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Acute Toxicity: dermal

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acute toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1990-06- 25 to 1990-07-09
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 402 (Acute Dermal Toxicity)
Version / remarks:
adopted 24 Februaury 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 disulfide (MoS2), roasted
molybdenum disulfide (MoS2), roasted
Constituent 2
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 disulfide (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: room temperature

No further significant information on test material was stated.

Test animals

other: CD
Details on test animals or test system and environmental conditions:
- Age at study initiation: approximately 7 to 10 weeks
- Weight at study initiation: 203 to 253 g prior to dosing
- Housing: housed individually in metal cages with wire mesh floors
- Diet (ad libitum): standard laboratory rodent diet (SDS LAD 1)
- Water (ad libitum): domestic quality potable water
- Acclimation period: 12 days prior to the start of the study

- Temperature (°C): mean daily minimum and maximum temperatures of the animal room were 22°C and 24°C respectively
- Humidity (%): mean daily relative humidity value was 60% RH
- Air changes (per hr): approximatley 15 air changes/hour
- Photoperiod (hrs dark / hrs light): 12 h/12h

No further significant details stated.

Administration / exposure

Type of coverage:
Details on dermal exposure:
Technical molybdic oxide was prepared at a concentration of 266,7% w/v in distilled water and administered at a volume of 0.75 ml/kg. The test substance was prepared on the day of dosing. One day prior to treatment hair was removed from the dorso-lumbar region of each rat with electric clippers exposing an area equivalent to 10% of the total body surface. No shaving or chemical depilation was used.
The test substance was applied by spreading it evenly over the prepared skin. The treated area (approximately 50 X50 mm) was then promptly covered with gauze which was held in place with an impermeable dressing encircled firmly around the trunk.
At the end of the 24-hour exposure period, the dressings were carefully removed and the treated area of skin decontaminated by washing in warm (30°- 40° C) water and blotting dry with absorbent paper. The day of dosing was designated Day 1.

No other significant details stated.

Duration of exposure:
24-hour exposure period
2000 mg/kg bodyweight
No. of animals per sex per dose:
5 males, 5 females
Control animals:
Details on study design:
- Duration of observation period following administration: 14 days after dosing
Frequency of observations and weighing: Animals were observed soon after dosing and at frequent intervals for the remainder of day 1 (a period of four 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. The treated areas of skin were examined daily for signs of dermal irritation and assessed according to the following arbitrary scoring system:

Erythema and Eschar Formation:
no erythema = 0
slight erythema = 1
well-defined erythema = 2
moderate erythema = 3
serve erythema (beet redness) to slight eschar formation (injuries in depth) = 4

Oedema Formation:
no oedema = 0
slight oedema = 1
well-defined oedema (area well-defined by definite raising) = 2
moderate oedema (raised approximately 1 millimetre) = 3
severe oedema (raised more than 1 millimetre and extending beyond the area of exposure) = 4

Individual bodyweights of rats were recorded on Days 1 (day of dosing), 8 and 15.

- Necropsy of survivors performed: yes
- Other examinations performed: The nature, severity, approximate time of onset and duration of each toxic sign were recorded. All animals on the study were killed on Day 15 by cervical dislocation and were subjected to a macroscopic post mortem examination which consisted of opening the 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 examination of these tissues.

No further significant information on study design were stated.
no data

Results and discussion

Effect levels
Dose descriptor:
Effect level:
> 2 000 mg/kg bw
Remarks on result:
other: There were no signs of dermal irritation at any of the application sites.
There were no deaths following a single dermal dose of Technical molybdic oxide at 2000 mg/kg bodyweight.
Clinical signs:
There were no signs of systemic reaction to treatment.
Body weight:
Slightly low bodyweight gains were recorded for three females on Day 8, and for one male on Day 15. Anticipated bodyweight gains were recorded for the male on Day 8 and the females on Day 15, whilst all other rats achieved anticipated bodyweight gains throughout the study.
Gross pathology:
Terminal autopsy revealed no macroscopic abnormailites.

Applicant's summary and conclusion

Interpretation of results:
not classified
Migrated information Criteria used for interpretation of results: EU