Modelling of environmental lead contributors to blood lead in humans

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Abstract
The Second National Health and Nutrition Examination Survey (NHANES II) is the only representative national study of body burden of lead where detailed concurrent information is available on a number of geographic and socio-economic factors. To date, however, reliable information on concurrent local environmental lead exposure for the sample has been lacking. In this study, we have identified and utilized previously unused concurrent lead exposure data. Our exposure data include time and region specific information on sales of lead from gasoline and ambient air-lead measurements from the United States Environmental Protection Agency (EPA). In addition, we have included information on lead consumed in food from the United States Food and Drug Administration (FDA). Our results indicate weak but significant associations between state sales of lead from gasoline and blood lead. In addition, we found a significant association between ambient air lead measurements and blood-lead concentrations. Socioeconomic factors and life-style factors were significantly related to blood lead, controlling for other possible confounders. Overall, our model explained 34% of the variance in blood-lead levels, which is a significant improvement compared to the maximum of 25% from other studies using the NHANES II data. The study substantiates prior findings that the majority of the variance in overall blood lead is significantly related to lead sources other than gasoline. From a public health perspective, it is therefore imperative that lead screening programs be continued and focused on multiple sources of lead, including lead in gasoline. The study supports prior findings of a continuous decrease in blood lead, independent of decreases of lead from gasoline. Moreover, we demonstrated the importance of other environmental and life-style-associated factors in predicting blood-lead levels. Further attention should be directed to assess other contributory sources of blood lead in addition to those used in this paper.