Amides, C16-18, N-[3-(dimethylamino)propyl]

Biodegradation in water: screening tests

Description of key information

C16-18 DMAPA amidoamine is readily biodegradable under aerobic conditions and fulfilling the 10 day window criterion (> 60% biodegradation based on O2- consumption). OECD Guideline 301 F; Ready Biodegradability: Manometric Respirometry Test; GLP, test concentrations: 16 and 100 mg/L.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The biodegradation of C16-18 DMAPA amidoamine (100% a.i.) was investigated in a study conducted according to OECD Guideline 301 F, adopted 17th July 1992 (Ready Biodegradability: Manometric Respirometry Test) and EU Method C.4-D, December 1992, over a period of 28 days using activated sludge sampled from a sewage treatment plant mainly fed with municipal wastewater as inoculum. The biodegradation rate was determined by measurement of O2 consumption. Inoculum blank, toxicity control and procedural/functional control with the reference substance Sodium benzoate were performed. The test was performed with 16 and 100 mg/L test substance concentration. The functional control reached the pass level >60% after 14 d (91%).

The biodegradation of the test substance was 78% (at 16 mg/L) and 85% (at 100 mg /L) after 28 days. The 10-day window started at day two and three, respectively. The biodegradation within the 10-day-window was 69% and 77%, respectively.

In the toxicity control the biodegradation was found to be 80% after 14 days of incubation. Thus, the demanded threshold value of 25% is exceeded and the test item can be identified as not inhibitory to microorganisms.

100 mg test item correspond to 316 mg ThOD, which is clearly above the demanded value of at least 50-100 mg ThOD/L. Therefore, an additional assay with 16 mg test item (51 mg ThOD, therefore, still meeting the required concentration of 50-100 mg ThOD/L) was conducted. At a concentration of 16 mg/L, the test item obtained a biodegradation above 60% (78%) within the test duration.

In this test, C16-18 DMAPA amidoamine was readily biodegradable fulfilling the 10-d window criterion.

 

The ready biodegradation of the closely related read-across substance Stearic acid 3-(dimethylaminopropyl)amide was investigated in a study conducted according to OECD Guideline 301B (CO2 Evolution test) over a period of 28 days and using municipal non-adapted activated sludge as inoculum. Inoculum blank, toxicity control and procedural/functional control with the reference substance sodium benzoate were performed.

The adaptation phase of the functional control changed after 2 days into the degradation phase (degradation >/= 10 %). The course of the degradation was rapid and the functional control reached the pass level of 60 % within 7 days and a biodegradation of 86 % after 28 days. The validity criterion degradation >/= 60 % after 14 days is fulfilled.

The biodegradation of the test item is shown in comparison to the readily degradable functional control and the toxicity control. The mean 10 % level (beginning of biodegradation) was reached after 6 days and the mean 60 % pass level was reached in the 10-day window after 16 d. After 28 days a mean biodegradation of 88 % was reached.

In this test, Stearic acid 3-(dimethylaminopropyl)amide was readily biodegradable fulfilling the 10-d window criterion.

The results from a study according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) with C22-Trimethylammonium Chloride is enclosed to justify the read-across approach for sediment and terrestrial toxicity studies: The substance was shown to be readily and ultimately biodegradable in this test.