ABSTRACT
Cobalt is a trace element, widely distributed in the environment, which has been in human use for centuries. Its unique qualities have led to increasing use in several applications and industries. Its characteristic blue color led to its use as a coloring agent in porcelain production, and its hardness and excellent wear qualities as alloy have been extensively used in the heavy metal industry and orthopedic implants. In humans, it plays a vital role as a component of cyanocobalamin (vitamin B12), contributing toward specific biochemical processes such as gene expression regulation, immune system, and antioxidant defense of the body. Excessive exposure of cobalt to humans (environmental, occupational, or medical) may lead to toxicity. This toxicity may present with symptoms related to the system it affects. Cardiac toxicity has been extensively studied in Quebec beer drinkers, and more recently in patients with metal-on-metal (MoM) hip implants. Respiratory toxicity is commonly seen in an occupational exposure and may present as asthma, alveolitis, or pulmonary fibrosis. Occupational exposure, particularly in the construction industry, may present as contact dermatitis. It may affect other systems as well, including neurology, psychiatric, and endocrine. Some concerns have been raised about the carcinogenic potential of excessive cobalt exposure, but there is no conclusive human study confirming it. However, radioactive exposure to cobalt in patients receiving radiotherapy, or workers of nuclear facilities and nuclear waste storage sites has shown to cause significant hazards including nervous tissue damage, visual disturbances, and dermatological effects.
