Environmental Risk Assessment, Human health risk assessment, environmental

1. National University of
Malaysia
Human Health Risk Assessment
Wan Zuhairi Wan Yaacob (Assoc. Prof, PhD)
Faculty of Science and Technology
National University of Malaysia
43600 Bangi, Selangor, MALAYSIA.
28-Jan-14
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2. Risk Assessment
National University of
Malaysia
• Risk Assessment in daily life !!
28-Jan-14
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3. 2 types of Risk Assessment
National University of
Malaysia
1. QRA – Quantitative Risk Assessment
–
Risk = Likelihood x consequences
2. ERA – Environmental Risk Assessment
a) Human Health Risk Assessment (HRA)
•
•
•
Health related risk
Risk = hazard x exposure
(i) carcinogenic (ii) non-carcinogenic chemicals
Fukushima Daiichi
nuclear disaster
b) Ecological Risk Assessment (ERA)
•
•
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Ecological risk at sites
Risk = hazard x exposure
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4. Quantitative Risk
National University of
Malaysia
• Hazard
• Probability
RISK in Oil and Gas Industry
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5. Risk Assessment
National University of
Malaysia
• Risk of particular event =
probability of that event to occur x
consequence of the event
• Consequence = damage to people,
property, economic activity, public
service, etc)
• Large earthquake: low probability but
high consequence
• Acceptable risk
– Minimum risk that people can
accept
– Eg. Driving a Car
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6. National University of
Malaysia
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7. National University of
Malaysia
Risk Assessment & Risk Management?
RISK
PERCEPTION
28-Jan-14
RISK
ASSESSMENT
RISK
MANAGEMENT
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8. Risk Assessment (Risk Matrix)
National University of
Malaysia
E = Extreme risk; H = High Risk; M = Medium Risk; L = Low Risk
Example:
• Risk of travelling by car in Malaysia?
• Risk of travelling with an aeroplane
nowadays?
28-Jan-14
Example
• Risk of volcanic eruption in Malaysia?
• Risk of earthquake in Japan?
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9. Concept of Human Health Risk (1)
National University of
Malaysia
Risk = hazard x exposure
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10. National University of
Malaysia
Concept of Human Health Risk (2)
3
1
2
RISK : Source ------ Pathways ------ Receptors
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11. Concept of
Source – Pathways - Receptors
National University of
Malaysia
SOURCE
RECEPTORS
RISK




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PATHWAYS








YES
NO
NO
NO
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12. National University of
Malaysia
Human Health Risk Assessment (HRA)
1
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2
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13. National University of
Malaysia
Oil Well Pump
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14. National University of
Malaysia
Exposure Assessment
• Quantify contaminant intake at the point of
exposure
• Intake = I
(Intake)
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15. Exposure Assessment
National University of
Malaysia
The General Equation for chemical intake is:-I = C x CR x EFD
• I = intake (mgkg-1d-1)
-------------– Mg/kg body weight per day
BW x AT
• Chemical related variable, C
– Chemical concentration; the average concentration contacted over the
exposure period (eg, mg/L water or mg/kg soil or PPM)
• Variables that describe the exposed population
– CR = contact rate; the amount of contaminated medium contacted per unit
time or event (eg. Litres/day)
– EFD = exposure frequency and duration, describes how often and how long
exposure occurs. Often calculated using two terms (EF & ED)
– EF = exposure frequency (days/year)
– ED = exposure duration (years)
– BW = body weight; the average body weight over the exposure period (kg) –
70kg (Adult 70kg ; infant (5 kg) ; children (10kg)
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16. National University of
Malaysia
Exposure Assessment
•
28-Jan-14
I = C x CR x EFD
-------------BW x AT
Assessment-determined variable
– AT = averaging time OR total exposure time; period over which exposure is
averaged (days)
– (1) For evaluation of carcinogenic effects, AT = life expectancy for population
of concern (70 years in US) x 365 days/year
– (2) For evaluation of non-carcinogenic effects, AT = ED x 365 days/year
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17. National University of
Malaysia
Toxicity values
• Animal studies
Rats
Uncertainty
factor(UF) or
safety factor
(SF)
Uncertainty
factor(UF) or
safety factor
(SF)
Toxicity value for
human
Feeding, inhalation testing
Cancer slope factor (SF)
Reference dose (RfD)
28-Jan-14
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18. Toxicity values for Carcinogens
National University of
Malaysia
• Use slope factor (y = mx)
• There is no threshold
because exposure to any
level of a carcinogenic
chemical poses a probability,
however small, of generating
carcinogenic response.
• The curve passes through
the origin
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19. National University of
Malaysia
(mg/kg/day)-1
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20. No Observed Adverse Effect Level (NOAEL)
28-Jan-14
National University of
Malaysia
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21. National University of
Malaysia
RISK CHARACTERIZATION
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22. Determination of non-carcinogenic risk
National University of
Malaysia
• Represented by Hazard Quotient (HQ); the ration of
chronic daily intake to RfD:
HQ = I / RfD
•
•
•
•
HQ = hazard index (dimensionless)
I = the intake (TDI, mgkg-1d-1)
RfD = reference dose (mgkg-1d-1)
HQ <1.0 = acceptable risk for all contaminants and
routes of exposure
• HQ>1.0 = the receptors are exposed to the
contaminant
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23. Determination of non-carcinogenic risk
National University of
Malaysia
• Acceptable Non-Cancer Hazard Quotient (or
Hazard Index)
– US Superfund NCP codified acceptable HQ of 1
– DOE Malaysia (2009); HQ = 1 ; DOE = CLMCG No 2
– US Clean air Act; HQ =1
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24. Determination of carcinogenic risk
National University of
Malaysia
• Carcinogenic risk is a function of the chronic daily
intake (CDI – chemical intake) and the slope factor
(SF):
US: RISK = CDI x SF
• Risk is the probability of carcinogenic risks
(fractions); unitless; IELCR = incremental Excess Lifetime Cancer
Risk
• CDI or lifetime average daily dose= daily intake
(CDI, mgkg-1d-1) -- exposure
• SF = carcinogenic slope factor (mgkg-1d -1) -1
28-Jan-14
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25. Acceptable cancer risk levels
National University of
Malaysia
• US State RBCA Target Risk Policies: 10-5 to 10-4
for development of risk based soil and
groundwater cleanup standards.
• US Clean Air Act : risk 10-4
• Malaysia (DOE, 2009) : 1/10000 to 1/1,000,000
@ 10-4 to 10-6
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26. National University of
Malaysia
Summary (1)
RISK OF CHEMICAL OF CONCERN
EXPOSURE TO HUMAN
• Inhalation
TOXICITY OF CHEMICAL
• Carcinogenic
• Non-Carcinogenic
• Ingestion
• Contact
• Use NOAEL
Calculate Risk
for Carcinogenic
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• Use slope factor
Calculate Risk for
Non-Carcinogenic
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27. Summary (2)
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National University of
Malaysia
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28. Conclusions
National University of
Malaysia
- Risk is always present
- Risk can be assessed (calculated)
- Risk can also be managed properly
to avoid any health effect / accidents
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29. Computer Software
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National University of
Malaysia
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30. National University of
Malaysia
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31. National University of
Malaysia
Thank you
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