Impact of contracting on occupational injuries and fatalities in underground coal mining

Background: Contracting out of mining operations has increased significantly in the underground coal mining industry over the last decade. Contract miners are hired by coal operators to extract coal, usually for a specified price and using equipment often leased from the operator or mine controller. We hypothesize that the market and organizational incentives facing contractors increase the likelihood of traumatic injuries and fatalities to their workforce relative to miners working directly for operators in comparable mines. We further hypothesize that contracting has larger effects on health and safety outcomes in mines that are not vertically integrated (i.e. where a controller does not own both processing and mining facilities) and where the controller of the mine using contractors has a high rate of prior violations with the Mine Safety and Health Act. Methods: We test this hypothesis using data from the Mine Safety and Health Administration for the period 2000-2012. We statistically model the determinants of injuries and fatalities based on contract status along with mining methods, geologic characteristics, union status, size of mine and controller, and prior history of violations. Results: Our preliminary findings suggest increased risk exposure for contract miners, particularly in a subset of non-vertically integrated mining operations. We also find interaction effects between prior violation experience of mine controllers with the health and safety outcomes of their contractors. Conclusions: These findings have important implications for enforcement and public policies and extend the findings of the adverse impact of subcontracting on health and safety to the mining sector.