Abstract
The single peroral dose toxicity of 26 chemicals was estimated each year for 12 years to determine the reproducibility of the test and of commercial production. For 11 years the resultant median lethal doses were relatively unaffected by the different samples of each chemical received annually, by changes in the stock of rats, by the diluted or undiluted state of the materials, or by the change of personnel performing the tests. Only one variable, the weight of the rat, appeared to have a significant effect on the LD50.