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Request for information for 6 chemicals to develop Immediately Dangerous to Life or Health (IDLH) Values

October 2019
NIOSH Docket Number 156-E, CDC-2019-0093

The National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC) is evaluating the scientific data for 6 chemicals, allyl alcohol, bromine chloride, hydrogen bromide, hydrogen iodide, lewisite, and propylene imine, to develop new or updated Immediately Dangerous to Life or Health (IDLH) values.  The current IDLH values for these chemicals are listed below (if available).

IDLH values
Chemical Name Current IDLH Value
Allyl alcohol 20 parts per million (ppm)
Bromine chloride Not available
Hydrogen bromide 30 ppm
Hydrogen iodide Not available
Lewisite Not available
Propylene imine 100 ppm

In November 2019, NIOSH Published a request for information to support the development of IDLH values for these chemicals. (See the link to the Federal Register Notice in the Reference Documents section below.) NIOSH sought to obtain materials, including published and unpublished reports and research findings, to evaluate the possible acute health risks of occupational exposure to these chemicals. This information included reports of acute animal toxicity studies, acute human toxicology studies, mode of action studies, and other information about a chemical’s toxic effects. NIOSH also sought studies on sensory or respiratory irritation, nervous system effects (e.g., dizziness, central nervous system excitability, autonomic effects, muscle tone/equilibrium effects, sensorimotor reactivity, nervous system histopathology), metabolic toxicants, target organ toxicants, gastrointestinal effects, cardiovascular changes, and asphyxiants. The period to submit comments ended January 13 2020.

In June 2023, NIOSH published a Federal Register notice requests public comment and technical review on two (2) draft Immediately Dangerous to Life or Health (IDLH) Value Profiles regarding the chemical’s hydrogen bromide (CAS# 10035–10–6) and hydrogen iodide (CAS# 10034–85– 2). The period to submit comments ended August 21,2023. NIOSH did not receive any public comments.

NIOSH will publish IDLH Value profiles for these chemicals which will provide detailed summaries of the health hazards of acute exposures to high airborne concentrations and the rationale for the IDLH value. Draft IDLH Value profiles will be made available for public comment.

To view the notice and related materials, visit  and enter CDC-2019-0093 in the search field and click “Search.”

Reference Documents