Butanoic acid, 3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-indenyl ester

Short-term toxicity to fish

Description of key information

The acute toxicity of Cyclobutanate towards Oncorhynchus mykiss was investigated according to OECD TG 203 under GLP. Fish were exposed to time-weighted average mean measured concentrations of 0.85, 1.4, 2.7, 4.9 and 11.0 mg/l and observed for 96 hours in a semi-static test setup. The test material solutions were prepared by stirring an excess (100 mg/l) of test material in dechlorinated tap water for a period of 48 hours prior to removing any undissolved test material by filtration (0.2 µm). This "saturated" solution was then further diluted, as necessary, to provide the remaining test groups.

Sub-lethal effects of exposure were observed at the time-weighted mean measured test concentrations of 2.7, 4.9 and 11.0 mg/1. At the time-weighted mean measured test concentration of 4.9 mg/1 between 24 and 48 hours 7 fish were observed to be moribund. At the time-weighted mean measured test concentration of 11.0 mg/1 after 1.5 hours all 10 fish were observed to be moribund. A steep dose-response curve was visible.

A decline in measured test concentrations was shown despite the use of sealed vessels with minimal headspace and no aeration in an attempt to minimise losses due to the volatile nature of the test material. Given the decline in the measured test concentrations (10 -70% loss was seen in 24 hours) it was considered justifiable to base the results of the definitive test on the time-weighted mean measured test concentrations in order to give a "worst case" analysis of the data. The 96-Hour LC50 based on the time-weighted mean measured test concentrations was 3.6 mg/1 with 95% confidence limits of 2.7- 4.9 mg/1 (concentrations resulting in 0% and 100% mortality respectively).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

3.6 mg/L