Reaction mass of N1,N1'-(methanediyldibenzene-4,1 -diyl)diaryldiamine and 2-{4-[(4-aminophenyl)amino]benzyl}-N4-(4-{4-[(4-aminophenyl)amino]benzyl}phenyl)aryldiamine

Endpoint summary

Description of key information

The key study determined that the test item attained 1 % biodegradation after 28 days and therefore cannot be considered to be readily biodegradable (OECD 301 B, EU Method C.4 -C and CSPP 835.3110 (Paragraph (m)). A supporting study showed that biodegradation of the test substance was 10.7% after 28 days and, based on the residue analysis, biodegradation of the test substance was 8.00% during the testing period (HJ/T 153-2004, OECD 301 C and EU Method C.4-F).

Additional information

Key study

GUIDELINE

A study was performed to assess the ready biodegradability of the test item in an aerobic aqueous medium. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No. 301B, "Ready Biodegradability; C02 Evolution Test" referenced as Method C.4-C of Commission Regulation (EC) No. 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph (m)).

 

METHODS

The test item, at a concentration of 10 mg carbon/L, was exposed to activated sewage sludge micro-organisms with mineral medium in sealed culture vessels in the dark at temperatures of between 18 to 24 °C for 28 days. Following the recommendations of the International Standards Organisation (ISO 1995), the test item was dissolved in an auxiliary solvent prior to being adsorbed onto a filter paper and subsequent dispersal in test media. Using this method the test item is evenly distributed throughout the test medium and the surface area of test item exposed to the test organisms is increased thereby increasing the potential for biodegradation. The biodegradation of the test item was assessed by the determination of carbon dioxide produced. Control solutions with inoculum and the reference item, sodium benzoate, together with a toxicity control were used for validation purposes.

 

RESULTS

The test item attained 1 % biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301B.

Supporting study

GUIDELINE

A ready biodegradation test was performed according to “The guidelines for the testing of chemicals" (HJ/T 153-2004), “The guidelines for the testing of chemicals. Degradation and Accumulation'’ (the 2nd edition) (Beijing: China Environment Press. 2013), Procedure 301 C of the ‘Guidelines for Testing of Chemicals’ of the OECD: “Modified MITI Test (I)” (1992) and EU Method C.4-F (Determination of the "Ready" Biodegradability - MITI Test).

 

METHODS

The purpose of the test was to evaluate the ready biodegradability of organic chemicals via a 28- day test. The test substance and micro-organisms not adapted to the test substance were added to aerobic, aqueous medium in BOD bottles. The Biochemical Oxygen Demand (BOD) and residual chemicals in BOD bottles was then measured during the 28-day period. Test solutions were prepared in an inorganic salts medium, inoculated with a number of microorganisms collected from 10 places in Nanjing city. During the test, the temperature was kept at 25 ± 1 °C and pH was kept at 7.07 to 7.38. The total oxygen uptake in the inoculum blank was 30.0 mg 02/L at the end of the test, not exceeding 60 mg 02/L. The progress of degradation was followed by the determination BOD in the “test” and “blank control” vessels. Degradation was expressed as the ratio of the biochemical oxygen demand (BOD) and the theoretical oxygen demand (ThOD) in order to evaluate the ready biodegradability of chemical substance. The ready degradation rate was also expressed as percentage of initial concentration of test substance, where the residue analysis of the test substance was performed at the end (28 d) of the test. Substances are considered to be “ready biodegradable” if the ready degradation rate is equal to or greater than 60% during the 28-day test period.

 

RESULTS

Biodegradation of the reference substance, sodium benzoate, reached 71.9% at 7 days (> 40%), and 83.6% at 14 days (> 65%). The difference of replicate values for inoculum blank and test, during the test, was both less than

20%. Biodegradation of inhibition control was 66.1% at 14 days (>25%), and oxygen consumption by the test substance was 37.6 mg 02/L (> 60% of inoculum blank), indicating that there was no inhibition effect to inoculum. Thus, the test was considered valid.

 

CONCLUSION

The BOD results showed that biodegradation of the test substance was 10.7% after 28 days. Based on the residue analysis, biodegradation of the test substance was 8.00% during the testing period.