National Toxicology Program

As part of its charge to test chemicals of concern for potential toxicity the National Toxicology Program (NTP) evaluates reproductive toxicity using the study design termed Reproductive Assessment by Continuous Breeding (RACB). This two-generation study design was developed by the NTP for use in identifying potential hazards to toxic effects on male and/or female reproduction, to characterize that toxicity, and to define the dose-response relationships for each compound. The study design has evolved over the years that it has been used, initially the study employed predominantly mice as the test species and now almost exclusively uses rats. As our improved knowledge and use of sensitive end points has increased, these have been incorporated into revisions of the study design.

For all studies, however, the RACB design has a series of interrelated tasks that can be amended as the study data are produced, though not all parts are preformed for all chemicals.

Reference:

Robert E. Chapin and Richard A. Sloane. Reproductive Assessment by Continuous Breeding: Evolving Study Design and Summaries of Ninety Studies. Environ Health Perspect 105(Suppl 1):199-395 (1997). (html version; pdf version)