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Dust entry

Cemented tungsten carbide dust

Airborne particulate from cemented tungsten carbide and hard-metal processing.

Airborne form

dust

The form describes what is suspended in air at the point of exposure. A material can produce more than one form, such as dust during handling and fume during heating.

Health effects

eye irritationskin irritationrespiratory irritationskin sensitizationpulmonary fibrosiscoughnauseablood changes

Evidence

A NIOSH health-hazard evaluation of cemented tungsten-carbide workers identified hard-metal disease and possible occupational asthma among workers, and assessed relationships with cumulative cobalt exposure.

Source: pdf ↗ · saved source
page 1 · Executive Summary · 1
One former worker had findings of hard metal disease on chest x-rays, and two current workers had results indicating possible hard metal disease. One worker had occupational asthma. Workers with greater cobalt exposure over their work tenure were more likely to have abnormal lung function.

NIOSH lists inhalation, ingestion, skin, and eye contact routes for cemented tungsten carbide and reports eye, skin, and respiratory irritation, possible cobalt or nickel skin sensitization, diffuse pulmonary fibrosis, loss of appetite, nausea, cough, and blood changes; target organs include eyes, skin, respiratory system, and blood.

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Symptoms and target organs · 1
Exposure Routes: inhalation, ingestion, skin and/or eye contact. Symptoms: irritation eyes, skin, respiratory system; possible skin sensitization to cobalt, nickel; diffuse pulmonary fibrosis; loss of appetite, nausea, cough; blood changes. Target Organs: Eyes, skin, respiratory system, blood.

A NIOSH health-hazard evaluation of hard-metal grinding examined cobalt, chromium, and nickel exposure and reviewed possible health effects among workers performing grinding and welding tasks.

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page 1 · Description · 1
An investigation was begun into possible health effects from exposure to cobalt, chromium, and nickel in the Nozzle Shop area. The damaged vanes were removed from the nozzle frame by grinding off the connecting weld using hand held portable grinders.

NIOSH's cobalt criteria document reports ventilatory impairment and possible fibrosis or prefibrotic changes in hard-metal workers exposed to cobalt in cemented-carbide dust, including breathing-zone concentrations around 0.1–0.2 mg/m³ in the cited studies.

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page 51 · Health Effects · 2
The mean TWA concentration of cobalt in the breathing zones of seven individuals was 0.18 mg/cu m (range, 0.03-0.43); four concentrations exceeded 0.1 mg/cu m. These studies support a tentative conclusion that hard metal workers can develop fibrosis or prefibrotic changes when exposure to cobalt is in the range of 0.1-0.2 mg/cu m.

A NIOSH workplace evaluation collected personal air samples for cobalt, tungsten, and total and respirable dust; the report states that other contaminants, especially cobalt, had lower exposure limits than the nuisance-dust criteria used for comparison.

Source: pdf ↗ · saved source
page 2 · Summary · 1
Personal air samples for cobalt, tungsten (soluble and insoluble forms), and total and respirable dust were obtained ... Respirable dust exposures ranged from 0.04 to 0.72 mg/m3 ... other contaminants, with lower exposure limits (most notably cobalt), were identified in the dust samples.

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