 the integrated exposure uptake biokinetic ( ieubk ) model , recommended for use by the u.s . 
 environmental protection agency at residential superfund sites to predict potential risks to children from lead exposure and to establish lead remediation levels , requires an interindividual geometric standard deviation ( gsdi ) as an essential input parameter . 
 the gsdi quantifies the variability of blood lead concentrations for children exposed to similar environmental concentrations of lead . 
 estimates of potential risks are directly related to the gsdi , and therefore the gsdi directly impacts the scope of remediation at superfund sites . 
 site - specific gsdi can be calculated for sites where blood lead and environmental lead have been measured . 
 this paper uses data from blood and environmental lead studies conducted at the bingham creek and sandy , utah , superfund sites to calculate gsdi using regression modeling , box modeling , and structural equation modeling . 
 gsdis were calculated using various methods for treating values below the analytical method detection and quantitation limits . 
 treatment of nonquantifiable blood lead concentrations affected the gsdi more than the statistical method used to calculate the gsdi . for 
 any given treatment , the different statistical methods produced similar gsdis . because of the uncertainties associated with data in the blood lead studies , we recommend that a range of gsdis be used when analyzing site - specific risks associated with exposure to environmental lead instead of a single estimate . because the different statistical methods produce similar gsdis , we recommend a simple procedure to calculate site - specific gsdi from a scientifically sound blood and environmental lead study.imagesfigure 1 
Images