Tw. Steen et al., PREVALENCE OF OCCUPATIONAL LUNG-DISEASE AMONG BOTSWANA MEN FORMERLY EMPLOYED IN THE SOUTH-AFRICAN MINING-INDUSTRY, Occupational and environmental medicine, 54(1), 1997, pp. 19-26
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.