Throughout life, each person is faced with a large number of chemicals that have an effect on health and vital functions, both through direct contact and remotely (after a certain period of time). Currently classified about seven million different compounds. Of these, over sixty thousand are used by man in his activities. Each year, the world is replenished with a thousand or more “new products” - chemicals or mixtures that can exert the most diverse effects on living organisms.
Talk about using chemicals
If we classify chemicals (and talk about their dangers) in the light of practical use, we can list the following groups:
1. Poisons, the scope of which is industrial production. We are talking about dyes (aniline), solvents (dichloroethane), fuel (butane, propane), etc.
2. Pesticides used in agriculture.
3. Household chemicals (meaning sanitary detergents, as well as food additives and everything that is used for personal hygiene).
4. Poisons of biological origin (obtained from plants or animal organisms).
5. Substances of toxic effect (examples - mustard gas, phosgene, etc.)
Each of these chemicals is able to affect the human body, penetrating through the skin, getting into the respiratory system or ending up on the mucous membranes. Any of the substances is characterized by both a general toxic effect and selective exposure. For example, poisoning with lead compounds adversely affects reproductive function, exposure to nickel and chromium leads to the growth of malignant tumors, nitric oxide can lead to pulmonary edema, and cobalt salts are fraught with cardiological toxic effects.
About general toxic effects
There is a national standard (GOST 53856-2010), which provides a breakdown of chemicals into categories relative to the target. Each of the groups, in turn, consists of subgroups corresponding to the hazard class of substances of a particular chemical type. If we talk about acute toxic effects, there are only five of these classes. Each of the chemicals corresponds to an indicator that depends on the average lethal dose (its designation in the tables is DL50).
According to this standard, substances of hazard class 1 are chemical elements, a small amount of which is enough to defeat with a probability of 50% of the body of a toxic nature or in the form of an inhalation effect (steam, gas or dust). Specific concentration figures in appropriate units can be found in a special table.
Hazard class 2 substances are those chemicals that lead to similar effects if ingested, but at a higher concentration. The third and fourth classes include substances whose exposure indicators are higher than the threshold in the first and second categories. The fifth class consists of elements with a concentration above 5000 units, in connection with the use of which there is evidence of the death of experimental animals or deep toxic damage or very serious poisoning.
In experiments to study the degree of danger, a substance acted on the body for a certain period (four hours).
About the effect on the skin
Another classification is based on the ability to affect human skin and cause necrosis of its skin. The criteria by which all chemical products are divided are two. The first classification method divided all substances into three categories. The first and second of them include those chemicals whose consequences are visible significant necrosis of the skin or reversible damage that lasts up to two weeks.
The third hazard class of substances, according to this classification, includes products that can cause slight irritation, lasting no more than two days. There is another classification method, which is used when it is impossible to attribute a chemical substance to one or another category due to the lack of data.
Impact on the organs of vision
GOST classifies elements causing skin necrosis as the first hazard class of substances. Here are those substances, as a result of the use of which irreversible changes in the ocular apparatus occur. That is, we are talking about persistent visual impairment. Further, according to the above GOST, it is said about the second class of hazard of chemicals. These are the elements that cause a change in the organs of vision of a pathological nature that can go away within 21 days.
Impact on water and the environment
There is a classification of hazardous chemicals according to the degree of harmful effects on human nature in the standard mentioned above. This group includes elements that can destroy the ozone layer, which have increased toxicity in the aquatic environment. In the second case, it is a chronic toxic effect on the aquatic environment together with its inhabitants, that is, delayed exposure (gradual poisoning).
Each of the subgroups of chemicals, in turn, is divided into three categories, in which everywhere the first hazard class is the most toxic and harmful.
Classification of hazards by properties
Elements are divided into various groups, including according to their inherent chemical and physical properties. In this section, we are talking about explosives: gases under pressure, flammable gases, substances in aerosol packaging, flammable liquids, flammable solids, self-decomposing materials, pyrophoric (that is, capable of spontaneous ignition in direct contact with air) substances, self-heating materials, oxidizing substances (that is, gases that ignite other substances upon contact with them), as well as chemicals that emit flammable gases in contact with water and organic their peroxides, causing corrosion of metals.
The standard states that each chemical element can be assigned to a certain hazard class of substances in different categories. For example, a particular gaseous substance can be classified as a gas under pressure, an oxidizing element, a substance with the potential for acute toxic effects, a substance that causes tissue necrosis, and an element that can have an acute toxic effect on the surrounding aquatic environment.
International standards
Another classification of hazards into categories was adopted on the basis of the European Treaty concerning the transport of dangerous goods. It was signed in 1957 in Geneva. In addition to him, there are also other agreements regarding the transportation of dangerous and toxic elements by air, by rail and by sea.
Dangerous goods include contents that can cause harm to human life and health, as well as environmental objects as a result of an accident. We give a brief generalized classification according to which all substances are divided into 9 groups. Each category is limited by its own rules regarding transportation and storage.
Class 1. This includes chemicals that are capable of explosion either with a low probability of explosion, have a high risk of ignition, or may be slightly sensitive to explosion and fire. From this point of view, the most dangerous elements are those that can respond to any external mechanical impact in the form of shock, friction or spark, or the influence of another substance. The molecular structure of highly explosive chemicals is highly unstable and easily moves.
Class 2. According to an international treaty, gases in the compressed or liquefied form, or under pressure, are classified in this category. According to their characteristics, they can be flammable, poisonous, chemically stable, flammable and poisonous, without the danger of fire and not toxic. However, there are certain criteria regarding gas pressure at a certain temperature.
Class 3. The following category refers to the list of hazardous liquids or their mixtures with a flammable character. The hazard class 3 substances, in turn, is divided into three different types depending on the temperature at which ignition occurs.
Class 4. This category consists of materials and substances in the solid state of aggregation, also capable of ignition. This hazard class of substances in the same way consists of a number of categories - materials that can easily ignite under external influence and burn for a long time, substances with self-ignition properties, elements emitting hazardous gases. That is, substances of hazard class 4 - any solid materials with the above characteristics.
Class 5. It consists of organic peroxides that produce oxygen and can cause an explosion or combustion. Oxidizing agents are very dangerous in case of interaction with other substances due to the possibility of hazardous chemical reactions.
Other hazard classes of harmful chemicals
Class 6. This includes elements that constitute the greatest danger to health and life. These are toxic substances that can cause severe poisoning or even death (as a result of inhalation of vapors or when the element comes into contact with the skin or mucous membrane). This, in the sixth hazard class of substances, also includes substances that contain the most dangerous microorganisms. Moreover, the main criterion for such materials is the possibility of infection with an infectious disease.
Class 7. It includes substances with harmful radioactive radiation.
Class 8. It consists of elements with high causticity in contact with human skin or with metal. The effect exerted by such material is almost always irreversible.
Class 9. This includes all other materials and substances that are not included in any of the previous classes. Each of the representatives in this category can become dangerous in certain circumstances. As such factors that trigger the mechanism of manifestation of harmful and dangerous nonspecific properties, one can name high temperature (60-100 degrees), etc.
What other classification systems exist?
There are tables that subdivide substances according to their strength. Considering examples of various chemicals actively used by people, each of them can be attributed to one or another hazard class. For example, acetone and fuel are ranked in the fourth class, methyl alcohol in the third, nickel, chlorine, sulfuric acid in the second, and lead in the first.
How to protect yourself from harmful effects?
To minimize the risk of exposure to chemical factors on the environment and people, the following methods are used:
1. Sources of hazardous industrial wastes should be located away from workplaces.
2. Hazardous compounds must be removed in a timely manner by ventilation systems.
3. Workers in hazardous and hazardous work must necessarily use special personal protective equipment for skin and respiratory organs. The latter are divided into two main types - insulating and filtering. We are talking about gas masks, respirators and filtering self-rescuers. To the insulating type are gas masks, the work of which is based on bound oxygen.
It is possible to protect the aquatic environment through the rational organization of water intakes and drains, reducing the concentration of harmful chemicals to acceptable limits, treating effluents, and observing the rules established by SanPiN 2.1.4.1017-01 to ensure the quality of drinking water.