Tantalum carbide

Endpoint summary

Description of key information

Tantalum and tantalum pentoxide were tested for skin irritation/corrosion and eye irritation under GLP according to the OECD guidelines 404 and 405, respectively. Both tested substances revealed no irritating or corrosive potential to skin and eye.

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:

2000-09-23 to 2000-12-18

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. Tantalum used as read-across partner for Tantalum carbide.

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2500 (Acute Dermal Irritation)

Deviations:

no

GLP compliance:

yes

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: 2.5 - 2.6 kg
- Housing: individually in stainless steel cages with perforated floors
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 12 days

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

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

unchanged (no vehicle)

Remarks:

test material moistened with distilled water

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied: 0.5 g

Duration of treatment / exposure:

4 hours

Observation period:

72 hours

Number of animals:

3

Details on study design:

TEST SITE
- 24 hours prior to application of the test material, hair was removed with electric clippers from the dorso-lumbar region of each rabbit exposing an area of skin approximately 100 mm x 100 mm.
Approximately 0.5 g test material was applied under a 2-ply 25 mm x 25 mm porous gauze pad, which had been moistened with 0.5 mL distilled water, to one intact skin site on each animal. Each treatment site was covered with "Elastoplast" elastic adhesive dressing for 4 hours. The animals were not restrained during the exposure period and were returned to their cages immediately after treatment.

REMOVAL OF TEST SUBSTANCE
- Washing: 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 material. The treated area was blotted dry with absorbent paper.

CLINICAL SIGNS:
- All animals were observed daily for signs of ill health or toxicity

DERMAL RESPONSES:
- Examination of the treated skin was made on day 1 (approximately 60 minutes after removal of the dressings) and on days 2, 3 and 4 (equivalent to approximately 24, 48 and 72 hours after exposure).

SCORING SYSTEM: see field "Any other information on materials and methods incl. tables" for further information.

Irritation parameter:

erythema score

Basis:

mean

Remarks:

of three animals

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

0

Remarks on result:

other: no dermal irritation at all was observed

Irritation parameter:

edema score

Basis:

mean

Remarks:

of three animals

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

0

Remarks on result:

other: no dermal irritation was observed

Irritant / corrosive response data:

There were no signs of toxicity or ill health in any rabbit during the observation period and no dermal irritation was observed at any time during the test.

Other effects:

N.A.

Table 1: Dermal reactions
Rabbit no. & sex	E= Erythema O= Oedema		Day
			1*	2	3	4
1369 male	E		0	0	0	0
	O		0	0	0	0
1370 male	E		0	0	0	0
	O		0	0	0	0
1371 male	E		0	0	0	0
	O		0	0	0	0

* 60 minutes after removal of the dressing

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In conclusions, in an acute dermal irritation/corrosion study according to OECD 404, the test item tantalum was found to be non-irritating.

Executive summary:

In a primary dermal irritation study (OECD 404), three male New Zealand white rabbits were exposed to 0.5 g of tantalum (99.9 %) for 4 hours to a body surface area of 2.5 cm² under semi-occlusive conditions. Signs of erythema and oedema were recorded at 1, 24, 48 and 72 hours after removal of the dressing . Tantalum did not cause any skin effects and is not considered under the conditions of the test as dermal irritant.

These tantalum data are used in a read-across approach to describe the skin irritation potential of tantalum 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:

2000-10-03 to 2000-12-18

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. Tantalum used as read-across partner to Tantalum carbide

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2400 (Acute Eye Irritation)

Deviations:

no

GLP compliance:

yes

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: at least 12 weeks
- Weight at study initiation: 2.4 - 2.8 kg
- Housing: individually in stainless steel cages with perforated floors
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days

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

Vehicle:

unchanged (no vehicle)

Controls:

other: the contralateral eye of each treated animal remained untreated

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 100 mg

TREATMENT PROCEDURE
- The weight of the test material which when gently compacted occupied a volume of 0.1 mL exceeded 100 mg on all occasions. However, 100 mg only was placed in the lower everted lid of one eye of each animal. The eyelids were gently held together for one second before releasing. The contralateral eye remained untreated and served as a control.

Duration of treatment / exposure:

The treated eyes were not washed following test material installation.

Observation period (in vivo):

1, 24, 48 and 72 hours after installation

Number of animals or in vitro replicates:

3 males

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): not informed

SCORING SYSTEM: The reactions were scored in accordance with the numerical system outline in field "Any other information on materials and methods incl. tables".

TOOL USED TO ASSESS SCORE: Observation of the eyes was aided by the use of a handheld light.

OTHER: one animal was treated in advance of the other two, to ensure that if a severe response was produced, no further animals would be exposed

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

of three animals

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

0

Remarks on result:

other: No corneal damage was observed

Irritation parameter:

iris score

Basis:

mean

Remarks:

of three animals

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

0

Remarks on result:

other: No lesions were observed

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

mean

Remarks:

of three animals

Time point:

other: 24, 48 and 72 hours

Score:

0.1

Max. score:

0.3

Reversibility:

fully reversible within: 2 days

Remarks on result:

other: Redness was seen in the eye of one male rabbit after 24 hours

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

of three animals

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

0

Remarks on result:

other: No chemosis was observed

Irritant / corrosive response data:

No corneal damage or iridial inflammation was observed. Transient, hyperaemia of the blood vessels of the conjunctivae was seen in all animals, resolving completely by either one or two days after instillation.

Other effects:

There were no signs of toxicity or ill health in any rabbit during the observation period.

Table 1: Ocular reactions
Rabbit no. & sex	Region of eye		hours after instillation
			1	24	48	72
1389 male*	Cornea	Density	0	0	0	0
		Area	0	0	0	0
	Iris		0	0	0	0
	Conjunctiva	Redness	1	0	0	0
		Chemosis	0	0	0	0
1456 male	Cornea	Density	0	0	0	0
		Area	0	0	0	0
	Iris		0	0	0	0
	Conjunctiva	Redness	1	1	0	0
		Chemosis	0	0	0	0
1457 male	Cornea	Density	0	0	0	0
		Area	0	0	0	0
	Iris		0	0	0	0
	Conjunctiva	Redness	1	0	0	0
		Chemosis	0	0	0	0

* Pilot animal

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In conclusions, in this acute eye irritation/corrosion study according to OECD 405, the test item tantalum is considered to be non-irritating.

Executive summary:

In a primary eye irritation study (OECD 405), 100 mg of tantalum (99.9%) was placed in the lower everted lid of one eye of each of three young adult New Zealand White rabbits (males). Animals were observed for 72 hours. Irritation was scored by the method of Draize. Only a very mild conjunctival reaction was observed, which was fully reversible within 1-2 days. Based on the results obtained from this study, tantalum is considered to be not an eye-irritant.

These tantalum data are used in a read-across approach for the assessment of the skin irritation potential of tantalum carbide.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Tantalum and tantalum pentoxide were used to assess in a read across approach the skin and eye irritating/corrosive potential of tantalum carbide. Assuming that tantalum is the crucial component of tantalum carbide for the toxicity assessment, both tantalum and tantalum pentoxide serve the purpose of toxicity assessment as they are of higher solubility in water than tantalum carbide, with tantalum being slightly more soluble than tantalum pentoxide. Therefore the applied doses of tantalum by treatment with either tantalum of tantalum pentoxide fulfil the requirements of test dosages specified in OECD guidelines 404 and 405.

Tantalum and tantalum pentoxide showed no signs of toxicity or dermal reactions upon administration of 0.5 g onto the skin of rabbits for 4 hours.

Tantalum and tantalum pentoxide showed no signs of toxicity upon one-time instillation of 100 mg into the eye of the rabbit. Tantalum pentoxide and tantalum caused a very mild transient hyperaemia of the blood vessels of the conjunctivae in 2 of 3 rabbits and 3 of 3 rabbits, respectively, within one hour of substance instillation (100 mg each). These reactions were fully reversible within 1 day after instillation.

In summary, tantalum and tantalum pentoxide showed no irritative or corrosive potential to the skin and eye.

Justification for selection of skin irritation / corrosion endpoint:
GLP guideline study according to OECD 404

Justification for selection of eye irritation endpoint:
GLP guideline study according to OECD 405

Justification for classification or non-classification

No classification for tantalum carbide is required due to the non-toxicity of the two read-across partner substances tantalum and tantalum pentoxide.