Verifying the composition of certain commercial nickel compounds

Forty commercial samples chosen from three families of nickel compounds were purchased and chemically analyzed. The selection included 21 basic nickel carbonates, 5 nickel sulfides, and 14 nickel oxides sold by 18 producers or distributors in eight countries. The analytical results were compared with the information provided on the container labels. A number of errors were found in the label information ranging from minor inconsistencies and incomplete information to actual misrepresentation of the product. For example, nickel(II) oxides containing only 1-2% Ni(III) are being offered for sale as "nickel(III) oxide, Ni(2)O(3)." Thus researchers should not accept at face value the chemical identity presented by producers or distributors in catalogs and on labels. Since significant variations in biological properties have been found within each of these three families of nickel compounds, researchers should carefully establish which particular member of a family is being studied. Unfortunately, the literature on the biological effects of nickel compounds contains numerous studies where this was not done. Attributing the results of such studies to other or, worse, to all members of the same family of nickel compounds may introduce significant errors into risk assessments.