The Chemistry Indicator represents the human and ecological toxicity impact created. This means the harm done by chemical substances to humans and the environment throughout the life cycle of the material, process or product. The Chemistry Indicator is measured in “units”. This unit of measurement is taken from the USEtox model, because the impact calculation is based on the USEtox characterization values.
The number of units is determined by the impact of the separate processes that make up material production. Each process has low, medium or high impacts assigned to them:
- Low: 2 Chemistry Units
- Medium: 4 Chemistry Units
- High: 6 Chemistry Units
The aggregated process impacts determine the material-level chemistry impacts.
The Chemistry Indicator MSI score can be analyzed in the same way as the MSI score for the other LCIA categories: a score of 10 is what an average material would score (this does not imply high or low impact).
More information on the methodology of the Chemistry Indicator can be found in the Appendix of the MSI methodology document on page 47.