning of a product chain and the changes in health status of the population in the country where the economic activity takes place. Empirical and historical factors suggest that increased economic activity through growth in income leads to improvements in the health of a country's population. This empirical relationship is well known in economics as the Preston curve. Using this relationship, we design a pathway for social LCA impact assessment. This pathway may be used to explain or predict the potential impact caused by the modification of one product sector upon the health of a population. The Preston relationship usually is calculated for a cross section of countries. We assess whether the Preston relationship is valid when a single country is considered alone. Drawing from scientific literature regarding development, we define the context where the use of the Preston relationship is justified. We describe the general design of the Preston pathway, using a recalculated (panel based) relationship, and specify the conditions for its use. We apply it to the case of company B, a banana industry in Cameroon, for the period between 2010 and 2030. We highlight that the panel calculation of the Preston relationship remains significant when a country is considered alone. We suggest that the following conditions are required for the pathway to be used: (1) the activity is set within countries where the GDP per capita in purchasing power parity is less than $10,000 at the start of the period, (2) the assessed activity accounts for a significant part of the annual GDP and/or demonstrates obvious signs that it represents a huge stake in the country's economy, (3) the duration of the assessed activity is regular and long enough, and (4) the added value created by the activity is shared within the country. We found that the future activity of company B would improve the potential LEX of the entire population of Cameroon by 5 days over 20 years, based on 200,000 t of bananas exported annually (in comparison with no activity). When the four conditions for use are met, and provided results are interpreted by comparing them with other situations or countries, the recalculated panel-based relationship may be used to explain or predict a change in potential life expectancy generated by a change in economic activity. The Preston pathway may be useful for impact assessment in social LCA. The assessment is valid only when used for a comparative analysis and must be done within a multi-criteria framework. Complementary pathways therefore need to be designed. We suggest that the conditions for use and other research issues be discussed and fine-tuned further. Moreover, we welcome comments and criticisms.