Agent Name

Cobalt

CAS Number

7440-48-4

Formula

Co

Major Category

Metals

Synonyms

Cobalt metal dust; Cobalt metal fume; [NIOSH]

Category

Elements, Metallic

Description

Odorless, silver-gray to black solid; [NIOSH]

Sources/Uses

Occupational asthma reported in hard metal grinders and diamond polishers; [Malo] Allergic contact dermatitis in electronics workers; [Marks] Cobalt chloride skin allergy often accompanies chromium and nickel sensitization. Affected workers include electroplaters, hairdressers, cement handlers, and metal tool manufacturers and users. [Kanerva, p. 427] Also used in orthopedic prostheses, glass and paint pigments, and catalysts; it may be released in emissions from burning fossil fuels. Cobalt is an essential nutrient in the human diet in the form of Vitamin B12 (cyanocobalamin). Radioactive cobalt is used in medicine and food/equipment irradiation. [ATSDR ToxProfiles] In industry, mainly used to make alloys and hard metal (powder preparation, pressing, and shaping); Hard metals contain tungsten carbide (90%) and cobalt metal (10%); CoCrMo (Vittalium) is an alloy used in joint replacements; May be added to fertilizers for low-cobalt soils; [Nordberg, p. 511]

Comments

Cobalt is rapidly excreted in the urine; It may accumulate in the lung after inhalation of insoluble compounds; Goiter is a known side effect of cobalt treatment for anemia; Hard metal lung disease is caused by the composite material, a mixture of cobalt and tungsten carbide, that can injure the lung by producing 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. 511-25] Pulmonary edema can result from heavy exposure to cobalt fumes. [Harber, p. 496] A cross-sectional study of 82 workers in a cobalt refinery with an average exposure of 8 years found mild thyroid dysfunction (decreased T3, T4, and increased TSH). No evidence of pulmonary fibrosis was found in these workers exposed to cobalt alone (not to hard metal). [Reference #1] An epidemic of cardiomyopathy occurred in the 1960s among heavy drinkers of beer containing cobalt. A recent study of cobalt workers correlated cummulative cobalt exposure with echocardiographic changes but not with cardiac dysfunction. [Reference #2] Cobalt is a "hepatotoxic agent." [Zimmerman, p. 4] Can cause immunologic, occupational contact urticaria; [Kanerva 2004, p. 104] "Accordingly, a TLV–TWA of 0.02 mg/m3, as Co, is recommended to minimize the potential risk of developing asthma, pulmonary function changes, and myocardial effects. The recommended TLV applies to elemental cobalt and inorganic compounds, including cobalt exposure in the cemented tungsten carbide industry." [ACGIH] See "Cobalt-60" the most important radionuclide.

Reference Link

Epidemiological survey of workers exposed to cobal...[Br J Ind Med. 1993] - PubMed Result

Exposure Assessment
BEI

Cobalt in urine = 15 ug/L; cobalt in blood = 1 ug/L; sample at end of shift at end of workweek;

Skin Designation (ACGIH)

Insufficient data

Bioaccumulates

Yes

PEL (OSHA)

0.1 mg/m3, as Co (metal dust and fume)

Excerpts from Documentation for IDLHs

It has been reported that animals chronically exposed for 3 years to a cobalt-metal blend at a concentration of 20 mg Co/m3 developed fibrotic lesions in the lungs [Patty 1963].

Explanatory Notes

Cobalt with tungsten carbide is classified as 2A (probably carcinogenic to humans). [IARC]

Half Life

Whole body (depends on compound and route): 5 days to 4 years; [TDR, p. 379]

Reference Link

Exposure to cobalt in the production of cobalt and...[Occup Environ Med. 2004] - PubMed Result

Adverse Effects
Skin Sensitizer

Yes

Asthma

Yes

Toxic Pneumonitis

Yes

Fibrogenic

Yes

Hepatotoxin

Hepatotoxin, Secondary

IARC Carcinogen

Possible Carcinogen

ACGIH Carcinogen

Confirmed Animal

Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information

Chemical Information

Search ChemIDplus

Biomedical References

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Related Information in HazMap
Diseases

Occupational diseases associated with exposure to this agent:

Processes

Industrial Processes with risk of exposure:

Activities

Activities with risk of exposure: