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Genetic toxicity in vitro

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 five closest read across substances, gene mutation was predicted for 4-methoxy-2-methyl-N-phenylaniline. 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-methoxy-2-methyl-N-phenylaniline 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.

Link to relevant study records
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 3.3 and the supporting QMRF report has been attached
Qualifier:
according to guideline
Guideline:
other: Refer below priinciple
Principles of method if other than guideline:
Prediction is done using OECD QSAR Toolbox version 3.3, 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: 4-methoxy-2-methyl-N-phenylaniline
- IUPAC name: 4-methoxy-2-methyl-N-phenylaniline
- Molecular formula: C14H15NO
- Molecular weight: 213.279 g/mol
- Smiles: c1(c(cc(cc1)OC)C)Nc1ccccc1
- InChl: 1S/C14H15NO/c1-11-10-13(16-2)8-9-14(11)15-12-6-4-3-5-7-12/h3-10,15H,1-2H3
- Substance type: Organic
Target gene:
Histidine
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
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, TA 100 and TA 102
Metabolic activation:
without
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 11 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 ( not "n") )  )  and ("o" and ( not "p") )  )  and ("q" and ( not "r") )  )  and "s" )  and ("t" and "u" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Alkylarylether OR Amine OR Aromatic compound OR Ether OR Secondary amine OR Secondary aromatic amine 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, two aromatic attach [-N-] OR Aromatic Carbon [C] OR Nitrogen, two or tree olefinic attach [>N-] OR Olefinic carbon [=CH- or =C<] OR Oxygen, one aromatic attach [-O-] by Organic functional groups (US EPA) ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Alkyl arenes OR Aromatic amine OR Ether OR Overlapping groups OR Precursors quinoid compounds by Organic Functional groups (nested) ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Alkyl arenes OR Aromatic amine OR Aryl OR Ether OR Precursors quinoid compounds 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 OASIS v.1.3

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as AN2 OR AN2 >>  Michael-type addition, quinoid structures OR AN2 >>  Michael-type addition, quinoid structures >> Quinones OR AN2 >> Carbamoylation after isocyanate formation OR AN2 >> Carbamoylation after isocyanate formation >> N-Hydroxylamines OR AN2 >> Nucleophilic addition to alpha, beta-unsaturated carbonyl compounds OR AN2 >> Nucleophilic addition to alpha, beta-unsaturated carbonyl compounds >> alpha, beta-Unsaturated Aldehydes OR AN2 >> Schiff base formation OR AN2 >> Schiff base formation >> alpha, beta-Unsaturated Aldehydes OR Michael addition OR Michael addition >> Quinone type compounds OR Michael addition >> Quinone type compounds >> Quinone methides OR Non-covalent interaction OR Non-covalent interaction >> DNA intercalation OR Non-covalent interaction >> DNA intercalation >> Acridone, Thioxanthone, Xanthone and Phenazine Derivatives OR Non-covalent interaction >> DNA intercalation >> Aminoacridine DNA Intercalators OR Non-covalent interaction >> DNA intercalation >> Fused-Ring Primary Aromatic Amines OR Non-covalent interaction >> DNA intercalation >> Quinones OR Radical OR Radical >> Radical mechanism by ROS formation OR Radical >> Radical mechanism by ROS formation >> Acridone, Thioxanthone, Xanthone and Phenazine Derivatives OR Radical >> Radical mechanism via ROS formation (indirect) OR Radical >> Radical mechanism via ROS formation (indirect) >> C-Nitroso Compounds OR Radical >> Radical mechanism via ROS formation (indirect) >> Conjugated Nitro Compounds OR Radical >> Radical mechanism via ROS formation (indirect) >> Fused-Ring Primary Aromatic Amines OR Radical >> Radical mechanism via ROS formation (indirect) >> Hydrazine Derivatives OR Radical >> Radical mechanism via ROS formation (indirect) >> N-Hydroxylamines OR Radical >> Radical mechanism via ROS formation (indirect) >> Quinones OR Radical >> Radical mechanism via ROS formation (indirect) >> Single-Ring Substituted Primary Aromatic Amines OR Radical >> ROS formation after GSH depletion OR Radical >> ROS formation after GSH depletion >> Quinone methides OR SN1 OR SN1 >> Alkylation after metabolically formed carbenium ion species OR SN1 >> Alkylation after metabolically formed carbenium ion species >> Polycyclic Aromatic Hydrocarbon Derivatives OR SN1 >> Nucleophilic attack after carbenium ion formation OR SN1 >> Nucleophilic attack after carbenium ion formation >> Acyclic Triazenes OR SN1 >> Nucleophilic attack after carbenium ion formation >> N-Nitroso Compounds OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Fused-Ring Primary Aromatic Amines OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> N-Hydroxylamines OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Single-Ring Substituted Primary Aromatic Amines OR SN1 >> Nucleophilic attack after nitrenium and/or carbenium ion formation OR SN1 >> Nucleophilic attack after nitrenium and/or carbenium ion formation >> N-Nitroso Compounds OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Conjugated Nitro Compounds OR SN1 >> Nucleophilic substitution after glutathione-induced nitrenium ion formation OR SN1 >> Nucleophilic substitution after glutathione-induced nitrenium ion formation >> C-Nitroso Compounds OR SN2 OR SN2 >> Alkylation, direct acting epoxides and related OR SN2 >> Alkylation, direct acting epoxides and related >> Epoxides and Aziridines OR SN2 >> Alkylation, direct acting epoxides and related after P450-mediated metabolic activation OR SN2 >> Alkylation, direct acting epoxides and related after P450-mediated metabolic activation >> Polycyclic Aromatic Hydrocarbon Derivatives OR SN2 >> Direct acting epoxides formed after metabolic activation OR SN2 >> Direct acting epoxides formed after metabolic activation >> Quinoline Derivatives OR SN2 >> SN2 at an activated carbon atom OR SN2 >> SN2 at an activated carbon atom >> Quinoline Derivatives by DNA binding by OASIS v.1.3

Domain logical expression index: "g"

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

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as 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 >> Alkyl phenols 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 >> Hydroquinones OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Methylenedioxyphenyl 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 ketones OR Schiff base formers 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 >> Polycyclic (PAHs) and heterocyclic (HACs) aromatic hydrocarbons-SN1 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 >> Primary aromatic amine OR SN1 >> Nitrenium Ion formation >> Secondary aromatic amine OR SN1 >> Nitrenium Ion formation >> Tertiary aromatic amine OR SN2 OR SN2 >> Direct Acting Epoxides and related OR SN2 >> Direct Acting Epoxides and related >> Sulfuranes by DNA binding by OECD

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Non binder, without OH or NH2 group by Estrogen Receptor Binding

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Non binder, impaired OH or NH2 group OR Non binder, MW>500 OR Non binder, non cyclic structure by Estrogen Receptor Binding

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OASIS v1.3

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> Ester aminolysis OR Acylation >> Ester aminolysis >> Dithiocarbamates OR Michael Addition OR Michael Addition >> Michael addition on conjugated systems with electron withdrawing group OR Michael Addition >> Michael addition on conjugated systems with electron withdrawing group >> alpha,beta-Carbonyl compounds with polarized double bonds  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 >> Polarised Alkenes OR Michael Addition >> Polarised Alkenes >> Polarised Alkene - alkenyl pyridines, pyrazines, pyrimidines or triazines  OR Michael Addition >> Quinoide type compounds OR Michael Addition >> Quinoide type compounds >> Quinone methide(s)/imines; Quinoide oxime structure; Nitroquinones, Naphthoquinone(s)/imines  OR Nucleophilic addition OR Nucleophilic addition >> Addition to carbon-hetero double bonds OR Nucleophilic addition >> Addition to carbon-hetero double bonds >> Ketones by Protein binding by OASIS v1.3

Domain logical expression index: "m"

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

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Metal atoms were identified OR Metals (1a) OR Non-steroid nucleus derived estrogen receptor (ER) and androgen receptor (AR) OR Non-steroid nucleus derived estrogen receptor (ER) and androgen receptor (AR) >> 4-alkylphenol-like derivatives (2b-3) OR Not covered by current version of the decision tree OR Not known precedent reproductive and developmental toxic potential by DART scheme v.1.0

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as No alert found by in vitro mutagenicity (Ames test) alerts by ISS

Domain logical expression index: "p"

Referential boundary: The target chemical should be classified as Heterocyclic Polycyclic Aromatic Hydrocarbons OR Polycyclic Aromatic Hydrocarbons by in vitro mutagenicity (Ames test) alerts by ISS

Domain logical expression index: "q"

Referential boundary: The target chemical should be classified as No alert found by in vivo mutagenicity (Micronucleus) alerts by ISS

Domain logical expression index: "r"

Referential boundary: The target chemical should be classified as 1-phenoxy-benzene OR H-acceptor-path3-H-acceptor by in vivo mutagenicity (Micronucleus) alerts by ISS

Domain logical expression index: "s"

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

Domain logical expression index: "t"

Parametric boundary:The target chemical should have a value of log Kow which is >= 2.62

Domain logical expression index: "u"

Parametric boundary:The target chemical should have a value of log Kow which is <= 4.3

Conclusions:
4-methoxy-2-methyl-N-phenylaniline 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 3.3 with log kow as the primary descriptor and considering the five closest read across substances, gene mutation was predicted for 4-methoxy-2-methyl-N-phenylaniline. 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-methoxy-2-methyl-N-phenylaniline 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
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Gene mutation in vitro:

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

4-methoxy-2-methyl-N-phenylaniline. The studies are as summarized below:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, gene mutation was predicted for 4-methoxy-2-methyl-N-phenylaniline. 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-methoxy-2-methyl-N-phenylaniline 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 3.3 with log kow as the primary descriptor and considering the five closest read across substances, chromosomal aberration was predicted for 4-methoxy-2-methyl-N-phenylaniline. The study assumed the use of Chinese hamster ovary (CHO) cell line with and without S9 metabolic activation system. 4-methoxy-2-methyl-N-phenylaniline 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-methoxy-2-methyl-N-phenylaniline using the battery approach from Danish QSAR database (2017). 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-methoxy-2-methyl-N-phenylaniline 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.

An in vitro mammalian cell gene mutation study was designed and conducted (Sustainability Support Services (Europe) AB, 2015) to determine the genotoxicity profile of 70 -80% structurally similar read across chemical Methyl 2-napthyl ether (CAS No. 93-04-9) when administered to Chinese Hamster Ovary (CHO) cells. In the genotoxicity test, methyl 2-napthyl ether was administered to CHO cells for 3 hrs at the dose levels of 0, 0.1, 0.25, 0.5 or 1.0 mM and in the absence or presence of exogenous metabolic activation. CHO cells representing the negative controls were exposed to the vehicle. Positive controls, such asN-ethyl-N-nitrosourea (ENU) experiments without metabolic activation and 7,12-dimethylbenz(a) anthracene in experiments with metabolic activation, were also included in each test. The positive control ENU gave a clear indication of gene mutations occurring while no other treatment gave rise to gene toxicity. One very diffuse colony was seen in one well out of four at the concentration of 0.5 mM and in the absence with 4% S9 liver microsomal fraction, and two very diffuse colonies were detected in one well out of four at the concentration of 0.1 mM and in the presence with 4% S9 liver microsomal fraction. These diffuse colonies are not regarded to be relevant since the three spots were only mildly colored by crystal violet, thus indicating that it were small clusters of apoptotic cells taking their last breath instead of cells surviving the TG-selection. This is further supported by the results of the higher tested concentrations of methyl 2-napthyl ether, i.e. these concentrations did not show any evidence of diffuse or clear colonies present. When the mutation frequency was determined, a frequency of 5.35 x 10-4was shown after a 3 hour exposure of ENU as the positive control and in the absence of S9 liver microsomal fraction. Since no other tested concentration of methyl 2-napthyl ether in the absence or presence of S9 liver microsomal fraction resulted in colonies, we conclude that methyl 2-napthyl ether does not give rise to gene mutations when CHO cells are exposedin vitroto the test chemical at 0, 0.1, 0.25, 0.5 or 1.0 mM for 3 hrs. Based on the results of the current study, we conclude that methyl 2-napthyl ether does not give rise to gene mutations when CHO cells are exposed to the test chemicalin vitroat 0, 0.1, 0.25, 0.5 or 1.0 mM for 3 hrs, in the presence or absence of metabolic activation.

Gene mutation toxicity study was performed by Florin et al (Toxicology, 1982) to determine the mutagenic nature of the 50 -60% structurally similar read across chemical 2-Ethoxynaphthalene (RA CAS no 93 -18 -5; IUPAC name: 2-Ethoxynaphthalene). The test was performed as per the Spot test protocol. 2-Ethoxynaphthalene was dissolved in ethanol and applied at a concentration of 0 or 3 µmole/plate. In absence of a background lawn of bacteria on the plates (indicating toxicity) the test was repeated with a lower concentration of the substance. 2-Ethoxynaphthalene did not induce reversion of mutant strains in S. typhimurium LT-2 strain TA 98, TA 100, TA 1535 and TA 1537 in the presence and absence of S9 metabolic activation system and hence is not likely to classify as gene mutant in vitro.

In another study by Haworth et al (Environmental Mutagenesis, 1983), Gene mutation toxicity study was performed to determine the mutagenic nature of the 50 -60% structurally similar read across chemical Diphenyl oxide (RA CAS no 101 -84 -8; IUPAC name: 1,1'-Oxybis-benzene). The study was performed by the preincubation protocol using Salmonella typhimurium strains TA1535, TA1537, TA98, and TA100 both in the presence and absence of S9 metabolic activation system. Preincubation was carried at 37°C for 20 mins followed by exposure period of 48 hrs at dose levels of 0, 3.3, 10.0, 33.3, 100.0 or 333.3 µg/plate. DMSO was used as solvent control and concurrent positive control chemicals were included in the study. A dose related increase in the number of revertants was noted whether it be twofold over background or not. Diphenyl oxide did not induce mutation in the Salmonella typhimurium strains TA1535, TA1537, TA98, and TA100 both in the presence and absence of S9 metabolic activation system and hence 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-methoxy-2-methyl-N-phenylaniline does not exhibit gene mutation in vitro. Hence the test chemical is not likely to classify as a gene mutant in vitro.

Justification for classification or non-classification

Based on the data available for the target chemical and its read across, 4-methoxy-2-methyl-N-phenylaniline (CAS no 41317 -15 -1) does not exhibit gene mutation in vitro. Hence the test chemical is not likely to classify as a gene mutant in vitro.

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