Human health risk assessment
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This document discusses human health risk assessment. It defines risk assessment as having two main types - quantitative risk assessment and environmental risk assessment. Environmental risk assessment includes human health risk assessment, where risk is defined as hazard times exposure. The document outlines the process of human health risk assessment, including determining exposure through intake calculations, establishing toxicity values from animal studies with uncertainty factors, and characterizing risk for carcinogenic and non-carcinogenic chemicals by calculating hazard quotients and risk levels. The goal of risk assessment is to properly assess and manage risks to avoid health effects.
Human health risk assessment
- 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 1
- 2. Risk Assessment National University of Malaysia • Risk Assessment in daily life !! 28-Jan-14 2
- 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) • • 28-Jan-14 Ecological risk at sites Risk = hazard x exposure 3
- 4. Quantitative Risk National University of Malaysia • Hazard • Probability RISK in Oil and Gas Industry 28-Jan-14 4
- 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 28-Jan-14 5
- 7. National University of Malaysia Risk Assessment & Risk Management? RISK PERCEPTION 28-Jan-14 RISK ASSESSMENT RISK MANAGEMENT 7
- 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? 8
- 9. Concept of Human Health Risk (1) National University of Malaysia Risk = hazard x exposure 28-Jan-14 9
- 10. National University of Malaysia Concept of Human Health Risk (2) 3 1 2 RISK : Source ------ Pathways ------ Receptors 28-Jan-14 10
- 11. Concept of Source – Pathways - Receptors National University of Malaysia SOURCE RECEPTORS RISK 28-Jan-14 PATHWAYS YES NO NO NO 11
- 12. National University of Malaysia Human Health Risk Assessment (HRA) 1 28-Jan-14 2 12
- 13. National University of Malaysia Oil Well Pump 28-Jan-14 13
- 14. National University of Malaysia Exposure Assessment • Quantify contaminant intake at the point of exposure • Intake = I (Intake) 28-Jan-14 14
- 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) 28-Jan-14 15
- 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 16
- 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 17
- 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 28-Jan-14 18
- 20. No Observed Adverse Effect Level (NOAEL) 28-Jan-14 National University of Malaysia 20
- 21. National University of Malaysia RISK CHARACTERIZATION 28-Jan-14 21
- 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 28-Jan-14 22
- 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 28-Jan-14 23
- 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 24
- 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 28-Jan-14 25
- 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 28-Jan-14 • Use slope factor Calculate Risk for Non-Carcinogenic 26
- 27. Summary (2) 28-Jan-14 National University of Malaysia 27
- 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 28-Jan-14 28
- 29. Computer Software 28-Jan-14 National University of Malaysia 29
- 31. National University of Malaysia Thank you 28-Jan-14 31