In various industries, and just in life, you can often hear about toxic compounds and toxic substances. But what kind of molecules are they? Is toxicity a measure of toxicity 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 a toxicometric indicator. This is a value that shows how dangerous a particular compound is for 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 at 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 state of health 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.
Toxicity classes
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 is less than 15 mg / kg of weight.
- Highly toxic compounds. In such cases, the indicator is higher, but still very small - from 15 to 150 mg / kg.
- Moderate in exposure - up to 1500 mg / kg.
- Low toxicity - more than the previous indicator.
Naturally, the health effect will be exerted not only by the fact to which group the aggressor belongs, but also by his time of exposure to the body. The higher it is, the greater the risk of death or severe poisoning.
Potent 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 aggregate states:
The most dangerous of these are gaseous asphyxiating 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.
- They are able to be carried by air flows over different (sometimes very large) distances.
- Settling on various household items, food and other things, which increases the risk of infection and poisoning.
- Too much species diversity and difference in characteristics for universal protection products to be made.
The result is that toxicity is a property of a substance that is very difficult to cope with and even harder to completely 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 a few examples of the most powerful poisons, both among liquids and among suffocating gaseous molecules.
Hydrocyanic acid and its salts
The toxicity of substances related to hydrocyanic acid salts is extremely high. Just like the compound itself. Its chemical formula is HCN. It has a smell peculiar only to its nature, is easily mobile and very volatile.
Its dangerous property is solubility in all types of solvents, including water. Therefore, when ingested, it is absorbed instantly. The physiological effect on the body is to block the respiratory system. Cyanides (salts of hydrocyanic acid) are able to combine with the hemoglobin iron, thereby destroying it. At the same time, severe oxygen starvation of all tissues, cells and organs begins. As a result - imminent death or very severe intoxication.
Potassium cyanide has been used as the strongest poison since ancient times. Even then, its properties and effects on the body were known.
Toxic gases
Among gaseous compounds, there are many 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 some of the most cruel in action and common compounds of this kind:
- phosgene;
- formaldehyde;
- chlorine;
- bromine vapor;
- carbon monoxide;
- phosphorus (III) chloride;
- ammonia;
- hydrogen sulfide;
- carbon disulfide;
- sulphur dioxide;
- methyl chloride and many others.
It is simply impossible to list everything, their number is too large. In addition, ever new varieties of any compounds are constantly being synthesized, some of which replenish the toxic piggy bank.
Chlorine
It 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 impact 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 asphyxiating 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 it is concentrated in air in an amount of 6 mg / m 3 .
Moreover, the use of this gas in industry is very important. So, it is used for:
- making insecticides;
- metal cleaning;
- food industry as an additive (E 925);
- water disinfection;
- as a bleaching additive;
- as a strong disinfectant, including for medical purposes.
Work with this connection very carefully, using a special protective suit and not neglecting safety regulations.
Phosgene
This is a poisonous gas that, under normal conditions, has no color, but smells like pretty hay. His main danger is that there is no antidote against him. You can protect yourself only with a gas mask. It was used in the First World War as a chemical weapon.
Its physiological effect is to instantly block the alveolar channels. As a result, severe pulmonary edema occurs. 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, therefore it will not be felt even at any concentration in the air.