The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
Persistent organic pollutants (POPs) are a subset of the more comprehensive term persistent bioaccumulative and toxic chemicals (PBTs). POPs commonly stands for organic (carbon-based) chemical compounds and mixtures that share four characteristics. They are semivolatile, stable under environmental conditions (half-lives of years to decades), fat-soluble, and possess the potential for adverse effects in organisms. Many POPs are organochlorine compounds. Among the twelve priority POPs defined by the United Nations Environmental Programme (and referred to as the "dirty dozen") are the pesticides aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex, and toxaphene (chlorobornanes); the industrial chemicals polychlorinated biphenyls (PCBs) and hexachlorobenzene; and the unintentional by-products dioxins and furans.
POPs' resistance to chemical and biological degradation and their propensity to evaporate led to their global distribution. By a constant process of deposition and reevaporation, POPs are transported by air and water currents to regions far from their sources until they ultimately gather in colder climates. Because of their lipophilicity, many POPs concentrate in organisms and accumulate to high levels in the top members of the food web such as predatory fish and birds, mammals and humans. Certain chemicals possess the ability to cross the placenta, while others are retained. Several contaminants present in the mother's body are thus handed down to the developing embryo in the womb—they are transferred to offspring across the placenta and through mother's milk. Adverse effects include cancer, endocrine disruption, reproductive dysfunction, behavioral abnormalities, birth defects, and interference with the immune and nervous systems.
Harrad, Stuart, ed. (2001). Persistent Organic Pollutants: Environmental Behaviour and Pathways of Human Exposure. Boston, MA: Kluwer.
United Nations Environmental Programme. "Persistent Organic Pollutants." Available from http://irptc.unep.ch/pops.