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.