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Biodegradation

Biodegradation in water

The predicted data for the test compound1,8-Bis((4-methylphenyl)amino)anthraquinone (CAS no. 82-16-6) and study of its read across substance were reviewed for the biodegradation end point which are summarized as below:

 

Biodegradation in water ability was predicted (SSS QSAR prediction model, 2016) for the test substance1,8-Bis((4-methylphenyl)amino)anthraquinone(CAS no. 82-16-6) using the SSS QSAR prediction model. The ready biodegradability of the test substance1,8-Bis((4-methylphenyl)amino)anthraquinonewas estimated as 30.006% in 7 days by using CO2 evolution parameter. This result indicates that1,8-Bis((4-methylphenyl)amino)anthraquinonewas estimated to be readily biodegradable in water.

Biodegradation study was conducted for 14 days according to OECD TG 301 C guideline for evaluating the percentage biodegradability of test substance Anthraquinone (Kondo, M et. Al; 1988). Initial test substance conc. used in the study was100 mg/l. Namely, a water, acetone or DMSO solution (0.1 ml) of the test chemicals was added to a mixture of river/sea water (4.9 ml) from an unpolluted area and an autoclaved solution (5.0ml) of 0.2% peptone in a sterile test tube with a tight plug. After sealed with film and fixed at an angle of 30°in a dark box,the test tubes were incubated at 30°C and shaked at 120rpm. Inoculum used for the study was mixed culture obtained from different sources (Sea water from Akashi Beach and River water from Mino River). The percentage degradation of test substance was found to be 82% and 91% in 14 days, respectively. Thus, the substance Anthraquinone was found to be readily biodegradable.

 

 

Biodegradation screening test (J-CHECK, 2016) was conducted for 21 days (3 weeks) for evaluating the percentage biodegradability of the test substance Anthraquinone. Concentration of inoculum i.e, sludge is 30 mg/l and initial test substance conc. used in the study was 100 mg/l. The percentage degradation of test substance was found to be 29.7% and 52.3% after 14 and 21 days by BOD, 88.1% by GC and 75.7% by UV-VIS. Thus, the substance Anthraquinone was found to be readily biodegradable in water.

 

Biodegradation study was conducted according to OECD Guideline 301B and OECD Guideline 301C for 24 and 25 days for evaluating the percentage biodegradability of test substance Anthraquinone. Sturm Test and MITI test was used for the biodegradation study

[European Chemical Industry Ecology & Toxicology Centre (ECETOC), 1986].

 

In the Sturm Test, installations and equipment used in the test were as described in the OECD Guideline 301B. The size of the carbosys was reduced from 5 l to 3l and the volume of the solution from 2 to 1.5 l. A magnetic stirrer with a PTFE – coated rod of 6cm length rotating at approximately 60 rpm was used for agitation. A constant temperature of 23°C was maintained by immersion of carbosys in a water bath.

Sludge was taken from a sewage treatment plant receiving predominantly domestic waste water. The inoculum and mineral media were prepared according to OECD Guidelines. In the method with direct dispersion of the test chemical, anthraquinone (20mg/l) was added as a powder or as a suspension in water prepared by ultrasonic dispersion, to the carboys containing the inoculum. No additional treatment was given to the mixture containing the inoculum whereas in the MITI test, sludge was taken from a sewage treatment plant receiving predominantly domestic waste water, washed twice by centrifugation and re-suspension in the test medium. Prior to the start of the test, the bottles were incubated for 1 weeks at the temperature of 22±3°C to reduce the endogenous respiration rate of the inoculum. The test was carried out in a HACH manometric respirometer according to OECD Guideline no. 301C. Conc. of the inoculum used in the MITI was 30 mg/l and initial test substance conc. used in the study was 100 mg/l.The percentage degradation of test substance was found to be 75% by CO2/ ThCO2 and 93% by BOD/ThOD in the Sturn and MITI test. Thus, the substance Anthraquinone was found to be readily biodegradable in water.

 

 

On the basis of above results for target and read across substance, it can be concluded that the test substance can be expected to be readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI) Suite (2016) prediction model was run to predict the half-life in water and sediment for the test compound 1,8-Bis((4-methylphenyl)amino)anthraquinone (CAS no. 82 -16 -6). Half-life of 1,8-Bis((4-methylphenyl)amino)anthraquinone in water is estimated to be 60 days (1440 hrs) while in sediment it is 541.66 days (13000 hrs). Based on these half-life value of 1,8 -Bis((4 -methylphenyl)amino)anthraquinone, it is concluded that the chemical is persistent in both water and sediment.

Biodegradation in soil

Based on EPI prediction Level III Fugacity Model (EPI suite, 2016), the estimated half life period of 1,8-Bis((4-methylphenyl)amino)anthraquinonein soil was obtained to be 120 days (2880 hrs). Based on this half life value of 1,8-Bis((4-methylphenyl)amino)anthraquinone, it is concluded that the chemical is not persistent in the soil environment.

On the basis of available information for the target substance, the test substance can be considered as readilybiodegradable in nature.

Bioaccumulation: aquatic/sediment

The estimated bioconcentration factor (BCF) for 1,8-Bis((4-methylphenyl)amino)anthraquinone was found to be 277.6 L/kg (EPI Suite, 2016), that doesnot exceed the bioconcentration threshold of 2000. Thus it is concluded that 1,8-Bis((4-methylphenyl)amino)anthraquinone is not expected to bioaccumulate in the food chain because it does not exceed the BCF criteria.