written by: Mayflor Markusic•edited by: Niki Fears•updated: 8/15/2009
Heavy metals enter the environment through various natural processes and anthropogenic activities. These metal pollutants have toxic effects when ingested into the human body. What are these metals, their sources, and their possible effects?
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Anthropogenic activities contribute to the increase of toxic heavy metals in the environment. These metals enter the atmosphere and contribute to air pollution. Some of them reached the ground and carried off by runoffs, contributing to water pollution. Here is a list of metals that easily enter the environment and pose health hazards to the community.
Antimony (Sb) - It is used in various electrical applications, in expectorants, in manufacturing munitions, and in semiconductors. In low doses, antimony is relatively harmless, but large doses can cause poisoning, stomach ulcers, heart diseases. It is unfortunate that antimony is found in PET (polyethylene terephthalate) bottles and over time, this metal can leach out of the bottle.
Arsenic (As) -It is a component of animal feed, ceramics, pesticides, paints, and fireworks. The ingestion of about 70 mg of arsenic or arsenic compounds is considered lethal. Lower doses of arsenic, which is present in many polluted waters, can lead to various types of cancer, such as skin cancer, bladder cancer, and lung cancer.
Cadmium (Cd) - It is found in Ni-Cd batteries and part of various metallic alloys, pigments, and the anti-corrosion coatings of other metals. The cadmium dissolved in water is as toxic as the cadmium that is inhaled in the air. It is also bioaccumulated. Cadmiun interferes with the body's major metabolic processes and can also lead to cancer and teratogenesis.
Chromium (Cr) - It is essential in tanning leather, treating wood, storing data, making pigments, and in manufacturing iron-based alloys. The human body will need trace amounts of chromium III (Cr3+)in order to help metabolize fats and carbohydrates. But if the body ingests more or if the body is exposed to the more dangerous chromium VI (CR6+), it will most likely suffer from lung cancer, weak immune system, ulcer, and liver damage.
Cobalt (Co) - It is used manufacturing glasses and ceramics and in various metallurgical processes. It enters the air and then eventually settles down to the ground and contribute to water pollution. In small amounts, cobalt is extremely beneficial to the body because it is an essential part of vitamin B12. In large amounts, cobalt becomes dangerous to the lungs and heart. Overexposure to cobalt leads to vomiting, nausea, and coma or death.
Lead (Pb) - It is found in plastics, ceramics, glassware, pigments, and batteries. Lead is also a crucial component in anti-knock agents. But lead easily vaporizes and enter the atmosphere. Behavioral problems are the least worrisome effects of ingesting lead. This toxic heavy metal can cause severe anemia, brain damage and even death.
Mercury (Hg) - Known as quicksilver, this fascinating metal is in liquid state at room temperatures. It is a component in dental fillings, fungicides, solders, and various scientific instruments. When ingested, mercury damages the central nervous system leading to a group of diseases called neuropathy. Many victims of mercury poisoning are those who eat mercury-laden fish and those who are exposed to coal plants.
Nickel (Ni) - It is an important element in the steel industry. Nickel is used in making batteries, welding rods, adding pigments to paints, and producing dental and surgical prostheses. With nickel in practically everything that people use, exposure is unavoidable. Fortunately, there are no lethal effects due to minimal exposures. Overexposures, however, lead to lung cancer, asthma-like symptoms, and various organ problems.