The NRC convened the Committee on Acute Exposure Guideline Levels to review the AEGL documents approved by NAC. The committee members were selected for their expertise in toxicology; medicine, including pharmacology and pathology; industrial hygiene; biostatistics; and risk assessment.
The charge to the committee is to (1) review the proposed AEGLs for scientific validity, completeness, internal consistency, and conformance to the NRC (1993) guidelines report; (2) review NAC’s research recommendations and—when appropriate—identify additional priorities for research to fill data gaps; and (3) review periodically the recommended standard procedures for developing AEGLs.
This interim report presents the committee’s conclusions and recommendations for improving the following AEGL technical support documents (TSDs): acrylonitrile, allyl alcohol, epichlorohydrin, ethylene chlorohydrin, ethyl phosphorodichloridate, hexane, ketene, lewisite, mercaptans (ethyl mercaptan, methyl mercaptan, phenyl mercaptan, and tert-ocyl mercaptan), methanesulfonyl chloride, methyl isothiocyanate, monoisocyanates (n-butyl isocyanate, cyclohexyl isocyanate, ethyl isocyanate, and phenyl isocyanate), nitric acid, 3-quinuclidinyl benzilate, tear gas, titanium tetrachloride, trimethylacetyl chloride, and vinyl acetate monomer. These documents were reviewed by the committee at a meeting on May 2-4, 2012.
Sources for General Information
TSDs often cite references that are periodically updated (e.g., Patty’s Industrial Hygiene, Merck Index), particularly in reference to chemical and physical properties. The most recent editions of these references should be used as much as possible to ensure that the most current information is being provided. Sometimes material in an earlier edition is revised in a later edition. In addition, information from common secondary sources should be verified by reviewing the primary references; if more current versions of the primary references are available, those newer references should be consulted for the most current information.
Extant Standards and Guidelines
The section in the TSDs on Extant Standards and Guidelines should provide substantive discussion of the comparison of AEGLs values and other relevant guidelines (see NRC 2001). Simple side-by-side comparisons of values are not adequate. It is particularly important to provide substantive context when there are substantial differences between the values. The discussion should examine possible reasons for the differences, such as (1) the documented quantitative derivation process for AEGLs compared with the processes used by other organizations, (2) different data requirements for the guidelines, (3) different target populations, (4) duration of exposure, (5) end point of concern (immediate vs delayed effects), and (6) other considerations. For example, occupational guidelines are intended to protect the working adult population from adverse effects from exposure to a chemical over a working lifetime, whereas AEGL values are intended to protect the general population (including sensitive subpopulations) from adverse effects from a one-time exposure to the chemical.
Because standards and guidelines are periodically updated, it is important that the most recent publication or listing of standards for each organization be consulted and referenced to document that the standard is still current. The discussion of the values should note the date the guideline was issued to provide historical context, and also reference the supporting (probably older) documentation of the standard.
Footnotes to the table on Extant Standards and Guidelines should indicate that ACGIH®, TLV®, AIHA®, and possibly other terms are registered trademarks.