Molybdenum dioxide

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990-06-25 to 1990-07-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline study under GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

no

GLP compliance:

yes

Remarks:

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:

yes

Test material

Test material information

Constituent 1

Reference substance name:

disodium molybdate

IUPAC Name:

disodium molybdate

Constituent 2

Reference substance name:

7631-95-0

Cas Number:

7631-95-0

IUPAC Name:

7631-95-0

Constituent 3

Reference substance name:

Disodium molybdate

EC Number:

231-551-7

EC Name:

Disodium molybdate

Cas Number:

7631-95-0

Molecular formula:

Na2MoO4

IUPAC Name:

231-551-7

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): sodium molybdate
- Physical state: white crystalline powder
- Analytical purity: > 98.8% (calculated based on Molybdenum content of 46.03%)
- Impurities (identity and concentrations): no relevant impuritites were stated (>1%)
- Purity test date: 1990-06-06
- Storage condition of test material: At room temperature

No further significant information on test material was stated.

Test animals

Species:

rat

Strain:

other: CD

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: approximately seven to ten weeks
- Weight at study initiation: 216 to 262 g
- Housing: housed individually in metal cages with wire mesh floors. Each cage was identified by a coloured label displaying the dose level, study schedule number and the initials of the study director. Each animal was identified by cage number and ear punching.
- Diet (ad libitum): standard laboratory rodent diet (SDS LAD 1)
- Water (ad libitum): domestic quality potable water
- Acclimation period: 12 days

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

No further significant information on test animals was stated.

Administration / exposure

Type of coverage:

occlusive

Vehicle:

water

Details on dermal exposure:

Sodium molybdate was prepared at a concentration of 177.8 % w/v in distilled water and administered at a volume of 1.12 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 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.

no other significant details stated.

Duration of exposure:

24-hour exposure period

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5 males, 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- 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 scored according a scoring system.

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 8raised approximately 1 millimetre) = 3
serve oedema (raised more than 1 millimetre and extending beyond the area of exposure) = 4

Individual bodyweights of rats was 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 requirements for further examination of these tissues.

No further significant details stated.

Statistics:

no data

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Remarks on result:

other: There were no signs of dermal irritation to any of the application sites.

Mortality:

No deaths following a single dose of Sodium molybdate at 2000 mg/kg bodyweight.

Clinical signs:

other: No signs of systemic reaction to treatment.

Gross pathology:

No results stated.

Other findings:

No further findings.

Applicant's summary and conclusion

Interpretation of results:

not classified