1.1 This guide covers recommended procedures for maintaining and handling hazardous biological materials at liquid nitrogen temperatures. 1.2 This guide covers the safety precautions recommended when handling material stored in liquid nitrogen. 1.3 This guide does not cover the maintenance and handling of hazardous biological materials maintained at cryogenic temperatures in systems other than liquid nitrogen. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.