Poison and Poisoning Azwin bin Md Tumin National Poison Centre - - PowerPoint PPT Presentation

Poison

and

Poisoning

Azwin bin Md Tumin

National Poison Centre

Outline

• a. Definition
• b. Forefathers of toxicology
• c. Famous poisoning cases
• d. Misconception about poisoning
• e. Basic principles of poisoning

f. Factors influencing toxic effects

• g. Take home points

Definition

• Poison:

Substance that, taken into or formed within the organism, impairs the health of the organism and may kill it.

• Poisoning:

Intoxication, morbid condition produced by a poison.

• Toxicology:

Scientific discipline involving the study

• of the actual or potential danger presented by the harmful effects of

substances on living organisms and ecosystems,

• of the relationship of such harmful effects to exposure, and
• of the mechanisms of action, diagnosis, prevention and treatment of

intoxications.

• Source: IUPAC Glossary, Environmental Health and Toxicology, US Dept of Health &

Human Services

Definition

• Toxic agent is anything that can produce an adverse

biological effect. It may be chemical, physical, or biological in form.

• Toxic agents may be:
• Chemical (such as pesticides, pharmaceuticals)
• Biological (such as snake venom, mushroom)
• Physical (such as radiation)

Forefathers of Toxicology Paracelsus (~1500AD)

• Specific chemicals are

responsible for the toxicity of a plant or animal poison.

• Small doses of a

substance might be harmless or beneficial whereas larger doses could be toxic

• Dose-response

relationship, a major concept of toxicology.

Orfila (~1800 AD)

• Father of toxicology
• Prepared a systematic

correlation between the chemical and biological properties of poisons of the time

Famous Poisoning Cases

Misconception about poisoning

• Poison ≠ Antidote
• Poisoning ≠ Antidote administration
• Amount/Level ≠ Effect of poison
• Poison ≠ Measurable in biological sample
• Natural compounds ≠ safe compounds
• Synthetic agents ≠ toxic agents ‡

Basic principles of poisoning

• All substances are poisons; it is

the dose that makes the poison (Paracelsus)

Basic principles of poisoning

• Dose-response relationship
• Establishes causality that the chemical has in fact induced

the observed effects

• Establishes the lowest dose where an induced effect occurs –

the threshold effect

• Determines the rate at which injury builds up - the slope for

the dose response.

Basic principles of poisoning

• Dose estimates (LD50)
• Dose-response curves are used to derive dose estimates of

chemical substances. A common dose estimate for acute toxicity is the LD50(Lethal Dose 50%). This is a statistically derived dose at which 50% of the individuals will be expected to die. (from animal study)

Factors Influencing Toxic Effects

• Form and innate chemical activity
• Dosage, especially dose-time relationship
• Exposure route
• Species
• Age
• Sex

Factors Influencing Toxic Effects

• Ability to be absorbed
• Distribution within the body
• Metabolism
• Excretion
• Presence of other chemicals

• NOT every poison has its own antidote
• NOT every poisoning case needs antidote

administration

• LD50 is the dose at which 50% of the population

affected expected to die

• Several factors influencing toxic effects includes form,

dosage, exposure route, age, species, sex & pharmacokinetic parameters

Take Home Points

References

• 1. Introduction to Toxicology, CHEST Training Package

for the Health Sector, European Commission (EU) retrieved from http://ec.europa.eu/health/ph_projects/2003/action3/d

• cs/2003_3_09_a21_en.pdf
• 2. Toxlearn - Module 1: Introduction to Toxicology and

Dose-Response retrieved from https://toxlearn.nlm.nih.gov/Module1.htm

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