The nickel oxide chemical formula is NiO. This compound is a green or gray solid that does not dissolve in water. It is made by the action of nickel and oxygen at a temperature greater than 400degC or by pyrolysis of nickel carbonate at 350degC. It is used to make alloys, batteries, glass, enamel, ceramics, electronic components, and nickel salts.
The most common type of nickel toxicity is respiratory inhalation of nickel vapors & dusts of nickel oxide, nickel carbonyl & nickel chloride. Respiratory absorption can be influenced by: * the amount of nickel inhaled; & * the aqueous solubility & sorptivity of nickel vapors & dusts (following the general relationships of nickel carbonyl> soluble nickel cmpd> insoluble nickel cmpd).
A study of male Wistar rats was conducted to determine the pulmonary toxicity of inhaling nickel oxide aerosols. The rats were exposed to the vapors for 7 hr/day, 5 days/week, for less than or equal to 12 mo. After this period of time, they were sacrificed.
During a 10-day exposure, the nickel concn in the lung of the exposed rats was significantly higher than that in controls. However, this increase was not significant enough to cause any carcinogenic activity.
After a 3-mo exposure, the avg wt gain of the exposed rats was similar to that of controls. The avg nickel concn in liver, kidney, spleen, and blood was not significantly different between the exposure groups and controls.
After a 12-mo exposure, the avg concn in the lungs of exposed rats was slightly higher than that of controls. These changes were accompanied by increased alveolar macrophages. A small fraction of exposed rats had tumors, but these were not carcinogenic.
