Prevalence of silicosis among in-service Zambian copper miners

Abstract

Objectives To determine the prevalence of silicosis among the in-service Zambian copper miners and identify which areas of operations and mines are mostly affected by silicosis. Design: Cross-sectional point prevalence. Setting: Medical records of miners from Occupational Health Research Bureau Kitwe-Zambia. Subjects and methods: 1122 miners who had worked for more than ten years in the scheduled area were randomly selected for the study from the Bureau records. Data was analyzed in Stata for descriptive summaries associations of silicosis with and independent variables. Results: The prevalence of silicosis was 8 per 1000 miners with Chibuluma mine recording the highest prevalence2.2%(1 out of 27) and with the dust producing areas recording the highest prevalence 6 out of the 9 cases (66.6% ). All the cases were from underground miners and were above 40 years of age. Silicosis was strongly associated with years of service, age of the miners and area of operations (p <0.05). Association was shown between silicosis and dust particles in chi-square test of association, but when put in binary logistic regression there was no association (p 0. 7) probably because dust particle levels was used instead of respirable free silica and the different mines contain different silica levels in their virgin rocks. If respirable free silica levels were used the association could have been there. This can be confirmed by the high prevalence in dust producing areas. Conclusion: The prevalence of silicosis among the in-service Zambia copper mines is low compared to other mining countries. There is a possibility of high prevalence among the retirees since all of them are more than 40years of age and there is strong association between years of service age, and areas of operation with silicosis.