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:
key study
Study period:
2000
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Qualifier:
according to
Guideline:
EPA OPPTS 870.5265 (The Salmonella typhimurium Bacterial Reverse Mutation Test)
Qualifier:
according to
Guideline:
other: EU Method B.14
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid
Details on test material:
- Name of test material (as cited in study report): 2,6-DMPA
- Physical state: liquid
- Analytical purity: 98.8 %
- Purity test date: May 20, 1999
- Lot/batch No.: 34
- Storage condition of test material: room temperature

Method

Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 98
Species / strain / cell type:
S. typhimurium TA 100
Metabolic activation:
with and without
Metabolic activation system:
S9 mix
Test concentrations with justification for top dose:
31.6, 100.0, 316.2, 1000.0, 2500.0 and 5000.0 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: DMSO was compatible with the survival of the bacteria and the S9 activation.
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
other: 4-nitro-o-phenylene-diamine ; 2-aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation); preincubation

DURATION
- Preincubation period: 60 min
- Exposure duration: 48 h

NUMBER OF REPLICATIONS: 3 per concentration
Evaluation criteria:
A test item is considered as mutagenic if : - a dose-related increase in the number of revertant occurs and/or
- a reproducible biologically relevant positive response for at least one of the test points occurs
in at least one strain with or without metabolic activation.
A biologically relevant increase is described as follows : - if in strain TA 100 the numbers of reversions is at least twice as high
- if in strain TA 98 the number of reversions is at least three times higher
as compared to the spontaneous rate.
Statistics:
The Mutation Factor is calculated by dividing the mean value of the revertant counts through the mean values of the solvent control.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

In conclusion it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test item did not
cause gene mutations by base pair changes or frameshifts in the genome of the tester strains used.
Therefore, 2,6-DMPA is considered to be non-mutagenic in this bacterial reverse mutation assay
Executive summary:

In order to investigate the potential of 2,6 -Dimethylphenoxyaceton for its ability to induce gene mutations the plate incorporation test

( experiment I ) and the pre-incubation test ( experiment II ) were performed with the Salmonella typhimurium strains TA 98 and

TA 100 .

The test item was tested in two independent experiments at several concentrations. Each assay was conducted with and without metabolic activation ( S9 mix). The concentrations, including the controls, were tested in triplicate.The following concentrations of the test item were prepared and used in the experiments : 31.6, 100.0, 316.2, 1000.0, 2500 and 5000 µg/plate

Toxic effects of the test item were observed in both experiments at the upper concentrations both strains used with and without metabolic activation.

No substantial increase in revertant colony numbers of any of the two tester strains were detected at any concentration level of the test item either with or without metabolic activation in both independently performed experiments.

As positive controls reference mutagens were tested in parallel to the test item. They showed a distinct increase of induced revertant colonies.

The reported data of this mutagenicity test show that the test item did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used.

Therefore, 2,6 -DMPA is considered to be non-mutagenic in this bacterial reverse mutation assay.