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Old June 7th, 2001, 09:31 PM   #34
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Acute Toxicity Tests

Acute toxicity tests, commonly called lethal dose or poisoning tests, determine the amount of a substance that will kill a percentage, even up to 100 percent, of a group of test animals.

In these tests, a substance is forced by tube into the animals' stomachs or through holes cut into their throats. It may also be injected under the skin, into a vein, or into the lining of the abdomen; mixed into lab chow; inhaled through a gas mask; or introduced into the eyes, rectum, or vagina. Experimenters observe the animals' reactions, which can include convulsions, labored breathing, diarrhea, constipation, emaciation, skin eruptions, abnormal posture, and bleeding from the eyes, nose, or mouth.<font color=red>(1)</font>

The widely used lethal dose 50 (LD50) test was developed in 1927. The LD50 testing period continues until at least 50 percent of the animals die, usually in two to four weeks.

Like eye irritancy tests, lethal dose tests are unreliable at best. Says Microbiological Associates' Rodger D. Curren, researchers looking for non-animal alternatives must prove that these in vitro models perform "at least as well as animal tests. But as we conduct these validation exercises, it's become more apparent that the animal tests themselves are highly variable."<font color=red>(2)</font> The European Center for the Validation of Alternative Methods' Dr. Michael Ball puts it more strongly: "The scientific basis" for animal safety tests is "weak."<font color=red>(3)</font>

<font size="2">1.Rowan, A.N. Of Mice, Models, & Men: A Critical Evaluation of Animal Research (Albany: State University of New York Press, 1984).
2. Branna, Tom, "Animal Testing Alternatives: Moving Closer to Validation?" happi, February 1995.
3. Ibid. </font>

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