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.