Abstract
A study of respiratory function and symptoms in Brazilian coal miners was conducted. The cohort consisted of 956 persons, mean age 30.7 years, employed at six underground mines in the Santa Catarina coal district of Brazil. Company supplied chest X-ray films were read for evidence of pneumoconiosis. Information on the number of years spent in underground coal mining and smoking was obtained. The number of years in underground mining (NYE) was used as a surrogate for coal dust exposure. The mean NYE of the cohort was 5.8 years. Forty subjects, 5.6%, had radiological evidence of pneumoconiosis. The mean NYE of these subjects was 8.4 years. Approximately 34.7% of the subjects reported cough, 39.5% phlegm, and 30.4% breathlessness. Approximately 33% of the miners with valid lung function tests had significantly decreased 1 second forced expiratory volume (FEV1) and forced vital capacity (FVC) values less than 80% of the predicted values. Approximately 60.7% of the miners were smokers, 13.4% were exsmokers, and the rest nonsmokers. The NYE and pack years of smoking were significantly correlated with the prevalence of cough, phlegm, and breathlessness. The NYE was significantly, negatively correlated with the FEV1/FVC ratio. Multiple linear regression analysis indicated that NYE followed by breathlessness were the most important factors related to pneumoconiosis. Probit analysis showed that the risk of developing pneumoconiosis was significantly, positively correlated with the FEV1/FVC ratio and negatively correlated with the FEV1. The authors conclude that Brazilian coal miners have an excess of respiratory symptoms that is significantly related to coal dust exposure and smoking. Coal dust exposure is the most important factor for determining the risk of pneumoconiosis.
