Ethyl methyl sulphide

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

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:

Ethyl methyl sulphide

EC Number:

210-868-4

EC Name:

Ethyl methyl sulphide

Cas Number:

624-89-5

Molecular formula:

C3H8S

IUPAC Name:

(methylsulfanyl)ethane

Details on test material:

Source: Elf Atochem, RDAM
Batch: MES 2611-11933
Purity: 98.4%

Method

Target gene:

Histidine reversion

Species / strain

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

Liver microsomal fraction (S9 fraction) of rats induced with Aroclor 1254

Test concentrations with justification for top dose:

Experiment without S9:
. 312.5, 625, 1250, 2500 and 5000 µg/plate: for all tester strains in both experiments except for the TA 1537 and TA 98 strains in the second experiment,
. 156.25, 312.5, 625, 1250 and 2500 µg/plate: for the TA 98 and TA 1537 strains in the second experiment.
Experiments with S9 mix:
. 312.5, 625, 1250, 2500 and 5000 µg/plate: for all tester strain.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: Without S9 mix: .1 µg/plate of sodium azide (NaN3): TA 1535 and TA 100 strains. 50 µg/plate of 9-Aminoacridine (9AA): TA 1537 strain. 0.5 µg/plate of 2-Nitrofluorene (2NF): TA 98 strain. 0.5 µg/plate of Mitomycin C (MMC): TA 102 strain. With S9 mix: 2 µ

Details on test system and experimental conditions:

A preliminary toxicity test was performed to define the dose-levels of ETHYLMETHYL SULFIDE to be used for the mutagenicity study. The test substance was then tested in two independent experiments, with and without a metabolic activation system, the S9 mix, prepared from a liver microsomal fraction (S9 fraction) of rats induced with Aroclor 1254. Both experiments were performed according to the direct plate incorporation method except for the second test with S9 mix, which was performed according to the preincubation method (60 minutes, 37°C). Five strains of bacteria Salmonella typhimurium: TA 1535, TA 1537, TA 98, TA 100 and TA 102 were used. Each strain was exposed to five dose-levels of the test substance (three plates/dose-level). After 48 to 72 hours of incubation at 37°C, the revertant colonies were scored. The evaluation of the toxicity was performed on the basis of the observation of the decrease in the number of revertant colonies and/or a thinning of the bacterial lawn.

Results and discussion

Test results

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

>= 2500 µg/ml

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

Since the test substance was freely soluble and almost non-toxic in the preliminary test, the highest dose-level for the first experiment was 5000 µg/plate, according to the criteria specified in the international guidelines. A slight emulsion was sometimes observed in the Petri plates when scoring the revertants at 5000 µg/plate.
Without S9, a slight to marked toxicity was noted (except for the TA 102 strain), depending on the tester strain and the dose-level. The test substance did no induce any noteworthy increase in the number of revertants, in both experiments, in any of the five strains.

With S9, no or slight to moderate toxicity was noted, depending on the tester strain and the dose-level. The test did not induce any noteworthy increase in the number of revertants, in both experiments, in any of the five strains.

The number of reverants for the vehicle and positive controls was as specified in the acceptance criteria. The study was therefore considered valid.

Applicant's summary and conclusion

Conclusions:

ETHYLMETHYL SULFIDE does not show mutagenic activity in the bacterial reverse mutation test with Salmonella typhimurium.

Executive summary:

In a reverse gene mutation assay in bacteria (# OECD 471, GLP), ethyl methyl sulfide was tested in the bacterial reverse mutation assay (OECD TG 471) with Salmonella typhimurium TA98, TA100, TA102, TA1535, and TA1537 at concentrations up to 5000 µg/plate with and without metabolic activation. The solvent was dimethylsulfoxide (DMSO).  Slight cytotoxicity was observed at concentrations >= 2500 µg/plate. Positive controls produced the expected result. Ethyl methyl sulfide was not mutagenic under the conditions of the assay.