Comparison of radiographic appearances with associated pathology and lung dust content in a group of coalworkers.

Abstract

The pathology and dust content of lungs from 261 coalminers in relation to the appearances of their chest radiographs taken within four years of death were examined. Radiological opacities of coalworkers' pneumoconiosis were more profuse the more dust was retained in lungs. Among the men who had mined low rank coal-that is, with a relatively high proportion of ash-the increase in profusion was most closely related to the ash component of the dust, whereas in men who had mined high rank coal both coal and ash increased in the lungs in relation to radiological profusion. The fine p type of opacity was found to be associated with more dust and a higher proportion of coal and less ash than the nodular r opacity, and was also more likely to be associated with emphysema. The pathological basis of the different types of opacity found on the radiographs of coalminers related to the number, size, and nodularity of the dust lesions. Larger fibrotic lesions were likely to appear as r opacities, whereas fine reticular dust deposition was most likely to present as p opacities, q opacities showing a mixture of appearances. The study has shown that the composition of dust retained in the lung, as well as its amount, makes an important contribution to the radiographic appearances of pneumoconiosis. In particular, the r type of lesion on the radiograph of a low rank coalminer indicates the possibility of a silicotic like lesion.The relation between exposure to coalmine dust and the radiographic profusion of small opacities in simple pneumoconiosis has been well documented. '-3 The primary relation appears to be with exposure to mixed respirable dust, and no generally applicable additional effect of the ash component of the dust has been shown.3 Consequently it seems logical to suppose that radiographic opacities are due largely to an accumulation of dust and, indeed, such an association between retained dust and profusion of opacities has been clearly shownm.45Most workers, however, describe groups in which the radiological changes appear disproportionate for the amount of dust in the lungs and recognise that factors other than the mass of retained dust contribute to the radiographic picture. It has been noted, for example, that the higher the proportion of coal in the retained dust, the more dust is required to produce a given radiological category,6 and Caplan found that the radiological category was more closely associated with the profusion of fibrotic nodules in the lung than with the profusion of dust foci of all types.7The principal aim of the present study was to examine further the factors that affect the relation between the profusion of small opacities and the mass of retained lung dust. Additional aims were to determine the pathological basis for the three types of small rounded opacity and to verify the reported association of both the p type of small rounded opacity8 and irregular opacities9 with the presence of emphysema. Methods SOURCE AND CLASSIFICATION OF RADIOGRAPHSThe study was based on 261 men drawn from a...

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