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8/18/2019 Introduction of Risk Assessment
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Module Three
Introduction to Risk
Assessment
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Objectives
Upon completion of this module, you will be able to:
Define and understand the concept of risk
Identify and discuss the steps involved in performing a
risk assessment
Understand the roles of risk assessment and riskmanagement
Understand the role of ATSDR’s public health assessment
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What is Risk Assessment?
Gathering of information on toxic effects ofa chemical
Evaluation of information to determine
possible risks associated with exposure
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Risk Assessment Process
1. Hazard Identification
2. Hazard Evaluation or Dose-Response
Assessment
3. Exposure Assessment
4. Risk Characterization154
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Hazard Identification
Collection of data Various sources
Toxicological and epidemiological studies
Information should answer these questions:
Does exposure to the substance produce any adverseeffects?
If yes, what are the circumstances associated with the
exposure?
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Hazard Identification (continued)
Name of Substance Physical/Chemical properties of substance
Source of the toxicity information
Epidemiological Studies
Toxicological Studies
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Hazard Identification (continued)
Exposure to toxic substances1. Route
2. Duration
3. Frequency
Other Factors which may affect results
1. Diet
2. Lifestyle choices
3. Occupation157
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Hazard Evaluation or
Dose-Response Assessment
Purpose of evaluation
Calculate the dose-effect
Include “safety factor”
Purpose of assessmentDetermine what dose causes a response
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Exposure Assessment
Exposure means contact at a boundary between a human and the environment at aspecific contaminant for a specified period
of time.
Exposure Assessment
Identifies affected population
Calculates the amount, frequency, length oftime, and route of exposure
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Exposure Assessment (continued)
Outline General Information for Each Chemical
Sources
Exposure Pathways and Environmental Fate
Measured or Estimated Concentrations
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Exposure Assessment
General Information
Physical/chemical properties
How it is transported
How it is accumulated in the environment and
in tissue
How it is transformed when it is released
These facts determine the dose and route of exposure
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Exposure Assessment
Sources of Exposure
Exposure can occur
Inside the home (cleaning products, paints,
pesticides)
Outside the home (pollutants in air)
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Exposure Assessment
Exposure Pathways and Environmental Fate
After source identification, route and natureof the exposure have to be determined.
Example:
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Exposure through drinking water
Route is ingestion of contaminated water
E A t
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Exposure Assessment
Measured or Estimated
Concentrations
Measured concentrations areobtained from actual samples of the
source of exposure
Estimated concentrations are used
when samples are not available, andare based on a mathematical model
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Exposure Assessment
Measurement of Exposure
Questionnaires/surveys
Employment records
Evaluation of environmental contamination
data
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Approaches for Assessing
Total Exposure
Indirect Methods Environmental monitoring
Fate and transport (migration) computer models
Resident questionnaires/surveys
Direct Methods Personal workplace monitoring
Biologic markers
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Exposure Assessment
Assessing Health Disparities by Determining the proximity of communities to
waste or industrial facilities
Characterizing the nature and extent ofexposures
Identifying susceptible populations
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Factors Which Influence the Extent
of Exposure
Size of population
Proximity of the community to source of
contamination
Degree of personal contact with site
Extent of release of substances
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Other Characteristics to Include in
Exposure Assessments
Possible health effects from exposure tosimple and complex mixtures
Health impact on susceptible populations
Geographic area
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ifi i f
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Identification of Exposed
Populations
Identify and characterize
Sex
Age
Number of children Number of pregnant women
Number of chronically ill individuals
Number of individuals with higher risks Personal habits
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Children’s Susceptibility
to Exposure
Primary Routes of Exposure
Ingestion
Play Activities Inhalation
Breathing rates
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R t P bl i
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Recurrent Problems in
Exposure Assessment
Absence of actual data
Lack of personal monitoring
Inaccurate exposure assessment
Lack of documentation indicating exposure
amount and dose
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R P bl i E
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Recurrent Problems in Exposure
Assessment (continued)
Determining Causal Relationships
Exposure and health outcomes
Disparities in health status
Lack of published research
Inconsistent data related to exposure and health
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Recurrent Problems in Exposure
Assessment (continued)
Limited use of epidemiological methods
Association of low level exposure and disease
Studies of adverse effects
Differentiation of populations
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Information A ailable for Risk
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Information Available for Risk
Assessments
Occupational exposure
Lung Disease dusts
silica dusts
coal
Lung Toxicity heavy metals
carcinogens
Neurotoxic Effects
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Additional Components of the
Risk Assessment
Calculation of Exposure
Risk Characterization
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Risk Management
• Determines the best approach to address
an exposure issue
• Evaluates data from risk assessment
• Evaluates other issues
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Question and Answer Period
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