2,6-dichlorobenzoxazole

Genetic toxicity: in vitro

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:

04 June - 19 July 2002

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2,6-dichlorobenzoxazole

EC Number:

222-818-9

EC Name:

2,6-dichlorobenzoxazole

Cas Number:

3621-82-7

Molecular formula:

C7H3Cl2NO

IUPAC Name:

2,6-dichloro-1,3-benzoxazole

Details on test material:

- Name of test material (as cited in study report): 2,6-Dichlorobenzoxazol
- Physical state: colourless to yellowish melt
- Analytical purity:99.4%
- Lot/batch No.: 27.03.02/ LB 227 (Op. #25/26)
- Expiration date of the lot/batch: 27 September 2002
- Stability under test conditions: Is guaranteed for 4 hours in DMSO by HPLC analysis
- Storage condition of test material: at approximately 20 °C in a fume cupboard

Method

Target gene:

Histidine operon (Salmonella strains)
Tryptophan operon (E. Coli)

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Additional strain / cell type characteristics:

not applicable

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254 induced S9-fraction from rat liver

Test concentrations with justification for top dose:

Main plate incorporation test
with and without activation: 50, 160, 500, 1600 and 5000 μg/plate (all bacteria strains)

Repeat plate incorporation test and main preincubation test
with and without metabolic activation:
1.6, 5, 16, 50, 160 and 500 μg/plate (all Salmonella typhimurium strains)
5, 16, 50, 160, 500 and 1600 μg/plate (Escherichia coli WP2 uvrA)

Repeat preincubation test
without metabolic activation:
1.6, 5, 16, 50, 160 and 500 μg/plate (Escherichia coli WP2 uvrA)

Controls

Controls 1

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Controls 2

Positive controls:

yes

Remarks:

with metabolic activation

Positive control substance:

other: 2-aminoanthracene

Remarks:

For all strains

Controls 3

Positive controls:

yes

Remarks:

without metabolic activation

Positive control substance:

sodium azide

Remarks:

strain TA 100 and TA 1535

Controls 4

Positive controls:

yes

Remarks:

without metabolic activation

Positive control substance:

9-aminoacridine

Remarks:

strain TA 1537

Controls 5

Positive controls:

yes

Remarks:

without metabolic activation

Positive control substance:

2-nitrofluorene

Remarks:

strain TA 98

Controls 6

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

Remarks:

strain WP2uvrA Migrated to IUCLID6: without metabolic activation

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at concentrations of 160 μg/plate and above

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

in a dose range of 500 to 1600 μg/plate

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

Executive summary:

2,6-Dichlorobenzoxazol was tested for mutagenicity in two standard plate incorporation tests and in one preincubation test (each in the absence and in the presence of a metabolizing system) under GLP and according to OECD TG 471. In the main plate incorporation test, the substance was tested in bacteria strains TA 100, TA 1535, TA 1537 and TA 98 of S. thyphimurium and with E. Coli WP2uvrA at concentrations of 50, 160, 500, 1600 and 5000 μg/plate. Because of toxicity in the main plate incorporation test dose levels of 1.6, 5, 16, 50, 160 and 500 μg/plate (S. typhimurium tester strains) and dose levels of 5, 16, 50, 160, 500 and 1600 μg/plate

(E. Coli WP2 uvrA) were chosen for the second plate incorporation test and the main preincubation test. For the repeat preincubation test dose levels from 1.6 to 500 μg/plate were chosen in the absence of metabolic activation with the tester strain WP2 uvrA. Control plates without mutagen showed that the number of spontaneous revertant colonies was within the laboratory’s historical control range. All the positive controls showed the expected increase in the number of revertant colonies. There was no evidence of induced mutant colonies over background. In conclusion it can be stated that 2,6-Dichlorobenzoxazol is not mutagenic in this bacterial mutation test at any dose level either in the absence or presence of an exogenous metabolic activation system.