SUPPLEMENTARY INFORMATION:

In 2013, NIOSH published Current Intelligence Bulletin (CIB) 66—Derivation of Immediately Dangerous to Life or Health (IDLH) Values [ http://www.cdc.gov/​niosh/​docs/​2014-100/​pdfs/​2014-100.pdf] [NIOSH 2013]. The information presented in this CIB represents the most recent update of the scientific rationale and the methodology (hereby referred to as the IDLH methodology) used to derive IDLH values. Since the establishment of the IDLH values in the 1970s, NIOSH has continued to review available scientific data to improve the protocol used to derive acute exposure guidelines, in addition to the chemical-specific IDLH values.

IDLH values are based on health effects considerations determined through a critical assessment of the toxicology and human health effects data. This approach ensures that the IDLH values reflect an airborne concentration of a substance that represents a high-risk situation that may endanger workers' lives or health.

The primary steps applied in the establishment of an IDLH value include the following:

1. Critical review of human and animal toxicity data to identify potentially relevant studies and characterize the various lines of evidence that can support the derivation of the IDLH value;

2. Determination of a chemical's mode of action (MOA) or description of how a chemical exerts its toxic effects;

3. Application of duration adjustments (time scaling) to determine 30-minute-equivalent exposure concentrations and the conduct of other dosimetry adjustments, as needed;

4. Experimental or other data to establish a point of departure (POD) such as lethal concentrations ( e.g., LC50), lowest observed adverse effect level (LOAEL), or no observed adverse effect level (NOAEL);

5. Selection and application of an uncertainty factor (UF) for POD or critical adverse effect concentration, identified from the available studies to account for issues associated with interspecies and intraspecies differences, severity of the observed effects, data quality, or data insufficiencies; and

6. Development of the final recommendation for the IDLH value from the various alternative lines of evidence, with use of a weight-of-evidence approach to all of the data.

NIOSH seeks to obtain materials, including published and unpublished reports and research findings, to evaluate the possible acute health risks of occupational exposure to the following six chemicals:

1. Allyl Alcohol (CAS# 107-18-6)

2. Bromine Chloride (CAS# 13863-41-7)

3. Hydrogen Bromide (CAS# 10035-10-6)

4. Hydrogen Iodide (CAS# 10034-85-2)

5. Lewisite (a chemical warfare agent) (CAS#s 541-25-3, 40334-69-8, 40334-70-1)

6. Propylene Imine (CAS# 75-55-8)

Materials also include reports of acute animal toxicity studies, acute human toxicology studies, mode of action studies, and other information about a chemical's toxic effects such as 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. ( printed page 61058)

In a subsequent notice, Draft IDLH Value profiles for these chemicals will be made available for public comment.

Reference

NIOSH [2013]. Current intelligence bulletin 66: derivation of immediately dangerous to life or health (IDLH) values. Cincinnati, OH: US Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 2014-100.