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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
Study period:
27th October - 10th December 1993
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.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1993
Report Date:
1994

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
> 99%

Method

Target gene:
Histidine
Species / strain
Species / strain / cell type:
other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100
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:
100, 500, 1000, 5000 and 10000 µg/plate
Vehicle / solvent:
DMSO (1%)
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 (plate incorporation)

DURATION
- Preincubation period: 8 - 9 hours
- Exposure duration: 48 hours
- Expression time (cells in growth medium): N/A
- Selection time (if incubation with a selection agent): N/A
- Fixation time (start of exposure up to fixation or harvest of cells): N/A

SELECTION AGENT (mutation assays): NDA
SPINDLE INHIBITOR (cytogenetic assays): NDA
STAIN (for cytogenetic assays): NDA

NUMBER OF REPLICATIONS: 3

DETERMINATION OF CYTOTOXICITY
- Method: bacterial lawn

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 the number of His+ revertant colonies/plate
The bacterial background lawn is examined folowing the criteria listed below:
- Normal background lawn
+ Partial sparsity of background lawn (microscopic observation, lens 10 x 10)
++ Sparsity of background lawn (macroscopic observation)
+++ Inhibition of background lawn or presence of background lawn colonies

Evaluation of Genotoxicity:
The revertant colonies were counted using an AMS 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 number of His+ revertants colonies/plate less the mean number of spontaneous revertants 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).

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 for TA98 and TA100 strains and three times this number for TA1535, TA 1537 and TA1538 strains
• the increase in the number of revertants is concentration related.
Statistics:
NDA

Results and discussion

Test results
Species / strain:
other: S. typhimurium TA 1535, TA 1537, TA3538, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
seen at 5000 µg/plate and above.
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 using TA1535 annd TA100 without activation, cytotoxocity was seen at 10,000 ug/plate and this was therefore maintained as the highest concentration for the definitive study.


ADDITIONAL INFORMATION ON CYTOTOXICITY:

A slight toxic effect (sparsity of the background lawn with or without a decrease in the number of reverant colonies/plate) was noted at 5000 and 10,000 µg/plate for plates with metabolic activation and at 10,000 µg/plate without metabolic activation.

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 n-propyl bromide was assessed by the Ames test on five Salmonella typhimurium tester strains: TA1353, TA1537, TA1538, TA98 and TA100, both in the absence and presence of metabolic activation.

n-propyl bromide was dissolved and diluted in dimethyl sulfoxide and tested at concentrations ranging from 100 to 10,000 µg/plate.

During the first genotoxicity study (HIS1005) performed at 100, 500, 1000, 5000 and 10,000 µg/plate, a slight toxic affect was observed mainly at 10,000 µg/plate on the five tester strains with S9 mux and in TA1535, TA 1538, TA98 and TA100 without S9 mix.

A second study (HIS1005A) performed at the same concentrations confirmed these results.

In both 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, n-propyl bromide was not genotoxic in the Ames test, with or without metabolic activation.
Executive summary:

The genotoxic potential of n-propyl bromide was assessed by the Ames test on five Salmonella typhimurium tester strains: TA1353, TA1537, TA1538, TA98 and TA100, both in the absence and presence of metabolic activation.

n-propyl bromide was dissolved and diluted in dimethyl sulfoxide and tested at concentrations ranging from 100 to 10,000 µg/plate.

During the first genotoxicity study (HIS1005) performed at 100, 500, 1000, 5000 and 10,000 µg/plate, a slight toxic effect was observed mainly at 10,000 µg/plate on the five tester strains with S9 mux and in TA1535, TA 1538, TA98 and TA100 without S9 mix.

A second study (HIS1005A) performed at the same concentrations confirmed these results.

In both 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, n-propyl bromide was not genotoxic in the Ames test, with or without metabolic activation.