Disodium 8-hydroxynaphthalene-1,6-disulphonate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: screening tests

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

The supporting QMRF report has been attached

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Principles of method if other than guideline:

The data is predicted using the OECD QSAR toolbox version 3.4 with logKow as the primary descriptor.

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material (IUPAC name): Disodium 8-hydroxynaphthalene-1,6-disulfonate
- Molecular formula: C10H6Na2O7S2
- Molecular weight: 348.2624 g/mol
- Smiles notation: c1cc2cc(cc(c2c(c1)S(=O)(=O)[O-])O)S(=O)(=O)[O-].[Na+].[Na+]
- InChl: 1S/C10H8O7S2.2Na/c11-8-5-7(18(12,13)14)4-6-2-1-3-9(10(6)8)19(15,16)17;;/h1-5,11H,(H,12,13,14)(H,15,16,17);;/q;2*+1/p-2
- Substance type: Organic
- Physical state: Solid

Oxygen conditions:

aerobic

Inoculum or test system:

other: Microorganisms

Duration of test (contact time):

28 d

Based on:

not specified

Parameter followed for biodegradation estimation:

other: BOD

Key result

Parameter:

other: BOD

Value:

1.1

Sampling time:

28 d

Remarks on result:

other: Other details not known

Details on results:

Test substance undergoes 1.1% degradation by BOD in 28 days.

The prediction was based on dataset comprised from the following descriptors: BOD
Estimation method: Takes average value from the 6 nearest neighbours
Domain  logical expression:Result: In Domain

(((((((((("a" or "b" or "c" or "d" )  and ("e" and ( not "f") )  )  and "g" )  and "h" )  and "i" )  and "j" )  and "k" )  and "l" )  and "m" )  and ("n" and "o" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Naphthalene sulfonic acids, condensates by OECD HPV Chemical Categories

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Strong binder, OH group by Estrogen Receptor Binding

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as AN2 AND AN2 >> Michael-type addition to quinoid structures  AND AN2 >> Michael-type addition to quinoid structures  >> Substituted Phenols by Protein binding by OASIS v1.4

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Acid moiety AND Phenols AND Salt by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OECD

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Michael addition OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Alkyl phenols OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Arenes OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Hydroquinones OR SN1 OR SN1 >> Carbenium Ion Formation OR SN1 >> Carbenium Ion Formation >> Allyl benzenes OR SN1 >> Iminium Ion Formation OR SN1 >> Iminium Ion Formation >> Aliphatic tertiary amines OR SN1 >> Nitrenium Ion formation OR SN1 >> Nitrenium Ion formation >> Aromatic azo OR SN1 >> Nitrenium Ion formation >> Aromatic nitro OR SN1 >> Nitrenium Ion formation >> Aromatic phenylureas OR SN1 >> Nitrenium Ion formation >> Primary aromatic amine OR SN1 >> Nitrenium Ion formation >> Tertiary aromatic amine by DNA binding by OECD

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as days - weeks by Biodeg primary (Biowin 4) ONLY

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 1) ONLY

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as weeks - months by Biodeg ultimate (Biowin 3) ONLY

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Not calculated by Hydrolysis half-life (pH 6.5-7.4) ONLY

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as Class 5 (Not possible to classify according to these rules) by Acute aquatic toxicity classification by Verhaar (Modified) ONLY

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Reactive unspecified by Acute aquatic toxicity MOA by OASIS ONLY

Domain logical expression index: "m"

Similarity boundary:Target: Oc1cc(S(=O)(=O)O{-}.[Na]{+})cc2cccc(S(=O)(=O)O{-}.[Na]{+})c12
Threshold=40%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "n"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 303 Da

Domain logical expression index: "o"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 379 Da

Validity criteria fulfilled:

not specified

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test chemical Disodium 8-hydroxynaphthalene-1,6-disulfonate was estimated to be not readily biodegradable in water.

Executive summary:

Biodegradability of Disodium 8-hydroxynaphthalene-1,6-disulfonate (CAS no. 83732 -80 -3) is predicted using QSAR toolbox version 3.4 with logKow as the primary descriptor. Test substance undergoes 1.1% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical Disodium 8-hydroxynaphthalene-1,6-disulfonate was estimated to be not readily biodegradable in water.

Description of key information

Biodegradability of Disodium 8-hydroxynaphthalene-1,6-disulfonate (CAS no. 83732 -80 -3) is predicted using QSAR toolbox version 3.4 (2017) with logKow as the primary descriptor. Test substance undergoes 1.1% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical Disodium 8-hydroxynaphthalene-1,6-disulfonate was estimated to be not readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Predicted data for the target compound Disodium 8-hydroxynaphthalene-1,6-disulfonate (CAS No. 83732-80-3) and various 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 3.4 with logKow as the primary descriptor, percentage biodegradability of test chemical Disodium 8-hydroxy naphthalene-1,6-disulfonate(CAS No. 83732-80-3) was estimated.Test substance undergoes 1.1% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemicalDisodium 8-hydroxynaphthalene-1,6-disulfonatewas estimated to be not readily biodegradable in water.

 

In a supporting weight of evidence study from study report (Sustainability Support Services (Europe) AB, Report no. 4548-53-2/01/2016/RBD, 2016) for the read across chemical Disodium 3-[(2,4-dimethyl-5-sulphonatophenyl)azo]-4-hydroxynaphthalene-1-sulphonate (CAS no. 4548-53-2), 28-days Manometric respirometry testfollowing the OECD guideline 301F to determine the ready biodegradability of the read across item disodium 3- [(2,4 -dimethyl-5 -sulphonatophenyl)azo]-4 -hydroxynaphthalene-1 -sulphonate. 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 3-[(2,4-dimethyl-5- sulphonatophenyl)azo]-4-hydroxynaphthalene-1-sulphonate, CAS No. 4548-53-2 was observed to be mgO2sup>/mg. ThOD was calculated as mgO2/mg. Accordingly, the % degradation of the read across item Disodium 3-[(2,4-dimethyl-5-sulphonatophenyl)azo]-4-hydroxynaphthalene-1-sulphonate after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 12.807 %.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 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-, trisodium salt (CAS no. 2611-82-7) from peer reviewed journal (U. Pagga and O. Brown, 1986), biodegradation study was carried out for 48 days for evaluating the percentage biodegradation of the read across chemical 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-, trisodium salt 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.

 

Another biodegradation study 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) (Toshihide Saito et. al, 1984). 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.

 

On the basis of above results for target chemical Disodium 8-hydroxynaphthalene-1,6-disulfonate (from OECD QSAR toolbox version 3.4, 2017) and for its read across substance (from peer reviewed journals and study report), it can be concluded that the test substance Disodium 8-hydroxynaphthalene-1,6-disulfonate can be expected to be not readily biodegradable in nature.