This may be a bit of a difficult essay to read, since there is a lot of chemistry and biology stuff. If there are mistakes, I’m sorry, English isn’t my first language.

General characteristics.

The quality of the environment significantly affects the health of the population. Virtually all chemicals and physical radiation in varying degrees, have a harmful effect on human health, and here the level of their presence in the environment (concentration of a substance, dose of radiation received, etc.) is important. In case of adverse effects, mutagenic and carcinogenic effects are of paramount importance. It represents the danger of the effect of pollution on the child-bearing function and the health of children. A large number of chemicals are characterized by effects on the metabolic, immune and other systems that perform the protective functions of the body.

According to experimental and epidemiological studies, environmental factors, even with a low level of exposure, can cause significant health disorders. Contamination of the environment, despite relatively small concentrations of substances, due to the long duration of exposure (for almost the entire life of a person) can lead to serious health problems, especially for such unstable groups as children, the elderly, patients with chronic diseases, and pregnant women.

The most dangerous environmental pollutants.

Large volumes of environmental inputs of various chemicals, biological agents with a low level of control of industrial, agricultural, household and other pollutants do not allow to establish a sufficiently clear measure of the hazard to the health of technogenic pollutants contained in atmospheric air or soil, drinking water or food.

However, it is considered that in terms of the degree of danger to human health among chemical pollutants, primacy currently belongs to heavy metals, chlorinated hydrocarbons, nitrates, nitrites and nitro compounds, asbestos, and pesticides.

The most dangerous and toxic of heavy metals are cadmium, mercury and lead. A relationship has been established between the amount of cadmium, lead, arsenic found in water and soil, and the incidence rates of various forms of malignant neoplasms among the population in ecologically unfavorable areas.

Cadmium contamination of food products, as a rule, occurs due to contamination of soil and drinking water with sewage and other industrial waste, as well as with the use of phosphate fertilizers and pesticides. In the air of rural areas, the concentration of cadmium is 10 times higher than the levels of natural background, and in urban environments standards can be exceeded up to 100 times. Most people get cadmium from plant foods.

Mercury, like another biocide related to heavy metals, has two types of circulation in nature. The first is associated with the natural exchange of elemental (inorganic) mercury, the second, the so-called local, is due to the methylation processes of inorganic mercury released into the environment as a result of human activities. Mercury is used in the production of caustic soda, paper pulp, plastics synthesis, in the electrical industry. Mercury is widely used as a fungicide for dressing seed. Every year, up to 80 thousand tons of mercury in the form of vapors and aerosols are released into the atmosphere, from where it and its compounds migrate to the soil and water bodies.

In modern conditions, the main source of environmental pollution with lead compounds is the use of leaded gasoline. Naturally, the highest lead concentrations are found in the atmospheric air of cities and along major highways. In the future, when incorporated into the food chain, lead can enter the human body with products of both vegetable and animal origin. Lead can accumulate in the body, especially in bone tissue. There is evidence of the effect of lead on the growth of diseases of the cardiovascular system. Experimental data show that cancer in the presence of lead requires 5 times less carcinogenic hydrocarbons.

Drugs, mainly antibiotics, widely used in animal husbandry, are also a great danger to human health. The significance of their contamination of livestock products is associated with an increase in allergic reactions in humans to drugs.

6 different pesticides that have, in addition to the specific effect on agricultural pests, adverse  effects of various kinds (carcinogenic, embryotoxic, teratogenic, etc.). According to the National Academy of Sciences of the United States, toxicologists have relatively complete information on the health effects of only 10% of the pesticides currently used and 18% of the medicines used. At least 1/3 of pesticides and drugs pass no toxicity tests. For all chemicals used in the world, the problem is even more serious: 80% of them have not passed any tests.

It is well known that nitrates and nitrites are far from being harmless to the body. Nitrates used as mineral fertilizers are found in the highest concentrations in green vegetables, for example, in spinach, lettuce, sorrel, beets, carrots, and cabbage. High concentrations of nitrates in drinking water are especially dangerous, since their interaction with hemoglobin disrupts its functions as an oxygen carrier. There are phenomena of oxygen starvation with signs of shortness of breath, asphyxia. In severe cases, poisoning can be fatal. It has been experimentally proven that nitrates also have a mutagenic and embryotoxic effect.

Nitrites, which are salts of nitrous acid, have long been used as a preservative in the manufacture of sausages, ham, and canned meat. Another danger of nitrite being in food is that in the gastrointestinal tract under the influence of microflora from nitrites nitro compounds are formed that have carcinogenic properties.

Radionuclides that are persistent in ecological chains, enter the human body also mainly with food. Of the products of uranium splitting, strontium-90 and cesium-137 (having a half-life of about 30 years) are particularly dangerous: strontium, due to its similarity with calcium, very easily penetrates into the bone tissue of vertebrates, while cesium accumulates in muscular tissues, replacing potassium. They are able to accumulate in the body in quantities sufficient to cause damage to health, remaining in the infected body almost all its life and causing carcinogenic, mutagenic and other diseases.