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6143511 Wongwiwat Tassaneeyakul Department of Toxicology Khon Kaen University.

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Presentation on theme: "6143511 Wongwiwat Tassaneeyakul Department of Toxicology Khon Kaen University."— Presentation transcript:

1 Wongwiwat Tassaneeyakul Department of Toxicology Khon Kaen University

2 ) Understand the process of risk assessment. 2) Describe relationship between risk assessment and management. 3) What is the major component in performing risk assessment ?

3 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


5 (Morgan 1993).

6 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.

7 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 9 (NRC, 1983)

10 Relationship between risk assessment and risk management

11 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

12 Cancer risk assessment

13 Step #2 Dose-Response Assessment "The dose makes the poison."

14 Acceptable Daily Intake (ADI ) No observed adverse effect level


16 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).

17 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)

18 ขนาดการได้รับตลอดชีวิต หรือ LADD (Lifetime Average Daily Dose) LADD = [(conc. ) * contact rate * contact fraction * expos. duration]  [(body weight) * (lifetime)] HEEEs (high-end exposure estimates)

19 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

20 Risk Communication (Raafat & Sadhra, 1999).

21 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

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