Exposure to cobalt metal (without tungsten carbide) and some cobalt compounds: a literature review

Cobalt is a natural metallic element with extensive applications across multiple industries, and a critical metal for lithium-ion battery production. Cobalt's only known biological function is its role as a metal component of vitamin B12. Other cobalt compounds have been described as toxic to the environment and the human body following excessive exposure. The International Agency for Research on Cancer (IARC) has classified cobalt, including cobalt metal and soluble cobalt(II) salts, as Group 2A, meaning it is probably carcinogenic to humans. This review aims to present a comprehensive overview of historical and current sources of cobalt in diverse exposure settings, along with its various intake routes. An extensive literature search was conducted between September 2021 and January 2022, analysing over 300 publications. The primary goal of these studies was to identify cobalt sources, intake routes, and exposure pathways. Workers may be exposed to various cobalt compounds and metal powders primarily through inhalation, but exposure can also occur via skin contact or ingestion. For the general population, food typically arises as the predominant source of cobalt exposure. Furthermore, exposure may occur through ambient air, tobacco smoke, and medical implants.