The debate continues over cigarette smoking as a cause of radiographic opacities consistent with pneumoconiosis. We have recently reviewed this issue as part of a symposium on radiographic controversies in inorganic dust disease [Blanc and Gamsu, 19881. Our goal was to review published studies and to provide an analysis that could also be applied to future studies. Contemporaneous to our review, another evaluation of the effects of smoking on radiographic opacities appeared, once again demonstrating the need for critical analysis of this complicated issue [Weiss, 19881. The factions in this controversy are aligned into two opposing camps. One group holds that cigarette smoking alone causes radiographic opacities indistinguishable from those caused by inorganic dust inhalation [Weiss, 1984; Morgan, 19851. A second group accepts an association between cigarette smoking and dust inhalation on radiographic abnormalities but not that cigarette smoking is independently capable of producing radiographic opacities that will be interpreted as compatible with pneumoconiosis when employing the International Labour Organization [1980] (ILO) classification Castellan et al., 19851. Neither camp emphasizes the important clinical, epidemiologic, and medicolegal implications of these positions, even though they are the leitmotif underscoring the reasoned scientific discourse [Blanc and Gamsu, 1988; Weeks and Wagner, 19861. We consider that the bulk of the evidence shows that application of the standardized radiographs from the ILO classification must be the keystone to any structured analysis of cigarette smoking in relation to the pneumoconioses. The ILO system is not ideal and its shortcomings, including inter-and intraobserver variability, lack of specificity, and its semiquantitative nature, are well known Kilburn, 19881. Nevertheless, the ILO system permits reliable comparison among different studies. The ILO standard radiographs also apparently discriminate between opacities consistent with pneumoconiosis and the diffuse lung abnormalities seen in cigarette smokers or chronic bronchitics. The concept of restricting analysis to the ILO system is far from revolutionary, but it has not been systematically applied to the cigarette smoking issue.
Studies that use the ILO standard radiographs clearly show that cigarette