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Executive Summary EPA 747-R-98-002
Comprehensive Abatement Performance Pilot Study
This report presents the results of the statistical analysis of multi-element data collected during a pilot study that preceded the Comprehensive Abatement Performance (CAP) Study. The goal of the CAP Study was to assess the long-term efficacy of lead-based paint abatement. The pilot study was conducted to test the sampling and analysis protocols for the full study.
For the multi-element analysis, concentrations of lead, as well as of aluminum, barium, cadmium, calcium, chromium, magnesium, nickel, potassium, titanium, and zinc in dust and soil samples were measured. Concentrations of barium, cadmium, chromium, were abated by primarily the same method on the interior as the exterior (one titanium, and zinc were measured because these elements were regarded as possible constituents of paint. Concentrations of aluminum, calcium, magnesium, nickel, and potassium were measured because these elements were regarded as likely to be found in soil.
The multi-element analysis was undertaken to determine whether relationships among these elements could provide a "tracer" for identifying the sources and pathways of lead in households. Pilot study data were used to 1) characterize the concentrations of lead, aluminum, barium, cadmium, calcium, chromium, magnesium, nickel, potassium, titanium, and zinc samples in household dust and soil; 2) measure the differences in these concentrations associated with renovation and lead-based paint abatement; and 3) investigate the relationship among the elements by sample type (i.e., samples taken from different locations).
Dust and soil samples from six houses in Denver, Colorado were studied. Two houses were unabated (identified as relatively free of lead-based paint in Volume 1 of the CAP Pilot report (US EPA, 1995)). These houses were labeled as "relatively free of lead-based paint" because the lead loadings in paint usually did not exceed the criterion used to trigger abatement in the HUD Abatement Demonstration. The remaining four houses were abated using removal methods and/or encapsulation or enclosure methods. One house was abated using primarily removal methods on the interior and primarily encapsulation or enclosure methods on the exterior. Another house was abated using predominantly encapsulation or enclosure methods on the interior and predominantly removal methods on the exterior. The other two houses removal, the other encapsulation or enclosure). Hence most of the lead levels in the paint in the houses studied were less than 1.0 mg/cm2.
A total of 109 vacuum dust samples was collected. Between 16 and 22 dust samples were collected at each house from window channels (also called "troughs" or "wells"), window stools (often referred to as "sills"), air ducts, floors, bedcovers/rugs/upholstery, and entryways. A total of forty-eight (48) soil samples was collected. Eight samples were collected from each house: from just outside the front and back entryways, at different locations along the foundation, and at different locations on the property boundary.
All elements except for potassium and chromium had significant differences in concentration levels across sample types. Lead, barium, cadmium, calcium, magnesium, nickel, and zinc typically had higher concentration levels in dust samples than in soil samples. Aluminum and titanium generally had higher concentration levels in soil samples than in dust samples. Calcium was the element with the highest concentration in dust samples. Aluminum had the highest concentration in soil samples.
Tests of hypotheses on the differences due to abatement and renovation resulted in far more cases of significance for renovation than for abatement. There were thirteen (13) cases of significant differences for renovation, considerably more than the number of cases that would be expected by chance alone. For renovation effects, there were several cases of significantly higher levels in interior dust for lead and for the elements calcium, magnesium, and nickel. Also for renovation effects, there were cases of significantly lower concentrations in soil sample types for the elements aluminum, titanium, and potassium. For abatement effects, the number of cases of significance was equal to the number that would be expected by chance alone. Significantly higher concentrations of lead and zinc were the case for exterior entryway samples and lead was significantly higher in interior entryway samples.
After controlling for differences between houses with different abatement and renovation history, relative concentrations of the elements suggested the following grouping of sample types in unabated, unrenovated houses: 1) boundary, foundation, and entryway soil samples, and 2) entryway dust and bedcovers/rugs/upholstery, along with floors and window stools. Window channels and air ducts did not appear similar to other sample types or each other. For renovated houses, the three soil samples could be grouped together, and there were similarities between floor and entryway dust samples, and to a lesser extent, between window channels and window stools. For abated houses no groupings were clearly apparent.
Other approaches were used to group sample types. There was no uniformly consistent grouping of sample types, but some sample types were more likely to be clustered together than others. In most groupings, either all three soil samples were in a cluster or two of the soil samples, the foundation and boundary samples, were in a cluster. Typically entryway dust samples and floor dust samples were in the same cluster, sometimes with other sample types as well. Air ducts and bedcovers/rugs/upholstery were the sample types most likely to stand apart from other groups of sample types when grouping approaches were carried out.
There were no definitive identifications of sample types with sources of lead. For example, window channels were observed to contain high concentrations of lead in dust. Some of the analyses in the report indicated that there were high levels of barium and zinc, as well as lead, in the window channel samples. Since barium, zinc, and lead were used in paint, this might indicate paint was the source of the lead. However, aluminum and titanium were also present at high levels in window channel samples, and in this study, these elements appeared to be identified with soil. This would indicate a soil source for the lead. Moreover, titanium was also used in paint. Overall, the analyses in this report did not result in a definitive answer to the source of the lead in the window channels.