Microorganisms are widely used in various beneficial applications, including food, pest control, bioremediation, biodegradation, biofuel processes, and plant symbiosis and growth stimulation. This book provides an overview of the available methodology for safety assessments of microorganisms, including determination of their infectivity and whether they produce toxic or sensitizing substances. Also covered are the regulatory systems in risk assessment and management of microbial products, quarantine legislations, international treaties, the importance of public risk perception and risk reduction behavior.