Poor-quality food products contaminated with overtime impurities can cause food poisoning of microbial origin, various infectious diseases and helminthiasis.
Chemical substances in the human body are carried by blood and distributed in organs, tissues and cells. The amount of chemicals that accumulate in the body depends on their distribution in tissues and cells, the microclimate, the method of introduction and exposure, age, sex, and other factors. Due to the body’s resistance, most chemicals and their metabolites are excreted in feces, urine, exhaled air, sweat through the skin, and saliva and breast milk.
The toxicity of chemical substances is characterized by its absolutely lethal dose – the minimum dose at which the studied animals die, as well as the average lethal dose at which 50% of them die. The lethal dose of a chemical substance is expressed in milligrams per kilogram of body weight. Foreign substances are very dangerous for the child’s body, when the physiological protective barriers have not yet formed sufficiently, as well as for nursing women.
Chemical substances can accumulate in the body and show the effect of summation, when the negative effect of one substance is added to the effect of another. These properties are characteristic of many substances and depend on their chemical and physical properties (solubility in water and fats, etc.). Chemical substances can be deposited in the liver, brain, adrenal glands and other organs. Organic compounds of zinc, silver, and other fat-soluble metals can affect the central nervous system.
In the process of metabolism of toxic substances, new substances can be formed, the poisonous effect of which is stronger compared to the substances that entered the body. Thus, when parathion is introduced after aldrin, paraoxon is formed, the toxicity of which is much higher. The action of some organophosphorus compounds is weakened if phenobarbital or chlorcycline is first introduced into the body.
Chemical substances that enter the body with food can cause cancer of the stomach and intestines. Mineral oils and aromatic amines, epoxy resins, lactones, peroxides and some aliphatic organic compounds are carcinogenic. They cause cancer of the skin, bladder and other organs. Chemical carcinogenic compounds also include 3, 4-benzpyrene, 2-acetylaminofluorene, 4-dimethylaminoazobenzene, ethyl carbonate, tetrachloromethane, etc. Nitrosodimethylamine and other nitrosamines are often found in foods.
Mycotoxins, which are life products of some lower fungi and plants, have a harmful effect on animals and humans. They cause the disease ergotism, which is accompanied by convulsions, hallucinations, etc. This disease occurs in case of consumption of bread baked from flour, which has been contaminated with the products of life of lower fungi.
All chemicals are toxic if they enter the body in significant quantities. Even harmless substances, if they are used in large doses, can have an adverse effect with undesirable consequences. More than 75% of all diseases are caused by chemical carcinogens that enter the body through inhaled air, food and drink. Carcinogenic compounds of arsenic are especially dangerous – gases, pesticides, cosmetics, tobacco, etc.
Harmful are substances that, when in contact with the human body under the conditions of violation of safety requirements, can lead to industrial injury, occupational disease or health disorders, which are determined by modern methods both in the work process and in the distant lifetime of current and future generations (GOST 12.1.007-76)?
Harmful substances can enter the human body through respiratory organs, digestive organs, as well as skin and mucous membranes. Vapors, gaseous and dust-like substances enter through the respiratory tract. Through the gastrointestinal tract, substances enter during swallowing, or when they are introduced into the oral cavity with contaminated hands.
The main route of entry of industrial harmful substances into the human body is the respiratory tract. Thanks to the huge (more than 90 m2) suction surface of the lungs, favorable conditions are created for harmful substances to enter the blood.
Harmful substances that have entered the body in one way or another can cause poisoning. The degree of poisoning depends on the toxicity of the substances, the time of action, the route of penetration, the target rheological conditions, and the individual characteristics of the organism. Acute poisoning occurs as a result of a single exposure to large doses of harmful substances. Chronic poisoning develops as a result of long-term exposure to small concentrations of harmful substances (lead, mercury, manganese). Once harmful substances enter the body, they are unevenly distributed in it. The largest amount of lead accumulates in the bones, fluorine – in the teeth, manganese – in the liver. Such substances tend to form a so-called “depot” in the body and remain there for a long time.
According to the nature of the effect on the human body, harmful substances are divided into:
general toxic – substances that cause poisoning of the whole organism (carbon oxides, cyanide compounds, lead, mercury, benzene, arsenic and its compounds and others);
irritants – substances that cause irritation of the respiratory tract and mucous membranes (chlorine, ammonia, sulfur gas, hydrogen fluoride, nitrogen oxides, ozone, acetone, and others);
sensitizing – substances that act as allergens (formaldehyde, various solvents, lacquers based on nitroso- and nitro compounds, and others);
carcinogenic – substances that cause cancer (nickel and its compounds, amines, chromium oxides, asbestos and others);
mutagenic – substances that lead to changes in consequential information (lead, manganese, radioactive substances and others);
substances affecting the reproductive (childbearing) function (mercury, lead, manganese, styrene, radioactive substances and others).
Harmful substances that have entered the human body cause health problems only if their amount in the air exceeds the limit value for each substance. The maximum permissible concentration (MPC) of harmful substances in the working area is defined as such concentration, which during daily (except weekends) work for 8 hours or other duration (but not more than 40 hours per week) during the entire working experience cannot cause occupational diseases or health disorders determined by modern methods both in the process of work and in the distant lifetime of the present and future generations.
According to the value of the maximum permissible concentration in the air of the working area, harmful substances are divided into four classes of danger (GOST 12.1.007-76.):
1st – extremely dangerous substances, MPC less than 0.1 mg/m3 (lead, mercury, ozone).
2nd – highly dangerous substances, MPC 0.1…1.0 mg/m3 (sulfuric and hydrochloric acids, chlorine, phenol, caustic alkalis).
3rd – moderately dangerous substances, MPC 1.1…10.0 mg/m3 (vinyl acetate, toluene, xylene, methyl alcohol).
4th – substances of little danger, MPC more than 10.0 mg/m3 (ammonia, gasoline, acetone, kerosene).
It should be noted that in the list of MPCs, next to the normative value, there may be a letter that indicates the peculiarity of the action of this substance on the human body:
O – acutely directed action;
A – allergic action;
K – carcinogenic action;
F – fibrogenic action.
The table shows data on the impact of toxic pollution on human health.