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Environmental fate & pathways

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Biodegradation in water

Biodegradability of disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (CAS no. 6798 -03 -4) is predicted using QSAR toolbox version 3.3 (2018) with logKow as the primary descriptor. Test substance undergoes 0.8% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-) was estimated to be not readily biodegradable in water.

Additional information

Biodegradation in water

Predicted data for the target compound disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2 -) (CAS No. 6798-03-4) and various supporting weight of evidence studies for its structurally and functionally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2018) using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (CAS No. 6798-03-4) was estimated.Test substance undergoes 0.8% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-) was estimated to be not readily biodegradable in water.

 

In a supporting weight of evidence study from experimental study report (Sustainability Support Services (Europe) AB, report no. 2519-30-4/01/2016/RBD, 2016) for the read across chemical Tetrasodium 1-acetamido-2-hydroxy-3-(4-((4-sulphonatophenylazo)-7-sulphonato-1-naphthylazo))naphthalene-4,6-disulphonate (CAS no. 2519-30-4),28-days Manometric respirometry test following the OECD guideline 301F to determine the ready biodegradability of the read across item tetrasodium 1 -acetamido-2 -hydroxy-3 -(4 -((4 -sulphonato phenylazo)-7 -sulphonato-1 -naphthylazo))naphthalene-4,6 -disulphonate, CAS No. 2519 -30 -4. 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 30 mg/L, while that of inoculum was 10 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 BOD28 value of tetrasodium 1 -acetamido-2 -hydroxy-3 -(4 -((4 -sulphonatophenylazo)-7 -sulphonato-1 -naphthylazo))naphthalene-4,6 -disulphonate, CAS No. 2519 -30-4 was observed to be 0.050mgO2sup>/mg. ThOD was calculated as 1.088 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 4.596%.Based on the results, the test item, under the test conditions, was considered to be not readily biodegradable at 20 ± 1°C over a period of 28 days.

 

For the read across chemical Disodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonate (CAS no. 3567-66-6), 28-days Manometric respirometry testfollowing the OECD guideline 301Fto determine the ready biodegradability of the test item disodium 5 -amino-4 -hydroxy-3 -(phenylazo)naphthalene-2,7 -disulphonate, CAS No. 3567 -66 -6. 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 30 mg/L, while that of inoculum was 10 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 BOD28 value of disodium 5 -amino-4 -hydroxy-3 -(phenylazo)naphthalene-2,7 -disulphonate, CAS No. 3567-66-6 was observed to be 0.022 mgO2sup>/mg. ThOD was calculated as 1.267 mgO2/mg. Accordingly, the % degradation of the read across item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 1.754 %.Based on the results, the test item, under the test conditions, was considered to be not readily biodegradable at 20 ± 1°C over a period of 28 days.

 

On the basis of above results for target chemical disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (from OECD QSAR toolbox version 3.3, 2018) and for its read across substance (from UERL study report), it can be concluded that the test substance disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-) can be expected to be not readily biodegradable in nature.