2-methylbutene

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study, no restrictions, fully adequate for assessment

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1981

Report date:

1981

Reference 2

Reference Type:

publication

Title:

Genetic toxicology testing of 41 industrial chemicals

Author:

Dean BJ, Brooks TM, Hodson-Walker G and Hutson DH

Year:

1985

Bibliographic source:

Mutation Research 153:57- 77

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2-methyl-2-butene

IUPAC Name:

2-methyl-2-butene

Constituent 2

Reference substance name:

2-methylbut-2-ene

EC Number:

208-156-3

EC Name:

2-methylbut-2-ene

Cas Number:

513-35-9

IUPAC Name:

2-methylbut-2-ene

Details on test material:

- Name of test material (as cited in study report): 2-methyl-2-butene
- Supplier: Shell Chemie, Rotterdam, The Netherlands
- Batch number: Indent 9200/9579
- Purity: 84.9%
- Composition of test material, percentage of components: 2-methylbut-2-ene 84.9%, 3-methylbut-1-ene 7.3%, isopentane 3.6%, n-pentane 1.0%, trans pent-2-ene 1.2%, cis pent-1-ene 0.3%, pent-1-ene 0.2%, 3-methylpentane + trans 1,3-pentadiene 0.3%, tert. amyl alcohol 0.4%, total C4 compounds 0.2%, polymers 0.1%
- Expiration date of the lot/batch: 1 January 1981
-Storage conditions: in the dark at 0-5°C

Method

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:

S. typhimurium, other: TA1538

Species / strain 3

Species / strain / cell type:

E. coli WP2

Species / strain 4

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S-9

Test concentrations with justification for top dose:

31.25, 62.5, 125, 250, 500, 1000, 2000 and 4000 µg/plate

Vehicle / solvent:

- ethanol
Stability of dosing solutions: solutions of 2-methyl-2-butene in absolute ethanol were considered to be stable for at least 1 day.

Controls

Negative solvent / vehicle controls:

yes

Remarks:

ethanol

Positive controls:

yes

Positive control substance:

other: benzo(a)pyrene, 4-nitroquinoline-N-oxide, sodium azide, neutral red

Remarks:

benzo(a)pyrene (TA1538,TA98, TA100); neutral red (TA1537), 4-nitroquinoline-N-oxide (E.coli strains) and sodium azide (TA1535)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation) with pre-incubation

DURATION
- Preincubation period: 30 minutes
- Exposure duration: 48 hours

NUMBER OF REPLICATIONS:
- Three plates per dose level using sealed containers
-Two replicate assays were performed on different days

DETERMINATION OF CYTOTOXICITY
- Relative total growth

Evaluation criteria:

Data are interpreted on the basis of a consistent doubling of the spontaneous reversion frequency confirmed by a dose-response relationship. Where the number of induced revertants is less than twice the spontaneous rate, but a reproducible dose-related increase in revertants is detected, this is interpreted as a positive response.

Results and discussion

Test results

Test results 1

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:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium, other: TA538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 3

Species / strain:

E. coli WP2

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 4

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative with metabolic activation
negative without metabolic activation

2-methyl-2-butene was not mutagenic in any of the five strains of Salmonella or in the two strains of E. coli tested in the presence or absence of metabolic activation.

Executive summary:

2 -methyl-2 -butene was tested in an Ames assay in 5 strains of Salmonella typhimurium (TA1535, TA 1537, TA1538, TA 100, and TA98) and in 2 strains of Escherichia coli (WP2 and WP2uvrA) in the presence and absence of rat liver S-9. Five dose levels were tested, with three plates per dose level using sealed containers. Concurrent positive and solvent controls were also tested with and without metabolic activation (rat liver S9). Two replicate assays were performed on different days to confirm the reproducibility of the results.

2 -methyl-2 -butene was not mutagenic in any of the five strains of Salmonella or in the two strains of E. coli tested in the presence or absence of metabolic activation.