Dimolybdenum carbide

Endpoint summary

Description of key information

Sodium molybdate was tested negative for acute dermal and eye irritating properties according to OECD 404 and OECD 405. Sodium molybdate is used as read-across partner to Dimolybdenum carbide.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1990-06-25 to 1990-11-02

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. Sodium molybdate is used as read-across partner to Dimolybdenum carbide.

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: A. Smtith, Warlingham, Surrey
- Age at study initiation: 9 to 11 weeks
- Weight at study initiation: 2.2 to 2.6 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

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

water

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 g of Sodium Molybdate moistened with 0.5 mL of distilled water

Duration of treatment / exposure:

4 hours

Observation period:

4 days

Number of animals:

6 females

Details on study design:

TEST SITE
- Area of exposure: 2.5 cm²
- Type of wrap if used: elastic adhesive dressing "Elastoplast"

REMOVAL OF TEST SUBSTANCE
- Washing (if done): with water
- Time after start of exposure: 4 hours

SCORING SYSTEM:
Erythema and eschar formation:
0 - No erythrema
1 - Very slight erythema (barely perceptible)
2 - Well-defined erythema
3 - Moderate to severe erythema
4 - Severe erythema (beet redness) to slight eschar formation (injuries in depth)

Oedema formation:
0 - No oedema
1 - Very slight oedema (barely perceptible)
2 - Slight oedema (edges of area well-defined by definite raising)
3 - Moderate oedema (raised approximately 1 millimetre)
4 - Severe oedema (raised more than 1 millimetre and extending beyond the area of exposure)

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 0.5

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 0.5

Score:

0

Max. score:

0

Irritation parameter:

erythema score

Basis:

mean

Time point:

24 h

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

mean

Time point:

24 h

Score:

0

Max. score:

0

Irritation parameter:

erythema score

Basis:

mean

Time point:

48 h

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

mean

Time point:

48 h

Score:

0

Max. score:

0

Irritation parameter:

erythema score

Basis:

mean

Time point:

72 h

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

mean

Time point:

72 h

Score:

0

Max. score:

0

Irritant / corrosive response data:

No irritation

Other effects:

None

Table 1: Dermal reactions elicited by Sodium Molybdate
Rabbit number*		E = Erythema	Day
		O = Oedema	1**	2	3	4
2481		E	0	0	0	0
		O	0	0	0	0
2482		E	0	0	0	0
		O	0	0	0	0
2483		E	0	0	0	0
		O	0	0	0	0
2484		E	0	0	0	0
		O	0	0	0	0
2485		E	0	0	0	0
		O	0	0	0	0
2486		E	0	0	0	0
		O	0	0	0	0

*= only female animals were tested

**= approximately 30 minutes after removal of dressing

Interpretation of results:

not irritating

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

In conclusion, in an acute dermal irritation/corrosion study according to OECD 404, the read-across partner Sodium Molybdate was found to be non-irritating.

Executive summary:

In a primary dermal irritation study (OECD guideline 404), six female New Zealand white rabbits were dermally exposed to 0.5 g of Sodium Molybdate for 4 hours to a body surface area of 2.5 cm² under semi-occlusive conditions. Animals then were observed for 0.5, 24, 48 and 72 hours. Sodium Molybdate did not cause any skin effects and is considered under the conditions of this study as non toxic. Sodium Molybdate is used as read-across partner to Dimolybdenum carbide.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1990-06-25 to 1990-11-02

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. Sodium molybdate is used as read-across partner to Dimolybdenum carbide.

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

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

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 - Nacrous 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

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

0.33

Max. score:

0.66

Reversibility:

fully reversible within: 3d

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0.06

Max. score:

0.33

Reversibility:

fully reversible within: 2d

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

Interpretation of results:

not irritating

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

In conclusion, in an acute eye irritation/corrosion study according to OECD 405, the read-across partner 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.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

No data is available for Dimolybdenum carbide (target substance). Thus, available data from Sodium molybdate was used in a read-across approach. Due to a lower water solubility of Dimolybdenum carbide compared to Sodium molybdate the resulting bioavailability (toxicity potential) would also be expected to be lower. Therefore, the read across to the source substance Sodium molybdate is adequately protective. Details on the read-across rational are provided in section 13.

Sodium molybdate was tested negative for acute dermal and eye irritating properties according to OECD 404 and OECD 405. Based on the results from the read-across partner Sodium molybdate, Dimolybdenum carbide can be considered as not irritating to the skin and eye.

Justification for selection of skin irritation / corrosion endpoint:

GLP guideline study according to OECD guideline 404 conducted with Sodium molybdate.

Justification for selection of eye irritation endpoint:

GLP guideline study according to OECD guideline 405 conducted with Sodium molybdate.

Justification for classification or non-classification

The read across partner Sodium molybdate did not cause any skin and eye effects in an acute dermal and eye irritating study in accordance to OECD 404 and OECD 405. Based on the results from the read-across partner, no classification of Dimolybdenum carbide is warranted.