Local risks and global impacts considering plant-specific functions and constraints: a case study of metal parts cleaning

Background, aim, and scope To achieve sustainable development in industrial processes, attributed chemical risks as well as environmental impacts should be managed. Such non-monetary issues have been analyzed by scientific assessment methodologies such as various risk assessment (RA) and life cycle assessment (LCA) procedures. Local risks to be addressed in RA are microenvironments, including the workplace and neighborhood. Although a comprehensive interpretation of such risks is necessitated in industrial decision making, no practical method has been developed to interpret various types of risk with sufficient understandings of plant-specific functions and constraints. Because elaborate model-based approaches are inevitable for practical process development, actual case studies on chemical risks and detailed plant-specific functions and constraints should be performed. Manufacturing processes require that metal parts must be cleaned in preparation for surface treatments or the completion of metal processing. The significant amount of cleansing agents utilized in cleaning processes has become an issue in Japan. Almost all cleaning processes in Japan are carried out by small- and medium-sized enterprises (SMEs). Machinery processes have not been systematically analyzed in terms of chemical risks and, in addition, the environmental management skills of SMEs are generally far behind those of large enterprises. The objective of this study is to reveal the relationships between chemical risks and plant-specific conditions for a practical risk reduction carried out by industrial decision makers. For this purpose, we aimed at the analysis of such relationships in metal-cleaning processes. Through this analysis, the correlation between local risks and global impacts were discussed in terms of plant-specific conditions. Materials and methods Through several investigations on cleaning processes, plant-specific functions and constraints were determined with process data required for plant-specific RA and LCA. By plant-specific RA, workers' and neighbors' health risks of inhalational exposure to the utilized cleansing agents were evaluated as unit exposure amount [mg·kg −1 ·day −1 ] and total exposure amount [mg·day −1 ] in the workplace and neighborhood. As global environmental impacts, human health impacts were evaluated by LCA using disability-adjusted life years through the life cycle of process chemicals including cleansing agents and utilities. On the basis of e