Toxicology is defined as the study of poisons and its effect on
organisms especially with the humans. It is also concerned with the study of
the symptoms, mechanisms, treatment and detection of poisoning. A poison is any substance which has adverse
effects upon exposure.
Major disciplines of Toxicology
- 1. Mechanistic – mimics the biochemical and cellular effects of toxins. Studies from this field provide a foundation for rational therapy design and development of tests aimed to assess degree of exposure of poisoned human.
- 2. Descriptive- uses results from animal experiments to see what level of exposure will cause damage to humans, this process is otherwise known as risk assessment.
- 3. Forensic- this is concerned in medicolegal consequences of toxin exposure
- 4. Clinical – deals with interrelationship of toxins to diseases.
*Other areas include: Aquatic , Chemical, Ecotoxicology, Environmental toxicology, and Medical toxicology.
Toxin Exposure
From a clinical point of view, exposure to toxins occur due to
suicide(50%), accidents(30%) and the remaining percentage to occupational
hazards and even homicide. Accidental exposure occurs more commonly among children
and suicide-induced exposure produces the highest mortality rate.
Routes
- 1. Ingestion- most commonly seen in clinical setting
- 2. Inhalation
- 3. Transdermal
Although harm produced by poisoning is due to poisons, other
factors must be taken into consideration. One of the key factors in identifying
the effect of poison is its dose. In toxicology,
any substance can cause harm if given at the correct dosage, this includes
water. The dose of toxin is positively correlated to its effect. Although death
is the most severe effect of poisoning, some toxins when given at small amounts
can produce pathologic effects.
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| Dose-Response Relationship Photo Credit: http://www.fao.org/docrep/009/a0238e/A0238E26.gif |
Many agents have been encountered that can produce toxic effects
to humans but here are some non-drug agents which are commonly encountered and
presents medical emergencies in acute exposure:
- Alcohol
- Carbon Monoxide
- Caustic agents
- Cyanide
- Metals and metalloids
- Pesticides
Here are some therapeutic drugs that are most commonly seen in
overdose:
- Salicylates
- Acetaminophen
Laboratory Testing
In most cases, analysis of toxic agents is a two-step manner:
- Screening- rapid, simple, qualitative
- Confirmatory- example is Thin Layer Chromatography
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| Thin Layer Chromatography Photo Credit: http://www.waters.com/webassets/cms/category/media/other_images/primer_b_%20thinlayer.jpg |
References:
Clinical Chemistry: Techniques, Principles, Correlations
by: Bishop, Fody, Schoeff
http://www.news-medical.net/health/Toxicology-What-is-Toxicology.aspx
