Transfer of lead via placenta and breast milk in human.

The mean lead levels in the maternal blood, cord blood, breast milk and placental tissue, were 0.63 mumol/L (13.2 micrograms/dL), 0.33 mumol/L (6.90 micrograms/dL), 4.74 micrograms/L and 0.86 mumol/kg (17.85 micrograms/100 g) respectively for 165 parturient women occupationally non-exposed to lead in 2 hospitals in Shanghai. No significant difference was found between maternal age groups for these indicators. However, the lead levels in the cord blood and breast milk increased with the lead level in the maternal blood, with coefficient of correlation of 0.714 (P < 0.0001) and 0.353 (P < 0.01) respectively. The mean concentration of lead in breast milk for 12 occupationally lead exposed women was 52.7 micrograms/L, which was almost 12 times higher than that for the occupationally non-exposed population. These results suggested that transfer of lead via placenta prenatally and breast milk postnatally were possible and might pose a potential health hazard to the fetuses and the neonates.