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Biodegradation in water

Biodegradability of 6 -[(2,4 -diaminophenyl)azo]-3 -[[4 -[[4 -[[7 -[(2,4 -diaminophenyl)azo]-1 -hydroxy-3 -sulpho-2 -naphthyl]azo]phenyl]amino]-3 -sulphophenyl]azo]-4 -hydroxynaphthalene-2 -sulphonic acid (CAS no. 76186 -07 -7) is predicted using QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 0.2% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 6 -[(2,4 -diaminophenyl)azo]-3 -[[4 -[[4 -[[7 -[(2,4 -diaminophenyl)azo]-1 -hydroxy-3 -sulpho-2 -naphthyl]azo]phenyl]amino]-3 -sulphophenyl]azo]-4 -hydroxynaphthalene-2 -sulphonic acid was estimated to be not readily biodegradable in water.

Additional information

Biodegradation in water

Various predicted data for the target compound 6 -[(2,4 -diaminophenyl)azo]-3 -[[4 -[[4 -[[7 -[(2,4 -diaminophenyl)azo]-1 -hydroxy-3 -sulpho-2 -naphthyl]azo]phenyl]amino]-3 -sulphophenyl] azo]-4 -hydroxynaphthalene-2 -sulphonic acid (CAS No. 76186-07-7) and supporting weight of evidence studies for its structurally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical6-[(2,4-diaminophenyl)azo]-3-[[4-[[4-[[7-[(2,4-diaminophenyl)azo]-1-hydroxy-3-sulpho-2-naphthyl]azo]phenyl]amino]-3-sulphophenyl]azo]-4-hydroxynaphthalene-2-sulphonic acid(CAS No. 76186-07-7) was estimated.Test substance undergoes 0.2% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical6-[(2,4-diaminophenyl)azo]-3-[[4-[[4-[[7-[(2,4-diaminophenyl)azo]-1-hydroxy-3-sulpho-2-naphthyl]azo]phenyl]amino]-3-sulphophenyl]azo]-4-hydroxynaphthalene-2-sulphonic acidwas estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound 6 -[(2,4 -diaminophenyl)azo]-3 -[[4 -[[4 -[[7 -[(2,4 -diaminophenyl)azo]-1 -hydroxy-3 -sulpho-2 -naphthyl]azo]phenyl]amino]-3-sulphophenyl]azo]-4-hydroxynaphthalene-2-sulphonic acid(CAS No. 76186-07-7) in the presence of mixed populations of environmental microorganisms was estimated.The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical 6 -[(2,4 -diaminophenyl)azo]-3 -[[4 -[[4 -[[7 -[(2,4 -diaminophenyl)azo]-1 -hydroxy-3 -sulpho-2 -naphthyl]azo]phenyl]amino]-3 -sulphophenyl]azo]-4 -hydroxynaphthalene-2 -sulphonic acid is expected to be not readily biodegradable.

 

In a supporting weight of evidence study from peer reviewed journal (U. Pagga and O. Brown; 1986) for the read across chemical disodium 7 -amino-4 -hydroxy-3 -[(E)-2 -(4 -{4 -[(E)-2 -(1 -hydroxy-4 -sulfonatonaphthalen-2 -yl)diazen-1 -yl]-3 -methoxyphenyl}-2-methoxyphenyl)diazen-1-yl]naphthalene-2-sulfonate (CAS no. 6449-35-0),biodegradation experiment was carried out for 42 days for evaluating the percentage biodegradation of the read across chemical disodium 7 -amino-4 -hydroxy-3 -[(E)-2 -(4 -{4 -[(E)-2 -(1 -hydroxy-4 -sulfonatonaphthalen-2 -yl)diazen-1 -yl]-3 -methoxyphenyl}-2 -methoxyphenyl)diazen-1 -yl]naphthalene-2-sulfonate using modified OECD Guideline 302B. Activated sludge was used as a test inoculum. The sources of the activated sludge were treatment plants conveniently located to the laboratories carrying out the test. These treatment plants received communal and/or industrial wastewater. Concentration of inoculum i.e, activated sludge used was 0.5 g/l and initial test substance conc. used in the study was 100 mg/l. Analytical methods involve the measurement of extinction at absorption maximum 412 nm and DOC (dissolved organic carbon).The percentage degradation of the test substance disodium 7 -amino-4 -hydroxy-3 -[(E)-2 -(4 -{4 -[(E)-2 -(1 -hydroxy-4 -sulfonatonaphthalen-2 -yl)diazen-1 -yl]-3 -methoxyphenyl}-2 -methoxyphenyl)diazen-1 -yl]naphthalene-2 -sulfonate was determined to be 44% by using DOC removal parameter in 42 days. Thus, based on percentage degradation, the chemical disodium 7 -amino-4 -hydroxy-3 -[(E)-2 -(4 -{4 -[(E)-2 -(1 -hydroxy-4 -sulfonatonaphthalen-2 -yl)diazen-1 -yl]-3 -methoxyphenyl}-2 -methoxyphenyl)diazen-1 -yl]naphthalene-2 -sulfonate was considered to be not readily biodegradable in nature.

 

For the read across chemical Tetrasodium 3,3'-[(3,3'-dimethoxy[1,1'-biphenyl]-4,4'-diyl)bis(azo)]bis[5-amino-4-hydroxynaphthalene-2,7-disulphonate] (CAS no. 2429-74-5) from authoritative database (J-CHECK and HSDB, 2017), biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance Tetrasodium 3,3'-[(3,3'-dimethoxy[1,1'-biphenyl]-4,4'-diyl)bis(azo) ]bis[5 -amino-4 -hydroxynaphthalene-2,7 -disulphonate]. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) under aerobic conditions. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of substance Tetrasodium 3,3'-[(3,3'-dimethoxy[1,1'-biphenyl]-4,4'-diyl)bis(azo)]bis[5-amino-4-hydroxynaphthalene-2,7-disulphonate] was determined to be 4, 1 and 2% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, Tetrasodium 3,3'-[(3,3'-dimethoxy[1,1'-biphenyl] -4,4'-diyl)bis(azo)] bis[5-amino-4-hydroxynaphthalene-2,7-disulphonate] is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical 6 -[(2,4 -diaminophenyl)azo]-3 -[[4 -[[4 -[[7 -[(2,4 -diaminophenyl)azo]-1 -hydroxy-3 -sulpho-2 -naphthyl]azo]phenyl]amino]-3 -sulpho phenyl]azo]-4 -hydroxynaphthalene-2 -sulphonic acid(from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from peer reviewed journal and authoritative database J-CHECK & HSDB), it can be concluded that the test substance 6 -[(2,4 -diaminophenyl)azo]-3 -[[4 -[[4 -[[7 -[(2,4 -diaminophenyl)azo]-1 -hydroxy-3 -sulpho-2 -naphthyl]azo]phenyl]amino]-3 -sulphophenyl]azo]-4 -hydroxynaphthalene-2 -sulphonic acid can be expected to be not readily biodegradable in nature.