Cyclopentaneacetic acid, 3-oxo-2-pentyl-, methyl ester, (1R,2S)-rel-

Toxicity to aquatic algae and cyanobacteria

Description of key information

Read-across, OECD Guideline 201, non-GLP, key study, validity 2:
72h-ErC50 growth rate (P. subcapitata) = 45.9 mg/L (nominal concentrations);
72h-NOECr growth rate (P. subcapitata) = 11.7 mg/L (nominal concentrations).

Key value for chemical safety assessment

EC50 for freshwater algae:

45.9 mg/L

EC10 or NOEC for freshwater algae:

11.7 mg/L

Additional information

To assess the toxicity of the registered substance, METHYL CIS-3-OXO-2-PENTYL-1-CYCLOPENTANE ACETATE, to aquatic algae, one valid study is available.

This non-GLP study (Hotaka, 1998), assessed as a key study, was performed on a read-across substance, METHYL 3-OXO-2-PENTYL-1-CYCLOPENTANE ACETATE (quality High Trans isomer), according to OECD Guideline 201 (1984). This read-across substance is a mixture of two diastereomers, approximately 10% cis- and 90% trans-diastereomers of which the cis-diastereomer corresponds to the registered substance.

Pseudokirchnerella subcapitata was exposed to solutions of the test substance at nominal concentrations of 4.0, 6.8, 11.7, 20.0, 34.2, 58.5 and 100 mg/L for 72 hours, under constant illumination and shaking at a temperature of 23±2°C. The test substance solutions were prepared from a stock solution of test material in HCO-40 (1000 mg/l) and from a HCO-40 stock solution (1000 mg/l) to maintain final HCO-40 concentrations at 100 mg/l in all test conditions. Analytical monitoring was not performed as not required by the test guideline followed (1984). However,the test substance is expected to be stable in the test solution: OECD TG 111, half-life pH 7 > 1 year (this was confirmed with the long-term toxicity study on Daphnia magna where nominal concentrations were relatively well maintained during static renewal conditions: 74 to 101% of nominal values), has been shown to be moderately soluble (> 500 mg/L) and was not considered volatile in the physico-chemical studies.

Samples of the algal populations were removed at 24, 48 and 72h and cell concentrations were determined for each control, solvent control and treatment groups. Potassium dichromate was used as positive control.

In terms of growth rate, exposure of Pseudokirchnerella subcapitata to the reference material, Potassium dichromate, gave an ErC50 (72 h) of 0.363 mg/L, a value in accordance with testing laboratory routine test results. In addition, exposure of Pseudokirchnerella subcapitata to the test substance gave an ErC50 (72 h) and a NOECr (72h) values of 45.9 mg/L and 11.7 mg/L, respectively.

This supporting substance is considered adequate for read-across purposes based on similar physico-chemical properties and the same ready biodegradability potential between the registered substance and the analogue material used.