Registration Dossier

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study under GLP conditions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report Date:
2008

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes (incl. certificate)
Remarks:
2007-10-15
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Specific details on test material used for the study:
Name: 2,2'-Dihydroxy-4-methoxybenzophenone (CAS 131-53-3)
Description: Yellow solid
Batch number: 8010111
Storage conditions: Room temperature in the dark

Method

Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
S9-mix
Test concentrations with justification for top dose:
Based on a preliminary toxicity test using TA100 and E.coli, the following dose levels were used:
Salmonella strains, with and without S9: 5, 15, 50, 150, 500 and 1500 µg/plate
E. coli WP2vurA-, with and without S9: 15, 50, 150, 500, 1500 and 5000 µg/plate
Vehicle / solvent:
- Vehicle/solvent used: DMSO
- Justification for choice of solvent/vehicle: The test material was insoluble in sterile water at 50 mg/ml but soluble in dimethyl sulphoxide at the same concentration in solubility checks performed in-house.
Controls
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
9-aminoacridine
N-ethyl-N-nitro-N-nitrosoguanidine
benzo(a)pyrene
other: 2-Aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar; Direct plate incorporation method for the range-finding test and the main test

DURATION
- Exposure duration: 48h

NUMBER OF REPLICATIONS:
3 replicates per bacterial strain and concentration

The frequency of revertant coloniges was assessed using a Domino colony counter.
Rationale for test conditions:
Range-finding study
Evaluation criteria:
There are several criteria for determining a positive result, such as a dose-related increase in revertant frequency over the dose range tested and/or a reproducible increase at one or more concentrations in at least one bacterial strain with or without metabolic activation. Biological relevance of the results is considered first, statistical methods, as recommended by the UKEMS can also be used as an aid to evluation, however, statistical significance will not be the only determining factor for a positive response.
A test material will be considered non-mutagenic (negative) in the test system if the above criteria are not met.

Results and discussion

Test results
Species / strain:
other: All strains
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Results for the negative controls were considered as acceptable. All of the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies thus confirming the activity of the S9-mix and the sensitivity of the bacterial strains.

The test material was initially toxic from 500 and 1500 µg/plate to the strains of bacteria used, TA100 and WP2uvrA-, respectively.

The test material caused a visible reduction in the growth of the bacterial background lawns of all the tester strains both with and without metabolic activation, initially from 500 µg/plate. The test material was, therefore, tested up to either the maximum recommended dose level of 5000 µg/plate or the toxic limit, depending on the bacterial strain type.

No significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, at any dose level either with or without metabolic activation.

Applicant's summary and conclusion

Conclusions:
The test is negative, the test item is not mutagenic to bacteria.
Executive summary:

2,2'-Dihydroxy-4 -methoxybenzophenone has been tested according to OECD 471 and under GLP. No increase in the number of revertants was observed for the test substance tested up to cytotoxic or limit concentrations in any of the test strains either with or without metabolic activation. It is concluded that the test substance is not mutagenic to bacteria under the conditions of the test.