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Hydrolysis

The half-life of the test chemical calcium 3-hydroxy-4-[(4-methyl-2-sulfonatophenyl)diazenyl]-2-naphthoate (CAS no. 5281-04-9) was determined at different pH range. The study was performed according to OECD Guideline 111 (Hydrolysis as a Function of pH) at a temperature of 50°C. Although, half-life value of test chemical is not known, but chemical calcium 3-hydroxy-4-[(4-methyl-2-sulfonatophenyl)diazenyl]-2-naphthoatewas reported to be hydrolytically stable at pH 4, 7 and 9, respectively and at a temperature of50⁰C. Based on this, it is concluded that the chemical calcium 3-hydroxy-4-[(4-methyl-2-sulfonatophenyl)diazenyl]-2-naphthoateisnot hydrolysable.

Biodegradation in water

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate (CAS no. 5281 -04 -9) (authoritative databases and secondary source, 2018). The study was performed according toOECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. Activated sludge (non-adapted) was used as a test inoculums for the study. 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 test substance calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate was determined to be 10 and 0% by BOD and HPLC parameter in 28 days. Thus, based on percentage degradation, calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate is considered to be not readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

Bioaccumulation study was conducted on test organism Cyprinus carpio for 6 weeks for evaluating the bioconcentration factor (BCF value) of chemical calcium 3-hydroxy-4-[(4-methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate (CAS no. 5281 -04 -9) (from authoritative databases and secondary source, 2018). The study was performed according to OECD Guideline 305 (Bioconcentration: Flow-through Fish Test) and other guideline "Bioaccumulation test of a chemical substance in fish or shellfish" provided in "the Notice on the Test Method Concerning New Chemical Substances", respectively under flow through conditions at a temperature of 25°C and pH range 6.0-8.5, respectively. Cyprinus carpio (length - 8 dimensionless) was used as a test organism for the study. Test chemical nominal conc. used for the study were 0.3mg/l and 0.03 mg/l, respectively.Test chemical solution was prepared in HCO-40 and Crystal sugar.Analytical method involve therecovery ratio:Fish : 79.6 %, - Limit of quantitation : Test water : 1st concentration area : 0.017 microg/mL, 2nd concentration area : 0.00 microg/mL, Fish : 0.18 microg/g. Range finding study involve theLC50(48h) >= 50.0 mg/Lon Rice fish (Oryzias latipes).The bioconcentration factor (BCF value) of substance calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate on Cyprinus carpio was determined to be in the range of ≤ 0.7 -1.8 L/Kg at a conc. of 0.3 mg/l and ≤ 6.9 L/Kg at a conc. of 0.03 mg/l, respectively, which does not exceed the bioconcentration threshold of 2000, indicating that the chemical calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate is not expected to bioaccumulate in the food chain.

Adsorption / desorption

KOCWIN model of Estimation Programs Interface (2018) was used to predict the soil adsorption coefficient i.e Koc value of test chemical Calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate (CAS No. 5281 -04 -9). The soil adsorption coefficient i.e Koc value of Calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate was estimated to be 8321 L/kg (log Koc=3.9202) by means of MCI method (at 25 deg C). This Koc value indicates that the substance Calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2-naphthoate has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

Additional information

Hydrolysis

The half-life of the test chemical calcium 3-hydroxy-4-[(4-methyl-2-sulfonatophenyl)diazenyl]-2-naphthoate (CAS no. 5281-04-9) was determined at different pH range. The study was performed according to OECD Guideline 111 (Hydrolysis as a Function of pH) at a temperature of 50°C. Although, half-life value of test chemical is not known, but chemical calcium 3-hydroxy-4-[(4-methyl-2-sulfonatophenyl)diazenyl]-2-naphthoatewas reported to be hydrolytically stable at pH 4, 7 and 9, respectively and at a temperature of50⁰C. Based on this, it is concluded that the chemical calcium 3-hydroxy-4-[(4-methyl-2-sulfonatophenyl)diazenyl]-2-naphthoateisnot hydrolysable.

Biodegradation in water

Experimental study for the target compound Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate (CAS No. 5281-04-9) and various supporting studies for its structurally and functionally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from authoritative databases and secondary source (2018), biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test substance calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate (CAS no. 5281 -04 -9). The study was performed according toOECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. Activated sludge (non-adapted) was used as a test inoculums for the study. 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 test substance calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate was determined to be 10 and 0% by BOD and HPLC parameter in 28 days. Thus, based on percentage degradation, calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate is considered to be not readily biodegradable in nature.

 

In a prediction using the Estimation Programs Interface Suite (2017), the biodegradation potential of the test compoundCalcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate(CAS No. 5281-04-9) 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 chemicalCalcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoateis expected to be not readily biodegradable.

 

For the test chemical,28-days Manometric respirometry test following the OECD guideline 301F to determine the ready biodegradability of the test chemical (Experimental study report, 2016). The study was performed at a temperature of 20± 1°C. Mixture of domestic waste water, surface soil and soil samples was used as a test inoculum for the study. This inoculum was collected and were mixed to get diluted suspension. The inoculum was kept aerobic until being used for experiment by supplying organic and inorganic sources required by micro flora to sustain at controlled laboratory conditions.  This gave the bacterial count as 107to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. OECD mineral medium was used for the study. 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 % degradation of procedure control (Sodium Benzoate) was also calculated using BOD & ThOD and was determined to be 74.074%. The mean BOD values (mg O2/l) in control on 28th day was 9 mg O2/l, thereby fulfilling the control validity criteria (i.e., The oxygen consumption of the inoculum blank is normally 20-30 mg O2/l and should not be greater than 60 mg/l in 28 days). Degradation of Sodium Benzoate exceeds 50.050 %after 7 days and 68.068 % after 14 days. The activity of the inoculums is thus verified and the test can be considered as valid.The BOD28 value of test chemical was observed to be 0.022 mgO2sup>/mg. ThOD was calculated as 1.267 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 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.

 

In a supporting study from experimental study report (2016), 28-days Manometric respirometry test following the OECD guideline 301F to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20± 1°C. Mixture of domestic waste water, surface soil and soil samples was used as a test inoculum for the study. This inoculum was collected and were mixed to get diluted suspension. The inoculum was kept aerobic until being used for experiment by supplying organic and inorganic sources required by micro flora to sustain at controlled laboratory conditions.  This gave the bacterial count as 107to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. OECD mineral medium was used for the study. 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 % degradation of procedure control (Sodium Benzoate) was also calculated using BOD & ThOD and was determined to be 74.04%. The mean BOD values(mg O2/l) in control on 28th day was 9 mg O2/l, thereby fulfilling the control validity criteria (i.e., The oxygen consumption of the inoculum blank is normally 20-30 mg O2/l and should not be greater than 60 mg/l in 28 days). Degradation of Sodium Benzoate exceeds 48.04%after 7 days and 66.06% after 14 days. The activity of the inoculums is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.188 mgO2sup>/mg. ThOD was calculated as 1.836 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 10.212%.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 Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate (from authoritative databases and secondary source) and for its read across substance (from experimental study report), it can be concluded that the test substance Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate can be expected to be not readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

Experimental study and various predicted data for the target compound Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate (CAS No. 5281-04-9) and supporting studies for its structurally and functionally similar read across substance were reviewed for the bioaccumulation end point which are summarized as below:

 

In an experimental study from authoritative databases and secondary source (2018), bioaccumulation study was conducted on test organism Cyprinus carpio for 6 weeks for evaluating the bioconcentration factor (BCF value) of chemical calcium 3-hydroxy-4-[(4-methyl-2-sulfonatophenyl)diazenyl]-2-naphthoate (CAS no. 5281-04-9).The study was performed according to OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)andother guideline"Bioaccumulation test of a chemical substance in fish or shellfish" provided in "the Notice on the Test Method Concerning New Chemical Substances", respectively under flow through conditions at a temperature of 25°C and pH range 6.0-8.5, respectively. Cyprinus carpio (length - 8 dimensionless) was used as a test organism for the study. Test chemical nominal conc. used for the study were 0.3mg/l and 0.03 mg/l, respectively.Test chemical solution was prepared in HCO-40 and Crystal sugar.Analytical method involve therecovery ratio:Fish : 79.6 %, - Limit of quantitation : Test water : 1st concentration area : 0.017 microg/mL, 2nd concentration area : 0.00 microg/mL, Fish : 0.18 microg/g. Range finding study involve theLC50(48h) >= 50.0 mg/Lon Rice fish (Oryzias latipes).The bioconcentration factor (BCF value) of substance calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate on Cyprinus carpio was determined to be in the range of ≤ 0.7 -1.8 L/Kg at a conc. of 0.3 mg/l and ≤ 6.9 L/Kg at a conc. of 0.03 mg/l, respectively.

 

In a prediction using the BCFBAF program of Estimation Programs Interface was used to predict the bioconcentration factor (BCF) of test chemical Calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl) diazenyl]-2 -naphthoate (CAS No. 5281 -04 -9) (modelling database, 2018). The bioconcentration factor (BCF) of Calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2-naphthoate was estimated to be 3.162 L/kg whole body w.w (at 25 deg C).

 

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application) model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical), the bioaccumulation i.e BCF for test substance Calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate was estimated to be 8.51 dimensionless (modelling database, 2017) . The predicted BCF result based on the 5 OECD principles.

 

In a supporting study from authoritative database (2018) for the test chemical, bioaccumulation experiment was conducted on test organism Cyprinus carpio for 6 weeks for evaluating the bioconcentration factor (BCF value) of test chemical. The study was performed according to “OECD Guideline 305 C (Bioaccumulation: Test for the Degree of Bioconcentration in Fish)” and other guideline "Bioaccumulation test of a chemical substance in fish or shellfish" provided in "the Notice on the Test Method Concerning New Chemical Substances", respectively. Cyprinus carpio was used as a test organism for the study. Test chemical nominal conc. used for the study were 1 mg/land 0.1 mg/l, respectively. Test chemical solution was prepared in crystal sugar or HCO-40.Analytical method involve therecovery ratio: Fish : 85.8 %, - Limit of quantitation : Test water : 1st concentration area : 0.024 mg/L, 2nd concentration area : 0.0024 mg/L, Fish : 0.28 microg/g. Range finding study involve the LC50 (48hr) ≥ 400 mg/l on Rice fish (Oryzias latipes). Lipid content of the test organism Cyprinus carpio was determined to be 4.2% at start of exposure. The bioconcentration factor (BCF value) of test substance on Cyprinus carpio was determined to be in the range of 0.3 – 2.7 L/Kg at a conc. of 1 mg/l and ≤ 2.9 L/Kg at a conc. of 0.1 mg/l, respectively, which does not exceed the bioconcentration threshold of 2000, indicating that test chemical is not expected to bioaccumulate in the food chain.

 

For the same test chemical from authoritative database (2017), the bioaccumulation study was conducted for estimating the BCF (bioaccumulation factor) value of test chemical. The bioaccumulation factor (BCF) value was calculated using a log Kow of 6.5 and a regression-derived equation. The estimated BCF (bioaccumulation factor) value of test chemical was determined to be 10 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that test chemical is considered to be non-accumulative in aquatic organisms.

 

In an another supporting study from authoritative database (2017) for the test chemical,the bioaccumulation experiment was conducted for estimating the BCF (bioaccumulation factor) value of test chemical. The bioaccumulation factor (BCF) value was calculated using a log Kow of 6.6 and a regression-derived equation. The estimated BCF (bioaccumulation factor) value of test chemical was determined to be 10 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that the test chemical is considered to be non-accumulative in aquatic organisms.

 

On the basis of above results for target chemical Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate (from authoritative database, secondary source and modelling databases,2017), it can be concluded that the BCF value of test substance Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate ranges from 0.7 – 8.51, which does not exceed the bioconcentration threshold of 2000, indicating that the chemical Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate is not expected to bioaccumulate in the food chain.

Adsorption / desorption

Predicted data for the target compound Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate (CAS No. 5281-04-9) and various supporting weight of evidence studies for its structurally and functionally similar read across substance were reviewed for the adsorption end point which are summarized as below:

 

KOCWIN model of Estimation Programs Interface was used to predict the soil adsorption coefficient i.e Koc value of test chemical Calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate (CAS No. 5281 -04 -9). The soil adsorption coefficient i.e Koc value of Calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulfonatophenyl)diazenyl]-2 -naphthoate was estimated to be 8321 L/kg (log Koc=3.9202) by means of MCI method (at 25 deg C).

 

In a supporting weight of evidence study from experimental study report (2016), the adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 50mg of test item and diluted with mobile phase up to 100ml. Thus, the test solution concentration was 500mg/l. The pH of test substance was 6.24. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to structural similarity with the test substance and calibration graph was prepared. The reference substances were Phenol, Aniline, Nitrobenzene, naphthalene, Phenanthrene and DDT having Koc value ranging from 1.32 to 5.63. The Log Koc value of test chemical was determined to be 3.679 ± 0.076 at 25°C.

 

For the test chemical, the adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals (Experimental study report, 2016). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 50mg of test item and diluted with mobile phase up to 100ml. Thus, the test solution concentration was 500mg/l. The pH of test substance was 7.33. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Phenol, 4 methyl aniline, nitrobenzene, toluene, Ethylbenzene, Phenanthrene, and DDT having Koc value ranging from 1.32 to 5.63. The Log Koc value of test chemical was determined to be 3.6 ± 0.06 at 25°C.

 

On the basis of above overall results for target chemical Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate (from modelling databases,2017), it can be concluded that the log Koc value of test substance Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate was estimated to be3.9202indicating that the test chemical Calcium 3 -hydroxy-4 -[(4 -methyl-2 -sulphonatophenyl)azo]-2 -naphthoate has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.