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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Biodegradation in water: screening tests:
The given test material 2,4-Diaminoazobenzene is determined to be readily biodegradable in water.

Biodegradation in water and sediment:
Estimated half life of test chemical 4(phenylazenyl)benzene-1,3-diamine in water was 60 days (1440 h) and in sediment estimated to be 541.66 days (1300 h).

Biodegradation in soil:
Biodegradation half-life of test substance 4-(Phenylazo)benzene-1,3-diamine in soil was estimated to be 120 days (2800 hrs).

Additional information

Biodegradation in water: screening tests:

Different experimental studies for the Biodegradation in water endpoint were reviewed for the test substance4-(phenylazo)benzene-1,3-diamine and are summarised below:

From peer reviewed journal (Eiichi Idaka et al;Bull. Environ. Contam. Toxicol.,1987), Biodegradation of the test chemical 2, 4-Diaminoazobenzene was studied. Soil samples were gathered from the draining trenches of the dyestuff works in the Hashima district. An enrichment culture was made for strainPseudomonas cepacia13NA and was included in the study as inoculumn. Three loopful of grown overnight culture was inoculated in 100 ml of medium in a 500 ml flask and cultivated on a rotary shaker (5 cm stroke, 200 rpm) at 37 deg. C. 100 ml of precultivated broth were used as inoculum for five 10 L flasks. The cells were harvested by centrifugation at 10000 rpm for 15 mins. The cells were washed twice with 0.03 M phosphate buffer, pH 6.8. The washed cells were suspended in 0.03 M phosphate buffer, pH 6.8 which contained the test compounds and incubated at 37 deg. C under static conditions for 24 hrs. The cultural fluid (25 L) was obtained from the washed cell incubation by centrifugation at I0,000 rpm for 15 min. The cultural fluid was adjusted to pH 12.0 with 1 N-NaOH and extracted 3 times in a separating funnel with CH2CI 2 in an amount equal to the cultural fluid by volume. The CH2Cl2 layer was washed with water and an aqueous solution saturated with NaCl, respectively, and then dehydrated with anhydrous Na2SO 4. After being filtered, the solution was concentrated in vacuo by a rotary evaporator. Preliminary identification of metabolites was made by thin layer chromatography (TLC) of authentic compounds. The concentrated samples were applied to a silica gel plate (2.5 x 7.5 cm; Merck's TLC plate, Silica gel 60 F254 pre-coated) and developed with MeOHCH2Cl2 (5 : 95, v/v). Spots were also detected under U.V. light at 254 nm wavelength. A high performance liquid chromatograph (HPLC) equipped with a double-scanning detector was used for identification of metabolites. Decrease of the substance observed after 24 hrs of incubation were 90%, 91% and 88% for 5, 10 and 20 ppm of concentrations respectively.Thus, it can be stated that under the given test condition, the test material 2, 4 Diaminoazobenzene is readily biodegradable in water.

Another supporting peer reviewed journal of the same authors (Eiichi Idaka et al;Society of Dyers and Colourists. Journal; 94: 914, 1978) indicates the specificity of the test substance4-(phenylazo)benzene-1,3-diamine to the bacterium Aeromonas hydrophila var. 24B was examined in biodegradation study. The source of the bacteria was effluent from the draining ditches at dyestuff factories. Effluent samples were taken from the draining ditches of dyestuff factories in the Gifu district. The pH was adjusted to 7.0. 0.1 ml of the sample of effluent and was added to a 500-ml shaken flask containing 100 ml of the screening medium. Rotary shaking culture was carried out for 1 day at 37°C. Agar plates (1.576, wt/vol.) composed of screening medium were then inoculated with a loopful of incubated broth and incubated for 3 days at 37°C and, after growth, colonies on the plate were removed and stocked on agar slants. Identification of the isolated bacteria was carried out by the method described by Buchanan and Gibbons. Each dye was added to a sample of the sterilized medium in a 500-ml flask and the sample was then inoculated with agar slant culture. Each flask was incubated for 1 -2 day at 37"C, either by rotary shaking (200 rev/min) or under static condition. The culture broth was centrifuged at 10,000 rev/min for 10 min to remove cells, and the absorbance of the supernatant fraction was measured with a spectrophotometer, after adjustment of pH. After removal of cells from the static culture broth by continuous centrifuging, it was adjusted to pH 11.0 with I-M NaOH and extracted with dichloromethane. The extract was passed through a silica gel column and the metabolites were then separated by thin-layer chromatography (t.1.c.) on silica gel. Metabolites was identified by means of high-performance liquid chromatography. Extent of elimination of the test substance4-(phenylazo)benzene-1,3-diamine after incubation for 24 h with shaking culture was 51%, and after 48 h with static culture was 91%. Thus it can be considered that the test material 2,4-Diaminoazobenzene is readily biodegradable in water.

35-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item 4-(phenylazo)benzene-1,3-

diamine, CAS No. 495-54-5. The test system included control, test item and reference item. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/l. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The BOD35 value of 4-(phenylazo)benzene-1,3-diamine, CAS No. 495-54-5 was observed to be 0.7 mgO2/mg. ThOD was calculated as 1.80 mgO2/mg. Accordingly, the % degradation of the test item after 35 days of incubation at 20 ± 1°C according to Closed Bottle test was found to be 38.88%. Based on the results, the test item, under the test conditions, was considered to be ultimate inherent primary biodegradable over a period of 35 days.

Thus considering the water solubility of the substance i.e. moderately soluble and for the purpose of classification and chemical safety assessment, the study from peer reviewed journal is considered as key study and the substance4-(phenylazo)benzene-1,3-diamine is considered to be readily biodegradable in water.

Biodegradation in water and sediment:
Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound 4(phenylazenyl)benzene-1,3-diamine (CAS No. 495 -54 -5). If released in to the environment, 14.5% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 4(phenylazenyl)benzene-1,3 -diamine in water is estimated to be 60 days (1440 hrs). The half-life (60 days estimated by EPI suite) indicates that the chemical is persistent in water and the exposure risk to aquatic animals ismoderate to high whereas the half-life period of 4(phenylazenyl)benzene-1,3-diamine in sediment is estimated to be 541.66 days (1300 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.826%), indicates that 4(phenylazenyl)benzene-1,3-diamine is not persistent in sediment.

Biodegradation in soil:
The half-life period of4-(phenylazo)benzene-1,3-diamine(CAS No. 495 -54 -5) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 33.3% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of4-(Phenylazo)benzene-1,3-diaminein soil is estimated to be 120 days (2880 hrs). Based on this half-life value of 4-(Phenylazo)benzene-1,3-diamine, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.