What Is Cobalt?

IARC says cobalt is used in the manufacture of cutting and grinding tools, pigments and paints, colored glass, medical implants and electroplating, and increasingly in lithium-ion battery production. USGS estimates that 51% of the cobalt consumed in the United States was used in superalloys, mainly for aircraft gas turbine engines, 25% in chemical applications, 15% in other metallic applications and 9% in cemented carbides for cutting and wear-resistant uses. The NIH Office of Dietary Supplements says vitamin B12 contains the mineral cobalt, which is why compounds with vitamin B12 activity are collectively called cobalamins.

ATSDR says breathing cobalt particles can cause breathing difficulty and damage the nose, throat and lungs over time, that oral exposure to cobalt may cause adverse effects in the blood and thyroid, and that skin contact with cobalt particles may cause irritation and discoloration. A 2023 case report in the Journal of Medical Case Reports describes hard metal lung disease as a relatively less known but important cause of occupational interstitial lung disease, and says hard metals are composed of sintered tungsten carbide (80% to 90%) and cobalt (6% to 9%).

The FDA says that in metal-on-metal hip implants, the metal ball and metal cup slide against each other during walking or running, which can release tiny metal particles, and that some of the metal ions, such as cobalt and chromium, from the implant or the particles will enter the bloodstream. In 2022, an IARC Monographs Working Group classified cobalt metal and soluble cobalt(II) salts as probably carcinogenic to humans (Group 2A), based on sufficient evidence in experimental animals and strong mechanistic evidence in human primary cells, and classified cobalt(II) oxide as possibly carcinogenic to humans (Group 2B), based on sufficient evidence in experimental animals.