SPECIATION OF AIRBORNE DUST FROM A NICKEL REFINERY ROASTING OPERATION

Earlier work-related lung and nasal cancer studies included estimates of exposures to different nickel species in the refinery. Based on the metallurgy, only insoluble nickel was believed to be present around t he roasters but mixed exposure was assumed in most areas, including th e tankhouse, Occasional leaching tests of samples from the roaster are a have indicated the presence of soluble nickel. This study reports on five parallel sets of dust samples collected from different floors wi th standard equipment and treated as follows. Two sets mere leached wi th an ammonium citrate buffer at pH 4.4. Undissolved material was trea ted with HClO4/HNO3, evaporated to dryness and dissolved in HCl. Ni, C u, Co, Fe, Se, and As were determined in both fractions. Water soluble Ni was found in all samples, ranging from 5-35%, Sulfate in the solut ions correlated nearly stoichiometrically to the total metal content. The three remaining sets mere investigated by, respectively, different ial leaching, X-ray diffraction and scanning electron microscopy. The percentage of soluble nickel found by differential leaching correspond ed well with those obtained by the simplified procedure. X-Ray diffrac tion analysis showed the presence of NiSO4 . 6H(2)O as well as oxides of Ni and Cu. This study indicates mixed exposures also in the roaster area. It also clearly indicates that basing exposure on the metallurg y alone can lead to serious misjudgements. The impact of this new info rmation on the interpretation of cancer incidence at this refinery mus t await the analysis in an ongoing case-reference study.