ACGIH® announced today the release of its two-tier Under Study list pursuant to changes previously made to its TLV®/BEI® Development Process.

In 2006, ACGIH® began providing additional information on the status of chemical substances and physical agents that are on the Under Study list. In addition to the practice of publishing an updated Under Study list on the ACGIH® website (, in the ACGIH® Annual Reports by February 1 of each year, and in the annual TLVs® and BEIs® book, the Under Study list will be updated annually by July 31 and presented in a two-tier list. Tier 1 entries indicate which chemical substances and physical agents may move forward as an NIC or NIE in the upcoming year, based on their status in the development process. Tier 2 consists of those chemical substances and physical agents that will not move forward, but will either remain on, or be removed from the Under Study list for the next year.

This process is designed to provide the public with information of significant relevance regarding the development status of a substance or agent, increase the transparency and clarity of our process regarding those substances and agents on the Under Study list, and provide additional information that may help interested parties prioritize their efforts for submitting information or comments to the Committee. The updated list will remain in two-tiers for the balance of the year. ACGIH® will continue this practice of updating the Under Study list by February 1 and establishing the two-tier list by July 31 each year.

To view the 2019 two-tier list, visit the ACGIH® website at

ACGIH® recommends that all TLV® and BEI® users read the Statement of Position Regarding the TLVs® and BEIs® that outlines the proper usage of TLVs® and BEIs®. The Statement of Position can be found in the TLV®/BEI® Guidelines section of the ACGIH® website ( In addition to the Statement of Position, visitors to this site will find other useful information on TLVs® and BEIs®, including the following:

ACGIH® is a 501(c)(3) charitable scientific organization that advances occupational and environmental health.   ACGIH® is one of the industry’s leading publications resources, with approximately 400 titles relative to occupational and environmental health and safety, including the renowned TLVs® and BEIs®. For more information, visit the ACGIH® website at or call our Customer Service Representatives at 513-742-2020.