High Death Rate Seen After Nickel Carbonyl Exposure

NEW YORK (Reuters Health) - Patients who seek treatment during the delayed phase of nickel carbonyl exposure have a high rate of death, according to a new report. The findings suggest a need for trials of drugs that counteract the effects of nickel carbonyl in such patients, say the report's authors.

"Nickel carbonyl is formed when carbon monoxide comes into contact with active nickel," Dr. Raymond C. S. Seet, of National University Hospital, Singapore, and colleagues note. "The inhaled nickel carbonyl is rapidly absorbed and distributed mainly to the lungs, brain, adrenal glands, and kidneys," they add. "In severe cases, acute nickel carbonyl exposure has been reported to cause death."

In the current issue of the medical journal Chest, the researchers describe the clinical course, X-ray results, and autopsy findings of patients who developed nickel carbonyl poisoning after exposure at a waste management factory in Singapore.

Seven men were seen within 12 hours of each other with fever, chills, chest pain and shortness of breath. The subjects had worked a four-hour shift three days before their hospital admission. They underwent extensive microbiological and toxicological testing for known pathogens and occupational toxins.

Three of the seven men died. The results of microbiological investigations were unremarkable. All patients had elevated levels of nickel in their urine. The concentrations ranged from 19.8 to 78.5 mcg/L on days 8 to 15 after exposure. Normal concentrations are between 2 and 10 mcg/L.

None of the patients received treatment to counteract the poison.

Autopsies revealed hemorrhaging, fluid accumulation and fibrosis in the lungs.

Investigations at the factory suggested the use of an out-of-date chemical during neutralization of the nickel waste was the likely source of nickel carbonyl poisoning.

Slower distribution of nickel compounds into the body may explain the adverse outcomes in these patients who became ill three day after the initial nickel carbonyl exposure and may also account for the lung fibrosis found at autopsy and the lung damage that occurred before symptoms developed, they note.

Treatment with drugs, such as diethyldithiocarbamate or disulfiram, are under investigation for use in nickel carbonyl poisoning, the authors note. "Even though encouraging results have been reported in animal studies, information on (such treatment) in humans has been limited to case reports and series."

However, recovery can occur without treatment -- "four of our patients made complete recoveries despite severe respiratory failure," they note. Further studies are needed to clarify the role of treatment for nickel carbonyl poisoning, especially in those seen during the delayed phases of exposure, the researchers conclude.

SOURCE: Chest, July 2005.