Sodium methanethiolate

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Data source

Reference

Reference 1

Reference Type:

review article or handbook

Title:

SIDS Dossier

Author:

OECD

Year:

2008

Bibliographic source:

OECD SIDS Dossier - sodium methanethiolate

Reference 2

Reference Type:

other: unpublished study report

Title:

Unnamed

Year:

1989

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Version / remarks:

adopted 1981

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Sodium methanethiolate

EC Number:

225-969-9

EC Name:

Sodium methanethiolate

Cas Number:

5188-07-8

Molecular formula:

CH4S.Na

IUPAC Name:

sodium methylsulfanide

Test material form:

liquid

Specific details on test material used for the study:

- Test article name : Sodium methylmercaptide
- CAS NR: 5188-07-8
- Origin: Atochem, Pilote UDL-AE no. 83562
- Batch: 897016
- Composition: Sodium methylmercaptide: 19.9% solution in water, Na2S: 0.30%, Free NaOH: 1.1%, releasable NaOH: 12.75%

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

All animals were fasted before treatment.

Administration / exposure

Route of administration:

oral: unspecified

Vehicle:

water

Details on oral exposure:

MAXIMUM DOSE VOLUME APPLIED: In the first assay, the test substance (19.9% solution in water) was administered at a volume of 2.05 mL/kg bw. In the second assay, the test substance in aqueous solution was administered at a volume of 10 mL/kg bw.

Doses:

First assay: 2000 mg/kg bw
Second assay: 400, 620, 950 and 1400 mg/kg bw

No. of animals per sex per dose:

First assay: 5 animals per sex and dose
Second assay: 5 males each for the dose group 1400 and 400 mg/kg bw; 5 animals per sex for the dose group 620 and 950 mg/kg bw

Control animals:

no

Details on study design:

In a first assay, Sodium methylmercaptide (19.9% solution in water), was administered in its original form to a group of 10 Sprague-Dawley rats (5 males and 5 females) at a dose level of 2000 mg/kg bw at a volume of 2.05 mL/kg taking into consideration that the specific gravity (SG) of the test substance was 0.977. In a second assay, the test substance was administered at the dose levels of 400, 620, 950 and 1400 mg/kg bw to 4 groups of 5 males and at the dose levels of 620 and 950 mg/kg bw to 2 groups of 5 females. The mortality, general behaviour and bodyweight gain of the animals were observed for a period of 14 days after the single administration of the test substance. A necropsy was performed on each animal found dead or sacrificed at the end of the study.

Statistics:

The LD50 in males was calculated according to Finney's method.

Results and discussion

Effect levels

Effect levels 1

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

116 mg/kg bw

Based on:

test mat.

Remarks on result:

other:

Remarks:

pure test substance

Effect levels 2

Sex:

male/female

Dose descriptor:

LD50

Effect level:

581 mg/kg bw

Based on:

test mat.

Remarks on result:

other:

Remarks:

formulated test substance: 19.9% in water

Mortality:

The mortality was respectively 20%, 40%, 100%, 100% and 100% at the dose levels of 400, 620, 950, 1400 and 2000 mg/kg bw in the males and 60%, 100% and 80% at the dose levels of 620, 950 and 2000 mg/kg bw in the females. Mortality was recorded within minutes of treatment.

Clinical signs:

A significant decrease in spontaneous activity, dyspnea at the dose levels of 400 and 620 mg/kg bw, tonico-clonic convulsions at the dose levels of 950 and 1400 mg/kg bw before death of the rats, and ataxia and coma at the dose level of 2000 mg/kg bw were the main clinical signs recorded.

Body weight:

The body weight gain of the surviving animals was normal at the dose level of 400 mg/kg bw and slackened off slightly until D5 at 620 and 2000 mg/kg bw.

Gross pathology:

An abnormal red colouration of the stomach was observed during the macroscopic examination of all animals from all dose levels found dead during the study. The necropsy performed on animals sacrificed at the end of the study revealed no macroscopic abnormalities.

Applicant's summary and conclusion

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

Based on the results, the oral LD50 was determined to be 116 mg/kg bw. Thus, the substance meets the criteria of the CLP Regulation 1272/2008 for being classified as Acute Tox. 3, H301.

Executive summary:

In an acute oral toxicity study (OECD 401), Sprague-Dawley rats (5 animals per sex) were given a single oral dose of 2000 mg/kg bw of Sodium methanethiolate (19.9% solution in water) in a first assay. In a second assay, the test substance was administered at the dose levels of 400, 620, 950 and 1400 mg/kg to 4 groups of 5 males and at the dose levels of 620 and 950 mg/kg to 2 groups of 5 females. The animals were observed for 14 days. The mortality was respectively 20%, 40%, 100%, 100% and 100% at the dose levels of 400, 620, 950, 1400 and 2000 mg/kg bw in the males and 60%, 100% and 80 % at the dose levels of 620, 950 and 2000 mg/kg bw in the females. Furthermore, all animals showed signs of toxicity. A significant decrease in spontaneous activity, dyspnea at the dose levels of 400 and 620 mg/kg bw, tonico-clonic convulsions at the dose levels of 950 and 1400 mg/kg bw before death of the rats, and ataxia and coma at the dose level of 2000 mg/kg bwwere the main clinical signs recorded. At necropsy, an abnormal red colouration of the stomach was observed during the macroscopic examination of all animals from all dose levels found dead during the study. However, the necropsy performed on animals sacrificed at the end of the study revealed no macroscopic abnormalities.

Based on the results, the oral LD50 for both sexes using the formulated test substance (19.9% in water) was determined to be 581 mg/kg bw and the oral LD50 after recalculation towards the pure test substance was determined to be 116 mg/kg bw in male and female rats. Thus, the substance meets the criteria of the CLP Regulation 1272/2008 for being classified as Acute Tox. 3, H301.