ABSTRACT
The first biological studies of nickel, conducted at the beginning of the nineteenth century, were concerned with its toxicity (1). In 1890, nickel carbonyl, a highly toxic nickel compound, was detected, and in 1912, nickel contact dermatitis in industrial workers was described for the first time. The first reports about carcinogenicity of nickel compounds were published in 1932 (1,2). By 1926 it was observed that nickel influences the metabolism of glucose, and in 1929 it was observed that nickel has a positive effect on anemia (3). Although these findings implied that nickel might be an essential element for animals, it was not until 1970 that the first possible signs of nickel deprivation were described (4). However, these first nickel deficiency signs, and others that were described shortly thereafter, were obtained under conditions that produced suboptimal growth in the experimental animals, and some signs of nickel deprivation appeared inconsistent (5). Since 1974, diets have been used which allowed production of nickel deficiency signs, and the essentiality of nickel has been confirmed in several studies in rats (6,7), chicks (8), pigs (9), goats (10), sheep (11), and cows (12). Although the biochemical functions of nickel in animals are not yet clear, today there is no doubt that nickel plays an important role in metabolism (3,5,13–15).
