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Toxicology& Risk Analysis. Sumol Pavittranon, Ph. D. Dept. Of Medical Sciences sumol@dmsc.moph.go.th. RISK. EXPOSURE. standards. DOSE SENSiTIVITY. Extrapolate. Testing. Toxicology. “All substances are poisons; there is none which is not a poison.

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Toxicology risk analysis l.jpg

Toxicology& Risk Analysis

Sumol Pavittranon, Ph. D.

Dept. Of Medical Sciences

sumol@dmsc.moph.go.th


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RISK

EXPOSURE

standards

DOSE

SENSiTIVITY

Extrapolate

Testing


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Toxicology

“All substances are poisons;

there is none

which is not a poison.

The right dose differentiates

a poison and a remedy.”

Paracelsus (1493-1541)


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ความไม่รู้เป็นพิษที่สุดความไม่รู้เป็นพิษที่สุด

“ Ignorance is the most toxic of all”

Sumol Pavittranon


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Toxic Agentsความไม่รู้เป็นพิษที่สุด

  • Chemicals

  • Food additives

  • Drugs

  • Pesticides

  • Metals

  • Solvents

  • Radiation

  • Toxin

  • Pollutants


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Principle of toxicologyความไม่รู้เป็นพิษที่สุด

Obtaining, gathering data

to predict or hypothesize what happen

in the future to man and the environment

To do risk extrapolation

Safety assesment

Regulatory control


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Factors influence risk estimateความไม่รู้เป็นพิษที่สุด

  • Chemical property

  • Biological System

  • Effect or response

  • Exposure situation


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Toxicity Testingความไม่รู้เป็นพิษที่สุด

  • Acute toxicity

  • Subacute toxicity

  • Chronic toxicity

  • Reproductive toxicity

  • Genotoxicity

  • Neurotoxicity

  • Immunotoxicity


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Acute toxicity testingความไม่รู้เป็นพิษที่สุด

  • Adverse effect within 24 hr

  • Life threatening, accidental, overdose

  • Define intrinsic toxicity of the chemical

  • Oral, dermal, inhalation, skin, eye irritation

  • Define LD50

  • LD50= Dose that cause 50 % mortality


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Sub chronic testingความไม่รู้เป็นพิษที่สุด

  • Repeated dose for up to 6 months

  • 10 % life span

  • 2 spp, rodent and non-rodent

  • reflect cumulative effect, latent period

  • and reversibility

  • non-lethal parameter

  • target organ arranged

  • Data for chronic study


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Chronic toxicity testingความไม่รู้เป็นพิษที่สุด

  • Life span of animal, 2 year in rat

  • 18 months in mice

  • Similar metabolism in man

  • Same route of administration

  • Exposure duration similar to man

  • 3 treatment groups

  • Maximum tolerated dose

  • Pathology data, bl. chem, urianalysis

  • Good Laboratory practice

  • To define safety factor


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Animalsความไม่รู้เป็นพิษที่สุด

Rodent and non-rodent

Avain

Fish

Aquatic invertibrate

Ferret

non primates

dog

rabbit


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Reproductive toxicity testingความไม่รู้เป็นพิษที่สุด

  • Reproductive efficiency, 2 generation

  • Fertility profile 70 days

  • Semen analysis

  • Pathology, gross and histo

  • Oogenesis

  • In vitro method

  • Teratogenetic

  • Biochemistry parameters


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Genotoxicity testingความไม่รู้เป็นพิษที่สุด

  • Gene mutation assay (Ame’s assay)

  • Chromosome effect

  • Sister chromatic exchange

  • Micronucleus test

  • DNA interaction (DNA unscheduled synthesis)

  • Neoplastic cell tranformation

  • BALB/3T3 cells


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Neurotoxicity testingความไม่รู้เป็นพิษที่สุด

  • Condition behaviors

  • Unconditioned behaviors

  • Affective behaviors

  • Social behavior

  • Motor acts

  • Learning & Memory

  • Biochemical

  • NTE

  • cAMP, cGMP

  • GABA

  • Dopamines


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Immunotoxicology testingความไม่รู้เป็นพิษที่สุด

Immune disfunction

increase tumor susceptability

decrease host resistance


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Dose response Relationshipความไม่รู้เป็นพิษที่สุด

Assumptions

Response vary concentration

Concentration vary dose

dose related to response


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Low level risk estimateความไม่รู้เป็นพิษที่สุด

One-hit model

Linear

Multistage

Weibull

Multihit

Logit

Probit Model


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NOEL ความไม่รู้เป็นพิษที่สุด

NOAEL

LOEL

LOAEL

Critical Points

* NOAEL = No Observed Adverse Effect Level

* End Point / การเกิดพิษ

* Uncertainty Factors (1, 5, 10, 100, 1000)

* Exposure


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Public Hearingความไม่รู้เป็นพิษที่สุด

Risk Assessment

Risk Management

Risk Communication

Public

Policy formulation

Standards / Implimentation


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Data submission for registrationความไม่รู้เป็นพิษที่สุด

Toxicological data

Mechanistic data

Epidemiological data

Exposure data

Efficacy data

NOAEL

Reference dose (Rfd, ADI )

Carcinogenic potency

Adverse health

effect

Total exposure

Margin of safety

Risk (MRL, TI, )

-Public health policy

-Socio-economics

-Politics

Decision making

Further data

required

Rejection

Approval

Post-marketing

monitoring and surveillance

Reassessment

Reassessment


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Environmental Toxicologyความไม่รู้เป็นพิษที่สุด

Emission

Control

Transport

Monitor

Human response


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Environmental Toxicologyความไม่รู้เป็นพิษที่สุด

Water Pollution

Ecology parameters

Parameters

BOD

Physical property

Total solids

Oil & grease

Metals

Free Chlorine

Phosphate

Sulfide

Nitrogen

Bacteria

Environmental Exposure Data

Octonal/ Water Ratio

Environmental fate

Aquatic toxicity

Bioaccumulation

Sensitivity and

High risk group


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“The Toxicologist may be able ความไม่รู้เป็นพิษที่สุด

to assess the risk of a compound,

but an acceptable risk level

will be set by the public”


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Referencesความไม่รู้เป็นพิษที่สุด

  • Principles and Methods of Toxicology

    • A. Wallace Hayes, Student Edition

  • Casarett and Doull’s Toxicology: The basic Sciences of Poisons

    • J. Doull, C. D. Klaassen, and M. O. Amdur

  • Human Health and the Environment

  • US Dept of Health, Education, and Welfare,

  • DHEW Publication # NIH 77-1277