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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other: GLP compliant guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report date:
1998

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Qualifier:
according to guideline
Guideline:
OECD Guideline 472 (Genetic Toxicology: Escherichia coli, Reverse Mutation Assay)
Qualifier:
according to guideline
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Isobutyryl chloride
EC Number:
201-194-1
EC Name:
Isobutyryl chloride
Cas Number:
79-30-1
Molecular formula:
C4H7ClO
IUPAC Name:
isobutyryl chloride
Details on test material:
- Name of test material (as cited in study report): Isobuttersäurechlorid
- Analytical purity: 99.5 %
- Batch number: Vers. 99/V
- Test substance number: 96/505
- Physical state: colorless liquid
- Storage condition of test material: room temperature

Method

Target gene:
his
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254-induced rat liver S-9 mix
Test concentrations with justification for top dose:
0, 20, 100, 500, 2500, 5000 µg/plate (standard plate test; first test)
0, 20, 100, 500, 1000, 1500 µg/plate (standard plate test; second test)
0, 0.8, 4, 20, 100, 500 µg/plate (preincubation test)
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: Due to the limited solubility of the test substance in water, DMSO was selected as the vehicle, which had been demonstrated to be suitable in bacterial reverse mutation tests and for which historical control data are available.
Controlsopen allclose all
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene
Remarks:
with S-9 mix for strains TA 1535, TA 100, TA 1537, TA 98 and E.coli WP2 uvrA
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: N-methyl-N'-nitro-N-nitrosoguanidine
Remarks:
without S-9 mix for strains TA 1535 and TA 100
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenyldiamine
Remarks:
without S-9 mix for strain TA 98
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
without S-9 mix for strain TA 1537
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
N-ethyl-N-nitro-N-nitrosoguanidine
Remarks:
without S-9 mix for strain E.coli WP2 uvrA
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation); preincubation

DURATION
Plate incorporation method:
- Exposure duration: ca. 48-72 hours at 37°C
Preincubation method:
- Preincubation period: 20 minutes at 37°C
- Exposure duration: ca. 48-72 hours at 37°C

NUMBER OF REPLICATIONS:
- 3 test plates per dose or per control

DETERMINATION OF CYTOTOXICITY
- Decrease in the number of revertants
- Reduced his- or trp- background growth
- Reduction in the titer
Evaluation criteria:
The test chemical is considered positive in this assay if a dose-related and reproducible increase in the number of revertant colonies (i.e. about doubling of the spontaneous mutation rate) in at least one tester strain is observed either without S-9 mix or after adding a metabolizing system.
A test substance is generally considered nonmutagenic in this test if the number of revertants for all tester strains were within the historical negative control range under all experimental conditions in two experiments carried out independently of each other.

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at concentrations of ≥1000 µg/plate in the standard plate test and ≥100 µg/plate in the preincubation assay
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
ADDITIONAL INFORMATION ON CYTOTOXICITY:
A bacteriotoxic effect (reduced his- or trp- background growth, decrease in the number of his+ or trp+ revertants, reduction in the titer) was observed at doses ≥ 1000 µg/plate onward (standard plate test) or ≥ 100 µg/plate (preincubation assay).

SOLUBILITY:
No precipitation of the test substance was found.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion