cyanides

Cyanides are a class of chemical compounds that contain the cyano group (−CN) or, in inorganic forms, the cyanide ion (CN−). They occur as volatile hydrogen cyanide (HCN) gas, as salts such as sodium cyanide (NaCN) and potassium cyanide (KCN), and as a broad range of organic nitriles in which the cyanide group is bonded to carbon. The chemistry and toxicity of cyanides vary with the structure and counterion, but their common feature is a strong reactivity with biological systems and a tendency to interfere with cellular processes.

Cyanides appear in industrial contexts and in the environment. Hydrogen cyanide and cyanide salts are used in various manufacturing processes and can be released during improper handling. Some plants produce cyanogenic glycosides that release hydrogen cyanide when damaged; examples include cassava and certain seeds such as bitter almonds. Human exposure most often occurs through industrial emissions, contaminated air or water, or ingestion of contaminated foods.

Industrial uses include gold mining via cyanidation, electroplating, and the synthesis of nitriles for polymers, pharmaceuticals, and agrochemicals. Organic nitriles serve as versatile precursors in chemical manufacturing. Hydrogen cyanide is also employed in fumigation and as an intermediate in chemical synthesis, although its use is tightly regulated due to safety concerns.

Toxicity and safety: cyanides inhibit cellular respiration by binding to cytochrome c oxidase in mitochondria, leading to tissue hypoxia and potentially rapid death at high exposures. Symptoms of acute exposure include headache, dizziness, confusion, seizures, and coma. Treatment relies on prompt decontamination and antidotal therapy, such as hydroxocobalamin, with additional regimens used in some settings. Environmental and occupational safety measures include spill containment, adequate ventilation, protective equipment, and proper wastewater treatment.