Nickel: a review of its occupational and environmental toxicology

Nickel and nickel compounds belong to the classic noxious agents encountered in industry, but is also known to affect non-occupationally exposed individuals, especially those handling stainless-steel and nickel plated articles of everyday use. For plants and some vertebrates, specifically for mammals, nickel is indispensable as one of the essential trace elements. The most important health problems due to exposure to nickel and nickel compounds are allergic dermatitis (nickel itch) and increased incidence of cancers of the lungs and nasal mucosa encountered among the workers after a long-term over-exposure to nickel. In this respect the most hazardous nickel compounds appear to be nickel sulfide and nickel oxide. The monitoring of nickel exposure levels can be based on blood serum and urine analyses, but also on nickel determinations in hair which have proved promising even in groups of non-occupationally exposed individuals. Nickel carbonyl is the most toxic of all of the nickel compounds encountered, but because of its relatively short half-life it does not seem to represent any actual biohazard from the standpoint of environmental pollution. To prevent incidence of malignancies it is recommended to include in the routine plan of the preventive medical examinations also the cytologic analysis supplemented, in the case of cytologic positivity, with the bioptic examination for epithelial dysplasia. A systematic medical surveillance of workers with known long-term exposure to nickel is, of course, essential. At present, a major attention is centered on biochemical interactions of nickel with copper, cadmium, iron, iodine and particularly with manganese known to significantly reduce the experimental carcinogenicity of nickel and nickel compounds.