ACGIH
Either: (a) the American Conference of Governmental Industrial Hygienists publication entitled Threshold Limit Values and Biological Exposure Indices, dated 2002, as amended from time to time, or (b) the American Conference of Governmental Industrial Hygienists publication entitled Documentation of the Threshold Limit Values and Biological Exposure Indices, as amended from time to time.
Source
WorkSafeBC's OHSR 5.1 (Definitions)