2-tert-pentylcyclohexyl acetate

Short-term toxicity to fish

Description of key information

The short-term toxicity to fish is assessed based on read-across from the close structural analogue Verdox (CAS# 20298-69-5) and the LC50 value determined at 5.3 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

5.3 mg/L

Additional information

The short-term fish toxicity of Coniferan is assessed with information from Verdox. The short-term fish toxicity is summarised below. The read across justification is presented at the Aquatic toxicity Endpoint summary.

Verdox short-term fish toxicity: For the analogue source substance Verdox the acute toxicity to fish was determined in a GLP-compliant EU Acute toxicity to fish (C.1). In this semi-static test, groups of 10 zebra fish (Danio rerio) were exposed for 96 hours to nominal test concentrations of 0, 7.8, 11 and 16 mg/L of the test substance in ISO-water. Samples of the test solutions were taken at the start of the test and after each 24-hour renewal and analysed by gas chromatography (GC).

Measured concentrations at t=0 were already much lower than the nominal concentration and at 24 h the test substance decreased to ca 25 to 30% of the initial measured concentration.At initial measured concentration of 6 mg/l (and 2.6 mg/l after 24 h): 20% mortality was seen (at nominal concentration of 11 mg/l at 72h exposure). At these concentrations also lethargic effects were seen in fish. At initial measured concentration of 13 mg/l (and 5 mg/l after 24 h): 100% mortality was seen (at nominal concentration of 16 mg/l and 72h exposure).At initial measured concentrations up to 6 mg/l no mortality was observed and also not a 2.6 mg/l when measured at 24h (nominal concentration was 11 mg/l). 100% mortality was observed at 13.2 mg/l.

The test result can be interpreted such that concentrations of 13 - 5 mg/l cause 100% mortality. These values are around the water solubility of the test substance. Therefore the toxicity may partly due to physical effects, because of the effects seen at the water solubility and the all or nothing effect as well as the lethargic behavior before the fish were dying.  The absence of mortality is seen at maximum concentrations of 6 -2.6 mg/l.

Because no mortality is seen at 6 mg/l initial measured concentration and at 2.6 mg/l finally measured concentrations and 100% mortality at 13 mg/l initial measured and at 5 mg/l finally measured, it seems justified to calculate an LC50 being a geometric mean between 3.9 mg/ (root of 6 x 2.6 mg/l) and 8 mg/l (root of 13x5 mg/l) = 5.6 mg/l. Again this seems to be a worst case value because the physical effects cannot be excluded.