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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
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:
Data is from OECD QSAR toolbox version.3.4 and QMRF report has been attached.
Reference:
Composition 1
Qualifier:
according to
Guideline:
other: predicted data
Principles of method if other than guideline:
Prediction is done using QSAR Toolbox version 3.4 with log kow as the primary discriptors.
GLP compliance:
not specified
Test material information:
Composition 1
Specific details on test material used for the study:
- Name of test material: 5-acetamido-2-aminobenzenesulphonic acid
- IUPAC name: 2-amino-5-acetamidobenzene-1-sulfonic acid
- Molecular formula: C8H10N2O4S
- Molecular weight: 230.243 g/mole
- Smiles :O=C(Nc1ccc(N)c(S(=O)(=O)O)c1)C
- Inchl: 1S/C8H10N2O4S/c1-5(11)10-6-2-3-7(9)8(4-6)15(12,13)14/h2-4H,9H2,1H3,(H,10,11)(H,12,13,14)
- Substance type: Organic
- Physical state: Solid crystal powder (white to yellowish grey)
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
117.56 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: not toxic

The prediction was based on dataset comprised from the following descriptors: EC50
Estimation method: Takes average value from the 5 nearest neighbours
Domain  logical expression:Result: In Domain

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

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Anilines (Acute toxicity) by US-EPA New Chemical Categories

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Radical AND Radical >> Radical mechanism via ROS formation (indirect) AND Radical >> Radical mechanism via ROS formation (indirect) >> Single-Ring Substituted Primary Aromatic Amines AND SN1 AND SN1 >> Nucleophilic attack after nitrenium ion formation AND SN1 >> Nucleophilic attack after nitrenium ion formation >> Single-Ring Substituted Primary Aromatic Amines by DNA binding by OASIS v.1.4

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Strong binder, NH2 group by Estrogen Receptor Binding

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Acylation AND Acylation >> Acylation involving an activated (glucuronidated) carboxamide group AND Acylation >> Acylation involving an activated (glucuronidated) carboxamide group >> Carboxylic Acid Amides AND Acylation >> Direct acylation involving a leaving group AND Acylation >> Direct acylation involving a leaving group >> Carboxylic Acid Amides AND Acylation >> Ester aminolysis AND Acylation >> Ester aminolysis >> Amides AND AN2 AND AN2 >> Michael-type addition to quinoid structures  AND AN2 >> Michael-type addition to quinoid structures  >> Carboxylic Acid Amides AND AN2 >> Michael-type addition to quinoid structures  >> Substituted Anilines by Protein binding by OASIS v1.4

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Acylation AND Acylation >> Direct Acylation Involving a Leaving group AND Acylation >> Direct Acylation Involving a Leaving group >> Acetates by Protein binding by OECD

Domain logical expression index: "f"

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: "g"

Referential boundary: The target chemical should be classified as Very fast by Bioaccumulation - metabolism half-lives ONLY

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Non-Metals by Groups of elements

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Alkali Earth OR Alkaline Earth OR Halogens by Groups of elements

Domain logical expression index: "j"

Similarity boundary:Target: CC(=O)Nc1ccc(N)c(S(O)(=O)=O)c1
Threshold=40%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as Stable form by Tautomers unstable

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Conjugated ketoamine(scy) - 1,5-H shift OR Imine form - 1,3-H shift by Tautomers unstable

Domain logical expression index: "m"

Parametric boundary:The target chemical should have a value of log Kow which is >= -3.31

Domain logical expression index: "n"

Parametric boundary:The target chemical should have a value of log Kow which is <= -2.08

Conclusions:
Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the closest read across substances, the toxicity on aquatic algae was predicted 2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6). Effect concentration i.e EC50 value was estimated to be 117.56 mg/l for Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs duration. It was concluded that the 2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6) was likely to be not toxic to aquatic algae, hence it can be considered to be “not Classified” as per the CLP classification criteria for aquatic environment.
Executive summary:

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the closest read across substances, the toxicity on aquatic algae was predicted 2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6). Effect concentration i.e EC50 value was estimated to be 117.56 mg/l for Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs duration. It was concluded that the 2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6) was likely to be not toxic to aquatic algae, hence it can be considered to be “not Classified” as per the CLP classification criteria for aquatic environment.

Description of key information

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the closest read across substances, the toxicity on aquatic algae was predicted 2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6). Effect concentration i.e EC50 value was estimated to be 117.56 mg/l for Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs duration. It was concluded that the 2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6) was likely to be not toxic to aquatic algae, hence it can be considered to be “not Classified” as per the CLP classification criteria for aquatic environment.

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
117.56 mg/L

Additional information

Following studies includes predicted data and experimental data of target chemical and stucturally similar read across to conclude the

2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6) toxicity towards aquatic algae is summarized as below:

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the closest read across substances, the toxicity on aquatic algae was predicted 2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6). Effect concentration i.e EC50 value was estimated to be 117.56 mg/l for Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs duration. It was concluded that the 2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6) was likely to be not toxic to aquatic algae, hence it can be considered to be “not Classified” as per the CLP classification criteria for aquatic environment.

The above predicted data is supported by the experimental syudy of stucturally similar read across 4-amino-3-methylbenzenesulfonic acid; 3 - methylsulphanilic acid ( CAS: 98 -33 -9) from ABITEC Lab. 2017, indicates that the Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance 4-amino-3- methylbenzenesul- fonic acid according to OECD Guideline 201.

The test substance was dissolved in OECD growth medium and tested at the concentrations 0, 0, 30, 45, 67, 100, 150 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (EC50) for the test substance 4-amino-3-methylbenzene- sulfonic acid, in Desmodesmus subspicatus was determined to be 110.6 mg/L

This value indicates that the substance is likely to be non-hazardous to aquatic algae.

Similar study of another stucturally similar read across 2,4-diaminobenzenesulfonic acid (CAS: 88-63-1) from ABITEC Lab. 2017, indicates that the Short term toxicity study to algae was performed according to the OECD guideline 201 in a static system.

The test substance was dissolved in OECD growth medium and tested at the concentrations 0, 0, 30, 45, 67, 100, 150 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (EC50) for the test substance 2,4-diaminobenzenesulfonic acid in Desmodesmus subspicatus is 110.0 mg/L on the basis of effects on growth rate in a 72 hour study. It can be concluded from the value  that the 2,4-diaminobenzenesulfonic acid is not toxic to the aquatic environment.

Thus based on the effect concentrations which is in the range 110.0 mg/l to 117.56 mg/Lgive the conclusion that test substance 2-amino-5-acetamidobenzene-1-sulfonic acid (CAS: 96-78-6) was likely to be not toxic to aquatic algae at environmentally relevant concentrations and applying the weight of evidence approach it can be considered to benot classifiedas per the CLP classification criteria.