The choice of animals in toxicological screening: inbred strains and the factorial design of experiment.

Abstract

Most toxicological screening is currently carried out using genetically variable "outbred" stocks, though the Carcinogenesis Bioassay Programme run by the National Cancer Institute uses a single inbred or F1 hybrid strain of mice and rats. The use of several inbred of F1 hybrid strains in a factorial experiment design would have a number of advantages over either of the current designs. The factorial experiment would need to be no larger, and would therefore not be significantly more expensive, but it would be statistically and biologically more powerful. It should lead to fewer false positive and false negative results, and it offers improved methods of interpreting the results of their significance to man. Eventually, inbred strains will become as widely accepted in toxicology as they are at present in immunology.