5.3 Health Hazards from Heavy Metal Pollution

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earth crust, is present in soil, air, and water as chemical compounds in both inorganic

and organic forms. Environmental arsenic pollution is increasing due to its mobiliza-

tion from geological sources and anthropological and industrial activities. One of the

major sources of As is its potential mobilization and transport in the ground water

and drinking water supplies. In India, West Bengal state is most affected from arsenic

contamination in ground water. An estimated 6 million people in West Bengal and

57 million people in Bangladesh have been exposed to arsenic through contami-

nated wells. Lead (Pb) has been introduced in the environment from a variety of

sources such as storage battery, lead smelting, tetraethyl-lead manufacturing and

mining, plating, ammunition, ceramic, and glass industries. It has been used in pip-

ing, building materials, solders, paint, type metal, ammunition, and castings since

the medieval times. Thus, human activities are a major cause of increase in the con-

centrations of these heavy metals in the soil. Scientific investigations demonstrated

that the concentration of heavy metals in several sites, assessed in water, soil, and

sediment samples, are affected by different anthropogenic pollution sources.

5.3

Health Hazards from Heavy Metal Pollution

Heavy metal affects health in myriad ways, which include heart disease, liver

damage, cardiovascular, neurological diseases, and cancer (Table 5.1). The

contamination of drinking water supplies is of particular concern; soils and

sediments are the major sinks for metals. Heavy metal contamination in soil can

accumulate in crop and therefore transferred and resulted in bioaccumulation.

Heavy metals are ever persistent in the earth and consequently are difficult to

remove from the environment. The chemical nature and bioavailability of a metal

can be changed through oxidation or reduction; however, the elemental nature

remains the same because the metals are neither thermally decomposable nor

degradable. Because of the toxicity and the ubiquity of the metals in environment,

microbes have evolved various unique adaptations to deal with high concentra-

tions of metals [1]. Microorganisms have been previously reported to sequester

Table 5.1

Health hazards caused by environmental heavy metal pollution.

Heavy metal

Health hazard(s)

Nickel (Ni)

Hypersensitivity; cancer; pulmonary cancer; nasal sinus cancer;

neurological disorders; abortion of pregnancy

Chromium (Cr)

Oral toxicity; respiratory problems (e.g. asthma); acute tubular

necrosis; kidney failure

Arsenic (As)

Blackfoot disease; skin, bladder, liver and lung cancers; arsenicosis

Lead (Pb)

Anemia; central nervous system and neuromuscular ailments; chronic

renal problems; abnormal sperm production

Cadmium (Cd)

Acute gastrointestinal effect; pneumonitis; kidney damage;

interference in progesterone and testosterone production;

osteoporosis; prostate cancer; renal cancer