| In a study of living and deceased South African coal miners, the prevalence of dust related respiratory problems and dose response relationships between health endpoints and respirable dust, were investigated. Coalminer autopsies (n = 7760) performed between 1975 and 1997 were reviewed, and exposure and respiratory health outcomes were assessed among active (n = 684) and ex-miners (n = 212), employed for at least one year in underground mining between 1985 and 1998 in one of three mines in Mpumalanga province. Associations were investigated between exposure measures and respiratory outcomes, based on questionnaires, spirometry and radiographs. Cumulative exposure to respirable dust was estimated through historical and current dust samples, work histories, miner interviews and other record reviews.; Historic exposure levels and investigator collected dust data across the mines ranged from averages of 1.30–2.56mg/m3 at the coalface. The prevalences of respiratory diseases were: radiological coalworkers' pneumoconiosis: 2.59%; reported TB: 3.00% and symptoms of chronic bronchitis: 11.30%. The estimate of dust related effect on FEV1 for a 40 year old, 1.70m tall man, was 1.33ml per mg-years/m3, adjusted for smoking and past history of TB. Past history of TB resulted in an average 698ml decline in FEV1. Miners with the significant respiratory problems and the greatest dose response to dust exposure were more likely to leave employment before normal retirement age or move from high to lower exposed jobs.; At autopsy, the prevalences were: CWP (6.95%), silicosis (10.22%) and moderate to marked emphysema (6.45%). A high exposure category miner (12 to 55 years of work in a coalmine) had a 15 times greater chance of emphysema compared to one in a lower exposure category (0.1 to 3.5 years), adjusting for the effects of smoking. Smoking status (ever versus never smoker) resulted in a two times greater risk of emphysema.; Based on the complementary findings of exposure related decrements in lung function and exposure related risk for emphysema., coaldust exposures contribute to respiratory disease, under currently prevailing conditions.; Recommendations include increased engineering controls and work practices designed to minimise exposure, enforcement of statutory occupational exposure aimed at progressive reduction and ensuring respiratory medical surveillance programmes are instituted. |
