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Poisons and Toxins


It is critical to understand that while any chemical can cause poisoning, a threshold of tolerable dose must be exceeded for this to actually happen. The great challenge of toxicology is to provide society with a clearer understanding of the exposures to potentially toxic chemicals that can be tolerated by humans, other species, and ecosystems before unacceptable damages are caused. Many naturally occurring and synthetic chemicals can be used for diverse, useful purposes, but it is important that we understand the potentially toxic consequences of increasing exposures to these substances.

See also Bioaccumulation.



Freedman, B. Environmental Ecology. 2nd ed. San Diego: Academic Press, 1995.

Klaassen, Curtis D. Casarett and Doull's Toxicology. 6th ed. Columbus: McGraw-Hill, Inc., 2001.

Smith, R.P. A Primer of Environmental Toxicology. Philadelphia: Lea & Febiger, 1992.


"Better Killing Through Chemistry." Scientific American (December 2001).

Bill Freedman


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Acute toxicity

—A poisonous effect produced by a single, short-term exposure to a toxic chemical, resulting in obvious tissue damage, and even death of the organism.


—This is an estimate of the concentration or effect of a potentially toxic chemical, measured using a biological response under standardized conditions.

Chronic toxicity

—This is a poisonous effect that is produced by a long period of exposure to a moderate, sub-acute dose of some toxic chemical. Chronic toxicity may result in anatomical damages or disease, but it is not generally the direct cause of death of the organism.


—In toxicology, exposure refers to the concentration of a chemical in the environment, or to the accumulated dose that an organism encounters.

Hidden injury

—This refers to physiological damages, such as changes in enzyme or other biochemical functions, that occur after exposure to a dose of a poison that is not sufficient to cause acute injuries.


—In toxicology, response refers to effects on physiology or organisms that are caused by exposure to one or more poisons.

Additional topics

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