Derivation of temporary emergency exposure limits (TEELs)

Abstract

Short-term chemical concentration limits are used in a variety of applications, including emergency planning and response, hazard assessment and safety analysis. Development of emergency response planning guidelines (ERPGs) and acute exposure guidance levels (AEGLs) are predicated on this need. Unfortunately, the development of peer-reviewed community exposure limits for emergency planning cannot be done rapidly (relatively few ERPGs or AEGLs are published each year). To be protective of Department of Energy (DOE) workers, on-site personnel and the adjacent general public, the DOE Subcommittee on Consequence Assessment and Protective Actions (SCAPA) has developed a methodology for deriving temporary emergency exposure limits (TEELs) to serve 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 used only hierarchies of published concentration limits (e.g. PEL-or TLV-TWAs, -STELs or -Cs, and IDLHs) to provide estimated values approximating ERPGs. Published toxicity data (e.g. lc 50 , lc LO , ld 50 and ld LO for TEEL-3, and tc LO and td LO for TEEL-2) are included in the expanded method for deriving TEELs presented in this paper. The addition here of published toxicity data (in addition to the exposure limit hierarchy) enables TEELs to be developed for a much wider range of chemicals than before. Hierarchy-based values take precedence over toxicity-based values, and human toxicity data are used 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 community exposure limits for over 1200 chemicals to date. The new TEEL methodology enables emergency planners to develop useful approximations to peer-reviewed community exposure limits (such as the ERPGs) with a high degree of confidence. For definitions and acronyms, see Appendix.

Emergency Exposure Limits for toxic chemicals in Major hazard installations of China

“…The TEEL methodology was originally based on hierarchies of commonly available published and documented concentration-limit parameters [8]. Now, the hierarchy of sources for deriving TEEL is shown in Table 1 [9].…”

Proposed Occupational Exposure Limits for Non-Carcinogenic Hanford Waste Tank Vapor Chemicals

“…These TEELs are assigned to chemicals on a temporary basis until they can be replaced with AEGLs or emergency response planning guidelines, which require additional documentation and assessment. The protocol used to consider available OEL and toxicological data in the development of TEELs has been published (Craig et al 2000). Four levels of TEELs (TEEL-0, TEEL-1, TEEL-2, TEEL-3) are calculated as fractions based on set criteria.…”

Assessing the application of acute toxic gas standards

“…Iyoho et al 2009). Temporary Emergency Exposure Limits (TEELs), developed by the U.S. Department of Energy (DOE), are used to approximate ERPGs until peer-reviewed, toxicology-based ERPGs, AEGLs, or equivalents are determined (Craig et al, 2000), and thus assume the population of the utilized standard. The International Organization for Standardization (ISO 13571) has developed a toxic risk assessment model for an average, healthy person, requiring the user to add his own safety factors (ISO 13571, 2007).…”

“…To this end, many risk assessment models have been developed, along with safety standards that regulate and guide decision-making for toxic gas exposure (AIHA, 2009;CHPPM, 2002;Craig et al, 2000;Ng et al, 2007;NIOSH, 1994;NIOSH, 2006;NRC, 2001;Osha, 1992;Purser, 2008;Speitel, 1995;Stuhmiller et al, 2006). Gas toxicity standards, developed to protect certain populations, are typically expressed as exposure concentrations and durations that should not be exceeded to avoid certain health effects.…”