Risk Factors Associated with Silicosis among Zambian Copper Mine Workers: A Retrospective Case Record Review

Abstract Background: Silicosis is the most important occupational disease worldwide and is regarded as a major public health challenge in developing countries. The disease is mainly related to exposure to crystalline silica dust, and once the disease has been established, no treatment exists. There is less focus on other factors that are related to one acquiring the disease among the people at greater risk of developing silicosis. The main aim of this study was to assess the risk factors associated with developing silicosis among Konkola Copper Mine workers in Zambia. Methods: A retrospective case review study was used, consisting of 168 Konkola Copper Mine Workers. A data extraction checklist was used to collect data on miners from the occupational hygiene silicosis registers. Data was analyzed using STATA version 12.0; a quantile-quantile plot was used to test for normality of continuous variables such as age and a chi-squared test was used to ascertain association with development of silicosis. Adjustment for the effect of other factors was computed using an investigator led stepwise multiple logistic regression method. Results: For each year increase in length of service, Konkola Copper Miners are 1.95 times more likely to develop silicosis adjusting for other factors such as business unit, job category (95% CI 1.92-1.99, p=0.033). Miners working in the production areas were highly susceptible to developing silicosis compared to those working in other areas. Within the production area, miners working underground represented 38% of silicosics, while those working at open pit only had 10%. Miners belonging to Konkola and Nchanga business unit were 5.42 and 5.96 times more likely to develop silicosis compared to those working in other units respectively. Conclusions: As a result of the statistical analysis, our findings suggest that the factors considered best predictors of silicosis were length of service, business unit and the job category to which the miners belonged to (P-values 0.033, 0.001, <0.001 respectively). There is need to reduce the length of service that individuals work underground, strengthen control measures regarding utilization of personal protective equipment, health education programs, frequent job rotations (for unskilled labour) and adherence to periodical medical examinations.