Reaction mass of 3,7-dimethyl-1-octyl propionate and citronellyl propionate

Toxicity to aquatic algae and cyanobacteria

Description of key information

In a 72-h toxicity study according to OECD 201 and in compliance with GLP, exponentially growing green algae (Raphidocelis subcapitata) were exposed to individually prepared WSFs. Exposure concentrations were verified by a validated method. In the range finder at 0.1 and 100 mg/l WSF the concentrations at t=1 were 0.0429 and 3.96 mg/l. After 72h these were decreased to 13 and 30%: 0.0056 and 1.2 mg/l, respectively. In the main test the loading rates were 0.32, 1.0, 3.2, 10, 32 and 100 mg/L at the start of the main test, measured concentrations were 0.016, 0.041, 0.65, 0.73, 0.98 and 1.2 mg/L. The verified concentrations are somewhat irregular showing a clear concentration increase at the three lower concentration, but the next two concentrations are rather close to each other. All but the two highest concentrations decreased to < 10% after 24h and were all below LOD after 72 hours except the highest. This is in contrast to the range finding. Therefore the dissipation in the main study was considered due to the need of verifying the analysis of the samples after 4 weeks of storage. Therefore the analytics are presenting lower concentrations than those where the algae are actually exposed to. In view of the toxicity being consistent up to initial measured concentration of 0.73 mg/l and this toxicity being highest after 24 h it was considered justified to derive the effect values on the initial measured concentrations: the 72h-ErC50 was >1.2 mg/L and the 72h-ErC10 was 0.61 mg/L (95% CI 0.44 to 0.70 mg/L).

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

0.61 mg/L