Availability of toxic trace metals to the conceptus.

Energy production releases numerous toxic metals into the environment. Among those metals which have been shown to be toxic to the conceptus are cadmium, lead, mercury, plutonium and vanadium. This paper reviews the results from the authors' studies of pregnant rats exposed to these metals by parenteral administration, inhalation or gastric intubation. In addition, direct measurements were made of maternal blood flow and clearance of metals across the guinea pig placenta to serve as conceptual examples of factors which regulate the effects of the metals on the fetus. Discussion includes the influence of route of maternal exposure and subsequent absorption, gestational age at exposure, metal behavior in the maternal bloodstream, movement of metals across the placenta, and distribution of metals in the products of conception.