occupational exposure to nickel compounds is dependent upon industrial processing and is usually substantially higher than work-unrelated nickel exposure. The form of nickel to which workers are exposed differs in the various industries in which nickel is used and occurs through inhalation or dermal contact (inhalation is the primary route of exposure), with ingestion taking place where there are poor industrial hygiene practices. It usually involves the inhalation of one of the following substances: dust of rela- tively insoluble nickel compounds, aerosols derived from nickel solutions (soluble nickel) and gaseous forms con- taining nickel (usually nickel carbonyl) . Many measurements conducted at various workplaces at risk (casting, welding, battery manufacture etc.) have revealed that the occupational concentrations may vary in a wide range from micrograms to milligrams of nickel per m3 of air. In nickel-producing or nickel-using industries, about 0.2% of the work force may be exposed to considerable amounts of airborne nickel, which may lead to the retention of 100 μg of nickel per day