Investigations of factors influencing exposure and response to lead, mercury, and cadmium in man and in animals.

The susceptibility of the heme biosynthetic pathway to lead, as reflected by increased free erythrocyte porphyrin (FEP) concentration, is in humans as well as in rats in the order of young greater than or equal to female greater than male. The difference between adult male and female rats can be explained at least partially by the interaction of estradiol and progesterone with the FEP response to lead; the hormonal influence on FEP does not seem to be mediated through changes in plasma iron. The classical "tubular type" proteinuria in workers chronically exposed to cadmium has two not necessarily concomitant components, namely, a tubular type and a glomerular type component characterized by increased excretion of low and high molecular weight proteins, respectivley. No synergistic effect of cadmium and lead on the proteinuria of workers simultaneously exposed to both metals was observed. Mercury (most likely methylmercury) is freely transferred from the mother to the fetus; there is only a slight placental barrier for lead and a rather strong one for cadmium. Compared to maternal blood, placenta does not accumulate lead or mercury but concentrates cadmium about 10-fold.