Cyclohexanamine, 4,4'-methylenebis[N-(1-methylpropyl)-

Toxicity to microorganisms

Description of key information

Toxicity to micro-organisms as per Activated Sludge Respiration Inhibition test OECD 209 (2010): 
3 hr EC50: 160 mg/l
3 hr EC10: 42 mg/l

Key value for chemical safety assessment

EC50 for microorganisms:

160 mg/L

EC10 or NOEC for microorganisms:

42 mg/L

Additional information

The Activated Sludge Respiration Inhibition test (Carbon and Ammonium Oxidation), in compliance with principles of GLP and OECD guideline No. 209, 2010, was conducted to determine the effects of the test substance (Trade name: Clearlink-1000) on micro-organisms. There were no deviations from standard operating procedures that affected the integrity of the study. So this study was considered as reliable with no restrictions and hence its result was used as a key value for hazard assessment.

Under the conditions of the above study, a statistically significant inhibitory effect of the test substance on aerobic waste water (activated sludge) bacteria was observed at all loading rates tested, ranging from 11% inhibition at the lowest loading rate (46 mg/l) to 99% inhibition at the highest loading rate (1000 mg/l). EC50 was determined to be 160 mg/l with 95 % confidence interval of 97-250 mg/l and EC10 was determined to be 42 mg/l with confidence interval of 25-70 mg/l.

One more study was conducted in accordance with Good Laboratory Practice (US-EPA FIFRA 40 CFR 160 and 40 CFR 792). This study was performed according to OECD guideline 209. However, the results were regarded as unreliable because the depletion of oxygen was measured at times from 0 to 60 minutes after removing the activated sludge from aeration. The dissolved oxygen depletion rate was calculated using the 60 minute concentration, at which the DO level was 0.4 mg/L. The guideline recommends that dissolved oxygen concentration should not be < 2 mg/L at the end of the measurement period. Therefore, it might be that actively respiring bacteria, at a concentration required by the OECD 209 method, could not show the results displayed in this report. Based on these facts, the study was chosen to be a supporting study.

On the basis of key study, it can be concluded that the test substance is toxic to micro-organisms.