Successful treatment of life-threatening propionitrile exposure with sodium nitrite/sodium thiosulfate followed by...

Propionitrile, a substituted aliphatic nitrile commonly used in the chemical manufacturing industry, is capable of generating cyanide. However, there are few reports of human intoxication involving propionitrile. We report two workers at an organic chemical manufacturing plant who were overcome by fumes while treating a waste slurry into which unreacted propionitrile was discharged by mistake. One victim was comatose, acidotic, and hypotensive; his blood cyanide level was later measured at 5.0 micrograms/ml. He responded to sodium nitrite/sodium thiosulfate therapy by regaining consciousness. Continued symptoms were treated with hyperbaric oxygen at 2 atmospheres for a total of 4 hours. The second victim, who complained only of nausea, dizziness, and headache and who never lost consciousness, was treated with sodium nitrite/sodium thiosulfate. His measured blood cyanide concentration was 3.5 micrograms/ml. The ambient concentration of propionitrile in air samples at the work site shortly after the exposure was 77.5 mg/m3. In occupational situations in which workers exhibit rapidly progressive symptoms of headache, dizziness, collapse, and coma, and where substituted nitriles are known to be on site, acute cyanide poisoning should be strongly considered. Because of continued endogenous generation of cyanide from the metabolism of the parent compound, hyperbaric oxygen may be a valuable adjunctive therapy to consider, in addition to the immediate use of the cyanide antidote kit, in cases of poisoning by propionitrile or other substituted nitrile compounds. We urge the Occupational Safety and Health Administration to adopt workplace standards for the maximum ambient air concentrations for propionitrile.