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Lead

Biological Effects

Throughout most of human history, lead was used for a wide variety of applications with little or no appreciation of the serious health hazards it poses. Today, physiologists understand that the human body is able to excrete about 2 milligrams of lead efficiently each day, but that quantities in excess of that can cause serious health problems.

Children are especially at risk for lead poisoning. Their bodies do not metabolize lead as quickly as do those of adults, so a given concentration of lead in the blood will have more serious consequences for a child than for an adult.

At relatively low concentrations, lead produces relatively modest or short-term effects, including elevation of blood pressure, reduction in the synthesis of hemoglobin, and decreased ability to utilize vitamin D and calcium. With increased blood concentrations of lead, however, these problems become more severe. Impairment of the central nervous system can occur, with decreased mental functioning and hearing damage as two possible results. At very high lead concentrations, a person can fall into a coma and, eventually, die.

With the recognition of these problems, governmental agencies have continually restricted the number of applications in which lead can be used. Unfortunately, its widespread use in previous years means that many children (especially) and adults are still at risk for lead poisoning. As an example, children not uncommonly pick off and then eat chips of paint from the walls of old buildings. Since many of these paints were made with compounds of lead, those children are then exposed to the harmful effects of the element.

Resources

Books

Emsley, John. Nature's Building Blocks: An A-Z Guide to the Elements. Oxford: Oxford University Press, 2002.

Greenwood, N.N., and A. Earnshaw. Chemistry of the Elements. 2nd ed. Oxford: Butterworth-Heinneman Press, 1997.

Hawley, Gessner G., ed. The Condensed Chemical Dictionary. 9th edition. New York: Van Nostrand Reinhold 1977.

Joesten, Melvin D., David O. Johnston, John T. Netterville, and James L. Wood. World of Chemistry. Philadelphia: Saunders, 1991.

"Lead." Kirk-Othmer Encyclopedia of Chemical Technology. 4th ed. Suppl. New York: John Wiley & Sons, 1998.


David E. Newton

KEY TERMS

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Ductile

—Capable of being drawn or stretched into a thin wire.

Flux

—In the conversion of ores to metals, a substance used to remove impurities from a blast furnace or other kind of processing system.

Froth flotation

—A system for separating a desired ore from other kinds of ores by pumping air through a mixture of water and one or more other substances.

Hemoglobin

—An iron-containing, protein complex carried in red blood cells that binds oxygen for transport to other areas of the body.

Isotopes

—Two molecules in which the number of atoms and the types of atoms are identical, but their arrangement in space is different, resulting in different chemical and physical properties.

Additional topics

Science EncyclopediaScience & Philosophy: Laser - Background And History to Linear equationLead - General Properties, Where It Comes From, How The Metal Is Obtained, How We Use It