1-bromobutane

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:

02 May 2002 and 31ay 2002

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

1-bromobutane

EC Number:

203-691-9

EC Name:

1-bromobutane

Cas Number:

109-65-9

Molecular formula:

C4H9Br

IUPAC Name:

1-bromobutane

Details on test material:

Purity 99.7%

Method

Target gene:

Histidine

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Details on mammalian cell type (if applicable):

N/A

Additional strain / cell type characteristics:

other: See any other information on materials and methods section

Metabolic activation:

with and without

Metabolic activation system:

S9 fraction from the livers of Aroclor 1254-induced Sprague Dawley rats

Test concentrations with justification for top dose:

Six concentrations: 15, 50, 150, 500, 1500 and 5000 µg/plate

Vehicle / solvent:

Dimethyl sulphoxide

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: See any other information on materials and methods.

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (top application)
Preincubation period: 37oc for ~10hrs.
Analysis for concentration, homogeneity and stability of the test material- not determined.
Vehicle controls were used as negative control.
Vehicle and positive controls were used in parallel with the test material with and without S9 (microsomal enzyme fraction)

NUMBER OF REPLICATIONS: 3

DETERMINATION OF THE TEST MATERIAL TOTOXICITY :
5 doses: 50, 150, 1500 and 5000 µg/plate and a vehicle control were tested.

NUMBER OF REPLICATIONS: 2
Incubation period: 37oc for ~48hr.
- Method: bacterial lawn
Frequency of revertant colonies assessed by Domino colony counter.

Evaluation criteria:

Evaluation of Toxicity:
The compound induced toxicity was evaluated on every plate at the end of the incubation period by studying the aspect of the bacterial lawn and was examined by the mean number of revertant colonies for the toxicity assay.

A compound is considered genotoxic if:
• the number of His+ revertant colonies/plate at one concetration is at least twice the number of spontaneous revertants.
• the increase in the number of revertants is concentration related .

Statistics:

Methods recommended by the UKEMS (5) and normally Dunnett's method of linear regression were used to evaluation of the results.

Results and discussion

Test results

Key result

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:

seen at 5000 µg/plate.

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING/SCREENING STUDIES:
In the preliminary study, the test material exhibited toxicity at 5000 ug/plate to the strains of bacteria (TA100 and EP2uvrA) and this was therefore
maintained as the highest concentration for the definitive study.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
Toxic effect (sparsity of the background lawn with or without a decrease in the number of reverant colonies/plate) was noted at 5000 µg/plate.

ADDITIONAL INFORMATION ON GENOTOXICITY:
No genetic toxicity was induced at any concentration with any of the tester strains. Genotoxocity was shown with the positive control substances
showing the validity of the test system. A second study was conducted with the same concentrations and same tester strains as the first and
produced results in agreement with the original definitive study.

Remarks on result:

other: strain/cell type:

Remarks:

Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

The genotoxic potential of butyl bromide was assessed by the Ames test on four Salmonella typhimurium tester strains: TA1537, TA1535, TA98 and TA100 and 1 Escherichia coli strain WP2uvrA, both in the absence and presence of metabolic activation.
butyl bromide was tested at concentrations ranging from 15 to 5,000 µg/plate.
In all studies, whether in the presence or in the absence of metabolic activation, no increase was observed in the number of His+ revertant colonies/plate at any of the concentrations tested, on the five tester strains, with and without S9 mix.
In conclusion, butyl bromide was not genotoxic in the Ames test, with or without metabolic activation.

Executive summary:

The genotoxic potential of butyl bromide was assessed by the Ames test on five Salmonella typhimurium tester strains: TA1535, TA1537, TA98 and TA100 and E.coli strain WP2uvrA, both in the absence and presence of metabolic activation.

Butyl bromide was tested at concentrations ranging from 15 to 5,000 µg/plate.

No significant increase in the frequency of revertant colonies of bacteria were recorded for any of the strains of Salmonella and E.coli used, at any dose level with or without metabolic activation.