The Department of Environmental Quality proposed amendments to R307-101-2, Definitions. These changes update the version of Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices referenced in several definitions in Section R307-101-2. All references to Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices need to be consistent and up-to-date to ensure that the most recently published Threshold Limit Values constitute the basis of regulatory actions and requirements. http://www.rules.utah.gov/publicat/bulletin/2009/20090415/32458.htm.