In various industries, and just in life, you can often hear about toxic compounds and toxic substances. But what are these molecules? Is toxicity a measure of toxicity or something else? Let's try to figure it out in the course of the article.
What is toxicity?
According to the chemical point of view, the definition of "toxicity" is a shortened expression of the name of the toxicometric indicator. This is a value that shows how dangerous a particular compound is to the he alth and life of mammals and warm-blooded creatures.
In other words, toxicity is a measure of the maximum allowable concentration of a hazardous substance at which it will not have negative effects when exposed to living beings.
This indicator is calculated as the reciprocal of the average lethal dose of a particular agent. You can also say that toxicity is the ability of a compound to cause irreversible changes in the state of he alth of people, animals or plants.
The measure of toxicity can be different; special norms or indicators are used to determine it. On this basis, several categories of substances are distinguished.
Classessubstance toxicity
There are several of them. This is a kind of classification of this concept. Consider all possible groups.
- The first class of toxicity is extremely harmful. The quantity indicator is less than 15 mg/kg of body weight.
- Highly toxic compounds. For such, the indicator is higher, but still very small - from 15 to 150 mg / kg.
- Moderate in impact - up to 1500mg/kg.
- Low toxicity - more than the previous indicator.
Naturally, he alth will be affected not only by the fact to which group the aggressor belongs, but also by its time of exposure to the body. The higher it is, the greater the risk of death or severe poisoning.
Very poisonous substances
These include not only those that cause poisoning of people and animals. But also those that are capable of polluting the environment. They can be in different states of aggregation:
- hard;
- fluid;
- gases.
The most dangerous of these are gaseous asphyxiant compounds that are colorless and odorless. For example, carbon monoxide or carbon monoxide.
Strong toxic substances have a number of characteristic features that allow them to be distinguished from other compounds.
- Able to be carried by air currents over different (sometimes very large) distances.
- Settling on various household items, food and other things, which increases the risk of infection and poisoning.
- Too bigspecies diversity and difference in characteristics, so that universal protective equipment can be made.
The result is that toxicity is a property of a substance that is very difficult to handle and even more difficult to fully control. Therefore, working with these compounds is extremely dangerous and undesirable. And if it cannot be avoided, then all possible options for protecting the respiratory tract and skin should be carefully considered.
Let's look at some examples of the most powerful poisons, both among liquids and among asphyxiating gaseous molecules.
Prussic acid and its s alts
The toxicity of substances related to hydrocyanic acid s alts is extremely high. Just like the connection itself. Its chemical formula is HCN. It has an odor characteristic only of its nature, is easily mobile and very volatile.
Its dangerous property is solubility in all types of solvents, including water. Therefore, when it enters the body, it is absorbed instantly. The physiological effect on the body is to block the respiratory system. Cyanides (s alts of hydrocyanic acid) are able to combine with hemoglobin iron, thereby destroying it. At the same time, the strongest oxygen starvation of all tissues, cells and organs begins. As a result, inevitable death or very severe intoxication.
Potassium cyanide has been used as a powerful poison since ancient times. Even then, its properties and effects on the body were known.
Poisonousgases
Among the gaseous compounds, there are many that belong to the highly toxic group. Even during the First World War, chlorine gas was used as a chemical weapon, and quite successfully.
Several of the most brutal and common compounds of this kind can be named:
- phosgene;
- formaldehyde;
- chlorine;
- bromine vapors;
- carbon monoxide;
- phosphorus (III) chloride;
- ammonia;
- hydrogen sulfide;
- carbon disulfide;
- sulphurous gas;
- methyl chloride and many others.
It is simply impossible to list everything, their number is too large. In addition, new varieties of any compounds are constantly being synthesized, some of which replenish the treasury of toxic ones.
Chlorine
This is a poisonous yellow-green gas with a suffocating odor. Thanks to this, it can be detected without special tools. It is heavier than air, so it sinks into the lowlands. Therefore, you need to escape from its influence by climbing as high as possible.
This mistake was made by people when they did not know about the properties of this gas. They began to hide in basements and lowlands, where the main cloud of poison descended. Its biological effect on the body is a suffocating effect. Once inside through the respiratory tract, it causes severe tissue burns and, as a result, difficulty breathing, accompanied by pain. This effect begins at its concentration in the air in the amount of 6 mg / m3.
At the same time, the use of this gas in industry is very important. So, it is used for:
- manufacture of insecticides;
- metal cleaning;
- food industry as an additive (E 925);
- water disinfection;
- as a whitening supplement;
- as a strong disinfectant, including for medical purposes.
This compound must be handled very carefully, using a special protective suit and without neglecting safety regulations.
Phosgene
This is a poisonous gas that under normal conditions is colorless and smells like rotten hay. Its greatest danger is that there is no antidote against it. You can only protect yourself with a gas mask. It was used in World War I as a chemical weapon.
Its physiological action is to instantly block the alveolar canals. The result is severe pulmonary edema. Death becomes inevitable, so this gas is classified as extremely toxic.
Its concentration in the amount of only 5 mg can cause death. If from the very beginning of exposure phosgene can be detected by smell, then in the future it blocks the olfactory nerve, so it will not be felt at any concentration in the air.
