Niobium carbide

Endpoint summary

Description of key information

Niobium pentoxide was tested for its dermal and eye irritation potential in OECD guideline studies 404 and 405, respectively. The substance is neither a dermal irritant nor an eye irritant.

This information is used in a read-across approach for the assessment of niobium 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:

2000-07-25 to 2000-12-18

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. Niobium pentoxide data are used in a read-across approach for the assessment of niobium carbide.

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan UK Ltd., Bicester, Oxon, England.
- Age at study initiation: at least 12 weeks
- Weight at study initiation: 2.4 – 2.8 kg

Housing:
- Diet (e.g. ad libitum): standard laboratory rabbit diet (Special Diet Services STANRAB (P) SQC pellet)
- Water (e.g. ad libitum):ad libitum
- Acclimation period: 12 days
- Sex: males

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 +/- 2
- Humidity (%): 30 - 70
- Photoperiod (hrs dark / hrs light):12/12

Type of coverage:

semiocclusive

Preparation of test site:

other: clipped with electrical clipper

Vehicle:

water

Controls:

not required

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit):0.5 g moistened with water ad injectionem
VEHICLE
Aqua ad injectionem

Duration of treatment / exposure:

4h

Observation period:

72 hours after patch removal

Number of animals:

3

Details on study design:

Approximately 0.5 g of the test substance was applied under a 2-ply 25mm x 25mm gauze pad, which had been moistened with 0.5 mL distilled water, to one intact skin on each animal.
Each treatment site was covered with “Electroplast” elastic adhesive dressing for four hours. The animals were not restrained during the exposure period and were returned to their cages immediately after treatment.
At the end of the exposure period, the semi-occlusive dressing and gauze pad were removed and the treatment site was washed with warm water (36 °C) to remove any residual test substance. The treated area was blotted dry with absorbent paper.

SCORING SYSTEM: according to OECD 404

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritant / corrosive response data:

At all evaluation time points the individual scores for erythema and oedema were 0.

Other effects:

none

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In a primary dermal irritation study according to OECD 404 niobium pentoxide was not irritating.

Executive summary:

In a primary dermal irritation study according to OECD 404, 3 young adult New Zealand White rabbits were dermally exposed to 0.5 g niobium pentoxide (99.99%) moistened with water ad injectionem for 4 hours under a 2-ply 25x25 mm gauze pad covered with “Electroplast” elastic adhesive. Animals then were observed after 24, 48 and 72 hours after patch removal. Irritation was scored according to OECD guideline 404. No irritation was observed.

In this study, niobium pentoxide is not a dermal irritant.

The information for niobium pentoxide is used in a read-across approach in the assessment of niobium 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:

2000-07-24 to 2001-06-21

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. Data are used in a read-across approach for the assessment of niobium carbide.

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Harlan UK Ltd., Bicester, Oxon, England
- Age at study initiation: 11 weeks
- Weight at study initiation: 2.3 to 3.0kg
- Housing: metal cages with perforated floors
- Diet (e.g. ad libitum): standard laboratory rabbit diet (Special Diet Services STANRAB (P) SQC pellet)
- Water (e.g. ad libitum):ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19+/-2
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

unchanged (no vehicle)

Controls:

other: untreated eyes of the animals served as control

Amount / concentration applied:

100 mg

Duration of treatment / exposure:

Single treatment

Observation period (in vivo):

72 h

Number of animals or in vitro replicates:

3

Details on study design:

Eyes were evaluated at 1, 24, 48 and 72 hours after instillation

Irritation parameter:

cornea opacity score

Remarks:

- Corneal opacity

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

iris score

Remarks:

- Iridal lesions

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

conjunctivae score

Remarks:

- Conjuctival redness

Basis:

mean

Remarks:

(mean of three animals and of three time points)

Time point:

24/48/72 h

Score:

0.3

Max. score:

2

Reversibility:

fully reversible

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritant / corrosive response data:

No corneal damage or iridial inflammation was observed.
Transient hyperaemia of the blood vessels to a diffuse crimson colouration of teh conjunctivae was seen in all animals with above normal swelling in two animals. All reactions had resolved completely by one, two, or three days after isntallation.

Rabbit no. & sex	Region of eye		1h	24h	48h	72h
1391 Male	Cornea	Density	0	0	0	0
		Area	0	0	0	0
	Iris		0	0	0	0
	Conjuctiva	Redness	2	1	0	0
		Chemosis	1	0	0	0
1460 Male	Cornea	Density	0	0	0	0
		Area	0	0	0	0
	Iris		0	0	0	0
	Conjuctiva	Redness	1	1	1	0
		Chemosis	1	0	0	0
1461 Male	Cornea	Density	0	0	0	0
		Area	0	0	0	0
	Iris		0	0	0	0
	Conjuctiva	Redness	1	0	0	0
		Chemosis	0	0	0	0

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In a primary eye irritation irritation study according to OECD Guideline 405 niobium pentoxide was tested as not irritating to the eye.

Executive summary:

In a primary eye irritation irritation study according to OECD Guideline 405, 100 mg niobium pentoxide (99.99%) was instilled to one eye of 3 male New Zealand White rabbits each (single instillation). Animals were observed 1, 24, 48 and 72 hours after instillation. Irritation was scored regarding corneal opacity, iridal lesions, conjunctival redness and chemosis. Except conjunctival redness all scores remained 0, giving no hint on eye irritation. 3 out of 3 animals showed conjunctival redness, which was fully reversible until 72 hours latest. Therefore, niobium pentoxide is not an eye irritant in this test.

The information is used in a read-across approach for the assessment of niobium carbide.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Niobium pentoxide is used to assess in a read-across approach the skin and eye irritating/corrosive potential of niobium carbide. Assuming that niobium is the crucial component of niobium carbide for the toxicity assessment, niobium pentoxide data serve the purpose of toxicity assessment as it is of similar solubility in water compared to niobium carbide. Thus, the applied doses of niobium by treatment with niobium pentoxide fulfil the requirements of test dosages specified in OECD guidelines 404 and 405. For further information please refer to the read-across report.

Niobium pentoxide did not reveal dermal irritation potential in an OECD 404 study conducted with three young adult New Zealand White rabbits. Single instillation of niobium pentoxide to one eye of three male New Zealand White rabbits each resulted in slight irritation regarding conjunctival redness (mean score 0.3; all other scores remained 0) which was fully reversible within 72 hours. Thus, niobium pentoxide is not considered to be an eye irritant.

Justification for selection of skin irritation / corrosion endpoint:

GLP Guideline study.

Justification for selection of eye irritation endpoint:

GLP Guideline study.

Justification for classification or non-classification

The read across partner niobium pentoxide 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 these results the target substance niobium carbide does not warrant classification for skin and eye irritation in accordance to CLP regulation (EC) No 1272/2008.