1-acetyl-4-(3-dodecyl-2,5-dioxo-1-pyrrolidinyl)-2,2,6,6-tetramethylpiperidine

Endpoint summary

Description of key information

See section "Additional information" below!

Additional information

The submission substance is of low water solubility (<0.05 mg/L) and thus test solutions were either prepared for a limit test with concentrations above the water solubility of the test item or with auxiliary solvent at permitted concentrations according to the guidelines (elaborated for each study below). In a 96 hours study on the toxic effects of the submission substance on biomass production and growth rate of green algae, no adverse effects were observed at a nominal test concentration of 0.80 mg/L test item (corresponding to 0.011 mg/L TWA). Furthermore, in a reliable study on inhibition of activated sludge respirartion (RL2) at a concentration of nominal 1000 mg/L, the test item was not toxic to microorganisms.

In a short-term toxicity test (RL2) performed in fish with a limit concentration above the water solubility, the submission substance did not cause any mortality at an arithmetic mean measured test concentration of 0.50 mg/L.

A reliable long-term toxicity test (RL1) is available regarding the reproductive success of Daphnia magna. Immobilisation of the parental generation and negative effects on reproductive success occurred in test concentrations below the limit of water solubility of the test substance, i.e. the derived 21d-EC50 (reproduction, parental immobilisation) and 21d-NOEC (reproduction, parental immobilisation) were 0.0031 mg/L (TWA) and 0.0013 mg/L (TWA), respectively. In addition, in an available (not reliable, RL3) short-term toxicity study of daphnia magna, immobilisation was observed in concentrations slightly above to the water solubility of the test item, i.e. the 48h-EC10 was 0.067 mg/L. In conclusion, the long-term results showed that the submission substance was toxic to aquatic organisms at concentrations below the water solubility of the test substance, and Daphnia magna was the sensitive species.

 

Short-term toxicity to fish (RL2)

As the test item was of very low water solubility (<0.05 mg/L), methanol was used as solubilizing aid and a limit test was performed using a nominal concentration more than a factor of 10 above actual water solubility. The test was performed under flow-through conditions with analytical monitoring of test item concentration. Until the end of exposure, no mortality in Gold orf was observed (Leuciscus idus melanotus HECKEL) at the limit concentration, and the following effect concentrations were determined: 96h-LC50 (Gold orf, mortality) >0.50 mg/L (arithmetic mean measured); 96h-LC0 (Gold orf, mortality) >= 0.50 mg/L (arithmetic mean measured).

 

Short-term toxicity to Daphnia magna (two studies, RL3)

The two available studies on the acute toxicity of the test item on the mobility of Daphnia magna were not considered reliable because of inter alia missing analytical measurements. For one of the studies the determined nominal acute effect concentrations were: 24h-EC50 = 0.4 mg/L, 48h-EC50 = 0.27 mg/L and 48h-EC10 = 0.067 mg/L test item. These results were to some degree in line with acute immobilisation data of the preliminary test of the available Daphnia magna reproduction study (IUCLID entry section 6.1.4). However, determined acute effect concentrations must be treated with caution.

 

Long-term toxicity to Daphnia magna (RL1)

Exposure of Daphnia magna to an aqueous dispersion of the test material resulted in a significant prolonged mortality effect at the highest test concentration of 0.0096 mg/L resulting in 100% mortality by day 9. Significant mortality was also observed at 0.0033 mg/L test concentration resulting in 20% mortality by day 16 and 60% mortality on day 21. The following effect concentrations were determined: 21d-EC50 (Daphnia magna, reproduction/parental immobilisation) = 0.0031 mg/L (TWA); 21d-NOEC (Daphnia magna, reproduction/parental immobilisation) = 0.0013 mg/L (TWA).

 

Toxicity to aquatic algae (RL1)

No negative effects of the test item on both, growth rate and biomass production of green algae were observed after 72 hours of exposure. Scenedesmus subspicatus was exposed to an aqueous solution of the test material at a limit concentration of nominal 0.80 mg/L. As the test item was of low water solubility (<0.05 mg/L, see IUCLID section 4), auxiliary solvent was used at its permitted concentration. Following effect concentrations were derived: 72h-EbC50 (biomass) > 0.011 mg/L (TWA); 72h-ErC50 (growth rate) > 0.011 mg/L(TWA); 72h-NOEC (biomass, growth rate) >= 0.011 mg/L (TWA).

 

Toxicity to microorganisms (RL2)

With regard to the low water solubility of the test item (<0.05 mg/L, see IUCLID section 4), a limit test was performed using a nominal test concentration of 1000 mg/L test item. The results of the study showed that the test item did not cause any negative effect on the respiration rate of microorganisms. The following effect concentrations were determined: 3h-EC50 > 1000 mg/L (nominal); 3h-NOEC >= 1000 mg/L (nominal).