enviro

1. Dr/ Eman Mortada
Associate professor
In public health and preventive medicine
Environmental
Risk assessment

2. The purpose of ERA
Differentiate between Hazards and Risk
Differentiate b/w risk analysis, assessment, management
Risk management
Risk communication
Risk Assessment – how to assess risk
CONTENTS

3. What are Hazards and Risks?
Hazard ≠ Risk
Hazard = Risk

4. A hazard is anything with the potential to cause harm
Hazard ≠ Risk
Risk means Likelihood (chance) that a hazard will cause
a specific harm or injury to person or damage property
Risk = Hazard effect x Probability (likelihood of
Occurrence)

5. Hazard
Risk

6. What is risk assessment?
• Risk Assessment is a systematic approach to identify
hazards, evaluate risk and incorporate appropriate
measures to manage and mitigate risk

7. Risk Analysis
• Risk assessment is part of a larger
evaluation process called risk
analysis, which include
1. Risk assessment
2. Risk management
3. Risk communication
• Risk assessment constitute the
scientific basis of the risk
management process

8. 5- Step in Risk Assessment
1. Hazard Identification
2. Dose-Response Analysis
3. Exposure Analysis
4. Risk Characterization
5. Risk communication

10. Can a specific exposure
cause a specific effect?
Step 1 – hazard identification
Environmental exposure
Disease or Other Outcome

11. Hazard identification
• Specification of exposure
• Process of determining whether
exposure to an agent:
– Can cause an increase in the incidence of a
particular adverse health effect (causality)
Exposure ?? Effect
• Method used in hazard identification
– Review of key research studies and experimental
literature

12. ■ Human studies
 Case reports
 Cluster analyses
 Epidemiologic studies
■ Animal studies
 Specialized tox. studies
 Generalized tox .Studies
■ In vitro studies
Methods Of Identifying Hazards

14. ??Dose Response
How is the identified adverse effect
influenced by
the level of exposure or dose?
Step 2 – dose-response relationship

15. Dose -response relationship
• Dose -response relationship resulting from all available
toxicological or epidemiological studies
• Used to estimate the health hazards of different exposures,
e.g. identify critical value

16. Hypothetical Dose-Response Curve
Showing Determination of the LD50
Dose: amount that enters the body
Response: type & amount of damage caused by a specific dose
Dose-response curves the plot of dose given against response
 Illustrates the effect of different doses on a population
 allow us to predict effects of higher doses.

17. Dose-response curve - alcohol
No effect
Relaxed
Slurred speech
Sleep
Coma
Labored breathing
Death

18. Threshold effects
• Threshold is a level below
which no effect occurs and
above which effects begin
to occur.
– If a threshold exists,
then a concentration
below the threshold is
safe.
– If there is no threshold
dose, then even the
smallest amount has
some negative toxic
effect.

19. Dose-response curve
LD50 = dose
lethal to 50%
of test animals
Threshold = dose at
which response begins
Which one is more toxic???????
A
B
A

20. • LD50
– Lethal dose to 50% of the test
organisms
– The Smaller the LD50, the
more lethal the chemical
– Determined for all new
synthetic chemicals

21. Two Types of
Dose-Response Curves
Fig 17-15

23. ??Agent People
What exposures are
Anticipated
under different conditions?
Step 3 – exposure assessment

24. Exposure
•Environmental exposure: any contact between a
potentially harmful agent present in the medium, and a
surface of the human body

25. The 3 parts of exposure
The Source
Environmental
pathway
The route

26. The 3 parts of exposure
The
Source
of the hazard
(bus exhaust)
The
Environmental
pathway
(air)
The
route
(inhaled fumes)

27. Exposure pathway

28. 28
Inhalation
Route the hazards take

29. 29
Ingestion
Route the hazards take

30. Dermal Absorption
Route the hazards take

31. Exposure assessment
■ What are the routes of exposure?
■ What is the intensity, frequency, and durationof exposure?
The determination of the route, amount, frequency and
duration of exposure → provide an in depth understanding
and overview of the exposure of interest
Exposure = intensity x frequency x duration
Exposure = how much x how often x how long

32. Identification of Exposure Pathways
• Contaminated groundwater – ingestion (drinking water),
dermal contact (bathing), and inhalation of volatile organic
compounds (showering)
• Surface water and sediments – incidental ingestion and
dermal absorption of contaminants (people in bodies of
water)
• Contaminated food – ingestion of contaminated fish tissue,
vegetables and fruit grown in contaminated soil or covered
with contaminated dust, meat, and dairy products

33. • Surface soils – ingestion and dermal absorption of
contaminants by children playing in dirt
• Fugitive dust and VOC emissions – inhalation by nearby
residents or onsite workers
• Subsurface soil and air-borne contaminants – future
land-use conditions during construction activities
• Contaminated breast milk – nursing infants whose
mothers were exposed to highly toxic lipophilic
contaminants
Identification of Exposure Pathways

34. Exposure Routes
• Inhalation (lungs)
– Working environment
– Smoking
– Air pollution
• Ingestion (gastrointestinal)
– Food (additives, microorganisms)
– Dirt (children eat soil)
– Drinking water
• Dermal contact (skin)
– Working environment
– Chemical residues in clothes
– Cosmetics
– Bathing

36. ■ What is the estimated likelihood of the adverse effect
occurring in a given population?
Hazard
identification
Exposure
assessment
Dose-
response
Risk
characterization
Step 4 – Risk characterization
■ Integrate and summarize the hazard identification, exposure
assessment, and dose-response assessment

37. Risk characterization
 Describe the nature and magnitude of risk
 To decide whether the risk from a hazard is significant or
not
 Would it be likely to result in serious or moderate
consequences? Eg a death, a fracture, an amputation or
 Would it be likely to result in minor consequences such as a
small cut to a finger or minor damage to equipment?

38. Consequence
Minor injury or no
apparent injury
Injury requiring
first aid
Injury requiring
medical treatment,
or with possible long
term negative health
effects
L
i
k
e
l
i
h
o
o
d
Will probably not
occur in most
circumstances
Low Low Medium
May occur in
some
circumstances
Low Medium High
Likely to occur in
most
circumstances
Medium High High

39.  If the risk is insignificant, no further action is
necessary, but you should monitor the situation
and encourage your staff to tell you about any
changes.
 If the risk is significant, a High or Medium risk,
you need to complete the rest of the risk
assessment form, detailing the risk and the
control measures needed to reduce it to an
acceptable level.

41. Risk management
 Risk management integrates the
assessment of risk with technical,
legal, political, social, and
economic issues.
 Decide whether or not to reduce or
eliminate risk.
 Weigh costs and benefits

42. What Are Reasonable Control
Measures?
Control measures are things done or action
taken to control or reduce the risks to people’s
safety.
“Reasonable” means that the cost of taking
the action is in proportion to the risk, ie the
higher the risk the higher the cost.
Cost
Risk
cost

43. Control Measures for Reducing Risks

44. Agencies and risk management
Food and Drug Administration (FDA)
• food, additives, cosmetics, drugs, medical
devices
Environmental Protection Agency (EPA)
• pesticides, industrial chemicals, and any
synthetic chemicals not covered by other agencies
Occupational Health and Safety Administration
(OSHA)
• workplace hazards

45. Philosophical approaches
• “Innocent until proven guilty”:
Assume harmless until shown to be harmful
• Precautionary principle:
Assume harmful until shown to be harmless

46. National University of
Malaysia
Risk Assessment & Risk Management?
RISK
PERCEPTION
RISK
ASSESSMENT
RISK
MANAGEMENT
28- Jan-
14
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