OBJECTIVETo explore the integrative quantitative index of the extent of pneumoconiotic changes by dusts and to evaluate the extent of pulmonary injury by the dusts containing different contents of free silica.

METHODSIn accordance with the morphometric principle, the areas of each kind of pathologic changes in the lung tissue sections of pneumoconiosis model were measured by utilizing a computer-aided graphic analyzer, and the volume density of each pathologic change and the value of pulmonary injury by dust(VPID) were calculated. Meanwhile the extent of pulmonary injury were compared among the rat groups treated with the dusts containing different contents of free silica.

RESULTSThere were significant differences among each groups in the volume density of some pathologic changes in the same exposed periods. There were significant correlation between VPID and the content of free silica dust or the lung collagen content (r = 0.535-0.849, P < 0.005 or P < 0.01). Furthermore, the degree of cor relationship of VPID with both of the latter were higher than the sum of unweighted volume density of the various pathologic changes in lung.

CONCLUSIONIt is suitable, reasonable and simple to use VPID an index to indicate the extent of pulmonary injury by dust and to diagnose pneumoconiosis in pathology, and the extent of pulmonary injury by dust may be aggravated with the increasing of the content of free silica.