Hydrogen cyanide acute lethal inhalation toxicity

The acute toxicity of hydrazoic acid through inhalation and other routes of exposure has been found to be high to very high. The symptoms and the intensity of poisoning are similar to sodium azide. It is, however, less toxic than hydrogen cyanide. In humans, inhalation of its vapors can produce irritation of eyes and respiratory tract, bronchitis, headache, dizziness, weakness, and decreased blood pressure (Matheson 1983). Prolonged exposure to high concentrations can result in collapse, convulsion, and death. An exposure to 1100 ppm for 1 hour was lethal to rats. Chronic exposure to a low level of this compound in air may produce hypotension. 

Hydrogen cyanide is extremely toxic hy ingestion, inhalation, skin absorption, and all routes of exposure. An oral dose of 50 mg could be lethal to humans (Patnaik, P. 1999. A Comprehensive Guide to the Hazardous Properties of Chemical Substances, 2nd ed.. New York John Wiley). Symptoms from acute poisoning include labored breathing, shortness of breath, paralysis, unconsciousness, and respiratory failure. Lower doses can cause headache, nausea and vomiting. Oral LDsoin mice is 3.7 mg/kg. Amyl nitrite is an effective antidote. 

Hydrogen cyanide is a dangerous acute poison by all toxic routes. Acute inhalation may cause death in seconds. Lethal effects due to inhalation of its vapor depend on its concentration in air and time of exposure. Inhalation of 270 ppm HCN in air can be fatal to humans instantly, while 135 ppm can cause death after 30 minutes (Patty 1963 ACGIH... 

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