TLVs® (Threshold Limit Value) and BEIs® (Biological Exposure Indices) are often recognized as “safe levels” for worker exposures to chemical substances and physical agents. ACGIH®, a non-profit scientific association, develops and annually summarizes TLVs® and BEIs® in a booklet (2019 booklet is about 300 pages) available at www.acgih.org. Proper application of TLVs® and BEIs® are essential to today’s practice of industrial hygiene (IH).
TLVs® originated in the 1930s. TLVs® are intended for voluntary guidance but often find their way into regulations. OSHA’s first PELs, for example, were derived from ACGIH’s 1968 TLVs® list. OSHA’s 2012 HazCom standard requires that voluntary TLVs®, along with mandatory OSHA PELs, must be included on applicable Safety Data Sheets.