Relationships Between External Exposures and Blood Lead Levels

Relationships Between External Exposures and Blood Lead Levels 

Studies indicate that the blood lead to air lead ratio is not constant over the range of concentrations normally encountered. Most of the studies indicated blood to have one to two times the concentration of air, with males having a slightly higher value than females, and children a slightly higher value than adults. More data are needed in the study of blood-air ratios in low air lead concentrations [73]. 

Observable increases in blood lead levels occur at soil or dust lead concentrations of 500-1,000 mg/1. There is a consistent 3%-6% increase in blood lead levels for a two-fold increase in soil lead levels, over a wide diversity of populations. In data observed, the largest estimate in the percentage increase in blood lead oc-curing in populations with the lowest lead levels [73]. 

In the analysis of two studies, for 40%-45% of confirmed cases of elevated blood lead levels in children, a possible source of lead paint hazard could not be located [73]. However, that should not weaken the role of lead-based paint as a major source of lead for children. The background contribution of lead from other sources is still not known even for children whose potential lead-paint hazard has been identified, making a discrimination of the lead proportion from either source impossible. 

---