Title : Nervous system effects in chemicals with immediately dangerous to life or health values
Abstract:
Introduction: Immediately Dangerous to Life or Health (IDLH) values are intended to characterize the risk associated with acute inhalational exposures in the workplace. A main goal of IDLH values is to ensure that a worker can escape from a contaminated environment in the event of failure of protective equipment and to indicate a maximum level above which only a highly reliable breathing apparatus, providing maximum protection, is permitted (Current Intelligence Bulletin 66: Derivation of Immediately Dangerous to Life or Health (IDLH) Values). The purpose of this initial analysis is to examine chemicals with IDLH values and nervous system effects.
Methods: This initial exploratory analysis examined 384 chemicals with previously established IDLH values based on animal and human data, available on the National Institute for Occupational Safety and Health (NIOSH) website at Immediately Dangerous to Life or Health | NIOSH | CDC. IDLH information was compiled using web scraping and keyword-based text mining methods. In parsing these data, three sections of each page were searched: Basis for original (SCP) IDLH, Human data, and Basis for revised IDLH (where present). The text of those sections was matched case-insensitively against a list of 29 predefined neurological endpoint terms of consciousness, unconsciousness, intoxication, light-headedness, dizziness, confusion, disorientation, nausea, vomiting, headache, tremor, convulsion, seizure, coma, neurotoxic, cholinesterase, narcosis, narcotic, anesthetic, central nervous system, CNS, paresthesia, ataxia, tyrosine hydroxylase, 5-hydroxytryptamine, histamine receptor, gamma-aminobutyric acid, GABA, and glutamate.
Results: Among 384 chemicals with IDLH values examined, 95 were associated with neurological endpoint terms. Of these, 64 were organic compounds containing only carbon, hydrogen, and oxygen. Nitrogen-containing (n=9), metal oxide (n=6), and sulfur-containing compounds (n=5) were also present. The predominant types of neurological symptoms found were headache (N=31 chemicals), nausea (N=30), and dizziness (N=19), with 23 chemicals associated with more than one of these. Other neurological signs and symptoms found included light-headedness, dizziness, tremor, intoxication, narcosis, loss of consciousness and convulsions. Human and animal data provided neurological information for different chemicals.
Conclusion/Discussion: Among the 384 chemicals with IDLH values examined, 95 had associations with nervous system effects, predominantly with nausea and headache. Other neurological findings occurred in animal model and human studies. Symptoms such as headache must be interpreted cautiously for acute occupational exposures. Future work will explore IDLH values based on neurological versus respiratory signs and symptoms. The association between neurological signs and symptoms and acute occupational exposure contexts and physiochemical properties will also be evaluated. The present characterization is an important initial step for further development of IDLH values and for consideration of risk management strategies to mitigate acute occupational exposures to chemicals that may have associations with neurological signs and symptoms.
The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. Throughout this work, the authors used Github Copilot (Claude Sonnet 4.6) to assist with generating, debugging, or editing analytic code. The authors reviewed, tested, and validated all code.
