Cyanide is one of the most potent, rapidly acting, poisons known. Cyanides inhibit the oxidative processes of cells causing them to die very quickly. Because the body rapidly detoxifies cyanide, an adult human can withstand 50-60 ppm for an hour without serious consequences. However, exposure to concentrations of 200-500 ppm for 30 minutes is usually fatal. 5Aside from death, acute cyanide toxicity at small doses can cause headache, tightness in throat and chest, and muscle weakness. The effects of chronic (long-term) exposure to cyanide are less well known