Reaction mass of (+-)-(1RS,2SR,5SR,7RS,8SR)-5-METHYLTRICYCLO[6.2.1.02,7]UNDECAN-4-ONE and (+-)-(1RS,2SR,5RS,7RS,8SR)-5-METHYLTRICYCLO[6.2.1.02,7]UNDECAN-4-ONE

Short-term toxicity to aquatic invertebrates

Description of key information

Read-across, OECD Guideline 202, GLP, key study, validity 2:
48h-EC50 = 20.3 mg/L (95% CL: 16.0 -25.6 mg/L). 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

20.3 mg/L

Additional information

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

The first study (ABC, 2000) was assessed as the key study and was performed on an analogue according to OECD Guideline 202 with GLP statement. This substance is considered adequate for read-across purposes. It's a mixture of two stereoisomers, the same stereoisomers presents in the registered substance but in inverse ratio. In this study, according to a range-finding test, the test substance was exposed to Daphnia magna at the concentrations of 6.25, 12.5, 25.0, 50.0 and 100 mg/L for 48 hours, under static conditions. The no-treatment control daphnids were exposed to dilution water only. The temperature remained between 19 and 22 °C during the test. The mean measured concentrations of test substance were 6.11, 12.1, 23.8, 48.0 and 96.6 mg/L, i.e., 95 to 98% of the targeted nominal concentrations. Therefore, the test substance was considered to be soluble and stable under test conditions. No immobilisation was observed for the daphnids in the control and 6.11 mg/L treatments. After 48 hours of exposure, immobilisation of Daphnia magna for the definitive test was 45, 40, 90 and 100 % at 12.1, 23.8, 48.0 and 96.6 mg/L. The calculated 48-hour EC50 value based on mean measured concentrations was 20.3 mg/L (95%-Confidence Limit: 16.0 - 25.6 mg/L).

The second data (KREATiS, 2015), assessed as a supporting data, is a QSAR. This QSAR prediction (iSafeRat holistic approach v1.3) was performed on the registered substance, to assess the acute toxicity of the substance to daphnids. This QSAR has been validated to be compliant with the OECD recommendations for QSAR modelling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following OECD Guideline 202. The immobility of the daphnids was determined using a validated QSAR for the Mode of Action in question, (MOA 1, non-polar narcosis). This QSAR is based on validated data for a training set of 58 chemicals derived from 48-hour tests on daphnids, for which the concentrations of the test substance had been determined by chemical analyses over the test period. The water solubility of the substance given as input was experimentally measured (380.4 mg/L). The substance falls within the applicability domain of the model. The 48h-EC50 based on mobility was determined to be 15.4 mg/L (95% CL: 14.09 -16.87 mg/L).

In conclusion, the QSAR result obtained on the registered substance supports the key study, performed on the read-across substance. Therefore, based on the key study (ABC, 2000), the 48h-EC50 value was considered to be 20.3 mg/L (95% CL: 16.0 -25.6 mg/L).