Toxicity is ... Determination of toxicity

In different industries, and simply in life, one can often hear about poisonous compounds and toxic substances. But what are these molecules like? Toxicity is a measure of virulence or something else? Let's try to understand 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 index. This is a value that indicates how much a compound is dangerous to the health and life of mammals and warm-blooded creatures.

In other words, toxicity is a measure of the maximum permissible concentration of a hazardous substance in which it will not have negative consequences when exposed to living things.

This indicator is calculated as the reciprocal of the average lethal dose of an agent. It can also be said that toxicity is the ability of a compound to cause irreversible changes in the health status of humans, animals or plants.

The measure of toxicity can be different, for its definition, special norms or indicators are used. On this basis, several categories of substances are distinguished.

Classes of toxicity of substances

There are several of them. This is a kind of classification of this concept. We consider all possible groups.

1. The first class of toxicity is extremely harmful. An indication of less than 15 mg / kg of body weight.
2. Highly toxic compounds. Such indicators are higher, but still very small - from 15 to 150 mg / kg.
3. Moderate in action - up to 1500 mg / kg.
4. Malotoxic - more than the previous indicator.

Naturally, the impact on health will not only be the fact which group the aggressor belongs to, but also its time of impact on the body. The higher it is, the greater the risk of death or severe poisoning.

Highly toxic substances

These include not only those that cause poisoning people and animals. But also those that are capable of polluting the environment. They can be in different aggregate states:

• Solid;
• Liquid;
• Gases.

The most dangerous of them are gaseous asphyxiating compounds that do not have color and smell. For example, carbon monoxide or carbon monoxide.

Strong-acting poisonous substances have a number of characteristic features that make it possible to isolate them among other compounds.

1. Capable of being carried by air flows to different (sometimes very large) distances.
2. Settlement on various household items, food and other things, which increases the risk of infection and poisoning.
3. Too great variety of species and differences in characteristics, so that universal protection can be manufactured.

As a result, it turns out that toxicity is a property of a substance with which it is very difficult to cope and even more difficult to fully control. Therefore, work with these connections is extremely dangerous and undesirable. And if it can not be avoided, all possible options for protecting the respiratory tract and skin should be carefully considered.

Consider several examples of the strongest poisons, both among liquids and among strangling gaseous molecules.

Cyanic acid and its salts

The toxicity of substances related to cyanide salts is extremely high. Just like the very connection itself. Its chemical formula is HCN. It has a characteristic only its nature, a smell, easy to move and very volatile.

Its dangerous property is solubility in all types of solvents, including water. Therefore, when ingested, it is absorbed instantaneously. The physiological effect on the body is to block the respiratory system. Cyanides (salts of hydrocyanic acid) are able to bind to the iron of hemoglobin, thereby destroying it. Thus begins the strongest oxygen starvation of all tissues, cells and organs. As a consequence - imminent death or very serious intoxication.

Cyanide potassium has been used as the strongest poison since ancient times. Even then, its properties and effects on the body were known.

Toxic gases

Among the gaseous compounds there are many of those that belong to the group of highly toxic. Even during the First World War, chlorine gas was used as a chemical weapon, and quite successfully.

You can name a few of the most brutal in effect and common compounds of this kind:

• phosgene;
• formaldehyde;
• chlorine;
• Bromine vapor;
• carbon monoxide;
• Phosphorus (III) chloride;
• ammonia;
• Hydrogen sulphide;
• Carbon disulfide;
• Sulphur dioxide;
• Methyl chloride and many others.

It is simply impossible to list all, their number is too large. In addition, all the new varieties of any compounds are constantly synthesized, some of which are replenished by a toxic piggy bank.

Chlorine

It is a poisonous gas of yellow-green color with a suffocating smell. Due to this, it can be detected without special means. He is heavier than air, so he descends into the lowlands. Therefore, to escape from its impact, you need to climb as high as possible.

This error was committed 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 fell. Its biological effect on the body is a strangling effect. Once inside through the respiratory tract, it causes severe tissue burns and, as a result, difficulty breathing, accompanied by pain. This action begins when its concentration in the air in an amount of 6 mg / m ³ .

At the same time, the use of this gas in industry is very important. So, it is used for:

• Production of insecticides;
• Cleaning of metals;
• Food industry as an additive (Е 925);
• Disinfection of water;
• As a bleach additive;
• As a strong disinfectant, including for medical purposes.

Work with this connection should be very careful, using a special protective suit and not disregarding the safety rules.

Phosgene

It is a poisonous gas, which, under normal conditions, does not have a color, but smells of hay. Its most important danger is that there is no antidote against it. You can only protect yourself with a gas mask. It was used in the First World War as a chemical weapon.

Its physiological effect is the instantaneous blocking of the alveolar canals. As a result, there is a strong pulmonary edema. Death becomes inevitable, therefore this gas belongs to the category of extremely toxic substances.

Concentration of it in an amount of only 5 mg can cause a lethal outcome. 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 even at any concentration in the air.