슬라이드 노트

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슬라이드1

Definition of Risk Total risk = (How much or How often)                        x (Some risk per unit of action, or per event) Risk = Probability(Exposure) x Severity(Toxicity)             = S{probability x severity x weight}     : Likelihood(probability) that an adverse event will occur when a product  containing a hazardous chemical is used in permitted ways Measures of Risk  : Deaths, Injuries, et al. Risk Assessment : The determination of the probability that an adverse effect will result from a defined exposure

Elements of the Risk Assessment and Risk Management Processes (NAS, 1983)

An Environmental Health Paradigm and Its Relationship to the Risk Assessment Framework  (Adapted from Sexton et al., 1995)

Hazard Identification Toxicity data - Carcinogenicity       - Acute/Subchronic/Chronic Toxicity - Mutagenicity       - Teratogenicity / Developmental Toxicity - Reproductive toxicity       - Systematic Toxicity - NOAEL(No observed adverse effect level) - LOAEL(Lowest observed adverse effect level) Environmental fate and transport Example of Useful database IRIS (Integrated Risk Information System) : EPA, USA HSDB (Hazardous Substances Data Bank) : NIH, USA

Dose-response Assessment What is the relationship between dose and incidence in human? Extrapolation Experimental Dose(High Dose) to Low-Dose(Environmental Dose) Using Mathematical model Dose-Scaling Animal Dose to Human Dose Considering body weight, surface area, et al.

General approaches to deriving toxicity criteria based on toxicological end-points Approach

Reference Dose Reference Dose (RfD) or  Reference Concentration (RfC) the estimate of the amount of a substance in food or drinking-water, expressed on a body weight basis UF : Uncertainty Factors   3-10, from animals to humans    3-10, human variability        5-10, less than chronic data 5-10, LOAEL instead of NOAEL      10, incomplete data base Modifying factor   1< MF <10

Estimation of Benchmark Dose(BMD)

Graphical presentation of data and extrapolation - cancer potency (slop factor) -

Graphical presentation of data and extrapolation - Margin of Exposure (MOE) -

Exposure Assessment

Example) Exposure Pathways for Power Plant or Incinerator -

Basic Equation for exposure dose estimation                         EC x IR  x AF x EF x ED     Dose =                        BW x AT x 365(days/year) Dose = exposure intake ( mg/kg bw-day ) EC = the environmental concentration IR = daily intake or contact rate AF = absorption factor EF =  exposure frequency ED = exposure duration BW = body weight(kg) AT = averaging time : for evaluation of carcinogens – 70 years for evaluation of non-carcinogens – duration of exposure

Risk Characterization Non-carcinogen Hazard Index  = [exposure level] / [reference dose] Exposure and reference dose Carcinogen linear low-dose model Risk  = CDI(chronic daily intake average developing cancer x CP(cancer potency) one-hit model Risk = 1-exp(CDI x SF) Aggregate Risks for multiple substances : sum of individual risk Combining risks across exposure pathways : sum of exposure by all pathways

Uncertainty Analysis - Monte-Carlo Simulation -

Risk Assessment and Risk management

Block diagram illustrating the process involved in risk assessment and management

Differential Impact of Trust-Increasing and Trust-Decreasing Events

Schematic Representational of Understandings of Risk Among Non-Experts

Maximum Individual Risk as a Function of Risk Categories

Flow chart for the generalized assessment process