Nickel Tetracarbonyl - Toxicology and Safety Considerations

Toxicology and Safety Considerations

Ni(CO)₄ is highly hazardous, much more so than implied by its CO content, reflecting the effects of the nickel if released in the body. Nickel carbonyl may be fatal if absorbed through the skin or more likely, inhaled due to its high volatility. Its LC₅₀ for a 30-minute exposure has been estimated at 3 ppm, and the concentration that is immediately fatal to humans would be 30 ppm. Some subjects exposed to puffs up to 5 ppm described the odour as musty or sooty, but because the compound is so exceedingly toxic, its smell provides no reliable warning against a potentially fatal exposure. Historically, laboratories that used Ni(CO)₄ would keep a canary in the lab as an indicator of nickel carbonyl toxicity, due to the higher sensitivity of birds to this poison.

Human systemic effects by inhalation: somnolence, fever, and other pulmonary changes. Vapors may cause coughing, dyspnea (difficult breathing), irritation, congestion and edema of the lungs, tachycardia (rapid pulse), cyanosis, headache, dizziness, and weakness. Toxicity by inhalation is believed to be caused by both the nickel and carbon monoxide liberated in the lungs. Chronic exposure may cause cancer of lungs or nasal sinuses. Sensitization dermatitis is fairly common. It is considered the most hazardous compound of nickel in the workplace. It is lipid soluble and can cross biological membranes (e.g., lung alveolus, blood–brain barrier, placental barrier).

The vapours of Ni(CO)₄ can autoignite.

Nickel carbonyl poisoning is characterized by a two-stage illness. The first consists of headaches and chest pain lasting a few hours, usually followed by a short remission. The second phase is a chemical pneumonitis which starts after typically 16 hours with symptoms of cough, breathlessness and extreme fatigue. These reach greatest severity after four days, possibly resulting in death from cardiorespiratory or renal failure. Convalescence is often extremely protracted, often complicated by exhaustion, depression and dyspnea on exertion. Permanent respiratory damage is unusual. The carcinogenicity of Ni(CO)₄ is a matter of debate.

Nickel carbonyl vapor decomposes quickly in air, lasting only about a minute.