May 5, 2022

IARC Evaluates Carcinogenicity of Agents Including Cobalt, Antimony

The International Agency for Research on Cancer (IARC) recently completed its evaluation of the carcinogenicity of cobalt, antimony compounds, and weapons-grade tungsten alloy. The agency examined nine agents: cobalt metal (without tungsten carbide or other metal alloys), soluble cobalt(II) salts, cobalt(II) oxide, cobalt(II,III) oxide, cobalt(II) sulfide, other cobalt(II) compounds, trivalent antimony, pentavalent antimony, and weapons-grade tungsten (with nickel and cobalt) alloy. IARC classified three of the agents—cobalt metal, soluble cobalt(II) salts, and trivalent antimony—in Group 2A, the agency’s designation for agents that are probable carcinogens to humans. Two others—cobalt(II) oxide and weapons-grade tungsten alloy—fall into Group 2B and are possibly carcinogenic to humans, according to IARC. The agency found the remaining four agents to be not classifiable as to their carcinogenicity to humans.

IARC explains that antimony is used in products such as flame retardants, plastics, brake pads, and glass and ceramics, while cobalt is used to make cutting and grinding tools as well as in the manufacture of pigments and paints, colored glass, medical implants, and electroplating. Cobalt’s use in lithium-ion battery production is increasing, the agency says. Weapons-grade tungsten alloys are found in armor-penetrating munitions, and IARC notes that both military personnel and civilians can be exposed to metal aerosols generated during firing or impact. The agency stresses that “exposures are expected to be higher in occupational situations than in the general population” for all nine agents it evaluated.

A summary of IARC’s evaluation is available online in The Lancet Oncology. The full article is available free of charge to registered users (registration is also free). Further details can be found on IARC’s website.

IARC’s detailed assessments will be published later in Volume 131 of the IARC Monographs. IARC monographs identify and evaluate environmental factors that can increase carcinogenic hazards to humans. IARC is the specialized cancer agency of the World Health Organization, and agencies worldwide use its monographs as scientific support for their actions to prevent exposure to potential carcinogens.