Risk assessment process

FATHER OF MODERN TOXICOLOGY
PARACELSUS—1564
“All things are Poisonous,
only the dose makes it non-poisonous.”
Dose alone determines toxicity
All chemicals—synthetic or natural—have the capacity
to be toxic
Dose
THE KEY CONCEPT in Toxicology
www.SlideShare.net/AhmedRefat
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LEARNING OBJECTIVES
By the end of this presentation you will be able to:
1. Develop a basic understanding of risk
assessment and its role within the risk
management process.
2. Differentiate between risk assessment and risk
management.
3. Develop a basic understanding of how to
conduct and evaluate an uncertainty analysis
for a risk assessment
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RISK ASSESSMENT
Ecological Risk
Assessment
Human Health Risk
Assessment.
Dr. Ahmed-Refat AG Refat
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RISK ASSESSMENT PROCESS
The systematic
characterization of potential
adverse health effects
resulting from human
exposure to hazardous
agents
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WHAT IS A HAZARD?
Something that
has the potential to cause harm
to people, property or the
environment.
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WHAT IS RISK?
The likelihood that the
harm from a particular
hazard is realised,
and is a function of
hazard and exposure.
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WHAT IS SAFETY ?
Safe means ―without risk‖.
There is usually no such thing
as zero risk
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ACTIVITIES IN HUMAN
1. Planning for RAP
2. Four Steps of RAP
3. Risk Management
4. Risk Communication
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ACTIVITIES IN HUMAN
1. Planning for RAP
3. Risk Management
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PLANNING A HUMAN HEALTH RISK
ASSESSMENT
 Risk assessors will typically ask the
following questions when planning a
human health risk assessment:
1. Who/……………………
2. What/…………………..
3. Where is at risk?.....
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PLANNING ………………..
Who.………………... is at risk?
Individual
General population
Lifestages such as children,
teenagers, pregnant/nursing women
Population subgroups - highly
susceptible and/or highly exposed .
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PLANNING ………………..
What is a risk?.....
 Chemicals (single or multiple/cumulative risk)
 Radiation
 Physical (dust, heat)
 Microbiological or biological
 Nutritional .
 Socio-Economic ( for example, access to
health care)
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PLANNING …………
Where is the risk?
 Point sources (for example, smoke or
water discharge from a factory;
contamination from a Superfund site)
 Non-point sources (for example,
automobile exhaust; agricultural runoff)
 Natural sources
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PLANNING ……………….
How does exposure occur?
 Pathways :
 Air-Surface Water-Groundwater-Soil-Solid Waste-
Food
 Non-food consumer products, pharmaceuticals
 Routes :
 Ingestion (both food and water)-Contact with skin
 Inhalation- Non-dietary ingestion (for example,
"hand-to-mouth" behavior)
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PLANNING ………….
What are the health effects?
 cancer,
 heart disease,
 liver disease
 nerve disease.
 ……………
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PLANNING ………..
How long?
Acute - within a few hours to a day
Subchronic - weeks or months (for
humans generally less than 10% of their
lifespan)
Chronic - a significant part of a lifetime or
a lifetime (for humans at least 7 years)
Intermittent
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ACTIVITIES IN HUMAN
1. Planning for RAP
3. Risk Management
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The four main risk assessment activities are:
 1.Hazard identification
 2.Dose-response assessment
 3.Exposure assessment
 4.Risk characterization
 Exposure: any condition which provides an
opportunity for an external environmental agent
to enter the body
 Dose: the amount of agent actually deposited
within the body
 Response: the biological effect of the agent.
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 1.Hazard identification
 −Characterize the innate toxic effect of the agent
 2.Exposure assessment
 −Measure or estimate the intensity, frequency, and
duration of human exposure to the agent
 3.Dose-response assessment
 −Characterize the relationships between varying doses
and incidences of adverse effects in exposed populations
 4.Risk characterization
 −Estimate the incidence of health effects under the
various actual conditions of human exposure
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HAZARD IDENTIFICATION
 Human studies
 −Case reports
−Cluster analyses
−Epidemiologic studies (Causality)
 􀂄 Animal studies
 􀂄 In vitro studies
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2. DOSE-RESPONSE ASSESSMENT
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 Two Types of ―Traditional‖ Dose-Response
Relationships
 Graded or continuous dose response
 Quantal or categorical dose response
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 1. Graded or Continuous Dose Response
 Reflects a dose-dependent increase in severity
of response
 Applies to continuous variables Body weight, etc.
 Blood/serum enzyme activity
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QUANTAL RESPONSES
all or none responses in a population
(responders and non-responders)
Response of a population –
specific end points
% individuals with tumors, % individuals dead
Quantal responses can best be explained in terms
of a probability distribution
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QUANTAL RESPONSES
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NON-TRADITIONAL DOSE RESPONSE CURVES
U-shaped dose response –
essential nutrients ,
hormones/hormonally active
chemicals; various other
chemicals
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3. EXPOSURE ASSESSMENT
 􀂄 Where is the agent found?
 􀂄 What are the routes of exposure?
 􀂄 How many people are exposed?
 􀂄 Who is exposed?
 􀂄 What is the intensity, frequency, and
duration of exposure?
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4. RISK CHARACTERIZATION
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4. RISK CHARACTERIZATION
 􀂄 Integrate and summarize the hazard
identification, exposure assessment, and dose-
response assessment
 􀂄 Develop public health risk estimates
 􀂄 Develop a framework to define the
significance of the risk
 􀂄 Present assumptions, uncertainties, and
scientific judgements
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RISK ASSESSMENT UNCERTAINTIES
Great deal of uncertainty is inherent in the exercise
Due to uncertainty and the desire to protect human
populations, risk assessments are generally conservative
and overestimate risk
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SAFETY (UNCERTAINTY) FACTORS FOR RISK
ASSESSMENT OF NON-CANCER EFFECTS
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RFD = REFERENCE DOSE
Estimated daily dose that is likely to
have no appreciable adverse effects
during a lifetime exposure.

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EXPOSURE LIMIT FOR BENZENE
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RISK MANAGEMENT
The process of weighing policy
alternatives and selecting the most
appropriate regulatory action based
on the results of risk assessment
and social, economic, and political
concerns
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RISK MANAGEMENT
 Risk assessment establishes whether a
risk is present and, if so, the range or
magnitude of that risk.
In the risk management process, the
results of the risk assessment are
integrated with other considerations,
such as economic or legal concerns, to
reach decisions regarding the need for
and practicability of implementing
various risk reduction activities.
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RISK MANAGEMENT
Risk managers also use risk
assessment results as a basis
for communicating risks to
interested parties and the
general public.
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RISK MANAGEMENT DECISION FRAMEWORK
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 To select the preferred option, the
potential positive and negative effects
associated with each option may be
considered under the following headings :
Technical factors:
Economic factors:
Environmental security:
Social issues:
Organisational capabilities:
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RISK COMMUNICATION
The process of making risk
assessment and risk management
information comprehensible to
lawyers, politicians, judges, business
and labor, environmentalists, and
community groups (public)
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THANK YOU
 http://www.epa.gov/risk_assessment/hazardo
us-identification.htm
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Risk assessment process

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