Registration Dossier

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, gene mutation was predicted for 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid. The study assumed the use of Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 with S9 metabolic activation system. 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid was predicted to not induce gene mutation in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 in the presence of S9 metabolic activation system and hence, according to the prediction made, it is not likely to classify as a gene mutant in vitro.

Based on the predicted result it can be concluded that the substance is considered to not toxic as per the criteria mentioned in CLP regulation.

Reference

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

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 3.4 and the supporting QMRF report has been attached

Qualifier:

according to guideline

Guideline:

other: Refer below principle

Principles of method if other than guideline:

Prediction is done using OECD QSAR Toolbox version 3.4, 2018

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Specific details on test material used for the study:

- Name of test material: m-(4,5-dihydro-5-imino-3-methyl-1H-pyrazol-1-yl)benzenesulphonic acid
- IUPAC name: 3-(5-imino-3-methyl-4,5-dihydro-1H-pyrazol-1-yl)benzene-1-sulfonic acid
- Molecular formula: C10H11N3O3S
- Molecular weight: 253.281 g/mole
- Smiles: O=S(=O)(O)c1cccc(N2N=C(CC2=N)C)c1
- Inchl: 1S/C10H11N3O3S/c1-7-5-10(11)13(12-7)8-3-2-4-9(6-8)17(14,15)16/h2-4,6,11H,5H2,1H3,(H,14,15,16)
- Substance type: Organic

Target gene:

Histidine

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Details on mammalian cell type (if applicable):

Not applicable

Additional strain / cell type characteristics:

not specified

Cytokinesis block (if used):

No data

Metabolic activation:

with

Metabolic activation system:

S9 metabolic activation system

Test concentrations with justification for top dose:

No data

Vehicle / solvent:

No data

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

not specified

True negative controls:

not specified

Positive controls:

not specified

Positive control substance:

not specified

Details on test system and experimental conditions:

No data

Rationale for test conditions:

No data

Evaluation criteria:

Prediction is done considering a dose dependent increase in the number of revertants/plate

Statistics:

No data

Species / strain:

S. typhimurium, other: TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Additional information on results:

No data

Remarks on result:

no mutagenic potential (based on QSAR/QSPR prediction)

The prediction was based on dataset comprised from the following descriptors: "Gene mutation"
Estimation method: Takes highest mode value from the 6 nearest neighbours
Domain logical expression:Result: In Domain

(((((((((((("a" or "b" or "c" or "d" ) and ("e" and ( not "f") ) ) and ("g" and ( not "h") ) ) and ("i" and ( not "j") ) ) and ("k" and ( not "l") ) ) and "m" ) and ("n" and ( not "o") ) ) and ("p" and ( not "q") ) ) and ("r" and ( not "s") ) ) and ("t" and ( not "u") ) ) and ("v" and ( not "w") ) ) and ("x" and "y" ) )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Aromatic compound OR Heterocyclic compound OR Sulfonic acid 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 Carbon [CH] OR Aliphatic Carbon [-CH2-] OR Aliphatic Carbon [-CH3] OR Aliphatic Nitrogen, one aromatic attach [-N] OR Aromatic Carbon [C] OR Azomethine, aliphatic attach [-N=C] OR Hydrazine [>N-N<] OR Hydroxy, sulfur attach [-OH] OR Miscellaneous sulfide (=S) or oxide (=O) OR Nitrogen, two or tree olefinic attach [>N-] OR Olefinic carbon [=CH- or =C<] OR Suflur {v+4} or {v+6} OR Sulfinic acid [-S(=O)OH] OR Sulfonate, aromatic attach [-SO2-O] by Organic functional groups (US EPA) ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Amidine OR Aryl OR Overlapping groups OR Sulfonic acid OR Unsaturated heterocyclic amine OR Unsaturated heterocyclic fragment by Organic Functional groups (nested) ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Amidine OR Aryl OR Sulfonic acid OR Unsaturated heterocyclic amine OR Unsaturated heterocyclic fragment by Organic Functional groups 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 Acylation OR Acylation >> P450 Mediated Activation to Isocyanates or Isothiocyanates OR Acylation >> P450 Mediated Activation to Isocyanates or Isothiocyanates >> Formamides OR Michael addition OR Michael addition >> P450 Mediated Activation of Heterocyclic Ring Systems OR Michael addition >> P450 Mediated Activation of Heterocyclic Ring Systems >> Furans OR Michael addition >> P450 Mediated Activation of Heterocyclic Ring Systems >> Thiophenes-Michael addition OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> 3-Methylindole derivatives OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Arenes OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Polycyclic (PAHs) and heterocyclic (HACs) aromatic hydrocarbons-Michael addition OR Michael addition >> Polarised Alkenes-Michael addition OR Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated aldehydes OR Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated ketones OR Michael addition >> Quinones and Quinone-type Chemicals OR Michael addition >> Quinones and Quinone-type Chemicals >> Quinones OR Schiff base formers OR Schiff base formers >> Chemicals Activated by P450 to Mono-aldehydes OR Schiff base formers >> Chemicals Activated by P450 to Mono-aldehydes >> Thiazoles OR Schiff base formers >> Direct Acting Schiff Base Formers OR Schiff base formers >> Direct Acting Schiff Base Formers >> Alpha-beta-dicarbonyl OR SN1 OR SN1 >> Carbenium Ion Formation OR SN1 >> Carbenium Ion Formation >> Allyl benzenes OR SN1 >> Carbenium Ion Formation >> Hydrazine OR SN1 >> Carbenium Ion Formation >> N-Nitroso (alkylation) OR SN1 >> Carbenium Ion Formation >> Polycyclic (PAHs) and heterocyclic (HACs) aromatic hydrocarbons-SN1 OR SN1 >> Carbenium Ion Formation >> Triazenes OR SN1 >> Iminium Ion Formation OR SN1 >> Iminium Ion Formation >> Aliphatic tertiary amines OR SN1 >> Nitrenium Ion formation OR SN1 >> Nitrenium Ion formation >> Aromatic azo OR SN1 >> Nitrenium Ion formation >> Aromatic N-hydroxylamines OR SN1 >> Nitrenium Ion formation >> Aromatic nitro OR SN1 >> Nitrenium Ion formation >> Primary (unsaturated) heterocyclic amine OR SN1 >> Nitrenium Ion formation >> Primary aromatic amine OR SN1 >> Nitrenium Ion formation >> Tertiary aromatic amine OR SN1 >> Nitrenium Ion formation >> Unsaturated heterocyclic nitro OR SN1 >> Nitrosation-SN1 OR SN1 >> Nitrosation-SN1 >> N-Nitroso-SN1 OR SN2 OR SN2 >> Direct Acting Epoxides and related OR SN2 >> Direct Acting Epoxides and related >> Aziridines OR SN2 >> Direct Acting Epoxides and related >> Epoxides OR SN2 >> Direct Acting Epoxides and related >> Sulfuranes OR SN2 >> Nitrosation-SN2 OR SN2 >> Nitrosation-SN2 >> Nitroso-SN2 OR SN2 >> P450 Mediated Epoxidation OR SN2 >> P450 Mediated Epoxidation >> Thiophenes-SN2 OR SN2 >> SN2 at an sp3 Carbon atom OR SN2 >> SN2 at an sp3 Carbon atom >> Sulfonates by DNA binding by OECD

Domain logical expression index: "g"

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

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> Acylation involving an activated (glucuronidated) sulfonamide group OR Acylation >> Acylation involving an activated (glucuronidated) sulfonamide group >> Arenesulfonamides OR Acylation >> Ester aminolysis OR Acylation >> Ester aminolysis >> Dithiocarbamates OR AN2 OR AN2 >> Michael addition to activated double bonds OR AN2 >> Michael addition to activated double bonds >> alpha,beta-Unsaturated Carbonyls and Related Compounds OR AN2 >> Michael-type addition to activated double bonds in vinyl pyridines OR AN2 >> Michael-type addition to activated double bonds in vinyl pyridines >> Ethenyl Pyridines OR AN2 >> Michael-type addition to quinoid structures OR AN2 >> Michael-type addition to quinoid structures >> N-Substituted Aromatic Amines OR AN2 >> Michael-type addition to quinoid structures >> Quinoneimine OR AN2 >> Michael-type addition to quinoid structures >> Substituted Anilines OR AN2 >> Nucleophilic addition at polarized N-functional double bond OR AN2 >> Nucleophilic addition at polarized N-functional double bond >> Arenesulfonamides OR AN2 >> Nucleophilic addition to pyridonimine tautomer of aminopyridoindoles or aminopyridoimidazoles (hypothesized) OR AN2 >> Nucleophilic addition to pyridonimine tautomer of aminopyridoindoles or aminopyridoimidazoles (hypothesized) >> Heterocyclic Aromatic Amines OR AR OR AR >> Radical-type addition to imino tautomer of aminoacridines OR AR >> Radical-type addition to imino tautomer of aminoacridines >> Benzoquinoline and Аcridine derivatives OR Michael addition OR Michael addition >> Michae addition on quinoide type compounds OR Michael addition >> Michae addition on quinoide type compounds >> Quinone methide(s)/imines; Quinoide oxime structure; Nitroquinones, Naphthoquinone(s)/imines OR Michael addition >> Michael addition on alpha,beta-Unsaturated carbonyl compounds OR Michael addition >> Michael addition on alpha,beta-Unsaturated carbonyl compounds >> alpha,beta-Aldehydes OR Michael addition >> Michael addition on conjugated systems with electron withdrawing group OR Michael addition >> Michael addition on conjugated systems with electron withdrawing group >> Conjugated systems with electron withdrawing groups OR Michael addition >> Michael addition on conjugated systems with electron withdrawing group >> Cyanoalkenes OR Michael addition >> Michael addition on conjugated systems with electron withdrawing group >> Nitroalkenes OR Michael addition >> Michael addition on polarised Alkenes OR Michael addition >> Michael addition on polarised Alkenes >> alpha,beta-Unsaturated oximes OR Michael addition >> Michael addition on polarised Alkenes >> Polarised Alkene - alkenyl pyridines, pyrazines, pyrimidines or triazines OR Michael addition >> Michael type addition on quinone type chemicals OR Michael addition >> Michael type addition on quinone type chemicals >> Pyranones, Pyridones (and related nitrogen chemicals) OR Nucleophilic addition OR Nucleophilic addition >> Addition to carbon-hetero double bonds OR Nucleophilic addition >> Addition to carbon-hetero double bonds >> Azomethyme type compounds OR Nucleophilic addition >> Addition to carbon-hetero double bonds >> Ketones OR Radical reactions OR Radical reactions >> ROS generation and direct attack of hydroxyl radical to the C8 position of nucleoside base OR Radical reactions >> ROS generation and direct attack of hydroxyl radical to the C8 position of nucleoside base >> Heterocyclic Aromatic Amines OR Schiff base formation OR Schiff base formation >> Direct acting Schiff base formers OR Schiff base formation >> Direct acting Schiff base formers >> 1,2-Dicarbonyls and 1,3-Dicarbonyls OR Schiff base formation >> Schiff base formation with carbonyl compounds OR Schiff base formation >> Schiff base formation with carbonyl compounds >> Aldehydes OR SE reaction (CYP450-activated heterocyclic amines) OR SE reaction (CYP450-activated heterocyclic amines) >> Direct attack of arylnitrenium cation to the C8 position of nucleoside base OR SE reaction (CYP450-activated heterocyclic amines) >> Direct attack of arylnitrenium cation to the C8 position of nucleoside base >> Heterocyclic Aromatic Amines OR SN1 OR SN1 >> DNA and protein alkylation via the formation of alkyldiazonium ion OR SN1 >> DNA and protein alkylation via the formation of alkyldiazonium ion >> N-Nitrosoamine Derivatives OR SN2 OR SN2 >> DNA and protein alkylation via the formation of alkyldiazonium ion OR SN2 >> DNA and protein alkylation via the formation of alkyldiazonium ion >> N-Nitrosoamine Derivatives OR SN2 >> Interchange reaction with sulphur containing compounds OR SN2 >> Interchange reaction with sulphur containing compounds >> Thiols and disulfide compounds OR SN2 >> Ring opening nucleophilic substitution involving arene oxide derivatives and proteins OR SN2 >> Ring opening nucleophilic substitution involving arene oxide derivatives and proteins >> Benzoquinoline and Аcridine derivatives OR SNAr OR SNAr >> Nucleophilic substitution on activated Csp2-atoms in quinolines OR SNAr >> Nucleophilic substitution on activated Csp2-atoms in quinolines >> Benzoquinoline and Аcridine derivatives OR SR reaction (peroxidase-activated heterocyclic amines) OR SR reaction (peroxidase-activated heterocyclic amines) >> Direct attack of arylnitrenium radical to the C8 position of nucleoside base OR SR reaction (peroxidase-activated heterocyclic amines) >> Direct attack of arylnitrenium radical to the C8 position of nucleoside base >> Heterocyclic Aromatic Amines by Protein binding by OASIS v1.4

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OECD

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as SN2 OR SN2 >> SN2 reaction at sp3 carbon atom OR SN2 >> SN2 reaction at sp3 carbon atom >> Sulfonates by Protein binding by OECD

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as (!Undefined)Group All Lipid Solubility < 0.01 g/kg AND Group All Melting Point > 200 C AND Group CNS Melting Point > 200 C AND Group CNS Melting Point > 50 C by Eye irritation/corrosion Exclusion rules by BfR

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as (!Undefined)Group All Aqueous Solubility < 0.000005 g/L OR (!Undefined)Group All Aqueous Solubility < 0.00002 g/L OR (!Undefined)Group All log Kow < -3.1 OR (!Undefined)Group All log Kow > 9 OR (!Undefined)Group All Melting Point > 200 C OR (!Undefined)Group CN Aqueous Solubility < 0.1 g/L OR (!Undefined)Group CN Lipid Solubility < 0.4 g/kg OR (!Undefined)Group CN log Kow > 4.5 OR (!Undefined)Group CNHal Lipid Solubility < 400 g/kg OR (N/A) OR Exclusion rules not met OR Group All Aqueous Solubility < 0.000005 g/L OR Group All Aqueous Solubility < 0.00002 g/L OR Group All log Kow < -3.1 OR Group All log Kow > 9 OR Group C Aqueous Solubility < 0.0001 g/L OR Group C Aqueous Solubility < 0.0005 g/L OR Group C Melting Point > 55 C OR Group C Molecular Weight > 380 g/mol OR Group CN Aqueous Solubility < 0.1 g/L OR Group CN log Kow > 4.5 OR Group CN Molecular Weight > 290 g/mol OR Group CNS log Kow < -2 OR Group CNS log Kow > 1.5 by Eye irritation/corrosion Exclusion rules by BfR

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Bioavailable by Lipinski Rule Oasis ONLY

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Amidine AND Aryl AND Sulfonic acid AND Unsaturated heterocyclic amine AND Unsaturated heterocyclic fragment by Organic Functional groups

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as Alkane, branched with tertiary carbon OR Alkene OR Alkyl by Organic Functional groups

Domain logical expression index: "p"

Referential boundary: The target chemical should be classified as Amidine AND Aryl AND Sulfonic acid AND Unsaturated heterocyclic amine AND Unsaturated heterocyclic fragment by Organic Functional groups

Domain logical expression index: "q"

Referential boundary: The target chemical should be classified as Tin, organo by Organic Functional groups

Domain logical expression index: "r"

Referential boundary: The target chemical should be classified as Amidine AND Aryl AND Sulfonic acid AND Unsaturated heterocyclic amine AND Unsaturated heterocyclic fragment by Organic Functional groups

Domain logical expression index: "s"

Referential boundary: The target chemical should be classified as N-Oxide by Organic Functional groups

Domain logical expression index: "t"

Referential boundary: The target chemical should be classified as Amidine AND Aryl AND Sulfonic acid AND Unsaturated heterocyclic amine AND Unsaturated heterocyclic fragment by Organic Functional groups

Domain logical expression index: "u"

Referential boundary: The target chemical should be classified as Naphtalene by Organic Functional groups

Domain logical expression index: "v"

Referential boundary: The target chemical should be classified as Amidine AND Aryl AND Sulfonic acid AND Unsaturated heterocyclic amine AND Unsaturated heterocyclic fragment by Organic Functional groups

Domain logical expression index: "w"

Referential boundary: The target chemical should be classified as Melamine by Organic Functional groups

Domain logical expression index: "x"

Parametric boundary:The target chemical should have a value of log Kow which is >= -2.4

Domain logical expression index: "y"

Parametric boundary:The target chemical should have a value of log Kow which is <= -1.02

Conclusions:

4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid was predicted to not induce gene mutation in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 in the presence of S9 metabolic activation system and hence, according to the prediction made, it is not likely to classify as a gene mutant in vitro.

Executive summary:

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, gene mutation was predicted for 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid. The study assumed the use of Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 with S9 metabolic activation system. 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid was predicted to not induce gene mutation in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 in the presence of S9 metabolic activation system and hence, according to the prediction made, it is not likely to classify as a gene mutant in vitro.

Based on the predicted result it can be concluded that the substance is considered to not toxic as per the criteria mentioned in CLP regulation.

Endpoint conclusion:

no adverse effect observed (negative)

Endpoint conclusion:

no study available

Gene mutation in vitro:

Prediction model based estimation and data from read across chemicals have been reviewed to determine the mutagenic nature of

4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid. The studies are as summarized below:

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, gene mutation was predicted for 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid. The study assumed the use of Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 with and without S9 metabolic activation system. 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid was predicted to not induce gene mutation in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 in the presence and absence of S9 metabolic activation system and hence, according to the prediction made, it is not likely to classify as a gene mutant in vitro.

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, chromosomal aberration was predicted for 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid. The study assumed the use of Chinese hamster ovary (CHO) cell line with and without S9 metabolic activation system. 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid was predicted to not induce chromosomal aberrations in Chinese hamster ovary (CHO) cell line in the presence and absence of S9 metabolic activation system and hence, according to the prediction made, it is not likely to classify as a gene mutant in vitro.

Gene mutation toxicity was predicted for 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid using the battery approach from Danish QSAR database (2018). The study assumed the use of Salmonella typhimurium bacteria in the Ames test. The end point for gene mutation has been modeled in the Danish QSAR using the three software systems Leadscope, CASE Ultra and SciQSAR. Based on predictions from these three systems, a fourth and overall battery prediction is made. The battery prediction is made using the so called Battery algorithm. With the battery approach it is in many cases possible to reduce “noise” from the individual model estimates and thereby improve accuracy and/or broaden the applicability domain. Gene mutation toxicity study as predicted by Danish QSAR for 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid is negative and hence the chemical is predicted to not classify as a gene mutant in vitro.

The predicted data is further supported by data from read across chemical.

Bacterial gene mutation assay was performed by Chung et al (Applied and Environmental Microbiology, 1981) to evaluate the mutagenic nature of 60 -70% struturally and functionally similar read across chemical Pyrazolone T (RA CAS no 118 -47 -8) by the plate incorporation method. The test was performed using Salmonella typhimurium tester strains TA1535, TA1537, TA1538, TA98, and TA100 with and without S9 activation system. After the treatment , the revertant colonies were counted by using a hand-held tally. The test compound was dissolved in DMSO and used at dose levels of 5 to 5000 µg. Pyrazolone T did not induce gene mutation in the Salmonella typhimurium tester strains TA1535, TA1537, TA1538, TA98, and TA100 with and without S9 activation system and hence is negative for gene mutation in vitro.

Zeiger et al (Environmental and Molecular Mutagenesis, 1988) also performed Salmonella/microsome test in the absence of exogenous metabolic activation and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters to evaluate the mutagenic nature of 60 -70% structurally and functionally similar read across chemical 1-Phenyl-3- Methyl-5- Pyrazolone (RA CAS no 89 -25 -8). The test compound was dissolved in DMSO and used at a dosage level of 0, 100, 333, 1000, 3333.0, 6666.0, 10000 µg/plate in the preincubation assay of 48 hrs. Concurrent solvent abd positive control chemicals were also included in the study. 1-Phenyl-3- Methyl-5- Pyrazolone did not induce gene mutation in the S. typhimurium tester strains TA 1535, TA 1537, TA 98 and TA 100 in the presence and absence of S9 metabolic activation system and hence it is negative for gene mutation in vitro.

Based on the data available for the target chemical and its read across, 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid does not exhibit gene mutation in vitro. Hence the test chemical is not likely to classify as a gene mutant in vitro.

Based on the data available for the target chemical and its read across, 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichlorobenzenesulphonic acid (CAS no 68083 -38 -5) does not exhibit gene mutation in vitro. Hence the test chemical is not likely to classify as a gene mutant in vitro