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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.
... TEELs are used in similar situations as the 60-minute AEGLs and ERPGs. 9 A hazardous chemical may have up to three TEEL values, each of which corresponds to a specific step in health effects. These three TEEL steps are defined as follows: ...
... 3. TEEL-1 is the airborne concentration of a hazardous chemical above which it is predicted that the general population could experience notable discomfort, irritation, or certain asymptomatic, and non-sensory effects when exposed for more than 1 h. 9 The present paper was conducted with three different scenarios as follows: ...
One of the substances with high potential to cause damage that is used widely in chemical plants is liquefied petroleum gas (LPG). The aim of the present study is to model the consequences of leakage from a storage tank containing LPG using different scenarios. ALOHA software was used as one of the best modeling programs for identification of emergency responses required at the time of the gas leakage based on modeling results. According to ALOHA program modeling results, the area called TEEL‐3 was located within a distance of 187 m from the tank, and the threat to people in this area was determined. In case of LPG leakage from the storage tank, the concentration of LPG was about 2100 ppm which is equal to the lower explosive limit at the distance of 187 m. The consequences of combustion and explosion of LPG gas at a distance of 65 m from the storage tank were the most serious danger that threatens humans. This paper has an important role in modeling the harmful effects of the release of LPG and hazardous substances in different scenarios.
... AEGLs provide limit values for each level at a range of averaging periods: 10-min, 30-min, 1-hour, 4-hour and 8-hour. ERPGs offer a single standard for 1-hour (Craig et al., 2000;Blakey et al., 2013;Rusch, 2016). However as emergency standards, AEGLs and ERPGs do not provide an equivalent indication of impact on health, this being due to differences in how each has weighted the epidemiological evidence on which the standards are based (Cavender et al., 2008;Ö berg et al., 2010;Johansson et al., 2016). ...
We report on the concentration ranges and combustion source-related emission profiles of organic and inorganic species released during 34 major industrial fires in the UK. These episodic events tend to be acute in nature and demand a rapid public health risk assessment to indicate the likely impact on exposed populations. The objective of this paper is to improve our understanding of the nature, composition and potential health impacts of emissions from major incident fires and so support the risk assessment process. Real world monitoring data was obtained from portable Fourier Transform Infrared (FTIR) monitoring (Gasmet DX-4030/40) carried out as part of the UK’s Air Quality in Major Incidents service. The measured substances include carbon monoxide, sulphur dioxide, nitrogen dioxide, ammonia, hydrogen chloride, hydrogen bromide, hydrogen fluoride, hydrogen cyanide, formaldehyde, 1,3-butadiene, benzene, toluene, xylenes, ethyl benzene, acrolein, phosgene, arsine, phosphine and methyl isocyanate. We evaluate the reported concentrations against Acute Exposure Guideline Values (AEGLs) and Emergency Response Planning Guidelines (ERPGs), as well as against UK, EU and WHO short-term ambient guideline values. Most exceedances of AEGL or ERPG guideline values were at levels likely only to cause discomfort to exposed populations (hydrogen cyanide, hydrogen chloride, hydrogen fluoride and formaldehyde), though for several substances the exceedances could have potentially given rise to more serious health effects (acrolein, phosphine, phosgene and methyl isocyanate). In the latter cases, the observed high concentrations are likely to be due to cross-interference from other substances that absorb in the mid-range of the infrared spectrum, particularly when the ground level plume is very concentrated.
... This approach is incorporated in the derivation of some temporary emergency exposure limits (TEELs). 26 Recovery phase-During the recovery phase, the active release of the chemical is stabilized or controlled. Thus, the emergency situation evolves to more closely resemble the characteristics of traditional workplace exposures. ...
Effective emergency management and response require appropriate utilization of various resources as an incident evolves. This manuscript describes the information resources used in chemical emergency management and operations and how their utility evolves from the initial response phase to recovery to event close out. The authors address chemical hazard guidance in the context of four different phases of emergency response: preparedness, emergency response (both initial and ongoing), recovery, and mitigation. Immediately following a chemical incident, during the initial response, responders often use readily available, broad-spectrum guidance to make rapid decisions in the face of uncertainties regarding potential exposure to physical and health hazards. Physical hazards are described as the hazards caused by chemicals that can cause harm with or without direct contact. Examples of physical hazards include explosives, flammables, and gases under pressure. This first line of resources may not be chemical-specific in nature, but it can provide guidance related to isolation distances, protective actions, and the most important physical and health threats. During the ongoing response phase, an array of resources can provide detailed information on physical and health hazards related to specific chemicals of concern. Consequently, risk management and mitigation actions evolve as well. When the incident stabilizes to a recovery phase, the types of information resources that facilitate safe and effective incident management evolve. Health and physical concerns transition from acute toxicity and immediate hazards to both immediate and latent health effects. Finally, the information inputs utilized during the preparedness phase include response evaluations of past events, emergency preparedness planning, and chemical-specific guidance about chemicals present. This manuscript details a framework for identifying the effective use of information resources at each phase and provides case study examples from chemical hazard emergencies.
... LC 50 data generated from these tests are used to categorize and rank test substances based on lethality, often with little or no elucidation of the site or underlying mechanism of toxicity. Other acute assessment derivations currently based on in vivo data consider exposure durations spanning a range from 10-minutes to 24 hours, designate various non-lethal severity categories, and consider clinical measures or endpoints (e.g., developmental, reproductive) in addition to LC 50 values (Rusch 1993;Vincent 1995;Craig, Davis et al. 2000;Krewski, Bakshi et al. 2004). Developing non-animal approaches that leverage pathway-based mechanistic information will not only provide a predictive tool for establishing potential hazard, but will likely provide more information to the risk assessor than an LC 50 or other in vivo observations. ...
New approaches are needed to assess the effects of inhaled substances on human health. These approaches will be based on mechanisms of toxicity, an understanding of dosimetry, and the use of in silico modeling and in vitro test methods. In order to accelerate wider implementation of such approaches, development of adverse outcome pathways (AOPs) can help identify and address gaps in our understanding of relevant parameters for model input and mechanisms, and optimize non-animal approaches that can be used to investigate key events of toxicity. This paper describes the AOPs and the toolbox of in vitro and in silico models that can be used to assess the key events leading to toxicity following inhalation exposure. Because the optimal testing strategy will vary depending on the substance of interest, here we present a decision tree approach to identify an appropriate non-animal integrated testing strategy that incorporates consideration of a substance's physicochemical properties, relevant mechanisms of toxicity, and available in silico models and in vitro test methods. This decision tree can facilitate standardization of the testing approaches. Case study examples are presented to provide a basis for proof-of-concept testing to illustrate the utility of non-animal approaches to inform hazard identification and risk assessment of humans exposed to inhaled substances.
... Finally, note that the DDC method is applicable to acute exposures: therefore it employs the indices mentioned in this section as a platform, incorporating the exposure characteristics described in the technical reports that justify these values (Craig et al., 2000;ERPG and WEEL, 2007;US EPA, 2012a). ...
... The method estimates maximum and minimum levels (hereinafter referred to as maximum damage and minimum damage, respectively) of adverse health effects caused by the exposure to a toxic cloud, using a recursive algorithm for that purpose (Sanchez, 2012;Sanchez et al., 20102012a,b). DDC is applicable to acute exposures: therefore it employs the toxicological indices of acute exposure (AEGLs, ERPGs and TEELs), incorporating the exposure characteristics described in the technical reports that justify these values (Craig et al., 2000;ERPG and WEEL, 2007;US EPA, 2012). As described in Sanchez et al. (2013), the toxicological indices (AEGLs, ERPGs and TEELs) are comparable in terms of levels of adverse health effects; therefore we shall denote different levels of the indices of reference with the acronym HEL (Health Effects Level); for example, AEGL 1 corresponds to HEL 1. DDC applies a methodology of differential analysis which ensures that the expected effect on health is among the maximum and minimum damage mentioned. ...
Information on spatial and time dependent concentration patterns of
hazardous substances, as well as on the potential effects on population,
is necessary to assist in chemical emergency planning and response. To
that end, some models predict transport and dispersion of hazardous
substances, and others estimate potential effects upon exposed
population. Taken together, both groups constitute a powerful tool to
estimate vulnerable regions and to evaluate environmental impact upon
affected populations.
... Finally, note that the DDC method is applicable to acute exposures: therefore it employs the indices mentioned in this section as a platform, incorporating the exposure characteristics described in the technical reports that justify these values (Craig et al., 2000;ERPG and WEEL, 2007;US EPA, 2012a). ...
The adverse health effects of the release of hazardous substances into the atmosphere continue being a matter of concern, especially in densely populated urban regions. Emergency responders need to have estimates of these adverse health effects in the local population to aid planning, emergency response, and recovery efforts. For this purpose, models that predict the transport and dispersion of hazardous materials are as necessary as those that estimate the adverse health effects in the population.In this paper, we present the results obtained by coupling a Computational Fluid Dynamics model, FLACS (FLame ACceleration Simulator), with an exposure model, DDC (Damage Differential Coupling). This coupled model system is applied to a scenario of hypothetical release of chlorine with obstacles, such as buildings, and the results show how it is capable of predicting the atmospheric dispersion of hazardous chemicals, and the adverse health effects in the exposed population, to support decision makers both in charge of emergency planning and in charge of real-time response.The results obtained show how knowing the influence of obstacles in the trajectory of the toxic cloud and in the diffusion of the pollutants transported, and obtaining dynamic information of the potentially affected population and of associated symptoms, contribute to improve the planning of the protection and response measures.
... 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. ...
A large number of volatile chemicals have been identified in the headspaces of tanks used to store mixed chemical and radioactive waste at the U.S. Department of Energy (DOE) Hanford Site, and there is concern that vapor releases from the tanks may be hazardous to workers. Contractually established occupational exposure limits (OELs) established by the Occupational Safety and Health Administration (OSHA) and American Conference of Governmental Industrial Hygienists (ACGIH) do not exist for all chemicals of interest. To address the need for worker exposure guidelines for those chemicals that lack OSHA or ACGIH OELs, a procedure for assigning Acceptable Occupational Exposure Limits (AOELs) for Hanford Site tank farm workers has been developed and applied to a selected group of 57 headspace chemicals.
... The two most frequently used values are Acute Exposure Guideline Levels (AEGL) [7][8][9] developed by the U.S. National Advisory Committee for the Development of Acute Exposure Guideline Levels for Hazardous Substances (AEGL Committee), which is managed by U.S. Environmental Protection Agency (U.S. EPA), and Emergency Response Planning Guidelines (ERPG) [10] developed by the American Industrial Hygiene Association (AIHA). Other values include Temporary Emergency Exposure Limit (TEEL) [11][12][13] values developed by Subcommittee on Consequence Assessment and Protective Actions (SCAPA) and Immediately Dangerous to Life and Health limit (IDLH) [14] values defined by the U.S. National Institute of Occupational Safety and Health (NIOSH). In addition, there are national values available in some European countries, for example in the Netherlands (Intervention Values for Dangerous Substances) [15] and France (SEI and SEL; Threshold of Lethal Effects and Threshold of Irreversible Effects) [16]. ...
A scientifically sound assessment of the risk to human health resulting from acute chemical releases is the cornerstone for chemical incident prevention, preparedness and response. Although the general methodology to identify acute toxicity of chemicals has not substantially changed in the last decades, there is ongoing debate on the current approaches for human health risk assessment in scenarios involving acute chemical releases. A survey was conducted to identify: (1) the most important present and potential future chemical incident scenarios and anticipated changes in chemical incidents or their management; (2) information, tools and guidance used in different countries to assess health risks from acute chemical releases; and (3) needs for new information, tools, guidance and expertise to enable the valid and rapid health risk assessment of acute chemical exposures. According to the results, there is an obvious variability in risk assessment practices within Europe. The multiplicity of acute exposure reference values appears to result in variable practices. There is a need for training especially on the practical application of acute exposure reference values. Although acutely toxic and irritating/corrosive chemicals will remain serious risks also in future the development of plausible scenarios for potential emerging risks is also needed. This includes risks from new mixtures and chemicals (e.g. nanoparticles).
... The French land-use planning criterion applied in 1990s adopted LC1 (lethal concentration which causes mortality of 1% of the exposed population) to identify the hazard zone corresponding to the beginning of irreversible heath effects and Immediately Dangerous to Life and Health limit (IDLH) as the threshold concentration to identify the hazard zone where the lethal effect occurs [5,6]. Besides LC1 and IDLH, some other databases for toxic effects were used: Acute Exposure Guideline Levels (AEGL), Emergency Response Planning Guideline (ERPG), Temporary Emergency Exposure Limit (TEEL), Acute Exposure Threshold Levels (AETL) [8][9][10][11][12][13][14][15]. The standards on acceptable or tolerable risks are usually based on the risk statistics as well as the economy development level and the public value concept. ...
A case study on the safety distance assessment of a chemical industry park in Shanghai, China, is presented in this paper. Toxic releases were taken into consideration. A safety criterion based on frequency and consequence of major hazard accidents was set up for consequence analysis. The exposure limits for the accidents with the frequency of more than 10(-4), 10(-5)-10(-4) and 10(-6)-10(-5) per year were mortalities of 1% (or SLOT), 50% (SLOD) and 75% (twice of SLOD) respectively. Accidents with the frequency of less than 10(-6) per year were considered incredible and ignored in the consequence analysis. Taking the safety distance of all the hazard installations in a chemical plant into consideration, the results based on the new criterion were almost smaller than those based on LC50 or SLOD. The combination of the consequence and risk based results indicated that the hazard installations in two of the chemical plants may be dangerous to the protection targets and measurements had to be taken to reduce the risk. The case study showed that taking account of the frequency of occurrence in the consequence analysis would give more feasible safety distances for major hazard accidents and the results were more comparable to those calculated by risk assessment.
Decontamination and Treatment of Injured Persons during Chemical Agent Incidents
Domres, Bernd; Manger, Andreas; Brockmann, Stefan; Wenke, Rainer
Introduction: The conception of a Medical incident response plan for the treatment of injured persons who have been contaminated during a chemical incident challenges more than one of the rescue services involved in civil emergency response. Our main objective in this project was the creation of an incident management plan compatible with existing rescue service logistics and resources that can be quickly and efficiently activated at a local level.
Methods: Under the supervision of the Schutzkommission des Inneren and together with delegates from EMS, fire, technical rescue services and the German army a consensus conferences to investigate the general conditions necessary and the existing structure available for managing victims of chemical incidents, was created. Research of existing literature, and an analysis of past incidents lead to the development of this concept. Typical injury patterns and their treatment in respect to decontamination procedures were considered, the necessary structure for casualty treatment and decontamination areas were then derived and commercially available products were tested for their usefulness in this situation. Standard operating procedures and algorithms were developed to aid realization of the concept. The suitability of the personal protective equipment and the question, if under these conditions the procedures of Advanced Life Support can be performed, was evaluated in a standardized simulator model. The necessary training for rescue personnel involved was defined. To validate the concept, an exercise was carried out.
Results: All persons present at a chemical incident are to be classified as being contaminated. Injured persons must be separated into triage categories, and life threatening conditions treated before being decontaminated. Decontamination at the incident scene is necessary to prevent the transportation of the contaminant away from the incident scene. The principles of the Decontamination of injured persons are based on the following pillars: Triage, early removal of clothing, Management of personal belongings and valuables, Basic Life Support, Spot Decontamination, management and sealing of open wounds, application of antidotes, and primary decontamination of ambulant and non-ambulant victims.
The co-operation and the definition of roles between fire service (deconta- mination) and Emergency Medical Services (triage and treatment) is necessary.
The concept uses existing decontamination vehicles used for the decontamination of fire fighters, by expanding it inventory with medical equipment, and extra technical apparatus. Using a modular approach, the system can be easily added to by further units to treat multiple numbers of victims. However, demands on all rescue services involved are high, and must be complimented with an equally high standard of training, especially where rescue services have to learn skills not akin to their standard duties. An implementation of the system covering all geographical areas with specialized units is not possible, therefore a risk analysis to optimally position limited resources has to be conducted. The different structures of disaster services in the individual states of Germany cannot compromise the implication and realization of this concept. Legislative bodies must strive to allow for an uncomplicated integration and disposition of disaster management resources. The development of this concept showed that there are many similarities between the management of incidents with biological, nuclear, and chemical contaminants, but it is important to differentiate between the three, and separate concepts have to be developed to facilitate optimal preparedness and management of such events.
A critical factor is the response time of rescue services. The problem of providing adequate oxygen supplies and ventilation for the treatment of multiple patients with breathing disorders due to intoxication has to be solved. A sufficient method of measuring contamination of individual victims is still not possible. A further aspect to be tackled is the hospital management of such incidents, as a majority of victims will most probably bypass the primary decontamination supplied by rescue services at the incident scene.
In order to determine Emergency Exposure Limits for toxic chemical in GB18218-2009 Identification of Major hazard installations for dangerous chemicals in China, overview of Emergency Exposure Limits was firstly introduced, including Acute Exposure Guideline Level, Emergency Response Planning Guideline, Temporary Emergency Exposure Limit and so on, then attention was paid on the differences and hierarchies of alternative Emergency Exposure Limits, finally Emergency Exposure Limits for toxic chemical in Major hazard installations of China were established based on the following sequences: Acute Exposure Guideline Level, Emergency Response Planning Guideline and Temporary Emergency Exposure Limit. This kind of data migration is feasible, which would be the most economical and effective way in the process of establishing the China's own Emergency Exposure Limit system.1
Chlorine (Cl2; CASRN 7782-50-5) was the first gas to be used as a chemical warfare agent during the First World War and is widely utilized today in industry (e.g. oxidizing agent in water treatment; pulp mills). The immediate effects from acute exposure are well documented but the long term sequelae from an acute exposure are not well understood. Several studies were reviewed that discuss the long term outcome of an acute exposure to chlorine gas and their conclusions appear contradictory. This may be due to different endpoints being assessed, to the existence of lung diseases prior to exposure, or even the effects of smoking. The concentration and duration of chlorine exposure would also play a role in the potential for long term sequelae and few of the studies reviewed provided this information. Animal inhalation toxicology experiments that studied the potential for long term effects after an acute exposure to chlorine noted that the observed effects may resolve over time. An intrinsic limitation of animal studies is the difficulty of extrapolating to humans. Thus, from peer-review human and animal literature, it is difficult to conclusively determine if there are long term effects after an acute exposure to chlorine gas.
In this paper, we compare acute toxic gas standards developed for occupational, military, and civilian use that predict or establish guidelines for limiting exposure to inhaled toxic gases.
Large disparities between guidelines exist for similar exposure scenarios, raising questions about why differences exist, as well as the applicability of each standard. The motivation and rationale behind the development of the standards is explored with emphasis on the experimental data used to set the standards.
The Toxic Gas Assessment Software (TGAS) is used to quantitatively compare current acute exposure standards, such as: Acute Exposure Guidelines (AEGL), Immediate Danger to Life or Health (IDLH), Purser, International Organization for Standardization (ISO 13571), and Federal Aviation Administration (FAA). The TGAS software does this by calculating the body-mass-normalized internal doses of each gas exposure in each standard, which is then plotted on a cumulative distribution function for a normal or susceptible population to visualize the relationship of the standards to each other. To focus the comparison, acute toxic gas standards for five common fire gases, carbon monoxide (CO), hydrogen cyanide (HCN), hydrogen chloride (HCl), nitrogen dioxide (NO₂), and acrolein (C₃H₄O), are explored. Results: It was found that differences between standards can be reconciled when the target population, effect endpoint, and incidence level are taken into account.
By analyzing the standards with respect to these factors, we can acquire a better understanding of the applicability of each.
The calculation of damage level due to the exposure to a toxic cloud is usually not included in most popular software, or it is included using techniques that do not take into account the variation in concentration over a period of time. In this work, a method is introduced for calculating the temporal evolution of the potential damage level and to obtain a more precise and descriptive estimation of this level. The proposed goal is:
to estimate the maximum and minimum damage level experienced by a population due to the exposure to an airborne chemical with a time‐varying concentration;
to be able to assess the damage level experienced in a progressive way, as the exposure to the airborne chemical occurs.
The method relies on transformations of time‐concentration pairs on a continuum of damage level curves based on the available guideline levels, obtaining maximum and minimum approximations of the expected damage level for any exposure duration. Consequently, applying this method to transport model output data and demographic information, damage evolution in relation to time and space can be predicted, as well as its effect on the local population, which enables the determination of threat zones. The comparison between the proposed method and the current (Spanish and ALOHA) ones showed that the former can offer a more precise estimation and a more descriptive approach of the potential damage level. This method can be used by atmospheric dispersion models to compute damage level and graphically display the regions exposed to each guideline level on area maps.
The Chemical Mixture Methodology (CMM) is used for emergency response and safety planning by the US Department of Energy, its contractors and other private and public sector organizations. The CMM estimates potential health impacts on individuals and their ability to take protective actions as a result of exposure to airborne chemical mixtures. It is based on the concentration of each chemical in the mixture at a designated receptor location, the protective action criteria (PAC) providing chemical-specific exposure limit values and the health code numbers (HCNs) that identify the target organ groupings that may be impacted by exposure to each chemical in a mixture. The CMM has been significantly improved since its introduction more than 10 years ago. Major enhancements involve the expansion of the number of HCNs from 44 to 60 and inclusion of updated PAC values based on an improved development methodology and updates in the data used to derive the PAC values. Comparisons between the 1999 and 2009 versions of the CMM show potentially substantial changes in the assessment results for selected sets of chemical mixtures. In particular, the toxic mode hazard indices (HIs) and target organ HIs are based on more refined acute HCNs, thereby improving the quality of chemical consequence assessment, emergency planning and emergency response decision-making. Seven hypothetical chemical storage and processing scenarios are used to demonstrate how the CMM is applied in emergency planning and hazard assessment.
Production of plutonium for the United States' nuclear weapons program from the 1940s to the 1980s generated 53 million gallons of radioactive chemical waste, which is stored in 177 underground tanks at the Hanford site in southeastern Washington State. Recent attempts to begin the retrieval and treatment of these wastes require moving the waste to more modern tanks and result in potential exposure of the workers to unfamiliar odors emanating from headspace in the tanks. Given the unknown risks involved, workers were placed on supplied air respiratory protection. CH2MHILL, the managers of the Hanford site tank farms, asked an Independent Toxicology Panel (ITP) to assist them in issues relating to an industrial hygiene and risk assessment problem. The ITP was called upon to help determine the risk of exposure to vapors from the tanks, and in general develop a strategy for solution of the problem. This paper presents the methods used to determine the chemicals of potential concern (COPCs) and the resultant development of screening values and Acceptable Occupational Exposure Limits (AOELs) for these COPCs. A total of 1826 chemicals were inventoried and evaluated. Over 1500 chemicals were identified in the waste tanks headspaces and more than 600 of these were assigned screening values; 72 of these compounds were recommended for AOEL development. Included in this list of 72 were 57 COPCs identified by the ITP and of these 47 were subsequently assigned AOELs. An exhaustive exposure assessment strategy was developed by the CH2MHILL industrial hygiene department to evaluate these COPCs.
The Homeland Security Presidential Directive #8 (HSPD-8) for National Emergency Preparedness was issued to " establish policies to strengthen the preparedness of the United States to prevent and respond to threatened or actual domestic terrorist attacks, major disasters, and other emergencies by requiring a national domestic all- hazards preparedness goal. "In response to HSPD-8 and HSPD-22 (classified) on Domestic Chemical Defense, the US Environmental Protection Agency (US EPA) National Homeland Security Research Center (NHSRC) is developing health-based Provisional Advisory Levels (PALs) for priority chemicals (including chemical warfare agents, pesticides, and toxic industrial chemicals) in air and drinking water. PALs are temporary values that will neither be promulgated, nor be formally issued as regulatory guidance. They are intended to be used at the discretion of risk managers in emergency situations. The PAL Program provides advisory exposure levels for chemical agents to assist in emergency planning and response decision-making, and to aid in making informed risk management decisions for evacuation, temporary re-entry into affected areas, and resumed-use of infrastructure, such as water resources. These risk management decisions may be made at the federal, state, and local levels. Three exposure levels (PAL 1, PAL 2, and PAL 3), distinguished by severity of toxic effects, are developed for 24-hour, 30-day, 90-day, and 2-year durations for potential exposure to drinking water and ambient air by the general public. Developed PALs are evaluated both by a US EPA working group, and an external multidisciplinary panel to ensure scientific credibility and wide acceptance. In this Special Issue publication, we present background information on the PAL program, the methodology used in deriving PALs, and the technical support documents for the derivation of PALs for acrylonitrile, hydrogen sulfide, and phosgene.
Facilities using hazardous substances are required to comply with risk management programs that aim to reduce the frequency of chemical accidents and the severity of consequences in the event of an accident. Both the European Union and the United States use chemical-specific weight thresholds for toxic substances to determine those facilities and processes that must comply with such programs. This study evaluates whether the establishment and use of these 'threshold quantities' is consistent and protective of public health. The chemical footprint or hazard zone length is calculated using current threshold quantities and 'level of concern' (LOC) concentrations for 77 toxic chemicals in the US regulations. Using the worst-case scenario and the recommended procedure involving the Risk Management Program (RMP)*Comp, footprint lengths range up to 40 km. However, the RMP*Comp program provides inconsistent results. Threshold quantities are then calculated using an atmospheric dispersion model and several meteorological and land-use scenarios. In the base scenario (winds at 4.3 m/s, neutral stability, urban conditions, and distances of 100, 250, and 1000 m), distance-based weight thresholds are considerably smaller than current listings for most toxic substances. Distance-based and current thresholds have low correlation (e.g. r=0.34) and large discrepancies (e.g. differences up to three orders of magnitude). Alternative scenarios evaluated for distance-based threshold quantities, which used using stable atmospheres and rural settings further reduce the distance-based weight thresholds and increase discrepancies. Linear relationships are shown between threshold quantities and level of concerns for each scenario and dispersion mode (neutral or dense) that allow simple calculation of threshold quantities. The current thresholds may exclude facilities that could pose significant off-site risks, and the thresholds are inconsistent with the off-site consequence analysis (OCA). Recommendations include revising the threshold quantities that determine covered facilities/processes; modifying RMP*Comp to eliminate errors; establishing threshold quantities using a more rational approach, e.g. based on hazard zones or distances using credible scenarios; and using the same health-based level of concern in both initial screening and subsequent off-site consequence analyses.
A number of organizations have developed acute inhalation health reference values, each with (1) a specific purpose, (2) populations to protect, (3) exposure scenarios (accidental releases, workplace, routine excursions of ambient levels), and (4) severity of adverse health effects considered in their development. The first section of this article reviews the existing values from different organizations and describes their purposes and method of development. The second part of the article provides a comparative review of how the values were derived, the critical endpoints considered for each value, the populations being protected by each value, and the potential for use outside of their intended purpose (e.g., Homeland Security, regulatory analysis, etc.). Additionally, an analysis of the acute inhalation reference values that was developed in support of the Office of Air and Radiation's residual risk assessment for hazardous air pollutants is presented and reviewed. The third and final part of the article focuses on the efforts of the U.S. Environmental Protection Agency (EPA) to develop a set of less-than-lifetime reference values, along with a discussion of how that effort fits with the existing sets of values described in the prior sections.
A large reference database consisting of acute inhalation no-observed-adverse-effect levels (NOAELs) and acute lethality data for 97 chemicals was compiled to investigate two methods to derive health-protective concentrations for chemicals with limited toxicity data for the evaluation of one-hour intermittent inhalation exposure. One method is to determine threshold of concern (TOC) concentrations for acute toxicity potency categories and the other is to determine NOAEL-to-LC(50) ratios. In the TOC approach, 97 chemicals were classified based on the Globally Harmonized System of Classification and Labeling of Chemicals proposed by the United Nations into different acute toxicity categories (from most toxic to least toxic): Category 1, Category 2, Category 3, Category 4, and Category 5. The tenth percentile of the cumulative percentage distribution of NOAELs in each category was determined and divided by an uncertainty factor of 100 to derive the following health-protective TOC concentrations: 4microg/m(3) for chemicals classified in Category 1; 20microg/m(3) for Category 2; 125microg/m(3) for both Categories 3 and 4; and 1000microg/m(3) for Category 5. For the NOAEL-to-LC(50) ratio approach, 55 chemicals with NOAEL exposure durations < or = 24 hour were used to calculate NOAEL-to-LC(50) ratios. The tenth percentile of the cumulative percentage distribution of the ratios was calculated and divided by an uncertainty factor of 100 to produce a composite factor equal to 8.3x10(-5). For a chemical with limited toxicity information, this composite factor is multiplied by a 4-hour LC(50) value or other appropriate acute lethality data. Both approaches can be used to produce an estimate of a conservative threshold air concentration below which no appreciable risk to the general population would be expected to occur after a one-hour intermittent exposure.
The EU Control of Major Accidents Hazards Directive (Seveso II) requires an external emergency plan for each top tier site. This paper sets out a method to build the protection of public health into emergency planning for Seveso sites in the EU. The method involves the review of Seveso site details prescribed under the directive. The site safety report sets out the potential accident scenarios. The safety report's worst-case scenario, and chemical involved, is used as the basis for the external emergency plan. A decision was needed on the appropriate threshold value to use as the level of concern to protect public health. The definitions of the regulatory standards (air quality standards and occupational standards) in use were studied, how they are derived and for what purpose. The 10 min acute exposure guideline level (AEGL) for a chemical is recommended as the threshold value to inform decisions taken to protect public health from toxic cloud releases. The area delimited by AEGL 1 defines the population who may be concerned about being exposed. They need information based on comprehensive risk assessment. The area delimited by AEGL 2 defines the population for long-term surveillance when indicated and may include first responders. The area delimited by AEGL 3 defines the population who may present acutely to the medical services. It ensures that the emergency responders site themselves safely. A standard methodology facilitates discussions with plant operators and concerned public. Examples show how the methodology can be adapted to suit explosive risk and response to fire.
Emergency Response Planning Guideline (ERPG) values are the only well-documented exposure limits developed to date specifically for use in evaluating the health consequences of exposure of the general public to accidental releases of extremely hazardous chemicals. Because ERPG values have so far been developed for relatively few chemicals, there is a need for alternative guidelines to be used for other chemicals. The objective of this work was to provide consistent methodology for the selection of reasonable interim values for these chemicals until such time as official ERPGs are developed. Most of the commonly available published and documented concentration-limit parameters were considered. ERPG values should be used as the primary guidelines for chemical emergency planning. Alternatives are recommended for use when ERPGs are not available. The parameters are to be used in the order presented, based on availability for the chemical of interest. Though these concentration limits were developed for different purposes, and were intended specifically for occupational use, no other options were available. Nonoccupational populations include the young, the aged, and other hypersensitive individuals. For each chemical, the adoption of alternatives to ERPGs should be carefully evaluated.
The US Department of Transportation's 1990 Emergency Response Guidebook will provide an updated Initial Isolation and Protective Action Distances Table guiding first responders during the first 30 minutes of a toxic chemical release from a transportation accident. This paper summarizes the methodology and models used to prepare that table and discusses the major technical issues that were faced in its development. The modeling carried out for the 1990 Table attempted to improve the physics of the source-term release and atmospheric dispersion. Realistic gaseous and liquid accident release scenarios were identified for each of 140 chemicals. The downwind impact was then computed for releases of each chemical from a variety of appropriate container sizes. Among the submodels used in the source-term and transport modeling were gaseous and liquid release models for the various sizes of containers, pool evaporation models, a flashing model, and an atmospheric dispersion model. A key issue for future study involves the use of the various toxicological guidelines that are presently available for the various chemicals, considering that no single exposure limit has been determined for all chemicals of interest for emergency response planning, and there is no uniform guidance by the toxicologists on the use of the various exposure guidelines in the presence of time-dependent exposures. 10 refs., 2 figs., 2 tabs.
This document is one in a series prepared by the Committee that form the basis of the recommendations for EELs and CELs for selected chemicals. Since the Committee began recommending EELs and CELs for its military sponsors (U.S. Army, Navy, and Air Force), the scope of its recommendations has been expanded in response to a request by the National Aeronautics and Space Administration. The CELs, in particular, grew out of a Navy request for exposure limits for atmospheric contaminants in submarines. The EELs and CELs have been used as design criteria by the sponsors in considering the suitability of materials for particular missions (as in a submarine or a spacecraft) and in assessing the habitability of particular enclosed environments. They are recommended for narrowly defined occupational groups and are not intended for application in general industrial settings or as exposure limits for the general public.
This report presents the re-evaluation of the raw data of previously published acute inhalation toxicity studies of some volatile industrial chemicals. In these studies both concentration and exposure time were varied. The raw data were obtained from an extensive literature search and were subjected to probit analysis. The results show that the product of concentration and exposure time (ct) is not always a good parameter for predicting the mortality response (Haber's rule). On the contrary, the term cnt, in which the exponent n is different from 1, often predicts the response very well.
Sumario: Introduction to the problem and review of current approaches -- Secondary data sources -- An approach for the rapid development of scientifically defensible AALs -- Chemical-specific assessments.
Vol. II comprende de la A-E y Vol. III de la F-Z
Occupational Exposure Limits for Airborne Toxic Substances, Third Edition: Values of Selected Countries prepared from the ILO-CIS Data Base of Exposure Limits, ISBN 92-2-107293-2
- Lnternational
- Labor
lnternational Labor Office, Occupational Exposure Limits for Airborne Toxic Substances, Third Edition: Values of Selected Countries prepared from the ILO-CIS Data Base of Exposure Limits, ISBN 92-2-107293-2. International Labor Office, Geneva (1991).
Funf Vortage aus den Jahren 1920-1923: No. 3, Die Chemie i m Kriege
- F Haber
F. Haber, Funf Vortage aus den Jahren 1920-1923: No.
3, Die Chemie i m Kriege, pp. 76-92. Verlag von Julius
Springer, Berlin (1924).
Methodology for Deriving Temporary Emergency Exposure Limits ITEELsl. WSRC-TR-98-00080 This technical report is available on the World Wide Web on SCAPA's Home Page
- D K Craig
- C R Lux
D. K. Craig and C. R. Lux, Methodology for Deriving
Temporary Emergency Exposure Limits ITEELsl.
WSRC-TR-98-00080 (1998). This technical report is available on the World Wide Web on SCAPA's Home Page:
'http://www.scapa.bnI.gov/'.
The AIHA 1998 Emergency Response Planning Guidelines and Workplace Environmental Exposure Level Guides Handbook
- American Lndustrial
- Hygiene Association
American lndustrial Hygiene Association, The AIHA 1998
Emergency Response Planning Guidelines and Workplace
Environmental Exposure Level Guides Handbook. AIHA
Press, Fairfax, VA (1998).
The AIHA 1999 Emergency Response Planning Guidelines and Workplace Environmental Exposure Level Guides Handbook
- American Lndustrial
- Hygiene Association
American lndustrial Hygiene Association, The AIHA 1999
Emergency Response Planning Guidelines and Workplace
Environmental Exposure Level Guides Handbook. AIHA
Press, Fairfax, VA (1999).