# A Social Life Cycle Assessment Framework for Additive Manufacturing Products
## 2 Theoretical Background
### SLCA According to UNEP/SETAC Guidelines  
The publication of the guidelines [5] and its complementary methodological sheets [22] was considered a cornerstone in SLCA development, giving practical guidance on how to conduct SLCA [23]. As a result, following their publication, the number of case studies applying this methodology in different products and organizations has exponentially increased [24]. Nowadays, SLCA is still being applied in several case studies and in different international projects, contributing to the improvement of the methodology.  
According to the UNEP/SETAC guidelines, the social impacts can be observed in five main stakeholder categories, as Worker, Local Community, Society, Value Chain Actors, and Consumer. These categories are clusters of stakeholders that are expected to have shared interests, due to their connection to the product under assessment. Each stakeholder category is associated with a number of subcategories, which are socially significant themes or attributes. The subcategories are classified according to stakeholder categories and are evaluated by means of inventory indicators. Several indicators may be used to assess each of the subcategories. Each inventory indicator explicitly defines the data to be collected. According to [5], inventory indicators can be described as specific definitions of the data sought, and they are considered the most direct evidence of the condition or result of what is intended to be measured. Inventory indicators can be quantitative, semi-quantitative, or qualitative. Some social impacts can be better captured using quantitative indicators, while others may be better captured by semi-quantitative or qualitative indicators. Thereby, the type of indicator to be used in the assessment depends on the goal of the study and the nature of the issue that is being addressed.  
Another aspect that can be considered in the characterization of the indicators is the direction of the impact. According to [25], indicators may have a positive or negative desired direction for sustainability, depending on the nature of the social impact being measured. Social impacts can directly affect the organization's stakeholders, either positively or negatively [21]. Thus, indicators with a positive desired direction for sustainability, such as employee work satisfaction or percentage of the workforce hired locally, are used to measure the social impacts that affect the stakeholders in a positive way [25]. On the other hand, the indicators with a negative desired direction for sustainability are used to measure the social impacts that negatively affect the stakeholders (e.g., the number of occupational accidents, the gender gap, child labor, etc.).  
The main source of social indicators are the UNEP/SETAC methodological sheets [22]. They provide a list of more than 100 inventory indicators to assess each subcategory. Moreover, they identify whether data are available in quantitative, semi-quantitative, or qualitative type and provide data sources for each indicator. In their research [26] identified and analyzed 141 papers to study trends,consistencies, and gaps in research on the SLCA indicators. The authors argue that researchers should select the minimum set of the most important social indicators to assess the stakeholders, based on empirical experience, instead of common sense, across all industry sectors.