Reaction mass of ditungsten carbide and tungsten carbide

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

1998-02-24 to 1999-06-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

ell documented, scientifically sound study that was conducted accordiing to GLP and OECD guideline 402.

Justification for type of information:

1. HYPOTHESIS FOR THE CATEGORY APPROACH: The hypothesis is that properties are likely to be similar or follow a similar pattern because of the presence of a common metal ion, in this case tungstate.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES):
Source: Tungsten Carbide
Target: Fused tungsten carbide
3. CATEGORY APPROACH JUSTIFICATION: See Annex 3 in CSR
4. DATA MATRIX: See Annex 3 in CSR

Cross-reference

Reason / purpose for cross-reference:

read-across: supporting information

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 402 (Acute Dermal Toxicity)

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

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 carbide

Details on test material:

- Name of test material (as cited in study report): Tungsten Carbide Powder - Pure- Physical state: Grey powder- Analytical purity: >99.98%- Storage condition of test material: Room temperature

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan UK Ltd Bicester Oxon England
- Age at study initiation: 8-11 weeks
- Weight at study initiation: 208-255g
- Housing: Individually in metal cages with wire mesh floors
- Diet (e.g. ad libitum): ad lib - Special Diet Services RM1(E) SQC expanded pellet
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-22.5
- Humidity (%): 29-52%
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12 (0700 - 1900 hours)

IN-LIFE DATES: From: 1998-02-24 To: 1998-03-10

Administration / exposure

Type of coverage:

occlusive

Vehicle:

other: methylcellulose

Details on dermal exposure:

TEST SITE
- Area of exposure: Dorso-lumbar region
- % coverage: 10%
- Type of wrap if used: Porous gauze held in place with a non-irritating dressing covered with a waterproof dressing encircling trunk of animal.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Warm water (30 to 40 degrees C) to remove residual test substance. The treated area was blotted dry with absorbent paper.
- Time after start of exposure: 24 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2 mL/kg bodyweight
- Concentration (if solution): 100% w/v in 1% w/v aqueous methylcellulose
- Constant volume or concentration used: Yes

VEHICLE
- Amount(s) applied (volume or weight with unit): 1% w/v aqueous methylcellulose

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5 males and five females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Cages of rats were checked at least twice daily for any mortalities
- Necropsy of survivors performed: Yes
- Other examinations performed: Clinical signs, body weight

CLINICAL SIGNS:
Animals were observed soon after dosing and at frequent intervals for the remainder of Day 1. On subsequent days animals were observed once in the morning and again at the end of the experimental day (with the exception of Day 15 - morning only). The nature and severity of the clinical signs and time were recorded at each observation.

BODYWEIGHT:
The bodyweight of each rat was recorded on Days 1 (prior to dosing), 8 and 15. Individual weekly bodyweight changes and group mean bodyweights were calculated.

TERMINAL STUDIES:
-Macroscopic pathology- All animals were subjected to a macroscopic examination which consisted of opening the abdominal and thoracic cavities. The macroscopic appearance of all tissues was recorded and macroscopic abnormalities were preserved.

Statistics:

no data

Results and discussion

Effect levels

Effect levels 1

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Effect levels 2

Key result

Sex:

male/female

Dose descriptor:

other: NOEL

Effect level:

> 2 000 mg/kg bw

Mortality:

No deaths occurred.

Clinical signs:

other: No evidence of a systemic response in any animal throughout the study following a single dose application of Tungsten Carbide Powder - pure.

Gross pathology:

No macroscopic abnormalities were observed for animals killed at study termination on Day 15.

Other findings:

No dermal irritation was seen in any animal during the study.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The NOEL and acute lethal dose to rats of Tungsten Carbide Powder- Pure was demonstrated to be greater than 2000 mg/kg bodyweight.

Executive summary:

No acute dermal toxicity data of sufficient quality are available for fused tungsten carbide (target substance). However, acute dermal toxicity data are available for tungsten carbide (source substance), which will be used for read-across. Due to similar water solubility and lower toxicity for the target substance compared to the source substance, the resulting read-across from the source substance to the target substance is appropriate. In addition, read-across is appropriate because the classification and labelling is similar for the source substance than the target substance, the PBT/vPvB profile is the same, and the dose descriptors are, or are expected to be, lower for the source substance. For more details, refer to the read-across category approach included in the Category section of this IUCLID submission and/or as an Annex in the CSR.