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Human Health Risk Assessment and Management

Human Health Risk Assessment and Management. What is Risk Assessment. Scientific approach for evaluating potential for harm from hazardous substances and activities How harmful? How important a priority (comparative risk)? How clean is clean?. Human Health Risk Assessment.

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Human Health Risk Assessment and Management

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  1. Human Health Risk Assessment and Management

  2. What is Risk Assessment • Scientific approach for evaluating potential for harm from hazardous substances and activities • How harmful? • How important a priority (comparative risk)? • How clean is clean?

  3. Human Health Risk Assessment Data Collection and Evaluation/Hazard Assessment Exposure Assessment Toxicity Assessment Risk Characterization

  4. Data Collection and Evaluation • Identify concentrations of contaminants at site • Compare findings to naturally-occurring (background) levels near site • Ensure control samples are not tainted by site activity • Generally exclude low frequency detections (< 5%) in risk assessment

  5. Exposure Assessment • Identify and estimate concentrations of chemicals potentially affecting humans • Characterize the site in terms of: • Physical characteristics • Soil characteristics, surface water location, groundwater (flow depth), meteorology • Exposed populations • Human activities (recreation, residential) • Proximity to release • Potential future uses

  6. Identify exposure pathways • Determine amount of exposure for each pathway using monitoring data or fate and transport models • Analyze concentrations, frequency and duration of contaminant exposure to population groups • Consider characteristics of affected population groups - size of individuals, age, other factors

  7. Toxicity Assessment • Determine whether exposure to certain chemicals results in adverse health effects • Compare dose of contaminant with incidence of adverse human health effect to ascertain relationship • Evaluate available toxicity information • Databases - IRIS • Identify data gaps • Investigate human health problems

  8. Risk Characterization • Combine the results of Exposure Assessment and Toxicity Assessment • Quantify risks to human health from individual chemicals and exposure pathways • Sum risks for various exposure scenarios • Evaluate cancer, non-cancer separately • Describe all assumptions, areas of uncertainty

  9. Risk Assessment versus Risk Management • Risk assessment – unbiased scientific approach to assessing risk • Risk management – incorporates the results of risk assessment, factors in societal values, legal mandates, other considerations • Risk communication typically part of risk management

  10. Communicating Risk • Human response to risk is not always rational • Level of risk play little role in acceptability to public • Emotional response often makes it difficult to communicate risk • People apply personal values when evaluating risk

  11. Voluntary Familiar Natural Affects adults Trusted Equal Benefits Catastrophic Involuntary Unfamiliar Man-made Affects Children Not Trusted Unequal Benefits Not Catastrophic Factors Affecting Risk Perception

  12. Covello’s Cardinal Rules of Risk Communication • Accept and involve the public as a legitimate partner • Plan and carefully evaluate communication efforts • Identify audience, understand problems, pretest message • Listen to public’s specific concerns • Be honest, frank and open

  13. Cardinal Rules Continued • Coordinate and collaborate with other credible sources • Meet needs of media • Speak clearly and with compassion

  14. Arsenic in Drinking Water Case Study

  15. A Bit of Arsenic Regulatory History • Original Public Health Service standard was 50 ug/L • Based on non-cancer endpoints • A variety of human cancers are associated with arsenic ingestion • Lung, bladder, prostate, skin, liver… • High disease levels seen in populations drinking water with arsenic 5-20 times higher than current 50 ug/L MCL (Taiwan study) • Epidemiology, medicine can at best resolve risks >1/100 level • For arsenic, exposures not high enough for epidemiology to find disease in U.S.

  16. Setting the MCL(Sublinear vs Linear Dose-Response) POD approximately 400 ppb X Cancer Arsenic levels in water MCLG=0 ppb

  17. EPA Estimated Cancer Risks from Arsenic Ingestion(FR Notice Page 7008)

  18. PAH Exposure • http://www.atsdr.cdc.gov/HAC/phamanual/appg.html • http://www.epa.gov/iris/subst/0136.htm

  19. Gasworks Park Risk Estimate – Assuming PAH mixture is all BaP Default Soil Intake rates 100 mg/day – Adult 200 mg/day – Child From: http://www.atsdr.cdc.gov/HAC/phamanual/appg.html Note – 4g = 1 Tsp R = ((C x IR x CF) / BW) x RF C = Concentration (mg/kg) IR = Soil Ingestion Rate (mg/day) CF = Conversion factor (10-6 kg/mg) BW = Body weight (kg) RF for BaP = 7.3 / (mg/kg-day) (assumes 25,550 day lifetime) Risk of Soil Ingestion from Hotspot (Acceptable Range 10-4 to 10-6) 50,000 mg/kg x 100 mg/day x 10-6 kg/mg / 70kg x 7.3 kg-day/mg=?

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