Reaction mass of m,alpha-dimethylstyrene and p,alpha-dimethylstyrene

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: New Guidebook for Mutagenicity Tests using Microorganisms, compiled by Chemical Substance Research Division, Safety and Health Department, Ministry of Labor

Version / remarks:

1990

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of m,alpha-dimethylstyrene and p,alpha-dimethylstyrene

EC Number:

909-129-5

Molecular formula:

C10H12

IUPAC Name:

Reaction mass of m,alpha-dimethylstyrene and p,alpha-dimethylstyrene

Test material form:

liquid

Details on test material:

Indentification
Cas: 26444-18-8
Purity: 97.35%
batch: A94-015
Storage conditions: Not specified

Method

Target gene:

- S. typhimurium: Histidine gene
- E. coli: Tryptophan gene

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 induced by a combination of phenobarbital and benzoflavone

Test concentrations with justification for top dose:

Dose setting study (without and with S9) for all strains: 5, 10, 50, 100, 500, 1000, and 5000 µg/plate

Growth inhibition was observed for TA98, TA100, TA1535 and TA1537 at 50 µg/plate and for WP2uvrA at 100µg/plate.

Main study: (without and with S9) TA100, WP2uvrA TA1535, TA1537 and TA98: 0.781, 1.56, 3.13, 6.25, 12.5, 25, 50, 100 µg/plate.

Vehicle / solvent:

- solvent used: DMF
- Justification for choice of solvent: DMF is an appropiate solvent for this assay.

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

other: 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide

Remarks:

without S9, 0.01 µg/plate in DMSO for TA100

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

without S9, 0.5 µg/plate in DMSO for TA1535

Controls 3

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

other: ICR-191

Remarks:

without S9, 1 µg/plate in DMSO for TA1537

Controls 4

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

other: 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide

Remarks:

without S9, 0.01 µg/plate in DMSO for WP2uvrA

Controls 5

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

other: 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide

Remarks:

without S9, 0.1 µg/plate in saline for TA98

Controls 6

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

with S9. in DMSO for tester strains, TA98 0.5µg/plate, TA1535 2 µg/plate, TA1537 2 µg/plate, WP2uvrA 10 µg/plate

Controls 7

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

no

Positive control substance:

benzo(a)pyrene

Remarks:

With S9, 5 µg/plate in DMSO for TA100

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar

DURATION
- Exposure duration: 48 hour

NUMBER OF REPLICATIONS:
- One dose setting and one main experiment, both in duplicate

NUMBER OF CELLS EVALUATED: 10E8 per plate

DETERMINATION OF CYTOTOXICITY
- Method: Observing if growth inhibition has occurred by counting a decrease in revertants

OTHER EXAMINATIONS:
- not performed

Evaluation criteria:

A test substance is considered positive if:
The result of the mutagenicity test on the test substance was concluded to be positive if the number of the colonies of a revertant that had appeared was not less than two times as many as that of the colonies of a revertant appearing in the case of the solvent controls and there was a dose-response relationship observed.

Further, if it was confirmed that there had been no entry of any unwanted bacteria in the sterility test, the number of the colonies of a revertant of the solvent control substances and the positive control substances was within the range of the historical background data and there were no less than four concentration groups that show growth inhibition of bacteria, then the test was judged to be valid.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS

Cytotoxicty was observed in the dose setting test.
TA1535,TA1537, TA98, TA100, without and with S9: 50 µg/plate and above.
WP2uvrA, without and with S9: 100 µg/plate and above.

Applicant's summary and conclusion

Conclusions:

In an AMES test, similar to OECD 471 Isopropenyl toluene (mixture of m- and p-isomer) was found not to be mutagenic with or without metabolic activation.

Executive summary:

An AMES test was performed similair to OECD 471. Cytoxicity was observed for the strains TA1535,TA1537, TA98, TA100 at 50 µg/plate and above with and without S9 and for WP2uvrA at 100 µg/plate and above with and without S9. No significant dose-related increase in the number of revertants with or without metabolic activation was seen beneath the concentrations that induced growth inhibition. Based on the results of this study it is concluded that Isopropenyl toluene (mixture of m- and p-isomer) is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay with or without metabolic activation.