Prenatal effects of herbicides: evaluation by the prenatal development index.

The herbicides 2,4-D and 2,4,5-T and many of the esters of these compounds produced cleft palates in CD-1 mice. Silvex and Agent Orange also produced cleft palates. Depending on the dose and means of administration variable responses relating to the production of cleft palates, effect on fetal weight, and effect on fetal mortality were obtained. In order to view these data comprehensively, the Prenatal Development Index was determined. This index was computed from the incidence of malformed fetuses, fetal mortality and fetal body weight. This made it possible to evaluate data from some experiments with feto-toxic doses of compounds in which the high incidence of fetal mortality and consequently low incidence of viable fetuses obscured the response.