Threshold Limit Values (TLVs®) and Biological Exposure Indices (BEIs®) are determinations made by a voluntary body of independent knowledgeable individuals. They represent the opinion of the scientific community that has reviewed the data described in the Documentation, that exposure at or below the level of the TLV® or BEI® does not create an unreasonable risk of disease or injury.

TLVs® and BEIs® are not standards. They are guidelines designed for use by industrial hygienists in making decisions regarding safe levels of exposure to various chemical substances and physical agents found in the workplace. In using these guidelines, industrial hygienists are cautioned that the TLVs® and BEIs® are only one of multiple factors to be considered in evaluating specific workplace situations and conditions.

TLVs® and BEIs® are health-based values established by committees that review existing published and peer-reviewed literature in various scientific disciplines (e.g., industrial hygiene, toxicology, occupational medicine, and epidemiology). Since TLVs® and BEIs® are based solely on health factors, there is no consideration given to economic or technical feasibility.

This section of the ACGIH® website has been established to help educate industry, government, and the public on what TLVs® and BEIs® are, and how TLVs® and BEIs® may best be used. It has also been established to increase the transparency of the TLV®/BEI®process and to promote a better understanding of, and participation between, occupational hygienists and other interested parties.

Questions not answered here should be referred to The Science Group, ACGIH®.

Biological Exposure Indices Committee
Threshold Limit Values for Chemical Substances Committee
Threshold Limit Values for Physical Agents Committee