Lead Dust and Blood Lead Analysis Using NHANES

Project Funders: U.S. Department of Housing and Urban Development (HUD)

Project Partners: The U.S. Department of Housing and Urban Development (HUD), Healthy Housing Solutions, and Battelle Memorial Institute
Project Contact: David E. Jacobs, djacobs@nchh.org, 410.992.0712

Project Description: Lead-contaminated house dust is a major source of lead exposure for children in the U.S. The results of this study show that floor lead dust between 6 μg/ft² and 12 μg/ft² using wipe sampling can be expected to protect most children living in pre-1978 homes from having a blood lead level greater than or equal to 10 µg/dL. Protection at lower blood lead levels would require even lower dust lead levels. These findings show that the current EPA dust lead exposure limits are too high to protect children adequately. From 1999 to 2004, the National Health and Nutrition Examination Survey (NHANES), with funding from the U.S. Department of Housing and Urban Development, collected dust lead loading (PbD) samples from the homes of children aged 12-60 months. In this study, the population-weighted geometric mean (GM) blood lead level was 2.0 μg/dL (geometric standard error = 1.0). Age of child, race/ethnicity, serum cotinine concentration, poverty-to-income ratio, country of birth, year of building construction, floor PbD by floor surface and condition, windowsill PbD, presence of deteriorated paint, home-apartment type, smoking in the home, and recent renovation were significant predictors of dust lead. At a floor dust lead level of 12 μg/ft², the models predicted that the GM blood lead level was 3.9 μg/dL.

The population weighted geometric mean floor and windowsill PbD were 0.5 μg/ft² and 7.6 μg/ft², respectively. Only 0.16% of the floors and 4.0% of the sills had PbD at or above current federal standards of 40 and 250 μg/ft², respectively. Income, race/ethnicity, floor surface/condition, windowsill PbD, year of construction, recent renovation, smoking, and survey year were significant predictors of floor PbD. A similar set of predictors, plus the presence of large areas of exterior deteriorated paint in pre-1950 homes and the presence of interior deteriorated paint, explained 20% of the variability in sill PbD. Most houses with children have PbD far below federal standards. At a floor dust lead level of 12 μg/ft², the results show that 4.6% of children living in homes constructed before 1978 are predicted to have blood lead levels ≥ 10 μg/dL, 27% have PbB ≥ 5 μg/dL and the geometric mean PbB is 3.9 μg/dL.

In short, the study shows that lowering the floor dust lead standard below the current standard of 40 μg/ft² would protect more children from elevated blood lead levels. Historically, allowable PbD levels have declined as research has progressed. In the early 1990s, Maryland enacted a floor PbD standard of less than or equal to 200 μg/ft² (Code of Maryland, 1988). EPA issued guidance in 1995 lowering the floor PbD level to ≤ 100 μg/ft². And in 1999-2001, HUD and EPA promulgated a floor PbD standard of less than or equal to 40 μg/ft², which has remained unchanged as of 2017. However, in early 2017, HUD recently issued guidance lead dust levels for its lead hazard control grantees of 10 µg/ft² on floors, as well as new porch floor dust lead guidance (see link below).

Resources:

U.S. Children’s Exposure to Residential Dust Lead, 1999-2004: I. Housing and Demographic Factors Associated with Lead-Contaminated Dust [pdf]

U.S. Children’s Exposure to Residential Dust Lead, 1999-2004: II. The Contribution of Lead-Contaminated Dust to Children’s Blood Lead Levels [pdf]

Análise de chumbo e chumbo de chumbo usando NHANES: “Lead Dust and Blood Lead Analysis Using NHANES” was translated into Portuguese by Artur Weber and Adelina Domingos. Note that this article was not translated by NCHH; therefore, we cannot be responsible for any errors or omissions in the translation. [url; Homeyou, 2017]

Revised Dust-Lead Action Levels for Risk Assessment and Clearance Clearance of Porch Floors [pdf; HUD, 2017]