 Chemical Parameters
RISC WorkBench - US EPA Risk Assessment Guidance for Superfund (US EPA, 1989), model to calculate exposure assessment, toxicity assessment and risk assessment RISC WorkBench Categories: RISC WorkBench Details Introduction Introduction to RISC WorkBench RISC WorkBench 4.0 is an easy-to-use software package designed for performing fate and transport modeling and human health risk assessments for contaminated sites. RISC WorkBench follows standard procedures outlined in the US EPA's Risk Assessment Guidance for Superfund (US EPA, 1989) to calculate exposure assessment, toxicity assessment, and risk assessment. RISC WorkBench also includes EnviroBrowser Pro, a completely customizable database for common environmental parameters used when conducting risk assessments. No other RISK package offers all this! The RISC WorkBench follows a logical menu structure that takes you through the necessary steps to produce your risk analysis or contaminant transport model run. Simply complete the 6 steps outlined in RISC WorkBench to obtain results quickly. If you're not sure of an input parameter, simply launch the chemicals or environmental parameters database for a selection of common 'risk' parameters!
***RISC WorkBench is a stand-alone product and does not require Microsoft Excel unless using the bonus "Tier 1 Levels Spreadsheet" or the "Water Quality Database."
Step 1: Select Chemicals of Concern RISC WorkBench allows you to select from over 86 common chemicals providing physical, chemical, and toxicity values or add new compounds. Step 2: Define Exposure Pathways In Step 2, the user may define the exposure scenario by selecting contaminated media(s), fate and transport models (if any), and associated exposure pathways. RISC WorkBench is set up so that in any single analysis, either human health exposure pathways can be evaluated or ecological/water quality concerns can be evaluated. Built-in Fate & Transport Models include:
Step 3: Determine Receptor Point Concentrations The third step is to determine receptor point concentrations for the various media of concern specified in Step 2. There are two methods for determining receptor point concentrations; the user can enter receptor point concentrations directly into RISC WorkBench or enter source zone concentrations and then utilize chemical fate and transport models to estimate the receptor point concentrations. The method(s) to be used in Step 3 are determined by the choices made in Step 2.
Step 4: Enter Surface Water & Sediment Criteria In Step 4, the receptor(s) of concern are chosen and the receptor-specific intake parameters are entered. RISC WorkBench contains both deterministic and stochastic (Monte Carlo input) default data on exposure for many different types of receptors. The user is free to use the default data provided or to change the intake parameters to reflect actual site-specific values.
Step 5: Calculate Risk & Cleanup Levels The potential carcinogenic risk and non-carcinogenic hazard are calculated using equations presented in EPA's Risk Assessment Guidance for Superfund (EPA, 1989a). The following exposure routes are considered in the software:
Pathways 1-3 and 6-7 represent some of the more common exposure pathways for many petroleum contaminated sites (e.g., former gas stations). If surface water bodies are present on the site, exposure pathways 8 and 9 may be important. Pathways 11-14 represent the potential pathways associated with irrigation water and will usually only be of concern if the house has its own well while drinking water used in the house is provided by a municipality. When the "Calculate Clean-up Levels" option is chosen from Step 5, RISC WorkBench can be used to "back-calculate" clean-up levels using the models and assumptions selected in the current analysis. In the "forward risk" assessment, risk is calculated from input or estimated receptor point concentrations and receptor input parameters. In the back-calculation, the user specifies target risks or concentrations (e.g., MCLs) and then the software calculates "allowable" source concentrations (clean-up levels). The clean-up levels represent source and/or receptor point concentrations for the chemicals of concern such that the risk levels are not exceeded for the scenario outlined. There are several options for selecting targets in Step 5. The user may specify a target risk or hazard index either for individual chemicals or for a cumulative scenario where the risks are summed across all chemicals of concern. If groundwater or surface water is a receptor media, the user may enter target concentrations (e.g., MCLs in groundwater) for these media.   
 RISC WorkBench Compared to the RBCA ToolKit While slightly similar to the RBCA Toolkit, RISC WorkBench is more functional, flexible and user-friendly. The major differences are:
RISC WorkBench includes a comprehensive user's manual containing three in-depth example problems. Technical support is provided by phone, fax or e-mail. Risk WorkBench Hardware Requirements
RISC WorkBench can be run without Excel, however, this will prevent the user from displaying the bonus RBCA Tier 1 table or accessing the full surface water and sediment criteria databases. Toxicity Parameters
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