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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.3.3 and QMRF report has been attached.
Qualifier:
according to
Guideline:
other: Predicted data
Principles of method if other than guideline:
Prediction is done using QSAR Toolbox version 3.3 with log kow as the primary discriptors.
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material (IUPAC name): 2-aminotoluene-4-sulphonic acid
- Molecular formula: C7H9NO3S
- Molecular weight: 187.218 g/mol
- Smiles notation: O=S(=O)(O)c1ccc(c(N)c1)C
- InChl: 1S/C7H9NO3S/c1-5-2-3-6(4-7(5)8)12(9,10)11/h2-4H,8H2,1H3,(H,9,10,11)
- Substance type: Organic
- Physical state: Solid powder (white to pinkish white)
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
143.869 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" )  and ("e" and ( not "f") )  )  and "g" )  and "h" )  and ("i" and ( not "j") )  )  and ("k" and "l" )  )

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 Moderate binder, NH2 group by Estrogen Receptor Binding

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Acid moiety OR Anilines (Hindered) by Aquatic toxicity classification by ECOSAR ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Radical OR Radical >> Radical mechanism via ROS formation (indirect) OR Radical >> Radical mechanism via ROS formation (indirect) >> Single-Ring Substituted Primary Aromatic Amines OR SN1 OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Single-Ring Substituted Primary Aromatic Amines by DNA binding by OASIS v.1.3 ONLY

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 SN1 OR SN1 >> Nitrenium Ion formation OR SN1 >> Nitrenium Ion formation >> Aromatic azo OR SN1 >> Nitrenium Ion formation >> Aromatic nitro OR SN1 >> Nitrenium Ion formation >> Primary aromatic amine OR SN1 >> Nitrenium Ion formation >> Secondary 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 Reactive unspecified by Acute aquatic toxicity MOA by OASIS ONLY

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Acid moiety AND Anilines (Hindered) by Aquatic toxicity classification by ECOSAR ONLY

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Aromatic amines AND Sulfonic acids or their salts by Skin irritation/corrosion Inclusion rules by BfR

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Inclusion rules not met by Skin irritation/corrosion Inclusion rules by BfR

Domain logical expression index: "k"

Parametric boundary:The target chemical should have a value of log Kow which is >= -3

Domain logical expression index: "l"

Parametric boundary:The target chemical should have a value of log Kow which is <= 0.964

Conclusions:
Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic algae was predicted 2-aminotoluene-4-sulphonic acid (CAS: 618-03-1). EC50 growth rate value was estimated to be 143.869 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that 2-aminotoluene-4-sulphonic acid (CAS: 618-03-1) was likely to be not toxic to aquatic algae.
Executive summary:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic algae was predicted 2-aminotoluene-4-sulphonic acid (CAS: 618-03-1). EC50 growth rate value was estimated to be 143.869 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that 2-aminotoluene-4-sulphonic acid (CAS: 618-03-1) was likely to be not toxic to aquatic algae.

Description of key information

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic algae was predicted 2-aminotoluene-4-sulphonic acid (CAS: 618-03-1). EC50 growth rate value was estimated to be 143.869 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that 2-aminotoluene-4-sulphonic acid (CAS: 618-03-1) was likely to be not toxic to aquatic algae.

Key value for chemical safety assessment

EC50 for freshwater algae:
143.869 mg/L

Additional information

Following three studies of target chemical and structurally similar read across includes predicted data and experimental data to conclude the toxicity extent of 2-aminotoluene-4-sulphonic acid (CAS: 618-03-1) towards aquatic algae is summarized as follows:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic algae was predicted 2-aminotoluene-4-sulphonic acid (CAS: 618-03-1). EC50 growth rate value was estimated to be 143.869 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that 2-aminotoluene-4-sulphonic acid (CAS: 618 -03-1) was likely to be not toxic to aquatic algae.

The above predicted data of target chemical is supported by the experimental study of structurally similar read across 4 -aminobenzenesulfonic acid (CAS no. 121 -57 -3) from secondary source, suggests that the Short term toxicity toScenedesmus subspicatus(green algae) study was carried out for 72 hrs. The study was performed according to other guideline DIN 38412 Part 9, 1992. The study was based on the effects of the test compound 4 -aminobenzenesulfonic acid (CAS no. 121 -57 -3) on Scenedesmus subspicatus(green algae) in a static fresh water system. Scenedesmus subspicatuswas used as a test organism. Based on effect on growth rate of the test organismScenedesmus subspicatus(green algae), the 72 hr EC10 and EC50 value was determined to be 2.7 and 375 mg/l, respectively. Thus, based on the EC50 value, it can be concluded that the substance 4 -aminobenzenesulfonic acid can be considered as non-toxic to aquatic organisms and thus cannot be classified as hazardous as per the CLP classification criteria.

Thus based on the effect concentrations which is in the range 143.869 mg/l to 375 mg/l give the conclusion that test substance 2-aminotoluene-4-sulphonic acid (CAS: 618-03-1) was likely to be not toxic to aquatic algae at environmentally relevant concentrations and can be considered to be “not classified” as per the CLP classification criteria.