A cohort study of graphite workers in Sri Lanka.

A cohort of workers from a graphite mine in Sri Lanka was studied in 1987, 1990 and 1993. Radiographic lesions were found in 8.5%, 8.9% and 4.1% of the workers in these respective rounds. When workers with radiographic lesions were clinically examined, a total of 18 cases of graphite pneumoconiosis and seven cases of active pulmonary tuberculosis were detected in the three rounds. The prevalence of both these diseases showed a decline in 1993 when compared to 1987. This favourable situation was probably the result of dust control measures introduced in the mine after 1972. Five workers developed graphite pneumoconiosis in the course of the study. They had worked in the mine for an average of 22.6 years. The right lung appeared to be more vulnerable than the left.