Aiding alternatives assessment with an uncertainty-tolerant hazard scoring method

Area of Science:

• Environmental Science
• Toxicology
• Risk Assessment

Background:

• Chemical alternatives assessment is complex, involving numerous toxicological variables and data gaps, making it difficult for non-experts to interpret.
• Existing methods often lack a single, clear score and do not adequately quantify uncertainty, hindering practical decision-making for business leaders and policymakers.
• Balancing chemical hazard with product functionality and acknowledging uncertainty are critical for selecting safer alternatives.

Purpose of the Study:

• To develop a transparent and reproducible single-score system for chemical alternatives assessment that accounts for uncertainty.
• To translate multiple hazard endpoints into a simple numeric score, facilitating easier comprehension and decision-making.
• To aid in comparing product alternatives by providing both hazard and product functionality scores with quantified uncertainty.

Main Methods:

• Developed a novel scoring method inspired by Clean Production Action's GreenScreen but with a distinct score aggregation approach.
• Translated eighteen hazard endpoints into a single numeric score, incorporating quantified uncertainty.
• Applied the method in a case study assessing alternatives to spray polyurethane foam insulation containing methylene diphenyl diisocyanate (MDI).

Main Results:

• The new hazard scoring method successfully identified trade-offs between different chemical alternatives.
• The system provided finer resolution and differentiation compared to the GreenScreen Benchmarking system.
• Sensitivity analysis indicated that uncertainty from data gaps had a greater impact on alternative rankings than weighting schemes.

Conclusions:

• The proposed single-score system simplifies chemical alternatives assessment, making complex toxicological data accessible for decision-making.
• Quantifying uncertainty in the final score provides crucial insights into the reliability of hazard data and the maturity of product development.
• The method offers a valuable tool for industries seeking to identify and adopt safer chemical alternatives, as demonstrated in the building materials case study.