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Biodegradation in water

Biodegradability of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (CAS no. 6535 -70 -2) is predicted using OECD QSAR toolbox version 3.4 (2017) with logKow as the primary descriptor. Test substance undergoes 0.86% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid was estimated to be not 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 2 -amino-5 -hydroxynaphthalene-1,7 -disulfonic acid (CAS No. 6535 -70 -2). If released in to the environment, 11.5% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid in water is estimated to be 37.5 days (900 hrs). The half-life (37.5 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid in sediment is estimated to be 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 2% (i.e, reported as 1.03%), indicates that

2-amino-5-hydroxynaphthalene-1,7-disulfonic acid is not persistent in sediment.

Biodegradation in soil

The half-life period of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (CAS No. 6535 -70 -2) 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, 87.5% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of

2-amino-5-hydroxynaphthalene-1,7-disulfonic acid in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid

, 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.

Additional information

Biodegradation in water

Various predicted data for the target chemical 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (CAS No. 6535-70-2) and supporting weight of evidence studies for its 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 3.4 with logKow as the primary descriptor, percentage biodegradability of test chemical2-amino-5-hydroxynaphthalene-1,7-disulfonic acid(CAS No. 6535-70-2) was estimated.Test substance undergoes 0.86% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid was 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 compound2-amino-5-hydroxynaphthalene-1,7-disulfonic acid(CAS No. 6535-70-2) 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 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid is expected to be not readily biodegradable.

 

In a supporting weight of evidence study from peer reviewed journal (Toshihide Saito et. al; 1984) for the read across chemical 2-Chlorobenzoic acid (CAS no. 118-91-2), biodegradation experiment was conducted for evaluating the percentage biodegradability of read across substance 1,3 -Naphthalenedisulfonic acid, 7 -hydroxy-8 -((4 -sulfo-1 -naphthalenyl)azo)-, trisodium salt (CAS no. 2611 -82 -7). Activated sludge was used as a test inoculum obtained from municipal sewage. Test substance of conc. 500 mg/l was prepared and diluted as needed.The COD measurement was performed by the potassium dichromate reflux method based on Japanese Industrial Standards. In the BOD measurement, a sample solution was taken into a container. Then JIS-BOD testing solutions, i.e. 3 ml of A solution and 1 ml of B, C, D solutions were added to the sample solution, respectively. Then 5 ml of the supernatant of the municipal sewage activated sludge was added to the sample solution and diluted to 300 ml with water. Immediately, the BOD-time curve was recorded at 20~ using an Ohkura OM-200I type coulometer. The TOC measurement was carried out by a Yanagimoto TOC-ILW.BOD5, COD, ThOD and TOC value of the test chemical 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-, trisodium salt was determined to be 0.021, 0.65, 1.23 and 0.20 g/g, respectively. The BOD5/TOC ratio of chemical 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-, trisodium salt was determined to be 0.11 (i.e. ranges in between 0.08-0.89), indicating that the chemical is highly resistant to aerobic biodegradation. Thus, based on this value BOD5/TOC value, it can be concluded that the chemical 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-, trisodium salt is not readily biodegradable in nature.

 

Another biodegradation study from peer reviewed journal (U. Pagga and O. Brown, 1986) was carried out for 48 days for evaluating the percentage biodegradation of the same read across chemical 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-, trisodium salt (CAS no. 2611-82-7) 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 substance 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-, trisodium salt was determined to be 5% by DOC removal. Based on the limit values for classification of Static Test – the test chemical was classified in CATEGORY ‘D’. Thus, the substance 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-, trisodium salt is considered to be not readily biodegradable in nature.

 

For the read across chemical 6-aminonaphthalene-1,3-disulfonic acid (CAS no. 118-33-2), biodegradation study was conducted for 9 days for evaluating the percentage biodegradability of read across substance 6 -aminonaphthalene-1,3 -disulfonic acid (J. Ruff, et. al; 1999). Test chemical 6 -aminonaphthalene-1,3 -disulfonic acid was purchased from TCI (Tokyo) at the highest purity available. Glassware was cleaned thoroughly and care taken to exclude extraneous sulfur. Pseudomonas putida strain S-313 was used as a test inoculum obtained from activated sludge from sewage treatment plants in Konstanz, Germany (largely communal) and Ludwigshafen, Germany (largely industrial).Initial experiments were done with the phosphate-buffered medium. The sulfur-free acetate-Tris-buffered salts medium gave the same products with negligible background growth, and thus used as a standard medium.Sulfur was provided at 50µM, except for disulfonates, where the initial sulfonate concentration was 30µM.Cultures were grown in screw-capped tubes on a roller at 30°C.Samples were taken at 3-day intervals for 9 days. Bacteria were removed by centrifugation and the protein content measured, and 100µl portions of the supernatant fluid were examined by HPLC. Substrates and products were determined by isocratic reversed-phase high-pressure liquid chromatography (HPLC) or by ion-pair chromatography. The apparatus included a diode array detector. Chromatograms were initially evaluated with wavelength settings of 245 nm for the amino-naphthalenedisulfonates. Protein was assayed by a Lowry-type method. The percentage degradation of test chemical 6 -aminonaphthalene-1,3 -disulfonic acid was determined to be 0% by using Pseudomonas putida strain S-313 as an inoculum. Thus, based on percentage degradation, chemical 6 -aminonaphthalene-1,3 -disulfonic acid can be considered to be not readily biodegradable in nature.

 

Additional biodegradation study was conducted for 30 days under aerobic conditions for evaluating the percentage biodegradability of test substance 6 -aminonaphthalene-1,3 -disulfonic acid (CAS no. 118 -33 -2) (from peer reviewed journal GREIM H. et. al; 1994 and from secondary source). The study was performed according to OECD Guideline 301 D "Ready Biodegradability: Closed Bottle Test". Initial test substance conc. used in the study were 3, 10 and 30 mg/l, respectively. The percentage degradation of test substance 6 -aminonaphthalene-1,3 -disulfonic acid was determined to be 0% by BOD parameter in 30 days. Thus, based on percentage degradation, 6 -aminonaphthalene-1,3 -disulfonic acid is considered to be not readily biodegradable in nature.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017) for the read across chemical 2-aminonaphthalene-1,5-disulfonic acid (CAS no. 117-62-4), biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance 2-aminonaphthalene-1,5-disulfonic acid. 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 was determined to be 1, 5 and 0% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, 2 -aminonaphthalene-1,5 -disulfonic acid is considered to be not readily biodegradable in water.

 

On the basis of above results for target chemical 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid(from OECD QSAR toolbox version 3.4 and EPI suite, 2017) and for its read across substance (peer reviewed journals,authoritative database J-CHECK andsecondary source), it can be concluded that the test substance2-amino-5-hydroxynaphthalene-1,7-disulfonic acidcan be expected to be not readily biodegradable in nature.

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 2 -amino-5 -hydroxynaphthalene-1,7 -disulfonic acid (CAS No. 6535 -70 -2). If released in to the environment, 11.5% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid in water is estimated to be 37.5 days (900 hrs). The half-life (37.5 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid in sediment is estimated to be 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 2% (i.e, reported as 1.03%), indicates that

2-amino-5-hydroxynaphthalene-1,7-disulfonic acid is not persistent in sediment.

Biodegradation in soil

The half-life period of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (CAS No. 6535 -70 -2) 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, 87.5% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of

2-amino-5-hydroxynaphthalene-1,7-disulfonic acid in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid

, 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.

On the basis of available information, the test substance 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid can be considered to be not readily biodegradable in nature.