Propanoic acid, 2-hydroxy-, (1R,2S,5R)-5-methyl-2-(1-methylethyl)cyclohexyl ester, (2S)-

Short-term toxicity to fish

Description of key information

The substance menthyl lactate was moderately toxic to the freshwater fish Danio rerio in an acute study over 96 hours.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

22 mg/L

Additional information

A study on the acute toxicity of menthyl lactate to the zebra fish (Danio rerio) was performed under static conditions over a period of 96 hours. The substance was undergoing hydrolysis under the test conditions. The main metabolite of hydrolysis was L-menthol. Due to the observed hydrolysis of the test substance, nominal concentrations were confirmed by gas chromatography analysis at the start of the experiment and at 24-hour intervals thereafter. All effects were based on measured concentrations of menthyl lactate and its hydrolysis product L-menthol. A hundred percent mortality was observed with a mean measured concentration of 32.9 mg/L over the first 24 hours. This was used as the LC100 in the calculations. No mortality occurred over the full testing period of 96 hours at an initially measured test concentration of 14.7 mg/L. This concentration was used as the LC0 value in the calculation. The LC50 value was approximated by calculating the geometric mean of the LC0 and LC100 values giving a LC50 value over a period of 96 hours of 22 mg/L. This value was used in the hazard assessment for the aquatic environment. Since no marine toxicity tests are available, the data generated with freshwater species were also used for the hazard assessment for the marine aquatic environment. The LC50 value for menthyl lactate is slightly above the LC50 value of its major breakdown product in water - L-menthol - which produced a LC50 value of 15.6 mg/L in an acute toxicity study with zebra fish over a period of 96 hours.