Reaction mass of 3,5,6,6-tetramethyl-4-methyleneheptan-2-one and (E)-3,4,5,6,6-pentamethylhept-3-en-2-one

Short-term toxicity to aquatic invertebrates

Description of key information

An OECD TG 202 guideline study in compliance with GLP with aquatic invertebrates (Daphnia magna) is available for the test substance. Daphnids (20/concentration) were exposed to nominal concentrations ranging from 1.0, 2.2, 4.6 and 10 mg/L and solutions containing 22, 46 and 100% of the WSF prepared at a loading rate of 100 mg/L under static conditions for 48 hours. Exposure was performed in air-tight closed vessels in order to minimize the loss of the test substance due to evaporation. Samples for analytical confirmation of the exposure concentrations were taken at the start and at the end of the exposure. During the exposure period the measured concentration remained constant (93-95% of initial) with the exception of the lowest concentration, which was at the level of 141% of initial at the end of the test. Based on these results, the average exposure concentrations were calculated to be 0.63, 1.4, 2.7, 6.4, 13, 29 and 67 mg/L. No immobilisation was observed in the control and the lowest concentration during the test (0.63 mg/L). The percentage of immobile daphnids increased from 10% at 1.4 mg/L to 100% at 29 and 67 mg/L. The study met the acceptability criteria prescribed by the protocol and was considered valid. As the measured concentrations in the lowest test group deviated by more than 20%, the effect value was based on the mean measured concentrations. Based on these data, the 48-h EC50 value is determined to be 6.1 mg/L (95% C.L. is 4.6 to 8.9).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

6.1 mg/L