Registration Dossier

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Dec 10, 1993 - Feb 08, 1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

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

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
May 26, 1983
Deviations:
no
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
S9 liver microsomal fraction of male Wistar rats
Test concentrations with justification for top dose:
According to the results of this pre-experiment the concentrations applied in the main experiments were chosen. The concentration range covered two logarithmic decades.
The maximum concentration was 5000.0 µg/plate. In this study six adequately spaced concentrations were tested. Two independent experiments were performed.
According to the dose selection criteria the test article was tested at the following concentrations:
33.3, 100.0, 333.3, 1000.0, 2500.0, and 5000.0 µg/plate
Vehicle / solvent:
aqua bidest.
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
sodium azide
other: 4-nitro-o-phenylene-diamine, 2-aminoanthracene
Evaluation criteria:
A test article is considered positive if either a dose related and reproducible increase in the number of revertants or a significant and reproducible increase for at least one test concentration is induced.
A test article producing neither a dose related and reproducible increase in the number of revertants nor a significant and reproducible positive response at anyone of the test points is considered non-mutagenic in this system.
A significant response is described as follows: A test article is considered mutagenic if in strain TA 100 the number of reversions is at least twice as high and in strains TA 1535, TA 1537 and TA 98 at least three times higher as compared to the spontaneous reversion rate.
Also, a dose-dependent and reproducible increase in the number of revertants is regarded as an indication of possibly existing mutagenic potential of the test article regardless whether the highest dose induced the above described enhancement factors or not.

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
other: TA 1535, TA 1537, TA 98, TA 100
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: yes / >= 1000 µg/plate and higher (with and without metabolic activation)
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
other: TA1535, TA 1537, TA 98, TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: yes / >= 1000 µg/plate and higher (with and without metabolic activation)
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
No substantial increases in revertant colony numbers of any of the four tester strains were observed following treatment with MTPP-Cl at any concentration level, either in the presence or absence of metabolic activation (S9 mix) in experiment I. Due to these results the second experiment was carried out as a preincubation test. In this experiment, there was also no tendency of higher mutation rates with increasing concentrations in the
range below the generally acknowledged border of biological relevance.
Appropriate reference mutagens were used as positive controls. They showed a distinct increase in induced revertant colonies.
Remarks on result:
other: plate incorporation test

Applicant's summary and conclusion

Conclusions:
It can be stated that during the described mutagenicity test and under the experimental conditions reported, the test article did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used. Therefore, MTPP-CI is considered to be non-mutagenic in this Salmonella typhimurium reverse mutation assay.