Tungsten carbide

Eye irritation

Administrative data

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1998-03-02 to 1999-09-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Well documented, scientifically sound study that was conducted according to GLP and OECD Guideline 405 with no deviations.

Cross-reference

Reason / purpose for cross-reference:

assessment report

Reference

In a semi-occlusive skin irritation study conducted on rabbits according to OECD 404, tungsten carbide (WC) elicited no dermal irritation. In an eye irritation study conducted on rabbits according to OECD 405, instillation of WC into the rabbit elicited transient very slight to well-defined conjunctival irritation only. Based on the results of this study, WC can be considered as non-irritant.

Endpoint conclusion:

no adverse effect observed (not irritating)

Endpoint conclusion:

no adverse effect observed (not irritating)

Endpoint conclusion:

no study available

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Reference 2

Reference Type:

publication

Title:

SIDS Initial Assessment Report for SIAM 21 for Tungsten Carbide (12070-12-1), Washington DC,18-20 October, 2005

Author:

OECD-SIDS

Year:

2005

Bibliographic source:

UNEP Publications

Report date:

2005

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:

Tungsten carbide

EC Number:

235-123-0

EC Name:

Tungsten carbide

Cas Number:

12070-12-1

Molecular formula:

CW

IUPAC Name:

tungsten(4+) methanetetraide

Details on test material:

- Name of test material: Tungsten Carbide Powder - Pure
- Source: Supplied by the Sponsor
- Physical state: Grey powder
- Analytical purity: >99.98%
- Purity test date: January 27, 1998
- Stability under test conditions: Stable
- Storage condition of test material: Room temperature

Test animals / tissue source

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: 13 to 15 weeks
- Weight at study initiation: 3.1 to 3.5 kg
- Housing:Individually in metal cages with perforated floors.
- Diet (ad libitum): ad libitum STANRAB (P) SQC Rabbit Diet
- Water (eg ad libitum): ad libitium
- Acclimation period: Yes, but no time span given.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 22
- Humidity (%): 34 - 65%
- Air changes (per hr): 19
- Photoperiod (hrs dark / hrs light): 12/12 (0700 - 1900 hours)

IN-LIFE DATES: From: 1998-03-02 To: 1998-03-08

Test system

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): Weight of 0.1 mL test material (100 mg); 579, 526, 590. Mean weight of 0.1 mL test substance: 565 mg.

Duration of treatment / exposure:

A single instillation

Observation period (in vivo):

3 days

Number of animals or in vitro replicates:

3

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Not rinsed

SCORING SYSTEM: Ocular irritation was scored according to Draize.

TOOL USED TO ASSESS SCORE: handheld light

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

for all three animals

Time point:

24/48/72 h

Score:

0

Max. score:

8

Reversibility:

fully reversible

Remarks on result:

no indication of irritation

Results 2

Irritation parameter:

iris score

Basis:

mean

Remarks:

for all three animals

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

fully reversible

Remarks on result:

no indication of irritation

Remarks:

No iridial iritation or damage was observed throughout the study

Results 3

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

for all three animals

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

fully reversible

Remarks on result:

no indication of irritation

Results 4

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

3

Reversibility:

fully reversible

Remarks on result:

no indication of irritation

Results 5

Irritation parameter:

conjunctivae score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0.3

Max. score:

3

Reversibility:

fully reversible within: 2 days

Remarks on result:

probability of weak irritation

Remarks:

Redness

Results 6

Irritation parameter:

conjunctivae score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0.3

Max. score:

3

Reversibility:

fully reversible within: 2 days

Remarks on result:

probability of weak irritation

Remarks:

Redness

Irritant / corrosive response data:

- No corneal damage or iridial inflammation was observed.

Other effects:

- A diffuse crimson colouration of the conjuctivae with or without slight swelling (grade 1 or 2) was seen in two animals up to 24 hours; in the remaining rabbit chemosis grade 1 was observed only 1 hour after instillation; 48 hours after instillation all ocular reactions had resolved. Tungsten carbide
showed only a transient very slight to well-defined conjunctival irritation.
- Transient hyperaemia of blood vessels was observed in the remaining rabbit. These reactions had resolved by either one or two days after instillation.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Instillation of Tungsten Carbide Powder - Pure into the rabbit eye elicited transient very slight to well-defined conjunctival irritation only. Based on theresults of this study, tungsten carbide can be considered as non-irritant.