Cobalt

Cobalt has been used for centuries to make blue glass and pottery glazes — Cobalt Blue is the pigment — but its industrial importance exploded in the 20th century with its use in superalloys for jet engines, and more recently in lithium-ion battery cathodes [1]. Approximately 60% of global cobalt production comes from the Democratic Republic of Congo (DRC), where artisanal mining operations employ over 40,000 children in dangerous, unregulated conditions. The EV battery boom has dramatically increased cobalt demand and intensified supply chain scrutiny [2]. Hard metal disease — a severe progressive lung fibrosis — was first described among tungsten carbide workers in Belgium in the 1940s; cobalt metal dust is the causative agent when mixed with tungsten carbide in hard metal manufacturing. Metal-on-metal hip replacements, widely implanted in the 2000s, released cobalt and chromium ions that caused severe systemic cobalt toxicity in thousands of patients [3].

Occupational inhalation of cobalt dust and fumes is the primary route for hard metal workers, diamond polishing workers, and cobalt mining and processing workers [1]. Hard metal (WC-Co) workers in saw-making, dental drill manufacturing, and hard metal tool production have the highest occupational lung disease risks. Metal-on-metal hip implant patients release cobalt ions directly into their bloodstream — cobalt serum levels in some patients reached thousands of times normal, causing a syndrome of cardiomyopathy, neurological damage, hypothyroidism, and vision impairment [2]. Dietary cobalt intake from food (cobalt is an essential trace element as part of vitamin B12) is universally present but not a health concern at normal levels [3]. Lithium-ion battery manufacturing workers face cobalt dust exposure.

Cobalt compounds are classified as probable human carcinogens (IARC Group 2A), with evidence for lung cancer in hard metal workers [1]. The hard metal lung disease (cobalt-induced fibrosis/hypersensitivity pneumonitis) can progress to respiratory failure and death with continued exposure even after diagnosis. The metal-on-metal hip implant disaster revealed a toxicity pathway that was entirely unexpected: metal ions from implant surface wear triggered both local tissue destruction (pseudotumors, bone death) and systemic cobalt poisoning [2]. Systemic cobalt toxicity causes cardiomyopathy (heart failure), neurological damage including vision loss and hearing loss, hypothyroidism, and skin rashes — the same syndrome historically seen in cobalt-polluted beer ("Quebec beer drinkers' cardiomyopathy" in 1965) [3].

Hard metal workers, diamond polishers, and saw-manufacturing workers face occupational respiratory risks [1]. Patients with metal-on-metal hip or knee implants should have cobalt blood levels monitored annually — elevated levels (above 1 µg/L) warrant investigation and may require implant revision [2]. Workers in cobalt refining, battery manufacturing, and the DRC artisanal mining sector face the highest overall exposures.

If you have a metal-on-metal hip or knee implant, ask your orthopedic surgeon for annual metal ion blood tests (cobalt and chromium) — the FDA issued guidance recommending monitoring [1]. If your levels are elevated, consult an orthopedic surgeon specializing in implant revision about whether revision surgery is indicated [2]. Occupational hard metal workers should have annual chest X-rays, CT scans (for high-risk workers), and lung function testing. Use local exhaust ventilation and N95 or P100 respirators in cobalt dust environments. Report any unexplained shortness of breath, exercise intolerance, or chest symptoms promptly [3].