5H-Cyclopenta[h]quinazoline, 6,6a,7,8,9,9a-hexahydro-7,7,8,9,9-pentamethyl-

Toxicity to aquatic algae and cyanobacteria

Description of key information

The toxicity to aquatic algae was examined in a study according to OECD TG 201, and in compliance with GLP criteria (Harlan, 2014). In this study algae were exposed to nominal concentrations of 1, 3.2, 10, 32 and 100% saturated solution. Analysis of 3.2, 10, 32 and 100% saturated solutions showed measured concentrations of 0.24, 0.80, 2.3 and 7.4 mg/L. A decline in measured test concentration was observed at 24, 48, and 72 hours leading to measured test concentrations of ca. 0.10, 0.40, 1.5, and 5.5 mg/L after 72 hours (loss of ca 25-40%). Therefore, time-weighted average concentrations were determined to be 0.20, 0.69, 2.1, and 6.8 mg/L, and results expressed as such. Algal cell concentrations were determined at the start of the test and after 26, 45, and 72 hours exposure, and microscopic examination performed at the end of the test. All validity criteria were met.

No inhibition of growth rate was observed up to a nominal test concentration of 3.2 % of saturated, whereas at nominal test concentrations of 10, 32, and 100 % growth rate was inhibited by 9%, 24%, and 84%, respectively. Based on these findings the 72-h ErC50, ErC10, and NOErC values were determined to be 3.4 mg/L, 1.3 mg/L, and 0.2 mg/L, respectively, based on TWA test concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:

3.4 mg/L

EC10 or NOEC for freshwater algae:

1.3 mg/L