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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:
QMRF report has been attached
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Principles of method if other than guideline:
Prediction is done using QSAR Toolbox version 3.3
GLP compliance:
not specified
Specific details on test material used for the study:
- IUPAC name: disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo]naphthalene-2-sulphonato]](6-)]]dicuprate(2-)
- Molecular formula: C32H19Cu2N7Na2O14S4
- Molecular weight: 1026.87 g/mole
- Smiles: c1(S(=O)(=O)[O-])c(\N=N\c2cc(ccc2[O-])S(=O)(=O)N)c([O-])c2ccc(Nc3cc4cc(c(\N=N\c5c(ccc(c5)S(=O)(=O)N)[O-])c(c4cc3)[O-])S(=O)(=O)[O-])cc2c1.[Na+].[Na+].[Cu+2].[Cu+2]
- Inchl: 1S/C32H25N7O14S4.2Cu.2Na/c33-54(44,45)19-3-7-25(40)23(13-19)36-38-29-27(56(48,49)50)11-15-9-17(1-5-21(15)31(29)42)35-18-2-6-22-16(10-18)12-28(57(51,52)53)30(32(22)43)39-37-24-14-20(55(34,46)47)4-8-26(24)41;;;;/h1-14,35,40-43H,(H2,33,44,45)(H2,34,46,47)(H,48,49,50)(H,51,52,53);;;;/q;2*+2;2*+1/p-6/b38-36+,39-37+;;;;
- Substance type: Organic
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
Hardness:
107 mg CaCO3/L
Test temperature:
22.2-23.9 degC
pH:
5.8-6.0
Reference substance (positive control):
not specified
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
129.061 mg/L
Nominal / measured:
estimated
Conc. based on:
not specified
Basis for effect:
growth rate
Remarks on result:
other: Other details not known

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 "f" )  and ("g" and ( not "h") )  )  and ("i" and ( not "j") )  )  and ("k" and ( not "l") )  )  and ("m" and ( not "n") )  )  and ("o" and ( not "p") )  )  and ("q" and "r" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Amine OR Anion OR Aromatic compound OR Azo compound OR Cation OR Secondary amine OR Secondary aromatic amine OR Sulfonamide OR Sulfonic acid derivative by Organic functional groups, Norbert Haider (checkmol) ONLY

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Aliphatic Nitrogen, one aromatic attach [-N] OR Aliphatic Nitrogen, two aromatic attach [-N-] OR Aromatic Carbon [C] OR Azo [-N=N-] OR Miscellaneous metal [Ni, Cu, Zr, Be] OR Miscellaneous sulfide (=S) or oxide (=O) OR Nitrogen, two or tree olefinic attach [>N-] OR Olefinic carbon [=CH- or =C<] OR Oxygen, one aromatic attach [-O-] OR Suflur {v+4} or {v+6} OR Sulfamide, aromatic attach [-SO2-N] OR Sulfonate, aromatic attach [-SO2-O] OR Sulfonyl amide, aromatic attach [-S(=O)N-] OR Sulfur, nitrogen attach [-S-] by Organic functional groups (US EPA) ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Aromatic amine OR Aryl OR Azo OR Fused carbocyclic aromatic OR Overlapping groups OR Phenol OR Sulfonamide OR Sulfonic acid by Organic Functional groups (nested) ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Aromatic amine OR Aryl OR Azo OR Fused carbocyclic aromatic OR Naphtalene OR Phenol OR Sulfonamide OR Sulfonic acid by Organic Functional groups ONLY

Domain logical expression index: "e"

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: "f"

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

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Aromatic amine   [-NH2  or  -NH-] AND Aromatic-H AND Azo group   [-N=N-] AND Benzene AND Four or more fused aromatic rings AND Number of fused 6-carbon aromatic rings AND Number of fused acyclic rings by Bioaccumulation - metabolism alerts

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Triazine ring (symmetric) OR Triazole Ring OR Unsubstituted phenyl group (C6H5-) by Bioaccumulation - metabolism alerts

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Aromatic amine   [-NH2  or  -NH-] AND Aromatic-H AND Azo group   [-N=N-] AND Benzene AND Four or more fused aromatic rings AND Number of fused 6-carbon aromatic rings AND Number of fused acyclic rings by Bioaccumulation - metabolism alerts

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Quaternary amine OR Sulfonic acid / salt -> aliphatic attach OR Sulfonic acid / salt -> aromatic attach by Bioaccumulation - metabolism alerts

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as SHOULD NOT BE PROFILED by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "l"

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

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Aromatic amine   [-NH2  or  -NH-] AND Aromatic-H AND Azo group   [-N=N-] AND Benzene AND Four or more fused aromatic rings AND Number of fused 6-carbon aromatic rings AND Number of fused acyclic rings by Bioaccumulation - metabolism alerts

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Aromatic-CH3 by Bioaccumulation - metabolism alerts

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as Aromatic amine   [-NH2  or  -NH-] AND Aromatic-H AND Azo group   [-N=N-] AND Benzene AND Four or more fused aromatic rings AND Number of fused 6-carbon aromatic rings AND Number of fused acyclic rings by Bioaccumulation - metabolism alerts

Domain logical expression index: "p"

Referential boundary: The target chemical should be classified as -C=CH  [alkenyl hydrogen] by Bioaccumulation - metabolism alerts

Domain logical expression index: "q"

Parametric boundary:The target chemical should have a value of log Kow which is >= -1.79

Domain logical expression index: "r"

Parametric boundary:The target chemical should have a value of log Kow which is <= -0.669

Validity criteria fulfilled:
not specified
Conclusions:
Based on the growth rate inhibition of algae Pseudokirchneriella subcapitata by the chemicaldisodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-), the EC50 was estimated to be 129.06 mg/l.
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 eight closest read across substances, toxicity on Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) was predicted for disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (6798-03-4). Based on the growth rate inhibition of algae Pseudokirchneriella subcapitata by the chemical disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-), the EC50 was estimated to be 129.06 mg/l. Based on this value it can be concluded that the substance disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (6798-03-4) is considered be nontoxic to aquatic environment and cannot be classified as per the criteria mentioned in CLP regulation.    

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 eight closest read across substances, toxicity on Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) was predicted for disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (6798-03-4). Based on the growth rate inhibition of algae Pseudokirchneriella subcapitata by the chemical disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-), the EC50 was estimated to be 129.06 mg/l. Based on this value it can be concluded that the substance disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (6798-03-4) is considered be nontoxic to aquatic environment and cannot be classified as per the criteria mentioned in CLP regulation.    

Key value for chemical safety assessment

EC50 for freshwater algae:
129.06 mg/L

Additional information

Based on the various predicted data for the target chemical and experimental data for structurally and functionally similar read across chemicals study have been reviewed to determine the toxic nature of target chemical disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (6798-03-4) on the growth of aquatic algae and cyanobacteria. The studies are as mentioned below:   

 

In the first prediction for the target chemical disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (6798-03-4) using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the eight closest read across substances, toxicity on Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) was predicted for disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (6798-03-4). Based on the growth rate inhibition of algae Pseudokirchneriella subcapitata by the chemical disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-), the EC50 was estimated to be 129.06 mg/l. Based on this value it can be concluded that the substance disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (6798-03-4) is considered be nontoxic to aquatic environment and cannot be classified as per the criteria mentioned in CLP regulation.   

 

First predicted study was supported by the second experimental weight of evidence study for the read across chemical Amaranth dye (915-67-3) from ABITEC report 2016. Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance 2,7-Naphthalenedisulfonic acid, 3-hydroxy-4-[(4-sulfo-1-naphthalenyl), sodium salt (Amaranth dye) according to OECD Guideline 201. The stock solution (200 mg/L) was prepared by dissolving brown powder in OECD growth medium. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture and tested at the concentrations 0, 12.5, 25, 50, 100, 200 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (ErC50) for the test substance, 2,7-Naphthalenedisulfonic acid, 3-hydroxy-4-[(4-sulfo-1- -naphthalenyl), sodium salt, in Desmodesmus subspicatus was determined to be 356.2 mg/L. This value indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as toxic as per the CLP criteria. 

 

The third study used for another functionally similar read across chemical from the experimental lab report (586/16 report). Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance Disodium 4-hydroxy- 3-[(4-sulphonatonaphthyl)azo]naphthalene-sulphonate according to OECD Guideline 201. The test substance was dissolved in OECD growth medium and tested at the concentrations 0, 2.6, 5.6, 12.0, 27.0, 59.0 and 130 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (ErC50) for the test substance, Disodium 4-hydroxy-3-[(4-sulphonatonaphthyl)azo] naphthalenesulphonate, in Desmodesmus subspicatus was determined to be 265.1 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 4-hydroxy-3-[(4-sulphonatonaphthyl) azo] naphthalenesulphonate does not exhibit toxicity to aquatic algae (Desmodesmus subspicatus).

 

Similar classification was also observed for the most structurally similar read across chemical (2519-30-4) from the experimental test report 444/16. Short term toxicity study of Tetrasodium 1-acetamido-2-hydroxy-3-(4-((4-sulphonatophenylazo)-7-sulphonato-1-naphthylazo))naphthalene-4,6-disulphonate (Brilliant black 1) to aquatic algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) was conducted for 72 hrs. Test was performed according to the 201 OECD guideline in a static system. The stock solution 100 mg/l was prepared by dissolving black powder in OECD growth medium. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture and tested at the 0, 12, 20, 35, 60, 100 mg/l nominal concentrations. Effects on the growth rate of the organism were studied. Potassium dichromate (K2Cr2O7) were used as a reference positive control. Effects on growth rate were observed for 72 hours by using nonlinear regression by the software Prism 4.0. Based on the growth rate inhibition of test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the chemical Tetrasodium 1-acetamido-2-hydroxy- 3-(4-((4-sulphonatophenylazo)- 7-sulphonato -1-naphthylazo)) naphthalene-4,6-disulphonate (Brilliant black 1), the effect concentration ErC50 was 76.8 mg/l. This value indicates that the substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 3 as per the CLP criteria. But as the chemical was readily biodegradable in water so on that basis chemical was consider as nontoxic and can be consider to be not classified as per the CLP classification criteria.

 

Based on the predicted data for the target chemical (from OECD QSAR 2018) and for the read across chemical from experimental lab reports (ABITEC reports), it can be concluded that the substance disodium [μ-[[7,7'-iminobis[4-hydroxy-3-[[2-hydroxy-5-sulphamoylphenyl]azo] naphthalene-2-sulphonato]](6-)]]dicuprate(2-) (6798-03-4) is considered to be not toxic to aquatic environment (aquatic algae and cyanobacteria) and cannot be classified as toxic as per the criteria mentioned in CLP regulation.