Environmental exposure to cadmium and human birthweight

Fetal toxicity of cadmium (Cd) is well documented in rodents. However, little information is available regarding the human fetus. To investigate the effect of low levels of Cd on the human placenta and the consequences on birthweight, we conducted a study of 102 mothers and their newborns in an obstetrical care unit. Placental and hair samples were collected at delivery to determine Cd concentrations. The main finding of this study was the relationship between a decrease in birthweight and an increase of newborn hair Cd which varied in the presence of placental calcification. In cases of parenchymal calcifications, placental Cd levels were higher (Wilcoxon test, P < 0.05) and newborn hair Cd levels were lower (Wilcoxon test, P < 0.01) than in the absence of calcification. These relationships remained significant even after taking into account smoking habits and gestational age. In the presence of calcification, an increase in the level of Cd in newborn hair was related to a decrease in birthweight which was independent of placental Cd concentration (rpartial = -0.49, P < 0.01). In the absence of calcification, a decrease in birthweight was observed for the upper values of newborn hair Cd (r = -0.44, P < 0.05 when Cd > or = 0.3 ppm). The difference in birthweight between infants in the first and last quartiles of newborn hair Cd was 472 g in cases of calcifications and 122 g in the absence of calcification. Other placental parameters were not significantly related to placental Cd concentration.