What is toxicology?
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

The science of poisons.
The study of poison in living organism.
The study of adverse effects of poisons (chemical agents e.g. drug, lead,
mercury or physical agents e.g. radiation) on living organisms.
Toxicologist: who studies or works in the area of toxicology.

Paracelsus determined that specific chemicals were actually responsible for the
toxicity of a plant or animal poison.

He also said: "all substances are poisons; there is none which is not a poison.
The right dose differentiates a poison and a remedy".

Orfila; the father of modern toxicology or the founder of toxicology.

Orfila was the first person that prepared a systematic correlation between the
chemical and biological properties of poisons of the time.

He demonstrated the effects of poisons on specific organs by analyzing
autopsy materials for poison and their associated tissue damage.
On high doses of:

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
Paracetamol: toxic effect on the liver.
Ibuprofen: bleeding of GI tract.
Clostridium tetani: affecting the CNS and neurotoxic due to the release of
tetanus.
Xenobiotics: foreign substances taken into the body.
Xenobiotics are classified into:
A. Beneficial (e.g. Pharmaceuticals).
B. Toxic
(e.g. lead, mercury).
Substance
Beneficial
Toxic
Lethal
Alcohol
(Ethanol blood level)
0.05 %
0.1 %
0.5%
Carbon monoxide
(% of HB bound)
< 10 %
20-30 %
> 60%
Secobaraital
(sleep Aid)
0.1 mg/dl
0.7 mg/dl
> 1 mg/dl
Aspirin
0.65 gm (2 Tab.)
9.75 gm (30 Tab.)
34 gm (105 Tab.)
Ibuprofen
400 mg (2 Tab.)
1400 mg (7 Tab.)
12,000 mg
(60 Tab.)
Note: alcohol at small doses is beneficial; because it will increase the HDL.
What are the differences between the toxicant, toxin and poison?
Toxicant:
Toxin:
It's a substance that
produces an adverse
effects, it may be
chemical or physical,
which may produce
effects either acute
or chronic.
Proteins produced by living
organisms e.g. Clostridium
tetani microorganism which
produces
tetanus
toxin
(cause Neurotoxicity). The
toxins produce immediate
effect (acute). Mushrooms
are another example.
Poison:
It's a toxicant which causes
immediate death or illness when
experienced
in
very
small
amounts.
The toxic agent:
-
Anything which produce adverse biological effects.
It can be chemical (e.g. cyanide), physical (e.g. radiation) or biological (e.g.
snake venom).
It can be made of a single material or a mixture of many toxic materials.
Toxicology specialized areas:
A. Forensic toxicology: hybrid of analytical chemistry and fundamental
toxicological principle.
B. Clinical toxicology: doctor who is specialized in studying toxicology.
C. Environmental toxicology: impact of chemical and pollutant in the environment
on the biological system (e.g. Radiation).
D. Eco-toxicology: it's specialized within the environmental toxicology and focus
on the impact of a toxic substance on population which act dynamically on the
Eco-system.