O.K. The LD50. Animal Testing has been going on for OVER 30 yrs. NO? The LD50 The LD50 is a standardized measure for expressing and comparing the toxicity of chemicals. The LD50 is the dose that kills half (50%) of the animals tested (LD = lethal dose). The animals are usually rats or mice, although rabbits, guinea pigs, hamsters, and so on are sometimes used. Because a single test may kill as many as 100 animals, the United States and other members of the Organization for Economic Cooperation and Development agreed in December 2000 to phase out the LD50 test in favor of alternatives that greatly reduce (or even eliminate) deaths of the test animals. In all these tests, the dose must be calculated relative to the size of the animal. The most common units are milligrams of chemical per kilogram of test animal (mg/kg or ppm). Chemical Category Oral LD50 in Rats (mg/kg) Aldicarb (Temik) Carbamate 1 Carbaryl (Sevin) Carbamate 307 DDT Chlorinated hydrocarbon 87 Dieldrin Chlorinated hydrocarbon 40 Diflubenzuron (Dimilin) Chitin inhibitor 10,000 Malathion Organophosphate 885 Methoprene JH mimic 34,600 Methoxychlor Chlorinated hydrocarbon 5,000 Parathion Organophosphate 3 Piperonyl butoxide Synergist 7,500 Pyrethrins Plant extract 200 Rotenone Plant extract 60 The table gives the LD50 values for some insecticides. In each case, the chemical was fed to laboratory rats. Note that the lower the LD50, the more toxic the chemical. Even adjusting for the test animals weight, the LD50 for one species is often quite different from that for another. Thus any LD50 value gives only a rough estimate of the risk to humans. The way in which the chemical is administered also has a marked effect on LD50 values. The chemical may be fed, injected, applied to the animals skin, etc., and each method usually generates a different LD50.
Posted on: Tue, 08 Jul 2014 00:07:52 +0000
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