Tungsten

Endpoint summary

Description of key information

In a skin irritation study conducted on rabbits according to OECD 404, tungsten metal was deemed to be not irritating. In an eye irritation study conducted on rabbits according to OECD 405, tungsten metal powder elicited transient very slight conjunctival irritation only.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1998-03-25 to 2000-01-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Well document study following OECD Guideline 404 performed under GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

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: 10-11 weeks
- Weight at study initiation: 2.3-2.6 kg
- Housing: stainless steel cages with perforated floors, Building R14, Room 4
- Diet: STANRAB (P) SQC , hay ad libitum
- Water: ad libitum
- Acclimation period: 6 days
- Female

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.5- 22.0
- Humidity (%): 38-62%
- Air changes (per hr): 19/hr
- Photoperiod (hrs dark / hrs light): 12/12

Type of coverage:

semiocclusive

Preparation of test site:

shaved

Vehicle:

other: distilled water

Controls:

not required

Amount / concentration applied:

500 mg applied, 0.5mL distilled water added to gauze pad

Duration of treatment / exposure:

4 hours

Observation period:

72 hrs: observations made at 60min, 24, 48 and 72 hours.

Number of animals:

3

Details on study design:

TEST SITE
- Area of exposure: 25mm x 25mm (6.25 cm^2)
- Type of wrap if used: moistened gauze covered with "Elastoplast"


REMOVAL OF TEST SUBSTANCE
-After four hours site was washed with warm water, blotted dry with absorbent paper


SCORING SYSTEM: Intact skin was evaluated for erythema and edema after 1, 24, 48 and 72 hours on a scale of 0-4 for each effect.

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

not specified

Remarks on result:

no indication of irritation

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

not specified

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

A single semi-occlusive application of Tungsten Metal Powder to intact rabbit skin for four hours elicited no dermal irritation over a 72-hour period.

Interpretation of results:

GHS criteria not met

Conclusions:

A single semi-occlusive application of Tungsten Metal Powder to intact rabbit skin for four hours elicited no dermal irritation over a 72-hour period.

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:

experimental study

Adequacy of study:

key study

Study period:

1998-03-30 to 2000-01-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Well documented study performed per OECD guideline and GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

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: 12 wks
- Weight at study initiation: 2.7 to 2.9 kg
- Housing: Individually in metal cages with perforated floors.
- Diet: ad lib. Special Diet Services STANRAB 9P0 SQC pellet
- Water: ad lib.
- Acclimation period: 18 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 22.5
- Humidity (%): 48 to 66
- Air changes (per hr): 19
- Photoperiod (hrs dark / hrs light):12/12


IN-LIFE DATES: From: 1998-03-30 To: 1998-04-04

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

100 mg was placed into the lower everted lid of one eye of each animal.

The guideline normally specifies a material volume (0.1mL) for instillation as long as the material weight does not exceed 100 mg. As the weight of 0.1 mL of tungsten exceeded 100 mg (523, 512, 608 mg on separate weighings) in accordance with the protocol a standard weight of 100 mg of the test substance was instilled.

Duration of treatment / exposure:

Single exposure.

Observation period (in vivo):

Examination of the eyes was made after 1 hr and 1, 2 and 3 days after instillation.

Number of animals or in vitro replicates:

3

Details on study design:

The eyes of each animal were examined prior to instillation of the test substance to ensure that there was no pre-existing corneal damage, iridial or conjunctival inflammation.
One animal was treated in advance of the others, to ensure that if a severe response was produced, no further animals would be exposed.

The eyelid was then gently held together for one second before releasing. The contralateral eye remained untreated.


OBSERVATIONS:
-Clinical Signs: All animals were observed daily for signs of ill health or toxicity.
-Ocular Response: Examination of the eyes was made after 1 hour and 1, 2, and 3 days after instillation (approximately 24, 48 and 72 hours).
SCORING SYSTEM: Ocular irritation was assessed using the prescribed numerical system with respect to the Cornea, Iris, Conjuctivae and Chemosis.

TOOL USED TO ASSESS SCORE: handheld light

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Remarks:

No corneal damage was observed.

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

2

Remarks on result:

no indication of irritation

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

3

Remarks on result:

no indication of irritation

Remarks:

conjunctival redness was observed in all 3 animals after 1 hour, but was not observed at subsequent time points

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

No corneal damage or iridial inflammation was observed.

Other effects:

Transient hyperaemia of the conjuctivae was seen in all 3 animals on Day 1, resolving completely by Day 2.

Interpretation of results:

GHS criteria not met

Conclusions:

Instillation of tungsten metal powder into the rabbit eye elicited transient very slight conjunctival irritation only.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Skin and eye irritation studies of sufficient quality and tested in accordance with standard methodology indicated that tungsten metal was not irritating to skin. The maximum eye irritation score reported was 1.0 for conjunctiva redness in all three animals at one hour; however, no effects were observed at 24, 48 or 72 hours. The mean score for all eye irritation endpoints as the average of 24, 48 and 72 hours was zero. Therefore, classification is not warranted for the skin and eye irritation endpoints.