Registration Dossier
Registration Dossier
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EC number: 200-837-3 | CAS number: 75-08-1
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:
- 1993-05-12 to 1993-07-23
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: This study received a Klimisch score of 2 and was classified as reliable with restrictions because it closely follows OECD 471 guidelines.
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 1 993
- Report date:
- 1993
Materials and methods
Test guideline
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 471 (Bacterial Reverse Mutation Assay)
- Deviations:
- yes
- Remarks:
- Unlike what is recommended in OECD 471, some samples were incubated for 24 hours, instead of the recommended 48-72 hours. Study does not include E. coli WP2 uvrA, or E. coli WP2 uvrA (pKM101), or S. typhimurium TA102, as recommended.
- GLP compliance:
- not specified
- Type of assay:
- bacterial reverse mutation assay
Test material
- Reference substance name:
- Ethanethiol
- EC Number:
- 200-837-3
- EC Name:
- Ethanethiol
- Cas Number:
- 75-08-1
- Molecular formula:
- C2H6S
- IUPAC Name:
- ethanethiol
- Details on test material:
- - Name of test material (as cited in study report): ethyl mercaptan (ethanethiol)
Constituent 1
Method
- Target gene:
- Histidine
Species / strain
- Species / strain / cell type:
- S. typhimurium, other: TA 1535, TA 1537, TA 1538, TA 98 and TA 100
- Details on mammalian cell type (if applicable):
- - Type and identity of media: Nutrient agar
- Properly maintained: yes - Additional strain / cell type characteristics:
- not specified
- Metabolic activation:
- with and without
- Metabolic activation system:
- S-9 mix from Arcolor 1254- induced rat liver (5%)
- Test concentrations with justification for top dose:
- 0, 0.05, 0.1, 0.5, 1, and 2.5% (V/V)
2.5 % = 65 µl/plate
1 % = 26 µl/plate
0.5 % = 13 µl/plate
0.1 % = 2.6 µl/plate
0.05 % = 1.3 µl/plate - Vehicle / solvent:
- No data reported
- Vehicle(s)/solvent(s) used: DMSO and phosphate buffer
Controls
- Untreated negative controls:
- yes
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- not specified
- Positive controls:
- yes
- Positive control substance:
- other: Without metabolic activation- Na azide (TA100, TA1535); 2- nitrofluorene (TA98); 9-aminoacridine (TA1537). With metabolic activation- 2-aminoanthracene (TA100, TA1538, TA1535, TA1537, TA98)
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: in agar (plate incorporation)
DURATION
- Preincubation period: No data reported
- Exposure duration: 24 and 48 hours
- Expression time (cells in growth medium): 24 hours after 24-hour exposure; the cultures were incubated for 48 hours with the test material during the 48-hour exposure
- Selection time (if incubation with a selection agent): No data reported
- Fixation time (start of exposure up to fixation or harvest of cells): No data reported
SELECTION AGENT (mutation assays): No data reported
SPINDLE INHIBITOR (cytogenetic assays): No data reported
STAIN (for cytogenetic assays): No data reported
NUMBER OF REPLICATIONS: triplicate
NUMBER OF CELLS EVALUATED:No data reported
DETERMINATION OF CYTOTOXICITY
Bacterial background lawn and number of Histidine revertant colonies per plate
OTHER EXAMINATIONS:
No data reported - Evaluation criteria:
- Revertant colonies were counted and compared to the number of spontaneous revertant colonies on control plates.
- Statistics:
- No data reported
Results and discussion
Test results
- Species / strain:
- S. typhimurium, other: TA 1535, TA 1537, TA 1538, TA 98 and TA 100
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- valid
- Positive controls validity:
- valid
- Additional information on results:
- TEST-SPECIFIC CONFOUNDING FACTORS
No data reported
RANGE-FINDING/SCREENING STUDIES: A range finding toxicity study was performed using TA98 and TA100 with and without metabolic activation to determine the metabolic activation to determine the concentration range to be used in the main genotoxicity study.
Any other information on results incl. tables
Table 1. Mean number of histidine revertant colonies per plate, with and without metabolic activation
Concentration % |
TA 98 |
TA 100 |
TA 1535 |
TA 1537 |
TA 1538 |
|||||
+MA |
-MA |
+MA |
-MA |
+MA |
-MA |
+MA |
-MA |
+MA |
-MA |
|
DMSO |
35.7 |
31.3 |
137.3 |
172.3 |
10.7 |
13.3 |
7.5 |
6.7 |
19.0 |
11.3 |
Spontaneous revertants |
42.7 |
31.7 |
169.3 |
173.3 |
11.0 |
9.3 |
11.3 |
8.3 |
12.7 |
13.0 |
Dichloromethane 7.5 % |
|
487.3 |
|
2277.3 |
|
35.3 |
|
6.7 |
|
4.0 |
Positive control |
959.5 |
464.5 |
538.0 |
639.0 |
309.0 |
825.0 |
50.5 |
1158.5 |
192.5 |
223.5 |
Ethyl mercaptan 0.05 % |
39.7 |
29.0 |
148.3 |
131.0 |
10.7 |
9.3 |
6.7 |
7.0 |
13.7 |
6.7 |
Ethyl mercaptan 0.1 % |
32.3 |
22.0 |
157.0 |
154.7 |
7.3 |
7.7 |
11.3 |
9.3 |
15 |
12.0 |
Ethyl mercaptan 0.5 % |
34.7 |
32.7 |
114.3 |
18.7 |
8.7 |
0.7 |
5.0 |
1.7 |
7.7 |
7.3 |
Ethyl mercaptan 1 % |
31.0 |
23.3 |
0.0 |
0.3 |
0.0 |
0.0 |
0.0 |
0.0 |
2.7 |
5.3 |
Ethyl mercaptan 2.5 % |
0.0 |
0.0 |
0.0 + |
0.0+ |
0.0+ |
0.0+ |
0.0 |
0.0+ |
0.0+ |
0.0 |
MA - metabolic activation
+ - reduced background lawn growth
Applicant's summary and conclusion
- Conclusions:
- Interpretation of results (migrated information):
negative
There was no evidence of induced S. typhimurium mutant colonies over background in the reverse gene mutation assay in bacteria. - Executive summary:
In a reverse gene mutation assay in bacteria, five strains of S. typhimurium (TA1535, TA1537, TA1538, TA98 and TA100) were exposed to ethanethiol at 0.05, 0.1, 0.5, 1, and 2.5% concentrations.
Ethanethiol was tested up to cytotoxic concentrations. In a preliminary toxicity assay, a clear toxic effect was observed after 24 hours in the in the histidine positive colonies, primarily in TA98 at greater than and equal to 5% and TA 100 at greater then or equal to 1%, with and without metabolic activation. There was no evidence of induced S. typhimurium mutant colonies, with or without metabolic activation, over background in the reverse gene mutation assay in bacteria. The positive controls induced the appropriate responses in the corresponding strains.
This study received a Klimisch score of 2 and was classified as reliable with restrictions because it closely follows OECD 471 guidelines.
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