Agent Name

Tungsten carbide (cemented)

Alternative Name

Hard metals containing Cobalt and Tungsten carbide

CAS Number

11107-01-0; 12718-69-3; 12070-12-1;

Major Category

Metals

Synonyms

Cemented tungsten carbide; Cemented WC; Hard metal; [NIOSH] Hard metals containing Cobalt [7440-48-4] and Tungsten carbide [12070-12-1], as Co; [ACGIH]

Category

Metals, Inorganic Compounds

Description

A mixture of tungsten carbide, cobalt, and sometimes other metals & metal oxides or carbides; [NIOSH]

Sources/Uses

Used to manufacture hard metal tools; [LaDou, p. 377] Occupational asthma reported in a metal grinder; [Malo] Used in construction, metalworking, mining, and oil/gas drillling industries; Workers exposed during tool grinding and sawblade sharpening/retipping; Exposure may occur during detonation gun welding; [ACGIH]

Comments

The tungsten carbide (WC) content is generally 85-95% and the cobalt content is generally 5-15%. [NIOSH] Hard metal lung disease is caused by the composite material, a mixture of cobalt and tungsten carbide; It is thought that inhaled cemented tungsten carbide injures the lung by releasing toxic oxygen species; Also may occur after exposure to cobalt metal powder mixed with iron and diamond dust in diamond polishers; There is no evidence that cobalt metal alone or other cobalt compounds can cause hard metal disease; [Nordberg, p. 753] "Sprince and colleagues (1984) reported that interstitial and obstructive lung disease was found in 11 of 290 subjects who worked at two tungsten carbide production plants.' [ACGIH] Skin sensitization to cobalt can occur in the hard metal industries. [Marks, p. 79] See "Tungsten." See "Cobalt."

Exposure Assessment
BEI

Cobalt in urine = nonquantitative; sample at end of shift at end of workweek;

Bioaccumulates

Yes

TLV (ACGIH)

0.005 mg/m3, as Co, thoracic particulate matter

Explanatory Notes

NIOSH REL = 0.05 mg/m3 (containing >2% Co) & 0.015 mg/m3 (containing >0.3% Ni); "This TLV does not apply to either tungsten carbide or cobalt exposures alone in the absence of the other material." [ACGIH] See TLVs for "Tungsten and compounds."

Adverse Effects
Skin Sensitizer

Yes

Asthma

Yes

Fibrogenic

Yes

ACGIH Carcinogen

Suspected Human

Links to Other NLM Databases
Toxicity Information

Search TOXNET

Chemical Information

Search ChemIDplus

Biomedical References

Search PubMed

Related Information in HazMap
Diseases

Occupational diseases associated with exposure to this agent:

Processes

Industrial Processes with risk of exposure: