Environmental assessment of chemicals: methods and application to a case study of organic solvents

Suitable environmental assessment tools are needed for the development of sustainable chemical products and processes. In this paper, three methods for the environmental assessment of chemicals with different focus, fields of application, and data requirements are presented. The first method aims to identify potential environmental, health and safety hazards in the early phases of chemical process design. The second approach is to calculate screening indicators for unwanted environmental exposure to chemicals in terms of persistence and spatial range. The third approach is to perform a full life-cycle assessment. The differences between the methods are discussed, first, on a theoretical basis and then within a case study of 13 solvents. The results of all three methods indicate that the use of chlorinated solvents should be avoided, while solvents such as methanol, isopropanol, toluene and xylene are less problematic. Moreover, there are results that are unique to each method: in addition to the chlorinated solvents, nitrobenzene has a potential for long-lasting and widespread exposure; concerning environmental, health and safety aspects, care should be taken with respect to formaldehyde, benzene, and acetic acid; according to the life-cycle assessment, energy use makes up for a large fraction of the impact for solvents such as aniline. In the case study, the three methods provide consistent results both in the overall environmental assessment of the chemicals and with regard to single aspects such as degradability or toxicity. Since not all aspects are considered in all methods, the methods also provide complementary results.