Use of Sequentially Administered Stable Lead Isotopes to Investigate Changes in Blood Lead during Pregnancy in a Nonhuman Primate (Macaca fascicularis)

Abstract

The effects of pregnancy on the flux of lead from maternal bone were investigated in five females from a unique colony of cynomolgus monkeys (Macaca fascicularis) which had been dosed orally with lead (approximately 1100-1300 /ig Pb/kg body wt) throughout their lives (about 14 years). Through the use of stable lead isotopes ^Pb, ^Pb, and ^Pb, it was possible to differentiate between the lead contributed to blood lead from the skeleton and the lead contributed from the current oral dose. Blood samples and bone biopsy samples taken before, during, and after pregnancy were analyzed for lead (total and stable isotope ratios) by thermal lonization mass spectrometry. Through the use of end-member unmixing equations, the contribution to blood of lead from maternal bone during pregnancy was estimated and compared to the contribution of lead from maternal bone before pregnancy. A 29 to 56% decrease in bone lead mobilization in the first trimester was followed by an increase in the second and third trimesters, up to 44% over baseline levels. In one monkey, the third-trimester increase did not reach baseline levels. In a single low-lead monkey, a similar decrease in the first trimester was followed by a 60% increase in the third trimester, indicating that a similar pattern of flux is seen over a wide range of lead concentrations. Analysis of maternal bone and fetal bone, brain, liver, and kidneys confirmed a substantial transplacental transfer of endogenous lead. Lead concentrations in fetal bone often exceeded maternal bone lead concentrations. From 7 to 39% of the lead in the fetal skeleton originated from the maternal skeleton, o 1977 society of Toxicology.Lead is a ubiquitous metal that continues to be of significant public health concern despite decades of study and regu-

Teeth reveal juvenile diet, health and neurotoxicant exposure retrospectively: What biological rhythms and chemical records tell us

“…For example, 7%-39% of lead in the fetal skeleton of macaque monkeys may be derived from the maternal skeleton. [27] Additional elemental sources in teeth include nonmilk liquids, solid foods, environmental dust, soil, and inhaled vapors. [23,28,29] When relating tooth chemistry to nursing behavior, nonmilk dietary inputs, and health, it is ideal to know: 1) how effectively specific elements are absorbed during digestion; 2) whether elements are selectively filtered out F I G U R E 1 Upper (maxillary) molar from a captive rhesus macaque (Macaca mulatta) shown from (A) front/mesial view and (B) top/occlusal view.…”

A pharmacokinetic model of lead absorption and calcium competitive dynamics

“…The lead deposit in adult bone can act to replenish lead eliminated from blood by excretion, even long after exposure has ended 22–26 . It can also act as a source of lead transfer to the fetus when maternal bone is resorbed for the production of the fetal skeleton 27–30 .…”

Contribution of house dust contamination towards lead exposure among children in Karachi, Pakistan

“…Bone lead can contribute to elevated blood levels long after the exposure ceases (Fleming et al, 1997). Studies have reported that conditions such as ageing (Drasch, Bohm & Baur, 1987), osteoporosis (Gulson, Palmer & Bryce, 2002), pregnancy (Lagerkvist et al, 1996;Maldonado-Vega et al, 1996;Schuhmacher et al, 1996;Franklin et al, 1997;Gulson et al, 1997), lactation (Gulson et al, 2003(Gulson et al, , 2004, menopause and postmenopause (Hernandez-Avila et al, 2000;Gulson, Palmer & Bryce, 2002;Berkowitz et al, 2004;Nash et al, 2004;Popovic et al, 2005) increase bone resorption and consequently also increase lead levels in blood. Lead can be transferred from the mother to the fetus (Goyer, 1990;Graziano et al, 1990;Carbone et al, 1998) and also from the mother to infants via maternal milk (Gulson et al, 1998b;Ettinger et al, 2006).…”