第一条原则是农药毒性原则。农药的毒性分剧毒、高毒、中毒、低毒四类,是依据对大白鼠的口服致死中量(LD50)划分的(即在实验室内强迫各供试组的大白鼠口服不同剂量的供试农药,使半数大白鼠致死的剂量)。每千克大白鼠口服量小于5毫克为剧毒,5～50毫克/千克为高毒,51～500毫克/千 The first principle is the principle of pesticide toxicity. Toxicity of pesticides divided into four categories of high toxicity, poisoning, poisoning, low toxicity, is based on the rat oral dose lethality (LD50) divided (that is, in the laboratory forced each test group of rats to oral different doses of Test pesticides, lethal dose of half of rats). The oral dose of less than 5 mg per kilogram of rats is highly toxic, 5 to 50 mg / kg is highly toxic, 51 to 500 mg /