3-ethoxy-1,1,5-trimethylcyclohexane

Short-term toxicity to aquatic invertebrates

Description of key information

Two acute invertebrate studies exist for this test substance, the first a static, closed design, in vivo study following OECD 202 where a saturated stock was prepared (100 mg/L) by shaking for 1 hour to mix the test susbtance followed by phase separation (2 h) was allowed to occur and the aqueous phase followed by immediate testing. Substance anslysis was performed at T0 and at the end of the study in order to determine test solution concentrations. The 48 h EC50 was 5.7 mg/L based on measured values.

This study was considered valid with restrictions due to significant losses from the study (approximately 50% over the 48 hours) and a semi-static design would have led to reduced losses. Therefore, a QSAR model, similar to that used for the fish study, was also included to provide a reference for this substance. The test substance is within the applicability domain of this model and the QMRF and QPRF included in the RS. The 48 h EC50 was calculated at 2.7 mg/L, close to and slightly below the EC50 calculated from the in vivo daphnid study. On this basis, and considering that the substance appears to hydrolyse fairly rapidly the results are considered accurate and the 48 h EC50 of 2.7 mg/L for invertebrates will be used for C&L and risk assessment purposes.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

2.7 mg/L