Pulmonary Dust Retention in Silicotics with and without Lung Cancer

Abstract

Recent epidemiological studies suggest a possible increased risk of lung cancer in silicotic patients. To address the question of lung dust concentrations between silicotics with and without lung cancer, we used transmission electron microscopy and energy dispersive spectroscopy to analyze 41 lung tissue samples comprising 22 noncancer silicotics, 9 silicotics with lung cancer, and 10 accidental deaths without lung fibrosis at autopsy (referred to later as background group). Comparison between the background group and the pooled silicotic group revealed significantly higher lung dust concentrations and larger particle diameters of silica, feldspar, clay, mica, and total particles in the latter group (p < 0.05). When lung dust burdens of the noncancer silicotics and lung cancer silicotics were compared, the noncancer group had higher, but not significantly, geometric mean concentrations of total particles (16 × 10⁶ compared with 10 × 10⁶ particles/mg), silica (4 × 10⁶ compared with 2 × 10⁶), clay (4 × 10⁶ compared with 3 × 10⁶), feldspar (3 × 10⁶ compared with 2 × 10⁶), mica (0.6 × 10⁶) compared with 0.4 × 10⁶), iron (0.6 × 10⁶ compared with 0.3 × 10⁶), and metal-rich particles (0.7 × 10⁶ compared with 0.2 × 10⁶). Both groups had similar particle sizes and mineral compositions. In conclusion, the preliminary results confirm the presence of large quantities of dust of various sorts in silicotics. There were no statistically significant differences between the particle concentrations in the noncancer silicotic group and the lung cancer silicotic group, although the mean levels were higher in the noncancer group. Further investigation involving analysis of additional lung samples of each group, mineralogical characterization of silica particles by X-ray diffraction, and association between lung burden, dust exposure, and clinical findings is underway. Loosereewanich, P.; Ritchie, A.C.; Armstrong, B.; Begin, R.; Muir, D.C.F.; Dufresne, A.: Pulmonary Dust Retention in Silicotics With and Without Lung Cancer. Appl. Occup. Environ. Hyg. 10(12):1104–1106; 1995.