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Request for the Technical Review of the Draft Current Intelligence Bulletin (CIB): Derivation of Immediately Dangerous to Life and Health (IDLH) Values

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National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC), Department of Health and Human Services (HHS).


Notice of public comment period.


The National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC) is conducting a public review of the draft, Current Intelligence Bulletin (CIB): Derivation of Immediately Dangerous to Life and Health (IDLH) Values. NIOSH is requesting technical review of the draft CIB. The draft document and instructions for submitting comments can be found at​niosh/​docket/​review/​docket156/​default.html.

Public Comment Period: Comments must be received by March 15, 2011.

A public meeting to be convened either in Cincinnati, Ohio or via Teleweb may be scheduled at a date and time to be announced later if determined to be necessary. This public meeting will be announced via a subsequent notice.


Written comments, identified by docket number NIOSH-156, may be submitted by any of the following ways:

  • Mail: NIOSH Docket Office, Robert A. Taft Laboratories, MS-C34, 4676 Columbia Parkway, Cincinnati, OH 45226.
  • Facsimile: (513) 533-8285.
  • E-mail:

All information received in response to this notice will be available for public examination and copying at the NIOSH Docket Office, 4676 Columbia Parkway, Room 111, Cincinnati, Ohio 45226. A complete electronic docket containing all comments submitted will be available on the NIOSH Web page at​niosh/​docket, and comments will be available in writing by request. NIOSH includes all comments received without change in the docket, including any personal information provided. All electronic comments should be formatted as Microsoft Word. Please make reference to docket number NIOSH 156.

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G. Scott Dotson, NIOSH, Robert A. Taft Laboratories, MS-C32, 4676 Columbia Parkway, Cincinnati, OH 45226, telephone (513) 533-8540.

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In 1974, the National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) jointly initiated the development of occupational health standards consistent with Section 6(b) of the Occupational Safety and Health Act of 1970 for substances with then-existing OSHA permissible exposure limits (PELs). This joint effort was called the Standards Completion Program (SCP). As part of the respirator selection process for each draft technical standard, Immediately Dangerous to Life and Health (IDLH) values were determined for each chemical. The purpose of deriving an IDLH value was to provide guidance on respirator selection and to establish a maximum exposure concentration in Start Printed Page 4116which workers, in the event of respiratory protection failure (e.g., contaminant breakthrough in a cartridge respirator or stoppage of air flow in a supplied-air respirator), could escape safely when the exposure was below the IDLH value.

Since the establishment of the original IDLH values in 1974, NIOSH has continued to review the available scientific data to improve the protocol used to derive the acute exposure guidelines, in addition to the chemical-specific IDLH values. This draft CIB represents the most recent update of the scientific rationale and process used to derive IDLH values based on health effects considerations determined through a critical assessment of the toxicology and human health effects data.

The new process relies on a weight-of-evidence approach based on scientific judgment for establishing IDLH values that allows for the critical evaluation of the quality and consistency of the scientific data, and in extrapolation from the available data to the IDLH value. The weight-of-evidence approach refers to the critical examination of all the available data from diverse lines of evidence and the derivation of a scientific interpretation based on the collective body of data including its relevance, quality and reported results. Guidelines are presented to aid in the selection of the critical adverse effect, a point of departure (POD) or the point on the dose-response curve from which dose extrapolation is initiated, and applying default uncertainty factors (UFs) to derive the IDLH value. Conceptually, the derivation process presented in this CIB is similar to that used in other risk assessment applications including the process steps of:

  • Hazard characterization,
  • Identification of critical adverse effects,
  • Identification of a POD,
  • Application of an appropriate UF based on the study and POD, and
  • Determination of the final risk value.

Supplemental information included within this draft CIB includes (1) An overview of the literature search strategy used to identify relevant data, (2) the scheme used to prioritize and select chemicals for which an IDLH value will be established and (3) an overview of the analysis applied by NIOSH to develop a scientifically-based approach for the selection of the UF during the derivation of IDLH values. In addition, Appendix A of the draft CIB presents an example of the derivation of an IDLH value for vinyl acetate (CAS #108-50-4) based on the new process.

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Dated: January 13, 2011.

John Howard,

Director, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention.

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[FR Doc. 2011-1301 Filed 1-21-11; 8:45 am]