Smoking and the pulmonary mineral particle burden

The total pulmonary mineral particle burden and types of environmental particles were assessed in relation to smoking in 11 unselected autopsy lungs from adult male smokers and paired male non-smokers matched by age and lung. The lungs were fixed intrabronchially with formalin-polyethylene glycol-alcohol solution at a standard pressure and air-dried. A sample of 1-2 cm3 was taken from the posterior or apicoposterior segment of the right/left upper lobe and plasma ashed at low temperature. The mineral particles were identified by scanning transmission electron microscopy (STEM), electron microprobe analysis and electron diffraction. The number, mass and volume were calculated from the STEM image. The smokers' lung tissue had a lower number (54 +/- 15 X 10(6), mass (5.1 +/- 3.2 micrograms), volume (183 +/- 122 X 10(-5) mm3) and surface area (104 +/- 44 mm2/cm3 of lung tissue) of particles than the non-smokers' lung tissue (68 +/- 42 X 10(6), 12.6 +/- 13.4 micrograms, 468 +/- 501 X 10(-5) mm3 and 191 +/- 167 mm2/cm3 of lung tissue, respectively). All mineral types except talc were more numerous in the non-smokers' than in the smokers' lung tissue. The mineral particles were typical of the Finnish bedrock: quartz 15 +/- 7%, plagioclase 8 +/- 4%, microcline 13 +/- 5%, micas 22 +/- 10%, talc 4 +/- 4% and kaolinite 10 +/- 5%. Fibres were observed in only 2 cases, amounting to 1% in each. The lower mineral particle content of the smokers' lungs probably reflects more active clearance mechanisms caused by cigarette smoke.