Human Health Risk Assessment and Risk Management

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Human Health Risk Assessment and Risk Management

• Julie Wroble
• EPA Region 10 Toxicologist
• wroble.julie_at_epa.gov

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What is Risk Assessment

• Scientific approach for evaluating potential for
  harm from hazardous substances and activities
• How harmful?
• How important a priority (which chemicals most of
  concern, comparative risk)?
• How clean is clean?

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What Is Risk?
RISK TOXICITY x EXPOSURE
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What Is Risk?
RISK TOXICITY x EXPOSURE
TOXICITY Chemical's ability to cause adverse
effect
EXPOSURE Concentration Route
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BASELINE RISK ASSESSMENT
1. Data Collection and Evaluation
What contaminants exist and are of potential
concern?
2. Exposure Assessment
How might a receptor be exposed on or off site?
3. Toxicity Assessment
At what level of exposure are adverse effects
likely to occur?
4. Risk Characterization
What are the risks and uncertainties at this
site?
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Human Health Risk Assessment
Data Collection and Evaluation
Exposure Assessment
Toxicity Assessment
Risk Characterization
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Checklist for Human Health

• What human receptors are near your site?
• Are residential properties close by?
• Is site access restricted?
• What contaminants are present?
• Is there a threat or demonstrated release?
• What media have been impacted?
• What data are available?

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Data Collection and Evaluation

• Identify site-related contaminants of potential
  concern (COPCs) at the site
• Collect data from areas where receptor exposures
  are potentially of concern
• Compare findings to naturally-occurring
  (background) levels near site typically done
  for inorganics only
• Ensure quality control samples are not tainted by
  site activity?

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Exposure Assessment

• Identify and estimate concentrations of chemicals
  potentially affecting human health or ecological
  receptors
• Characterize the site in terms of
• Physical characteristics
• Soil characteristics, surface water location,
  groundwater (flow depth), meteorology
• Exposed populations
• Human activities and land use (recreation,
  residential/industrial/commercial)
• Proximity to release
• Potential future uses

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• Identify exposure pathways
• Develop a conceptual site model
• Determine amount of exposure for each pathway
  using monitoring data or fate and transport models

• Analyze concentrations, frequency and duration of
  contaminant exposure to population groups
• Consider characteristics of affected population
  groups - age of individuals, age, unique exposure
  considerations, other factors

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External Loading Terms
RM 11
RM 2
Navigation Channel Boundary
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Why we take special precautions for children
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Toxicity Assessment

• Compare dose of contaminant with incidence of
  adverse human health effect to ascertain
  relationship (by researchers)
• Determine whether exposure to certain chemicals
  results in adverse health effects
• Evaluate available toxicity information
• Databases - IRIS
• Identify data gaps
• Investigate human health problems near the site

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Risk Characterization

• Combine information gathered in the Exposure
  Assessment and Toxicity Assessment
• Quantify risks to human health from individual
  chemicals and exposure pathways
• Sum risks for various exposure scenarios
• Evaluate cancer risk, non-cancer hazard
  separately
• Describe all assumptions, areas of uncertainty

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Regulatory Basis For Ecological Risk Assessment
CERCLA requires EPA to remediate uncontrolled
hazardous waste sites in a way that protect both
human health and the ENVIRONMENT. (42 USC Sec.
9604) National Contingency Plan requires that
the baseline risk assessment characterize the
current and potential threats to human health and
the ENVIRONMENT. (40 CFR Part 300)
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ECOLOGICAL RISK ASSESSMENT FRAMEWORK
RA-RM Discussion (Planning)
PROBLEM FORMULATION
Data Acquisition Verification And Monitoring
ANALYSIS
Ecological Effects
Exposure
RISK CHARACTERIZATION
RA-DM Discussion
Source U.S. EPA 1992a
Risk Management
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CONTAMINANT EFFECTS ON ECOSYSTEMS

• Reduction in population size
• Change in community structure
• Changes in ecosystem structure and function

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Risk Assessment versus Risk Management

• Risk assessment unbiased scientific approach to
  assessing risk
• Risk management incorporates the results of
  risk assessment, factors in societal values,
  legal mandates, other considerations
• Risk communication is a critical piece of each of
  these

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Risk Management

• The process of weighing policy alternatives and
  selecting the most appropriate regulatory action
  by integrating the results of risk assessment
  with engineering data in addition to social,
  economic, and political concerns to reach a
  decision.

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Communicating Risk

• Human response to risk is not always rational
• Level of risk play little role in acceptability
  to public
• Emotional response often makes it difficult to
  communicate risk
• People apply personal values when evaluating risk
  

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Factors Affecting Risk Perception

• Voluntary vs. Involuntary
• Familiar vs. Unfamiliar
• Visibility of Threat
• Catastrophic vs. Non-catastrophic
• Natural vs. Man-made
• Affects Adults vs. Children
• Trusted vs. Untrusted Communicator
• Equal vs. Unequal Benefits

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TOE OF SWIFT CREEK LANDSLIDE
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Covellos Cardinal Rules of Risk Communication

• Accept and involve the public as a legitimate
  partner
• Plan and carefully evaluate communication efforts
• Identify audience, understand problems, pretest
  message
• Listen to publics specific concerns
• Be honest, frank and open

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Cardinal Rules Continued

• Coordinate and collaborate with other credible
  sources
• Meet needs of media
• Speak clearly and with compassion