Prevalence characteristics and prediction of coal workers' pneumoconiosis in the Tiefa Colliery in China.

To explore characteristics of the development of coal workers' pneumoconiosis (CWP) at present and trend in the future, we investigated 16,154 coal miners exposed to dust for at least 1 yr in the Tiefa Colliery in China. Occupational categories were divided into tunneling, mining, combining and helping. Four cohorts (before 1958, 1958-, 1968-, and after 1978) were created according to years of first exposure. Life-Table Method was used to calculate cumulative incidence rates of CWP adjusted by duration of dust exposure and predict the number of the new CWP patients. Results indicated that cumulative incidence rates of CWP in four cohorts were 26.65%, 18.94%, 1.15%, and 0.06%, respectively (Chi(2)=493.57, p<0.0001). The 55-yr cumulative rate of CWP of tunneling miners (25.90%) or that of combining miners (14.53%) was statistically higher than that of mining miners (7.26%) or that of helping miners (0.89%). The number of new CWP patients predicted in future was approximately 77. New CWP patients predicted would mainly occur among coal miners with first dust exposure in 1958-1967 and those working at tunneling. Most of them could be diagnosed in the age group from 45 to 75 and in the period of the next 20 yr from 2008 to 2028.