Frequency of black pigment in livers and spleens of coal workers: correlation with pulmonary pathology and occupational information.

Histologic sections of liver and spleen from 99 retired coal workers and nine non-coal workers were obtained at autopsy and scored for black pigment. Pigment was minimal in the non-coal workers, with the exception of one person with silicosis. Moderate or heavy pigment was seen in 10.4 per cent of liver sections and 19.5 per cent of spleen sections from coal workers. The extrapulmonary pigment was not associated with any pathologic tissue response. Information on pulmonary pathology and occupational exposure to dust was available for most workers. Highly significant positive correlation was found between the severity of pneumoconiosis and the black pigment score in both liver and spleen; the correlation between emphysema and pigment score was lower, but still significant for liver. Significant positive correlations were found between years spent underground, years of retirement, and age at death versus pigment scores. Significant negative correlation was found between smoking and pigment. The positive association of extrapulmonary pigment with age at death, years of underground mining, and severity of pneumoconiosis suggests that cumulative lifetime exposure to coal mine dust may be the most important factor in the release of dust into the general circulation.