Chemical Protection against Ionizing Radiation: I. Sampling Methods for Screening Compounds in Radiation Protection Studies with Mice

Abstract

Sampling is based on the method of sequential analysis of Wald; the sample size is not fixed in advance, but instead, depends upon the outcome of the experiment. The odds ratio is used as a measure of the difference between control and experimental groups. Control over risks of falsely judging compounds as protective as well as overlooking a protection compound is provided. A maximum of 15 mice given the test compound prior to a lethal dose of X-radiation is needed to separate effective from ineffective compounds. For chemical toxicity tests the "up and down" method allowed the LD50 to be estimated, usually within 5%, with only 10 mice. This screening method was more economical of mice and time than other conventional procedures.