Cobalt, Antimony Compounds, and Weapons-grade Tungsten Alloy - Volume 131 - IARC Monographs on the Identification of Carcinogenic Hazards to Humans

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This volume of the IARC Monographs provides evaluations of the carcinogenicity of 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.

Cobalt is used in the manufacture of cutting and grinding tools, in pigments, paints, coloured glass, medical implants, and electroplating, and in lithium-ion battery production. Occupational exposure is expected to occur predominantly during cobalt refining and production of cobalt compounds and dental materials; use of diamond–cobalt tools, plate painting with cobalt pigments, manufacture of nickel–hydrogen batteries, hard-metal production, and electronic-waste recycling. The general population is exposed via food, ambient air, tobacco smoke, and medical implants.

Antimony is used in flame retardants, lead–acid batteries, lead alloys, plastics, brake pads, clutch discs, glass and ceramics, and as a primer in explosives. Some pentavalent antimony compounds are used to treat leishmaniasis. Workers can be exposed during smelting, production of antimony compounds, manufacture of glass, textiles, and batteries, and electrical-waste processing. Non-occupational exposures occur via water, air, soil, consumer products, and tobacco.

Weapons-grade tungsten (with nickel and cobalt) alloy is used in armour-penetrating munitions. Occupational exposure can occur during munitions production, and military personnel and civilians can be exposed to metal aerosols generated during firing or impact, or via injuries with retained embedded fragments.

An IARC Monographs Working Group reviewed evidence from cancer studies in humans (available mainly for cobalt and antimony), cancer bioassays in experimental animals, and mechanistic studies to assess the carcinogenic hazard to humans of exposure to these agents and concluded that:

• Cobalt metal (without tungsten carbide or other metal alloys), soluble cobalt(II) salts, and trivalent antimony are probably carcinogenic to humans (Group 2A);
• Cobalt(II) oxide and weapons-grade tungsten (with nickel and cobalt) alloy are possibly carcinogenic to humans (Group 2B);
• Cobalt(II,III) oxide, cobalt(II) sulfide, other cobalt(II) compounds, and pentavalent antimony were each evaluated as not classifiable as to its carcinogenicity to humans (Group 3).