Closed System Transfer Devices: Enhancing Safety When Handling Hazardous Drugs What is a CSTD?A closed system transfer device (CSTD) is a medical device that mechanically prohibits the transfer of environmental contaminants into a system and the escape of hazardous drug or vapor concentrations out of the system. CSTDs provide a means of transferring hazardous drugs from one component to another while containing exposure throughout the process. Traditional methods of...