Epidemiological research on the causes of occupational traumatic injuries presents interesting practical and conceptual challenges. On a superficial level, the causation of injuries seems deceptively simple, because the agent of injury—energy—is already known. One of the problems researchers face, however, is that the transfer of potentially harmful energy to a human host is difficult to observe because it takes place very quickly and is rarely recorded or documented in databases. New studies are beginning to take up these challenges with innovative approaches like the case-crossover design.¹ Another challenge, perhaps conceptually more difficult, is that because the agent of injury is known, its discovery is not an important research problem. Instead, it is the “upstream” causes² of injury—the events and circumstances that bring people into contact with the agent—that are of interest. Some studies published recently in this journal have investigated potential causes upstream of the injured worker, ranging in proximity from the organisation of workplaces³ to the structure …