Developmental toxicity of dinocap in the mouse is not due to two isomers of the major active ingredients.

Abstract

Technical-grade dinocap, a complex-mixture fungicide, is teratogenic in the CD-1 mouse, causing cleft palate and otolith defects. In this study we compared the developmental toxicities of 2,4-dinitro-6-(1-methylheptyl)phenyl crotonate and 2,6-dinitro-4-(1-methylheptyl)phenyl crotonate, model isomers of the major active ingredients of technical dinocap, to the known teratogenicity of the technical compound. Individual isomers, both isomers combined, or technical dinocap were administered to pregnant mice on days 7-16 of gestation. Some dams were killed at term and litters were removed, dead fetuses and resorptions were counted, and live fetuses were weighed and preserved in Bodian's fixative for examination for cleft palate. Other treated dams were allowed to give birth: postnatal viability and growth, development of swimming behavior, and otolith formation were evaluated. As in previous studies, technical-grade dinocap caused cleft palate and weight deficits in fetuses at term and increased neonatal mortality and abnormal swimming behavior, torticollis, and deficient otolith formation in surviving pups. Neither of the purified isomers exhibited any developmental toxicity when administered under identical conditions. Thus, it is concluded that these isomers are not the active teratogenic component(s) in technical-grade dinocap.