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What should I understand about chemicals and toxicity while using TOXMAP?

The effect a chemical has on a living organism-- if any-- is called the organism's response. The response is related to the chemical dose and to the resulting concentration of the chemical in the organism. (The dose is the total amount of chemical administered to, or taken by, an organism.) The dose of a chemical often determines the extent of the effect it produces. Understanding the dose-response relationship is necessary for understanding the cause and effect relationship between chemical exposure and illness.

The toxicity of a substance depends on many factors: the form and chemical activity; the dosage, especially the dose-time relationship; exposure route; species; age; sex; ability of the chemical to be absorbed; metabolism; distribution within the body; excretion; and the presence of other chemicals.

The variety of responses among organisms that get the same dose of chemical is due to individual susceptibility. Dose and individual susceptibility play roles in all situations involving chemical exposure. Toxicologists study responses of living organisms to doses of chemicals.

Always keep in mind that the co-occurrence of a substance and a particular health problem does not by itself imply an effect on human health by that substance; the association of two or more variables (correlation) does not, by itself, imply a cause and effect relationship.

You can learn more about chemicals and toxicity with these Toxicology Tutorials (http://sis.nlm.nih.gov/enviro/toxtutor.html). These three short high school level tutorials about basic toxicology are organized by chapter and offer text, graphics, and quizzes/assessments.