A memo from the Occupational Safety and Health Administration illustrates "the burden faced by some of America’s 2.5 million temporary, or contingent, workers — a growing but mostly invisible group of laborers who often toil in the least desirable, most dangerous jobs. Such workers are hurt more frequently than permanent employees and their injuries often go unrecorded, new research shows."

Jim Morris and Chip Mitchell report for the Center for Public Integrity and WBEZ December 20, 2012. [2]