2-tert-pentylcyclohexyl acetate

Toxicity to aquatic algae and cyanobacteria

Description of key information

The toxicity to aquatic algae is based on read-across from the close structural analogue Verdox (CAS# 20298-69-5). The 72 -h ErC50 and NOErC values are converted to Coniferan and are 4.0 mg/L and 0.54 mg/L, respectively.

Key value for chemical safety assessment

EC50 for freshwater algae:

4 mg/L

EC10 or NOEC for freshwater algae:

0.54 mg/L

Additional information

For the read-across source chemical Verdox the effect on the growth of aquatic algae was determined in a GLP-compliant OECD Guideline 201 study. Green algae (Desmodesmus subspicatus) with an initial cell concentration of 4E+03 cells/mL) were exposed for 72 hours to nominal concentrations of 1.75, 3.5, 7.0, 14, and 27 mg/L Verdox (3 replicates per concentration) and a control (6 replicates). Inhibition of algal growth rate and biomass (as yield) were monitored and all cultures were inspected microscopically at 72 hours. Samples of the test solutions were taken 0 and 72 hours and analysed by gas chromatography (GC). As the measured concentrations declined over the 72-hour testing period, the geometric mean of measured concentrations was used for calculating effect concentrations. The final concentration were all below the LoQ. Both growth rate and yield were significantly reduced compared to controls (p<0.05) at the three highest test levels. Based on these reductions the 72- h ErC50 and the 72-h NOErC were determined to be 4.2 and 0.57 mg/L, respectively. These effect concentrations are over-conservative values, because the LoQ is driving these toxicity values. No attempt has been made to calculate more realistic values because for the enviromental risk characterisation the algae NOEC of 0.57 mg/l because will not be the key value for the PNEC derivation.