3,7-dimethylocta-2,6-dienyl acetate

Toxicity to aquatic algae and cyanobacteria

Description of key information

The algae toxicity is derived from Geranyl acetate, which summary is presented below. The read across rationale is presented in the Aquatic toxicity endpoint summary. The accompanying files are also attached there.

Geranyl acetate and its algae toxicity

The toxicity to freshwater green algae was investigated in a study according to OECD TG 201, and in compliance with GLP criteria. In this study, fresh cultures of green algae (D. subspicatus) were exposed to nominal test concentrations of 0 (control), 1.0, 2.2, 4.6, 10, and 22 mg/L for 72 hours under continuous illumination. As the test item is poorly soluble, each of the test solutions was prepared separately (differential loading) by directly adding test item to test medium, and gently shaking for about one day. Nominal concentrations were analytically verified at the start and at the end of the test. Based on samples taken at the start of the test, measured concentrations were n.d., 0.171, 0.585, 1.608, 2.104, and 7.747 mg/L (17.2 to 35.2% of nominal). In all samples taken at the end of the 72-h test period, test substance could not be determined (i.e. below LOQ). Complete loss of test substance was verified in uninoculated samples for each concentration. Since measured concentrations deviated markedly from the nominal concentrations, and since the mean measured concentrations could not be calculated, the effect concentrations based on measured initial concentrations are used for evaluation of the test item (considered as the effect of the parent test item and all degradation products). Cell biomass was determined at 0, 24, 48 and 72 h by means of chlorophyll-a-fluorescence, and growth rates calculated. The test is valid. A statistically significant inhibition of growth rates was observed in the three highest test concentrations. At measured concentrations of 1.608, 2.104, and 7.747 mg/L, growth rate inhibitions were 16.0, 21.3, and 86.9%, respectively. Based on these findings, the 72-h ErC50 and 72-h ErC10 values were determined to be 3.72 mg/L and 1.19 mg/L, respectively. The 72-h NOErC was determined to be 0.585 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

3.72 mg/L

EC10 or NOEC for freshwater algae:

1.19 mg/L