The acute toxicity of nickel carbonyl by inhalation is high. Acute toxic effects occur
in two stages, immediate and delayed. Headache, dizziness, shortness of breath,
vomiting, and nausea are the initial symptoms of overexposure; the delayed effects
(10 to 36 h) consist of chest pain, coughing, shortness of breath, bluish discoloration
of the skin, and in severe cases, delirium, convulsions, and death. Recovery is
protracted and characterized by fatigue on slight exertion. Nickel carbonyl is not
regarded as having adequate warning properties.
Repeated or prolonged exposure to nickel carbonyl has been associated with an
increased incidence of cancer of the lungs and sinuses. Nickel carbonyl is listed by
IARC in Group 2B ("possible human carcinogen"), is listed by NTP as "reasonably
anticipated to be a carcinogen," and is classified as a "select carcinogen'' under the
criteria of the OSHA Laboratory Standard.