Octane-1-thiol

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:

1995-09-26 to 1995-12-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restriction because it is well-documented and generally follows OECD Guideline 471.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: E.C. Directive No. 92/69/E.E.C., Annex V, B14, 31st July 1992

GLP compliance:

yes (incl. QA statement)

Remarks:

Decret N 90-206 du 7 mars 1990 concernant les Bonnes Pratiques de Laboratoire (Ministere de l'Industrie et de l'Amenagement du Territoire), and OECD GLP

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Octane-1-thiol (CAS # 111-88-6)

IUPAC Name:

Octane-1-thiol (CAS # 111-88-6)

Details on test material:

- Test article name: n-octyl mercaptan (octane-1-thiol)
- CAS no.: 111-88-6
- Source: Elf Atochem Rotterdam B.V
- Batch 94-000605
- Purity 99.44%
- Impurities (identity and concentrations): Octanol (0.16%), Di-n-Octyl Disulfur (0.02%), Di-n-Octyl Sulfur (0.01), Octyl Mercaptan second (0.37%)
- Substance type: colourless liquid
- Container: smoked glass flask
- Date of Receipt: 1994-10-20
- Storage Conditions: room temperature and protected from light
- Expiration date of the lot/batch: after January 1996

Method

Target gene:

Salmonella typhimurium strains TA1535, TA 1537, TA98, TA 100, or TA 102

Species / strain

Species / strain / cell type:

other: S. typhimurium strains TA1535, TA 1537, TA98, TA 100, or TA 102

Details on mammalian cell type (if applicable):

- Type and identity of media: cryoprotective (1 mL nutrient broth and 0.09 mL Dimethylsulfoxide
- Properly maintained: yes

Additional strain / cell type characteristics:

other: one mutation In the histidine operon

Metabolic activation:

with and without

Metabolic activation system:

S9

Test concentrations with justification for top dose:

Without and without S-9: 3, 10, 30, 100, 300, 1000, or 3000 µg/plate

Vehicle / solvent:

Dimethylsulfoxide (DMSO), the test substance was freely soluble in the vehicle (DMSO) at 50 mg/ml.

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

other: sodium azide, 9-Aminoacridine, 2-Nitrofluorene, Mitomycin C, 2-Anthramine

Details on test system and experimental conditions:

METHOD OF APPLICATION: direct plate incorporation method


DURATION
- Preincubation period: 60 minutes
- Exposure duration:
- Expression time (cells in growth medium):
- Selection time (if incubation with a selection agent):
- Fixation time (start of exposure up to fixation or harvest of cells): 48 to 72 hours


SELECTION AGENT (mutation assays): S9


NUMBER OF REPLICATIONS: 3 plates per dose

Evaluation criteria:

A reproducible two-fold increase in the number of revertants compared with the vehicle controls, in any strain at any dose-level and/or evidence of a dose-relationship was considered as a positive result. Reference to historical data, or other considerations of biological relevance may also be taken into account in the evaluation of the data obtained.

Statistics:

no data reported

Results and discussion

Test results

Species / strain:

other: S. typhimurium strains: TA 1535, TA 1537, TA 98, TA 100 and TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: >100 µg/plate for the TA1535 and TA1537 strains; >1000 µg/plate for TA98, TA100 and TA102 strains.

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: None
- Other confounding effects: None


RANGE-FINDING/SCREENING STUDIES:
Without S9 mix:
3, 10, 30, 100, 300 µg/plate, for the four strains: TA 1535, TA 1537, TA 98, TA 100; 30, 100, 300, 1000, 3000 µg/plate, for the TA 102 strain. As slight toxicity was observed at the highest dose-level for the four strains (TA 1535, TA 1537, TA 98, TA 100) whereas important toxicity was noted for TA 102, the dose-levels were accordingly slightly increased or decreased for the second experiment: 10, 30, 100, 300, 1000 µg/plate.

With S9 mix:
3, 10, 30, 100, 300 µg/plate.



COMPARISON WITH HISTORICAL CONTROL DATA: The number of revertants in the vehicle controls was within the range of the historical data


ADDITIONAL INFORMATION ON CYTOTOXICITY:
Without S9 Mix:
Moderate to marked toxicity was observed at doses higher than 100 µg/plate for the TA 1535 and TA 1537 strains. Slight or moderate toxicity was noted at 1000 µg/plate for the TA 98, TA 100 and TA 102 strains.

With S9 Mix:
Slight (TA 98, TA 102) or moderate (TA 1535, TA 100) to strong toxicity (TA 1537) was observed at 1000 µg/plate.

Remarks on result:

other: other: strains: TA 1535, TA 1537, TA 98, TA 100 and TA 102

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

The top dose-level was selected according to the criteria specified in the international regulations: since the test substance was toxic, the top dose-level was based on the toxicity level, reduction of the number of revertants, and/or clearing of the bacterial lawn.

The selected dose-levels were: 
Without S9 mix: 
First experiment: 
3, 10, 30, 100, 300 µg/plate, for the four strains: TA 1535, TA 1537, TA  98, TA 100; 30, 100, 300, 1000, 3000 µg/plate, for the TA 102 strain.
As slight toxicity was observed at the highest dose-level
for the four strains (TA 1535, TA 1537, TA 98, TA 100)
whereas important toxicity was noted for TA 102, the dose levels were accordingly slightly increased or decreased for the second experiment: 10, 30, 100, 300, 1000 µg/plate. Moderate to marked toxicity was observed at doses higher than 100 µg/plate for the TA 1535 and TA 1537 strains.
Slight or moderate toxicity was noted at 1000 µg/plate for the TA 98, TA 100 and TA 102 strains.

With S9 mix: 
First experiment:
3, 10, 30, 100, 300 µg/plate.

Second experiment:
10, 30, 100, 300, 1000 µg/plate. Slight (TA 98, TA 102) or moderate (TA 1535, TA 100) to strong toxicity (TA 1537) was observed at 1000 µg/plate.

The test substance did not induce any significant increase in the number of revertants, with or without S9 mix, in any of the five strains.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative with and without metabolic activation

In a reverse gene mutation assay in bacteria, strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 of S. typhimurium were exposed to octane-1-thiol in dimethylsulfoxide at concentrations of 3, 10, 30, 100, 300, 1000, or 3000 µg/plate with and without metabolic activation using the plate-incorporation method. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of induced mutant colonies over background.

Executive summary:

In a reverse gene mutation assay in bacteria, strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 of S. typhimurium were exposed to octane-1-thiol in dimethylsulfoxide at concentrations of 3, 10, 30, 100, 300, 1000, or 3000 µg/plate with and without metabolic activation using the plate-incorporation method.

 

Ocatane-1 -thiol was tested up to insoluble concentration of 1000 μg/plate. Slight oily precipitation was noted at the 1000 and 333.3 μg/plate dose levels.  In the first study toxicity was noted at four of the five highest dose levels for the TA1535 and TA1537 strains and the two highest dose levels for TA98, TA100, and TA102 strains, the dose-levels were accordingly slightly increased or decreased for the second experiment. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of induced mutant colonies over background.

 

This study received a Klimisch score of 1 and was classified as reliable without restrictions because it was well-documented and generally followed OECD Guideline 471.