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.
In radiology, the threshold dose is the smallest dose of radiation that will produce a specified effect. In the larger context of toxic exposure, threshold dose refers to the dose below which no harm is done. There is a threshold below which relatively little damage occurs from exposure, and above which the damage increases dramatically. For noncarcinogenic toxins, there does seem to be a safe dose for some substances, a threshold dose below which no harm is done. With carcinogens, however, just one change in the genetic materials of one cell may be enough to cause a malignant transformation that can lead eventually to cancer. Although there is some evidence that repair mechanisms or surveillance by the immune system may reduce the incidence of some cancers, it is generally considered prudent to assume that no safe or threshold dose exists for carcinogens.