Methyl 2,6,6-trimethylcyclohex-2-ene-1-carboxylate

Short-term toxicity to aquatic invertebrates

Description of key information

EC50 (invertebrates) = 23 mg/L (C.I. 19 - 29 mg/L), 48hour-freshwater, OECD TG 202, Wil Research B.V. 2015

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

23 mg/L

Additional information

The acute toxicity to Daphnia magna was carried out according to OECD 202 Daphnia sp., Acute Immobilisation Test and EU Method C.2 guidelines. A limit test was combined with a range-finding test with air-tight closed-vessels without headspace. Twenty Daphnia magna per test group (4 replicates, 5 daphnia per replicate vessel) were exposed to untreated control medium and to a concentration of 1.0, 10.0 and 100% of a 100 mg/L saturated solution in the limit test. No immobilisation was seen at 1.0 or 10% loading rates whereas 100% immobilisation at 100% saturated was observed. A final test was performed based on the results of a finding test. Twenty daphnids per group (5 per replicate, quadruplicate) were exposed to an untreated control and to 5.6, 11.3, 22.5, 45 and 90 mg/L in vessels closed airtight without a headspace. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test. Analysis of the samples taken during the final test showed that measured concentrations were in agreement with nominal throughout the exposure period (i.e. 84-99% of nominal). Therefore, endpoints were based on nominal concentrations. The responses recorded in this test allowed for reliable determination of an EC50, with 0, 5, 50, 90 and 100% immobilisation at 5.6, 11.3, 22.5, 45 and 90 mg/l, respectively. No significant effects on the mobility of daphnia magna were observed at 48 hours up to and including 22.5 mg/L (nominal), while an average of 90% immobile daphnia were observed at 45 mg/L (nominal). There was no significant variation in the results of the combined limit/range-finding test and there were no significant responses at lower concentrations, and test item concentrations were satisfactorily maintained during the course of the study. The study met the acceptability criteria. The 48h-EC50 was 23 mg/L (C.I. 19 and 29 mg/L) based on analytically confirmed nominal concentrations.