The field of Toxicology

Toxicology aims to evaluate the study of the harmful effects of chemicals on living organisms, with a view of the risks of exposure to these substances for humans, animals and the environment and to minimize undesirable effects. Toxicology is an interdisciplinary field between the medical, biological and chemical fields of science.

 

The "study of poisons", or toxicology, is a discipline at the interface of chemistry (chemistry) and biology. A toxicologist studies the harmful effects that chemicals ("poisons") may have on living organisms. Toxicology originated already in ancient Greece. The Greek government used poison made from plants in order to adminster them to convicts on death row. A well-known example is the execution of Socrates (399 BC v) by means of a plant extract.

Figure 1:  Drinking the cup of poison by Socrates (Jaques Louis David, 1787).







However, many centuries passed before toxicology as a discipline evolved. The main founder of modern toxicology is Paracelcus (1493-1541) (Figure 2).

He was the first to make a direct correlation between the dose of a substance and the symptoms of poisoning. His most famous statement "the dose makes the poison", everything is toxic if the dose is high enough, is quoted to this day by teachers during introductory lectures in toxicology.

 

A well-known but somewhat outdated unit to express toxicity is the LD50. This is the dose killing 50% of the exposed organisms. Obviously it is not possible to determine the LD 50 value of a substance with people, hence, it is used instead in test animals such as rats and mice. However, experimental animal research often has include safety factors, as laboratory animals and humans may be differently susceptible to toxic substances. For example, people can tolerate a much higher concentration of dioxin than laboratory animals, as was recently witnessed during the poisoning by dioxin of President Victor Yushchenko.



Figure 3: Viktor Yushchenko before (left) and after dioxin poisoning (right).







However, more attention is now given to the ethical treament of test animals and more emphasis is being put on in vitro research. In in-vitro research, experiments are carried out with tissues or cells in test tubes.

 

A very recent development in toxicology is toxicogenomics research. This may, with advanced techniques, determin the effect of toxic substances at the level of thousands of genes at the same time. A major advantage of this technique is both the saving of laboratory animals, as well as providing a mechanistic understanding of the effects of substances. It is the hope of many scientists that the latter technique in combination with other in vitro techniques, end or drastically reduce the use of animals.


Figure 4: In toxicogenomics, the activity of thousands of genes upon exposure to toxins is measured as colored dots.

Nowadays toxicology has many sub-disciplines such as environmental toxicology, genetic and reproductive toxicology, occupational toxicology, pharmaceutical toxicology, food toxicology and medical / forensic toxicology.

 

 

In addition to environmental toxicology, which is often in the news such as with the new dioxin scandal, medical and forensic toxicology often plays a role in the television program "Crime Scene Investigation" (CSI). In the Netherlands, forensic toxicology investigations are conducted at the Dutch Forensic Institute (NFI) in The Hague.

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