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.

CARBON MONOXIDE DANGER AND EFFECTS BASIC INFORMATION AND TUTORIALS

What are the dangers of carbon monoxide?

Carbon monoxide
Carbon monoxide is a colourless, odourless gas and – without chemical analysis – its presence is undetectable. It is produced by steam reforming or incomplete combustion of carbonaceous fuels;

Carbon monoxide is extremely toxic by inhalation since it reduces the oxygen-carrying capacity of the blood. In sufficient concentration it will result in unconsciousness and death.

The STEL is 200 ppm but extended periods of exposure around this, particularly without interruption, raise concern for adverse health effects and should be avoided. If a potential carbon monoxide hazard is identified, or confirmed by atmospheric monitoring.

Typical carbon monoxide concentrations in gases

Gas Typical carbon monoxide concentration (%)
Blast furnace gas 20–25
Coal and coke oven gas 7–16
Natural gas, LPG (unburnt) nil
Petrol or LPG engine exhaust gas 1–10
Diesel engine exhaust gas 0.1–0.5

Typical reactions of persons to carbon monoxide in air

Carbon monoxide (ppm) Effect
30 Recommended exposure limit (8 hr time-weighted average concentration)
200 Headache after about 7 hr if resting or after 2 hr exertion
400 Headache with discomfort with possibility of collapse after 2 hr at rest or 45 min exertion
1200 Palpitation after 30 min at rest or 10 min exertion
2000 Unconscious after 30 min at rest or 10 min exertion