Lead and cadmium concentrations in maternal and umbilical cord blood, amniotic fluid, placenta, and amniotic membranes

The lead and cadmium concentrations in maternal and umbilical cord blood and amniotic fluid were determined in 19 parturient women at delivery. Six placental and amniotic membrane tissue specimens were also investigated. The mean lead concentrations (mean +/- SD) in maternal (40.4 +/- 18.2 ng/ml) and umbilical cord (37.1 +/- 13.5 ng/ml) blood were similar and correlated significantly with each other (r = 0.77, p less than 0.001). The lead concentration in amniotic fluid (59.6 +/- 8.3 ng/ml) was significantly higher than in maternal or umbilical cord blood. Cadmium concentrations in maternal blood (1.1 +/- 0.9 ng/ml) and amniotic fluid (1.0 +/- 0.2 ng/ml) were significantly higher (p less than 0.001) than in umbilical cord blood (0.4 +/- 0.2 ng/ml) and there was no significant correlation among these values. The highest concentrations of cadmium (35.1 +/- 24.2 ng/gm of wet weight) and lead (87.3 +/- 154.2 ng/gm of wet weight) were found in the amniotic membranes. Our results show that lead and cadmium accumulate in amniotic fluid and amniotic membranes and that the distribution of lead and cadmium is different in the human maternal-fetoplacental unit. The fetal exposure to lead is similar and that to cadmium, lower, compared with maternal exposure. The inability of the placenta to totally prevent the fetus from exposure to lead and cadmium suggests that pregnant women should avoid occupations where exposure to these toxic elements is possible.