Toxic effects of chemical substances

Introduced into the body from outside chemical substance exhibiting the properties of poison and poison only under certain conditions, which are necessary for the expert to a proper understanding of the origin, course and outcome of poisoning. The main of these conditions are the following.
Dose (number) and the concentration of chemical substances. The poison depends on its quantity, entered into an organism. In the same dose injected substance has a therapeutic effect (therapeutic dose), other toxic effects (toxic dose) or results in death (fatal or fatal dose). These doses for many toxic substances can be very different depending on the way the introduction of poison. So, for example, therapeutic dose with the introduction through the mouth can be lethal when receiving a poison directly into the blood.
The same amount of substance, but in different concentrations can have a different effect on the body. So, for example, 100 ml of 96% ethyl alcohol will cause faster and deeper intoxication than the same amount of alcohol entered as 40 % alcohol (vodka) or 6 % (of beer).
The physical state of the substance and its solubility in environments of an organism are essential. Toxic substances may be in solid, liquid and gaseous state. Entered into an organism of a solid chemical act only after their dissolution and absorption in the gastrointestinal tract, so poisoning them occurs much more slowly than in the poisoning of gaseous and liquid substances.
Some toxic chemicals at their reception not have effects in connection with its insolubility in environments of an organism (water, lipids, fats). For example, when x-rays of the gastrointestinal tract is widely used barium sulfate, which is toxic for the human body substances. However, it is not soluble in gastric juice and therefore does not exert its toxic effects. When entering the body carbonate or barium chloride (soluble salts) occurs poisoning.
The speed of absorption and excretion of the poison from the body determines the amount (concentration) of the poison in the body at one time or another poisoning. Therefore, the ratio of these processes largely forms the degree of intoxication.
Related compounds, and chemical impurities introduced into the body together with the poison that can both enhance, and weaken the influence of the latter on the human body. So, for example, contained in ethyl alcohol of an impurity of fusel oils can not only strengthen the ethanol intoxication, but also be crucial in death.
The ways and conditions for the introduction of poison determine the speed of its effect on the organism and the degree of intoxication. The absorption of the poison leads to the appearance in blood. Therefore one and the same concentration of a substance at the introduction into the skin may have a therapeutic effect, and the introduction under the skin into the bloodstream may cause severe toxicity, and even death.
A number of substances is cumulative, i.e. capable to accumulate in the body, - organophosphorus compounds, salts of heavy metals, many drugs. Cumulation inherent in the substances, which are slowly metabolized or bad excreted. So, Foz keep in sublethal doses, the effect of action to 2 days, strychnine, arsenic, methyl alcohol - some day, heavy metals - a few months, and silver and gold - a few years.
The condition of the body and its peculiarities in the period of introduction of poisons in the body. Different people may respond differently to the same poisonous chemical.
Of considerable importance in the individual reaction of organism to influence of chemical substances have the type and condition of the Central nervous system, age, activity of enzyme systems, sex differences, body weight, hormonal activity, nutrition, diseases, physical stress and other
Repeated exposure substances can lead to the development of biological dependence, sensitization and allergic reactions. Biological dependence is manifested in the fact that in long-term use of any drug in a patient develops a need to continue taking it without a medical indication to that. The discontinuation of such substances may be accompanied by the development of severe violations of the physical state (withdrawal syndrome). This dependence can develop when taking many medications morphine, barbiturates and other Established that addictive multidrug due to their ability to accelerate the overall metabolism, causing a kind of "induction" enzymes. This refers to the phenobarbital (luminal), gexobarbitala, meprobamate (meprotan), and other
Allergic reaction to poison occurs when the body has been previously sensitized this or close to it on the chemical structure of a substance. With repeated exposure reacts with the antigen-antibody, manifested in the form typical of allergic syndromes. When drug allergies there is no correlation between the dose of a substance and the degree of manifestation of allergic reactions. Even the least of the drug can cause severe reactions in sensitized the body. From allergies it is necessary to distinguish the idiosyncrasy - genetically determined reaction of the organism to a certain drug. Idiosyncratically effect as toxic, depending on the dose of poison. In practice, to carry out differential diagnosis of intoxication (the toxic effect of poisons in high doses, idiosyncrasies and allergies is not always easy.
Various factors of external environment (cold, heat, noise, ionizing radiation, repeated exposure to chemicals, fluctuations in air pressure and others) may influence the course of intoxication. These and other factors can affect the speed of metabolism, stimulating or, on the contrary, oppressing him.