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Toxicological information

Genetic toxicity: in vitro

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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

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1981
Report Date:
1981
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:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
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 / strainopen allclose all
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
Aroclor induced rat liver S-9
Species / strain:
other: TA1538
Metabolic activation:
with and without
Metabolic activation system:
Aroclor induced rat liver S-9
Species / strain:
E. coli WP2
Metabolic activation:
with and without
Metabolic activation system:
Aroclor induced rat liver S-9
Species / strain:
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:
- 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
Solvent 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 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 resultsopen allclose all
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no, but tested up to limit concentrations
Vehicle controls valid:
yes
Positive controls valid:
yes
Species / strain:
other: TA538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no, but tested up to limit concentrations
Vehicle controls valid:
yes
Positive controls valid:
yes
Species / strain:
E. coli WP2
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no, but tested up to limit concentrations
Vehicle controls valid:
yes
Positive controls valid:
yes
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no, but tested up to limit concentrations
Vehicle controls valid:
yes
Positive controls valid:
yes

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.