The source of injury in CFOI identifies the object, substance, or person that generated the injury, or that contributed to the incident [BLS, 2012a]. BLS coded source information based on the BLS-developed Occupational Injury and Illness Classification System (OIICS) version 1.01 [BLS, 2007]. We used the OIICS source codes to identify cases for this study where the primary source of injury was a machine. Machines were categorized into two separate groups, mobile or stationary, based on the OIICS source of injury (Table I). Although the OIICS category for machines (OIICS source code = “3”) does not include forklifts and tractors (OIICS source code = “85”), they were included as machines in this analysis.