Cadmium, lead, and selenium in cord blood and thyroid hormone status of newborns.

Cadmium (Cd), lead (Pb), and selenium (Se) concentrations in cord whole blood, sampled from 24 women at the time of delivery in a hospital in Tokyo in 2005, were determined by inductively coupled plasma mass spectrometry with a reaction cell. Signal enhancement caused by nonspectroscopic interference for Se was evident and the standard addition technique was essential for correcting the interference. Median concentration in cord bloods was 0.20 ng/g, 6.7 ng/g (0.67 microg/dL), and 191 ng/g for Cd, Pb and Se, respectively. Lead concentration was lower, whereas Se concentration was higher, than those reported in other countries. The trace element concentration was related to the levels of thyroid stimulating hormone (TSH) and free thyroxin (fT4) in the neonatal blood sampled at 4-6 days postpartum. A significantly negative correlation was observed between Cd concentrations in cord blood and TSH concentration in neonatal blood. The result indicated the possible effect of in utero Cd exposure on thyroid hormone status of newborns and that Cd exposure level should be assessed as a covariate in the survey on the relationship between in utero chemicals (e.g., PCBs) exposure and thyroid hormone status.

Thyroid hormone status of newborns in relation to in utero exposure to PCBs and hydroxylated PCB metabolites.

The associations between in utero exposure to polychlorinated biphenyls (PCBs) or hydroxylated PCB metabolites (OH-PCBs), and free thyroxin (fT4) or thyroid-stimulating hormone (TSH) status in the newborn were investigated as a pilot study of a large-scale epidemiologic study on in utero PCB or OH-PCB exposure and thyroid function of the newborns. Umbilical cord tissue was used as the media for the biological monitoring of PCBs/OH-PCBs exposure in utero. For the measurement of fT4 and TSH, a heel-prick blood sample spotted on filter paper, which is called Guthrie card, is collected from each neonate at day 4-6 postpartum for this study when the mass screening sampling was performed. We showed that the concentration of total OH-PCBs and one of the OH-PCB congeners (OH-PCB 187) was related significantly to higher fT4 level of newborns. On the other hand, the concentration of total PCBs and PCB congeners (PCB 118, 138, 153, and 180) showed no relationship with fT4 and TSH level of the newborns. The results obtained in this pilot study indicated the possibility that in utero OH-PCBs exposure affects thyroid hormone status of newborns.