Regarding calculation of new characterization factors (CFs) and differentiation between acute and chronic effect data (EC50-data): As I have understood, there is no scientific consensus regarding how to differentiate between acute and chronic ecotoxicological tests (EC50-tests), needed for calculation of new CFs in USEtox.
The User Manual does not give much guideline with regard to this and tests I've done show that various methods used for differentiating between acute and chronic tests may greatly influence the resulting CFs!
Do you have any suggestion how to differentiate between acute and chronic ecotoxicological tests? For example: always follow indications in databases from which data is collected, or strictly apply a differentiation method based on test duration? How to do when neither is stated?
It is recommended to use chronic toxicity data by the USEtox team as long as they represent measured EC50 values, since this represents realistic conditions (see Rosenbaum et al., 2008). However, if a study is based on a comparison of chemicals for which only acute data are available, acute data can equally well be applied, since an extrapolation factor would be equal for all chemicals.
Further information on estimation of input data needed including route-to-route and acute-to-chronic extrapolations can be found in Rosenbaum et al. (2011).