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Lead in plasma and whole blood from lead-exposed children
I A Bergdahl1, M Vahter, S A Counter
1Department of Occupational and Environmental Medicine, Lund University, Lund, SE-221 85, Sweden.
Insights
Plasma lead (Pb-P) may be a better indicator of lead exposure and toxicity than whole-blood lead (Pb-B) in children. High lead levels can saturate binding sites, potentially underestimating risk using Pb-B alone.
Area of Science:
- Environmental Health
- Toxicology
- Pediatrics
Background:
- Lead exposure is a significant public health concern, particularly in children.
- Assessing lead exposure and its associated risks relies on accurate biomarkers.
- Previous studies have primarily used whole-blood lead (Pb-B) concentrations.
Purpose of the Study:
- To compare the utility of plasma lead (Pb-P) and whole-blood lead (Pb-B) as indicators of lead exposure in children.
- To investigate the relationship between Pb-P, Pb-B, and hematological parameters.
- To evaluate potential differences in lead biomarker relationships between children and adults.
Main Methods:
- Measured Pb-P and Pb-B concentrations in children with varying lead exposure levels.
- Analyzed the correlation between Pb-P and Pb-B using regression analysis.
- Assessed the association of these lead biomarkers with free erythrocyte protoporphyrins and hemoglobin concentrations.
- Compared findings with existing adult data.
Main Results:
- A nonlinear relationship was observed between Pb-B and Pb-P, with Pb-B increasing less as Pb-P rose.
- A strong association was found between Pb-B and log Pb-P (r=0.95).
- Pb-P and Pb-B were both significantly associated with free erythrocyte protoporphyrins and hemoglobin levels.
- No major differences were noted in the Pb-B/Pb-P relationship between children and adults.
Conclusions:
- Plasma lead (Pb-P) may serve as a more relevant indicator of lead exposure and hematotoxicity than whole-blood lead (Pb-B), especially at high lead levels.
- The nonlinear Pb-B/Pb-P relationship suggests saturation of lead binding sites in red blood cells, potentially leading to underestimation of risk from Pb-B.
- These findings highlight the importance of considering Pb-P for a more accurate assessment of lead exposure and associated health risks in children.
Abstract:
In 31 children exposed to lead and 13 considerably less exposed children ("unexposed"), the plasma (Pb-P) concentrations ranged from 0.46 to 18.4 (median, 2.4) and from 0.14 to 0.38 (median, 0.21) microg/L, respectively. Corresponding whole-blood concentrations (Pb-B) were 99-920 (median, 370) and 39-120 (median, 66) microg/L, respectively. The relation between Pb-B and Pb-P was nonlinear; when Pb-P rose, the Pb-B increased relatively less. There was a close association between Pb-B and log Pb-P (r=0.95; P=0.0001). When these data were compared to previous data on adults, there was no major difference between children and adults in the Pb-B/Pb-P relation. Free erythrocyte protoporphyrins in blood were associated with Pb-P (r=0.75; P=0.0001) and Pb-B (r=0.90; P=0.0001). Also, there was an association between blood-hemoglobin concentration and Pb-P in both exposed (r=-0.67; P=0.0001) and unexposed (r=-0.67; P=0.01) children; the corresponding figures for Pb-B were r=-0.42; P=0.02, and r=-0.80; P=0.001, respectively. Thus, at least with regard to toxicity on hematopoiesis at high lead levels, Pb-P may be a more relevant indicator of exposure and risk than Pb-B. Because the curved Pb-B/Pb-P relation indicates a saturation of binding sites for lead in red cells, exposure and risk at high lead levels may easily be underestimated from Pb-B data.