Today, the TLV®-CS Committee has emerged as the best known of ACGIH®’s scientific committees. Established in 1941, this group was charged with investigating, recommending, and annually reviewing exposure limits for chemical substances. It became a standing committee in 1944. Two years later, the organization adopted its first list of 148 exposure limits, then referred to as Maximum Allowable Concentrations. The term “Threshold Limit Values (TLVs®)” was introduced in 1956. The first edition of Documentation of the Threshold Limit Values was published in 1962 and is now in its seventh edition. Today’s list of TLVs® includes over 700 chemical substances.