Exposure of U.S. children to residential dust lead, 1999-2004: II. The contribution of lead-contaminated dust to children's blood lead levels.

BACKGROUND: The U.S. Centers for Disease Control and Prevention collected health, housing, and environmental data in a single integrated national survey for the first time in the United States in 1999-2004. OBJECTIVES: We aimed to determine how floor dust lead (PbD) loadings and other housing factors influence childhood blood lead (PbB) levels and lead poisoning. METHODS: We analyzed data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES), including 2,155 children 12-60 months of age with PbB and PbD measurements. We used linear and logistic regression models to predict log-transformed PbB and the odds that PbB was >or=5 and >or=10 microg/dL at a range of floor PbD. RESULTS: The population-weighted geometric mean (GM) PbB was 2.0 microg/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 in either the linear model [the proportion of variability in the dependent variable accounted for by the model (R2)=40%] or logistic model for 10 microg/dL (R2=5%). At floor PbD=12 microg/ft2, the models predict that 4.6% of children living in homes constructed before 1978 have PbB>or=10 microg/dL, 27% have PbB>or=5 microg/dL, and the GM PbB is 3.9 microg/dL. CONCLUSIONS: Lowering the floor PbD standard below the current standard of 40 microg/ft2 would protect more children from elevated PbB.

Evaluation of HUD-funded lead hazard control treatments at 6 years post-intervention.

The Evaluation of the HUD Lead-Based Paint Hazard Control Grant Program (Evaluation) was a HUD-funded study of the effectiveness of lead hazard control (LHC) treatments conducted by 14 grantees in communities across the country. A stratified random sampling scheme was used to select treated units at four grantee sites for continued environmental assessment at 6 years post-intervention. The study compared the relative effectiveness after 6 years of the different classes of interventions used by the grantees, after controlling for such factors as housing conditions and characteristics and resident and neighborhood characteristics. Geometric mean dust-lead levels on floors and window sills were 11% and 23% lower, respectively, at 6 years post-intervention than at any preceding point following the intervention. Although geometric mean window trough dust-lead levels were slightly higher at 6 years post-intervention than at other post-intervention time periods, they were still over 75% lower than before intervention. Treatment at more-intensive levels was associated with lower window sill and window trough dust-lead levels; however, statistical modeling found no significant difference in floor dust-lead loadings over time between the levels of treatment; however, significant differences in window sill and window trough dust-lead levels between treatment levels were evident. Findings from the 6-Year Extension study indicate that across all grantees and treatment strategies the treatments applied were effective at significantly reducing environmental lead levels on floors, window sills, and window troughs at least 6 years following the intervention.

Evaluation of lead hazard control treatments in four Massachusetts communities through analysis of blood-lead surveillance data.

This study utilized existing blood-lead surveillance data and records of housing properties treated for lead hazard control (LHC) in order to investigate the effectiveness of LHC treatments performed in four Massachusetts communities (Boston, Cambridge, Malden, and Springfield). This research is part of the US Department of Housing and Urban Development's (HUD) overall program evaluation strategy for assessing the effectiveness of their LHC Grant Program. Childhood blood-lead levels (BLLs) in housing units that were treated through HUD's LHC Grant Program were compared to BLLs in untreated matched control housing units. Data from multiple sources-local housing departments, local tax assessor departments, and the Massachusetts Department of Public Health-were linked to identify similar sets of treated and untreated dwellings. Geometric mean BLLs from before and after treatment were compared for the two sets of housing. Ten years of blood-lead surveillance data for children living in the selected dwellings were analyzed using log-linear mixed models and logistic regression models. Results indicate a 50% decline in BLLs in treated homes, a significantly larger decline than in untreated homes after adjusting for the general downward trend in BLLs observed in the general population for the last several years. Data show that homes that received HUD LHC treatments had children with blood-lead levels that declined twice as fast as in similar untreated homes. These findings show that LHC efforts are successful in reducing children's blood-lead levels.