This paper compares available options for the aquatic ecotoxicological effect factor component in life cycle assessment (LCA). The effect factor is expressed here as the change in risk per unit change in cumulative exposure, ƒ´Effect/ƒ´Exposure. The comparison is restricted to approaches linked, implicitly as well as explicitly, to species sensitivity distributions (SSDs). This draws on recent insights for chemical mixtures and identifies the implications of different model choices. In spite of the many options, assumptions, and areas for further research, it is concluded that a single effect factor basis represents the best available practice for use in LCA at this time, ƒ´PAFms/ƒ´C = 0.5/HC50; where ƒ´PAFms is the change in the (Potentially Affected) Fraction (PAF) of species that experiences an Increase in exposure above a specified effect level, accounting for the presence of complex background mixtures (ms), ƒ´C is the change in cumulative exposure concentration of the chemical of interest, and HC50 is the median, chronic Hazardous Concentration for regional, multiple species systems. The resultant aquatic effect factors are risk-based and can be readily estimated for many chemicals using available methods, without the need to describe the entire SSDs and without the need for additional data. For example, the octanol-water partitioning coefficient provides a sufficient estimation basis for about 50% of existing chemicals that have a narcosis mode of action. This is also relevant in LCA for more chemicals that are at low concentrations in the environment; concentrations below biological thresholds at which more specific modes of action would be of relevance.
|Journal||Environmental Toxicology and Chemistry|
|Publication status||Published - 2004|
- Risk assessment
- Ecotoxicological indicators
- life cycle impact assessment