Roentgenographic underestimation of early asbestosis by International Labor Organization classification. Analysis of data and probabilities.

We analyzed the limitations of the International Labor Organization (ILO) classification of chest roentgenograms in predicting the presence of histologically determined early asbestosis. The ILO system is arbitrary, without histologic correlates, and does not consider the asbestos exposure history or clinical and laboratory information. We present data from the literature and our own work which demonstrate that the application of the ILO classification to an asbestos-exposed individual can result in a 10 to 20 percent probability of a "normal" roentgenographic interpretation in the presence of significant asbestosis at the histologic level, leading to an inappropriate conclusion regarding the presence of asbestosis. In view of the data and statistical analysis presented, we suggest that sole reliance upon the ILO classified chest roentgenogram for determination of the presence of early pulmonary asbestosis in individual cases is inappropriate.