Dr. Eva Schlede's paper discusses the issue of humane endpoints as a method of refinement in acute oral toxicity, skin and eye irritation and corrosion and skin sensitization studies. The method of utilizing specific clinical signs in the determination of humane endpoints and progress in the development of alternative methods is discussed.
Schlede's approach to the determination of humane endpoints in acute oral toxicity testing was to examine the results of numerous tests performed in various laboratories. It was found that there was a large variation in clinical signs documented by laboratories, as well as an enormous number of combinations of clinical signs observed. However, clinical signs shared by animals that died during the testing were determined to be "alert signs" for impending death. Schlede reported that there were no obvious single signs that might alert the toxicologist to proceed with euthanasia.
Schlede also addresses the refinements and reduction in skin and eye irritancy corrosion testing that have been used over the past 15 years. As determined by OECD guidelines, the required number of animals used per test has decreased from 6 animals to 3. Further refinement permits the use of a single animal. This reduction in number of animals used is the outcome of the comparison of chemicals based on properties and results of in vitro tests. Furthermore, animal use should not be required for skin sensitization tests if the chemical to be tested shares properties with a chemical that has already been categorized as a skin sensitizer.
Schlede concludes that refinements into toxicity testing can be made while also meeting human safety standards. To view Dr. Eva Schlede's paper, "Humane Endpoints in Toxicity Testing," download the full PDF.
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