ENVIRONMENTAL RISK ASSESSMENT:
APPLICATIONS TO HAZARDOUS WASTE SITES

EV-595
 Fall Semester 1997
Prerequisites:
General chemistry
Knowledge of algebra
Basic computer skills
General biology (recommended)
Introductory statistics (recommended) 		Meeting:
Wednesday 6:30 - 9:15 p.m.
Perkins Hall
Room 102

Office hours: To be arranged
Instructors and phone numbers:
Richard R. Bonczek (423) 576-1548
Bobette D. Nourse (423) 241-2369 		E-mail:
1bz@ornl.gov
NOURSEBD@aol.com; nu5@ornl.gov

Grading:
11 Quizzes or Homework after/during most lectures, each worth approximately 30 points for a total of 300 points (30 % of total grade);
Class Project, 500 points;
and a take-home Final Exam, 200 points (Project & Final Exam worth 70% of total grade).

Grading scale:
> 90% = A;
> 80% = B;
> 70% = C;
and > 60% = D.

Class project:
The class project will consist of sample data sets that will be used to perform a human health risk assessment following the steps that will be discussed in class.

Students will be provided with the following materials needed to complete the class project:
(1) Site description and site map(s)
(2) Conceptual site model (students will develop these in class)
(3) Toxicity profiles
(4) Toxicity values
(5) Data sets with sampling location information (e.g., maps)

Textbooks and documents:

Risk Assessment Guidance for Superfund, Volume I, Parts A, B, and C. US EPA (EPA/540/1­89/002) - Available at the UT Bookstore. [This document series is held by the UT Library and is available on Microfiche].

Calculated Risks: Understanding the toxicity and human health risks of chemicals in our environment, by Joseph V. Rodricks, published by Cambridge University Press (paperback) - Available at the UT Bookstore.
Other documents and handouts will be made available for reading and/or copying.


Access to an CAFE Account:
Students are encouraged to access a CAFE account with the University of Tennessee Computing
Center for access to e­mail and project information.

Course Outline
I. Introduction and Procedures for Performing a Human Health Risk Assessment (HHRA) A. Introduction to the instructors, the course, the project, and the syllabus
B. A short history of risk assessment (Regulatory Bases), HHRA in everyday life, and types of risk assessments; relationship between human health and ecological risk assessments

II. Exposure Assessment
A. Characterizing the exposure setting
  • 1. Physical Environment.
  • 2. Exposed or potentially exposed populations.
    B. Identifying exposure pathways / pathway analysis
  • 1. Sources of contamination and mechanisms of release.
  • 2. Transport mechanisms, exposure point development, and exposure routes.
    C. Developing and presenting the conceptual site model / A structured way to make decisions
  • 1. The cartoon, the stem-and-leaf, and the ASTM model: advantages and disadvantages.
    D. Quantification of Exposure / Calculation of the Chronic Daily Intake
  • 1. Exposure factors, exposure parameters, and the generic equation(s).
    The concept of Reasonable Maximum Exposure (RME) / Calculating the RME dose. Development of exposure parameters including site-specific values.
  • 2. End-point specific calculations of dose.
    Carcinogenesis. Systemic toxicity hazard.
  • 3. Chronic versus subchronic exposures.
    E. Presentation of the Exposure Assessment
    F. Uncertainties associated with the Exposure Assessment
    G. Human health risk-based Preliminary Remediation Goals (PRGs)
  • 1. Calculation of risk-based PRGs.
  • 2. Relationship of risk-based PRGs to EPA's soil screening levels (SSLs) and Maximum Contaminant Levels (MCLs).

    III. Data Requirements for Risk Assessments
    A. Data sources
  • 1. Historical data and process-knowledge information.
    Review of historical data and the quality of these data.
    B. Data Quality Objectives (DQOs)
  • 1. How rigorous does the data have to be?
    What decisions are going to be made? Baseline HHRA versus a Screening Risk Assessment. What data are necessary to meet DQOs? Nature and Extent versus Risk Characterization. Politics. Develop list of analytes to be sampled.
  • 2. Data quality steps.
  • 3. Environmental sampling / planning.
    Site-related contaminant concentrations. Background levels/concentrations.
  • 4. Reproducibility and validation.
  • 5. Media­specific sampling.
  • 6. Meeting EPA sampling requirements.
    C. Analytical analyses, requirements, and detection limits
    D. Introduction to modeling
  • 1. Fate and transport data needs, contaminant migration, exposure times, and concentrations of contaminants in the environment.
  • 2. Model selection and description of useful models.
    E. Data evaluation
  • 1. Precision, accuracy, reproducibility, comparability, and completeness (PARCC).

    IV. Data Assessment, Evaluation, and Reduction
    A. Assessment of the data
  • 1. Do data meet DQOs?
    Locations, media, depths, etc., sampled? Analyte list complete? Analytical methods correct and detection limits low enough for HHRA? Sherlock Holmes.
    B. Data evaluation
  • 1. Evaluation of lab and validation qualifiers.
  • 2. Comparison of sample concentrations with, for example, field blank & lab blank sample concentrations (i.e., the 5X and 10X rule).
  • 3. Duplicate-sample concentration comparisons against regular-sample concentrations.
  • 4. Statistical comparisons between historical and new data & statistical comparisons for outliers.
  • 5. Evaluation of Tentatively Identified Compounds (TICs).
    C. Statistical comparisons / screenings
  • 1. Development of site-related contaminants.
    Screening against detection limits. Screening against background concentrations. Site history (e.g., weight-of-evidence).
  • 2. Development of Contaminants of Potential Concern (COPCs).
    Screening against risk-based PRGs, and comparisons with MCLs and other chemical-specific ARARs. Essential nutrients.
    D. Calculation of representative exposure concentrations
    E. Presentation of data evaluation(s), screenings, and summary statistic information
    F. Associated uncertainties

    V. Toxicity Assessment
    A. Exposure routes
    B. Sources of toxicity and types of toxicity (carcinogenic and noncarcinogenic)
    C. Toxicity values
  • 1) Where do they come from?
  • 2) How were they developed?
  • 3) Site-specific values.
  • 4) Associated Uncertainties.
    D. Radiation assessment (chemical toxicity versus ionizing radiation)
    E. Presentation of Toxicity Assessment
    F. Uncertainties associated with the Toxicity Assessment

    VI. Risk Characterization
    A. Calculating human health risks and hazard quotients.
  • 1) Characterization of human health risks and hazards / Pulling it all together
    B. Presentation of risk/hazard information (tables and graphics).
    C. Identifying contaminants of concern (COCs), pathways of concern (POCs), and uses of concern.
    D. Uncertainties / Qualitative and quantitative effects on risk and hazard calculations
    E. Development of Remedial Goal Options (RGOs)
  • 1) What are appropriate RGOs and when/why/how are they determined?
  • 2) How do RGOs differ from PRGs?
  • 3) Calculating RGOs.

    VII. Introduction to Uncertainty Analyses
    A. Qualitative Uncertainty Analysis
    B. Sensitivity Analysis
    C. Quantitative Uncertainty Analysis and Probabilistic Risk Assessment
    D. Presentation of the Uncertainty Analysis
    E. Guide to further investigations / meeting the DQOs
    F. Management of Uncertainty

    VIII. Introduction to Risk Communication (if time permits)
    A. Public perception and influence / risk communication

    IX. Introduction to Ecological Risk Assessment (if time permits)

    X. Introduction to Risk Management (if time permits)
    A. Modifying the conceptual site model
    B. Remedial Action Objectives (RAOs) and risk reduction
    C. Risk assessment in corrective actions

    Last Revised: August 26, 1997

    claubergm@mindspring.com -- 26-Aug-1997