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DETERMINANTS OF RESIDENTIAL LEAD EXPOSURE
Citation:
Egeghy, P P., S. Catlin, P. B. Ryan, AND J J. Quackenboss. DETERMINANTS OF RESIDENTIAL LEAD EXPOSURE. Presented at International Society of Exposure Analysis, Stresa, Italy, September 21-25, 2003.
Impact/Purpose:
The NHEXAS analysis projects being conducted by NERL address the following scientific issues/questions:
- Do exposure distributions vary by demographic group?
- What is the impact of censoring (BDL) on multimedia distributions and associations?
- Which questionnaire/diary items are most useful in explaining variability or identifying "high exposure" groups?
- How do exposure classifications and measurements compare in their ability to explain variability in exposures and biomarkers?
- Can changes in exposures over time be explained by dietary and questionnaire/activity information?
- How well do NHEXAS findings compare with existing models/assessments (e.g., NATA)?
Description:
The phase-out of leaded gasoline, and the accompanying decrease in lead emissions, resulted in a dramatic decline in mean blood lead levels from the late 1970s through the early 1990s. Nonetheless, lead exposures remain a public health concern. Long-term exposures to even low-levels adversely affect the hematopoietic and central nervous systems, and environmental sources often include the home. The National Human Exposure Assessment Survey in Maryland (NHEXAS-MD), a longitudinal study of multimedia exposure to metals, pesticides, and polycyclic aromatic compounds, aimed to identify sources of exposure and activities associated with elevated exposures. Regression analyses of concentrations and questionnaires responses were performed for lead concentrations in indoor air, dust, and dermal wipes using mixed-effects models. Significant factors associated with increased indoor air lead concentrations included outdoor air concentrations, open window periods, age of housing, and painting activities. Pet ownership and air filter use were associated with decreased concentrations. Significant predictors of lead dust loadings included lead soil concentrations, open window periods, chipping interior paint, age of house, and fireplace use. Concrete entrance and frequency of indoor pesticide use were also significant, but were perhaps surrogates for other factors. Concentrations of lead measured in dermal wipes were associated with overall dust level in residence, bathing/washing activities, time spent outside at home, skin contact with dirt or soil, proximity to commercial areas, and gender. In all three models, significant predictors included both time-varying factors (including activities) and factors fixed over time (including housing characteristics).
This work has been funded wholly or in part by the United States Environmental Protection Agency. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.