Cyanide poisoning

Cyanide poisoning occurs when a living organism is exposed to a compound that produces cyanide ions (CN−) when dissolved in water. Common poisonous cyanide compounds include hydrogen cyanide gas and the crystalline solids potassium cyanide and sodium cyanide. The cyanide ion halts cellular respiration by inhibiting an enzyme in the mitochondria called cytochrome c oxidase. Acute poisoning: Cyanide poisoning is a form of histotoxic hypoxia because the cells of an organism are unable to use oxygen, primarily through the inhibition of cytochrome c oxidase. Acute hydrogen cyanide poisoning can result from inhalation of fumes from burning polymer products that use Nitrile in their production, such as polyurethane, or vinyl. It can also be caused by break down of nitroprusside into nitric oxide and cyanide during treatment of hypertensive crises. If cyanide is inhaled it causes a coma with seizures, apnea, and cardiac arrest, with death following in a matter of seconds. At lower doses, loss of consciousness may be preceded by general weakness, giddiness, headaches, vertigo, confusion, and perceived difficulty in breathing. At the first stages of unconsciousness, breathing is often sufficient or even rapid, although the state of the victim progresses towards a deep coma, sometimes accompanied by pulmonary edema, and finally cardiac arrest. A cherry red skin color that changes to dark may be present as the result of increased venous hemoglobin oxygen saturation. Cyanide does not directly cause cyanosis. A fatal dose for humans can be as low as 1.5 mg/kg body weight. Chronic exposure: In addition to its uses as a pesticide and insecticide, cyanide is contained in tobacco smoke and smoke from building fires, and is present in some foods such as almonds, apricot kernel, apple seeds, orange seeds, cassava (also known as yuca or manioc), and bamboo shoots. Vitamin B12, in the form of hydroxocobalamin (also spelled hydroxycobalamin), may reduce the negative effects of chronic exposure, and a deficiency can lead to negative health effects following exposure. Exposure to lower levels of cyanide over a long period (e.g., after use of cassava roots as a primary food source in tropical Africa) results in increased blood cyanide levels, which can result in weakness and a variety of symptoms, including permanent paralysis, nervous lesions, hypothyroidism, and miscarriages. Other effects include mild liver and kidney damage.