TLV®/BEI® Development Process

Provided below is an overview of the ACGIH® TLV®/BEI® Development Process. Additional information is available on the ACGIH® website ( Please also refer to the Process Flowchart (Figure 1).

  1. Under Study: When a substance or agent is selected for the development or revision of a TLV® or BEI®, the appropriate committee places it on its Under Study list. Each committee determines its own selection of chemical substances or physical agents for its Under Study list. A variety of factors is used in this selection process, including prevalence, use, number of workers exposed, availability of scientific data, existence/absence of a TLV® or BEI®, age of TLV® or BEI®, input from the public, etc. The public may offer input to any TLV® or BEI® Committee by e-mail to

    The Under Study lists serve as notification and invitation to interested parties to submit substantive data and comments to assist the committees in their deliberations. Each committee considers only those comments and data that address issues of health and exposure, but not economic or technical feasibility. Comments must be accompanied by copies of substantiating data, preferably in the form of peer-reviewed literature. Should the data be from unpublished studies, ACGIH® requires written authorization from the owner of the studies granting ACGIH® permission to (1) use, (2) cite within the Documentation, and (3) upon request from a third party, release the information. All three permissions must be stated/covered in the written authorization. (See endnote for a sample permission statement.) Electronic submission of all information to the ACGIH® Science Group at is preferred and greatly increases the ease and efficiency with which the committee can consider the comments or data.

    The Under Study list is published each year by February 1 on the ACGIH® website (, in the Annual Reports of the Committees on TLVs® and BEIs®, and later in the annual TLVs® and BEIs® book. In addition, the Under Study list is updated by July 31 into 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 updated list will remain in two-tiers for the balance of the year. All updates to the Under Study lists and publication of the two-tier lists are posted on the ACGIH® website (  
  2. Draft Documentation: One or more members of the appropriate committee are assigned the task of collecting information and data from the scientific literature, reviewing results of unpublished studies submitted for review, and developing a draft TLV® or BEI® Documentation. The draft Documentation is a critical evaluation of the scientific literature relevant to recommending a TLV® or BEI®; however, it is not an exhaustive critical review of all studies but only those pertinent to identifying the critical effect and setting the TLV®. Particular emphasis is given to papers that address minimal or no adverse health effect levels in exposed animals or workers that deal with the reversibility of such effects, or in the case of a BEI®, that assess chemical uptake and provide applicable determinant(s) as an index of uptake. Human data, when available, are given special emphasis. This draft Documentation, with its proposed TLV® or BEI®, is then reviewed and critiqued by additional committee members, and eventually by the full committee. This often results in several revisions to the draft Documentation before the full committee accepts the proposed draft TLV® or BEI® and draft Documentation. The draft Documentation is not available to the public during this stage of the development process and is not released until it is at the Notice of Intended Changes (NIC) stage. Authorship of the Documentation is not disclosed.

  3. Notice of Intended Changes (NIC):
    [Notice of Intent to Establish (NIE): The Physical Agents section of the TLVs® and BEIs®book also uses the term Notice of Intent to Establish (NIE) in addition to NIC. An NIE follows the same development process as an NIC. For purposes of this process overview, only the term NIC is used.]

    When the full committee accepts the draft Documentation and its proposed TLV® or BEI®, theDocumentation and proposed values are then recommended to the ACGIH® Board of Directors for ratification as an NIC. If ratified, each proposed TLV® or BEI® is published as an NIC in the Annual Reports of the Committees on TLVs® and BEIs®, which is published in the ACGIH® member newsletter, Today! Online and is also available online for purchase at At the same time, the draft Documentation is made available through ACGIH® Customer Service or online at All information contained in the Annual Reports of the Committees on TLVs® and BEIs® is integrated into the annual TLVs® and BEIs® book, which is usually available to the general public in February or March of each year. Following the NIC ratification by the ACGIH® Board of Directors, interested parties, including ACGIH® members, are invited to provide data and substantive comments, preferably in the form of peer-reviewed literature, on the proposed TLVs® or BEIs® contained in the NIC. Should the data be from unpublished studies, ACGIH® requires written authorization from the owner of the studies granting ACGIH®permission to (1) use, (2) cite within the Documentation, and (3) upon request from a third party, release the information. All three permissions must be stated/covered in the written authorization. (See endnote for a sample permission statement.) The most effective and helpful comments are those that address specific points within the draft Documentation. Changes or updates are made to the draft Documentation as necessary. If the committee finds or receives substantive data that change its scientific opinion regarding TLV® or BEI® values or notations, the committee may revise the proposal(s) and recommend to the ACGIH® Board of Directors that it be retained on the NIC.

    Important Notice: The comment period for an NIC or NIE draft Documentation and its respective TLV(s)®, notation(s), or BEI(s)®, will be limited to a firm 4-month period, running from February 1 to May 31 of each year. ACGIH® has structured the comment period to ensure all comments are received by ACGIH® in time for full consideration by the appropriate committee before its fall meeting. Because of the time required to properly review, evaluate, and consider comments during the fall meetings, any comments received after the deadline of May 31 will not be considered in that year's committee deliberations regarding the outcome for possible adoption of an NIC or NIE. As general practice, ACGIH® reviews all submissions regarding chemical substances and physical agents on the Under Study list, as well as NICs or NIEs, or currently adopted BEI(s)® or TLV(s)®. All comments received after May 31 will be fully considered in the following year. DraftDocumentation will be available for review during the comment period.

    When submitting comments, ACGIH® requires that the submission be limited to 10 pages in length, including an executive summary. The submission may include appendices of citable material not included as part of the 10-page limit. It would be very beneficial to structure comments as follows:

    1. Executive Summary – Provide an executive summary with a limit of 250 words.
    2. List of Recommendations/Actions – Identify, in a vertical list, specific recommendations/actions that are being requested.
    3. Rationale – Provide specific rationale to justify each recommendation/action requested.
    4. Citable Material – Provide citable material to substantiate the rationale.

    The above procedure will help ACGIH® to more efficiently and productively review comments.

  4. TLV®/BEI® and Adopted Documentation: If the committee neither finds nor receives any substantive data that change its scientific opinion regarding an NIC TLV® or BEI® (or notation), the committee may then approve its recommendation to the ACGIH® Board of Directors for adoption. Once approved by the committee and subsequently ratified by the Board, the TLV® or BEI® is published as adopted in the Annual Reports of the Committees on TLVs® and BEIs® and in the annual TLVs® and BEIs® book, and the draft TLV® or BEI® Documentation is finalized for formal publication.

  5. Withdraw from Consideration: At any point in the process, the committee may determine not to proceed with the development of a TLV® or BEI® and withdraw it from further consideration. Substances or physical agents that have been withdrawn from consideration may be reconsidered by placement on the Under Study list (step 1 above).

     There are several important points to consider throughout the above process:

    1. The appropriate method for an interested party to contribute to the TLV® and BEI® process is through the submission of literature that is peer-reviewed and public. ACGIH® strongly encourages interested parties to publish their studies, and not to rely on unpublished studies as their input to the TLV® and BEI® process. Also, the best time to submit comments to ACGIH®is in the early stages of the TLV® and BEI® Development Process, preferably while the substance or agent is on the Under Study list.


    2. An additional venue for presentation of new data is an ACGIH®-sponsored symposium or workshop that provides a platform for public discussion and scientific interpretation. ACGIH®encourages input from external parties for suggestions on symposium topics, including suggestions about sponsors, speakers and format. ACGIH® employs several criteria to determine the appropriateness of a symposium. A key criterion is that the symposium must be the most efficient format to present the committee with information that will assist in the scientific judgment used for writing the Documentation and in setting the respective TLVs® or BEIs®. A symposium topic should be suggested while the substance/agent is under study, as symposia require considerable time, commitment, and resources to develop. Symposium topic suggestions submitted while a substance is on the NIC will be considered, but this is usually too late in the decision-making process. A symposium topic will not be favorably considered if its purpose is to provide a forum merely for voicing opinions about existing data. Rather, there must be on-going research, scientific uncertainty about currently available data, or another scientific reason for the symposium. Symposium topic suggestions should be sent to the ACGIH® Science Group (


    3. ACGIH® periodically receives requests from external parties to make a presentation to a committee about specific substances or issues. It is strictly by exception that such requests are granted. While there are various reasons for this position, the underlying fact is that the committee focuses on data that have been peer-reviewed and published and not on data presented in a private forum. A committee may grant a request when the data are significantly new, have received peer review, are the best vehicle for receipt of the information, and are essential to the committee's deliberations. The presentation is not a forum to merely voice opinions about existing data. In order for a committee to evaluate such a request, the external party must submit a request in writing that, at a minimum, addresses the following elements: (a) a detailed description of the presentation; (b) a clear demonstration of why the information is important to the committee's deliberations; and (c) a clear demonstration of why a meeting is the necessary method of delivery. This request must be sent to the ACGIH® Science Group (

      Also, the committee may initiate contact with outside experts (a) to meet with the committee to discuss specific issues or to obtain additional knowledge on the subject, and (b) to provide written input or review of a Documentation. This is only done on an as needed basis, and not as a routine practice.

    4. ACGIH® does not commit to deferring consideration of a new or revised TLV® or BEI® pending the outcome of proposed or ongoing research.


    Important dates to consider throughout each calendar year of the TLV®/BEI® Development Process:

    First Quarter:

    Year Round

    • Public comments are accepted. See Note below.


    • Committees meet.
    Note: It is recommended that comments be submitted as early as practical, and preferably no later than May 31st to allow sufficient time for their proper consideration/review. This is particularly important for an NIC TLV®/BEI®.


    Important Notice: The comment period for an NIC or NIE draft Documentation and its respective TLV(s)®, notation(s), or BEI(s)®, will be limited to a firm 4-month period, running from February 1 to May 31 of each year. (See Important Notice, step 3 above.)

    Third Quarter:

    Fourth Quarter
    : *

    • TLV®/BEI® Committees vote on proposed TLVs®/BEIs® for NIC or final adoption.


    • ACGIH® Board of Directors votes on ratification of TLV®/BEI® Committee recommendations.
    * These actions typically occur early in the fourth quarter, but may occur during other periods of the quarter or year.

    Endnote: Sample permission statement granting ACGIH® authorization to use, cite, and release unpublished studies:


    [Name], [author or sponsor of the study**] grants permission to ACGIH® to use and cite the documents listed below, and to fully disclose them to parties outside of ACGIH® upon request. Permission to disclose the documents includes permission to make copies as needed.

    Example: Joseph D. Doe, PhD, co-author of the study, grants permission to ACGIH®to use and cite the document listed below, and to fully disclose this document to parties outside of ACGIH®. Permission to disclose the document includes permission to make copies as needed.

    "Effects of Quartz Status on Pharmacokinetics of Intratracheally Instilled Cristobalite in Rats. March 21, 2003."
    **This statement must be signed by an individual authorized to give this permission, and should include contact information such as title and address.

    Last Revised April 2012