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Wongwiwat TassaneeyakulDepartment of ToxicologyKhon Kaen University

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1) Understand the process of risk assessment.

2) Describe relationship between risk assessment and management.

3) What is the major component in performing risk assessment ?

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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

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RISK DEFINITIONS

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(Morgan 1993).

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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.

 

 

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Actual Number

Scientific Notation

Read As

1/101x10-1

1E-01

One in ten

1/1001x10-2

1E-02

One in a hundred

1/1,0001x10-3

1E-03

One in a thousand

1/10,0001x10-4

1E-04

One in ten thousand

1/100,0001x10-5

1E-05

One in a hundred thousand

1/1,000,000

1x10-6

1E-06

One in a million

1/10,000,000

1x10-7

1E-07

One in ten million

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(NRC, 1983)

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Relationship between risk assessment Relationship between risk assessment and risk managementand risk management

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Step #1Step #1Hazard IdentificationHazard 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

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Cancer risk assessment

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

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Acceptable Daily Intake (ADI)

No observed adverse effect level

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ผลการใช้แบบโมเดลทางคณิ�ตศาสตร�ท��ต�างก�นในการประมาณิข้ามช้�วงมายั�งข้นาดการไดร�บสารพิ�ษ aflatoxin B1 ในข้นาดต&�าๆ ก&าหนดให X = one-hit , M = multistage, W = Weibull, L = logit, G = multi-hit, และ P = probit model ตามล&าด�บ (Lu, 1996).

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Step #3Exposure 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)

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ข้นาดการไดร�บตลอดช้�ว�ต หร*อ LADD (Lifetime Average Daily Dose)

LADD = [(conc. ) * contact rate * contact fraction * expos. duration] [(body weight) * (lifetime)]

HEEEs (high-end exposure estimates)

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Step #4Risk 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 riskassessment characterization results

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Risk Communication

(Raafat & Sadhra, 1999).

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Risk cannot be justified save1:1,000 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