Reply #2: No, it was methyl isocyanate. [View All]

[seriousstan]

Methyl isocyanate (MIC) is extremely toxic. The threshold limit value set by the American Conference on Government Industrial Hygienist was 0.02 ppm which is an extremely low concentration. MIC can damage by inhalation, ingestion and contact in quantities as low as 0.4 ppm. Damage includes coughing, chest pain, dyspnea, asthma, irritation of the eyes, nose and throat as well as skin damage. Higher levels of exposure, over 21 ppm, can result in pulmonary or lung edema, emphysema and hemorrhages, bronchial pneumonia and death. Although the detectable odor of methyl isocyanate is a concentration triple the permissible exposure, its potent lachrymal properties provide an excellent warning of its presence (at a concentration of 2-4 parts per million (ppm) subject's eyes are irritated, while at 21 ppm subjects could not tolerate the presence of methyl isocyanate in air)(Kimmerle and Eben 1964).

Proper care must be taken to store methyl isocyanate because of its ease of exothermically polymerizing (see Reactions) and its similar sensitivity to water. Only stainless steel or glass containers may be safely used; the MIC must be stored at temperatures below 40ºC.

The toxic effect of the compound was apparent in the Bhopal accident, when around 43,000 kilograms of methyl isocyanate and other gases were released over a populated area on December 3, 1984, killing thousands of people.