Updated and edited on May 20, 2016 by米歇尔A. Rivera.，About.com动物权利专家
LD50 value for a substance will vary according to the species involved. The substance may be administered any number of ways, including orally, topically, intravenously, or through inhalation. The most commonly used species for these tests are rats, mice, rabbits, and guinea pigs. Substances tested might include household products, drugs or pesticides. These particular animals are popular with animal testing facilities because they are not protected by the Animal Welfare Act which states, in part:
The LD50 test is controversial because the results have limited, if any, significance when applied to humans. Determining the amount of a substance that will kill a mouse has little value to human beings. Also controversial is the number of animals frequently involved in an LD50 trial, which may be 100 or more animals. Organizations such as the制药商协会,美国环境保护局，而且Consumer Product Safety Commission,among others, have all spoken out publicly against the use of too many animals in order to reach that 50 percent number. Approximately 60-200 animals are used even though the above organizations have indicated that these same tests could be successfully concluded by using only six to ten animals. The tests involved testing for “,,,toxicity of gases and powders (the inhalation LD50), irritancy and internal poisoning due to skin exposure (the dermal LD50), and toxicity of substances injected directly into animal tissue or body cavities (the injectable LD50),” according to the新英格兰反vivisection协会，其使命是结束动物测试和支持在活体动物上测试的替代品。所使用的动物are almost never given anesthesia and suffer tremendous pain during these tests.
由于公众侵害和科学进展，LD50测试已经主要被替代测试措施所取代。在“动物测试的替代方案中（环境科学和技术问题）”一些贡献者*讨论世界各地的实验室采用的替代方案，包括急性有毒类方法，上下和固定剂量程序。According to the National Institute of Heath，消费者产品安全委员会“强烈地阻止”使用LD50测试，而环保局则阻止其使用，也许是最不协调的食品和药物管理局不需要LD50测试以进行化妆品测试。
Merchants have used the public outcry to their advantage. Some have added the words “cruelty free” or some other indication that the company does not use animal testing on their finished product. But beware of these claims because there is no legal definition for these labels. So the manufacturer may not test on animals, but it’s entirely possible that the manufacturers of the ingredients which comprise the product are tested on animals.
International trade has also added to the confusion. While many companies have learned to avoid testing on animals as a public relations measure, the more the United States opens trades with other countries, the higher the chance that animal testing will again be part of the manufacture of a product previously deemed "cruelty free." For example, Avon, one of the first companies to speak out against animal testing, has begun selling their products to China. China requires some animal testing be done on certain products before being offered to the public. Avon chooses, of course, to sell to China rather than stand on ceremony and stick to their cruelty-free guns. And while these tests may or may not involve LD-50, the fact is that all the laws and regulations that have been so hard fought and won by animal-rights activists over the years won't mean a thing in a world where global trade is the norm.
If you want to live a cruelty-free life and enjoy following a vegan lifestyle, you have to be part detective and research the products you use every day.
* r e hester（编辑），r m哈里森（编辑），保罗illing（贡献者），迈克尔球（贡献者），罗伯特·伍德（贡献者），Derek Knight（贡献者），Carl Westmoreland（贡献者）
Edited by米歇尔A. Rivera., Animal Rights Expert