2-(N-methyl-p-toluidino)ethanol

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 472 (Genetic Toxicology: Escherichia coli, Reverse Mutation Assay)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2-(N-methyl-p-toluidino)ethanol

EC Number:

220-638-5

EC Name:

2-(N-methyl-p-toluidino)ethanol

Cas Number:

2842-44-6

Molecular formula:

C10H15NO

IUPAC Name:

2-[methyl(4-methylphenyl)amino]ethan-1-ol

Test material form:

liquid: viscous

Method

Target gene:

Histidine Mutation additional Mutations
hisG46 hisC3076 hisD3052 LFS Repair R Factor
TA1535 TA1537 rfa uvrB -
TA100 TA98 rfa uvrB +R

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Rat liver S9 mix

Test concentrations with justification for top dose:

ten doses of test article ranging from 5,000 to 6.67 µp per plate, one plate per dose, both in the presence and absence of S9 mix. Doses tested in the mutagenicity assay were selected based on the results of the dose rangefinding study conducted on the test article using tester strains TA 100 and WP2uvrA in both the presence and absence of S9 mix with one plate per dose. Ten doses of test article (from 5000 to 6.67 µg per plate) were tested and the results are presented in Tables I and 2. These data were generated in Experiment 20880-A1. Cytotoxicity was observed with tester strain at 5,000 µg per plate in the presence of S 9 mix and at 3,330 µg per plate and above in the absence of S9 mix as evidenced by a reduction in the number of revertants per plate and a slight thinning of the bacterial background lawn. No cytotoxicity was observed with tester strain WP2uvrA in either the presence or absence of S9 mix as evidenced by a normal background lawn and no decrease in the number or revetants per plate.

Vehicle / solvent:

DMSO

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

2-nitrofluorene

sodium azide

benzo(a)pyrene

other: 2-aminoanthracene, ICR-191

Evaluation criteria:

The number of revertant colonies per plate for the vehicle, controls and all plates containing test article were counted manually. The number of revertant colonies per plate for the positive controls were counted by automated colony counter.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

Cytotoxicity was observed with tester strain at 5000 µg per plate in the presence of S9 mix and at 3330 µg per plate and above in the absence of S9 mix as evidenced by a reduction in the number of revertants per plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not valid

True negative controls validity:

not valid

Positive controls validity:

valid

Any other information on results incl. tables

Test Article Handling

The test article, FIRSTCURE MHPT, was stored at room temperature. The test article formed an unworkable (non-homogeneous) suspension in water at a concentration of 99.6 mg per ml. The test article formed a solution in dimethlsulfoxide (DMSO) at aconcentration of 99.8 mg per ml. For this reason, DMSO (CAS# 67-68-5) was used as the vehicle. At 100 mg per ml, which was the most conccentrated stock dilution prepared for the mutagenicity assay, the test article formed a transparent colorless solution. The test article remained a solution in all succeeding dilutions prepared for the mutagenicity assay

           B.        Dose Range finding Study

Doses tested in the mutagenicity assay were  based on the results of the dose rangefinding study conducted on the test article using and WP2uvrA in both the presence and absence of S9 mix with one plate per dose. Ten doses of test article (from 5000 to 6.67 µg per plate) were tested and the results are presented in Tables I and 2.These data were generated in Experiment 20880-AI .Cytotoxicity was observed with tester strain T100 at 5000 µg per plate in the presence of S9 mix and at 3330 µg per plate and above in the absence of S9 mix as evidenced by a reduction in the number of revertants per plate and a slight thinning of the bacterial background lawn. No cytotoxicity was observed with tester strain WP2uvrA in either the presence or absence of S9 mix as evidenced by a normal background lawn and no decrease in the number or revetants per plate.

            c.       Mutagenicity Assay

The mutagenicity assay results for FIRSTCURE MHPT are presented in Tables 3 and 4.These data were generated in Experiment 20880-BI.The data are presented as individual plate counts (Table 3) and as mean revertants per plate ± standard deviation (Table 4) for each treatrnent and control group.

The results of the dose range finding study were used to select the six doses tested in the assay. The doses tested with all tester strains were 5000, 3330, 1000, 333, 100, and 33,3 pg per plate in both the presence and absence of S9 mix.

In Experiment 20880-Bl (Tables 3 and 4), all data were acceptable and no positive increases in the mean number of revenants per plate were observed with any of the tester strains in either the presence of absence of S9 mix.

All criteria for a valid study were fulfild.

Applicant's summary and conclusion

Conclusions:

The results of the Salmonella Escherichia coli/Mammalian-Microsome Reverse Mutation Assay indicate that under the conditions of this study, ChemFirst, Inc.'s test article, MHPT, did not cause a positive increase in the mean number of revenants per plate with any of the tester strains either in the presence or absence of microsomal enzymes prepared from Aroclor- induced rat liver (S9)

Executive summary:

At the request of ChemFirst, Inc., Covance investigated MHPT for Mutagenic activity in the Salmonella - Escherichia coli Reverse Mutation Assay. This assay evaluated the test article and/or its metabolites for their abi!ity of induce reverse mutations at the histidine locus in the genome of specific Salmonella typhimurium tester strains and at the tryptophan locus in Echerichia coli tester strain both in the presence and absence of an exogenous metabolic activation system of mammalian microscpal enzymes derived from Aroclor^TM-induced rat liver (S9). The doses tested in the mutagenicity assay were selected based on the results of a dose rangefinding study using tester strains TA100 and WP2uvrA and ten doses of test article ranging from 5000 to 6.67 µp per plate, one plate per dose, both in the presence and absence of S9 mix. The tester strains used in the mutagenicity assay were Salmonella typhimurium tester strains TA98, TA 100, TA1 535, TA1537, and Escherichia coli tester strain WP2uvrA. The assay was conducted with six doses of test article in both the presence and absence of S9 mix along with concurrent vehicle and positive controls using three piates per dose. The doses tested with all tester strains were 5000, 3330, 1000, 333, 100 and 33.3 µg per plate in both the presence and absence of S9 mix. The results of the Salmonella - Escherichia coli/ Reverse Mutation Assay indicate that under the conditions of this study, ChemFirst, Inc.'s test article, MHPT, did rot cause a positive increase in the mean number of revertants per plate with any of the tester strains either in the presence or absence of microsomal enzymes prepared from Aroclor induced rat liver (S9).