Indicators for human toxicity in Life Cycle Impact Assessment

The main objectives of this task group under SETAC-Europe’s Second Working Group on Life Cycle Impact Assessment (LCIA-WIA2) were to identify and discuss the suitability of toxicological impact measures for human health for use in characterization in LCIA. The current state of the art of defining health indicators in LCIA is summarized in this document, promising approaches are addressed in further detail under the two headings of potency and severity, and then the suitability of the approaches is discussed with the aid of selected criteria.

Toxicological potency factors are based on test data such as No Observed Effect Levels (NOEL). NOELs, and similar data, are determined in laboratory studies using rodents and are then extrapolated to more relevant human measures. Many examples also exist of measures and methods beyond potency-based indicators that attempt to account for differences in expected severity, as well as potency.

Quantitative severity-based indicators yield measures in terms of Years of Life Lost (YOLL), Disability Adjusted Life Years (DALY), Quality Adjusted Life Years (QALY) and other similar measures. DALYs and QALYs are examples of approaches that attempt to account for both years of life lost (mortality) and years of impaired life (morbidity).

Qualitative severity approaches tend to arrange potency-based indicators in categories, avoiding the need to quantitatively express differences in severity. Based on the proposed criteria and current state of the knowledge, toxicological potency indicators are pre-selected as a minimum default. Addressing accuracy and ensuring consistency, particularly when extrapolating data, are seen as some of the key issues that are beginning to be addressed in LCIA.

While associated approaches are still in their infancy, it is encouraged to take into account relative severity whenever possible using qualitative and/or quantitative approaches.