The Relationship of Dust Lead to Blood Lead Levels

Lead poisoning effects on newborns include premature birth, low birth weight, and brain damage.

Goals: The objectives of this study were: to determine whether dust lead loading (ug/ft²) or dust lead concentration (ug/g) is a better predictor of children's blood lead levels; to investigate whether dust sampling using vacuum methods or a wipe method is more predictive of children's blood lead levels; to identify which interior household surface(s) should routinely be sampled for dust lead measurements; and to estimate the probability of a child having an elevated blood lead level on the basis of a known level of lead in house dust, controlling for other potential exposures.

Description: Lead contaminated house dust was first recognized as an important source of lead for urban children over 20 years ago.  The Residential Lead Hazard Control Act of 1992 (Title X) requires the Environmental Protection Agency to promulgate a health-based dust lead standard for residential dwellings, which would identify the dust lead levels above which it is dangerous for children to be exposed.  HUD contracted with the Center to develop this study in order to provide the federal government with data that could be used in setting this standard.

Identification and recruitment of eligible subjects was done by using lists of sequential births between March 1, 1991 and September 30, 1992 from three urban hospitals in Rochester, New York. Eligible children were in the 1 to 22 month age range. Stringent eligibility requirements were imposed to assure that the child's residential environment was the principal likely source of lead exposure. A cross-sectional study design was employed to investigate the relation of lead-contaminated house dust, other potential environmental sources of lead, and urban children's blood lead levels. Field work was done from August through November 1993.

Three dust collection methods were used to obtain side-by-side samples from as many as 12 sampling locations in each house (i.e., a maximum of 36 samples). Two vacuum methods were used to determine both dust lead concentration and dust lead loading: an inline filter method (the Dust Vacuum Method), and a cyclone-type sampler with a much higher flow rate (the Baltimore Repair and Maintenance study vacuum method). Wipe sampling, which only measures dust lead loading, was also conducted. Thus, there were five dust collection method variables (Dust Vacuum Method dust lead concentration, Dust Vacuum Method dust lead loading, Baltimore Repair and Maintenance vacuum method dust lead loading, Baltimore Repair and Maintenance vacuum method dust lead concentration, and wipe dust lead loading).

The study was developed in collaboration with HUD, EPA, and  CDC, and conducted in 1993 by Dr. Bruce Lanphear and the Lead-in-Dust study group at the University of Rochester School of Medicine.

Results and Conclusions: Dust lead loading is a better predictor of children's blood lead levels than is dust lead concentration for the range of lead-contaminated dust and blood lead levels observed in this study. Any household dust lead standard should be linked to the method by which dust is sampled, because the relationship between children's blood lead levels and dust lead levels varies significantly by method of dust collection. The relationship between blood lead levels and household dust lead is different for floors, window sills, and window troughs using the same dust collection method, indicating that different standards are needed for each surface. To determine if a housing unit is safe for children, non-carpeted floors and interior window sills or window troughs can be measured using either the Baltimore Repair and Maintenance vacuum method or wipe sampling method.

In addition to the dust collection method, the following covariates were found to be significantly associated with higher blood lead levels among children:  Black race, parental reports that children put soil in their mouths, single parent household, and a higher ferritin level.

Settled, lead-contaminated house dust (at levels observed in this study) is an important contributor of lead to children who have low level elevation of blood lead levels (i.e., blood lead levels up to 20 ug/dL). This study suggests that the proportion of urban children having a blood lead level exceeding 10 ug/dL increases at levels lower than current HUD post-abatement clearance standards and the recently released EPA guidance levels. Future research should seek to confirm the estimated relationship between children's blood lead levels and lead contaminated house dust found in this study. Also, further research should investigate whether dust control is associated with a meaningful decrease in blood lead levels of children at today's lead exposures.

For more information contact Jonathan Wilson at jwilson@centerforhealthyhousing.org.

Publications:

You may download the Executive Summary in Acrobat (.pdf) format.(File size 27k.)

Research and Evaluation
(Active Projects)

Research and Evaluation
(Completed Projects)

Training and Technical Assistance
(Active Projects)

Training and Technical Assistance
(Completed Projects)

Demonstration

Policy