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Toxicological information

Acute Toxicity: oral

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acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1990-07-05 to 1990-07-19
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 401 (Acute Oral Toxicity)
Version / remarks:
adopted 24 February 1987
GLP compliance:
The study report states that the study was conducted in compliance with Good Laboratory Practice Standards, e.g. by the United Kingdom Compliance Programme, Department of Health & Social Security 1986 and subsequent revision, Department of Health, 1989.
Test type:
standard acute method
Limit test:

Test material

Constituent 1
Reference substance name:
Molybdenum sulfide (MoS2), roasted
EC Number:
EC Name:
Molybdenum sulfide (MoS2), roasted
Cas Number:
molybdenum sulfide (MoS2), roasted
Details on test material:
- Name of test material (as cited in study report): Technical molybdic oxide
- EC Name: molybdenum sulfide (MoS2), roasted
- Synonyms: roasted molybdenite concentrate
- Physical state: grey powder
- Analytical purity: contains 63.73 % Molybdenum, according to certificate of analysis
- Impurities (identity and concentrations): Certificate of analysis states 3.17 % SiO2 as the only major impurity (>1%)
- Purity test date: 1990-06-06
- Storage condition of test material: at room temperature

No further significant information was stated.

Test animals

other: CD
Details on test animals or test system and environmental conditions:

- Age at study initiation: approximately four to six weeks (main study)
- Weight at study initiation: weight range of 108 to 125 g (main study)
- Fasting period before study: Access to food was prevented overnight prior to dosing.
- Housing: housed in groups of up to five rats of the same sex in metal cages with wire mesh floors
- Diet (ad libitum): standard laboratory rodent diet (SDS LAD 1)
- Water (ad libitum): domestic potable water
- Acclimation period: eight days prior to the start of the main study

- Temperature (°C): mean daily minimum and maximum temperatures of the animal room were 22°C and 25°C respectively
- Humidity (%): mean daily relative humidity value was 60 % R.H.
- Air changes (per hr): approximately 15 air changes/hour
- Photoperiod (hrs dark / hrs light): 12 hour/12 hour

No further significant information on test animals was stated.

Administration / exposure

Route of administration:
oral: gavage
corn oil
Details on oral exposure:
Technical molybdic oxide was prepared at a concentration of 50 % w/v in corn oil and administered at a volume of 10.0 ml/kg bodyweight. The test substance was prepared on the day of dosing.

Treatment procedure:
The appropriate dose volume of the test substance was administered to each rat using a syringe and plastic catheter (8 choke). The day of dosing was designated Day 1.
Preliminary study: 126 mg/kg bodyweight
Main study: 5000 mg/kg bodyweight
No. of animals per sex per dose:
Preliminary study: two males/two females
main study: five males/ five females
Control animals:
Details on study design:
- Duration of observation period following administration: The animals on the preliminary and main studies were observed for 5 and 14 days respectively, after dosing. Test animals fasted approximately 4 hours after dosing.
- Frequency of observations and weighing: Preliminary study and main study: Animals were observed soon after dosing and at frequent intervals for the remainder of Day 1 (a period of six hours). On subsequent days the animals were observed once in the morning and again at the end of the experimental day. Clinical signs were recorded at each observation. Main study: The individual bodyweight was recorded on Days 1 (day of dosing), 8 and 15.
- Necropsy of survivors performed: yes
- Other examinations performed: Main study: The nature, severity, approximate time of onset and duration of each toxic sign. All animals on the main study were killed on Day 15 by carbon dioxide asphyxiation and were subjected to a macroscopic post mortem examination which consisted of opening the cranial, abdominal and thoracic cavities. The macroscopic appearance of all examined tissues was recorded, and all livers and kidneys were preserved in buffered 10 % formalin in order to satisfy any possible future requirement for further examination to these tissues.
No further information on study design were stated.
not stated

Results and discussion

Effect levels
Dose descriptor:
Effect level:
> 5 000 mg/kg bw
There were no deaths following a single oral dose of Technical molybdic oxide at 5000 mg/kg bodyweight.
Clinical signs:
Pilo-erection was observed in all rats within five minutes of dosing and throughout the remainder of Day 1. There were no other clinical signs and recovery, as judged by external appearance and behaviour, was complete by Day 4.
Body weight:
Slightly low bodyweight gains were recorded for the majority of rats on Day 8. Remaining rats achieved anticipated bodyweight gains on Day 8, and all rats achieved anticipated bodyweight gains during the second week of the study.
Gross pathology:
Terminal autopsy revealed no macroscopic abnormalities.

Any other information on results incl. tables

Prelimiary study:

The results of the preliminary study indicate that the acute lethal oral dose to rats of Technical molybdic oxide was greater than 126 mg/kg bodyweight. As a result of the limited toxicity seen at this dosage (pilo-erection was recorded for all rats on Day 1 only), a treatment level 5000 mg/kg bodyweight was decided upon for the main study.

Applicant's summary and conclusion

Interpretation of results:
not classified
Migrated information Criteria used for interpretation of results: EU
The acute lethal oral dose to rats of Technical molybdic oxide was found to be: greater than 5000 mg/kg bodyweight.