What is toxicology ?
Toxicology, poisons leather or leather toxicity studies the effects of toxic chemicals on biological systems. Toxicology is a branch of biology. As far as the impact of toxins on humans, it is a branch of medicine. There are also close links with pharmacology.
Everything is toxic
Paracelsus (Theophrastus von Hohenheim Bombastus 1493-1541) already mentioned in the 16th century "the dose makes the poison", in other words that everything eventually is toxic, if the quantity is large enough. Paracelsus is known as the founder of toxicology. He was the first to put a relationship between dose and toxicity.
The toxicity of a substance can not be measured directly, it can only be set experimentally fixed. What, moreover, is toxic to the one organism, may not be toxic to a different organism. In toxicology used many criteria for toxicity. A known way to determine the toxicity of a substance is the LD50. This represents the lethal dose at which dies 50% of the exposed organisms. This size is dependent upon the organism in which the poison is tested, from the venom itself, the route of administration (for example, absorption through the mouth, through the skin, intravenously or via inhalation) and of the length of the time in which the poison is administered.
Ethical point of view, it is not acceptable to determine the LD50 of substances in humans. Therefore, rats or other laboratory animals are used, but also objections have been raised against them. Today, in vitro toxicology research as possible (in test tubes) done with cell cultures and tissue fragments.
Norms
Toxicological studies are the basis for the standard of theses substances in products. Because the study was not based on humans, it is when setting the standard built-in a safety margin, is often a factor of 10. In some cases, it has been found that people are less sensitive to the toxic effect of a substance. People can, for example, compared with animals remarkably well against dioxins, as showed the attempted poisoning of Ukrainian President Viktor Yushchenko.
Toxic effect
The toxicity of substances arises because the substances act on biochemical reactions in the organism. There are many different toxic effects. Some of the substances are non-toxic on its own, but to be in the organism (e.g., in the liver) is converted to metabolites that do may be toxic.
There are also substances that are not toxic in the chemical sense, but nevertheless can lead to the death of the exposed individual thereto. Thus, it is possible that one gets when drinking concentrated hydrogen peroxide oxygen bubbles in the blood, leading to symptoms similar to the caisson disease.
Some important groups of toxins in effect are:
- Neurotoxins act on the nervous system. Certain poisons which are used by animals to poison their prey fall into this group. The operation of these poisons is acute.
- Are carcinogenic substances enhancing cancer risk: they increase the risk of cancer significantly.
- Mutagenic substances cause mutations in the DNA, possibly leading to deformed offspring.
- Teratogenic substances cause malformations in embryos, sperm and egg cells.
Environmental toxicology
When it comes to environmental toxicology research on the effect of chemicals on ecosystems. Also, based on this type of research standards are drawn up by the government.
Cumulative effects
- Toxicology also investigates the combined effect of different substances. Two substances need not separate from each other (heavy) to be toxic, but can be toxic or mixed with each other if they have a pharmacological interaction with each other.
- Toxicology also examine the effects of prolonged exposure to toxic substances not known but it can affect the metabolism in the long run. She examines whether for instance flame retardants in electronics, softeners in plastics and food additives in the long run lead to bioaccumulation potential health problems.