**1. Introduction**

Environmental pollution by toxic metals occurs globally through military, industrial, and agricultural processes and waste disposal (Duffus, 2002). Fuel and power industries generate 2.4 million tons of As, Cd, Cr, Cu, Hg, Ni, Pb, Se, V, and Zn annually The metal industry adds 0.39 million tons/yr of the same metals to the environment, while agriculture contributes 1.4 million tons/yr, manufacturing contributes 0.24 million tons/yr and waste disposal adds 0.72 million tons/yr. Metals, discharged or transported into the environment, may undergo transformations and can have a large environmental, public health, and economic impact (Brower et al. 1997; Nriagu & Pacyna, 1988; Gadd & White, 1993).

Among different techniques used for removal of high concentrations of heavy metals, precipitation-filtration, ion exchange, reverse osmosis, oxidation-reduction, solvent extraction, as well as membrane separation should be mentioned (Hubicki,et al. 1999; Dąbrowski et al. 2004). However, some of the wastes contain substances such as organics, complexing agents and alkaline earth metals that may decrease the metal removal and result in unacceptable concentrations of heavy metals in the effluents. The pollutants of concern include cadmium, lead, mercury, chromium, arsenic, zinc, cobalt and nickel as well as copper. They have a number of applications in basic engineering works, paper and pulp industries, leather tanning, petrochemicals, fertilizers, etc. Moreover, they have also negative impact on human health.

**Cadmium** is a metal of great toxicological concern. An important source of human exposure to cadmium is food and water, especially for the population living in the vicinity of industrial plants, from which cadmium is emitted to the air. In the case of exposure to occupational cadmium compounds, they are absorbed mainly by inhalation. Through the

© 2012 Hubicki and Kołodyńska, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Hubicki and Kołodyńska, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

gastrointestinal tract less than 10% cadmium is absorbed. An important source of human exposure to cadmium is food and water. In natural water its typical concentration lies below 0.001 mg/dm3, whereas, the upper limit recommended by EPA (Environmental Protection Agency) is less than 0.003 mg/dm3. The maximum limit in drinking water is 0.003 mg/dm3.

Cadmium accumulates in kidneys, pancreas, intestines and glands altering the metabolism of the elements necessary for the body, such as zinc, copper, iron, magnesium, calcium and selenium. Damage to the respiratory tract and kidneys are the main adverse effects in humans exposed to cadmium compounds. In humans exposed to fumes and dusts chronic toxicity of cadmium compounds is usually found after a few years. The main symptom of emphysema is that it often develops without preceding bronchitis. The second basic symptom of chronic metal poisoning is kidney damage. It includes the loss and impairment of smell, pathological changes in the skeletal system (osteoporosis with spontaneous fractures and bone fractures), pain in the extremities and the spine, difficulty in walking, the formation of hypochromic anemia. The most known 'Itai-Itai' disease caused by cadmium exposure is mixed osteomalacia and osteoporosis. However, an important source of cadmium in soils are phosphate fertilizers. Large amounts of cadmium are also introduced to soil together with municipal waste. The high mobility of cadmium in all types of soils is the reason for its rapid integration into the food chain. Daily intake of cadmium from food in most countries of the world is 10-20 mg.

**Lead** is a toxic metal, which accumulates in the vital organs of men and animals and enters into the body through air, water and food. According to the WHO (World Health Organization) standards, its maximum limit in drinking water is 0.05 mg/dm3 but the maximum discharge limit for lead in wastewater is 0.5 mg/dm3. Its cumulative poisoning effects are serious haematological damage, anaemia, kidney malfunctioning, brain damage etc. Chronic exposure to lead causes severe lesions in kidney, liver, lungs and spleen.

Lead is used as industrial raw material in the manufacture of storage batteries, pigments, leaded glass, fuels, photographic materials, matches and explosives. Lead being one of very important pollutants comes from wastewaters from refinery, wastewaters from production of basic compounds containing lead, wastewaters with the remains of after production solvents and paints. Large toxicity of lead requires that its contents are reduced to the minimum (ppb level). To this end there are applied chelating ions with the functional phosphonic and aminophosphonic groups. Also weakly basic anion exchangers in the free base form can be used for selective removal of lead(II) chloride complexes from the solutions of pH in the range 4-6. Also a combined process of cation exchange and precipitation is often applied for lead(II) removal form wastewaters (Pramanik et al. 2009). The average collection of lead by an adult was estimated at 320-440 mg/day. Acute poisoning with inorganic lead compounds occurs rarely. In the case of acute poisoning in man, the symptoms are burning in the mouth, vomiting, abdominal cramps, diarrhea, constipation progressing to systolic, blood pressure and body temperature. At the same time there is hematuria, proteinuria, oliguria, central nervous system damage. Alkyl lead compounds are more toxic than inorganic lead connections. Tetraethyl lead toxicity manifested primarily in lead damage of the nervous system. Toxic effects of lead on the central nervous system are observed more in children. In adults, the effects of lead toxicity occur in the peripheral nervous system. Symptoms of chronic poisoning may vary. The acute form of poisoning known as lead colic is the general state of various spastic internal organs and neurological damage in the peripheral organs. Long-term lead poisoning can lead to organic changes in the central and peripheral nervous systems. Characteristic symptoms include pale gray skin colour and the lead line on the gums (blue-black border).

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in most countries of the world is 10-20 mg.

gastrointestinal tract less than 10% cadmium is absorbed. An important source of human exposure to cadmium is food and water. In natural water its typical concentration lies below 0.001 mg/dm3, whereas, the upper limit recommended by EPA (Environmental Protection Agency) is less than 0.003 mg/dm3. The maximum limit in drinking water is 0.003 mg/dm3.

Cadmium accumulates in kidneys, pancreas, intestines and glands altering the metabolism of the elements necessary for the body, such as zinc, copper, iron, magnesium, calcium and selenium. Damage to the respiratory tract and kidneys are the main adverse effects in humans exposed to cadmium compounds. In humans exposed to fumes and dusts chronic toxicity of cadmium compounds is usually found after a few years. The main symptom of emphysema is that it often develops without preceding bronchitis. The second basic symptom of chronic metal poisoning is kidney damage. It includes the loss and impairment of smell, pathological changes in the skeletal system (osteoporosis with spontaneous fractures and bone fractures), pain in the extremities and the spine, difficulty in walking, the formation of hypochromic anemia. The most known 'Itai-Itai' disease caused by cadmium exposure is mixed osteomalacia and osteoporosis. However, an important source of cadmium in soils are phosphate fertilizers. Large amounts of cadmium are also introduced to soil together with municipal waste. The high mobility of cadmium in all types of soils is the reason for its rapid integration into the food chain. Daily intake of cadmium from food

**Lead** is a toxic metal, which accumulates in the vital organs of men and animals and enters into the body through air, water and food. According to the WHO (World Health Organization) standards, its maximum limit in drinking water is 0.05 mg/dm3 but the maximum discharge limit for lead in wastewater is 0.5 mg/dm3. Its cumulative poisoning effects are serious haematological damage, anaemia, kidney malfunctioning, brain damage

Lead is used as industrial raw material in the manufacture of storage batteries, pigments, leaded glass, fuels, photographic materials, matches and explosives. Lead being one of very important pollutants comes from wastewaters from refinery, wastewaters from production of basic compounds containing lead, wastewaters with the remains of after production solvents and paints. Large toxicity of lead requires that its contents are reduced to the minimum (ppb level). To this end there are applied chelating ions with the functional phosphonic and aminophosphonic groups. Also weakly basic anion exchangers in the free base form can be used for selective removal of lead(II) chloride complexes from the solutions of pH in the range 4-6. Also a combined process of cation exchange and precipitation is often applied for lead(II) removal form wastewaters (Pramanik et al. 2009). The average collection of lead by an adult was estimated at 320-440 mg/day. Acute poisoning with inorganic lead compounds occurs rarely. In the case of acute poisoning in man, the symptoms are burning in the mouth, vomiting, abdominal cramps, diarrhea, constipation progressing to systolic, blood pressure and body temperature. At the same time there is hematuria, proteinuria, oliguria, central nervous system damage. Alkyl lead compounds are more toxic than inorganic lead connections. Tetraethyl lead toxicity

etc. Chronic exposure to lead causes severe lesions in kidney, liver, lungs and spleen.

In nature, natural circulation of **mercury** vapour has a significant influence on the content of the soil and water. Elemental mercury in the rain water creates compounds by oxidation to divalent mercury. Both the chemical reaction, and under the influence of biological factors, and especially the activity of bacteria in the sediments of water bodies methyl and dimethyl mercury compounds are formed. Mercury, a fixed component of the waste water treatment that may be used for soil fertilization is a major threat to the inclusion of the metal in nutritional products. Drinking water may contain up to 300 ng Hg/dm3, in highly industrialized areas it can reach up to 700 ng/dm3. Daily consumption of mercury from food in the general population is less than 20 g/day. 80% of mercury absorbed by the respiratory system is retained in the body. In the case of ingestion of inorganic mercury salts, salivation, burning in the throat, vomiting, bloody diarrhea, necrosis of the intestinal mucosa and kidney damage, leading to anuria and uremii can occur. The concentration of mercury vapour over 1 mg/m3 damages lung tissue and causes severe pneumonia. The classic symptoms of metallic mercury vapour poisoning are manifested by tremor, mental disorders, inflammation of the gums. Its maximum limit in drinking water is 0.0005 mg/dm3.

**Chromium**, occurring as Cr(III) or Cr(VI) in natural environments, is an important material resource, an essential micronutrient or toxic contaminant. Cr(III) is required for normal development of human and animal organisms but Cr(VI) activates teratogenic processes, disturbs DNA synthesis and can give rise to mutagenous changes leading to malignant tumours (WHO, Report 1998). Natural sources of chromium include weathered rocks, volcanic exhalations and biogeochemical processes and, in the man-polluted environment, mainly wastes after processing and utilization of chromium compounds. Chromium is an important and widely applied element in industry. The hexavalent and trivalent chromium is often present in electroplating wastewater. Other sources of chromium pollution are leather tanning, textile, metal processing, paint and pigments, dyeing and steel fabrication. To remove toxic chromium compounds from sewages there are used such methods as: precipitation, coagulation, solvent extraction and various kinds of membrane processes, ion flotation, adsorption and ion exchange (Bajda, 2005). The maximum limit in drinking water is 0.05 mg/dm3. The Polish drinking groundwater chromium content ranges on the average from 0.07 to 2 mg/dm3. 0.02 mg/dm3 is accepted as the permissible content of chromium in groundwater. The daily dose taken by the adult can be 50-200 mg/day (or 60-290 mg/day). Cr(III) cation predominates in most tissues except the liver. Chromium is associated with nucleic acids and is the subject to the concentration in liver cells. It plays an important role in the metabolism of glucose, certain proteins and fats, is part of enzymes and stimulates the activity of others. All compounds of chromium, with the exception of chromate, are rapidly cleared from the blood. Chromium also accumulates in the liver and kidneys. High concentrations of chromium, observed in the lungs of people exposed to this metal, indicate that at least part of chromium is stored in this organ in the form of insoluble compounds. The binding of chromium with the elements of the blood and transport of chromium by the blood depends mainly on its valence. Hexavalent chromium readily crosses the membranes of red blood cells and after reduction to trivalent chromium is bound to hemoglobin. The reduction of hexavalent to trivalent chromium, occurring within cells, considered as the activation of the carcinogenic chromium, increases because the probability of interaction of trivalent chromium on the DNA. Clinical signs of acute toxicity of chromium compounds are characterized by severe abdominal pain, vomiting and bloody diarrhea, severe kidney damage with hematuria leading to anuria, observed gastrointestinal ulceration. Chromium compounds and chromic acid are especially dangerous and cause serious damage to internal organs. Chronic exposure leads to chronic disorders in the body.

**Arsenic** is present in over 160 minerals. It is readily bioaccumulative and therefore its concentration in polluted waters may reach 430 mg/dm3 in plants and 2.5 mg/dm3 in fish**.**  The upper limit of arsenic recommended by US EPA, EU and WHO is 0.01 mg/dm3. However, many countries have retained the earlier WHO guideline of 0.05 mg/dm3 as their standard.

Arsenic accumulates in tissues rich in keratin, like hair, nails and skin. Arsenic and its inorganic compounds can cause not only cancer of the respiratory system and skin, but also neoplastic lesions in other organs. Arsenic compounds enter the body from the gastrointestinal tract and through skin and respiratory system. Arsenic compounds have affinity for many enzymes and can block their action, and above all disturb the Krebs cycle. Inorganic arsenic compounds are more harmful than organic and among them AsH3 and As2O3 should be mentioned. 70-300 mg of As2O3 is considered to be the average lethal dose for humans. The dose of 10-50 ppb for 1 kg of body weight can cause circulatory problems, resulting in necrosis and gangrene of limbs. The dominant effects of arsenic in humans are changes in the skin and mucous membranes as well as peripheral nerve damage. There are xerosis soles and palms, skin inflammation with ulceration. In addition, there is perforation of the nasal septum. The values of the maximum allowable concentration (NDS) in Poland set for inorganic arsenic compounds are 0.3 mg/m3 and 0.2 mg/m3 for AsH3.

In nature, **zinc** occurs in the form of minerals. An important source of zinc pollution is the burning of coal, petroleum and its products. Incineration of municipal solid waste can introduce about 75% zinc to urban air. Also, municipal wastewater generally contains significant amounts of zinc. The use of municipal and industrial waste in agriculture results in the accumulation of zinc in the surface layers of soil. Another source of this metal in soils are some preparations of plant protection products, as well as phosphatic fertilizers. The degree of toxicity of zinc is not big, but it depends on the ionic form, and changes under the influence of water hardness and pH. The daily average download of zinc by an adult is estimated at about 10-50 mg /day. The toxic dose is 150-600 mg. It is necessary for the proper functioning of living organisms and it is involved in the metabolism of proteins and carbohydrates. High doses of zinc cause damage to many biochemical processes followed by its deposition in the kidneys, liver, gonads. Kidney play an important role in maintaining zinc homeostasis in the body. Zinc is relatively non-toxic to humans and animals. Hazard zinc mainly connected with secondary copper deficiency does not give specific symptoms.

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standard.

cleared from the blood. Chromium also accumulates in the liver and kidneys. High concentrations of chromium, observed in the lungs of people exposed to this metal, indicate that at least part of chromium is stored in this organ in the form of insoluble compounds. The binding of chromium with the elements of the blood and transport of chromium by the blood depends mainly on its valence. Hexavalent chromium readily crosses the membranes of red blood cells and after reduction to trivalent chromium is bound to hemoglobin. The reduction of hexavalent to trivalent chromium, occurring within cells, considered as the activation of the carcinogenic chromium, increases because the probability of interaction of trivalent chromium on the DNA. Clinical signs of acute toxicity of chromium compounds are characterized by severe abdominal pain, vomiting and bloody diarrhea, severe kidney damage with hematuria leading to anuria, observed gastrointestinal ulceration. Chromium compounds and chromic acid are especially dangerous and cause serious damage to internal

**Arsenic** is present in over 160 minerals. It is readily bioaccumulative and therefore its concentration in polluted waters may reach 430 mg/dm3 in plants and 2.5 mg/dm3 in fish**.**  The upper limit of arsenic recommended by US EPA, EU and WHO is 0.01 mg/dm3. However, many countries have retained the earlier WHO guideline of 0.05 mg/dm3 as their

Arsenic accumulates in tissues rich in keratin, like hair, nails and skin. Arsenic and its inorganic compounds can cause not only cancer of the respiratory system and skin, but also neoplastic lesions in other organs. Arsenic compounds enter the body from the gastrointestinal tract and through skin and respiratory system. Arsenic compounds have affinity for many enzymes and can block their action, and above all disturb the Krebs cycle. Inorganic arsenic compounds are more harmful than organic and among them AsH3 and As2O3 should be mentioned. 70-300 mg of As2O3 is considered to be the average lethal dose for humans. The dose of 10-50 ppb for 1 kg of body weight can cause circulatory problems, resulting in necrosis and gangrene of limbs. The dominant effects of arsenic in humans are changes in the skin and mucous membranes as well as peripheral nerve damage. There are xerosis soles and palms, skin inflammation with ulceration. In addition, there is perforation of the nasal septum. The values of the maximum allowable concentration (NDS) in Poland

In nature, **zinc** occurs in the form of minerals. An important source of zinc pollution is the burning of coal, petroleum and its products. Incineration of municipal solid waste can introduce about 75% zinc to urban air. Also, municipal wastewater generally contains significant amounts of zinc. The use of municipal and industrial waste in agriculture results in the accumulation of zinc in the surface layers of soil. Another source of this metal in soils are some preparations of plant protection products, as well as phosphatic fertilizers. The degree of toxicity of zinc is not big, but it depends on the ionic form, and changes under the influence of water hardness and pH. The daily average download of zinc by an adult is estimated at about 10-50 mg /day. The toxic dose is 150-600 mg. It is necessary for the proper functioning of living organisms and it is involved in the metabolism of proteins and carbohydrates. High doses of zinc cause damage to many biochemical processes followed by

set for inorganic arsenic compounds are 0.3 mg/m3 and 0.2 mg/m3 for AsH3.

organs. Chronic exposure leads to chronic disorders in the body.

**Nickel** is a moderately toxic element as compared to other transition metals. It is a natural element of the earth's crust; therefore its small amounts are found in food, water, soil, and air. Nickel occurs naturally in the environment at low levels. Nickel concentrations in the groundwater depend on the soil used, pH, and depth of sampling. The average concentration in the groundwater in the Netherlands ranges from 7.9 μg/dm3 (urban areas) to 16.6 μg/dm3 (rural areas). Acid rain increases the mobility of nickel in the soil and thus might increase nickel concentrations in the groundwater. In the groundwater with a pH below 6.2, nickel concentrations up to 0.98 mg/dm3 have been measured, whereas the upper limit recommended by FAO (Food & Agricultural Organization of the United Nation) for nickel in water is 0.02 mg/dm3. According to the Polish standards the maximum discharge limit for nickel in waste water is 2-3 mg/dm3. The maximum limit in drinking water in Europe is 0.01 mg/dm3. Although it has been suggested that nickel may be essential to plants and some animal species as well as in human nutrition, this metal causes damage to humans. Nickel occurs in seams of coal in the amount of 4-60 mg/kg. Crude oil contains about 50-350 mg/kg of the metal. The most dangerous is tetracarbonyl nickel occurring mostly in nickel refineries. The content of this metal in industrial and municipal wastewater ranges 20-3924 mg/kg. An important source of nickel pollution is its emissions to the air, the combustion of coal and liquid fuels, primarily by diesel engines. It is assumed that the concentration of nickel in the waters of the rivers should be about 1 g/dm3, while in most rivers of Europe it is as high as 75 g/dm3. Large amounts of nickel are given to surface waters from municipal wastewater in which the concentration exceeds 3000 ppm s.m. The permissible concentration should be 20 g/dm3. Nickel readily accumulatives particularly in phytoplankton or other aquatic plants. The daily absorption of nickel by humans ranges 0.3- 0.5 mg. In humans, the absorption of nickel from the gastrointestinal tract is less than 10%. Nickel taken with food and water is poorly absorbed and rapidly excreted from the body. It accumulates mainly in bones, heart, skin and various glands. Nickel inhalation of atmospheric air is largely accumulated in the lungs. Practically fatal or acute poisoning with nickel or its salts is not found. The most toxic compound is carbonyl nickel. An excess of inhaled nickel causes damage to the mucous membranes. Moreover, its symptoms are allergic disorders (protein metabolism disorder in plasma, changes in the chromosomes and changes in bone marrow and cancer. It is known that inhalation of nickel and its compounds can lead to serious problems, including, among others, respiratory system cancer. Moreover, nickel can cause skin disorder which is a common occupational disease in workers who handle its large amounts. Also dermatitis is the most common effect of chronic dermal exposure to nickel. Chronic inhalation exposure to nickel in humans also results in detrimental respiratory effects.

**Copper** is generally found in the earth's crust, usually in the form of sulphides. Municipal and industrial waste waters are an important source of pollution of rivers and water reservoirs. Copper accumulating plants may be the cause of poisoning. Copper is present in all types of water, and its content is subject to large variations (Barceloux, 1999). The natural content of copper in the river water ranges 0.9-20 g/dm3 and for saline waters 0.02-0.3 g/dm3. Copper is an essential nutritional element being a vital part of several enzymes. It is one of the components of human blood. The estimated adult dietary intakes are between 2 and 4 mg/day. The demand for copper is increased in pregnant women, children and the elderly. Good dietary sources of copper include animal liver, shellfish, dried fruit, nuts and chocolate. In some cases drinking water may also provide significant levels of copper. Copper in the body is involved in oxidation-reduction processes, acts as a stimulant on the amount and activity of hemoglobin, in the process of hardening of collagen, hair keratinization, melanin synthesis as well as affects on lipid metabolism and properties of the myelin sheath of nerve fibers. In animal cells it is mainly concentrated in the mitochondria, DNA, RNA, and the nucleus. Copper readily forms a connection with various proteins, especially those of sulphur. Although copper is an essential metal, it can, in some circumstances, lead to toxic effects including liver damage and gastrointestinal disturbances. Such as Wilson's disease (also known as hepatolenticular degeneration), Indian Childhood Cirrhosis (ICC) which are characterised by an accumulation of copper-containing granules within liver cells. Ingestion of high levels of copper salts is known to cause gastrointestinal upsets. Additionally, absorption of copper compounds by inhalation causes congestion of the nasal mucosa, gastritis, diarrhea and toxic symptoms such as chronic lung damage. Copper compounds act on the intact skin, causing it to itch and inflammation. They can cause conjunctivitis, ulceration and corneal opacity, nasal congestion and as well as sore throat and nasal septum. The upper limit recommended by WHO for copper is less than 1.3 mg/dm3. The maximum limit in drinking water is 0.05 mg/dm3 (Fewtrell et al. 1996).
