Molybdenum disilicide

Eye irritation

Administrative data

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990-06-25 to 1990-11-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Disodium molybdate

EC Number:

231-551-7

EC Name:

Disodium molybdate

Cas Number:

7631-95-0

Molecular formula:

MoO4.2Na

IUPAC Name:

Disodium tetraoxomolybdate

Specific details on test material used for the study:

- Name of test material (as cited in study report): Sodium molybdate
- Physical state: white crystalline powder
- Analytical purity: 46.03 % Molybdenum, 18.69% sodium
- Purity test date: 1990-06-06
- Storage condition of test material: at room temperature

Test animals / tissue source

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: A. Smith, Warlingham, Surrey and Froxfield Farms (U.K.) Ltd., Petersfield, Hampshire
- Age at study initiation: 11 to 13 weeks
- Weight at study initiation: 2.6 to 3.0 kg
- Housing: individually in metal cages with perforated floors
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 °C
- Humidity (%): 30 to 70 %
- Air changes (per hr): 19
- Photoperiod (hrs dark / hrs light): 12/12

Test system

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 100 mg of Sodium molybdate (the weight occupying a volume of 0.1 mL)

Duration of treatment / exposure:

A 100 mg amount of the test item was placed into the lower everted lid of one eye of each animal. The eyelids were then gently held together for one second before releasing. The contralateral eye remained untreated and served as a control.

Observation period (in vivo):

1, 24, 48, 72, 96 and 168 hours

Number of animals or in vitro replicates:

6 (4 males and 2 females)

Details on study design:

SCORING SYSTEM:
Cornea:
Opacity: degree of density (area most dense taken for reading)
0 - No ulceration or opacity
1 - Scattered or diffuse areas of opacity (other than slight dulling of normal lustre), details of iris clearly visible
2 - Easily discernible translucent areas, details of iris slightly obscured
3 - Nacreous areas, no details of iris visible, size of pupil barely discernible
4 - Opaque cornea, iris not discernible through the opacity

Area of cornea involved
1 - One quarter (or less) but not zero
2 - Greater than one quarter, but less than half
3 - Greater than half, but less than three quarter
4 - Greater than three quarters, up to whole area

Iris
0 - Normal
1 - Markedly deepened rugae, congestion, swelling, moderate circumcorneal hyperaemia or injection, any of these or combination of any thereof, iris still reacting to light (sluggish reaction is positive)
2 - No reaction to light, haemorrhage, gross destruction (any or all of these)

Conjunctivae
Redness (refers to palpebral and bulbar conjunctivae cornea and iris)
0 - Blood vessels normal
1 - Some blood vessels definitely hyperaemic (injected)
2 - Diffuse, crimson colour, individual vessels not easily discernible
3 - Diffuse, beefy red

Chemosis (lids and/or nictating membranes)
0 - No swelling
1 - Any swelling above normal (includes nictitating membranes)
2 - Obvious swelling with partial eversion of lids
3 - Swelling with lids about half-closed
4 - Swelling with lids more than half-closed

TOOL USED TO ASSESS SCORE:
handheld torch

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Results 2

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Results 3

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

0.33

Max. score:

0.66

Reversibility:

fully reversible within: 3d

Results 4

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0.06

Max. score:

0.33

Reversibility:

fully reversible within: 2d

Irritant / corrosive response data:

Eye irritation scores were recorded at 1, 24, 48, and 72 hours, and at 7 days after treatment. No corneal damage or iridial inflammation was seen throughout the observation period. A diffuse crimson-red colouration of the conjunctivae was seen one hour after instillation only in one animal. Mild conjunctival inflammation was observed in the remaining five animals. Conjunctival reactions had completely resolved in all animals one to three days after instillation.

Any other information on results incl. tables

Table 1: Mean values of each rabbit scored at 24, 48 and 72 hours after treatment with Sodium molybdate
Animal number		Opacity		Iritis		Conjunctival redness		Conjunctival oedema
2451 (male)		0		0		0.33		0
2523 (male)		0		0		0.33		0
2524 (male)		0		0		0.66		0.33
2525(male)		0		0		0.33		0
2526 (female)		0		0		0		0
2527 (female)		0		0		0.33		0

Applicant's summary and conclusion

Interpretation of results:

not irritating

Conclusions:

In conclusion, in an acute eye irritation/corrosion study according to OECD 405, Sodium molybdate is not an eye-irritant.

Executive summary:

In a primary eye irritation study (OECD 405), 100 mg of Sodium molybdate was instilled into the conjunctival sac of one eye of each of six young adult New Zealand White rabbits (four males and two females). Animals were observed for 7 days. Irritation was scored by the method of Draize. Only very mild conjunctival reactions were observed, which were fully reversible within 2-3 days. In this study, Sodium molybdate is not an eye irritant.