Exposure modeling

NUCRAC improves on the health effects model by a reexamination of Hiroshima and Nagasaki data. The dry deposition model was much improved by the inclusion of a particle-si/e distribution, a detailed settling model, and a detailed chronic exposure model via the food pathway. However, it does not include a rainout model. 

ERA S Exposure Model Library and Integrated Model Evaluation System... 

EPA, 1996, is the third edition of EML/DVIES on CD-ROM for distributing exposure models, documentation, and the IMES about many computer models used for exposure assessment and other fate and transport studies as developed by the EPA s Office of Research and Development (ORD). 

The Exposure Models Library may be accessed either with the DOS EML interface program or with an HTML browser program such as Netscape or Microsoft Internet Explorer. To use the DOS EML interface and to access the IMES, enter the drive letter of your CD ROM drive, set the default directory to EML and then enter EML (e.g D CD EML EML). From the menu, run or download the available models of IMES to your hard disk. Also you may access EML directories with your HTML browser by opening the EMLINTRO.HTM file in the root directory. The HTML... 

EPA s Exposure Model Library and Inlegrated Mode Evahi nu rt. Sv. . i... 

Exposure Models Library and Integrated Model Evaulation System, EPA/ C-... 

Dr. Richard Walentowicz provided the EPA CD-ROM disk entitled Exposure Models Library and Integrated Model Evaluation System" with other reference material. Lester Wittenberg of the Center for Chemical Process Safety, AIChE was particularly helpful in providing a chenncal industry perspective and reference material as was Dr. Steven Arendt of JBF Associates, Inc. Drs. David Hesse of Battelle Columbus Laboratories and Vinod Mubayi of Brookhaven National Laboratory were very helpful in providing material on the chemical consequence codes. 

Other models (or combinations of them) are often employed when computers are used to analyze dispersal. These can give an acceptable degree of accuracy when combined with detailed weather data. Short-exposure modeling is the most difficult and is liable to the greatest degree of error. It is for this reason that such models are not accurate when dealing with odor nuisances. The problem of modeling odor dispersal is dealt with below. 

Skinner CS, Kilgore WW. 1982b. Application of a dermal self-exposure model to worker reentry. J Toxicol Environ Health 9 461-481. 

Fisher JW, Whittaker TA, Taylor DH, et al. 1989. Physiologically based pharmacokinetic modeling of the pregnant rat A multiroute exposure model for trichloroethylene and its metabolite, trichloroacetic acid. Toxicol Appl Pharmacol 99 395-414. 

Health Canada Proposal for Priority Setting for Existing Substances on the Domestic Substances List under the Canadian Environmental Protection Act, 1999 Greatest Potential for Human Exposure. This report describes a proposed priority setting process of existing substances in Canada. A stakeholder meeting was convened to discuss the Complex Exposure Model (comET). 

Mokhtari, A. and Jaykus, L. A. (2009). Quantitative exposure model for the transmission of norovirus in retail food preparation. Int. ]. Food Microbiol. 133,38-47. 

It is presumed that the effect of carcinogenic materials is to produce critical cell damage. Thus, carcinogenic health effects models generally are dose (i.e., integrated exposure) models, not exposure models. The lack of firm statistical bases often leads to the adoption of nonthreshold, linear models, even though thresholds and nonlinear effects might be expected. 

Anderson Human Exposure Models Airborne Materials... 

T. Johnson and R. Paul, "The NAAQS Exposure Model (NEM) and Its Application to Nitrogen Dioxide," PEDCo Environmental, Inc., Durham, North Carolina, 1981. 

Receptor Exposure. Exposure modeling should produce a statistically representative profile of pollutant intake by a set of receptors. This is done by combining the space/time distribution of pollutant concentrations with that of receptor populations (whether they be people, fish, ducks or property made of some material that is vulnerable to pollutant damage). The accuracy and resolution of the exposure estimates are chosen to be consistent with the main purposes of decision making. These purposes include the following ... 

Because the significance of exposure has only been considered over the past few years, there is not as wide a selection of exposure models available as that for fate models. The latter have been applied for several decades to the calculation of ambient exposure levels compared with some standard values. Papers illustrative of human exposure assessments in this symposium include one on airborne pollutant exposure assessments by Anderson (2), a generic approach to estimating exposure in risk studies by Fiksel (5), and a derivation of pollutant limit values in soil or water based on acceptable doses to humans by Rosenblatt, Small and Kainz (6). 

Field Applicability Testing (FAT) Workshop. In March 1982, the EPA Office of Research and Development convened a workshop with the specific objectives to (1) assess the state of knowledge on determining the field applicability of laboratory bioassay tests, toxicity studies, microcosm studies, and mathematical chemical exposure models (i.e., the extent to which these methods have been tested/compared with field data), and (2) recommend research objectives and priorities to advance the current level of field testing. Workshop attendees included representatives from EPA research laboratories, universities, and private industry. 

Working groups were organized with specific responsibility to assess the utility and limits of four different methods (or tools) currently used by EPA and industry for evaluating hazards posed by toxic chemicals (1) laboratory toxicity data, (2) microcosm test data, (3) site-specific data, and (4) chemical fate and exposure model results. The Exposure Modeling Committee (3.) report presented an assessment of the current extent of field model testing and recommendations for future testing efforts. 

Exposure Modeling Committee Report. Testing for the Field Applicability of Chemical Exposure Models. Proc. Workshop on Field Applicability Testing. U.S. EPA, Athens, GA.,... 

For a limited number of exposure pathways (primarily inhalation of air in the vicinity of sources), pollutant fate and distribution models have been adapted to estimate population exposure. Examples of such models include the SAI and SRI methodologies developed for EPA s Office of Air Quality Planning and Standards (1,2), the NAAQS Exposure Model (3), and the GEMS approach developed for EPA s Office of Toxic Substances (4). In most cases, however, fate model output will serve as an independent input to an exposure estimate. 

L. Hall, "The OTS Graphical Exposure Modeling System (GEMS)." Pre-publication Draft, EPA Office of Toxic Substances, July 20, 1982. 

Angle CR, Marcus A, Cheng I-H, et al. 1984. Omaha childhood blood lead and environmental lead A linear total exposure model. Environ Res 35 160-170. 

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