Sodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

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

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): Sodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonate
- Common name: Acid Red 151
- Molecular formula: C22H15N4O4S.Na
- Molecular weight: 455.448 g/mol
-Physical state: red to brown powder
- Smiles notation: c12c(\N=N\c3ccc(\N=N\c4ccc(S(O)(=O)=O)cc4)cc3)c(ccc1cccc2)O.[Na+]
- InChl: 1S/C22H16N4O4S.Na/c27-21-14-5-15-3-1-2-4-20(15)22(21)26-25-17-8-6-16(7-9-17)23-24-18-10-12-19(13-11-18)31(28,29)30;/h1-14,27H,(H,28,29,30);/q;+1/b24-23+,26-25+;
- Substance type: Organic

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella 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.:

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

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as SN1 AND SN1 >> Nitrenium Ion formation AND SN1 >> Nitrenium Ion formation >> Aromatic azo by DNA binding by OECD

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 Acid moiety AND Phenols AND Salt by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OASIS v.1.4

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as AN2 >> Shiff base formation after aldehyde release >> Specific Acetate Esters by DNA binding by OASIS v.1.4

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OASIS v.1.4

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as AN2 by DNA binding by OASIS v.1.4

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OASIS v1.4

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Acylation >> Acylation involving an activated (glucuronidated) ester group by Protein binding by OASIS v1.4

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OASIS v1.4

Domain logical expression index: "k"

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

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OASIS v1.4

Domain logical expression index: "m"

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

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as High (Class III) by Toxic hazard classification by Cramer (extension) ONLY

Domain logical expression index: "o"

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: "p"

Referential boundary: The target chemical should be classified as Vinyl/Allyl Alcohols by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "q"

Parametric boundary:The target chemical should have a value of log Kow which is >= 0.495

Domain logical expression index: "r"

Parametric boundary:The target chemical should have a value of log Kow which is <= 5.38

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 sodium 4-({4-[(2-hydroxy-1-naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0). EC50 growth rate value value was estimated to be 116.059 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that sodium 4-({4-[(2-hydroxy-1 naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0) 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 sodium 4-({4-[(2-hydroxy-1-naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0). EC50 growth rate value value was estimated to be 116.059 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that sodium 4-({4-[(2-hydroxy-1 naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0) 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 sodium 4-({4-[(2-hydroxy-1-naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0). EC50 growth rate value value was estimated to be 116.059 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that sodium 4-({4-[(2-hydroxy-1 naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0) was likely to be not toxic to aquatic algae.

Key value for chemical safety assessment

EC50 for freshwater algae:

116.059 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 sodium 4-({4-[(2-hydroxy-1 naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0) 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 sodium 4-({4-[(2-hydroxy-1-naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0). EC50 growth rate value value was estimated to be 116.059 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that sodium 4-({4-[(2-hydroxy-1 naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0) 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

disodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonatE(CAS: 2783 -94 -0) from the ABITEC Lab report 2016, suggests that the

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substancedisodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonateaccording to OECD Guideline 201.

The test substance was dissolved in DMSO and tested at the concentrations 0, 17, 30, 55, 100 and 185 mg/L. Effects on the growth rate of the organism were studied.

The median effective concentration (EC50) for the test substance,disodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonate, in Desmodesmus subspicatus was determined to be 113.2 mg/L.

This value indicates that the substance is not likely to be hazardous to aquatic algae as per the CLP criteria.

Another supporting experimental study for the structurally similar read across Disodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonate (CAS: 3567-66-6 from the ABITEC Lab report 2016, also suggests that the Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substanceDisodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonateaccording to OECD Guideline 201.

The test substance was dissolved in OECD growth medium and tested at the concentrations12.5, 25.0, 50.0, 100.0, 200.0 mg/L. Effects on the growth rate of the organism were studied.

The median effective concentration (EC50) 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 on the basis of effects on growth rate in a 72 hour study.

This value indicates that the substance is likely to be non-hazardous to aquatic algae and can be classified as "not classified" as per the CLP criteria.

Thus based on the effect concentrations which is in the range 113.2 mg/l to 330.2 mg/l give the conclusion that test substance sodium 4-({4-[(2-hydroxy-1 naphthyl)diazenyl]phenyl}diazenyl)benzenesulfonate (CAS: 6406-56-0) 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.