U.S. NIOSH Seeks Input on Developing IDLH Values for Six Chemicals

Posted on: November 18, 2019

by Caroline Miller, CIH, CSP

picture of testtubes and a dropper - Learn more about NioshOn November 12, 2019, in a Federal Register notice, the National Institute for Occupational Safety and Health (NIOSH) has invited the public to provide input on developing Immediately Dangerous to Life or Health (IDLH) Value for six chemicals.

The input will be used to develop IDLH Value Profile documents based on the Current Intelligence Bulletin (CIB) 66 – Derivation of Immediately Dangerous to Life or Health (IDLH) Values, published in 2013.  The CIB represents the most recent update of the scientific rationale and protocol used to derive IDLH Values.  The rationale and protocol is based on health effects considerations determined through a critical assessment of the toxicology and human health effects data.

Guidelines presented in the CIB aid in selecting the critical adverse effect, the point of departure (POD), or the point on the dose-response curve from which dose extrapolation is initiated, and applying default uncertainty factors (UFs)  in order to derive the IDLH value. The methods presented in the CIB are comparable to those used in other risk assessment applications incorporating the following process steps:

  • 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.

The six affected chemicals that are being considered for IDLH value development are as follows:

  • Allyl Alcohol (CAS# 107–18–6)
  • Bromine Chloride (CAS# 13863–41–7)
  • Hydrogen Bromide (CAS# 10035–10–6)
  • Hydrogen Iodide (CAS# 10034–85–2)
  • Lewisite (chemical warfare agent) (CAS#s 541–25–3, 40334–69–8, 40334–70–1)
  • Propylene Imine (CAS# 75–55–8)

NIOSH would like to collect published and unpublished information in order to propose IDLH values for the six chemicals in accordance with the CIB.  The information NIOSH is seeking includes toxicology studies, irritation effects, nervous system effects, toxicants, gastrointestinal effects, cardiovascular changes, and asphyxiants.  NIOSH will publish Draft IDLH Values Profiles for the chemicals in a future Federal Register notice for public comment.

The public has until January 13, 2020 to provide electronic or written comments at or by mail.


Recommended Action Items:

  • Review your inventory of substances to determine if your company uses any of the affected chemicals
  • Review your standard operating procedures and workplace practices to ensure that employees can escape should an IDLH atmosphere develop



Request for Information for Six Chemicals To Develop Immediately Dangerous to Life or Health (IDLH) Values:



NIOSH, IDLH, public comment

Want to know more?

A list of current IDLH values, as well as other NIOSH lists, can be found in UL’s LOLI database.

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