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Toxicology& Risk Analysis. Sumol Pavittranon, Ph. D. Dept. Of Medical Sciences [email protected] 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

Toxicology& Risk Analysis

Sumol Pavittranon, Ph. D.

Dept. Of Medical Sciences

[email protected]

slide2

RISK

EXPOSURE

standards

DOSE

SENSiTIVITY

Extrapolate

Testing

slide3

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)

slide4

ความไม่รู้เป็นพิษที่สุดความไม่รู้เป็นพิษที่สุด

“ Ignorance is the most toxic of all”

Sumol Pavittranon

slide5

Toxic Agents

  • Chemicals
  • Food additives
  • Drugs
  • Pesticides
  • Metals
  • Solvents
  • Radiation
  • Toxin
  • Pollutants
slide6

Principle of toxicology

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

slide7

Factors influence risk estimate

  • Chemical property
  • Biological System
  • Effect or response
  • Exposure situation
slide8

Toxicity Testing

  • Acute toxicity
  • Subacute toxicity
  • Chronic toxicity
  • Reproductive toxicity
  • Genotoxicity
  • Neurotoxicity
  • Immunotoxicity
slide9

Acute toxicity testing

  • 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
slide10

Sub chronic testing

  • 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
slide11

Chronic toxicity testing

  • 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
slide12

Animals

Rodent and non-rodent

Avain

Fish

Aquatic invertibrate

Ferret

non primates

dog

rabbit

slide13

Reproductive toxicity testing

  • Reproductive efficiency, 2 generation
  • Fertility profile 70 days
  • Semen analysis
  • Pathology, gross and histo
  • Oogenesis
  • In vitro method
  • Teratogenetic
  • Biochemistry parameters
slide14

Genotoxicity testing

  • Gene mutation assay (Ame’s assay)
  • Chromosome effect
  • Sister chromatic exchange
  • Micronucleus test
  • DNA interaction (DNA unscheduled synthesis)
  • Neoplastic cell tranformation
  • BALB/3T3 cells
slide15

Neurotoxicity testing

  • Condition behaviors
  • Unconditioned behaviors
  • Affective behaviors
  • Social behavior
  • Motor acts
  • Learning & Memory
  • Biochemical
  • NTE
  • cAMP, cGMP
  • GABA
  • Dopamines
slide16

Immunotoxicology testing

Immune disfunction

increase tumor susceptability

decrease host resistance

slide17

Dose response Relationship

Assumptions

Response vary concentration

Concentration vary dose

dose related to response

slide18

Low level risk estimate

One-hit model

Linear

Multistage

Weibull

Multihit

Logit

Probit Model

slide19

NOEL

NOAEL

LOEL

LOAEL

Critical Points

* NOAEL = No Observed Adverse Effect Level

* End Point / การเกิดพิษ

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

* Exposure

slide20

Public Hearing

Risk Assessment

Risk Management

Risk Communication

Public

Policy formulation

Standards / Implimentation

slide21

Data submission for registration

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

slide22

Environmental Toxicology

Emission

Control

Transport

Monitor

Human response

slide23

Environmental Toxicology

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

slide24

“The Toxicologist may be able

to assess the risk of a compound,

but an acceptable risk level

will be set by the public”

slide25

References

  • 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
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