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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:
The supporting QMRF report has been attached
Reference:
Composition 1
Qualifier:
according to
Guideline:
other: Modeling database
Principles of method if other than guideline:
Prediction is done using OECD QSAR Toolbox version 3.4 with logKow as the primary descriptor.
GLP compliance:
not specified
Test material information:
Composition 1
Specific details on test material used for the study:
- Name of test material: 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid
- Molecular formula: C10H9NO7S2
- Molecular weight: 319.3131 g/mol
- Smiles notation: c1cc(c(c2c1c(cc(c2)S(=O)(=O)O)O)S(=O)(=O)O)N
- InChl: 1S/C10H9NO7S2/c11-8-2-1-6-7(10(8)20(16,17)18)3-5(4-9(6)12)19(13,14)15/h1-4,12H,11H2,(H,13,14,15)(H,16,17,18)
- Physical state: Solid
- Substance type: Organic
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Remarks on exposure duration:
No data available
Post exposure observation period:
No data available
Hardness:
178mg CaCO3/L
Test temperature:
23°C ± 2°C
pH:
8.1
Dissolved oxygen:
96 - 97%
Reference substance (positive control):
not specified
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
134.568 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: No more data available
Details on results:
Based on the growth rte inhibition, the EC50 was 134.567 mg/l.

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" or "f" )  and "g" )  and ("h" and ( not "i") )  )  and ("j" and ( not "k") )  )  and ("l" and ( not "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 Anilines (Acute toxicity) by US-EPA New Chemical Categories

Domain logical expression index: "c"

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

Domain logical expression index: "d"

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

Domain logical expression index: "e"

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 Anilines by Protein binding by OASIS v1.4

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Acid moiety AND Anilines (Unhindered) AND Phenol Amines AND Phenols by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "g"

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: "h"

Referential boundary: The target chemical should be classified as Acid moiety AND Anilines (Unhindered) AND Phenol Amines AND Phenols by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Phenols, Poly by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as No alert found by Carcinogenicity (genotox and nongenotox) alerts by ISS

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as Aromatic diazo (Genotox) OR Structural alert for genotoxic carcinogenicity by Carcinogenicity (genotox and nongenotox) alerts by ISS

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Not known precedent reproductive and developmental toxic potential by DART scheme v.1.0

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Known precedent reproductive and developmental toxic potential OR Toluene and small alkyl toluene derivatives (8a) by DART scheme v.1.0

Domain logical expression index: "n"

Parametric boundary:The target chemical should have a value of log Kow which is >= -4.66

Domain logical expression index: "o"

Parametric boundary:The target chemical should have a value of log Kow which is <= 0.966

Validity criteria fulfilled:
not specified
Conclusions:
The median Effective concentration (EC50) value for 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid on Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) in a 72 hour study was estimated to be 134.567 mg/L on the basis of effects on growth rate.
Executive summary:

Using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (CAS no. 6535 -70 -2). EC50 value was estimated to be 134.567 mg/l for Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 h duration. Based on this value it can be concluded that the substance 2-amino-5-hydroxynaphthalene -1,7-disulfonic acid is considered to be non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

Description of key information

Using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (CAS no. 6535 -70 -2). EC50 value was estimated to be 134.567 mg/l for Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 h duration. Based on this value it can be concluded that the substance 2-amino-5-hydroxynaphthalene -1,7-disulfonic acid is considered to be non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
134.567 mg/L

Additional information

Short term toxicity to aquatic algae:

Various predicted data for the target compound 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (6535 -70 -2) and supporting weight of evidence studies for its closest read across substance with log Kow as the primary descriptor were reviewed for the toxicity on the algae end point which are summarized as below:

In a prediction done by SSS (2017), Using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (CAS no. 6535 -70 -2). EC50 value was estimated to be 134.567 mg/l for Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 h duration. Based on this value it can be concluded that the substance 2-amino-5-hydroxynaphthalene -1,7-disulfonic acid is considered to be non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

 

In second prediction using the Danish QSAR, 2017, Based on the prediction done using the three different models i.e, Battery, Leadscope and SciQSAR used within Danish QSAR database, the short term toxicity on green algae was predicted for test substance 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (CAS: 6535 -70 -2). The average EC50 value was given by the third model i.e, Battery model. On the basis of effects observed in a static freshwater system, the effect concentration EC50 value for the substance 2-amino-5-hydroxynaphthalene -1,7- disulfonic acid is estimated to be 23005 mg/l for Pseudokirchneriella subcapitata during 72 hr. exposure duration. Thus, on the basis of EC50 value, it can be concluded that the test chemical 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid can be considered as non-toxic to green algae at environmentally relevant concentrations and can be considered not-classified as per the CLP classification criteria.

 

Similarly in a supporting weight of evidence study from ABITEC report 2016 for read across chemical 4-amino-5-hydroxynaphthalene-1,7-disulphonic acid (130-23-4) toxicity experiment was conducted for evaluating the effect of read across substance. Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance 4-amino-5-hydroxynaphthalene-1,7-disulphonic acid according to OECD Guideline 201. The test substance was dissolved in OECD growth medium and tested at the concentrations 0, 2.2, 11, 25, 55 and 120 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (ErC50) for the test substance, 4-amino-5-hydroxynaphthalene-1,7-disulphonic acid, in Desmodesmus subspicatus was determined to be 129.4 mg/L. Based on this ErC50 value and after comparing with CLP criteria for aquatic classification of the substance it is concluded that the substance 4-amino-5-hydroxynaphthalene-1,7-disulphonic acid does not exhibit toxicity to aquatic algae (Desmodesmus subspicatus) and not classified as toxic as per the CLP classification criteria.

 

Similarly for the same read across chemical, toxicity study was conducted and reported from UERL lab, 2016, The effect of test item 4-amino-5-hydroxynaphthalene -1,7-disulphonic acid, CAS No. 130-23-4 was studied on the growth of fresh water green alga Chlorella vulgaris. The study was conducted following OECD guideline 201- Alga, growth inhibition test. The test concentration chosen for the study were 6.25mg/l, 12.5mg/l, 25mg/l, 50mg/l, 100mg/l and 200mg/l. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be >200mg/l. Thus, based on the EC50 value, test substance 4-amino-5-hydroxynaphthalene-1,7-disulphonic acid can be classified as not hazardous and nontoxic as per the criteria of CLP regulation.

 

Similarly in a third supporting weight of evidence study from ABITEC report 2016 for read across chemical 5-amino-4-hydroxy-3-(phenylazo)naphthalene -2,7- disulphonate (3567-66-6), Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance disodium 5-amino-4-hydroxy- 3-(phenylazo)naphthalene -2,7-disulphonate according to OECD Guideline 201. The test substance was dissolved in OECD growth medium and tested at the concentrations 0, 0, 12.5, 25, 100, 200 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (ErC50) for the test substance, disodium 5-amino-4-hydroxy- 3-(phenylazo)naphthalene-2,7-disulphonate, in Desmodesmus subspicatus was determined to be 330.2 mg/L. Based on this ErC50 value and after comparing with CLP criteria for aquatic classification of the substance it is concluded that the substance disodium 5-amino-4-hydroxy-3- (phenylazo) naphthalene-2,7-disulphonate does not exhibit toxicity to aquatic algae (Desmodesmus subspicatus) and not classified as toxic as per the CLP classification criteria.

 

 

On the basis of above results for target chemical 2-amino-5-hydroxynaphthalene-1,7-disulfonic acid (6535 -70 -2) (from OECD QSAR toolbox version 3.4, and Danish QSAR, 2017) and for its read across substance from ABITEC report and UERL, it can be concluded that the test substance 2-amino-5-hydroxynaphthalene-1,7- disulfonic acid is not toxic and can be consider to be not classified as toxic as per the CLP classification criteria.