In 1991, the Environmental Protection Agency (EPA) and the
Agency for Toxic Substances and Disease Registry (ATSDR) asked
the National Research Council (NRC) to provide technical
guidance for establishing community emergency exposure levels
for extremely hazardous substances (EHSs) pursuant to the
Superfund Amendments and Reauthorization Act of 1986. In
response to that request, the NRC published Guidelines for
Developing Community Emergency Exposure Levels for Hazardous
Substances in 1993. Subsequently, Standing Operating Procedures
for Developing Acute Exposure Guideline Levels for Hazardous
Substances was published in 2001; it provided updated
procedures, methods, and other guidelines used by the National
Advisory Committee (NAC) on Acute Exposure Guideline Levels
(AEGLs) for hazardous substances for assessing acute adverse
health effects. Using both these reports, the NAC--consisting of
members from the EPA, the Department of Defense (DOD), the
Department of Energy (DOE), the Department of Transportation