6-(2,4,4-trimethylcyclopentylidene)hexanal

Short-term toxicity to aquatic invertebrates

Description of key information

QSAR model, iSafeRat , key study, validity 1:

48h-EC50 = 0.34 mg/L (95% CL: 0.21 - 0.54 mg/L).

 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

0.34 mg/L

Additional information

One valide QSAR predictions and one disregarded experimental study are avaible to assess the short-term toxicity of the registered substance to aquatic invertebrates

A Quantitative Structure-Activity Relationship (QSAR) model was used to calculate the ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50) of the test item. This QSAR model has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following the Guideline for Testing of Chemicals No. 202, "Daphnia sp., Acute Immobilisation Test" (OECD, 2004), referenced as Method C.2 of Commission Regulation No. 440/2008 (European Commission, 2008). The criterion predicted was the EC50 (Median Effective Concentration), a statistically derived concentration which is expected to cause immobility in 50% of test animals within a period of 48 hours.

The test item falls within the applicability domain of the model and was therefore reliably predicted for its ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50). Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50) of the test item was predicted as 0.34 mg/L. 95% confidence interval (α = 0.05): 0.21 - 0.54 mg/L

A Study was performed according to OECD Guideline 202 with GLP statement, to determine the treatment concentrations liable to immobilize 50 % of the daphnids (EC50) after 24 and 48 h exposure of the test item to Daphnia magna, under semi-static conditions. The test temperature was 20 °C kept constant at ± 1 °C. Before definitive test, a 48 h range-finding test was conducted and the percent immobilization was 0, 0, 0, 0, 80, 100 and 100 % at 0.04, 0.20, 1.0, 5.0 and 25.0 mg a.i./L, respectively.

However, this study is not reliable due to high concentration of solvent used. Indeed, a large quantity of acetone was used as solvent in this study. Because of the potential for interaction with the test chemical resulting in an altered response in the test, solvent use should be restricted to situations where no other acceptable method of test solution preparation is available. The use of solvent is not the best method at the time being. Furthermore, solvents are generally not appropriate for multiconstituent substances, like the test substance (which is a mixture of isomers), where the use of the solvent can preferentially dissolve one or more components and thereby affect the toxicity. Then, the concentration/quantity of solvent used in the treatment solutions was 5 mL/L, corresponding to 3.95 g/L (with a density of 0.79), which is 50 times higher than the recommended maximum level of solvent (below 0.1 mL/L; OECD 23) and represent almost half of the EC50 of acetone (which was reported in the ECHA disseminated dossier at 8.8 g/L). Acetone is suspected to have affected the definitive results. Some solvent/substance interactions may have occurred in this study with this high concentration of acetone.

Under the experimental conditions, EC50-48 h (Daphnia magna) was determined as 0.29 mg/L based on geometric mean measured concentrations.