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

Biodegradation

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).

Adsorption coefficient

The adsorption coefficient of the test item was determined to be in the range 42.8 to > 4.27 x 10E05 with a Log10 Pow of 1.63 to > 5.63 (OECD 121 and EU Method C.19).

Additional information

Biodegradation

A key 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)).

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.

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.

In a supporting study, the 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), and 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).

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 initialconcentration 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.

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. 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.

Adsorption / desorption coefficient (Koc)

The determination was carried out using the HPLC screening method, designed to be compatible with Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001. The test utilised a High Performance Liquid Chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used. The adsorption coefficient of the test item was determined to be in the range 42.8 to > 4.27 x 10E05 with a Log10 Pow of 1.63 to > 5.63.