2,2-dimethyl-1,4,2-oxathiasilinan-6-one

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 January 2015 to 22 January 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

21 July 1997

Deviations:

yes

Remarks:

only pre-incubation method

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: JAPAN: The Notification stipulating the standard provided by the Minister of Health, Labour and Welfare of the Industrial Safety and Health Act Procedures of Mutagenicity Test Using Microorganisms and Evaluation of Test Results

Version / remarks:

01 September 1988
08 February 1999

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: JAPAN: Reverse Mutagenicity Test on Bacteria" of "Mutagenicity Test" stipulated in the "Testing Methods for New Chemical Substances

Version / remarks:

31 March 2011

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2,2-dimethyl-1,4,2-oxathiasilinan-6-one

EC Number:

851-441-8

Cas Number:

18163-71-8

Molecular formula:

C5H10O2SSi

IUPAC Name:

2,2-dimethyl-1,4,2-oxathiasilinan-6-one

Test material form:

liquid

Specific details on test material used for the study:

Lot number: 311001

Method

Target gene:

his operon

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Type and composition of metabolic activation system:
- source of S9 : S9 (Oriental Yeast) prepared from the liver of 7-week-old male SD rats administered with phenobarbital (one time at 30 mg/kg and three times at 60 mg/kg) and 5,6-benzoflavone (one time at 80 mg/kg) was used.
- method of preparation of S9 mix : One milliliter of S9 mix consisted of 8 µmol MgCl2, 33 µmol KCl, 5 µmol Glucose-6-phosphate, 4 µmol NADPH, 4 µmol NADH, 100 µmol sodium-phosphate buffer (pH 7.4) and 0.1 mL of S9.
- quality controls of S9: enzymatic activity

Test concentrations with justification for top dose:

Main test-1:
Without S9: 5000, 1250, 313, 78.1, 19.5, 4.88 µg/plate
With S9: 5000, 1250, 313, 78.1, 19.5, 4.88 µg/plate
Main test-2:
Without S9: 5000, 1250, 625, 313 µg/plate
With S9: 5000, 1250, 625, 313 µg/plate

Vehicle / solvent:

- Vehicle used: dehydrated DMSO
- Justification for choice of vehicle: The test substance solution of 50.0 mg/mL prepared with dehydrated DMSO was considered to be stable from the facts that there were no change in color, exothermic reaction nor gas generation at room temperature within 2 hours after preparation. Therefore, dehydrated DMSO was selected as a vehicle.

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-(2-Furyl)-3-(5-nitro-2-furyl)acrylamide

Remarks:

without metabolic activation

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

without metabolic activation

Controls 3

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: ICR-191

Remarks:

without metabolic activation

Controls 4

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-Aminoanthracene

Remarks:

with metabolic activation

Details on test system and experimental conditions:

NUMBER OF REPLICATIONS:
- Number of cultures per concentration: triplicate
- Number of independent experiments : 2

METHOD OF TREATMENT/ EXPOSURE:
- Test substance added: preincubation

TREATMENT AND HARVEST SCHEDULE:
- Preincubation period: 20 min
- Exposure duration/duration of treatment: 48 hours

METHODS FOR MEASUREMENT OF CYTOTOXICITY
- Method: background growth inhibition

Evaluation criteria:

The test substance was judged to be positive when the number of revertant colonies increased to twice or more than that in the negative control and when the responses were dose-related and/or reproducible. The other cases were judged to be negative. No statistical methods were used.

Statistics:

None

Results and discussion

Test results

Test results 1

Key result

Species / strain:

other: S.typhimurium TA98, TA100, TA1535, TA 1537

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

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

E. coli WP2 uvr A

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

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

STUDY RESULTS
Ames test:
- Signs of toxicity : none
- Individual plate counts : Please refer to the attached background material (Table # 1 and 2)
- Mean number of revertant colonies per plate and standard deviation : Please refer to the attached background material (Table # 1 and 2)

HISTORICAL CONTROL DATA
- Positive historical control data: Please refer to the attached background material (Appendix 1)
- Negative (solvent/vehicle) historical control data: Please refer to the attached background material (Appendix 1)

Applicant's summary and conclusion

Conclusions:

The test item had no ability to induce mutations in a pre-incubation method with Salmonella typhimurium strains TA100, TA1535, TA98 and TA1537 and Escherichia coli strain WP2 uvrA in the presence and absence of a metabolic activation system (S9 mix) under the present test conditions.

Executive summary:

The ability of the test item to induce mutations was investigated using Salmonella typhimurium strains TA100, TA1535, TA98 and TA1537 and Escherichia coli strain WP2 uvrA with a pre-incubation method in the presence and absence of a metabolic activation system (S9 mix). The mutagenicity of the test item was judged to be negative because the number of revertant colonies in the test substance treatment groups was less than twice that in the negative control for all tester strains regardless of the presence or absence of S9 mix. The numbers of the revertant colonies in the positive controls were above twice that in the negative controls. The test results showed that the numbers of revertant colonies in the negative and positive controls were within the range of the historical data at the testing facility. It was also confirmed that the test system was free from bacterial contamination, which declares the test results to be valid. It was concluded that the test item had no ability to induce mutations under the present test conditions.