Laboratory biosafety manual, fourth edition

xviiForewordThe first edition of the World Health Organization (WHO) Laboratory biosafety manualwas published in 1983. It encouraged countries to accept and implement basic concepts in biological safety and to develop national codes of practice for the safe handling of pathogenic biological agents in laboratories within their geographical borders. Since then, many countries have used the expert guidance provided in the manual to develop such codes of practice. The second and third editions of the Laboratory biosafety manual were published in 1993 and 2004 respectively. With each new version, WHO continues to provide international leadership on biosafety by addressing emerging issues, technologies and challenges, and providing guidance on best practice. Previous versions of the manual described the classification of biological agents and laboratories in terms of risk/hazard groups and biosafety/containment levels. While this may be a logical starting point for the handling and containment of biological agents, it has led to the misconception that the risk group of a biological agent directly corresponds to the biosafety level of a laboratory. In fact, the actual risk of a given scenario is influenced not only by the agent being handled, but also by the procedure being performed and the competency of the laboratory personnel engaging in the laboratory activity.This fourth edition of the manual builds on the risk assessment framework introduced in the third edition. A thorough, evidence-based and transparent assessment of the risks allows safety measures to be balanced with the actual risk of working with biological agents on a case-by-case basis. This will enable countries to implement economically feasible and sustainable laboratory biosafety and biosecurity policies and practices that are relevant to their individual circumstances and priorities.