Derivation of temporary emergency exposure limits (TEELs)

Short-term chemical concentration limits are used in a variety of applicati ons, including emergency planning and response, hazard assessment and safet y analysis. Development of emergency response planning guidelines (ERPGs) a nd acute exposure guidance levels (AEGLs) are predicated on this need. Unfo rtunately, the development of peer-reviewed community exposure limits for e mergency planning cannot be done rapidly (relatively few ERPGs or AEGLs are published each year). To be protective of Department of Energy (DOE) worke rs, on-site personnel and the adjacent general public, the DOE Subcommittee on Consequence Assessment and Protective Actions (SCAPA) has developed a m ethodology for deriving temporary emergency exposure limits (TEELs) to serv e as temporary guidance until ERPGs or AEGLs can be developed. These TEELs are approximations to ERPGs to be used until peer-reviewed toxicology-based ERPGs, AEGL or equivalents can be developed. Originally, the TEEL method u sed only hierarchies of published concentration limits (e.g. PEL- or TLV-TW As, -STELs or -Cs, and IDLHs) to provide estimated values approximating ERP Gs, Published toxicity data (e.g. LC50, LCLO, LD50 and LDLO for TEEL-3, and TCLO and TDLO for TEEL-2) are included in the expanded method for deriving TEELs presented in this paper. The addition here of published toxicity dat a (in addition to the exposure limit hierarchy) enables TEELs to be develop ed for a much wider range of chemicals than before. Hierarchy-based values take precedence over toxicity-based values, and human toxicity data are use d in preference to animal toxicity data. Subsequently, default assumptions based on statistical correlations of ERPGs at different levels (e.g. ratios of ERPG-3s to ERPG-2s) are used to calculate TEELs where there are gaps in the data. Most required input data are available in the literature and on CD ROMs, so the required TEELs for a new chemical can be developed quickly. The new TEEL hierarchy/toxicity methodology has been used to develop commu nity exposure limits for over 1200 chemicals to date. The new TEEL methodol ogy enables emergency planners to develop useful approximations to peer-rev iewed community exposure limits (such as the ERPGs) with a high degree of c onfidence. For definitions and acronyms, see Appendix. Copyright (C) 2000 W estinghouse Safety Management Solutions LLC obtained pursuant to US governm ent contract.