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Short-term toxicity to aquatic invertebrates

Description of key information

OECD Guideline 202, EU Method C.2, GLP, key study, validity 1:
48h-EC50 = 12.9 mg/L (95% CL: 11.7 - 14.2 mg/L). 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

12.9 mg/L

Additional information

To assess the short-term toxicity of the registered substance to aquatic invertebrates, a set of two data are available.

The first study (LPL, 2016) was assessed as the key study and was performed on the registered substance according to OECD Guideline 202 and EU Method C.2 with GLP statement. In this study, Daphnia magna were exposed to the test substance at the concentrations of 0 (control with dilution water only), 3.0, 6.5, 10, 15 and 20 mg/L for 48 hours, under closed semi-static conditions (four replicates per treatment; five daphnids per replicate). The concentrations of the test substance, represented by analytical monitoring of the main constituent, were determined by chemical analyses at the start (t=0h), at t=24h (new and old solutions) and at the end of the test (t=48h). According to the results of this study, the 48h-EC50 was determined at 12.9 mg/L (95% CL: 11.7 - 14.2 mg/L), based on analytically confirmed nominal concentrations (the test substance levels were found to be stable throughout the test).

The second data (KREATiS, 2015), assessed as a supporting data, is a QSAR. This QSAR used a calculation method to predict the acute toxicity of the registered substance, a multiconstituent mixture of known composition, to aquatic invertebrates Daphnia magna (48h-EL50 value). This calculation method predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following OECD Guideline 202 adapted for testing as a mixture using the WAF method. This method has previously been validated in an internal publication (Bicheral and Thomas, 2014; available in the Endpoint Study Record). This algorithm is based on a QSAR model (iSafeRat® Holistic HA-QSAR v1.4) which has been validated to be compliant with the OECD recommendations for QSAR modelling (OECD, 2004). The QSAR is based on validated data for a training set of 58 chemicals derived from 48h test on daphnids, for which the concentrations of the test item had been determined by chemical analyses over the test period. Based on the chemical structure of ketones and alcohols, constituents of the test substance are expected to fall on the MOA 1 regression line and they can attributed to the class of non-polar narcotic compounds (MOA 1). Further to this, the effect loading rate of the WAF is determined by using a series of calculation steps using phase equilibrium thermodynamics and excluding the non-bioavailable fraction. The 48h-EL50 value based on mobility was determined to be 8.3 mg/L. This QSAR result supports the key study performed on the same substance with an EC50 value which is very similar but slightly more conservative, validating the model for use with this substance.

In conclusion, according to the key experimental study (LPL, 2015), the 48h-EC50 value on Daphnia magna is 12.9 mg/L (95% CL: 11.7 - 14.2 mg/L).