• White Paper

Species/strain/stock in endocrine disruptor assays


Parker, S. P., & Tyl, R. W. (2003). Species/strain/stock in endocrine disruptor assays.


This white paper is a review of the interspecies and intraspecies similaritiesand differences in endocrine endpoints in the absence and presence of test chemicals, in order to determine whether specific species/strains should be preferred or avoided when screening for endocrine activity. There is much evidence that different species and strains within species exhibit differing sensitivities to endocrine-active compounds, specific for chemicals and endpoints evaluated. Thus selection of appropriate species and strain(s), or at least understanding the differential responsivity of them is crucial todetecting effects in animal models which are extrapolable to human risk. This white paper is limited to the species being considered for inclusion in the Endocrine Disruptor Screening Program (EDSP) and also limited in scope to the endocrine endpoints under consideration. Currently, the reproductive and developmental toxicology Environmental Protection Agency (EPA) guideline studies recommend using the rat and not strains with low fecundity. The most commonly used rat strain for these Guideline studies is the CD Sprague-Dawley (SD) rat (the CD-1 Swiss mouse is also frequently used). Though the majority of historical data exists in this species/strain, there is evidence that endocrine-active chemicals may have very different dose-response curves for certain endocrine-related reproductive endpoints, which may, in part, be due to a differential sensitivity of different species/strains and endpoints in these species/strains to these chemicals. Since confounding factors make interlaboratory comparisons of dataproblematic, multi-strain studies conducted under the same experimental conditions and same laboratory were primarily used in the species/strain/stock comparisons.