Rapid progression of silicosis in slate pencil workers: II. A follow-up study.

Findings of the follow-up examination of slate-pencil workers after 16 months are described. The progression of silicosis with this short duration was very rapid with high mortality among those who had conglomerate silicosis at the initial examination. Twenty-three workers had died during this period at a mean age of only 34.7 years, with a mean duration of exposure of 11.9 years. This high mortality is attributed to exposure to high concentrations of silica dust leading to early onset of PMF at a relatively young age. The progression of silicosis within this period was related to the intensity and duration of dust exposure, and also to the severity of silicosis found at the initial examination. Smoking habits had an adverse, though statistically nonsignificant, effect on the evolution of silicosis.