At 1, 2, 3, 4, and 5 dpf, embryos were examined for mortality and developmental malformations. Traditional endpoints of zebrafish teratology were scored, including arrested development, yolk sac edema, pericardial edema, red heart, deformities of the body axis, notochord aberrations, and malformations of craniofacial structures or the caudal fin (Fig. 2). Morphological assessments were quantified using a binary scale of either normal or abnormal morphology. For each exposure and each endpoint in the screen, the number of fish that were dead or exhibited a teratogenic effect was divided by the total number of fish within each group (n = 32 per exposure). If the incidence of mortality or of any individual teratogenic endpoint within any exposure group was more than 30% greater than that observed for the DMSO controls within the same spawn, it was considered a hit
