Toxicology is the study of poisons and their effects on living organisms. The document traces the history of toxicology from ancient times when poisons were used for hunting, warfare, and executions. It was not until the 16th century that Paracelsus determined specific chemicals were responsible for toxicity. In the 19th century, Orfila described systematic correlations between chemical and biological properties of poisons. The 20th century saw major advances in understanding toxic effects at the molecular level. Toxicology involves studying sources of toxins, sites of toxic action in the body, classifications, and biochemical mechanisms of toxicity.

1. Introduction to
Toxicology
Fasieh ur rehman

2. • History of Toxicology
• Pre history
Poisonous plants and animals were recognized and their extracts used for
hunting or in warfare
1500 BC written records indicate that hemlock, opium, arrow poisons, and
certain metals were used to poisonenemies or for state executions

3. • Post-Classical History
• 1198
With time, people began to make the connection between exposure to a specific
substance and illness or death.
In 1198, Moses Maimonides wrote what may be the first collection of writings on
toxicology, The Treatise on Poisons and Their Antidotes
• Renaissance and Age of Enlightenment
Certain fundamental toxicology concepts began to take shape. Noteworthy studies include
those by Paracelsus in the 16th century and Orfila in the 19th century.
• Paracelsus (16th Century)
Determined that specific chemicals were actually responsible for the toxicity of a plant or
animal poison
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4. •Modern History
Orfila, the founder of toxicology (19th Century)
the first to describe a systematic correlation between the chemical and biological
properties of poisons of the time.
•20th and 21st Centuries
Marked by great advancements in the level of understanding of toxicology.
DNA and various biochemicals that maintain body functions have been discovered.
Our level of knowledge of toxic effects on organs and cells has expanded to the
molecular level

5. •Toxicant
A toxicant is any toxic substance.
covers substances that may be man-made, biologically produced, or naturally occurring.
a toxic agent especially : pesticide
• Toxin
A toxin is an organic poison — it's made by plants and animals. ...
naturally occurring poisons.
toxins your body creates and some that animals and plants excrete
•Toxicity
degree to which a chemical substance or a particular mixture of substances can damage
an organism.

6. Toxican - Poison
logos - Study
Toxicology is a Greek word
(study of poisons)

7. • Toxicology
study of the adverse effects of chemical substances on
living organisms and the practice of diagnosing and
treating exposures to toxins and toxicants

8. • Sources
Chemical source the commonest source e.g. drugs, corrosives
Plant source e.g. hashish and cocaine
Animal source the least but the most serious source. Venomous animals such as
scorpions, snakes, spiders, wasps.

9. • Sites of toxic actions
•Local
wherever the poison contacts the biological system it starts its harmful effects. It
does not require specific site to elicit it effects such as toxicity by acid or alkalis.
• Remote
the poison effects a system far from its portal of entry
•Local and Remote
the poison has the capacity of acting locally and systematically
e.g. oxalic acid

10. • Classification of toxic agents
•According to the target organ they are acting on it (hepatotoxic, nephrotoxic)
•According to their use (food additives, drugs, pesticides)
•According to their source (animal or plant)
•According to their effects (carcinogen, mutagen)

11. •According to their physical state ( gas or liquid)
•According to their chemistry (amine or hydrocarbons)
•According to their poisoning potentiality (extremely toxic, slightly toxic etc.)
•According to their biochemical mechanism of action (alkylating agent, AchE
inhibitor)