CYANIDES - DANGER OF CYANIDES BASIC INFORMATION AND TUTORIALS

What are the dangers of cyanide?

As a group, the cyanides are among the most toxic and fast-acting poisons. (This is due to the cyanide ion which interferes with cellular oxidation.)

Hydrogen cyanide (prussic acid) is a liquid with a boiling point of 26°C. Its vapour is flammable and extremely toxic. This material is a basic building block for the manufacture of a range of chemical products such as sodium, iron or potassium cyanide, methyl methacrylate, adiponitrile, triazines, chelates.

Toxic effects of hydrogen cyanide 
Concentration in air Effect (ppm)
2–5 Odour detectable by trained individual
10 (UK MEL 10 mg/m3 STEL (SK))
18–36 Slight symptoms after several hours
45–54 Tolerated for 3–60 min without immediate or late effects
100 Toxic amount of vapours can be absorbed through skin
110–135 Fatal after 30–60 min, or dangerous to life
135 Fatal after 30 min
181 Fatal after 10 min
270 Immediately fatal

Although organocyanides (alkyl cyanides, nitriles or carbonitriles), in which the cyanide group is covalently bonded, tend as a class to be less toxic than hydrogen cyanide, many are toxic in their own right by inhalation, ingestion or skin absorption. Some generate hydrogen cyanide under certain conditions, e.g. on thermal degradation.

Depending upon scale of operation, precautions for cyanides include:
• techniques to contain substances and avoid dust formation (solid cyanides), aerosol formation (aqueous solutions), and leakages (gas);
• gloves, face and hand protection;
• high standards of personal hygiene;
• ventilation and respiratory protection (dust or gaseous forms);
• environmental monitoring for routine processes;
• health surveillance.