Kaolin pneumoconiosis. A case report.

A 35-year-old man who had been occupationally exposed to aerosolized kaolin for 17 years in a Georgia processing plant had diffuse reticulonodular pulmonary infiltrates and an upper lobe mass. Exploratory thoracotomy, performed to evaluate the nature of the mass, revealed an 8 X 12 X 10-cm conglomerate pneumoconiotic lesion containing large amounts of kaolinite. Coincident deposition of silica in the tissue was not demonstrable by either analytic scanning electron microscopy or x-ray diffraction. The case illustrates the effect of chronic kaolin exposure on the human lung and emphasizes the need for periodic evaluation of exposed workers.

Effectiveness of animal rotation in achieving uniform dust exposures and lung dust deposition in horizontal flow chambers.

An important source of variability of experimental results in inhalation toxicology originates from the nonuniformity of chamber concentrations. Two horizontal flow inhalation chambers were used in evaluating the effect of cage rotation within each chamber on the amount of alpha-quartz deposited in the lungs of male Fischer 344 rats. The alpha-quartz lung burden was determined by quantitative X-ray diffraction. A carefully designed animal rotation schedule significantly reduced the variability in the amount of alpha-quartz deposited in the animals, thereby minimizing effects of chamber nonuniformity due either to design or dust generator characteristics.

Mineral dusts as etiologic agents in pulmonary fibrosis: the diagnostic role of analytical scanning electron microscopy.

This report demonstrates the value of analytical scanning electron microscopy (SEM) in the evaluation of patients with fibrosing pulmonary disease. We describe the findings in six illustrative cases in which prebiopsy or premortem clinical and epidemiologic information did not suggest an etiologic association with exposure to fibrogenic dusts. Exogenous materials were inconstantly recognized by polarized light microscopy, but examination by SEM resulted in localization of significant inorganic deposits in the biopsy and autopsy tissues studied. Talc, mica, graphite, and mixed inorganic dusts were found in these six cases. Characterization of this material by SEM morphology and x-ray energy spectrometry provided the basis for re-appraisal of the exposure history and its potential pathogenetic importance. The technics described utilize routinely processed, paraffin-embedded tissue, and are readily applicable to problems encountered in the hospital setting.