Important Terms Continued

Transcription

1 EOH 2515 Environmental & Occupational Health Preparedness Lecture 1, Development of Conceptual Site Models for Chemical/Physical Hazard Preparedness; Their Relationship to Contaminant Mass Balance and Exposure Assessment Conrad (Dan) Volz, DrPH, MPH Assistant Professor, Environmental and Occupational Health, University of Pittsburgh, Graduate School of Public Health Director-Center for Healthy Environments and Communities Director, Environmental Health Risk Assessment Certificate Program

2 Important Terms Agent(s) -biological, chemical, physical, single agent, multiple agents, mixtures Source(s)- anthropogenic/non-anthropogenic, area/point, stationary/mobile, indoor/outdoor Transport/carrier medium- air, water, soil, dust, food, product/item Exposure pathways(s)- eating contaminated food, breathing contaminated workplace or ambient air, touching residential/municipal surfaces or bathing in contaminated water.

3 Important Terms Continued Exposure concentration- mg/kg (food), mg/litre (water), μg/m3 (air), μg/cm2 contaminated surface), fibres/m3 (air), percent by weight or ppm (mg/kg) for contaminated soils. Exposure route(s) -inhalation, dermal contact, ingestion, multiple routes. Exposure duration- seconds, minutes, hours, days, weeks, months, years, lifetime, population-generational. Exposure frequency- continuous, intermittent, cyclic, random, rare. Exposure setting(s) -occupational/non-occupational (environmental), residential/non-residential, indoors/outdoors, recreational/non-recreational, catastrophic event (acute and chronic). Exposed population- general population, population subgroups, individuals. Geographic scope- site/source specific, local, regional, national, international, global. Time frame- past, present, future, trends.

4 Definition of Environmental Media - Air Surface Water Groundwater Sediment Soil Subsurface area-vadose Zone Food Chain

5 Components of Environmental and Occupational Health Exposure Pathways Source (s) Often with unique fingerprint(s). Rate(s) of contaminant emissions. Transport route(s) through environmental media. Route(s) of exposure. Exposure concentration(s).

6 Exposure and Dose Assessment Relationship to the Environmental Health Paradigm

7 Occupational/Environmental Exposure Definition Exposure is defined as contact over time and space between a -person and one or more biological, chemical or physical agents (US NRC, 1991a). -an ecological receptor and one or more biological, chemical or physical agents.

8 Factors Influencing Human Exposure The duration, frequency and intensity of contact with the contaminant. How Long/Often and Much? Identification of individual activity patterns, population distributions and susceptible populations.

9 Mathematical Expressions- Exposure and Dose

10 What is a Conceptual Site Model? A written and/or pictorial representation of an environmental system and the biological, physical and chemical processes that determine the transport and fate of contaminants through environmental media to environmental receptors and their most likely exposure modes.

11 Components of a Complete Conceptual Site Model Sources of contaminants (can be multiple sources as well as species on a site). Pathways of environmental transport. Indications of any barriers or remedies that exist or are proposed. Pathways to ecological and human receptors. (Refer to ASTM Handout page 8).

12 Why develop a Conceptual Site Model? Pull together technical data concerning a preparedness problem or contaminated site from numerous sources. Support the selection of sampling locations to establish background concentrations of identified contaminants. Identify data needs and gaps. Describe and integrate the processes that determine contaminant release, migration and human and ecological receptor exposure from any particular preparedness event.

13 Why develop a Conceptual Site Model (continued)? Determine most likely and most important exposure routes (inhalation, ingestion and/or dermal absorption) for humans or ecological receptors. (We need quite often to be concerned for ecological receptors because they comprise the food web for humans). Identify uncertainties in the model that need further study.

14 Why develop a Conceptual Site Model (continued)? Preliminarily evaluate the health risk to human and ecological receptors resulting from any catastrophic release (acute and chronic problems). Facilitate the selection of preparedness plans and evaluate the effectiveness of engineering and personal protective equipment controls to reduce exposure during any event. For use a a communication tool in the decisionmaking process involving experts from exposure assessment, human and ecological health, remediation engineers etc. As a risk communication tool for the public for both preparedness planning and in a crisis event.

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16 CSM of Release of Liquid Radionuclides Can Build This for Contaminated Sites and Industrial/Power or Defense Plants Using Radionuclides Internal Dose Pharmakokinetics Elimination Rate Toxicity and Damage Aquatic Receptors Time Shielding and Distance

17 Pantex Department of Energy Facility and Regional Geographical Factors Beyond the Fence, the Incorporation of These Factors into the CSM Contaminants include U and Trichloroethene---TCE degrades into vinyl chloride, which causes angiosarcoma of the liver. Vyas, Volz and Powers, 2005

18 Water Usage Projections and Conceptual Effects on the Transport of Radionuclides to New Populations Vyas, Volz and Powers 2005

19 Regional CSM of Radionuclide Fate and Transport In the North Pacific/ Bering Sea Ecosystem CRESP.org Burger et al.

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