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, email@example.com, 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 can be expected to protect most children living in pre-1978 homes from having a blood lead level ≥ 10 µg/dL. Protection at lower blood lead levels would require even lower dust lead levels. These findings show that the current federal dust lead exposure limits are too high to protect children adequately.
In 1999-2004, 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. The population weighted geometric mean floor and window sill 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, window sill 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 1990’s, Maryland enacted a floor PbD standard of ≤ 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 ≤ 40 μg/ft², which has remained unchanged.