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Diss Factsheets

Administrative data

in vitro gene mutation study in bacteria
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 1 December 1993 to 17 February 1994
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference Type:
study report

Materials and methods

Test guideline
according to guideline
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
not specified
Principles of method if other than guideline:
The assay is based on the use of Salmonella typhimurium tester strains that revert from histidine dependence (auxotrophy) to histidine independence (prototrophy) in the presence of a genotoxic agent, with or without a metabolic activation system.
GLP compliance:
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Reference substance name:
n-hexyl bromide
n-hexyl bromide
Constituent 2
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Test material form:
solid - liquid: suspension
migrated information: dispersion
Details on test material:
The study was performed on n6Hexyl bromide;
Assay: > 98.5 %
Storage: in dark and at room temperature
Expiry date: April 1994


Target gene:
Species / strain
Species / strain / cell type:
other: S. typhimurium TA 1535, TA 1537, TA1538, TA 98 and TA 100
Additional strain / cell type characteristics:
DNA polymerase A deficient
Metabolic activation:
with and without
Metabolic activation system:
S-9 mix from Aroclor 1254-induced rat liver (5 %)
Test concentrations with justification for top dose:
Toxicity study
TA1535, TA100 (-S-9 mix) 100 - 500 - 1000 - 5000 - 10000 µg/plate

Genotoxicity study
First study 5 - 10 - 50 - 100 - 250 - 500 µg/plate
Second study 10 - 50 - 100 - 250 - 375 µg/plate
Vehicle / solvent:
DMSO at 100 µl/plate
Untreated negative controls:
Negative solvent / vehicle controls:
True negative controls:
Positive controls:
Positive control substance:
sodium azide
other: 2-aminoanthracene
Details on test system and experimental conditions:
The 2 genotoxicity tests were performed on the 5 Salmonella typhimurium tester strains with and with out S-9 mix.
Assays were performed in triplicate for each concentration of n-Hexyl bromide.
Assays were performed by combining in each tube:
- 0.5 ml of either phosphate buffer 0.2 M (pH = 7.4), or S-9 mix,
- 0.1 ml of n-Hexyl bromide;
- 2 ml of top agar supplemented with histidine and biotin,
- 0.1 ml of tester strain.
Just after the tester was added, the mixture was rapidly homogenized and then poured onto minimal agar plates.
As a result of n-Hexyl bromide slight volatility, plates were incubated in closed stainless steel vessels, using one vessel per concentrations.
After 48-hour incubation at 37°C, His+ revertant colonies were counted and the bacterial lawn appearance was examined macroscopically and microscopically (lens 10 x 10).
Evaluation criteria:
The revertant colonies were counted using an AMS 40-10 counter or with the naked eye when there was less than 20 of them.
The results are expressed as the number of His+ revertant colonies/plate. The following parameters were calculated for each concentration:
- the number of net revertants (mean numbers of His+ revertant colonies/plate less the mean number of spontaneous revertant colonies/plate for each concentration) ;
- the induction factor (ratio of the mean number of net revertant colonies/plate to the mean number of spontaneous revertant colonies/plate for each concentration).

Results and discussion

Test results
Species / strain:
other: TA 1535, TA 1537, TA1538, TA 98 and TA 100
Metabolic activation:
with and without
Cytotoxicity / choice of top concentrations:
At 1000 µg/plate upwards
Vehicle controls validity:
Untreated negative controls validity:
not examined
Positive controls validity:
Remarks on result:
other: all strains/cell types tested
Migrated from field 'Test system'.

Any other information on results incl. tables

For the two studies, with and without metabolic activiation, n-hexyl bromide did not induce any increase in the number of His+ revertant colonies/plate on the 5 tester strains, regardless of the concentration.

Besides, the positive controls, tested in the presence of S-9 mix when required, induced a marked increase in the number of His+ revertant colonies/plate, thus confirming the sensitivity of the cultures ans the activity of S-9 mix.

Applicant's summary and conclusion

Interpretation of results (migrated information):

n-Hexyl bromide was not genotoxic in the Ames test
Executive summary:

The genotoxic potential of n-Hexyl bromide was assessed by the Ames test on five Salmonelle typhimurium tester strains: TA1535, TA1537, TA1538, TA98 and TA100, both in the absence and presence of metabolic activation.

n-Hexyl bromide was dissolved and diluted in dimethyl sulfoxide and tested at concentrations ranging from 10 to 10000 µg/plate.

During the preliminary toxicity study performed on TA100 and TA1535 without s-9 mix at concentrations of 100, 500, 1000, 5000 and 10000 µg/plate, n-Hexyl bromide was toxic from 500 µg/plate upwards. Consequently, this concentration was selected to be the top concentration for the first genotoxicity study.

During the first genotoxicity study performed at concentrations of 5, 10, 50, 100, 250 and 500 µg/plate, a slight toxic effect was noted mainly at 500 µg/plate. 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 concentration tested on the five tester strains.

During the second genotoxicity study performed at concentrations of 10, 50, 100, 250 and 375 µg/plate, a slight toxic effect was noted mainly at 375 µg/plate on TA1535, TA98 and TA100 with and without S9 mix, and on TA 1537 and TA 1538 without S-9 mix. As during the first study, no increase in the number of His+ revertant colonies/plate was noted whatever the concentration tested on the five tester strains, with and without metabolic activation.

In conclusion, n-Hexyl bromide was not genotoxic in the Ames test with and without metabolic activation.