Identification of inorganic dust particles in bronchoalveolar lavage macrophages by energy dispersive x-ray microanalysis

This study shows that energy dispersive x-ray microprobe analysis to identify and quantify intracellular particles in macrophages obtained by the minimally invasive method of bronchoalveolar lavage (BAL) can detect inorganic dust exposures of many different kinds. Bronchoalveolar lavage macrophages from 22 patients have been examined. Twelve patients had occupational exposure to asbestos, talc, silica, hard metal or printing ink, while 10 had no known history of dust exposure. X-ray microprobe analysis identified particles which related to the known exposures, superimposed on a background of other particles related to smoking (kaolinite and mica) or to the general environment (silicon, titanium, and iron). The particle identification provided useful objective confirmation of the known exposures, except for silica, which could not be distinguished from the general background levels. X-ray microanalysis using BAL macrophages can be helpful for clarification of mixed dust exposures, to identify particles when light microscopy indicates retained dust in patients with no known history of exposure, and to monitor retained particles after removal from exposure.