Presentation on theme: "6143511 Wongwiwat Tassaneeyakul Department of Toxicology Khon Kaen University."— Presentation transcript:
Wongwiwat Tassaneeyakul Department of Toxicology Khon Kaen University
) Understand the process of risk assessment. 2) Describe relationship between risk assessment and management. 3) What is the major component in performing risk assessment ?
the capacity of a substance to cause an adverse effect in a specific organ or organ system the probability that a hazard will occur under specific exposure conditions The definition of risk is: the weighing of policy alternatives and selection of the most appropriate regulatory actions
How are risks measured and expressed? Risks are measured by direct observation or by applying mathematical models and a series of assumptions to animal data to infer risk to humans.
Actual Number Scientific Notation Read As 1/101x E-01One in ten 1/1001x E-02One in a hundred 1/1,0001x E-03One in a thousand 1/10,0001x E-04One in ten thousand 1/100,0001x E-05 One in a hundred thousand 1/1,000,0001x E-06One in a million 1/10,000,0001x E-07One in ten million
9 (NRC, 1983)
Relationship between risk assessment and risk management
Step #1 Hazard Identification In this initial step, Information is gathered and analyzed in a weight-of-evidence approach. Data usually consist of: human epidemiology data animal bioassay data supporting data
Cancer risk assessment
Step #2 Dose-Response Assessment "The dose makes the poison."
ผลการใช้แบบโมเดลทางคณิตศาสตร์ที่ต่างกันในการประมาณข้าม ช่วงมายังขนาดการได้รับสารพิษ aflatoxin B1 ในขนาดต่ำๆ กำหนดให้ X = one-hit, M = multistage, W = Weibull, L = logit, G = multi-hit, และ P = probit model ตามลำดับ (Lu, 1996).
Step #3 Exposure Assessment characterization of the exposure setting (e.g., point source, occupational source) identification of exposure pathways (e.g., groundwater) quantification of the exposure (e.g., µg/L water)
Step #4 Risk Characterization •Review toxicity and exposure assessment output •Quantify risks •Combine risks across all pathways •Assess & present uncertainties •Consider site-specific human studies, if available •Summarize & present baseline risk assessment characterization results
Risk Communication (Raafat & Sadhra, 1999).
Risk cannot be justified save 1:1,000 per person/year 1:10,000 per person/year Tolerable only if risk reduction is impracticable or if its cost is grossly disproportional to the gain 1:1,000,000 per person/year Unacceptable region The ALARP (As low as reasonably practicable) or tolerable region Broadly acceptable region 1:10 million per person/year Necessary to maintain assurance that risk remains at this level Risk Communication