Hazardous Chemical Substances (HCS)

A harmful chemical substance is a substance that, upon contact with the human body, in case of violation of safety requirements, can cause diseases or abnormalities in the human body.

Harmful substances in industry can be part of the raw materials, final, by-products or intermediate products of a particular production. They can be of three types: solid, liquid and gaseous. Formation of dust of these substances, vapors and gases is possible.

VCV can enter the human body through the respiratory, digestive, and skin. Vapors, gaseous and dusty substances enter through the respiratory tract, mainly liquid substances through the skin. Harmful substances enter the gastrointestinal tract when they are swallowed or put into the mouth with contaminated hands.

Liquid harmful substances most often seep through leaks in equipment, communications, splash when they are openly drained from one container to another. At the same time, they can get directly on the skin of workers and have a corresponding adverse effect, and in addition, pollute the surrounding outer surfaces of equipment and fences, which become open sources of their evaporation. With such pollution, large evaporation surfaces of harmful substances are created, which leads to rapid saturation of the air with vapors and the formation of high concentrations. The most common causes of leakage of liquids from equipment and communications are corroding gaskets in flange connections, loose taps and valves, insufficiently sealed glands, metal corrosion, etc.

If liquid substances are in open containers, evaporation also occurs from their surface and the resulting vapors are introduced into the air of working premises; the larger the open surface of the liquid, the more it evaporates.

In the case when a liquid partially fills a closed container, the resulting vapors saturate the empty space of this container to the limit, creating very high concentrations in it. If there are leaks in this container, concentrated vapors can enter the workshop atmosphere and pollute it. The vapor output increases if the container is under pressure. Massive vapor emissions also occur at the time of filling the container with liquid, when the liquid being poured displaces accumulated concentrated vapors from the container, which enter the workshop through the open part or leaks (if the closed container is not equipped with a special air outlet outside the workshop). The release of vapors from closed containers with harmful liquids occurs when opening lids or hatches to monitor the progress of the process, mix or load additional materials, take samples, etc.

If gaseous harmful substances are used as raw materials or obtained as finished or intermediate products, they, as a rule, are released into the air of working premises only through accidental leaks in communications and equipment (since if they are present in the apparatus, the latter cannot open even for a short time ).

The source of the release of harmful substances of all three types (aerosol, vapor and gas) are often various heating devices: dryers, heating, roasting and melting furnaces, etc. Harmful substances in them are formed as a result of combustion and thermal decomposition of certain products. Their release into the air occurs through the working openings of these furnaces and dryers, leaks in their masonry (burnouts) and from the heated material removed from them (molten slag or metal, dried products or fired material, etc.).

Substances that are highly soluble in fats and lipoids can enter the bloodstream through intact skin. Severe poisoning is caused by substances that have increased toxicity, pungency, and rapid solubility. These include, for example, nitro and amino products, aromatic hydrocarbons, tetraethyl lead, methyl alcohol, etc.

Toxic substances in the body are distributed unevenly, and some of them are capable of accumulating in certain tissues.

Here, electrolytes can be especially distinguished, many of which very quickly disappear from the blood and are concentrated mainly in the organs. Lead accumulates mainly in the bones, manganese – in the liver, mercury – in the kidneys and colon. Naturally, the peculiarity of the distribution of poisons can, to some extent, be reflected in their further fate in the body.

The toxic effect of certain harmful substances can manifest itself in the form of secondary lesions, for example, colitis in case of arsenic and mercury poisoning, stomatitis in case of lead and mercury poisoning, etc.

The danger of harmful substances to humans is largely determined by their chemical structure and physicochemical properties.

Environmental conditions can either enhance or weaken the effect.

So, at elevated air temperatures, the danger of poisoning increases; poisoning with amido and nitro compounds of benzene, for example, occurs more frequently in summer than in winter. High temperature also affects the fluidity of the gas, the rate of evaporation, etc. It has been established that air humidity enhances the toxicity of some poisons (hydrochloric acid, hydrogen fluoride).

Most industrial poisons cause both acute and chronic poisoning. However, some toxic substances usually cause the development of a predominantly second (chronic) phase of poisoning (lead, mercury).

According to the toxic (harmful) effect of exposure to the human body, substances are divided into groups:

1. General toxic chemicals (hydrocarbons, alcohols, hydrogen sulfide, mercury salts, carbon monoxide, etc.) – They cause nervous system disorders, muscle cramps, and affect blood-forming organs.

2. Irritants (chlorine, ammonia, sulfur dioxide, nitrogen oxides, etc.). They affect the mucous membranes, upper and deep respiratory tract.

3. Sensitizing substances that act as allergens (aldehydes, solvents and varnishes based on nitro compounds). Increase the body’s sensitivity to chemicals.

4. Carcinogenic substances (benzapyrene, asbestos, aromatic amines, etc.). Causes the development of all cancers.

5. Mutagenic substances (ethylene oxide, chlorinated hydrocarbons, lead, mercury compounds, etc.). They affect the germ cells, which affects the next generation.

6. Chemicals affecting human reproductive function (boric acid, ammonia, manganese, nicotine, etc.).c Cause birth defects.

The last three types of exposure to harmful substances – carcinogenic, mutagenic, effects on reproductive function, as well as the acceleration of the aging process of the cardiovascular system, are referred to as separate consequences of the influence of chemical compounds on the body. This is a specific action that appears in remote periods, years and even decades later. The appearance of various effects in subsequent generations is also noted.

Protection against harmful substances

– control over the content of harmful substances in the air of the working area;

-use of PPE;

– normal functioning of heating, ventilation, air conditioning systems, purification of emissions into the atmosphere;

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