1,3-dihydro-5-methoxy-2H-benzimidazole-2-thione

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 October 1984 - 14 November 1984

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1984

Report date:

1985

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1,3-dihydro-5-methoxy-2H-benzimidazole-2-thione

EC Number:

253-326-2

EC Name:

1,3-dihydro-5-methoxy-2H-benzimidazole-2-thione

Cas Number:

37052-78-1

Molecular formula:

C8H8N2OS

IUPAC Name:

5-methoxy-1,3-dihydro-2H-benzimidazole-2-thione

Specific details on test material used for the study:

Batch: 13M 2163
Assay: 98,8%

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

On arrival at the laboratory and before assignment to this study, the rats were subjected to a visual inspection. Any animal showing signs of disability was excluded. The animals were acclimatised to laboratory conditions for at least 3 days.
The rats were kept 2 in a cage in transparent Macrolon® cages, measuring approximately 40x20 cm.
The air was changed about 15 times per hour via a centrally placed air intake and two peripheral ventilators. Target values for temperature and humidity were 18-22 degrees C and 40-70%, respectively. Recorded values were within the stipulated limits.

The animal rooms were illuminated by artificial light from fluorescent tubes on a 12-hour light/dark cycle.

The animals were fasted overnight (approximately 16 hours) before dosing and for approximately 3 hours after dosing, but otherwise they had free access to feed. Food consumption during the study was not measured. The animals had free access to municipal tap water for human consumption throughout the study.
The feed is analysed regularly for nutrients and both feed and water regularly for chemical and microbial contaminants, according to current written standard operation procedures.

Administration / exposure

Route of administration:

oral: unspecified

Vehicle:

not specified

Doses:

250, 500 and 750 mg/kg body weight

No. of animals per sex per dose:

The study included 3 groups of animals, with 6 males in each.

Control animals:

no

Details on study design:

All animals were weighed immediately before dosing. Surviving animals were weighed on days 1, 2, 3, 4, 7 and 14.
The animals were observed and clinical signs and mortality recorded at least once during the intervals 0-1,1-3, 3-6 and 6-24 hours and then daily up to 14 days after dosing.

Results and discussion

Preliminary study:

. In the dose finding phase the results showed that it was not relevant to include a dose higher than 750 mg/kg in the main study.

Effect levels

Key result

Sex:

male

Dose descriptor:

approximate LD50

Effect level:

> 750 - <= 1 000 mg/kg bw

Mortality:

No deaths occurred at the dose levels 250 and 500 mg/kg. 2 of 6 animals died on day 2 at the dose level 750 mg/kg

Applicant's summary and conclusion

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

Evident toxicity in rats at a dose of 750 - 1,000 mg/kg