1-phenylazo-2-naphthol

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

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.

Qualifier:

no guideline available

Principles of method if other than guideline:

Prediction is done using OECD QSAR Toolbox version 3.3 with log Kow as the primary descriptor.

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material: 1-phenylazo-2-naphthol
- Molecular formula: C16 H12 N2 O
- Molecular weight: 248.284 g/mol
- Smiles notation: c12c(\N=N\c3ccccc3)c(ccc1cccc2)O
- InChl: 1S/C16H12N2O/c19-15-11-10-12-6-4-5-9-14(12)16(15)18-17-13-7-2-1-3-8-13/h1-11,19H/b18-17+
- Substance type: Organic
- Physical state: Solid

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Test temperature:

25 degC

pH:

6.9

Reference substance (positive control):

not specified

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

366.43 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Sublethal observations / clinical signs:

The prediction was based on dataset comprised from the following descriptors: LC50
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("g" and(not "h")) ) and("i" and(not "j")) ) and "k") and "l") and("m" and(not "n")) ) and("o" and "p") )

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 Phenols by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "d"

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

Domain logical expression index: "e"

Referential boundary:The target chemical should be classified as Moderate binder, NH2 group OR Moderate binder, OH grooup OR Non binder, impaired OH or NH2 group OR Non binder, MW>500 OR Non binder, non cyclic structure OR Non binder, without OH or NH2 group OR Strong binder, NH2 group OR Very strong binder, OH group OR Weak binder, NH2 group OR Weak binder, OH group by Estrogen Receptor Binding

Domain logical expression index: "f"

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

Domain logical expression index: "g"

Referential boundary:The target chemical should be classified as No alert found by Protein binding alerts for Chromosomal aberration by OASIS v1.1

Domain logical expression index: "h"

Referential boundary:The target chemical should be classified as Ac-SN2 OR Ac-SN2 >> Acylation involving an activated (glucuronidated) carboxamide group OR Ac-SN2 >> Acylation involving an activated (glucuronidated) carboxamide group >> Carboxylic Acid Amines OR Ac-SN2 >> Direct acylation involving a leaving group OR Ac-SN2 >> Direct acylation involving a leaving group >> Carboxylic Acid Amines OR AN2 OR AN2 >> Michael addition to the quinoid type structures OR AN2 >> Michael addition to the quinoid type structures >> N-Subsituted Aromatic Amines OR AN2 >> Michael-type addition to quinoid structures OR AN2 >> Michael-type addition to quinoid structures >> Carboxylic Acid Amines OR AN2 >> Michael-type addition to quinoid structures >> Phenols by Protein binding alerts for Chromosomal aberration by OASIS v1.1

Domain logical expression index: "i"

Referential boundary:The target chemical should be classified as No alert found by rtER Expert System ver.1 - USEPA

Domain logical expression index: "j"

Referential boundary:The target chemical should be classified as Phenylphenols by rtER Expert System ver.1 - USEPA

Domain logical expression index: "k"

Referential boundary:The target chemical should be classified as Not bioavailable by Lipinski Rule Oasis ONLY

Domain logical expression index: "l"

Similarity boundary:Target: Oc1ccc2ccccc2c1N=Nc1ccccc1
Threshold=60%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "m"

Referential boundary:The target chemical should be classified as Arylazo Type Compounds AND Phenol Type Compounds by Oncologic Primary Classification

Domain logical expression index: "n"

Referential boundary:The target chemical should be classified as Acrylamide Reactive Functional Groups OR Aromatic Amine Type Compounds OR C-Nitroso and Oxime Type Compounds OR Halogenated Aromatic Hydrocarbon Type Compounds by Oncologic Primary Classification

Domain logical expression index: "o"

Parametric boundary:The target chemical should have a value of log Kow which is >= 5.04

Domain logical expression index: "p"

Parametric boundary:The target chemical should have a value of log Kow which is <= 6.96

Validity criteria fulfilled:

not specified

Conclusions:

The median lethal concentration (LC50) for the test substance, 1-phenylazo-2-naphthol, in Danio rerio on the basis of mortality effect was estimated to be 366.43 mg/L.

Executive summary:

A study was predicted using OECD QSAR toolbox version 3.3 (2017); to assess the toxicity effect of 1-phenylazo-2-naphthol on fish in a 96 hours of exposure. The median lethal concentration (LC50) for the test substance, 1-phenylazo-2-naphthol, in Danio rerio on the basis of mortality effect was estimated to be 366.43 mg/L. Thus, on the basis of this LC50 value and according to CLP Criteria for aquatic classification of the substance, it is concluded that 1-phenylazo- 2-naphthol (CAS no. 842 -07 -9) does not exhibit short term toxicity to fish.

Description of key information

A study was predicted using OECD QSAR toolbox version 3.3 (2017); to assess the toxicity effect of 1-phenylazo-2-naphthol on fish in a 96 hours of exposure. The median lethal concentration (LC50) for the test substance, 1-phenylazo-2-naphthol, in Danio rerio on the basis of mortality effect was estimated to be 366.43 mg/L. Thus, on the basis of this LC50 value and according to CLP Criteria for aquatic classification of the substance, it is concluded that 1-phenylazo- 2-naphthol (CAS no. 842 -07 -9) does not exhibit short term toxicity to fish.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

366.43 mg/L

Additional information

Various studies including experimental data and predicted results from validated model for toxicity to aquatic fish with the target substance 1-phenylazo-2- naphthol (CAS No. 842-07-9) and to its relevant read across substance 9-(2-carboxyphenyl)-3,6-bis(diethylamino)xanthylium chloride (CAS No.- 81-88-9) by considering its structure-activity relationships, were summarized as follows: 

  

A study was predicted using OECD QSAR toolbox version 3.3 (2017); to assess the toxicity effect of 1-phenylazo-2-naphthol on fish in a 96 hours of exposure. The median lethal concentration (LC50) for the test substance, 1-phenylazo-2-naphthol, in Danio rerio on the basis of mortality effect was estimated to be 366.43 mg/L.

 

Moreover, in a study conducted by Marking,L.L. (Prog. Fish-Cult.31(3): 139-142, 1969),to assess the toxic effects of the test compound 9-(2-carboxyphenyl)-3, 6-bis(diethylamino)xanthylium chloride on the Lepomis macrochirus (Bluegill) in a 96 hours of exposure. The lethal concentrations (LC50) for the test substance, 9-(2-carboxyphenyl)-3,6-bis(diethylamino)xanthylium chloride, in fish (Lepomis macrochirus) on a mortality effect was observed to be 379 (260 - 554) mg/L.

 

So, based on the above predicted and experimental studies for target substance 1-phenylazo- 2-naphthol (CAS no. 842 -07 -9) and to its read across substance, the lethal concentration LC50 value was found to be in the range of 366.43 mg/L to 379 mg/L. Thus, on the basis of this LC50 value and according to CLP Criteria for aquatic classification of the substance, it is concluded that 1-phenylazo- 2-naphthol (CAS no. 842 -07 -9) does not exhibit short term toxicity to fish.

Although this value suggests that the substance is not classified in short term toxicity to fish, since it is classified in Aquatic chronic category 4 as per the Harmonised classification - Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation), the same has been considered for the dossier.