Evaluation of the integrated testing strategy for PNEC derivation under REACH

•A dataset of 124 substances with FELS tests and chronic studies on Daphnia has been gathered.•Correlation of acute and chronic sensitivity between fish and Daphnia.•Regulatory decision support to complement the integrated testing strategy (ITS) of the REACH guidance R.7b.•Evaluation of the physicochemical properties water solubility and Kow as descriptors for chronic fish testing.

Species sensitivity evaluation represents an approach to avoid chronic toxicity testing of aquatic vertebrates in accordance with the animal welfare concept of the EU chemicals regulation. In this study a data set of chemicals is analysed for relative species sensitivity between Daphnia and fish in chronic testing to evaluate under what condition chronic fish tests can be waived without underestimating the environmental hazard. Chronic fish toxicity is covered in 84% of the evaluated substances by the chronic invertebrate test and an assessment factor of 50. Thus, animal testing can be avoided in environmental hazard assessment for many chemicals. Moreover, it is shown that species sensitivity in chronic testing is associated with species sensitivity in acute testing. The more sensitive species in chronic testing is predicted with a high probability if a species is >5x more sensitive in acute testing. If substances are comparable or more toxic to Daphnia in acute testing than to fish chronic fish toxicity is covered by the chronic Daphnia test and an assessment factor of 50 in about 95% of the evaluated cases. To provide decision support for the regulation of chemicals a categorization scheme on relative sensitivity comparison is presented.