lower parts of the atmosphere, which is harmful to living organisms. Unlike stratospheric ozone, its concentration in the troposphere is increasing. Excessive ozone amount in the troposphere is as harmful as its lack in the stratosphere. Tropospheric ozone can be of stratospheric origin or is a result of complex photochemical reactions of hydrocarbons, carbon monoxide and nitrogen oxides. *Stratospheric ozone* - ozone found in the stratosphere prevents the penetration of harmful short-wave UV-B radiation with a wavelength of 280–315 nm. As a consequence of photochemical reactions in the stratosphere, besides the formation and decay of ozone, not only is there a significant attenuation of the incident solar ultraviolet radiation, but also the transmission (absorption) of energy, and thus an increase in temperature in the respective atmosphere layers. As a result of human activity, substances are released into the atmosphere, the amount of which exceeds the normal value of their occurrence in the atmosphere several times. This reduces the amount of ozone in the ozonosphere and disrupts the natural structure of the atmosphere, which permits much more UV-radiation at wavelengths that adversely affect living organisms. The stratospheric ozone layer is increasingly disrupted by the action of chlorofluorocarbons (CFCs or Freons). Freons have been developed in the 1930s, have a very wide use, are non-flammable, non-toxic, odorless, cheap and lighter than air. As a result of UV-radiation, the atoms of the halo elements (chlorine, bromine) are released, converting ozone to oxygen molecules that do not absorb UV. The decrease of ozone in the stratosphere allows ultraviolet rays to get to the Earth. Negative effects on living organisms include skin cancer, eye diseases, weakening of the immune system and others [3, 10, 13–15]. Ultraviolet rays do not only damage living organisms, but also contribute to the deterioration of plastics, wood, paper and cotton. The amount of both tropospheric and stratospheric ozone depends on the balance between the processes in which ozone is produced and the processes in which ozone is disposed of in the atmosphere. In the last quarter of the 20th century, it was found that stratospheric ozone was disappearing, while tropospheric ozone was increasing. Even though stratospheric ozone is naturally produced and destroyed by a constant, balanced rate, people are gradually disrupting this balance by using ozone-consuming substances. *Acid rain* is the result of strong air pollution, where dirt absorbed by air humidity gets back to the ground through precipitation. Rainwater with a pH value of 5.0–5.6 is slightly acidic because carbon dioxide is found in the air and absorbed by the air humidity. Acid rain is considered to be rainwater with a pH of 2.0–5.0. *The occurrence of acid rain* is mainly due to coal and oil-fired power plants, metallurgical plants, the chemical industry and transport. Sulfur and nitrogen oxides emitted by these sources combine with atmospheric moisture to form sulfuric and nitric acids. These rains have a negative impact on flora and fauna. They kill fish in lakes in bulk. Acid rain threatens plants, forests (healthy coniferous trees lose their needles after 6–8 years, sick ones after 2–3 years, only the newest needles remain on damaged coniferous trees, plant roots absorb toxins more easily in acidic environment) worms, insects and other animals that process plant remnants in healthy soil (thus enriching the soil with substances that are vital to plant life). However, if the soil is acidified by acid rain, the animals cannot live in it. Dead plant residues remain lying on the ground and no animal nutrients are formed. The food chain is disrupted. Some of the nutrients such as calcium, manganese, sodium, potassium is diluted from the soil due to the effects of acidic components of the rain; groundwater and surface water are (acidified water has a negative effect on aquatic animals and aquatic plants). Under these conditions, phytoplankton gradually disappears and due to its reduction, the light gets deeper into the water, so the water of the affected lakes is almost unnaturally clear and clean. Today, for example, only in Sweden out of 100,000 lakes, (about 20,000 are dead, lifeless), acid rains are damaging buildings, artistic and cultural

**37**

cyanide [3, 6, 10, 14].

**3. Hydrosphere**

*Heavy Metals and the Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86876*

landmarks. Not all sites respond to acid rain in the same way - it depends on the soil and water chemical composition. There are some sites with alkaline soil that can tolerate large doses of acid rain without significantly changing the overall pH of the environment. Acid aerosols also have a harmful effect on humans by entering the respiratory tract, irritating the mucosa and thus facilitating the entry of infections into the lungs. *The greenhouse effect* is the denotation of a phenomenon consisting of warming the lower layers of the atmosphere due to the fact that the atmosphere permits the passage of short-wave solar radiation to the Earth's surface during the day and absorbs Earth's long-wave radiation at night and thus becomes warmer. Larger wavelength heat radiation, which is emitted back from the planet's surface, is absorbed by the Earth effectively, its immediate release into space being prevented this way. The anthropogenic greenhouse effect is caused by the burning of fossil fuels, the excavation of forests, the global changes in the countryside, and contributes to global warming. Among the greenhouse gases currently having the greatest climate impact belongs carbon dioxide. It occurred naturally in the atmosphere. From 1850 to the present, its concentration increased by 27%. It is released in the burning of fossil fuels and its amount is growing due to massive deforestation too. Part of it is absorbed by the oceans and much of it by forested areas. Another significant greenhouse gas is *methane*. In the atmosphere it occurs naturally, as does carbon dioxide. It is produced by anaerobic bacteria in the digestive tract of ruminants and by the decomposition of organic matter. It is released from subsurface landfills and is also released into the atmosphere by escaping from gas pipelines. *Nitrous oxide* is a naturally occurring greenhouse gas. Its presence is increased by using nitrogen fertilizers and burning fossil fuels. *Freons* have anthropogenic origin. They are found in refrigerant gases and are part of the propellants. They disrupt the ozone layer. We are currently adding nearly 10 billion tons of carbon to the atmosphere annually. The biosphere is not capable of returning such an amount back to underground reservoirs as fossils, nor is the world ocean able to drain such an amount of carbon because of physical and chemical limitations. This is the main reason that the concentration of CO2 but also of CH4 in the atmosphere grows in parallel with the consumption of fossil carbon by various anthropogenic activities. *Nitrogen* is an indifferent part of the air in respect to health. Oxygen is the most important component of air, resulting from its role in respiratory physiology. The human organism is highly resistant to fluctuations in the amount of oxygen. Ozone is of little use for low concentration under natural conditions. However, it is harmful and even dangerous at high concentrations. *Carbon monoxide* is an unnatural admixture in the air. Its hygienic importance lies above all in the danger of poisoning. It is particularly dangerous because humans cannot smell it. *Sulfur dioxide* is produced by the combustion of sulfur and acts irritatingly and even as a strong poison. *Ammonia* occurs only in trace amounts in the atmosphere. It is harmful at a concentration of 0.5%, which it practically does not reach. Odorous substances are produced in an enclosed atmosphere by anthropogenic and animal activity. Further impurities in the air are e.g. mercury, and gasoline vapor, hydrogen

Hydrosphere (from Greek hydro - water) is a denotation that encompasses all water, whether on the surface of the Earth or bellow it and in any form... Water is the most widespread, under the surface of the Earth. Water occurs in different states and creates a discontinuous water layer of the Earth (hydrosphere). These include the waters of the oceans, seas, surface waters, and, in a broader sense, soil

#### *Heavy Metals and the Environment DOI: http://dx.doi.org/10.5772/intechopen.86876*

*Environmental Factors Affecting Human Health*

lower parts of the atmosphere, which is harmful to living organisms. Unlike stratospheric ozone, its concentration in the troposphere is increasing. Excessive ozone amount in the troposphere is as harmful as its lack in the stratosphere. Tropospheric ozone can be of stratospheric origin or is a result of complex photochemical reactions of hydrocarbons, carbon monoxide and nitrogen oxides. *Stratospheric ozone* - ozone found in the stratosphere prevents the penetration of harmful short-wave UV-B radiation with a wavelength of 280–315 nm. As a consequence of photochemical reactions in the stratosphere, besides the formation and decay of ozone, not only is there a significant attenuation of the incident solar ultraviolet radiation, but also the transmission (absorption) of energy, and thus an increase in temperature in the respective atmosphere layers. As a result of human activity, substances are released into the atmosphere, the amount of which exceeds the normal value of their occurrence in the atmosphere several times. This reduces the amount of ozone in the ozonosphere and disrupts the natural structure of the atmosphere, which permits much more UV-radiation at wavelengths that adversely affect living organisms. The stratospheric ozone layer is increasingly disrupted by the action of chlorofluorocarbons (CFCs or Freons). Freons have been developed in the 1930s, have a very wide use, are non-flammable, non-toxic, odorless, cheap and lighter than air. As a result of UV-radiation, the atoms of the halo elements (chlorine, bromine) are released, converting ozone to oxygen molecules that do not absorb UV. The decrease of ozone in the stratosphere allows ultraviolet rays to get to the Earth. Negative effects on living organisms include skin cancer, eye diseases, weakening of the immune system and others [3, 10, 13–15]. Ultraviolet rays do not only damage living organisms, but also contribute to the deterioration of plastics, wood, paper and cotton. The amount of both tropospheric and stratospheric ozone depends on the balance between the processes in which ozone is produced and the processes in which ozone is disposed of in the atmosphere. In the last quarter of the 20th century, it was found that stratospheric ozone was disappearing, while tropospheric ozone was increasing. Even though stratospheric ozone is naturally produced and destroyed by a constant, balanced rate, people are gradually disrupting this balance by using ozone-consuming substances. *Acid rain* is the result of strong air pollution, where dirt absorbed by air humidity gets back to the ground through precipitation. Rainwater with a pH value of 5.0–5.6 is slightly acidic because carbon dioxide is found in the air and absorbed by the air humidity. Acid rain is considered to be rainwater with a pH of 2.0–5.0. *The occurrence of acid rain* is mainly due to coal and oil-fired power plants, metallurgical plants, the chemical industry and transport. Sulfur and nitrogen oxides emitted by these sources combine with atmospheric moisture to form sulfuric and nitric acids. These rains have a negative impact on flora and fauna. They kill fish in lakes in bulk. Acid rain threatens plants, forests (healthy coniferous trees lose their needles after 6–8 years, sick ones after 2–3 years, only the newest needles remain on damaged coniferous trees, plant roots absorb toxins more easily in acidic environment) worms, insects and other animals that process plant remnants in healthy soil (thus enriching the soil with substances that are vital to plant life). However, if the soil is acidified by acid rain, the animals cannot live in it. Dead plant residues remain lying on the ground and no animal nutrients are formed. The food chain is disrupted. Some of the nutrients such as calcium, manganese, sodium, potassium is diluted from the soil due to the effects of acidic components of the rain; groundwater and surface water are (acidified water has a negative effect on aquatic animals and aquatic plants). Under these conditions, phytoplankton gradually disappears and due to its reduction, the light gets deeper into the water, so the water of the affected lakes is almost unnaturally clear and clean. Today, for example, only in Sweden out of 100,000 lakes, (about 20,000 are dead, lifeless), acid rains are damaging buildings, artistic and cultural

**36**

landmarks. Not all sites respond to acid rain in the same way - it depends on the soil and water chemical composition. There are some sites with alkaline soil that can tolerate large doses of acid rain without significantly changing the overall pH of the environment. Acid aerosols also have a harmful effect on humans by entering the respiratory tract, irritating the mucosa and thus facilitating the entry of infections into the lungs. *The greenhouse effect* is the denotation of a phenomenon consisting of warming the lower layers of the atmosphere due to the fact that the atmosphere permits the passage of short-wave solar radiation to the Earth's surface during the day and absorbs Earth's long-wave radiation at night and thus becomes warmer. Larger wavelength heat radiation, which is emitted back from the planet's surface, is absorbed by the Earth effectively, its immediate release into space being prevented this way. The anthropogenic greenhouse effect is caused by the burning of fossil fuels, the excavation of forests, the global changes in the countryside, and contributes to global warming. Among the greenhouse gases currently having the greatest climate impact belongs carbon dioxide. It occurred naturally in the atmosphere. From 1850 to the present, its concentration increased by 27%. It is released in the burning of fossil fuels and its amount is growing due to massive deforestation too. Part of it is absorbed by the oceans and much of it by forested areas. Another significant greenhouse gas is *methane*. In the atmosphere it occurs naturally, as does carbon dioxide. It is produced by anaerobic bacteria in the digestive tract of ruminants and by the decomposition of organic matter. It is released from subsurface landfills and is also released into the atmosphere by escaping from gas pipelines. *Nitrous oxide* is a naturally occurring greenhouse gas. Its presence is increased by using nitrogen fertilizers and burning fossil fuels. *Freons* have anthropogenic origin. They are found in refrigerant gases and are part of the propellants. They disrupt the ozone layer. We are currently adding nearly 10 billion tons of carbon to the atmosphere annually. The biosphere is not capable of returning such an amount back to underground reservoirs as fossils, nor is the world ocean able to drain such an amount of carbon because of physical and chemical limitations. This is the main reason that the concentration of CO2 but also of CH4 in the atmosphere grows in parallel with the consumption of fossil carbon by various anthropogenic activities. *Nitrogen* is an indifferent part of the air in respect to health. Oxygen is the most important component of air, resulting from its role in respiratory physiology. The human organism is highly resistant to fluctuations in the amount of oxygen. Ozone is of little use for low concentration under natural conditions. However, it is harmful and even dangerous at high concentrations. *Carbon monoxide* is an unnatural admixture in the air. Its hygienic importance lies above all in the danger of poisoning. It is particularly dangerous because humans cannot smell it. *Sulfur dioxide* is produced by the combustion of sulfur and acts irritatingly and even as a strong poison. *Ammonia* occurs only in trace amounts in the atmosphere. It is harmful at a concentration of 0.5%, which it practically does not reach. Odorous substances are produced in an enclosed atmosphere by anthropogenic and animal activity. Further impurities in the air are e.g. mercury, and gasoline vapor, hydrogen cyanide [3, 6, 10, 14].

## **3. Hydrosphere**

Hydrosphere (from Greek hydro - water) is a denotation that encompasses all water, whether on the surface of the Earth or bellow it and in any form... Water is the most widespread, under the surface of the Earth. Water occurs in different states and creates a discontinuous water layer of the Earth (hydrosphere). These include the waters of the oceans, seas, surface waters, and, in a broader sense, soil and groundwater, water bound in glaciers and snow, atmospheric water, and water in living organisms. on the Earth and for the animals it is directly the environment for their living. It is the main means of transporting nutrients, receiving and excreting them. Water on Earth occupies about 2/3 of its total surface area (drinking water represents about 1% of the total water; 97% saltwater contained in seas and oceans; 2% water bound in glaciers). The total water volume is about 1385 billion km3 . The origin and development of the hydrosphere is closely linked to the evolution of the rest of the Earth. Between the lithosphere, the atmosphere and the hydrosphere, there is a constant exchange of water causing changes in the chemical and isotopic composition of water. Continuous water circulation is caused by solar energy and gravity. Large (global) water cycle takes place between the ocean and the mainland, and a small water cycle arises over the oceans. In the various phases of the cycle, complex water conversion takes place [3, 6, 10]. *Meaning, function, properties and distribution of water:* The health of the population as a universal value and primary human rights represent the fundamental economic resource not only for the individual but also for the whole of society. In recent years, information has been gathering to warn of the catastrophic effects of unscrupulous industrial devastation of natural resources, water resources, and interventions in the ecological balance of flora and fauna. Water is an indispensable component of the human environment, as well as all plant and animal systems, and constitutes the basic condition of life on Earth. It is an important prerequisite for the existence of every living matter on Earth. *The importance of water for man and the environment* was accurately defined in the 12 points of the European Water Charter, proclaimed by the European Council on 6 May 1948 in Strasbourg: The Water Charter underlines the necessity to maintain sufficient water for future generations and the fact that water does not recognize state borders. Therefore, the growing water problems require international cooperation. According to data from the United Nations, polluted water kills more people than war. Up to 2 billion tons of polluted waste is discharged daily into the water worldwide. About 2 million people die of dehydration in developing countries every year on our planet, with about one in five people having no access to drinking water.  According to the UN, about 783 million Earth inhabitants does not have access to drinking water and about 2.5 billion people do not know sanitation systems, while the quality of water resources is worse. The human body contains more than 60% water (65–75%), which is about 2/3 of the body weight. This ratio is even higher in children and newborns. Water plays an irreplaceable and irredeemable role in the life and function of the body as it participates in the digestion and metabolism, body temperature regulation, excretion of body waste, transport of oxygen and nutrients to tissues and cells. *The amount of drinking water received depends on several factors*: age, activity, environment in which a person lives, condition of the body, nutrition (composition of diet). Lack of water leads to serious damage to the human body after only a few days. In the case of excessive loss of water from the body, we feel drowsiness, weakness, confusion. Dry mucous membranes, constipation, headache, fatigue, somnolence, impaired movement coordination, pulse acceleration, drop in blood pressure and decreased performance are also *manifestations of water deficiency*. *In case of excessive fluid loss*, we are talking about dehydration. Loss of fluid above 6% can lead to collapse or death. *In the case of insufficient water supply*, harmful substances accumulate in the body, which puts the excretory organs under stress. The thicker the blood, the more difficult it becomes for the kidneys to deal with the waste. Water in tissues, blood, and lymph are thickened, weakening the immune system, failing to transmit nerve impulses, slowing cell renewal. Water is also important for thermoregulatory processes and protects the body from

**39**

*Heavy Metals and the Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86876*

overheating. *Water functions*: *biological function* – it is the essential condition for the life of organisms from microorganisms to higher animals to humans, it provides nutrition for humanity, for some animal species water is their living environment, water participates in photosynthesis, it is part of components in the cell as well as regulator of thermal properties*, health preserving function* - the quality of life, hygiene, health, healing properties of mineralized and otherwise enriched waters depend on it; *economic function* – it is applied in the agricultural industry, *estheticcultural functions* - spas, water bodies fulfill the appropriate function, *political function* - watercourses form borders between states. *Water properties:* The physical, chemical and biological properties of water result from its structure and chemical composition. From a physical and chemical point of view, water is a very complicated compound characterized by a number of special chemical and physical properties resulting from the electron structure of its molecules. Water properties are divided into chemical, physical, microbiological and sensory. *The chemical properties of water* - water contains a wide range of chemicals, some of which are only minuscule and desirable (carbonates); others should only be present in limited quantities because they could change the color and haze properties (turbidity) of water (iron, chlorine) and there is also a group of substances undesirable in water that indicates water pollution with nitrogenous substances ((ammonia, nitrites, nitrates, phosphates, chlorides) of organic origin, etc.) [6, 14]. The chemical properties of water are determined by the content of substances dissolved in water. The main inorganic constituents of natural waters are calcium, magnesium and sodium, which are mostly present as cations such as bicarbonates, sulfates and chlorides. In natural waters, potassium, iron, manganese and small amounts of other metals are represented in small concentrations, by which the water is enriched in contact with the soil, with various minerals and rocks. From a chemical point of view, we divide the substances found in waters into inorganic and organic. From a physical point of view, these substances can be present as ionically dissolved (electrolytes), non-ionically dissolved (non-electrolytes) or as undissolved (nonmiscible, miscible and buoyant or floating). *Physical properties of water*: ability to accumulate more heat; large water bodies such as lakes, seas and oceans are involved

in the regulation of temperature on the Earth, electrical conductivity, which depends on ion concentration, their mobility and temperature, while the dissolved salts and gases increase the water conductivity, the water density increases from temperature of 0 to 3.98°C, at higher temperature it decreases continuously, surface tension - is the cause of capillary phenomena (capillarity of water in the soil and rocks, wetting ability, foam formation, etc.), viscosity, which together with density significantly affects hydraulic water behavior - for example, the speed of sand filtration of water depends on its value, sedimentation rate that decreases with temperature rise. Other physical properties of water include light absorption, water radioactivity, and state changes. *Biological properties of water:* The microbial recovery of natural waters consists of autochthonous (indigenous) species, for which water is the primary and natural habitat, where they participate in the circulation of substances in water and are thus reflecting natural water pollution without anthropogenic influence. Microorganisms that get into the aquatic environment by flushing from the soil, or through civilization wastes, whether communal, industrial, or agricultural, and survive for some time in this environment, represent an allochthonous (non-original) recovery, indicating not only external pollution by organic substances, but also the possibility of pathogenic germs. There are many microbial species *in natural waters.* Microbiological analyzes are carried out in a targeted manner, and indicator groups or individual species of microorganisms as indicators of water quality are selected purposefully according to ecological or hygienic criteria. Ecological classification of organisms expresses the behavior and

#### *Heavy Metals and the Environment DOI: http://dx.doi.org/10.5772/intechopen.86876*

*Environmental Factors Affecting Human Health*

billion km3

and groundwater, water bound in glaciers and snow, atmospheric water, and water in living organisms. on the Earth and for the animals it is directly the environment for their living. It is the main means of transporting nutrients, receiving and excreting them. Water on Earth occupies about 2/3 of its total surface area (drinking water represents about 1% of the total water; 97% saltwater contained in seas and oceans; 2% water bound in glaciers). The total water volume is about 1385

evolution of the rest of the Earth. Between the lithosphere, the atmosphere and the hydrosphere, there is a constant exchange of water causing changes in the chemical and isotopic composition of water. Continuous water circulation is caused by solar energy and gravity. Large (global) water cycle takes place between the ocean and the mainland, and a small water cycle arises over the oceans. In the various phases of the cycle, complex water conversion takes place [3, 6, 10]. *Meaning, function, properties and distribution of water:* The health of the population as a universal value and primary human rights represent the fundamental economic resource not only for the individual but also for the whole of society. In recent years, information has been gathering to warn of the catastrophic effects of unscrupulous industrial devastation of natural resources, water resources, and interventions in the ecological balance of flora and fauna. Water is an indispensable component of the human environment, as well as all plant and animal systems, and constitutes the basic condition of life on Earth. It is an important prerequisite for the existence of every living matter on Earth. *The importance of water for man and the environment* was accurately defined in the 12 points of the European Water Charter, proclaimed by the European Council on 6 May 1948 in Strasbourg: The Water Charter underlines the necessity to maintain sufficient water for future generations and the fact that water does not recognize state borders. Therefore, the growing water problems require international cooperation. According to data from the United Nations, polluted water kills more people than war. Up to 2 billion tons of polluted waste is discharged daily into the water worldwide. About 2 million people die of dehydration in developing countries every year on our planet, with about one in five people having no access to drinking water.  According to the UN, about 783 million Earth inhabitants does not have access to drinking water and about 2.5 billion people do not know sanitation systems, while the quality of water resources is worse. The human body contains more than 60% water (65–75%), which is about 2/3 of the body weight. This ratio is even higher in children and newborns. Water plays an irreplaceable and irredeemable role in the life and function of the body as it participates in the digestion and metabolism, body temperature regulation, excretion of body waste, transport of oxygen and nutrients to tissues and cells. *The amount of drinking water received depends on several factors*: age, activity, environment in which a person lives, condition of the body, nutrition (composition of diet). Lack of water leads to serious damage to the human body after only a few days. In the case of excessive loss of water from the body, we feel drowsiness, weakness, confusion. Dry mucous membranes, constipation, headache, fatigue, somnolence, impaired movement coordination, pulse acceleration, drop in blood pressure and decreased performance are also *manifestations of water deficiency*. *In case of excessive fluid loss*, we are talking about dehydration. Loss of fluid above 6% can lead to collapse or death. *In the case of insufficient water supply*, harmful substances accumulate in the body, which puts the excretory organs under stress. The thicker the blood, the more difficult it becomes for the kidneys to deal with the waste. Water in tissues, blood, and lymph are thickened, weakening the immune system, failing to transmit nerve impulses, slowing cell renewal. Water is

also important for thermoregulatory processes and protects the body from

. The origin and development of the hydrosphere is closely linked to the

**38**

overheating. *Water functions*: *biological function* – it is the essential condition for the life of organisms from microorganisms to higher animals to humans, it provides nutrition for humanity, for some animal species water is their living environment, water participates in photosynthesis, it is part of components in the cell as well as regulator of thermal properties*, health preserving function* - the quality of life, hygiene, health, healing properties of mineralized and otherwise enriched waters depend on it; *economic function* – it is applied in the agricultural industry, *estheticcultural functions* - spas, water bodies fulfill the appropriate function, *political function* - watercourses form borders between states. *Water properties:* The physical, chemical and biological properties of water result from its structure and chemical composition. From a physical and chemical point of view, water is a very complicated compound characterized by a number of special chemical and physical properties resulting from the electron structure of its molecules. Water properties are divided into chemical, physical, microbiological and sensory. *The chemical properties of water* - water contains a wide range of chemicals, some of which are only minuscule and desirable (carbonates); others should only be present in limited quantities because they could change the color and haze properties (turbidity) of water (iron, chlorine) and there is also a group of substances undesirable in water that indicates water pollution with nitrogenous substances ((ammonia, nitrites, nitrates, phosphates, chlorides) of organic origin, etc.) [6, 14]. The chemical properties of water are determined by the content of substances dissolved in water. The main inorganic constituents of natural waters are calcium, magnesium and sodium, which are mostly present as cations such as bicarbonates, sulfates and chlorides. In natural waters, potassium, iron, manganese and small amounts of other metals are represented in small concentrations, by which the water is enriched in contact with the soil, with various minerals and rocks. From a chemical point of view, we divide the substances found in waters into inorganic and organic. From a physical point of view, these substances can be present as ionically dissolved (electrolytes), non-ionically dissolved (non-electrolytes) or as undissolved (nonmiscible, miscible and buoyant or floating). *Physical properties of water*: ability to accumulate more heat; large water bodies such as lakes, seas and oceans are involved in the regulation of temperature on the Earth, electrical conductivity, which depends on ion concentration, their mobility and temperature, while the dissolved salts and gases increase the water conductivity, the water density increases from temperature of 0 to 3.98°C, at higher temperature it decreases continuously, surface tension - is the cause of capillary phenomena (capillarity of water in the soil and rocks, wetting ability, foam formation, etc.), viscosity, which together with density significantly affects hydraulic water behavior - for example, the speed of sand filtration of water depends on its value, sedimentation rate that decreases with temperature rise. Other physical properties of water include light absorption, water radioactivity, and state changes. *Biological properties of water:* The microbial recovery of natural waters consists of autochthonous (indigenous) species, for which water is the primary and natural habitat, where they participate in the circulation of substances in water and are thus reflecting natural water pollution without anthropogenic influence. Microorganisms that get into the aquatic environment by flushing from the soil, or through civilization wastes, whether communal, industrial, or agricultural, and survive for some time in this environment, represent an allochthonous (non-original) recovery, indicating not only external pollution by organic substances, but also the possibility of pathogenic germs. There are many microbial species *in natural waters.* Microbiological analyzes are carried out in a targeted manner, and indicator groups or individual species of microorganisms as indicators of water quality are selected purposefully according to ecological or hygienic criteria. Ecological classification of organisms expresses the behavior and

application of organisms in certain physiological conditions and their ability to survive and adapt in new and more difficult conditions. Systematic division of organisms is done either from the perspective of their development or family relationships. This includes microorganisms, plants and animals. Ecological division relates to the participation of organisms in the circulation of substances in the aquatic environment and recognizes producers, consumers and destroyers. Producers are organisms able to assimilate inorganic nutrients and synthesize organic substances such as carbohydrates, proteins and fats from them. These include autotrophic bacteria, higher plants, algae, cyanobacteria. The source of energy is either light radiation, e.g. for algae, photosynthesis in plants or some oxidation–reduction reactions. In the case of photosynthesis, in addition to organic substances, producers also generate oxygen which can enrich water and air. Producers are the bases of aerobic life on the Earth and their photosynthesis is significantly utilized in self-purification of water. Consumers feed on finished organic substances that are processed by endoenzymes inside their bodies. Consumers include animals from protozoa to arthropods. Together with destructants they represent an organotrophic (heterotrophic) diet. Consumers release the waste substances of their metabolism into the water, especially carbon dioxide. Decomposers feed on finished organic substances. Since they do not have any food intake organs, they decompose high molecular weight substances outside of their body by exoenzymes into simpler molecules that can penetrate the cell wall into a destructive cell [3, 10, 13–15].

#### **3.1 Division of water by origin, pollution, causes**

*Precipitation (atmospheric)* water forms - occur in the air in the form of clouds, water vapor, precipitation and fog. This type of water is considered the cleanest, but it is contaminated by passing through polluted air layers. The greatest influence on the chemical composition of atmospheric waters has a layer of atmosphere that extends from the Earth's surface to a height of 1000–1500 m. *Surface water* - represents water that is permanently or temporarily on the surface of the Earth and is divided into: *flowing* (natural - streams, rivers, artificial - canals, conduits), stagnant (natural - seas, oceans, lakes, artificial - ponds, water reservoirs). Pollution of surface waters – the so-called "Eutrophication" is a set of natural and man-made processes leading to an increase in inorganic nutrients in water, especially nitrogen and phosphorus compounds, followed by increased growth of cyanobacteria, algae and higher plant forms, resulting in worsened ecological stability and reduced water quality. Phosphorus in surface waters comes from sewage and phosphate fertilizers used in agriculture. Nitrogen and phosphorus compounds mainly come from waste related to animal husbandry, industrial production and from sewage "water". An important source of surface water pollution is the excessive application of NPK fertilizers to the soil. It occurs mainly in stagnant, slow-flowing waters, but eutrophication can also occur in watercourses under favorable conditions (strong nutrient supply, increased water temperature and slowed flow of water). *Groundwater* is created by infiltration of rainwater and surface water into the Earth's crust. Groundwater is of fundamental importance in the hydrological cycle in supplying the population with drinking water. Groundwater pollution by nitrates is an issue that has been given increased attention in the area of groundwater protection against pollution The increased level of nitrates in groundwater is contributed to by anthropogenic activity, e.g. the application of industrial and artificial fertilizers to agricultural land, discharge of waste water from settlements and industrial buildings. Increased concentrations of nitrates in groundwater have a negative impact on both the environment and human health, since groundwater is preferably used as a

**41**

**4. Pedospere**

*Heavy Metals and the Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86876*

source of drinking water. In particular, the prevention of groundwater pollution by nitrogen compounds is provided by integrated territorial protection of areas with potentially endangered groundwater bodies. Thus, *contamination of water resources* can be physical (occurrence of insoluble sludge and radioactive substances),

chemical (water-soluble impurities), biological (germs present). Thus the pollution itself occurs by the already mentioned increased use of fertilizers and pesticide preparations, leakage of silage juices, leakage of liquid parts of fertilizers from farms, leakage of lubricating oils, fuels and so on. *Pollutants (substances contributing to pollution)* - substances directly toxic (heavy metals, cyanides, pesticides), water pollutants (dyes, oil and relates substances), substances affecting the amount of oxygen in the water (high levels of degradable substances, at the decomposition of which large quantities of O2 in water are consumed), inert inorganic substances dissolved, undissolved, non-toxic [3, 10, 13, 14]. *Causes of water source pollution-*Man affects the quantity and quality of water resources directly through uncontrolled discharge of wastewater into watercourses or through sewerage networks. Waste water producers in the Slovak Republic are mainly industry and municipal sphere - sewerage systems of towns and villages. Inadequate purification results in high concentrations of pollutants and substances supporting the development of algae and plankton - phosphorus (P), nitrogen (N) - into the surface waters, resulting in an overall deterioration of water quality in streams and in stagnant waters (eutrophication). In the area of groundwater quality in the Slovak Republic, the issue of adverse oxidation–reduction conditions is at the forefront, which is often indicated by increased concentrations of iron (Fe), manganese (Mn), and NH4. Almost all metals are naturally found in surface and groundwater. Many of them are indispensable to life but may be harmful at higher concentrations. Metals with toxic properties, which are among the most important inorganic contaminants of waters and soils, become hygienically serious. The presence of cadmium (Cd), mercury (Hg) and chromium (Cr) is currently one of the most recent risks. Toxic metals have a negative impact not only on the surrounding environment, but especially on human and animal health. They also have an impact on flora and fauna [3, 8, 15–17].

Soil is a natural formation that arises directly on the Earth's surface as a product of the interaction of climatic conditions, organisms, humans, relief and parent rocks Act 34/2014 Coll., amending and supplementing Act 220/2004 Coll., On the (Protection and Use of Agricultural Land). Soil is a complex system of abiotic and biotic components and is the result of soil-forming factors. It is created on the interface of the atmosphere, the lithosphere, the hydrosphere and the biosphere, which to a great extent influences its composition. In the soil-forming processes, abiotic and biotic environmental factors are applied together, and the result of their action is the abiotic-biotic component of the environment - soil. *The main abiotic factors* involved in soil formation include: parent (soil-forming) rock, relief, water and climatic conditions. The chemical composition of the soil depends primarily on the parent rock from which the soil originated, from the processes running in the soil and from the activity of man. Soil contains most oxygen (about 50%) and silicon (about 25%), other elements are mainly aluminum (clay), iron, calcium (limestone, gypsum), sodium, potassium, magnesium, hydrogen, titanium, in lesser amounts carbon, chlorine, phosphorus, sulfur and manganese. *Biotic agents* include soil edaphone. These factors are collectively called soil-forming factors. Edaphone is a living component of soil. It is a set of soil microorganisms, fungi, plants and animals. Soil organisms (geo bionti, edafonti) live in slots washed

#### *Heavy Metals and the Environment DOI: http://dx.doi.org/10.5772/intechopen.86876*

*Environmental Factors Affecting Human Health*

destructive cell [3, 10, 13–15].

**3.1 Division of water by origin, pollution, causes**

application of organisms in certain physiological conditions and their ability to survive and adapt in new and more difficult conditions. Systematic division of organisms is done either from the perspective of their development or family relationships. This includes microorganisms, plants and animals. Ecological division relates to the participation of organisms in the circulation of substances in the

aquatic environment and recognizes producers, consumers and destroyers. Producers are organisms able to assimilate inorganic nutrients and synthesize organic substances such as carbohydrates, proteins and fats from them. These include autotrophic bacteria, higher plants, algae, cyanobacteria. The source of energy is either light radiation, e.g. for algae, photosynthesis in plants or some oxidation–reduction reactions. In the case of photosynthesis, in addition to organic

substances, producers also generate oxygen which can enrich water and air. Producers are the bases of aerobic life on the Earth and their photosynthesis is significantly utilized in self-purification of water. Consumers feed on finished organic substances that are processed by endoenzymes inside their bodies. Consumers include animals from protozoa to arthropods. Together with destructants they represent an organotrophic (heterotrophic) diet. Consumers release the waste substances of their metabolism into the water, especially carbon dioxide. Decomposers feed on finished organic substances. Since they do not have any food intake organs, they decompose high molecular weight substances outside of their body by exoenzymes into simpler molecules that can penetrate the cell wall into a

*Precipitation (atmospheric)* water forms - occur in the air in the form of clouds, water vapor, precipitation and fog. This type of water is considered the cleanest, but it is contaminated by passing through polluted air layers. The greatest influence on the chemical composition of atmospheric waters has a layer of atmosphere that extends from the Earth's surface to a height of 1000–1500 m. *Surface water* - represents water that is permanently or temporarily on the surface of the Earth and is divided into: *flowing* (natural - streams, rivers, artificial - canals, conduits), stagnant (natural - seas, oceans, lakes, artificial - ponds, water reservoirs). Pollution of surface waters – the so-called "Eutrophication" is a set of natural and man-made processes leading to an increase in inorganic nutrients in water, especially nitrogen and phosphorus compounds, followed by increased growth of cyanobacteria, algae and higher plant forms, resulting in worsened ecological stability and reduced water quality. Phosphorus in surface waters comes from sewage and phosphate fertilizers used in agriculture. Nitrogen and phosphorus compounds mainly come from waste related to animal husbandry, industrial production and from sewage "water". An important source of surface water pollution is the excessive application of NPK fertilizers to the soil. It occurs mainly in stagnant, slow-flowing waters, but eutrophication can also occur in watercourses under favorable conditions (strong nutrient supply, increased water temperature and slowed flow of water). *Groundwater* is created by infiltration of rainwater and surface water into the Earth's crust. Groundwater is of fundamental importance in the hydrological cycle in supplying the population with drinking water. Groundwater pollution by nitrates is an issue that has been given increased attention in the area of groundwater protection against pollution The increased level of nitrates in groundwater is contributed to by anthropogenic activity, e.g. the application of industrial and artificial fertilizers to agricultural land, discharge of waste water from settlements and industrial buildings. Increased concentrations of nitrates in groundwater have a negative impact on both the environment and human health, since groundwater is preferably used as a

**40**

source of drinking water. In particular, the prevention of groundwater pollution by nitrogen compounds is provided by integrated territorial protection of areas with potentially endangered groundwater bodies. Thus, *contamination of water resources* can be physical (occurrence of insoluble sludge and radioactive substances), chemical (water-soluble impurities), biological (germs present). Thus the pollution itself occurs by the already mentioned increased use of fertilizers and pesticide preparations, leakage of silage juices, leakage of liquid parts of fertilizers from farms, leakage of lubricating oils, fuels and so on. *Pollutants (substances contributing to pollution)* - substances directly toxic (heavy metals, cyanides, pesticides), water pollutants (dyes, oil and relates substances), substances affecting the amount of oxygen in the water (high levels of degradable substances, at the decomposition of which large quantities of O2 in water are consumed), inert inorganic substances dissolved, undissolved, non-toxic [3, 10, 13, 14]. *Causes of water source pollution-*Man affects the quantity and quality of water resources directly through uncontrolled discharge of wastewater into watercourses or through sewerage networks. Waste water producers in the Slovak Republic are mainly industry and municipal sphere - sewerage systems of towns and villages. Inadequate purification results in high concentrations of pollutants and substances supporting the development of algae and plankton - phosphorus (P), nitrogen (N) - into the surface waters, resulting in an overall deterioration of water quality in streams and in stagnant waters (eutrophication). In the area of groundwater quality in the Slovak Republic, the issue of adverse oxidation–reduction conditions is at the forefront, which is often indicated by increased concentrations of iron (Fe), manganese (Mn), and NH4. Almost all metals are naturally found in surface and groundwater. Many of them are indispensable to life but may be harmful at higher concentrations. Metals with toxic properties, which are among the most important inorganic contaminants of waters and soils, become hygienically serious. The presence of cadmium (Cd), mercury (Hg) and chromium (Cr) is currently one of the most recent risks. Toxic metals have a negative impact not only on the surrounding environment, but especially on human and animal health. They also have an impact on flora and fauna [3, 8, 15–17].

## **4. Pedospere**

Soil is a natural formation that arises directly on the Earth's surface as a product of the interaction of climatic conditions, organisms, humans, relief and parent rocks Act 34/2014 Coll., amending and supplementing Act 220/2004 Coll., On the (Protection and Use of Agricultural Land). Soil is a complex system of abiotic and biotic components and is the result of soil-forming factors. It is created on the interface of the atmosphere, the lithosphere, the hydrosphere and the biosphere, which to a great extent influences its composition. In the soil-forming processes, abiotic and biotic environmental factors are applied together, and the result of their action is the abiotic-biotic component of the environment - soil. *The main abiotic factors* involved in soil formation include: parent (soil-forming) rock, relief, water and climatic conditions. The chemical composition of the soil depends primarily on the parent rock from which the soil originated, from the processes running in the soil and from the activity of man. Soil contains most oxygen (about 50%) and silicon (about 25%), other elements are mainly aluminum (clay), iron, calcium (limestone, gypsum), sodium, potassium, magnesium, hydrogen, titanium, in lesser amounts carbon, chlorine, phosphorus, sulfur and manganese. *Biotic agents* include soil edaphone. These factors are collectively called soil-forming factors. Edaphone is a living component of soil. It is a set of soil microorganisms, fungi, plants and animals. Soil organisms (geo bionti, edafonti) live in slots washed

out by air or water, especially in the surface layers of the soil. For humification processes, plants, bacteria, and mycophytes are the most important. The root system of higher plants ensures the mechanical movement of the soil and keeps it loose. Bacteria break down organic matter in the soil. The soil contains both autotrophic and heterotrophic bacteria. Bacteria can have diverse functions in the soil. Decomposition of animal, plant and microbial residues is performed by heterotrophic bacteria. Chemoautotrophic bacteria in the soil are predominantly represented by nitrifying bacteria and, to a lesser extent, sulfur-oxidizing bacteria. The most common microbial cells in the soil are single-cell prokaryotes. Despite their high concentration in soil, fungal biomass predominates over the biomass of bacteria. Soil bacterial flora is extremely diverse and is dominated by Gram-positive bacteria. Fungi dominate the soil in terms of biomass amount. They are eukaryotic and have a mycelial morphology consisting of mycelia that surrounds the multinuclear cytoplasm. They live in symbiosis with most plant roots, which are of great importance for regulating nutrient uptake, aquatic connections and ultimately the growth of a plant partner in this community. Soil spore production allows to some extent their survival under unfavorable soil conditions. Fungi also include many important plant pathogens. Bacteria, worms, insects and other animals process plant residues in healthy soil. In this way, soil is enriched with substances that are vital for plants. However, if the soil is acidified by acid rain, the animals cannot live in it. Dead plant residues remain lying on the ground, no nutrients are created for the animals, and the food chain breaks. *Soil contamination, causes, monitoring*: we consider soil to be one of the main components of the Earth's ecosphere. It forms the basis of the nutritional chain at the end of which man stands [2, 18]. The most important soil characteristic is fertility, the ability of the soil to provide plants with water, air, nutrients in optimal quantities throughout the vegetation [19]. The soil system is a very specific component and to some extent can effectively and naturally eliminate various foreign substances. Soil and ecosystem components - water and air - are basic indicators of pollution. The soil loses most due to contamination since its ability to eliminate the negative effects caused by the natural and anthropogenic activity of man become limited [20–22]. Major problem of consumer society is waste production. The issue of waste does not end with the disposal of waste in landfills. Precipitation waters that infiltrate through landfills are contaminated with waste materials. Such landfill leachates can then contaminate the soil or the bedrock where the landfill is located. Another factor that negatively affects soil environmental functions is the contamination of soil by water and air. Pollutants in air and water are mainly from industrial production. *Toxic heavy metals*, like biogenic metals, are present in the soil in two mobilities. They occur in the liquid phase as hydrated ions or as soluble organic and inorganic complexes. In the solid phase they are in the form of insoluble precipitates on the surface of organic and inorganic colloids in exchangeable and specifically absorbed form. A dynamic equilibrium is created between the various forms, in accordance with the characteristics of the system. If e.g., a large amount of toxic substance gets into the soil, absorption and precipitation reactions predominate. On the other hand, when the acidity of the soil increases, the number of mobile forms increases, i.e., the concentration of metal ions in solution increases. Contamination of the soil by sulfur dioxide exhales is leads to its *acidification.* Low pH causes increased mobility of cadmium and aluminum, which can intoxicate plants. Other contaminants also enter the soil through sedimentation: nitrogen oxides, lead, cadmium, arsenic, fly ash, chromium, nickel, organic compounds. Lead polluting soil comes mainly from automobile traffic. The source of cadmium is the burning of fossil fuels. The arsenic from the power plant ash dissolves well in the water and therefore does not accumulate in the topsoil but passes into the lower layers. Acidification of the soil in already contaminated areas

**43**

*Heavy Metals and the Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86876*

is particularly dangerous as heavy metal compounds are normally insoluble, but when mobilized, they can result in a serious environmental damage (*timed chemical bomb*). Soil is an important geochemical reservoir, which relatively easily accumulates heavy metals. They are removed only very slowly, by leaching processes into subsurface waters or by plant bioaccumulation. Soil is the starting point for the entry of risky elements into crops and through forage into animal products [23, 24]. Soil contamination with water occurs as a result of soil irrigation or rainfall activity. Erosion is one of the most serious problems threatening soil worldwide. The erosion is due to the spread of mountain farming, the excavation of forests, the deterioration of the soil's water regime, the plowing of grasslands, the artificial regulation of watercourses, the wrong land cultivation. The result of erosion is the drainage of soil parts, humus, nutrients, crop reduction. As reported by the authors [13, 15, 25, 26]. industrial emissions primarily affect the pollution of agricultural and forest land. Especially increased content of lead (Pb), zinc (Zn), tin (Sn), cadmium (Cd), aluminum (Al), copper (Cu), nickel (Ni), mercury (Hg), manganese (Mn), and arsenic (As) was found in the vicinity of metallurgical factories. All metals usually get into the soil, but increasingly those components that dominate the immission type. The most important metal pollutants of soil are mercury (Hg), cadmium (Cd) and lead (Pb), which are generally toxic to humans and animals [2, 3, 9, 16, 27].

**4.1 Health risks of environmental pollution, risk analysis, evaluation**

Increasingly polluted environment, preservatives, dyes and flavorings present in the food are heavily burdening the body. Pesticides for weed control, chemical fertilizers, and nitrates can be carcinogenic when getting into organism. Automobile exhaust gases, ozone, formaldehyde, wood disinfectants and preservatives, insecticides, paint solvents and the like contaminate air, damage the respiratory tract and weaken the immune system [26]. This is why methods for assessing health risks (e.g. questionnaires, risk assessment, analyses, diagrams, use of geographic information systems) are extremely important. *Risk Analysis* - [28] states that it is very important to determine the level of danger to human health and animals in a given location and at the same time to take account of future use of a respective area. In general, the principles of the health risk assessment, hazard determination and hazard identification, (evaluation of dose - response relationship, exposure evaluation & assessment, risk characterization are applied). In assessing the health risks and adverse effects of metals, it is important to evaluate not only their presence and overall concentration in the environment and in food, but also their chemical and mineral forms that affect their persistence and bioavailability. The effects of sudden metal uptake into organisms may have the character of *"acute disease".* Metals, with regard to the accumulation in target organs of the organism, cause disease manifestations after periods with different length (weeks to years) and the clinical picture has the character of "*chronic disease*" [11, 29]. *The aim of the assessment* is to determine the harmfulness of chemicals or other risk factors occurring on the site and to assess whether the substance or risk factor has the ability to damage the body. In general, this part of the risk assessment process describes the quantitative relationship between dose and extent of adverse effect (injury, disease, death). This step requires two basic types of extrapolation using different mathematical models. These are extrapolations - interspecific (experimental animal - human) and extrapolation to the low dose area [10]. At present, the *protection* of *environment* is seen as a necessary condition for the existence and further development of human society. It includes activities to prevent pollution or damage to the environment, respectively for the reduction and/or elimination of pollution. It is either general protection (air, soil, water), special protection (protected areas, plants, animals,)

#### *Heavy Metals and the Environment DOI: http://dx.doi.org/10.5772/intechopen.86876*

*Environmental Factors Affecting Human Health*

out by air or water, especially in the surface layers of the soil. For humification processes, plants, bacteria, and mycophytes are the most important. The root system of higher plants ensures the mechanical movement of the soil and keeps it loose. Bacteria break down organic matter in the soil. The soil contains both autotrophic and heterotrophic bacteria. Bacteria can have diverse functions in the soil. Decomposition of animal, plant and microbial residues is performed by heterotrophic bacteria. Chemoautotrophic bacteria in the soil are predominantly represented by nitrifying bacteria and, to a lesser extent, sulfur-oxidizing bacteria. The most common microbial cells in the soil are single-cell prokaryotes. Despite their high concentration in soil, fungal biomass predominates over the biomass of bacteria. Soil bacterial flora is extremely diverse and is dominated by Gram-positive bacteria. Fungi dominate the soil in terms of biomass amount. They are eukaryotic and have a mycelial morphology consisting of mycelia that surrounds the multinuclear cytoplasm. They live in symbiosis with most plant roots, which are of great importance for regulating nutrient uptake, aquatic connections and ultimately the growth of a plant partner in this community. Soil spore production allows to some extent their survival under unfavorable soil conditions. Fungi also include many important plant pathogens. Bacteria, worms, insects and other animals process plant residues in healthy soil. In this way, soil is enriched with substances that are vital for plants. However, if the soil is acidified by acid rain, the animals cannot live in it. Dead plant residues remain lying on the ground, no nutrients are created for the animals, and the food chain breaks. *Soil contamination, causes, monitoring*: we consider soil to be one of the main components of the Earth's ecosphere. It forms the basis of the nutritional chain at the end of which man stands [2, 18]. The most important soil characteristic is fertility, the ability of the soil to provide plants with water, air, nutrients in optimal quantities throughout the vegetation [19]. The soil system is a very specific component and to some extent can effectively and naturally eliminate various foreign substances. Soil and ecosystem components - water and air - are basic indicators of pollution. The soil loses most due to contamination since its ability to eliminate the negative effects caused by the natural and anthropogenic activity of man become limited [20–22]. Major problem of consumer society is waste production. The issue of waste does not end with the disposal of waste in landfills. Precipitation waters that infiltrate through landfills are contaminated with waste materials. Such landfill leachates can then contaminate the soil or the bedrock where the landfill is located. Another factor that negatively affects soil environmental functions is the contamination of soil by water and air. Pollutants in air and water are mainly from industrial production. *Toxic heavy metals*, like biogenic metals, are present in the soil in two mobilities. They occur in the liquid phase as hydrated ions or as soluble organic and inorganic complexes. In the solid phase they are in the form of insoluble precipitates on the surface of organic and inorganic colloids in exchangeable and specifically absorbed form. A dynamic equilibrium is created between the various forms, in accordance with the characteristics of the system. If e.g., a large amount of toxic substance gets into the soil, absorption and precipitation reactions predominate. On the other hand, when the acidity of the soil increases, the number of mobile forms increases, i.e., the concentration of metal ions in solution increases. Contamination of the soil by sulfur dioxide exhales is leads to its *acidification.* Low pH causes increased mobility of cadmium and aluminum, which can intoxicate plants. Other contaminants also enter the soil through sedimentation: nitrogen oxides, lead, cadmium, arsenic, fly ash, chromium, nickel, organic compounds. Lead polluting soil comes mainly from automobile traffic. The source of cadmium is the burning of fossil fuels. The arsenic from the power plant ash dissolves well in the water and therefore does not accumulate in the topsoil but passes into the lower layers. Acidification of the soil in already contaminated areas

**42**

is particularly dangerous as heavy metal compounds are normally insoluble, but when mobilized, they can result in a serious environmental damage (*timed chemical bomb*). Soil is an important geochemical reservoir, which relatively easily accumulates heavy metals. They are removed only very slowly, by leaching processes into subsurface waters or by plant bioaccumulation. Soil is the starting point for the entry of risky elements into crops and through forage into animal products [23, 24]. Soil contamination with water occurs as a result of soil irrigation or rainfall activity. Erosion is one of the most serious problems threatening soil worldwide. The erosion is due to the spread of mountain farming, the excavation of forests, the deterioration of the soil's water regime, the plowing of grasslands, the artificial regulation of watercourses, the wrong land cultivation. The result of erosion is the drainage of soil parts, humus, nutrients, crop reduction. As reported by the authors [13, 15, 25, 26]. industrial emissions primarily affect the pollution of agricultural and forest land. Especially increased content of lead (Pb), zinc (Zn), tin (Sn), cadmium (Cd), aluminum (Al), copper (Cu), nickel (Ni), mercury (Hg), manganese (Mn), and arsenic (As) was found in the vicinity of metallurgical factories. All metals usually get into the soil, but increasingly those components that dominate the immission type. The most important metal pollutants of soil are mercury (Hg), cadmium (Cd) and lead (Pb), which are generally toxic to humans and animals [2, 3, 9, 16, 27].

## **4.1 Health risks of environmental pollution, risk analysis, evaluation**

Increasingly polluted environment, preservatives, dyes and flavorings present in the food are heavily burdening the body. Pesticides for weed control, chemical fertilizers, and nitrates can be carcinogenic when getting into organism. Automobile exhaust gases, ozone, formaldehyde, wood disinfectants and preservatives, insecticides, paint solvents and the like contaminate air, damage the respiratory tract and weaken the immune system [26]. This is why methods for assessing health risks (e.g. questionnaires, risk assessment, analyses, diagrams, use of geographic information systems) are extremely important. *Risk Analysis* - [28] states that it is very important to determine the level of danger to human health and animals in a given location and at the same time to take account of future use of a respective area. In general, the principles of the health risk assessment, hazard determination and hazard identification, (evaluation of dose - response relationship, exposure evaluation & assessment, risk characterization are applied). In assessing the health risks and adverse effects of metals, it is important to evaluate not only their presence and overall concentration in the environment and in food, but also their chemical and mineral forms that affect their persistence and bioavailability. The effects of sudden metal uptake into organisms may have the character of *"acute disease".* Metals, with regard to the accumulation in target organs of the organism, cause disease manifestations after periods with different length (weeks to years) and the clinical picture has the character of "*chronic disease*" [11, 29]. *The aim of the assessment* is to determine the harmfulness of chemicals or other risk factors occurring on the site and to assess whether the substance or risk factor has the ability to damage the body. In general, this part of the risk assessment process describes the quantitative relationship between dose and extent of adverse effect (injury, disease, death). This step requires two basic types of extrapolation using different mathematical models. These are extrapolations - interspecific (experimental animal - human) and extrapolation to the low dose area [10]. At present, the *protection* of *environment* is seen as a necessary condition for the existence and further development of human society. It includes activities to prevent pollution or damage to the environment, respectively for the reduction and/or elimination of pollution. It is either general protection (air, soil, water), special protection (protected areas, plants, animals,)

or the protection of cultural monuments. *The creation of the environment* is understood as a purposeful human activity that is organized on a scientific basis, aiming at optimizing the natural and artificial components of the landscape. *The aim of environmental care* is to maintain or improve its quality with respect to all organisms, while respecting all principles of sustainable living. This environmental care is called environmentalism [7, 13, 30].

### **4.2 Heavy metals and their importance in environmental pollution, sources, form**

Heavy metals are among the common environmental pollutants resulting from both industrial and agricultural production [31]. They are not subject to biological degradation, and their levels are gradually increasing in the individual environmental components: water, air, foodstuffs [29, 32]. They are released into the environment from natural sources (weathering) and by erosion of some minerals and rocks. As stated by [33] the natural increased incidence of heavy metals and other risk elements is mainly in the areas of geochemical anomalies. Regarding pesticides (containing heavy metals), their use has been suspended and is no longer the source of this type of pollution. Metal production (their heat treatment), chemical, engineering, energy production, fossil fuel combustion, waste, food production flushing, fertilization, etc. are among the major *anthropogenic sources* of environmental pollution. As [34] report, metallurgy of ferrous and non-ferrous ores (the impact of non-ferrous ore metallurgy is predominant in mercury) contributes most to emissions of mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu) and zinc (Zn). Combustion of fossil fuels contributes significantly to the emissions of most heavy metals, glass production is a significant source of lead (Pb) and cadmium (Cd) emissions, and transport, despite the dynamic increase in the use of unleaded petrol, complements these sources. In the past, alkyl lead compounds (tetra-ethyl lead) were used as antiknock additives in gasoline, thereby increasing the concentration of lead in the air. Thus, pollutants are introduced into the environment from various sources and based on their physico-chemical properties. They are transported and participate in biochemical cycles in individual environmental components (air, water, soil, rocks, segments). [35] states that heavy metals constitute one of the most dangerous groups of pollutants. Their amount in the environment is given by content, quantity and movement in all spheres of the environment. The side effects of heavy metal emissions are dangerous, they usually get into the environment (the air) in an uncontrolled way. In the environment, they can occur as simple complexes with inorganic ligands (in the aqueous environment, the form of the metal is affected by physico-chemical properties: pH, temperature, ionic strength), as chelates with organic ligands (sorbed to solid surfaces), free metals. In the terrestrial environment, fate, bioavailability and mobility of metals are influenced by: soil type, oxidation–reduction processes and cationic solid phase capacity [36]. More detailed information on the specific effects of individual heavy metals on cells, tissues, and organs of animals is obtained and validated within laboratory animal experiments. However, the results of the experimental application cannot be considered generally valid. Mostly, the experiment only works with the substance being studied individually, which does not occur alone in the environment. All animal species may not respond to the toxic substance in the same way. In the response of the organism to the action of a toxic substance, the overall momentary state of the organism, its life phase and gender are important. Taking all these factors into account during an experiment is almost

**45**

ent levels of signal transduction processes in cells.

*Heavy Metals and the Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86876*

impossible. Therefore, despite the systematic research, there is still some concern over formulating the environmental and hazardous concentrations of these substances. However, these doubts do not justify the presence of heavy metals in the environment being taken lightly or underestimated. The combination of overexploitation of natural resources, coercive forced population growth and economic developments, as well as a lack of government regulations can increase the flow of toxic metals into the environment in all countries. By 2010, a significant increase in emissions of mercury (Hg), cadmium (Cd), copper (Cu) and a decrease in lead (Pb) emissions and deposition was expected in Europe [2]. Heavy metals cause a wide range of toxic biochemical effects and thus adversely affect organs and systems in humans and animals [37, 38]. Therefore, they pose a serious risk to health regardless of the source from which they enter the body. Some heavy metals (e.g., manganese, copper, zinc) are needed for physiological processes, but other toxic heavy metals (especially cadmium, mercury, lead) are environmental pollutants [39] and do not have any known physiological roles. Conversely, they may adversely affect health [40] and thus induce a variety of adverse effects including reproductive disorders [41] nutritional deficiencies, endocrine disorders [42, 43] or immunodeficiency disorders; they can induce tumor formation and other health-damaging chronic conditions [32, 44]. Currently, there is also a strong focus on low-dose exposures (environmentally relevant concentrations) of these metals that may affect human and animal reproductive health [3, 45, 46]. Ecologists and environmentalists duly address this issue and take into account the contexts that have not yet been considered. Even if the concentrations of heavy metals with regard to the health safety of living organisms are limited within the monitored areas, environmentalists are the ones drawing attention to many natural processes that cause the concentration of toxic elements to become a real danger. Certain metals are needed for normal body function. They are part of the enzymes and take different roles in metabolic processes and electron transfer - manganese (Mn), copper (Cu), nickel (Ni), molybdenum (Mo), cobalt (Co), iron (Fe), zinc (Zn), however, at higher concentrations they can already become toxic. Heavy metals are characterized by varying degrees of toxicity and different effects on living organisms. The subject of world monitoring is strongly toxic elements - mercury (Hg), cadmium (Cd), lead (Pb), arsenic (As), which have almost no purpose in the organism [47]. Metals are found bound in various inorganic compounds, but can also enter complex organic systems. They are persistent, non-degradable, biologically active with high bioaccumulation potential. They form a natural part of the Earth's surface composition and therefore occur everywhere in various concentrations. The natural balance of elements is also impaired by human activity. Together with the development of modern technology, production and consumption of metals and metalloids are growing rapidly, too. This is particularly true for non-ferrous metals, some of which have until recently been produced in incomparably lower amounts (e.g. laboratory scale) beryllium (Be), titanium (Tl) gallium (Ga), selenium (Se), molybdenum (Mo), wolfram (W). Also, the production of classic colored metals which are gradually finding new types of applications, is increasing,. This is especially true for aluminum (Al), lead (Pb), nickel (Ni), chromium (Cr), antimony (Sb), mercury (Hg). Increasing the concentration of the above metals in the environment - air, water, soil and foodstuffs, is a serious hygiene problem and its scale is still becoming larger [23, 34, 48–50]. In general, metals are highly reactive elements which, on the one hand, are essential (they are components of some enzymes), on the other hand they are capable of damaging different enzymes or interfering with differ-

#### *Heavy Metals and the Environment DOI: http://dx.doi.org/10.5772/intechopen.86876*

*Environmental Factors Affecting Human Health*

called environmentalism [7, 13, 30].

**form**

or the protection of cultural monuments. *The creation of the environment* is understood as a purposeful human activity that is organized on a scientific basis, aiming at optimizing the natural and artificial components of the landscape. *The aim of environmental care* is to maintain or improve its quality with respect to all organisms, while respecting all principles of sustainable living. This environmental care is

**4.2 Heavy metals and their importance in environmental pollution, sources,**

Heavy metals are among the common environmental pollutants resulting from both industrial and agricultural production [31]. They are not subject to biological degradation, and their levels are gradually increasing in the individual environmental components: water, air, foodstuffs [29, 32]. They are released into the environment from natural sources (weathering) and by erosion of some minerals and rocks. As stated by [33] the natural increased incidence of heavy metals and other risk elements is mainly in the areas of geochemical anomalies. Regarding pesticides (containing heavy metals), their use has been suspended and is no longer the source of this type of pollution. Metal production (their heat treatment), chemical, engineering, energy production, fossil fuel combustion, waste, food production flushing, fertilization, etc. are among the major *anthropogenic sources* of environmental pollution. As [34] report, metallurgy of ferrous and non-ferrous ores (the impact of non-ferrous ore metallurgy is predominant in mercury) contributes most to emissions of mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu) and zinc (Zn). Combustion of fossil fuels contributes significantly to the emissions of most heavy metals, glass production is a significant source of lead (Pb) and cadmium (Cd) emissions, and transport, despite the dynamic increase in the use of unleaded petrol, complements these sources. In the past, alkyl lead compounds (tetra-ethyl lead) were used as antiknock additives in gasoline, thereby increasing the concentration of lead in the air. Thus, pollutants are introduced into the environment from various sources and based on their physico-chemical properties. They are transported and participate in biochemical cycles in individual environmental components (air, water, soil, rocks, segments). [35] states that heavy metals constitute one of the most dangerous groups of pollutants. Their amount in the environment is given by content, quantity and movement in all spheres of the environment. The side effects of heavy metal emissions are dangerous, they usually get into the environment (the air) in an uncontrolled way. In the environment, they can occur as simple complexes with inorganic ligands (in the aqueous environment, the form of the metal is affected by physico-chemical properties: pH, temperature, ionic strength), as chelates with organic ligands (sorbed to solid surfaces), free metals. In the terrestrial environment, fate, bioavailability and mobility of metals are influenced by: soil type, oxidation–reduction processes and cationic solid phase capacity [36]. More detailed information on the specific effects of individual heavy metals on cells, tissues, and organs of animals is obtained and validated within laboratory animal experiments. However, the results of the experimental application cannot be considered generally valid. Mostly, the experiment only works with the substance being studied individually, which does not occur alone in the environment. All animal species may not respond to the toxic substance in the same way. In the response of the organism to the action of a toxic substance, the overall momentary state of the organism, its life phase and gender are important. Taking all these factors into account during an experiment is almost

**44**

impossible. Therefore, despite the systematic research, there is still some concern over formulating the environmental and hazardous concentrations of these substances. However, these doubts do not justify the presence of heavy metals in the environment being taken lightly or underestimated. The combination of overexploitation of natural resources, coercive forced population growth and economic developments, as well as a lack of government regulations can increase the flow of toxic metals into the environment in all countries. By 2010, a significant increase in emissions of mercury (Hg), cadmium (Cd), copper (Cu) and a decrease in lead (Pb) emissions and deposition was expected in Europe [2]. Heavy metals cause a wide range of toxic biochemical effects and thus adversely affect organs and systems in humans and animals [37, 38]. Therefore, they pose a serious risk to health regardless of the source from which they enter the body. Some heavy metals (e.g., manganese, copper, zinc) are needed for physiological processes, but other toxic heavy metals (especially cadmium, mercury, lead) are environmental pollutants [39] and do not have any known physiological roles. Conversely, they may adversely affect health [40] and thus induce a variety of adverse effects including reproductive disorders [41] nutritional deficiencies, endocrine disorders [42, 43] or immunodeficiency disorders; they can induce tumor formation and other health-damaging chronic conditions [32, 44]. Currently, there is also a strong focus on low-dose exposures (environmentally relevant concentrations) of these metals that may affect human and animal reproductive health [3, 45, 46]. Ecologists and environmentalists duly address this issue and take into account the contexts that have not yet been considered. Even if the concentrations of heavy metals with regard to the health safety of living organisms are limited within the monitored areas, environmentalists are the ones drawing attention to many natural processes that cause the concentration of toxic elements to become a real danger. Certain metals are needed for normal body function. They are part of the enzymes and take different roles in metabolic processes and electron transfer - manganese (Mn), copper (Cu), nickel (Ni), molybdenum (Mo), cobalt (Co), iron (Fe), zinc (Zn), however, at higher concentrations they can already become toxic. Heavy metals are characterized by varying degrees of toxicity and different effects on living organisms. The subject of world monitoring is strongly toxic elements - mercury (Hg), cadmium (Cd), lead (Pb), arsenic (As), which have almost no purpose in the organism [47]. Metals are found bound in various inorganic compounds, but can also enter complex organic systems. They are persistent, non-degradable, biologically active with high bioaccumulation potential. They form a natural part of the Earth's surface composition and therefore occur everywhere in various concentrations. The natural balance of elements is also impaired by human activity. Together with the development of modern technology, production and consumption of metals and metalloids are growing rapidly, too. This is particularly true for non-ferrous metals, some of which have until recently been produced in incomparably lower amounts (e.g. laboratory scale) beryllium (Be), titanium (Tl) gallium (Ga), selenium (Se), molybdenum (Mo), wolfram (W). Also, the production of classic colored metals which are gradually finding new types of applications, is increasing,. This is especially true for aluminum (Al), lead (Pb), nickel (Ni), chromium (Cr), antimony (Sb), mercury (Hg). Increasing the concentration of the above metals in the environment - air, water, soil and foodstuffs, is a serious hygiene problem and its scale is still becoming larger [23, 34, 48–50]. In general, metals are highly reactive elements which, on the one hand, are essential (they are components of some enzymes), on the other hand they are capable of damaging different enzymes or interfering with different levels of signal transduction processes in cells.

#### **4.3 Heavy metals and food chain**

There is a comprehensive versatile and complex network of food chains in nature. They are interconnected, while the function of the individual elements of the food chains may vary. This causes the symbiotic organism to become dysbiotic, useful changes to harmful, or pathogenic [51]. The common population is also contaminated with the food chain [52] since it has a major impact on human (but also animal) nutrition, lifestyle and life expressions. Animals are much more exposed to the impact of the geochemical environment than humans, as they serve as effective buffers in the nutritional chain, in reducing the adverse effects of the environment on the consumer. According to [53] optimizing the animal nutrition can affect the human food chain. Most heavy metals get into the organism by plant or animal food (the load from air or drinking water is significantly lower). They are converted either into harmless metabolites (detoxification) that are easily excreted, or harmful, reactive products are formed. [54] states that the increased content of especially cadmium (Cd), mercury (Hg), chromium (Cr), arsenic (As), lead (Pb) and nickel (Ni) in agricultural soils may pose a potential risk of contamination of agricultural production. In most countries, including, the applicable legislation determines the maximum permissible concentrations (MPCs) for individual heavy metals (drinking water, air, foodstuffs of plant or animal origin). Therefore, the protection of the food chain from heavy metal contamination, and its follow-up checks are considered to be important in terms of health security. As reported by [55] food safety is a set of measures (animal health and welfare section, food and feed sector) and with their implementation, the safety of all components within the food chain is ensured. According to [56] the occurrence of contaminants in environmental components and in agricultural and food production is monitored through random check-ups and regular monitoring. The relationship between animal health, human health and the environment has been known for a long time. Potential contaminants and their total amount for both veterinary and public health are broad and vary according to their source, chemical nature and mechanism of action on biological systems. [57] state that the prevention of human and animal health from chemical risks implies their control throughout the food chain - field-table. Food quality control with the participation of state health surveillance in the Slovak Republic is one of the essential tasks of food surveillance and the limits of foreign substances in food commodities are harmonized in accordance with the limits of the European Union [58–61].

#### **4.4 Impact of selected heavy metals-Hg and Cd on humans, animals and the environment**

The transport of heavy metals in the atmosphere and their subsequent deposition depends on the following factors: the form in which the metal is found to escape into the atmosphere (solid or gaseous phase), their chemical reaction in the atmosphere, the height and location of the point source of emission, local geographic conditions, speed and direction of wind, rain washing and other meteorological requirements [12]. Pollution of the environment is now a global phenomenon, not excluding the territory of Slovakia and contributes to the deterioration of living and working conditions [2]. Recently, great attention has been paid to the impact of toxic heavy metals and their compounds (especially mercury, cadmium, lead) on human and animal health, which are considered to be dangerous and non-degradable contaminants in the environment. However, a suitable marker for early diagnosis of heavy metal exposure (including drinking water sources) has not yet been developed, which is perceived as a relatively serious problem [62].

**47**

*Heavy Metals and the Environment*

**occurrence**

*DOI: http://dx.doi.org/10.5772/intechopen.86876*

As reported by several authors [44, 63, 64] the main consequence of the negative effect of environmental contaminants is the disruption of the optimal immune reactivity of the organism, the occurrence of allergies, increased susceptibility to pathogenic agents, higher occurrence of tumors, affecting reproduction. History shows us a number of global industrial accidents pointing to the negative effects. An important part in creating a good living environment for both humans and livestock is active health creation. It is based on two fundamental phenomena. It is a principle of complexity of measures, respecting variability of the effects of relationships and factors - the internal and external environment of the organism [7].

**4.5 Cadmium - sources of cadmium in the environment, the effects of its**

cadmium in the soil ranges from 0.01 to 0.7 mg.kg<sup>−</sup><sup>1</sup>

The main sources of cadmium include volcanic activity, weathering of rocks, or forest fires [65]. It gets into the environment by mining and processing of fossil fuels, ferrous and non-ferrous ores, limestone, in cement production [66]. It can be found in Cd-Ni batteries, stabilizers of plastics, home appliances. Cadmium also occurs in synthetic superphosphate and in naturally occurring superphosphates. Cadmium (yellow-orange) paints are added to coatings, gums, textiles, glass and ceramics. Along with zinc (Zn), it occurs in ores and soil at a ratio of 1:100 to 1:1000. It is usually found in the form of cadmium sulfide (CdS) in ores which also contain lead (Pb), zinc (Zn) and copper (Cu). Unlike mercury, it is not subject to biotransformation and cannot be released as an alkyl derivative from the organism. It is now widely used for its anticorrosive effects and serves as a base for electroplating and nickel plating. It is also widely used in making jewelry. It can enter the atmosphere due to poor waste incineration technology (higher cadmium exposure is near the smelter where ores blended with Cd are melted) or oil products [67]. According to WHO, the largest part of cadmium is bound to fine particles (<1 μm) in air, which can then spread up to 1–2 km. Thus, cadmium builds up in soil, water and then enters the food chain. In soil and in some plants, accumulation occurs especially at low soil pH (e.g. leaves, rice). In agricultural soils, the accumulation of cadmium may be associated with the application of (phosphate fertilizers, sewage sludge, some fungicides [66, 68, 69].). The concentration of

the 0–5 cm layer. With increasing depth there is a decrease in its concentration. In

transformed into a solution and its occurrence is in the form of Cd2+. According to [70], cadmium intake by plants increases with the presence of chlorine in the soil and the content is also significantly affected by soil microorganisms. The way of farming, the time of harvesting the crop and also the environment (climate) affects the cadmium transfer into the plants. This suggests that increased cadmium content in soil is the result of increased cadmium absorption by plants, but, as [71] states, the bioavailability of cadmium also depends on soil solution composition, soil pH, and redox potential. Soil has the ability to somewhat eliminate the negative effects of pollution [22]. Compared to other environmental components, soil status is exceptional. Air and water may move (dilution occurs), and if the source of pollution ceases to be active, there is also a limitation or total elimination of pollution. However, in case of soil contamination by risk elements, we have to realize that this is an irreversible process, it cannot be observed immediately and therefore it is all the more serious. In waters, cadmium accompanies zinc at substantially lower concentrations. According to the higher cadmium content (Cd) has been repeatedly detected in water flowing right by zinc mines. The solubility in water is determined by the solubility of CdCO3 and Cd (OH)2. It is generally presumed that people

the process of weathering rocks (content not exceeding 0.3 mg.kg<sup>−</sup><sup>1</sup>

and is most cumulative in

), it is easily

#### *Heavy Metals and the Environment DOI: http://dx.doi.org/10.5772/intechopen.86876*

*Environmental Factors Affecting Human Health*

There is a comprehensive versatile and complex network of food chains in nature. They are interconnected, while the function of the individual elements of the food chains may vary. This causes the symbiotic organism to become dysbiotic, useful changes to harmful, or pathogenic [51]. The common population is also contaminated with the food chain [52] since it has a major impact on human (but also animal) nutrition, lifestyle and life expressions. Animals are much more exposed to the impact of the geochemical environment than humans, as they serve as effective buffers in the nutritional chain, in reducing the adverse effects of the environment on the consumer. According to [53] optimizing the animal nutrition can affect the human food chain. Most heavy metals get into the organism by plant or animal food (the load from air or drinking water is significantly lower). They are converted either into harmless metabolites (detoxification) that are easily excreted, or harmful, reactive products are formed. [54] states that the increased content of especially cadmium (Cd), mercury (Hg), chromium (Cr), arsenic (As), lead (Pb) and nickel (Ni) in agricultural soils may pose a potential risk of contamination of agricultural production. In most countries, including, the applicable legislation determines the maximum permissible concentrations (MPCs) for individual heavy metals (drinking water, air, foodstuffs of plant or animal origin). Therefore, the protection of the food chain from heavy metal contamination, and its follow-up checks are considered to be important in terms of health security. As reported by [55] food safety is a set of measures (animal health and welfare section, food and feed sector) and with their implementation, the safety of all components within the food chain is ensured. According to [56] the occurrence of contaminants in environmental components and in agricultural and food production is monitored through random check-ups and regular monitoring. The relationship between animal health, human health and the environment has been known for a long time. Potential contaminants and their total amount for both veterinary and public health are broad and vary according to their source, chemical nature and mechanism of action on biological systems. [57] state that the prevention of human and animal health from chemical risks implies their control throughout the food chain - field-table. Food quality control with the participation of state health surveillance in the Slovak Republic is one of the essential tasks of food surveillance and the limits of foreign substances in food commodities are harmonized in accordance with the limits of the European

**4.4 Impact of selected heavy metals-Hg and Cd on humans, animals and the**

The transport of heavy metals in the atmosphere and their subsequent deposition depends on the following factors: the form in which the metal is found to escape into the atmosphere (solid or gaseous phase), their chemical reaction in the atmosphere, the height and location of the point source of emission, local geographic conditions, speed and direction of wind, rain washing and other meteorological requirements [12]. Pollution of the environment is now a global phenomenon, not excluding the territory of Slovakia and contributes to the deterioration of living and working conditions [2]. Recently, great attention has been paid to the impact of toxic heavy metals and their compounds (especially mercury, cadmium, lead) on human and animal health, which are considered to be dangerous and non-degradable contaminants in the environment. However, a suitable marker for early diagnosis of heavy metal exposure (including drinking water sources) has not yet been developed, which is perceived as a relatively serious problem [62].

**4.3 Heavy metals and food chain**

**46**

Union [58–61].

**environment**

As reported by several authors [44, 63, 64] the main consequence of the negative effect of environmental contaminants is the disruption of the optimal immune reactivity of the organism, the occurrence of allergies, increased susceptibility to pathogenic agents, higher occurrence of tumors, affecting reproduction. History shows us a number of global industrial accidents pointing to the negative effects. An important part in creating a good living environment for both humans and livestock is active health creation. It is based on two fundamental phenomena. It is a principle of complexity of measures, respecting variability of the effects of relationships and factors - the internal and external environment of the organism [7].

## **4.5 Cadmium - sources of cadmium in the environment, the effects of its occurrence**

The main sources of cadmium include volcanic activity, weathering of rocks, or forest fires [65]. It gets into the environment by mining and processing of fossil fuels, ferrous and non-ferrous ores, limestone, in cement production [66]. It can be found in Cd-Ni batteries, stabilizers of plastics, home appliances. Cadmium also occurs in synthetic superphosphate and in naturally occurring superphosphates. Cadmium (yellow-orange) paints are added to coatings, gums, textiles, glass and ceramics. Along with zinc (Zn), it occurs in ores and soil at a ratio of 1:100 to 1:1000. It is usually found in the form of cadmium sulfide (CdS) in ores which also contain lead (Pb), zinc (Zn) and copper (Cu). Unlike mercury, it is not subject to biotransformation and cannot be released as an alkyl derivative from the organism. It is now widely used for its anticorrosive effects and serves as a base for electroplating and nickel plating. It is also widely used in making jewelry. It can enter the atmosphere due to poor waste incineration technology (higher cadmium exposure is near the smelter where ores blended with Cd are melted) or oil products [67]. According to WHO, the largest part of cadmium is bound to fine particles (<1 μm) in air, which can then spread up to 1–2 km. Thus, cadmium builds up in soil, water and then enters the food chain. In soil and in some plants, accumulation occurs especially at low soil pH (e.g. leaves, rice). In agricultural soils, the accumulation of cadmium may be associated with the application of (phosphate fertilizers, sewage sludge, some fungicides [66, 68, 69].). The concentration of cadmium in the soil ranges from 0.01 to 0.7 mg.kg<sup>−</sup><sup>1</sup> and is most cumulative in the 0–5 cm layer. With increasing depth there is a decrease in its concentration. In the process of weathering rocks (content not exceeding 0.3 mg.kg<sup>−</sup><sup>1</sup> ), it is easily transformed into a solution and its occurrence is in the form of Cd2+. According to [70], cadmium intake by plants increases with the presence of chlorine in the soil and the content is also significantly affected by soil microorganisms. The way of farming, the time of harvesting the crop and also the environment (climate) affects the cadmium transfer into the plants. This suggests that increased cadmium content in soil is the result of increased cadmium absorption by plants, but, as [71] states, the bioavailability of cadmium also depends on soil solution composition, soil pH, and redox potential. Soil has the ability to somewhat eliminate the negative effects of pollution [22]. Compared to other environmental components, soil status is exceptional. Air and water may move (dilution occurs), and if the source of pollution ceases to be active, there is also a limitation or total elimination of pollution. However, in case of soil contamination by risk elements, we have to realize that this is an irreversible process, it cannot be observed immediately and therefore it is all the more serious. In waters, cadmium accompanies zinc at substantially lower concentrations. According to the higher cadmium content (Cd) has been repeatedly detected in water flowing right by zinc mines. The solubility in water is determined by the solubility of CdCO3 and Cd (OH)2. It is generally presumed that people

(but also animals) are the most sensitive cadmium intake group when environment is concerned. The main source of cadmium intake for humans and animals is food, feed and beverages. It is estimated that the average daily dietary intake of cadmium is 50 μg. Up to 25% of the daily intake is retained in the body. The content in dairy products is higher. The lethal dose for oral intake is 350–8900 μg [11]. **The impact of the toxic effects of cadmium on the organism:** Relative the toxic effect, cadmium is one of the elements that is of great concern for its toxicity and widespread environmental impact. In humans, the main source of Cd exposure is food [72] and the bioavailability of cadmium from food is an important determinant of its potential risk. Cadmium is one of the 10 most toxic substances for human and animal health [39, 73]. Cigarette smoking is also an important source of cadmium accumulation in the body. As reported by author [37] cadmium can cause functional and morphological changes in organs and tissues, and is also strongly neurotoxic. When the exposure to cadmium in environmental components is short term, there may be no health consequences, but from the perspective of long-term exposure (individuals who are more sensitive to toxic effects - infants and children) certain symptoms may occur [70]. The detoxification of the organism is slow (cadmium is characterized by a high accumulation coefficient) and there is a danger of chronic intoxication. Chemically, cadmium is very similar to zinc (it is a part of food), it has an important role for the proper development and health of the organism. However, the similar chemical form of these elements can cause problems as cadmium easily enters various enzymatic reactions instead of zinc, and biochemical processes take place in a different way (e.g., blocking the insulin cycle) and serious health complications occur [3, 74]. Cadmium gets into the organism in three ways: by inhalation, gastrointestinal tract and absorption through the skin. According to WHO, 50–2600 tons of cadmium are emitted annually from natural resources. The atmosphere is polluted by 3300–12,500 tons annually through human activity. In order to eliminate the negative effect on the living organism, [75] recommends a concentration of 5 ng.m<sup>−</sup><sup>3</sup> as a non-carcinogenic cadmium limit in the air. Current levels in rural areas usually do not exceed 0.4 ng.m<sup>−</sup><sup>3</sup> , and in cities they range from 0.2 to 2.5 ng.m<sup>−</sup><sup>3</sup> . According to in the vicinity of certain industrial agglomerations, this concentration can be significantly higher. WHO has determined a provisional tolerable weekly intake (PTWI) for cadmium at 7 μg.kg<sup>−</sup><sup>1</sup> of body weight. Since food is a major source of cadmium for most of the population, attention has also been paid to its quality as well as to the reduction of cadmium contamination of the environment. With an average absorption of about 5% of the amount received, about 0.5–1 μg of cadmium is retained daily in the organism. Based on epidemiological studies, there has been an increase in lung cancer and prostate cancer in longterm cadmium inhalation. In hazardous operations, inhalation intake is currently strictly controlled. The human lethal dose is 0.3–8.9 g. IARC [100] (International Agency for Research on Cancer) classifies Cd as the first category carcinogen for humans and animals.

#### **4.6 Mercury - sources of mercury in the environment, the effects of mercury**

Mercury is commonly found in the natural environment as it is a part of the Earth's crust. Its origin can be geogenic and anthropogenic. Mercury gets into the environment during its production and processing of products (production of electrodes, electrical equipment, dyes, measuring and control equipment, use in dentistry, chemical laboratories, etc.). In a year, this is estimated at 10,000–30,000 tons of mercury; and it gets into the environment by evaporating from the surface of the Earth and the oceans (vapor of metallic mercury, volatile organic compounds), [48]. The conversion of mercury (present in the form of ions) in a volatile

**49**

*Heavy Metals and the Environment*

atmosphere, and 2909 × 106

g.year<sup>−</sup><sup>1</sup>

sphere (amount of about 18 mg.m<sup>−</sup><sup>3</sup>

data, 5207 × 106

0.02–03 mg.kg<sup>−</sup><sup>1</sup>

within the range of 0.02–0.2 mg.kg<sup>−</sup><sup>1</sup>

year<sup>−</sup><sup>1</sup>

(310 × 106

*DOI: http://dx.doi.org/10.5772/intechopen.86876*

is the combustion of fossil fuels (1422 × 106

), waste management (187 × 106

form can theoretically occur in three ways: by chemical reaction to elemental mercury (not previously found in nature), by reduction to elemental mercury by microorganisms, plants, animals, and by biotransformation to more volatile

g (total 8116 × 106

), cement production (236 × 106

mercury emissions from natural resources are estimated at 3.0 × 106

living in relatively uncontaminated areas should be below 0.5 gg<sup>−</sup><sup>1</sup>

tion of mercury in the air ranges from 1 to 5 mg.m<sup>−</sup><sup>3</sup>

human activity are in the range of 0.1–0.4 mg.kg<sup>−</sup><sup>1</sup>

enterprises and crematoria up to 1.8 mg.kg<sup>−</sup><sup>1</sup>

organo-mercury compounds (alkyl compounds), [76]. According to the most recent

sources. The main anthropogenic sources by which mercury enters the atmosphere

g.year<sup>−</sup><sup>1</sup>

average mercury (Hg) content in the Earth's crust is about 0.067 ppm. *Air, water, soil* - elemental mercury vapors released from the Earth's crust rise to the atmo-

in cities. The enrichment of soils with mercury is caused by the burning of coal, the occurrence of cinnabar deposits, but also by applying mercury-based fungicides. The use of sewage and urban sludge and fertilizers is also a source of mercury soil pollution. However, this is not just about soil contamination, but also about secondary effect on vegetation growing on it [81]. Mercury gets into the soil in the range of

content of total mercury is higher in woody plants (the value exceeds 0.12 mg.kg<sup>−</sup><sup>1</sup>

use of mercury and its compounds has spread rapidly, and this fact cannot remain without consequences for: the environment, living organisms, including humans and animals. Therefore it is important to create favorable living conditions also for livestock (active health creation) based on the fundamental phenomena - complexity of measures and respect for the variability of the effects of relationships and factors between the internal and external environment [7]. **Effects of toxic action of mercury on the organism:** Regarding the effects of toxic effects on the organism, mercury is given a relatively high attention. Its toxicity depends on the physical properties of the individual forms. However, there are differences among them, based on the way of exposure, the metabolism itself, the way of excretion. It is known that the more mobile the form of mercury is, the more toxic it becomes. These properties are due to the structure of the molecule (e.g., behavior in biosystems, stability, excretion rates, etc.) [49, 85]. The negative impact not only on the health of people but also on the health and the performance of the animals results from an increased incidence of mercury, especially in polluted areas. The hygienic quality of animal products is lower, the content of toxic elements in meat and dairy

[11, 83, 84]. The natural content in the soil is from several, up to tens of μg.kg<sup>−</sup><sup>1</sup>

. The concentration of mercury in uncontaminated soils should be

[82]. Average concentrations affected by

and from there the compounds get into the water reservoirs by rain. Divalent mercury in the sediments at the bottom of the seas and lakes is methylated to methyl mercury by the action of microorganisms. It enters the food chain - phytoplankton - zooplankton - small fish - big fish. At the top of this chain are animals (that feed on fish), including humans. Within this chain, the process of bioaccumulation of ethylmercury occurs. As reported by [11, 78], its concentration is gradually increasing, with the values at the top of the chain about a million times higher than the concentration of methylmercury in the surrounding water. In general, large and longer-living fish (shark, tuna, mackerel, pike) also contain more mercury [48, 79, 80]. Under "European Commission Decision 93/351", the value of Hg in the meat of fish

g of mercury is released from the natural sources annually into the

g.year<sup>−</sup><sup>1</sup>

), where they are oxidized to divalent mercury

g.year<sup>−</sup><sup>1</sup>

g) of mercury from anthropogenic

), gold mining (400 × 106

), production of non-ferrous metals

)[34, 77]. Global

g.year<sup>−</sup><sup>1</sup>

.The concentra-

)

. The

in rural areas and 7–10 mg.m<sup>−</sup><sup>3</sup>

, and in the vicinity of industrial

, in the third of Slovakia's territory the

g.

. The

#### *Heavy Metals and the Environment DOI: http://dx.doi.org/10.5772/intechopen.86876*

*Environmental Factors Affecting Human Health*

concentration of 5 ng.m<sup>−</sup><sup>3</sup>

0.2 to 2.5 ng.m<sup>−</sup><sup>3</sup>

humans and animals.

levels in rural areas usually do not exceed 0.4 ng.m<sup>−</sup><sup>3</sup>

tolerable weekly intake (PTWI) for cadmium at 7 μg.kg<sup>−</sup><sup>1</sup>

(but also animals) are the most sensitive cadmium intake group when environment is concerned. The main source of cadmium intake for humans and animals is food, feed and beverages. It is estimated that the average daily dietary intake of cadmium is 50 μg. Up to 25% of the daily intake is retained in the body. The content in dairy products is higher. The lethal dose for oral intake is 350–8900 μg [11]. **The impact of the toxic effects of cadmium on the organism:** Relative the toxic effect, cadmium is one of the elements that is of great concern for its toxicity and widespread environmental impact. In humans, the main source of Cd exposure is food [72] and the bioavailability of cadmium from food is an important determinant of its potential risk. Cadmium is one of the 10 most toxic substances for human and animal health [39, 73]. Cigarette smoking is also an important source of cadmium accumulation in the body. As reported by author [37] cadmium can cause functional and morphological changes in organs and tissues, and is also strongly neurotoxic. When the exposure to cadmium in environmental components is short term, there may be no health consequences, but from the perspective of long-term exposure (individuals who are more sensitive to toxic effects - infants and children) certain symptoms may occur [70]. The detoxification of the organism is slow (cadmium is characterized by a high accumulation coefficient) and there is a danger of chronic intoxication. Chemically, cadmium is very similar to zinc (it is a part of food), it has an important role for the proper development and health of the organism. However, the similar chemical form of these elements can cause problems as cadmium easily enters various enzymatic reactions instead of zinc, and biochemical processes take place in a different way (e.g., blocking the insulin cycle) and serious health complications occur [3, 74]. Cadmium gets into the organism in three ways: by inhalation, gastrointestinal tract and absorption through the skin. According to WHO, 50–2600 tons of cadmium are emitted annually from natural resources. The atmosphere is polluted by 3300–12,500 tons annually through human activity. In order to eliminate the negative effect on the living organism, [75] recommends a

as a non-carcinogenic cadmium limit in the air. Current

. According to in the vicinity of certain industrial agglomerations,

this concentration can be significantly higher. WHO has determined a provisional

food is a major source of cadmium for most of the population, attention has also been paid to its quality as well as to the reduction of cadmium contamination of the environment. With an average absorption of about 5% of the amount received, about 0.5–1 μg of cadmium is retained daily in the organism. Based on epidemiological studies, there has been an increase in lung cancer and prostate cancer in longterm cadmium inhalation. In hazardous operations, inhalation intake is currently strictly controlled. The human lethal dose is 0.3–8.9 g. IARC [100] (International Agency for Research on Cancer) classifies Cd as the first category carcinogen for

**4.6 Mercury - sources of mercury in the environment, the effects of mercury**

Mercury is commonly found in the natural environment as it is a part of the Earth's crust. Its origin can be geogenic and anthropogenic. Mercury gets into the environment during its production and processing of products (production of electrodes, electrical equipment, dyes, measuring and control equipment, use in dentistry, chemical laboratories, etc.). In a year, this is estimated at 10,000–30,000 tons of mercury; and it gets into the environment by evaporating from the surface of the Earth and the oceans (vapor of metallic mercury, volatile organic compounds), [48]. The conversion of mercury (present in the form of ions) in a volatile

, and in cities they range from

of body weight. Since

**48**

form can theoretically occur in three ways: by chemical reaction to elemental mercury (not previously found in nature), by reduction to elemental mercury by microorganisms, plants, animals, and by biotransformation to more volatile organo-mercury compounds (alkyl compounds), [76]. According to the most recent data, 5207 × 106 g of mercury is released from the natural sources annually into the atmosphere, and 2909 × 106 g (total 8116 × 106 g) of mercury from anthropogenic sources. The main anthropogenic sources by which mercury enters the atmosphere is the combustion of fossil fuels (1422 × 106 g.year<sup>−</sup><sup>1</sup> ), gold mining (400 × 106 g. year<sup>−</sup><sup>1</sup> ), waste management (187 × 106 g.year<sup>−</sup><sup>1</sup> ), production of non-ferrous metals (310 × 106 g.year<sup>−</sup><sup>1</sup> ), cement production (236 × 106 g.year<sup>−</sup><sup>1</sup> )[34, 77]. Global mercury emissions from natural resources are estimated at 3.0 × 106 g.year<sup>−</sup><sup>1</sup> . The average mercury (Hg) content in the Earth's crust is about 0.067 ppm. *Air, water, soil* - elemental mercury vapors released from the Earth's crust rise to the atmosphere (amount of about 18 mg.m<sup>−</sup><sup>3</sup> ), where they are oxidized to divalent mercury and from there the compounds get into the water reservoirs by rain. Divalent mercury in the sediments at the bottom of the seas and lakes is methylated to methyl mercury by the action of microorganisms. It enters the food chain - phytoplankton - zooplankton - small fish - big fish. At the top of this chain are animals (that feed on fish), including humans. Within this chain, the process of bioaccumulation of ethylmercury occurs. As reported by [11, 78], its concentration is gradually increasing, with the values at the top of the chain about a million times higher than the concentration of methylmercury in the surrounding water. In general, large and longer-living fish (shark, tuna, mackerel, pike) also contain more mercury [48, 79, 80]. Under "European Commission Decision 93/351", the value of Hg in the meat of fish living in relatively uncontaminated areas should be below 0.5 gg<sup>−</sup><sup>1</sup> .The concentration of mercury in the air ranges from 1 to 5 mg.m<sup>−</sup><sup>3</sup> in rural areas and 7–10 mg.m<sup>−</sup><sup>3</sup> in cities. The enrichment of soils with mercury is caused by the burning of coal, the occurrence of cinnabar deposits, but also by applying mercury-based fungicides. The use of sewage and urban sludge and fertilizers is also a source of mercury soil pollution. However, this is not just about soil contamination, but also about secondary effect on vegetation growing on it [81]. Mercury gets into the soil in the range of 0.02–03 mg.kg<sup>−</sup><sup>1</sup> . The concentration of mercury in uncontaminated soils should be within the range of 0.02–0.2 mg.kg<sup>−</sup><sup>1</sup> [82]. Average concentrations affected by human activity are in the range of 0.1–0.4 mg.kg<sup>−</sup><sup>1</sup> , and in the vicinity of industrial enterprises and crematoria up to 1.8 mg.kg<sup>−</sup><sup>1</sup> , in the third of Slovakia's territory the content of total mercury is higher in woody plants (the value exceeds 0.12 mg.kg<sup>−</sup><sup>1</sup> ) [11, 83, 84]. The natural content in the soil is from several, up to tens of μg.kg<sup>−</sup><sup>1</sup> . The use of mercury and its compounds has spread rapidly, and this fact cannot remain without consequences for: the environment, living organisms, including humans and animals. Therefore it is important to create favorable living conditions also for livestock (active health creation) based on the fundamental phenomena - complexity of measures and respect for the variability of the effects of relationships and factors between the internal and external environment [7]. **Effects of toxic action of mercury on the organism:** Regarding the effects of toxic effects on the organism, mercury is given a relatively high attention. Its toxicity depends on the physical properties of the individual forms. However, there are differences among them, based on the way of exposure, the metabolism itself, the way of excretion. It is known that the more mobile the form of mercury is, the more toxic it becomes. These properties are due to the structure of the molecule (e.g., behavior in biosystems, stability, excretion rates, etc.) [49, 85]. The negative impact not only on the health of people but also on the health and the performance of the animals results from an increased incidence of mercury, especially in polluted areas. The hygienic quality of animal products is lower, the content of toxic elements in meat and dairy

products is higher and the reproductive and growth indicators get reduced [9, 86]. Mercury is the world's only liquid metal that gets into the body most often by inhalation of mercury vapor, and up to 80% of these is absorbed in the lungs. The absorption of elemental mercury in the GIT is very low, less than 1%. [87] report that compounds containing divalent mercury are absorbed in GIT more, even up to 10%. Further, it is taken into consideration that oral administration may be accidental, or in contact with skin. As stated by [88], this metal has a high affinity for phosphates, cysteine and histidinyl side chains of proteins, but also for purines, porphyrins and pteridines. Mercury, along with its compounds, is one of the high-toxic poisons (5 times more toxic than lead). The harmful daily human dose is 0.4 mg, the lethal dose is 150–300 mg. The condition of its toxic effect is the oxidation of Hg0 to Hg1+ up to Hg2+. After oxidation, Hg2+ binds to -SH groups of proteins, which are thereby inactivated. Upon absorption, a large proportion of mercury (depending on the type of compound and the site of absorption) gets into circulation. A part enters the erythrocytes and another part binds to the ligands in the plasma. The ratio of mercury content in plasma and in erythrocytes is about 1: 1. In erythrocytes, mercury (Hg) binds to the -SH group of hemoglobin. Elemental mercury (e.g. in mercury vapor poisoning) is oxidized to divalent cation. In plasma, mercury binds to albumin and other plasma proteins that contain free -SH groups. Exposure to mercury increases the amount of metallothionein (low molecular weight protein), which to some extent prevents kidney damage [11, 89, 90]. Elemental mercury and some of its organic compounds easily cross membranes (e.g., the erythrocyte membrane) and, unlike some other heavy metals (e.g. cadmium), easily cross the placental blood–brain barrier, too. In the complex with glutathione it is excreted in the bile, but it also reaches the sweat, salivary and dairy glands. In humans, the mean half-life of excretion for inorganic mercury is 60 days, for alkyl compounds of mercury 70 days [73]. The kidneys are the site of the greatest accumulation of mercury and also the major site of its excretion. There are several hypotheses explaining the mechanism of mercury excretion in the kidneys. One of them is the hypothesis that part of it gets into the urine in binding to albumin and then is reabsorbed (by endocytosis) in the proximal tubule. Another part is excreted in binding to glutathione, which is, similar to bile, hydrolyzed to amino acids by γ-glutamyltransferase and dipeptidases, and such amino acids are then reabsorbed by the Na-dependent transport system [91]. Mercury is excreted in the feces and urine. For inorganic mercury, the excretion half-life (both acute and chronic) is 1–3 months, for methylmercury it is 50 days. Since methylmercury permeates the hair, the level is used as a marker of mercury exposure [11, 92]. Food that has been contaminated with methylmercury (especially fish) are among the most common sources of exposure to organic mercury. At the end of the 19th century, [93] described the so-called pink disease (acrodynia - sporadic and predominant pediatric syndrome associated with calomel in toothpaste and other forms of inorganic mercury) related to an allergic reaction in hypersensitive people. Abnormal reddening of the skin has occurred, as well as peeling of the skin (area of the hands, legs, feet), pain threshold reduction, swelling. Acrodynia has been found in infants but also in older children who have used diapers treated with phenylmercury (an organic form of mercury). In spite of the scientifically-based study, mercury is still a part of various cosmetics and pharmaceutical compositions. However, it should be noted that the skin reactions to mercury are relatively rare, even scarce. The concentration of mercury in the blood in the general population (the result of dietary intake) is mainly in the form of organic compounds, but it is present in the urine mainly in inorganic form. Why this is the case (difference in form) yet needs to be further explored in mammals. As reported by [94], mercury concentration in blood increases with fish consumption. However, larger areas of

**51**

**5. Conclusion**

VEGA 2/0125/17.

*Heavy Metals and the Environment*

*DOI: http://dx.doi.org/10.5772/intechopen.86876*

amalgam fillers, which may be the source of increased urinary excretion, also need to be considered. Other so-called immunotoxic responses can also be induced when exposed to inorganic mercury - Kawasaki disease, rash, cracking of the lips, fever, photophobia, pharyngitis, peeling of the skin on the palms of the hands and feet, tachycardia, affection of the lymphatic tissue - these are symptoms afflicted by sufferers. Urine levels of mercury have been shown to be higher in the affected patients. [93] reports that infants but also older children have more sensitive organisms than adults, and that explains the higher absorption of inorganic mercury. Among the organic mercury compounds, thiomersal (thimerosal, mertiolate, sodium ethylmercurithiosalicylate) is known as being used as a preservative in childhood vaccination since the 1930s. The thiomersal composition is 49.6 wt% Hg - it is metabolized to EtHg and thiosalicylate. The vaccine dose for children contains about 2.5 mg Hg in 0.5 ml. [95, 96] have expressed concern that the developing CNS could be harmed in children in the first half year of life. Possible health consequences: delayed speech development, impaired concentration, local hypersensitive responses, the spectrum of autism disorders. With long-term administration of gamma globulin (containing thiomersal), acrodynia has occasionally been confirmed. Based on these findings, thiomersal was requested to be removed from vaccines. However, it continues to be used in some countries to these days. According to [97] at high doses of EtHg the undesirable effects are similar to high doses of MeHg. However, the effect of low dose of EtHg remains unclear, more recent data [98] describe EtHg to be less neurotoxic than MeHg. The effects of mercury on health depend on several factors (form, dose, duration of exposure).

International organizations Health Care Without Harm and the Health &

compounds are, according to IARC, rated as possible carcinogens [63].

Population health, as a universal value and primary human rights, is a fundamental economic resource not only for the individual but also for the whole of society. One of the main starting points for solving the relationship between man and the environment is the planned nature protection. The environment is everything that creates natural conditions for the existence of organisms, including humans, and is a prerequisite for their further development. The work was supported by

Environment Alliance advocate accelerated reduction of environmental pollution by mercury in the European Union as well as worldwide and raise awareness of its destructive impact on the human fetal brain (arises during the early development of the fetus by methylmercury). It has a damaging effect on the development of the nervous system, and such damage is mostly irreversible. [99] states that the source of intense interest in the scientific community is primarily three chemical forms as a source of exposure: methyl mercury in fish, mercury vapor from amalgam dental fillings, and ethyl mercury in vaccines. US EPA (Environmental Protection Agency) classifies inorganic mercury into Group D "substances that do not have carcinogenic effects on humans" but [100] is considering reviewing the inclusion of inorganic mercury according to EPA. Organic forms of mercury - methyl mercury and its

#### *Heavy Metals and the Environment DOI: http://dx.doi.org/10.5772/intechopen.86876*

*Environmental Factors Affecting Human Health*

oxidation of Hg0

products is higher and the reproductive and growth indicators get reduced [9, 86]. Mercury is the world's only liquid metal that gets into the body most often by inhalation of mercury vapor, and up to 80% of these is absorbed in the lungs. The absorption of elemental mercury in the GIT is very low, less than 1%. [87] report that compounds containing divalent mercury are absorbed in GIT more, even up to 10%. Further, it is taken into consideration that oral administration may be accidental, or in contact with skin. As stated by [88], this metal has a high affinity for phosphates, cysteine and histidinyl side chains of proteins, but also for purines, porphyrins and pteridines. Mercury, along with its compounds, is one of the high-toxic poisons (5 times more toxic than lead). The harmful daily human dose is 0.4 mg, the lethal dose is 150–300 mg. The condition of its toxic effect is the