Bone lead

In both procedures, a concern is the extent to which the poly(ethylene) undergoes wear within the artificial joint. The constant rubbing of metal on polymer is capable of generating particles of wear debris, and these can collect around the joint. In extreme cases, this debris can interfere with the metabolic processes in the remaining bone, leading to bone resorption and... 

Figure 5. Development of U concentration profiles during a leaching scenario, D/R=10. Here diffusive uptake occurs for 10 ky at a relative groundwater concentration of 10 after which the concentration is dropped to 1. U is lost initially from the outer portions of the bone, leading to distinctive M- and n-shaped profiles. [Used by permission of Elsevier Science, from Pike et al. (2002), Geochim Cosmochim Acta, Vol. 66, Fig. 3f, p. 4276.]...

Renal function in workers exposed to lead has also been examined in relation to bone lead, since this measurement of exposure provides a better assessment of cumulative dose of lead to the kidneys than... 

Absorption of lead may increase during pregnancy. An increase in lead absorption may contribute, along with other mechanisms (e.g., increased mobilization of bone lead), to the increase in PbB concentration that has been observed during the later half of pregnancy (Gulson et al. 1997 Lagerkvist et al. 1996 Schuhmacher et al. 1996). 

In human adults, approximately 94% of the total body burden of lead is found in the bones. In contrast, bone lead accounts for 73% of the body burden in children (Barry 1975). This large pool of lead in adults can serve to maintain blood lead levels long after exposure has ended (Flemming et al. 1997 ... 

The results from more recent studies have not clarified the issue. In a study of the general population in Belgium in which 2 sets of data were collected at a 6-year interval, Staessen et al. (1996) found that blood pressure was not correlated with PbB or ZPP concentrations in men or women. The study further found that the risk of becoming hypertensive was not associated with PbB or ZPP concentrations measured at the first data collection. Results from the evaluation of participants in the Normative Aging Study showed that an increase in tibia bone lead of about 29 pg/g was associated with an increased odds ratio of hypertension of 1.5 (Hu et al. 1996a). However, the authors acknowledged that the procedures used to... 

The low concentrations of lead in plasma, relative to red blood cells, has made it extremely difficult to accurately measure plasma lead concentrations in humans, particularly at low PbB concentrations (i.e., less than 20 pg/dL). However, more recent measurements have been achieved with inductively coupled mass spectrometry (ICP-MS), which has a higher analytical sensitivity than earlier atomic absorption spectrometry methods. Using this analytical technique, recent studies have shown that plasma lead concentrations may correlate more strongly with bone lead levels than do PbB concentrations (Cake et al. 1996 Hemandez-Avila et al. 1998). The above studies were conducted in adults, similar studies of children have not been reported. 

An analysis of eight cross-sectional and/or prospective studies which reported tooth lead and PbB levels of the same children found considerable consistency among the studies (Rabinowitz 1995). The mean tooth lead levels ranged from under 3 to over 12 pg/g. In a study of 63 subjects, dentin lead was found to be predictive of concentrations of lead in the tibia, patella, and mean bone lead 13 years after tooth lead assessment in half of them (Kim et al. 1996b). The authors estimated that a 10 pg/g increase in dentin lead levels in childhood was predictive of a 1 pg/g increase in tibia lead levels, a 5 pg/g in patella lead levels and a 3 pg/g increase in mean bone lead among the young adults. 

Women. Studies of women suggest that conditions of pregnancy, lactation, and osteoporosis may intensify bone demineralization, thus mobilizing bone lead into the blood resulting in increased body burdens of lead (Silbergeld et al. 1988). For example, women show an increased rate of bone lead loss with age relative to men (Drasch et al. 1987). Women with postmenopausal osteoporosis may be at an... 

Most of the body burden of lead resides in bone a portion of the maternal bone lead stores is transferred to the fetus during gestation and incorporated into fetal bone during the development of the fetal skeleton. 

Hu H Department of Environmental Health, Boston, MA Measure in vivo bone lead level in a National Institute of new longitudinal study of lead exposure Environmental Health and reproduction among married Sciences women and men ... 

Me Michael AJ University of Adelaide, Adelaide, Australia Investigate the relative contribution to the infant in utero of mother s current environmental lead compared with mobilization of lead from maternal stores, especially bone lead National Institute of Environmental Health Sciences... 

Rothenberg SJ Charles R. Drew University of Medicine Science, Los Angeles, CA The role of prepregnancy maternal bone lead and prenatal maternal blood lead upon alterations in infant saccadic and smooth pursuit eye movements National Institute of General Medical Sciences... 

Schwartz BS John Hopkins University School of Hygiene Public Health, Baltimore, MD Study of the relations among BLLS, DMSA-chelatable lead, bone lead, and health effects (heme synthesis, renal early biologic effects and function, blood pressure, and CNS and PNS function) in lead workers in South Korea National Institute of Environmental Health Sciences... 

Wolff MS Mount Sinai School of Medicine of CUNY, New York, NY Analytical support for comprehensive assessment of lead exposures body burden measures will include blood lead, plasma lead, ZPP, bone lead, representing multiple compartments for deposition of lead and widely variable rates of elimination measurement of total lead in soil extracts to validate quantitative measures National Institute of Environmental Health Sciences... 

Batuman V, Wedeen RP, Bogden JD, et al. 1989. Reducing bone lead content by chelation treatment in chronic lead poisoning An in vivo X-ray fluorescence and bone biopsy study. Environ Res 48 70-75. 

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