Tungsten carbide

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

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:

Well documented, scientifically sound study that followed OECD Guideline 401 and GLP.

Cross-reference

Reason / purpose for cross-reference:

assessment report

Reference

Acute toxicity studies of sufficient quality and tested in accordance with standard methodology on tungsten carbide indicate a low potential for acute toxicity when administered through oral, inhalation, or dermal routes. No histopathological effects were reported, and the LD50s/LC50s and NOELs reported in each study were greater than the highest dose tested, > 2000 mg/kg bw, > 5.3 mg/L/4hrs, and > 2000 mg/kg bw for the oral, inhalation, and dermal routes of administration, respectively.

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

Study conducted under OECD guidlines and under GLP

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

5 300 mg/m³ air

Quality of whole database:

Study conducted under OECD guidlines and under GLP

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

Study conducted under OECD guidelines and under GLP

Acute toxicity studies of sufficient quality and tested in accordance with standard methodology showed that the acute oral LD50 was greater than 2000 mg/kg in rats, the acute inhalation LC50 was greater than 5.3 mg/L/4hr in rats, and the acute dermal LD50 was greater than 2000 mg/kg in rats for tungsten carbide. The cutoff LD50 or LC50 values for classification are 2000 mg/kg for oral and dermal routes, and 5.0 mg/L/4hr for inhalation route. Therefore, no classification is required for the acute oral, dermal and inhalation toxicity for tungsten carbide.

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 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

The lowest humidity recorded was 29%. This was lower than the range of 30 - 70% stated in the protocol. This deviation was not considered to have affected the integrity or validity of the study.

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(4+) methanetetraide

Details on test material:

- Test substance: tungsten carbide, WC HC 240
- Purity: 99.98%
- Physical state: Grey powder
- Storage condition of test material: Room temperature
- Expiration date of the lot/batch: Not advised

Test animals

Species:

rat

Strain:

other: Hsd: Sprague-Dawley(CD))

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Obtained from Harlan U.K. Ltd, Bicester, Oxon, England.
- Age at study initiation: four to seven weeks or age.
- Weight at study initiation: range of 80 to 101 g.
- Fasting period before study: Access to food only was prevented overnight prior to and for approximately 4 hours after dosing.
- Housing: Rats were allocated without conscious bias to cages within the treatment group and housed in groups of five rats of the same sex in metal cages with wire mesh floors.
- Diet (eg ad libitum): A standard laboratory rodent diet (Special Diet Services RM1(E) SQC expanded pellet)
- Water: drinking water provided ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature: 21 to 22.5 °C
- Humidity: 9-52%
- Air changes: Air exchange was maintained at 10 to 15 air changes per hour.
- Photoperiod: lighting controlled by means of a time switch to provide 12 hours of artificial light (0700 - 1900 hours).


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

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 1 % w/v aqueous methylcellulose

Details on oral exposure:

The test substance was formulated at a concentration of 20 % (w/v) in 1 % (w/v) aqueous methylcellulos which was administered at a volume of 10 mL/kg-bw.

Doses:

single oral gavage dose of 2000 mg/kg bw

No. of animals per sex per dose:

5 male and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days

Statistics:

no data

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Effect levels 2

Sex:

male/female

Dose descriptor:

other: NOEL

Effect level:

> 2 000 mg/kg bw

Mortality:

0/5 for males and females

Clinical signs:

other: other: Piloerection was observed in all rats within three minutes of dosing. This sign persisted and was accompanied on Day 2 only by ungroomed appearance (characterised by ungroomed coat) in all males. There were no other signs of reaction to treatment a

Gross pathology:

No macroscopic abnormalities at terminal kill on day 15 were observed.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

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