Enviromental risk assessment
- 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 4 6