Assessment of bone lead during pregnancy: a pilot study

More than 85% of American children raised in the 1970s had blood lead (BPb) levels >/=10 microg/dL, the level that currently defines childhood Pb poisoning. With exposure and absorption Pb accumulates in bone. Bone Pb release back to blood also occurs, particularly when kinetic rates of bone turnover are elevated. We examined a group of childbearing age, urban African American and Hispanic women to determine whether they had measurable bone Pb and whether bone Pb levels changed during pregnancy. Tibial bone Pb content was assessed sequentially 3 times over 4 months by L-line X-ray fluorescence (LXRF); for pregnant enrollees this occurred during the second and third trimesters and 1-2 months postpartum. LXRF is a noninvasive, low-dose radiation technique that measures superficial cortical bone Pb. Other measures included age, years living in New York City, BPb and a home Pb assessment employing KXRF methodology. Of 53 women evaluated 34 were pregnant. Of these 34, 2 had blood Pb levels >/=10 microg/dL; 2 had bone Pb levels above the minimum detection limit of the instrumentation at the time of enrollment. A case report is presented in which a declining bone Pb level was accompanied by an increase in BPb concentration. We surmise that the prevalence of elevated bone Pb levels will be low in Bronx women despite long-term exposure to leaded paint. However, fetuses of those with elevated bone Pb are at risk of excessive in-utero Pb exposure.