1-bromohexane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In the available study, no genotoxic effect whatever the concentration on any of the five tester strains with and without S-9 mix. Positive controls induced a marked increase in the revertant colonies/plate for all strains.

Link to relevant study records

Reference

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:

From 1 December 1993 to 17 February 1994

Reliability:

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.

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

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:

no

Type of assay:

bacterial reverse mutation assay

Target gene:

Histidine

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:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

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).

Species / strain:

other: TA 1535, TA 1537, TA1538, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

At 1000 µg/plate upwards

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

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.

Conclusions:

Interpretation of results (migrated information):
negative

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.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Justification for classification or non-classification

In the absence of any positive in vitro genetic toxicity data, n-hexyl bromide does not require classification as mutagenic in accordance with Directive 67/548/EEC and the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.