Registration Dossier

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
19 Sep 1996 - 28 Oct 1996
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
Title:
Unnamed
Year:
1997
Report date:
1997

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
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

Constituent 1
Chemical structure
Reference substance name:
4-bromoanisole
EC Number:
203-252-1
EC Name:
4-bromoanisole
Cas Number:
104-92-7
Molecular formula:
C7H7BrO
IUPAC Name:
4-bromoanisole
Details on test material:
Purity 98.75 %

Method

Target gene:
Histidine
Species / strain
Species / strain / cell type:
S. typhimurium, other: TA1535, TA100, TA1537, TA1538 and TA98
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:
Ethanol
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 ~10hr.
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
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 1500 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, the test material exhibited toxicity at and above 1500 ug/plate to the strain of Salmonella used (TA100) 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 1500 µg/plate and
above.

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 p-Bromoanisole was assessed by the Ames test on five Salmonella typhimurium tester strains: TA1535, TA1537, TA1538, TA98 and TA100, both in the absence and presence of metabolic activation.
p-Bromoanisole 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, p-Bromoanisole was not genotoxic in the Ames test, with or without metabolic activation.
Executive summary:

The genotoxic potential of p-Bromoanisole was assessed by the Ames test on five Salmonella typhimuriumtester strains: TA1535, TA1537, TA1538, TA98 and TA100, both in the absence and presence of metabolic activation.

p-Bromoanisole 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 used, at any dose level with or without metabolic activation.