PREVALENCE OF OCCUPATIONAL LUNG-DISEASE AMONG BOTSWANA MEN FORMERLY EMPLOYED IN THE SOUTH-AFRICAN MINING-INDUSTRY

Objective-To determine whether previous health experiences affect the prevalence of occupational lung disease in a semirural Botswanan commu nity where there is a long history of labour recruitment to South Afri can mines. Method-A cross sectional prevalence study of 304 former min ers examined according to a protocol including a questionnaire, chest radiograph, spirometry, and medical examination. Results-Overall mean age was 56.7 (range 28-93) years, mean duration of service 15.5 (range 2-42) years. 26.6% had a history of tuberculosis. 23.3% had experienc ed a disabling occupational injury. Overall prevalence of pnemoconiosi s (> 1/0 profusion, by the International Labour Organisation classific ation) was 26.6%-31.0%, and 6.8% had progressive massive fibrosis (PMF ). Many were entitled to compensation under South African law. Both ra diograph readers detected time response relations between pneumoconios is and PMF among the 234 underground gold miners. PMF could result fro m < 5 years of exposure, but was not found < 15 years after first expo sure. Both pulmonary tuberculosis (PTB) and pneumoconiosis were found to be associated with airflow limitation. Conclusions--Former miners i n Botswana have a high prevalence of previously unrecognised pneumocon iosis, indicative of high previous exposures to fibrogenic respirable dust. Their pneumoconiosis moconiosis went unrecognised because they h ad no access to surveillence after employment. Inadequate radiographic surveillence or failure to act on results when employed or when leavi ng employment at the mines could have contributed to underrecognition. Community based studies of former miners are essential to fully evalu ate the effects of mining exposures. Our findings indicate a failure o f established measures to prevent or identify pneumoconiosis while the se miners were in employment and show that few of the social costs of occupational lung diseases are borne by mining companies through the c ompensation system.