REPORT
Draft Final Report
ANALYSIS OF PATHWAYS
OF RESIDENTIAL LEAD
EXPOSURE IN CHILDREN
To
Office of Pollution Prevention and Toxics,
The Environmental Protection Agency
January 24, 1996
OBattelle
. . . Putting Twhnoloxy To Work
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January 24, 1996
DRAFT FINAL REPORT
ANALYSIS OF PATHWAYS OF
RESIDENTIAL LEAD EXPOSURE IN CHILDREN
for
WORK ASSIGNMENT 1-10
SUBTASK 3
Prepared by
Pamela A. Hartford
Nancy J. McMillan
Ronald G. Menton
Jyothi Nagaraja
BATTELLE
505 King Avenue
Columbus, Ohio 43201-2693
John Schwemberger, Work Assignment Manager
Jill Hacker, Project Officer
Contract No. 68-D5-0008
for
Technical Programs Branch
Chemical Management Division
Office of Pollution Prevention and Toxics
U.S. Environmental Protection Agency
Washington, DC 20460
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U.S. EPA DISCLAIMER
This document is a preliminary draft. It has not been released formally by the Office of
Pollution Prevention and Toxics, U.S. Environmental Protection Agency. It is being circulated
for comments on its technical merit and policy implications.
This report was prepared under contract to an agency of the United States Government.
Neither the United States Government nor any of its employees, contractors, subcontractors, or
their employees makes any warranty, expressed or implied, or assumes any legal liability or
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product, or process disclosed in this report, or represents that its use by such third party would
not infringe on privately owned rights.
Publication of the data in this document does not signify that the contents necessarily
reflect the joint or separate views and policies of each sponsoring agency. Mention of trade
names or commercial products does not constitute endorsement or recommendation for use.
BATTELLE DISCLAIMER
This is a report of research performed for the United States Government by Battelle.
Because of the uncertainties inherent in experimental or research work, Battelle assumes no
responsibility or liability for any consequences of use, misuse, inability to use, or reliance upon
the information contained herein, beyond any express obligations embodied in the governing
written agreement between Battelle and the United States Government.
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TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY v
1.0 BACKGROUND 1
2.0 DESCRIPTION OF ENVIRONMENTAL FIELD STUDIES 4
2.1 CAPS 4
2.2 R&M 6
2.3 ROCHESTER 9
3.0 PATHWAYS MODELS 14
3.1 CAPS 14
3.2 R&M 15
3.3 ROCHESTER 16
4.0 RESULTS 17
4.1 CAPS 17
4.2 R&M 18
4.3 ROCHESTER 19
5.0 DISCUSSION 23
REFERENCES 25
LIST OF APPENDICES
APPENDIX A Results from the Pathways Analyses of the CAPS Data A-1
APPENDIX B Results from the Pathways Analyses of the R&M Data B-1
APPENDIX C Results from the Pathways Analyses of the Rochester Data C-1
LIST OF TABLES
Table 1. Description of Variables Used in the CAPS Pathways Analysis 6
Table 2. Description of Variables Used in the R&M Pathways Analysis 8
Table 3. Description of Variables Used in the Rochester Pathways Analysis 12
iii
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LIST OF FIGURES
Figure 1. General Child Blood Lead Pathways Diagram 2
Figure 2. Pathways Diagram Assessing the Role of the Window Well/Window Sill as a
Route From Exterior Dust to Interior Dust 2
Figure 3. Statistically Significant Environmental-Lead Pathways for the CAPS, R&M,
and Rochester Studies 21
Figure 4. Statistically Significant Blood-Lead and Environmental-Lead Pathways for
the R&M and Rochester Studies 22
LIST OF EQUATIONS
Equation Set 1. Equations Comprising the CAPS Environmental-Lead Pathways
Model 14
Equation Set 2. Equations Comprising the R&M Environmental-Lead Pathways
Model 15
Equation Set 3. Equations Comprising the R&M Blood-Lead Pathways Model 15
Equation Set 4. Equations Comprising the Rochester Environmental-Lead
Pathways Model 16
Equation Set 5. Equations Comprising the Rochester Blood-Lead Pathways Model ... 16
IV
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EXECUTIVE SUMMARY
Lead contamination in residential environments has been recognized as a significant
human health problem for a number of years. This problem is most alarmingly manifested in the
elevated blood-lead concentrations of young children. Much of the lead contamination present in
existing residential environments is attributed to sources, such as leaded gasoline and lead-based
paint, which have been eliminated in recent years. Despite reductions in new lead being
introduced into the environment, elevated blood-lead concentrations in children continue to be a
problem due to contamination of the existing environment.
Lead has been found in environmental media such as soil, interior household dust,
exterior dust, and drinking water. Many quantitative exposure models have been proposed in the
scientific literature to describe the pathways by which lead exposure occurs during childhood and
to provide quantitative estimates of the relative contributions of the numerous hypothesized paths
of exposure. Many of these pathways models make use of structural equations to determine both
the direct and indirect effects of lead levels on blood-lead concentrations.
Based on the various pathways models described in the literature, this report develops
pathways models designed to examine the routes by which lead infiltrates the residential
environment and affects childhood blood-lead concentrations. Lead levels in media such as soil,
dust, water, and paint are considered. Dust, measured on a number of surfaces such as window
wells, window sills, interior entryway floors, and floors in general, is also considered. The
pathways models developed are applied to data from existing environmental lead studies.
The data from three environmental-lead field studies, the Comprehensive Abatement
Performance Study (CAPS), Baltimore Repair and Maintenance Study (R&M), and Rochester
Lead-in-Dust Study (Rochester), were utilized in the pathways modeling. Though each study
had similar environmental measures, the study designs varied. The CAPS study was conducted
to evaluate the long-term efficacy of abatement on dust, soil, and painted surfaces. No blood
samples were collected. The R&M study was conducted to compare short-term and long-term
efficacy of comprehensive lead-paint abatement and repair and maintenance interventions for
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reducing lead in settled house dust and children's blood. The Rochester study was a cross-
sectional epidemiological study that evaluated the effect of lead contamination on children's
blood lead. No abatements were performed in this study.
Two sets of pathways models were fitted to each dataset. The first set, the
environmental-lead pathways models, examined the environmental pathways only. These
models were fitted to the CAPS, R&M, and Rochester data separately. The second set, the
blood-lead pathways models, examined the environmental- and blood- lead pathways. These
models were fitted to the R&M and Rochester data separately. Separate models were fit using
the dust-lead loadings and dust-lead concentrations for both the environmental-lead and blood-
lead pathways models.
In the environmental-lead pathways analysis, many consistent pathways were observed
across the three studies. Most notably, the exterior dust to interior entryway dust to floor dust
pathway was statistically significant for all three studies. Another significant pathway was soil
to window well dust to window sill dust. Two of the three studies had a significant pathway
from either window sill or well dust to floor dust based on dust-lead concentrations. For some of
the models fitted to the dust-lead loadings, a similar pathway was observed. In light of the vastly
different backgrounds of the homes chosen for these three studies, the similarities among the
significant pathways of leaded house dust are striking.
Result of the blood-lead pathways models fitted to the R&M and Rochester studies
showed less consistency, possibly because the fitted models were necessarily less similar. One
common thread was that water-lead did not have a significant effect on blood-lead
concentrations. This is not surprising given the overall low levels of water lead in both studies.
Mouthing was an important contributor to childhood blood-lead concentrations in both studies.
The Rochester study provided data to evaluate several pathways that could not be
considered using the data from the other studies. In particular, the effects of carpeted versus
uncarpeted surfaces were assessed. A carpeted interior entryway may lead to higher dust lead
loadings in the interior entryway and on floors in general, but does not necessarily produce
higher blood-lead concentrations. Increasing the proportion of carpeted surfaces in a home
increases the floor and interior entryway dust-lead loadings but decreases the dust-lead
VI
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concentrations. As verified in the data, floor dust-lead loadings, on average, are higher on
carpeted surfaces than on uncarpeted surfaces and vice versa for concentrations. The effect of
the presence of carpet on blood-lead concentrations is more profound. In all cases, increasing the
amount of carpeted surfaces decreases blood lead concentrations.
VII
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1.0 BACKGROUND
"Environmental lead is known to come from multiple sources: drinking water, food, lead-
based paint, emissions from mobile sources, and emissions from industrial sources. Federal and
state regulatory actions have resulted in substantial progress in reducing lead levels in air, food
and paint products. While reductions in air and food have reduced exposures, elevated blood-
lead concentrations in children continue to be a problem due to contamination of the existing
environment. Lead has been found in environmental media such as soil, interior household dust,
exterior dust, and water. Though extensive abatements of paint or soil may reduce the exposure
from one environmental media, it may overlook another important source of lead, failing to halt
childhood lead poisoning cases [1]."
Many quantitative exposure models have been proposed in the scientific literature to
describe the pathways by which residential environmental lead exposure occurs during childhood
and to provide quantitative estimates of the relative contributions of the numerous hypothesized
paths of exposure. These pathways models make use of structural equations to determine both
the direct and indirect effects of lead levels in the residential environment on blood-lead
concentrations. An indirect effect occurs when lead in one residential environmental medium
contaminates another medium, and then lead within the second medium contributes to elevated
blood-lead concentrations. For example, lead in soil tracked into the house increases the lead in
the interior dust. The interior dust lead then contributes to elevated blood-lead concentrations.
Examples of direct effects are the effect of refmishing or child pica habits on the child's blood
lead concentration.
Based on the various pathways models described in the literature, a general pathways
diagram was designed [2]. Figure 1 presents this general pathways diagram. This diagram
incorporates many of the potentially important environmental pathways of residential lead
exposure in children and is the basis from which the pathways examined in this report were
developed. In addition to the pathways illustrated in Figure 1, pathways targeting the role of the
window well/window sill as a possible route from exterior soil/dust to interior dust are presented
in Figure 2.
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Exterior
Paint
Figure 1. General Child Blood Lead Pathways Diagram.
Window Well -
-^Window Sill •
\1
> Floor Dust
t
Figure 2. Pathways Diagram Assessing the Role of the Window Well/Window Sill as a Route From
Exterior Dust to Interior Dust.
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Based on the availability of data, three studies were used to assess the pathways of
residential lead exposure in children. These studies were the Comprehensive Abatement
Performance Study (CAPS), the Baltimore Repair and Maintenance Study (R&M), and the
Rochester Lead-in-Dust Study (Rochester). The pathways models fitted to the data from each
study were designed to be as comparable as possible among the three studies and were analyzed
using PROC CALIS in the SAS® statistical software.
A general description of the goals, study design, and sampling protocols for each of the
three studies is given in Section 2. The construction of environmental lead, housing
characteristic, and child characteristic variables used in subsequent pathways analyses is also
detailed in this section. While the varied sampling protocols among the studies force slightly
different variables for each study, variables have been standardized as much as possible.
Vacuum samples of environmental lead are available for each of the three studies. Variables for
both concentrations and loadings are constructed.
Sections 3 and 4 detail the pathways models fitted to each study and the results from each
model. Each model was fitted to both concentrations and loadings of dust lead variables.
Results are presented in terms of the parameter estimates, associated t-values, and R2 value for
each linear equation in each pathways model. Since the pathways models were fitted to many
log-transformed variables, direct interpretation of model coefficients is difficult. Tables
presenting the effects of increasing one environmental variable 25% above its geometric mean
level while holding all other variables constant are provided to present results in an
understandable, interpretable format. For inter-study comparisons, diagrams of the significant
pathways associated with each model are also presented.
A brief discussion of the similarities and differences among the model results is presented
in Section 5. Additional research, expanding and refining the models already fitted, is also
suggested.
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2.0 DESCRIPTION OF ENVIRONMENTAL FIELD STUDIES
The three environmental-lead field studies examined in this report are described in this
section. Though each study collected similar environmental measures, the study designs varied.
Two of the studies, CAPS and R&M, were abatement studies, seeking to understand the efficacy
of various abatement techniques. The Rochester study was not an abatement study.
CAPS was designed to evaluate the long-term efficacy of abatement on dust, soil, and
painted surfaces. Blood samples were not collected. Environmental lead pathways observed in
CAPS could be affected by the abatements performed.
The R&M study, also an abatement study, took measurements of environmental lead as
well as childhood blood-lead samples both pre-and post-intervention. While only the pre-
intervention measures are included in the pathways analyses, the fact that the abatements were
performed suggests that elevated levels of environmental lead were present. Environmental lead
pathways observed in the R&M study indicate possible pathways for homes with elevated lead
levels that have not been abated.
In contrast, Rochester was a cross-sectional epidemiological study where elevated
environmental lead levels were not the basis for including a home in the study. No abatements
were performed, or a priori, expected to be necessary in Rochester study homes. Environmental
lead pathways observed in the Rochester study are unaffected by abatements and indicative of
possible pathways of lead contamination in homes with lower overall levels of contamination
than observed in the R&M study homes.
Summaries of these three studies are presented in the following subsections, along with
those variables in each study that were used in the pathways analysis.
2.1 CAPS
Environmental lead data were available for 35 homes abated by encapsulation/enclosure
or removal methods in the HUD Abatement Demonstration (HUD Demo) [3], and 17 homes
which were considered for the HUD Demo but were excluded because of low paint lead levels.
All 52 homes were in the Denver, Colorado area. The environmental samples for these homes
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were collected two years after the HUD Demo (i.e., after abatement) took place (abatement
occurred in March and April 1992).
Multiple vacuum dust samples were collected from the supply air ducts, window wells,
window sills, floors (kitchen, bedroom, living room, etc.), inside entryway, and outside
entryway. Soil core samples were collected from the entryway adjacent to the home, the
foundation of the home, and the boundary of the property. The lead in the dust samples were
reported both as loadings (ng/ft2) and concentrations (ng/g) while the lead from the soil samples
were reported as concentrations (ng/g). Additional sampling protocol details are available in [4].
Table 1 provides a description of each of the variables included in the pathways analysis
on the CAPS data. Note that no blood-lead concentrations were available from the CAPS;
therefore, the pathways analysis performed on CAPS data addressed only the pathways among
environmental media.
Table A-l in Appendix A provides the sample size, geometric mean (GM), geometric
standard deviation (GSD), minimum and maximum dust lead loading and dust and soil lead
concentration for the variables used in the analyses. Table A-2 provides geometric mean dust
lead and soil lead levels for abated and unabated homes. The CAPS study report noted that the
air duct-lead and soil-lead levels were higher in abated homes compared to the homes not abated.
Table A-3a displays the Pearson correlations between log transformed dust-lead loadings
and soil-lead concentrations, and Table A-3b presents correlations for the log transformed dust-
and soil-lead concentrations. The most significant correlations in both tables occurred among the
three soil-lead concentrations: exterior entryway, foundation, and boundary of the property.
Other correlated dust-lead variables were the window well and window sill and the interior and
exterior entryway. Because of the high correlation seen among the soil samples, a principal
components analysis of the three log transformed soil lead concentrations was performed to
represent the information from the soil samples within a single linear combination. Over seventy
percent of the variability in the soil samples was explained by the first principal component
(Table A-4) which weighted each soil sample nearly equally. Therefore, a mass-weighted
average soil-lead concentration (i.e. mass-weighted average of exterior entryway, foundation, and
boundary soil-lead concentrations) was used in the analysis.
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Table 1. Description of Variables Used in the CAPS Pathways Analysis.
Analysis Variable
Description
Dust"1
Floor
Interior Entryway
Air Duct
Window Sill
Window Well
Exterior Entryway
Composite of dust collected from the perimeter of uncarpeted floors in the kitchen,
bedroom, living room, etc. (Two rooms were chosen within each home).
Composite
home.
Composite
sampling.
of dust collected immediately inside the front and rear entryways of the
of dust collected from the air ducts in the two rooms chosen for
Composite of dust collected from the window sills in the two rooms chosen for
sampling. Window sill is defined as the horizontal board inside the window which
extends into the house interior.
Composite of dust collected from the window wells in the two rooms chosen for
sampling. Window well is defined as the surface below the window sash and
inside the screen and/or storm window.
Composite
the home.
of dust collected immediately outside the front and rear entryways of
Soil""
Exterior Entrance
Foundation
Boundary
Composite
Composite
Composite
of soil collected immediately outside of the front and rear entryways.
of soil collected at the foundation of the home.
of soil collected at the property boundary
Note: All dust-lead loadings are area-weighted averages in A/g/ft2 and dust-lead concentrations are mass-
weighted averages in fjg/g.
'" Samples were collected using a cyclone vacuum. Floor and entrance samples were collected from
1- ft2 sample areas. Other samples were collected from the entire accessible surface.
"" Composite of three samples collected with a 1 -inch internal diameter plastic butyrate liner and a 12-
inch stainless steel core sampler at 0.5 inch depth
2.2 R&M
The purpose of the R&M study was to compare short-term (2 to 6 months) and long-term
(12 to 24 months) efficacy of comprehensive lead-paint abatement and repair and maintenance
interventions for reducing lead in settled house dust and children's blood. For the homes
included in the study, environmental- and blood-lead samples were collected pre- and post-
intervention.
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The pathways analysis was conducted on all occupied study homes. These homes included
modern urban controls, previously abated controls, and homes from all three repair and
maintenance groups. Eighty-four homes had sufficient data to be included in the pathways
analysis. The modern urban control homes were selected from an urban renewal area. The
previously abated control homes were chosen from a group of 90 low-income housing units
abated between May 1988 and April 1992 in Baltimore City. The repair and maintenance
intervention homes were older, low-income rental properties in Baltimore City and owned by
City Homes and State Realty. By study design, the R&M intervention homes were required to
be structurally sound, not excessively furnished, 800 to 1200 square feet in size, and containing
either lead-based paint (^ 0.7mg Pb/cm2 or z 0.5 percent Pb by weight) on at least one surface in
a minimum of two rooms or be built prior to 1940. Environmental-lead samples were collected
between January 1993 and November 1994.
In many of the 84 homes, multiple children had blood samples taken. For the pathways
analysis, only the blood-lead sample of the youngest child in each home was considered.
Venous blood-lead samples were collected at Kennedy Krieger Research Institute Lead
Clinic by a pediatric phlebotomist using 3 mL vacutainers. The settled house dust samples were
collected using a modified high volume cyclone sampler (R&M cyclone). Three composite floor
dust samples - one across rooms with windows on the first story, one across rooms with
windows on the second story, and one from first and second story rooms without windows -
were collected for each home. Composite window sill and window well samples were collected
separately from all first and second story windows. Settled dust was also collected as individual
samples from the interior entryway and exterior entryway. Drinking water samples were
collected as 2-hour fixed-time stagnation samples from the kitchen faucet - the cold water was
run for at least two minutes to flush the pipes, then a sample from the first flush after a stagnation
period of two hours was collected. Additional details regarding the sampling protocol are
available in [5].
Table 2 provides descriptions of the variables used in the R&M pathways analysis. Table
B-l in Appendix B provides the sample size, geometric mean (GM), geometric standard
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Table 2. Description of Variables Used in the R&M Pathways Analysis.
Analysis Variable
Blood
Description
Venous blood sample collected from children with an average age of 2.21
years (6 months to 4.8 years).
Dust"1
Floor
Interior Entryway
Dust
Exterior Entryway
Dust
Window Sill
Window Well
Composite of dust collected from perimeter of first and second story rooms
with and without windows.
Individual sample collected from the interior entryway of the home.
Individual sample collected from the interior entryway of the home.
Composite of samples collected from the first and second story window
sills.
Composite of samples collected from the first and second story window
wells.
Categorical
Water
Mouthing
R&R Exposure
Collected from kitchen faucet as a 2-hour fixed-time stagnation sample
Categorical variable:
0-LOD (0.6//g/L)
1 - >LOD and < 2.6/yg/L (upper 90%)
2 - > 2.6/yg/L (upper 90%)
Composite of child's mouthing behaviors as indicated during initial the
interview.
Categorical variable:
0 - Child infrequently puts fingers, toys, or paint into mouth (s 1
day/week)
1 - Child frequently puts fingers, toys, or paint into mouth (z 1
day/week)
Composite of R&R activity indicated during initial interview
Categorical variable:
0 - No renovation or remodeling occurred in the 6 months previous to
the interview
1 - Renovation or remodeling occurred within the 6 months previous
to the interview
Note: All dust lead loadings are area-weighted averages in /sg/ft2 and dust lead concentrations are mass-
weighted averages m/sg/g.
"" Samples collected using the R&M cyclone vacuum.
deviation (GSD), and minimum and maximum for the dust-lead loadings, and the blood-, water-,
and dust-lead concentrations. Since very little soil-lead data were available, soil results were not
included in the pathways analysis. The exterior entryway dust lead levels were used as a
surrogate for soil-lead concentrations in some cases. The air duct dust levels also were not
included because very few samples were taken. Table B-2 provides a summary of three
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categorical variables used in the analysis: water lead levels, mouthing behavior, and indicator of
recent renovation and remodeling (R&R) activities.
Tables B-3a and B-3b display the Pearson correlations between the log transformed dust-
lead loadings (ug/ft2), blood-lead (ng/dL) concentrations, and water-lead (ug/L) concentrations
and between the log transformed dust-lead concentrations (|ig/g), blood-lead concentrations
(ng/dL), and water-lead concentrations (ug/L), respectively. In both tables, the most significant
correlations occur between the window well and window sill dust-lead levels. Additionally,
significant correlation is seen between the window sill and floor dust-lead levels and the window
well and floor dust-lead concentrations. The blood-lead concentrations appear to be moderately
correlated with all environmental measures except water-lead. Twenty percent of the water-lead
samples were at or below the limit of detection (0.6 ng/dL).
2.3 ROCHESTER
The Rochester Lead-in-Dust Study was designed to address three objectives: (1) determine
the relation of lead loading and lead concentration of house dust with blood-lead concentrations
among urban children, (2) develop a predictive model relating blood-lead concentrations to lead
levels in house dust, and (3) determine optimal sampling methods to maximize the correlation
between children's blood-lead concentrations and dust lead levels on both carpeted and non-
carpeted surfaces.
Enrollment of 205 children and data collection for all study children and homes were
performed between August and November, 1993. Children 12 to 30 months of age at the time of
enrollment who lived in the city of Rochester and had no known history of elevated blood-lead
concentrations were eligible for the study. Additional eligibility criteria were applied to control
for the possibility of non-residential, non-typical sources of lead affecting blood-lead
concentrations. Complete information regarding sampling techniques for environmental and
blood lead measures as well as details on demographic information and child characteristics
collected in the study are available in the Rochester Lead-in-Dust final report [6].
Venous blood samples were obtained by a certified pediatric phlebotomist during a home
visit using lead-free containers provided by the New York State Department of Health Clinical
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Laboratory Evaluation Program. Three dust collection methods were used to sample settled
house dust. To aid in inter-study comparisons, samples collected using the Baltimore Repair and
Maintenance vacuum method [5], were used in the pathways analyses. Dust samples were
collected from the window well, interior window sill, and floor in the child's bedroom; the
window well and floor in the kitchen; the window well, interior window sill, and floor in the
child's principal play area; the interior window sill and floor in the living room; the interior
entry way floor; and the exterior porch floor. Floor samples were collected over a 1-ft2 area.
Window well and interior window sill samples were collected over one-third of the available
surface area. Soil core samples, taken at a depth of '/2 inch, were collected in two distinct areas:
the perimeter of the foundation and the child's principal outside play area. Because of significant
missing data, only the foundation soil samples were used in the pathways analyses. Three core
soil samples were taken on each side of the house around the perimeter of the foundation where
bare soil was present and combined for a composite foundation sample. The composite soil
sample was sieved into coarse and fine fractions; each fraction was analyzed separately. Two
water samples were taken at each home. One sample was a first draw after an at least 8-hour
stagnation period. The other was collected after a one minute flush. Three XRF paint
measurements were taken from areas such as the window well, sill, and sash, the floor, and the
door in the kitchen, the child's bedroom, the principal play area, the entryway, the living room,
and any deteriorated surface, and the three measurements on each surface were averaged. A
visual inspection of each surface was also performed, and the paint condition rated (l:Poor;
2:Average, or 3:Good).
Eight environmental lead measures, two child characteristic variables, and two housing
characteristic variables were selected for the pathways analyses. The housing characteristic
variables were introduced into the model to account for the floor dust sampling protocol. Floor
dust lead measurements were taken in several rooms; some rooms were carpeted, and some were
not. Preliminary investigation and intuition suggested that measures of floor dust lead on
carpeted and non-carpeted surfaces may represent different measures of a child's lead exposure
via floor dust. Therefore, the pathways analysis had to take into account whether floor dust data
represented samples from carpeted surfaces.
10
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Two floor dust lead variables were included in the pathways model: interior entry way
(Interior Entryway Dust) and composite floor dust from interior rooms (Floor Dust). The interior
entryway was either a carpeted or an uncarpeted room. An indicator variable was included in the
model to differentiate carpeted and uncarpeted interior entryways (Indicator Interior Entryway
Carpet). Floor dust measurements of all other sampled interior rooms were composited to create
Floor Dust. Because floor samples were collected from both carpeted and uncarpeted surfaces,
two intermediate measures were created: The weighted average over all carpeted rooms and the
weighted average over all uncarpeted rooms. Area weighted averages were used for loadings;
mass weighted averages were used for concentrations. Uncarpeted and carpeted floor dust
variables were then combined according to the proportion of carpeted rooms sampled (Proportion
Carpet). Proportion Carpet was also used as a variable in the pathways model.
Variables for window sill dust (Window Sill), window well dust (Window Well), and
exterior dust (Exterior Dust) were also used in the analyses. These variables were constructed as
area/mass weighted averages. For instance if window sill dust measurements were taken in five
rooms, Window Sill was computed as the area/mass weighted average of these five
measurements. Two interior paint measures were used: doors/door jambs XRF hazard score
(Door Paint) and window sills/wells/sashes XRF hazard score (Window Paint). These hazard
scores were calculated as the arithmetic average of the product of XRF paint measurements and
paint quality ratings.
The remaining two environmental measures considered in the pathways analyses were
foundation soil (Soil) and water (Water ND). Many homes in the Rochester study had water-lead
concentrations below the limit of detection. For this reason, an analysis variable was constructed
indicating whether the lead measurement of the one minute flushed water sample was above or
below the detection limit.
Two non-environmental variables utilized were blood lead concentration (Blood) and
extent of pica (Mouthing). Mouthing was constructed from responses to four questions regarding
the mouthing behavior of the child.
All of the environmental variables, excluding the indicator of non-detectable water lead, as
well as blood lead concentration were log transformed for the pathways analyses. Table 3
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Table 3. Description of Variables Used in the Rochester Pathways Analysis.
Analysis Variable
Description
Child Characteristics
Blood
Mouthing
Venous blood sample
Composite of child's mouthing behaviors as indicated by responses to four
mouthing questions at initial interview. Range 0-1 6. Increasing value
indicates increasing tendency to mouth window sill or put thumb, paint chips,
or dirt in mouth.
Dust1"
Exterior Dust
Floor Dust
Interior Entryway
Dust
Window Sill
Window Well
Average of driveway and porch floor dust samples
Composite of the averages of carpeted and uncarpeted interior floors,
excluding the interior entryway
Single measurement of floor dust in the interior entryway
Average of interior window sill dust measurements from all rooms in which
window sills were sampled
Average of window well dust measurements from all rooms in which window
wells were sampled
Soil""
Soil
Geometric mean of coarse and fine foundation soil samples
Other Environmental Media1'1
Window Paint
Door Paint
Water ND
Arithmetic average of the product of XRF paint measurements and paint
quality ratings from window sills, wells, and sashes.
Arithmetic average of the product of XRF paint measurements and paint
quality ratings from interior doors and jambs
One-minute flush water sample.
Categorical Variable:
0: Water lead measurement > 0.0005 mg/L
1 : Water lead measurement £ 0.0005 mg/L
Carpet Variables
Indicator Interior
Entryway Carpet
Proportion Carpet
Indicator of the floor surface type in the interior entryway.
Categorical Variable:
0: Uncarpeted
1 : Carpeted
Proportion of the sampled rooms which were carpeted
Note:
(a)
Ibl
All dust-lead loadings are area-weighted averages in A/g/ft2 and dust-lead concentrations are mass-
weighted averages in //g/g.
Samples collected from 1-ft2 area using the Baltimore Repair and Maintenance vacuum method.
Composite of up to 12 samples taken at a depth of 0.5 inch sieved into coarse and fine fractions for
analysis.
Paint quality ratings were 1:Poor, 2:Average, 3:Good.
12
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provides descriptions of the variables used in the Rochester pathways analyses. Tables C-l and
C-2 in Appendix C provide the sample sizes and descriptive statistics for all variables used in the
analyses. Tables C-3a and C-3b display the correlations among the log-transformed
environmental variables, blood-lead concentrations, Mouthing variable, and Proportion Carpet
variable. Table C-3a displays correlations based on lead loadings; Table C-3b displays those
based on lead concentrations.
13
-------
3.0 PATHWAYS MODELS
As no blood data were collected in CAPS, pathways models fitted to the CAPS data
included only environmental variables. To facilitate comparisons among the three studies,
simple, environmental pathways models were fitted to the data from the R&M and Rochester
studies as well. A second set of models including a blood-lead pathway was created for the
R&M and Rochester studies. Models in each set were constructed to be as similar as possible for
comparison, while still including the most relevant data collected in each study.
The equations representing each structural equation model are presented in a simplified
format for clarity. The coefficients estimated for each variable are not shown in the equations,
and all the environmental and blood lead variables, described as log-transformed in Section 2, are
implicitly assumed to be log-transformed in these equations.
3.1 CAPS
The following four equations represent the environmental pathways model fitted to the
CAPS data.
Floor =
Interior Entryway Dust =
Window Sill
Window Well
Interior Entryway Dust
+ Soil + Air Duct
Exterior Entryway Dust
+ Soil 4- Air Duct
Window Well + Soil
Soil
+ Window Sill + Window Well
+ Window Sill + Window Well
Equation Set 1. Equations Comprising the CAPS Environmental-Lead Pathways Model
These pathways were chosen to facilitate comparison among the Rochester and R&M
environmental pathways analyses. Although air duct dust samples were not available in either
Rochester or R&M datasets, the pathway was included for the CAPS. Recall from Section 2.1
14
-------
that the Soil variable is the mass-weighted average of soil-lead concentration in samples from
three areas (exterior entryway, foundation, boundary).
3.2 R&M
The environmental pathways addressed by the R&M data are presented in Equation Set 2.
Though intended to address the same pathways as the CAPS Model, the R&M and CAPS
environmental pathways models do differ. Because of lack of data, soil-lead and air duct dust-
lead were not examined. Exterior entryway dust was included in the equation to predict floor
dust-lead levels as a surrogate for soil lead concentrations.
Floor
Interior Entryway Dust + Exterior Entryway Dust +
Window Sill + Window Well
Interior Entryway Dust = Exterior Entryway Dust + Window Sill + Window Well
Window Sill
Window Well
Equation Set 2. Equations Comprising the R&M Environmental-Lead Pathways Model
The child blood-lead pathways model fitted to the R&M data is presented in Equation
Set 3. This model was developed to assess the effects of environmental measures on childhood
blood-lead concentrations. In addition to the environmental measures of floor, interior
entryway, exterior entryway, window sill, and window well dust lead, the model included water
lead, R&R exposure, and a mouthing indicator variable.
Blood =
Floor =
Interior Entryway Dust =
Window Sill
Floor + Interior Entryway Dust + Exterior Entryway
Dust -t- Window Sill + Window Well + Water + R&R
Exposure + Mouthing
Interior Entryway Dust + Exterior Entryway Dust +
Window Sill + Window Well + R&R Exposure
Exterior Entryway Dust + Window Sill + Window Well
+ R&R Exposure
Window Well
Equation Set 3. Equations Comprising the R&M Blood-Lead Pathways Model
15
-------
3.3 ROCHESTER
Two pathways models were fitted to the Rochester data. The first model, presented in
Equation Set 4, was designed to investigate the environmental pathways and to allow for
comparison with the results of pathways considered in Equation Sets 1 and 2.
Floor Oust =
Interior Entryway Dust =
Window Sill
Window Well
Indicator Interior Entryway Carpet
Interior Entryway Dust + Exterior
+ Window Well
Indicator Interior Entryway Carpet
Window Sill + Window Well
Window Well + Soil
Soil
+ Proportion Carpet +
Dust + Soil + Window Sill
+ Exterior Dust + Soil +
Equation Set 4. Equations Comprising the Rochester Environmental-Lead Pathways Model
The second pathways model fitted to the Rochester data, displayed in Equation Set 5, includes
the pathways from environmental-lead to childhood blood-lead as well as the contributions of
paint, water, and pica tendencies.
Blood =
Floor Dust =
Interior Entryway Dust =
Window Sill
Window Well
Indicator Interior Entryway Carpet + Proportion Carpet +
Interior Entryway Dust + Floor Dust + Exterior Dust +
Window Sill + Window Well + Window Paint + Door Paint
+ Water ND + Mouthing
Indicator Interior Entryway Carpet + Proportion Carpet +
Interior Entryway Dust + Exterior Dust + Soil + Window
Sill + Window Well + Window Paint + Door Paint
Indicator Interior Entryway Carpet + Exterior Dust + Soil +
Window Sill + Window Well + Window Paint + Door Paint
Window Well + Soil + Window Paint
Soil + Window Paint
Equation Set 5. Equations Comprising the Rochester Blood-Lead Pathways Model
16
-------
4.0 RESULTS
4.1 CAPS
Because there were abated and unabated homes in the CAPS data, an initial analysis was
conducted to examine the relationship between the pre-abatement XRF measurements and dust-
lead loading and concentration on floors and in supply air ducts and foundation soil-lead
concentration taken two years post-abatement. This analysis indicated that the higher XRF
readings in the abated homes were not significantly related to the floor dust-lead levels seen in
the home post-abatement. Therefore, the pathway from paint lead may have been interrupted by
abatement. There was some indication that the higher XRF readings were associated with
higher supply air duct dust-lead concentrations and that the unabated homes had somewhat
lower foundation soil-lead concentrations than the abated homes. These differences may be
related to the dust generated by the abatements. Differences in lead concentrations could also
be related to the fact that the abated homes were on average 17 years older than the unabated
homes.
Because of missing samples, data for only 48 homes were included in the analysis.
Concurrent analyses were performed on the dust-lead loadings and concentrations. Figure 3
illustrates pathways found to be statistically significant (at the 0.05 level); Tables A-5a and
A-5b display the parameter estimates for the models fitted to loadings and concentrations,
respectively. All significant estimates were positive, indicating a positive relationship with the
dependent variable.
Since the models were fitted to log-transformed lead loadings and concentrations, direct
interpretation of the estimated parameters is difficult. Tables A-6a and A-6b provide the
predicted percent increase in dust-lead loadings and concentrations, respectively, (i.e. increase
or decrease from the geometric mean) when one environmental measure (i.e., dust-lead levels at
the interior entrance, window sill, window well, air duct, and exterior entrance, and soil lead
concentrations) is increased by 25% and all other measures remain at their respective geometric
mean. For example, the predicted percent increase in floor dust-lead loadings was between 1%
and 9%, with the largest increase occurring when the soil-lead concentration was increased by
17
-------
25%. Similarly, the predicted percent increase in floor dust-lead concentration was between -
4% and 9%. Again, the maximum increase occurred when soil-lead concentrations were
increased. Increases in the air duct dust levels had very little effect on the floor lead loadings or
concentrations (1% and 3% increase, respectively). Besides floors, the effects of increases in
the environmental measures on dust-lead loadings and concentrations for interior entryways,
window wells, and window sills, are also provided in Tables A-6a and A-6b.
4.2 R&M
Concurrent analyses were performed on the dust-lead loadings and concentrations.
Figure 3 presents the significant pathways found in the environmental-lead models, and Figure 4
illustrates the significant pathways noted for the blood-lead models. Parameter estimates are
presented in Tables B-4a (environmental model using dust-lead loadings), B-4b (environmental
model using dust-lead concentrations), B-5a (blood model using dust-lead loadings), and B-5b
(blood model using dust-lead concentrations).
Models were fitted on log-transformed lead loadings and concentrations making direct
interpretation of the parameter estimates difficult. For interpretation, Tables B-6a and B-6b
present the predicted percentage increase or decrease in environmental-lead variables estimated
by the environmental pathways models when the geometric mean of one environmental
variables is increased by 25%. The predicted percent increases in floor dust-lead loadings and
concentrations were between 2% and 7% and 2% and 11%, respectively. The largest increase,
for both loadings and concentrations, occurred when the window well dust-lead loading was
increased by 25%. The effects on the interior entryway and window sill lead levels are also
provided in Tables B-6a and B-6b.
Tables B-7a and B-7b present the predicted increases in blood-lead, and floor, interior
entryway, and window sill dust-lead levels for the blood-lead pathways model. The predicted
percent increase in blood-lead concentrations ranged from 1% to 3% and 2% to 4% for an
increase in floor, interior entryway, exterior entryway, window sill, and window well dust-lead
loadings and concentrations, respectively. The increase in floor dust-lead loading and interior
entryway dust-lead concentration produced the largest increases in blood-lead concentrations
18
-------
(3% and 4% respectively). When the categorical variables were increased from Little/No
Exposure conditions to Exposure conditions, the predicted percent increase in the blood-lead
concentrations ranged from -6% to 38% and -9% to 31% for the dust-lead loading and dust-lead
concentration models, respectively.
4.3 ROCHESTER
The environmental model was fitted to Rochester study data from 104 and 106 homes for
concentrations and loadings, respectively. The blood lead pathways model utilized the data
from 94 and 97 homes, respectively. Tables C-4a and C-4b in Appendix C display the
parameter estimates from fitting the environmental pathways model. Tables C-5a and C-5b
display the parameter estimates from fitting the blood lead pathways model.
Figures 3 and 4 present the significant pathways detected in each model based on both
concentrations and loadings. The effect of Indicator Interior Entry way Carpet on Interior
Entry way Dust and on childhood blood-lead concentration is of particular interest. A carpeted
interior entryway may lead to higher dust lead loadings in the interior entryway and on floors in
general, but does not necessarily produce higher blood-lead concentrations.
The estimated effect of lead-based paint on windows was expected, providing a
significant pathway for accumulation of leaded dust on window surfaces. The direct effect of
paint lead on doors and jambs on blood lead concentrations in the blood lead pathways model
for concentrations is, however, surprising. This suggests direct ingestion of leaded door and
jamb paint rather than ingestion via house dust.
Tables C-6a, C-6b, C-7a and C-7b show the effect of increasing one environmental
variable at a time 25% above its geometric mean while holding all other variables constant at
their geometric means; Indicator and other variables which were not log transformed were held
constant at their arithmetic means. The percent increases induced by varying child and housing
characteristic variables and the indicator variable for water lead are also presented in this table.
These variables were increased from a level intended to represent low exposure to a level
intended to represent high exposure. For example, mouthing was increased from a score of
four, a level indicating the child never or rarely eats dirt, sucks his fingers or thumb, eats paint
19
-------
chips, or puts his mouth on a window sill, to a score of 11, a level indicating the child regularly
does many of these activities.
For the environmental pathways model, Tables C-6a and C-6b show 2% to 8% and 0% to
11% increases in floor dust lead resulting from the 25% increases in the other environmental
variables for loadings and concentrations, respectively. The impact of increasing the Proportion
Carpet and Indicator Interior Entryway Carpet on floor dust lead is intriguing. Increases in the
proportion of carpeted surfaces in a home are associated with increased floor and interior
entry way dust lead loadings but decreased concentration. As verified in the data, floor dust lead
loadings, on average, are higher on carpeted surfaces than on uncarpeted surfaces and vice versa
for concentrations. This result corroborates the usefulness of interior entryway mats for
reducing soil tracked in to the household.
For the blood lead pathways model, Tables C-7a and C-7b show -1% to 3% increases in
blood lead concentrations resulting from 25% increases in the other environmental variables for
both loadings and concentrations. One percent to 5% and -3% to 12% increases were observed
for floor dust lead levels for loadings and concentrations, respectively. An increase in the
mouthing variable score from 4 to 11 is associated with increased blood lead levels using either
concentrations or loadings. The carpeting variables have effects similar to those observed in the
environmental pathways model for floor dust lead for both loadings and concentrations. The
effect of the carpeting variables on blood lead levels is more profound. In all cases, increasing
carpeted surfaces is associated with decreases in blood lead concentrations.
20
-------
Dust-Lead Loadings (M9/ft )
CAPS
(a) Soil • Window Well »• Window Sill
(b) Interior Entryway Dust »- Floor
RAM
Window
Well
Rochester
Window
Sill
Exterior Entryway
Dust
Interior
Entryway
Dust
Floor
Soil
Window
.Well
Exterior Dust
Indicator Interior
Entryway Carpet
f Window
Sill
Interior Entryway Dust »• Floor Dust
Dust-Lead Concentrations (iig/g)
CAPS
(a) Soil »- Window Well —»• Floor
1
Window SHI
(b) Exterior Entryway Dust » Interior Entryway Dust
R&M
Window
Well '
Window
Sill
Exterior Entryway Dust
I
Interior Entryway Dust
Floor
Rochester
Soil
Window
Well
Exterior Dust '
Window
Sill
Interior Entryway
Floor Dust
Floor Dust
Figure 3. Statistically Significant Environmental-Lead Pathways for the CAPS, R&M, and Rochester Studies.
-------
Dust-Lead Loadings (ug/ft )
Dust-Lead Concentrations (ug/g)
R&M
Window
Well "
Window
SMI
Exterior Entryway
Dust
Interior
Entryway
Dust
Floor
Mouthing
Blood
Rochester
Exterior Dust -
Soil
Window
" Well ~
Indicator Interior.
Entryway Carpet
I
Interior Entryway-
Dust
t
Door Paint
Window
' Sill
Floor Dust ,
Blood
\ t
Mouthing
Window Paint
R&M
Window
Well "
Window
Sill
Exterior Entryway
Dust
Interior
Entryway
Dust
Floor
Blood
Rochester
Indicator Interior.
Entryway Carpet
Exterior Dust
Soil.
Figure 4. Statistically Significant Blood-Lead and Environmental-Lead Pathways for the R&M and Rochester Studies.
-------
5.0 DISCUSSION
In the environmental-lead pathways analysis, many consistent pathways were observed
across the three studies. Notably, the role of exterior dust to interior entry way dust to floor dust
was important. Another significant pathway was soil dust to window well dust to window sill
dust. Two of the three studies had a significant pathway from either window sill or well to floor
dust based on dust-lead concentrations. A similar pathway was observed for the models fitted to
the dust loadings. In light of the vastly different backgrounds of the homes chosen for these
three studies (CAPS included homes abated two years prior to environmental sampling, R&M
included homes slated to be abated, and Rochester included homes not suspected of needing
abatement), the similarities among the significant pathways of leaded house dust are striking.
The result from the blood lead pathways models fitted to the R&M and Rochester studies
showed less consistency, possibly because the fitted models were necessarily less similar. One
common thread was that water lead did not have a significant effect on blood lead
concentrations. This is not surprising given the overall low levels of water lead in both studies.
Mouthing was an important contributor to childhood blood-lead concentrations in both studies.
However, the next draft of this report will code this variable consistently for both studies to
facilitate comparisons. One disturbing feature is that floor-lead concentrations did not appear to
directly affect blood-lead levels, while floor-lead loadings did. The effects of lead-based paint
cannot be compared across these studies as measurements were not available in the R&M study.
The presence of dust samples from carpeted surfaces in the Rochester study allowed for
an investigation of the effect of carpeted surfaces on floor and blood-lead levels in the pathways
analysis. The presence of interior entryway carpeting was significantly associated with
decreased blood-lead concentration and increased floor lead-loadings. The impact of carpeting
on the results of the pathways analysis suggests a need for deeper investigation of the carpeting
effect.
The unfortunate attrition of homes in the Rochester dataset, due to missing data, is a
problem that will be somewhat alleviated in the next draft of this report. Some of the homes
23
-------
excluded on the basis of Floor Dust were considered missing because no carpeted floors were
sampled. Careful coding of the Floor Dust and Proportion Carpet variables will allow using
only the uncarpeted floor measurements for these homes.
24
-------
REFERENCES
[1] Menton, Ronald G., David A. Burgoon, and Allan H. Marcus, "Pathways of Lead
Contamination for the Brigham and Women's Hospital Longitudinal Lead Study" in
Beard, Michael E. and S.D. Allen Iske, ed., Lead in Paint. Soil, and Dust: Health Risks.
Exposure Studies. Control Measures. Measurement Methods, and Quality Assurance, and
STP; 1226,1993 ASTM Boulder Conference on Lead in Paint, Soil, and Dust.
[2] Hartford, Pam, Priti Kumar, and Ron Menton, "Analysis Plan for Work Assignment 5-03,
Subtask 3, Pathways Analysis," May 3, 1995.
[3] Office of Policy Development and Research, U.S. Department of Housing and Urban
Development, "The HUD Lead-Based Paint Abatement Demonstration (FHA)," HUD-
1316-PDR, August 1991.
[4] Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency, Final
Report for the Comprehensive Abatement Performance Study Volume I: Summary
Report, EPA 230-R-94-013a, March 1995.
[5] Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency,
Amendment to (Revision No. 3) Quality Assurance Project Plan (QAPjP) for Efficacy of
Repair and Maintenance Interventions, December 14,1992.
[6] The University of Rochester School of Medicine and The National Center for Lead-Safe
Housing, (1995). "The Relation of Land-Contaminated House Dust and Blood Lead
Levels Among Urban Children," Departments of Pediatrics, Biostatistics, and
Environmental Medicine, Final Report, Volume 2, June 1995.
25
-------
APPENDIX A
Results from the Pathways
Analyses of the CAPS Data
A-l
-------
Table A-1. Summary Statistics for the Lead Loadings (//g/ft2) and Concentrations U/g/g)
Included in the CAPS Pathways Analyses.
Location of
Sample
Dust
Floor
Interior Entrance
Air Duct
Window Sill
Window Well
Exterior Entrance
Soil
Exterior Entrance
Foundation
Boundary
N
52
52
52
52
49
51
52
52
52
Loadings dig/ft2)
Geometric
Mean (GSD)*
Minimum -
Maximum
Concentrations (figlg)
Geometric
Mean (GSD)*
Minimum -
Maximum
48.8(5.01)
342 (4.57)
156(8.16)
107(6.81)
3,230 (6.32)
574 (4.00)
2.02 - 2,636
1.66-4,870
4.13-25,400
2.76- 16.700
45.0 - 93,500
17.2- 10,700
174(2.91)
201(2.44)
485 (2.23)
778 (4.08)
1,577(4.65)
261 (2.68)
157 (2.24)
196(2.52)
132 (1.94)
37.9 - 5420
9.65 - 4,940
122-2,920
45.8- 17,000
133-22,900
20.7 - 2,820
19.7-644
11.0- 1810
24.1 - 606
GSD = Geometric standard deviation.
Table A-2. Geometric Mean Lead Loadings (//g/ft2) and Concentrations (//g/g) for
Abated and Unabated Homes Included in the CAPS Pathways Analyses.
Location of
Sample
Loadings (//g/ft2)
Unabated Homes*
(N = 17)
Abated Homes*
(N = 35)
Concentrations (jig/g)
Unabated Homes*
(N = 17)
Dust
Floor
Interior Entrance
Air Duct
Window Sill
Window Well
Exterior Entrance
42.3 (6.24)
200 (7.40)
58.3 (7.24)
52.7 (5.14)
2,600 (6.46)
351 (4.43)
52.4 (4.55)
444 (3.22)
252 (7.48)
152 (7.17)
3,588 (6.38)
718 (3.67)
143(2.66)
164(2.25)
449 (2.38)
487 (3.95)
1,050(4.15)
204 (2.67)
Abated Homes*
(N = 35)
192 (3.03)
222 (2.52)
503(2.18)
977 (3.99)
1,923 (4.82)
292 (2.66)
Soil
Exterior Entrance
Foundation
Boundary
122 (2.47)
107 (2.43)
99.1 (2.06)
177 (2.09)
263 (2.22)
151 (1.82)
Geometric standard deviation is given in parentheses.
A-2
-------
Table A-3a. Correlations for Log-Transformed Dust-Lead Loadings (/ig/ft2) and Soil-Lead Concentrations (//g/g)
Used in the CAPS Pathways Analysis.
Floor Dust
Air Duct Dust
Interior
Entryway Dust
Window
Well Dust
Window
Sill Dust
Exterior
Entryway Dust
Exterior
Entryway Soil
Foundation
Soil
Boundary
Soil
Floor
Dust
1.00000
52
0.15743
52
0.35648
52
0.10123
49
0.21698
52
0.18105
51
0.20107
52
0.06759
52
0.23057
52
Air
Duct
Dust
0.15743
52
1.00000
52
0.05862
52
0.13728
49
0.11246
52
0.24169
51
0.14830
52
0.05701
52
0.20016
52
Interior
Entryway
Dust
0.3564B
52
0.05862
52
1.00000
52
0.19758
49
0.32992
52
0.22004
51
0.28452
52
0.13223
52
0.18554
52
Window
Well
Dust
0.10123
49
0.13728
49
0.19758
49
1.00000
49
0.55256
49
0.02957
48
0.2B873
49
0.15568
49
0.25439
49
Window
Well
Dust
0.21698
52
0.11246
52
0.32992
52
0.55256
49
1.00000
52
0.00309
51
0.22846
52
0.12126
52
0.29352
52
Exterior
Entryway
Dust
0.18105
51
0.24169
51
0.22004
51
0.02957
48
0.00309
51
1.00000
51
0.19018
51
0.18760
51
-0.02470
51
Exterior
Entryway
Soil
0.20107
52
0.14830
52
0.28452
52
0.28873
49
0.22846
52
0.19018
51
1.00000
52
0.52970
52
0.64037
52
Foundation
Soil
0.06759
52
0.05701
52
0.13223
52
0.15568
49
0.12126
52
0.18760
51
0.52970
52
1.00000
52
0.55853
52
Boundary
Soil
0.23057
52
0.20016
52
0.18554
52
0.25439
49
0.29352
52
-0.02470
51
0.64037
52
0.55853
52
1.00000
52
Note:
1. Correlations were conducted on the natural logarithm transformed dust-lead loadings and soil-lead concentrations.
2. First number is the Pearson correlation coefficient, and the second number is the number of observations.
-------
Table A-3b. Correlations for Log-Transformed Dust-Lead Concentrations (//g/g) and Soil-Lead Concentrations (//g/g)
Used in the CAPS Pathways Analysis
Floor Dust
Air Duct Dust
Interior
Entryway Dust
Window
Well Dust
Window
Sill Dust
Exterior
Entryway Dust
Exterior
Entryway Soil
Foundation
Soil
Boundary
Soil
Floor
Dust
1.00000
52
0.14612
52
0.22249
52
0.28349
49
0.01190
52
0.09858
51
0.19160
52
0.13421
52
0.33594
52
Air
Duct
Dust
0.14612
52
1.00000
52
0.19240
52
0.17034
49
0.20521
52
0.05998
51
0.18726
52
-0.01820
52
0.18599
52
Interior
Entryway
Dust
0.22249
52
0.19240
52
1.00000
52
0.14587
49
0.00561
52
0.55763
51
0.37130
52
0.17489
52
0.23164
52
Window
Well
Dust
0.28349
49
0.17034
49
0.14587
49
1.00000
49
0.59493
49
0.11442
48
0.39132
49
0.14883
49
0.30910
49
Window
Well
Dust
0.01190
52
0.20521
52
0.00561
52
0.59493
49
1.00000
52
-0.04710
51
0.24320
52
0.08412
52
0.23619
52
Exterior
Entryway
Dust
0.09858
51
0.05998
51
0.55763
51
0.11442
48
-0.04710
51
1.00000
51
0.31996
51
0.18571
51
0.03995
51
Exterior
Entryway
Soil
0.19160
52
0.18726
52
0.37130
52
0.39132
49
0.24320
52
0.31996
51
1.00000
52
0.52970
52
0.64037
52
Foundation
Soil
0.13421
52
-0.01820
52
0.17489
52
0.14883
49
0.08412
52
0.18571
51
0.52970
52
1.00000
52
0.55853
52
Boundary
Soil
0.33594
52
0.18599
52
0.23164
52
0.30910
49
0.23619
52
0.03995
51
0.64037
52
0.55853
52
1.00000
52
Note: 1. Correlations were conducted on the natural logarithm transformed dust-lead loadings and soil-lead
concentrations.
2. First number is the Pearson correlation coefficient, and the second number is the number of observations.
-------
Table A-4. Principal Components Analysis of the Entryway, Foundation, and Boundary
Soil-Lead Concentrations (//g/g) from the CAPS Study.
Simple Statistics
Mean
StD
WCBDY
4.881270657
0.664755800
WCFDN
5.278522566
0.923506587
WCEWY
5.053991088
0.806544484
WCBDY
WCFDN
WCEWY
Correlation Matrix
WCBDY WCFDN
1.0000
0.5585
0.6404
0.5585
1.0000
0.5297
WCEWY
0.6404
0.5297
1.0000
PRIN1
PR1N2
PRIN3
Eigenvalues of the Correlation Matrix
Eigenvalue Difference Proportion
2.15371
0.48896
0.35733
1.66475
0.13162
0.717903
0.162986
0.119111
Cumulative
0.71790
0.88089
1.00000
WCBDY
WCFDN
WCEWY
Eigenvectors
PRIN1 PRIN2
0.592676
0.554944
0.583757
-.297676
0.824371
-.481457
PRIN3
-.748415
0.111578
0.653778
WCBDY = Mass-weighted boundary soil concentration
WCFDN = Mass-weighted foundation soil concentration
WCEWY = Mass-weighted exterior entryway soil concentration
A-5
-------
Table A-5a. Structural Equation Modeling Results for the CAPS Environmental Pathways
- Dust-Lead Loadings (//g/ft2).
Variables
"N. Independent
Dependent \,
Floor
Interior Entryway
Dust
Window Sill
Window Well
Interior
Entryway
Dust
0.3184*
(2.10)
Direct Effect Parameter Estimates (t-value)
Window
Sill
0.1320
(0.92)
0.2424
(1.86)
Window
Well
-0.0632
(-0.44)
-0.0097
(-0.07)
0.5291*
(4.06)
Exterior
Entryway
Dust
0.2294
(1.49)
Air Duct
0.0516
(0.47)
-0.045
(-0.42)
Soil
0.1328
(0.38)
0.3491
(1.07)
0.4513
(1.29)
0.8059*
(2.15)
R2
0.1562
0.1912
0.3318
0.0899
Note: 1. Bolded and a * indicate parameter estimates are significant at the 0.05 level. T-values > 2.0 and < -2.0 are
significant at the 0.05 level.
2. Pathways analyses were conducted on the natural logarithm transformed dust-lead loadings and soil-lead
concentrations.
3. First number is estimated parameter; second number is corresponding t-value.
Table A-5b. Structural Equation Modeling Results for the CAPS Environmental Pathways
- Dust-Lead Concentrations (//g/g).
Variables
\v Independent
Dependent N»
Floor
Interior Entryway
Dust
Window Sill
Window Well
Direct Effect Parameter Estimates (t-value)
Interior
Entryway
Dust
0.1669
(0.98)
Window
Sill
-0.1868
(-1.50)
-0.0167
(-0.18)
Window
Well
0.2598*
(2.14)
0.0176
(0.20)
0.5389*
(4.56)
Exterior
Entryway
Dust
0.4531*
(4.09)
Air Duct
0.1010
(0.552)
0.1352*
(1.02)
Soil
0.1557
(0.66)
0.1964
(1.14)
0.0810
(0.31)
0.8479*
(2.81)
R2
0.1630
0.3480
0.3531
0.1436
Note: 1. Bolded and a * indicate parameter estimates are significant at the 0.05 level. T-values > 2.0 and < -2.0 are
significant at the 0.05 level.
2. Pathways analyses were conducted on the natural logarithm transformed dust-lead loadings and soil-lead
concentrations.
3. First number is estimated parameter; second number is corresponding t-value.
A-6
-------
Table A-6a. Predicted Effect of a 25% Increase in Environmental-Lead Loadings (//g/ft2)
Based on the CAPS Dust-Lead Loadings (//g/ft2) Structural Equation Model
Sample Location
Interior Entryway
Window Sill
Window Well
Air Duct
Soil""
Exterior Entryway
Dust-Lead Loading
Geometric
Mean
l/ig/ft2)
340
108
3,229
156
179
572
25% Increase
inGM
(/ig/ft2)
425
135
4,037
195
224
716
Predicted Percent Increase in
Dust-Lead Loadings
Floor
7%
5%
1%
1%
9%
2%
Interior
Entryway
(b)
6%
3%
-1%
13%
5%
Window
Sill
(c)
(c)
13%
Ic)
22%
(c)
Window
Well
Id)
Id)
Id)
Id)
20%
Id)
'" Average soil-lead concentration in //g/g.
"" The fitted pathway model did not include a pathway from the sample to Interior Entryways.
"' The fitted pathway model did not include a pathway from the sample to Window Sills.
"" The fitted pathway model did not include a pathway from the sample to Window Wells.
Table A-6b. Predicted Effect of a 25% Increase in Environmental-Lead Concentrations
(//g/g) Based on the CAPS Dust-Lead Concentrations (//g/g) Structural
Equation Model
Sample Location
Interior Entryway
Window Sill
Window Well
Air Duct
Soil""
Exterior Entryway
Dust-Lead Concentration
Geometric
Mean (//g/g)
201
778
1.577
485
179
261
25% Increase
inGM
(pg/g)
252
973
1,972
606
224
326
Predicted Percent Increase in
Dust-Lead Concentration
Floor
4%
-4%
4%
3%
7%
2%
Interior
Entryway
(U
0%
0%
3%
5%
11%
Window
Sill
Ic)
(c)
13%
(c)
13%
(c)
Window
Well
Id)
Id)
Id)
Id)
21%
(d)
"' Average soil-lead concentration in A
-------
APPENDIX B
Results from the Pathways
Analyses of the R&M Data
B-l
-------
Table B-1. Summary Statistics for the R&M Variables Included in the Pathways
Analyses.
Location of
Sample
N
Loadings fcig/ft2)
Geometric Mean
(GSD}*
Minimum - Maximum
Concentrations (/ig/g)
Geometric Mean
(GSD)*
Minimum - Maximum
Dust Levels
Floor
Interior Entryway
Oust
Exterior Entryway
Dust
Window Sill
Window Well
84
84
84
84
84
213 ( 5.58)
317(8.45)
419(9.37)
1,254(18.11)
40,366 (20.50)
2.09- 24,725
3.47- 26,417
7.25- 196,752
2.04- 1,215,321
36.2 -2,496,630
1,149(4.41)
1,474(4.56)
1,581 (5.24)
5,809 (8.57)
9,064 ( 7.10)
40.4-64,109
39.8 - 42,625
17.6-89,505
7.25- 141,057
108-191,480
Other Levels
Blood
Water
84
84
8.48 (2.04)
2.20 (3.93)
1.15-42
0.15-29.7
*GSD = Geometric standard deviation
Table B-2. Summary of the Categorical Variables Included in the R&M Pathways
Analyses.
Indicator
Variable
Water-Lead
Level
Mouthing
Behavior
R&R Exposure
Indicator
Levels
0.00
1
2
0.00
1
0.00
1
Description
£ LOO (0.6 //g/L)
> LOD and s 2/6 //g/L
> 2.6ug/L
Infrequent fingers, toys, and paint chips
in mouth
Frequent (a 1 day/week) of fingers,
toys, or paint chips in mouth
No renovation or remodeling occurred in
6 months previous to interview
Remodeling or renovation occurred 6
months previous to interview
%of
Population
20
69
11
82
18
90
10
B-2
-------
Table B-3a. Correlation of Log-Transformed Blood-Lead Concentrations 1/sg/dL), Dust-Lead Loadings (//g/ft2), and
Water-Lead Concentrations (/ig/L).
Blood
Floor Dust
Interior Entryway Dust
Window Hell Dust
Window Sill Dust
Exterior Entryway Dust
Water
Blood
1.00000
0.51075
0.38403
0.45307
0.44451
0.38458
0.09405
Floor
Dust
0.
1.
0.
0.
0.
0.
-0.
51075
00000
49194
58614
63400
37981
09084
Interior
Entryway
Dust
0.
0.
1.
0.
0.
0.
0.
38403
49194
00000
32833
47581
41380
01681
Window
Well
Dust
0
0
0
1
0
0
0
.45307
.58614
.32833
.00000
.83776
.37988
.04843
Window
Sill
Dust
0
0
0
0
1
0
0
.44451
.63400
.47581
.83776
.00000
.48748
.09035
Exterior
Entryway
Dust
0
0
0
0
0
1
-0
.38458
.37981
.41380
.37988
.48748
.00000
.05991
Water
-0.09405
-0.09084
0.01681
0.04843
0.09035
-0.05991
1.00000
Note: 1. Correlations were conducted on the natural logarithm transformed dust-lead loadings and blood-, soil- and water-lead
concentrations.
2. Numbers presented are Pearson correlation coefficients. Sample size is 84 for all correlations.
-------
Table B-3b. Correlation of Log-Transformed Blood-Lead (//g/dL), Dust-Lead (//g/g), and Water-Lead (//g/L)
Concentrations.
00
Blood
Floor Dust
Interior Entryway Dust
Window Hell Dust
Window Sill Dust
Exterior Entryway Dust
Hater
1
0
0
0
0
0
0
Blood
.00000
.52404
.54616
.43583
.50553
.49685
.09405
0
1
0
0
0
0
0
Floor
Dust
.52404
.00000
.59771
.68791
.74943
.58973
.01334
Interior
Entryway
Dust
0.54616
0.59771
1.00000
0.52323
0.65894
0.76111
0.01871
0
0
0
1
0
0
0
Window
Well
Dust
.43583
.68791
.52323
.00000
.82665
.59699
.00020
Window
Sill
Dust
0
0
0
0
1
0
0
.50553
.74943
.65894
.82665
.00000
.73126
.05885
Exterior
Entryway
Dust
0.49685
0.58973
0.76111
0.59699
0.73126
1.00000
0.09440
-0
0
0
0
0
0
1
Water
.09405
.01334
.01871
.00020
.05885
.09440
.00000
Note: 1. Correlations were conducted on the natural logarithm transformed dust, blood-, soil-, and water-lead
concentrations.
2. Numbers presented are Pearson correlation coefficients. Sample size is 84 for all correlations.
-------
Table B-4a. Structural Equation Modeling Results for the R&M Environmental Pathways
Models - Dust-Lead Loadings (//g/ft2).
Variables
\v Independent
Dependent \
Floor
Interior Entryway
Window Sill
Direct Effects Parameter Estimates (t-value)
Interior
Entryway
0.2088*
(2.74)
Window Sill
0.1675
(1.82)
0.3998*
(3.19)
Window Well
0.1420
(1.64)
-0.1510
(-1 .23)
0.8034*
(13.98)
Exterior
Entryway
0.0310
(0.45)
0.2200*
(2.30)
R*
0.46
0.25
0.70
Note: 1. Bolded and a * indicate parameter estimates are significant at the 0.05 level. T-values > 2.0 and < -2.0 are
significant at the 0.05 level.
2. Pathways analyses conducted on the natural log-transformed dust-lead loadings and soil-lead concentrations.
Table B-4b. Structural Equation Modeling Results for the R&M Environmental Pathways
Models - Dust-Lead Concentrations 2.0 and < -2.0 are
significant at the 0.05 level.
2. Pathways analyses were conducted on the natural log-transformed dust- and soil-lead concentrations.
B-5
-------
Table B-5a. Structural Equation Modeling Results for the R&M Blood Lead Pathways
Models - Dust-Lead Loadings (//g/ft2).
Variables
N. Independent
Dependent >v
Blood
Floor
Interior Entryway
Window Sill
Floor
0.1225*
(2.44)
Direct Effects Parameter Estimates (t-value)
Interior
Entryway
0.0480
(1.33)
0.2195*
(2.93)
Exterior
Entryway
0.0386
(1.22)
0.0268
(0.40)
0.221 !•
(2.31)
Window Sill
-0.0261
(-0.62)
0.1951*
(2.17)
0.3811*
(3.05)
Window
Well
0.0675
(1.71)
0.0973
(1.14)
-0.1239
(-1 .00)
0.8034*
(13.98)
Water
-0.0618
(-0.55)
R&R
Exposure
-0.0104
(-0.05)
0.8742
(1.84)
-0.5122
(-0.74)
Mouthing
0.3243*
(2.00)
R2
0.37
0.49
0.25
0.70
Note: 1. Bolded and a * indicate parameter estimates are significant at the 0.05 level. T-value > 2.0 or < -2.0
significant at 0.05 level.
2. Pathways analyses were conducted on the natural log-transformed blood-lead and dust-lead loadings and
blood-lead concentrations.
Table B-5b. Structural Equation Modeling Results for the R&M Blood Lead Pathways
Models - Dust-Lead Concentrations (//g/g).
Variables
N. Independent
Dependent N^
Blood
Floor
Interior Entryway
Window Sill
Direct Effects Parameter Estimates (t-value)
Floor
0.1059
(1.65)
Interior
Entryway
0.1468*
(2.27)
0.2185*
(2.03)
Exterior
Entryway
0.0379
(0.65)
-0.0128
(-0.13)
0.5302*
(6.45)
Window Sill
0.0381
(0.69)
0.3222*
(3.71)
0.1739*
(2.02)
Window
Well
-0.0243
(-0.39)
0.1258
(1.20)
-0.0035
(-0.03)
0.9059*
(13.38)
Water
-0.0969
(-0.89)
R&R
Exposure
0.2856
(1.26)
0.4953
(1.30)
-0.3877
(-1.00)
Mouthing
0.2545
(1.62)
R2
0.39
0.60
0.58
0.68
Note: 1. Bolded and a * indicate parameter estimates are significant at the 0.05 level. T-value > 2.0 or < -2.0
significant at 0.05 level.
2. Pathways analyses were conducted on the natural log-transformed dust-lead and blood-lead concentrations.
B-6
-------
Table B-6a. Predicted Effect of a 25% Increase in Environmental-Lead Loadings (//g/ft2)
Based on the R&M Dust-Lead Loadings (//g/ft2) Structural Equation Model.
Sample Location
Interior Entryway
Exterior Entryway
Window Sill
Window Well
Dust-Lead Loading
Geometric
Mean (jig/ft2)
317
419
1,254
40,366
25% Increase
inGM
-------
Table B-7a. Predicted Effect of 25% Increase in Environmental-Lead Loadings (//g/ft2) on
the Blood-Lead Concentrations (//g/dL) and Dust-Lead Loadings (//g/ft2) Based
on the R&M Dust-Lead Loadings (/ig/ft2) Structural Equation Model.
Sample Location
Floor
Interior Entry way
Exterior Entry
Window Sill
Window Well
Water""
R&R Exposure""
Mouthing""
Dust-Lead Loading
Geometric Mean
(//g/ft2)
213
317
419
1,254
40,366
Little/No Exposure
1
0
0
25% Increase
in GM (/ig/ft2)
267
396
524
1,568
50,458
Exposure
2
1
1
Predicted Percent Increase in
Dust-Lead Loadings
Blood
3%
2%
1%
1%
2%
Floor
(a)
5%
2%
6%
7%
Interior
Entryway
(b)
(b)
5%
9%
4%
Window
Sill
Id
(c)
(c)
(c)
20%
-6%
6%
38%
lit
114%
la)
(b)
-40%
(bl
Id
1C)
(c)
'" The fitted pathway model did not include a pathway from the sample location to Floor.
"" The fitted pathway model did not include a pathway from the sample location to Interior Entryway
"' The fitted pathway model did not include a pathway from the sample location to Window Sill.
"" Variables were treated as categorical.
Table B-7b. Predicted Effect of 25% Increase in Environmental-Lead Concentrations
(//g/g) on the Blood-Lead and Dust-Lead Concentrations (//g/ft2) Based on the
R&M Dust-Lead Concentrations (//g/g) Structural Equation Model.
Sample Location
Floor
Interior Entryway
Exterior Entry
Window Sill
Window Well
Water""
R&R Exposure""
Mouthing""
Dust-Lead Concentration
Geometric Mean
(//g/g)
1,149
1,474
1,581
5,809
9,064
Little/No Exposure
1
0
0
25% Increase
inGM
(//g/g)
1,437
1,843
1,976
7,261
11,330
Exposure
2
1
1
Predicted Percent Increase in
Dust-Lead Concentration
Blood
2%
4%
3%
2%
2%
Floor
la)
5%
2%
8%
11%
Interior
Entryway
Ib)
Ib)
13%
4%
3%
Window
Sill
1C)
1C)
1C)
1C)
22%
-9%
31%
29%
la)
51%
la)
Ib)
-32%
Ib)
(c)
1C)
1C)
'" The fitted pathway model did not include a pathway from the sample location to Floor.
"" The fitted pathway model did not include a pathway from the sample location to Interior Entryway
lcl The fitted pathway model did not include a pathway from the sample location to Window Sill.
"" Variables were treated as categorical.
B-8
-------
APPENDIX C
Results from the Pathways
Analyses of the Rochester Data
c-i
-------
Table C-1. Summary Statistics for the Rochester Variables Included in the Pathways
Analyses.
Location of Sample
N
Loadings (/ig/ft2)
Geometric
Mean (GSD)*
Minimum -
Maximum
Dust Levels
Exterior Dust
Floor Dust
Interior Entryway
Dust
Window Sill
Window Well
164
166
177
197
189
515.34(7.34)
100.10(4.34)
88.62 (13.51)
345.07 (10.45)
22583.58(21.58)
0.08-51012.00
3.49-37093.30
0.30-32040.00
0.68-117821.10
6.86-3030213.88
N
172
162
174
199
188
Concentrations U/g/g)
Geometric Mean
(GSD)*
Minimum -
Maximum
655.69 (5.35)
562.89 (4.05)
467.77 (4.90)
2787.03 (8.44)
8675.53 (10.72)
0.16-44854.13
21.88-57345.59
1 .62-20784.97
3.15-368111.11
5.15-207180.87
Other Levels
Blood
Soil
Window Paint
Door Paint
Proportion Carpet
Mouthing
N
205
203
Arithmetic
Mean (SD)
0.38
2.67
Minimum -
Maximum
0-1
0-11
205
187
199
196
6.38 (1.85)
Oug/dL)
851.87 (3.83)
(^g/g)
4.86(4.12)
1.51 (3.68)
1.4-31.70
19.75-27142.50
0.5-73.33
0.5-52.87
GSD = Geometric standard deviation.
Table C-2. Summary of Categorical Variables Included in the Rochester Pathways
Analysis.
Indicator Variable
Water ND
Indicator Interior
Entryway Carpet
Levels
0
1
0
1
Description
Water lead measurement > 0.0005 mg/L
Water lead measurement s 0.0005 mg/L
Uncarpeted Interior Entryway
Carpeted Interior Entryway
%of
Population
27%
73%
64%
36%
C-2
-------
Table C-3a. Correlation of Log-Transformed Blood-Lead Concentrations (fjgldL), Dust-Lead Loadings (//g/ft2),
Soil-Lead Concentrations (/sg/g), and Child and Housing Characteristic Variables.
Blood
Floor Dust
Interior Entryway Dust
Window Sill
Window Well
Exterior Dust
Mouthing
Proportion Carpet
Soil
Blood
1.00000
205
0.38380
166
0.15113
m
0.34288
191
0.37431
189
0.10605
164
0.11669
203
0.22194
205
0.36924
181
Floor
Dust
0.38380
166
1.00000
166
0.31311
146
0.38909
163
0.28183
155
0.19953
134
-0.00035
164
0.04440
166
0.22333
153
Interior
Entryway
Dust
0.15113
117
0.31317
146
1.00000
177
0.22144
172
0.21090
164
0.21526
144
-0.00115
175
-0.00978
177
0.33916
161
Window
Sill
0.34288
197
0.38909
163
0.22144
172
1.00000
197
0.55848
184
0.24033
160
-0.05224
195
-0.08404
197
0.37066
181
Window
Well
0.37437
189
0.28783
155
0.21090
164
0.55848
184
1.00000
189
0.22711
151
-0.05682
181
-0.13024
1B9
0.44630
174
Exterior
Dust
0.10605
164
0.19953
134
0.21526
144
0.24033
160
0.22711
151
1.00000
164
-0.04903
162
-0.14239
164
0.21506
152
Mouthing
0.11669
203
-0.00035
164
-0.00775
175
-0.05224
195
-0.05682
187
-0.04903
162
1.00000
203
0.11707
203
0.12261
185
Proportion
Carpeted
-0.22194
205
0.04440
166
-0.00978
177
-0.08404
197
-0.13024
189
-0.14239
164
0.11707
203
1.00000
205
-0.09477
187
Soil
0.36924
187
0.22333
153
0.33916
161
0.37066
181
0.44630
174
0.21506
152
0.12261
185
-0.09477
187
1.00000
187
Note:
1. Analyses were conducted on natural logarithm transformed blood-lead and soil-lead concentrations and dust lead loadings.
2. First number Is the Pearson correlation coefficient, and the second number is the number of observations.
-------
Table C-3b. Correlation of Log-Transformed Blood-Lead (//g/dL), Dust-Lead (//g/g), and Soil-Lead (//g/g)
Concentrations, and Child and Housing Characteristic Variables.
o
Blood
Floor Oust
Interior Entryway Dust
Window Sill
Window Well
Exterior Dust
Mouthing
Proportion Carpet
Soil
Blood
1.00000
205
0.15036
162
0.08323
174
0.23639
199
0.21112
188
0 11436
P2
0.11669
203
0.22194
205
0.36924
187
Floor
Dust
0.15036
162
1.00000
162
0.35955
139
0.35195
160
0.19303
150
0.13817
136
-0.03915
160
-0.00180
162
0.06773
149
Interior
Entryway
Dust
0.08323
174
0.35955
139
1.00000
174
0.24679
170
0.23814
160
0.23838
148
-0.02824
172
-0.08393
174
0.24524
159
Window
Sill
0.23639
199
0.35195
160
0.24679
no
1.00000
199
0.55223
183
0.27469
168
-0.11125
197
-0.03245
199
0.33537
182
Window
Well
0.21112
188
0.19303
150
0.23814
160
0.55223
183
1.00000
188
0.21672
158
-0.08497
186
-0.00234
188
0.49852
173
Exterior
Dust
0.11436
172
0.13811
136
0.23838
148
0.27469
168
0.21672
158
1.00000
172
-0.07690
170
-0.15739
172
0.28968
160
Mouthing
0.11669
203
-0.03915
160
-0.02824
172
-0.11125
197
-0.08497
186
-0.07690
no
1.00000
203
0.11707
203
0.12261
185
Proportion
Carpeted
-0.22194
205
-0.00180
162
-0.08393
174
-0.03245
199
-0.00234
188
-0.15739
172
0.11707
203
1.00000
205
-0.09477
187
Soil
0.36924
187
0.06773
149
0.24524
159
0.33537
182
0.49852
173
0.28968
160
0.12261
185
-0.09477
187
1.00000
187
Note:
1. Analyses were conducted on natural logarithm transformed blood-lead, dust-lead, and soil-lead concentrations.
2. First number is the Pearson correlation coefficient, and the second number is the number of observations.
-------
Table C-4a. Structural Equation Modeling Results for the Rochester Environmental
Pathways Models - Dust-Lead Loadings (//g/ft2).
Variables
x. Independent
Dependent >^
Floor
Interior
Entryway Dust
Window Sill
Window Well
Direct Effect Parameter Estimates (t-value)
Indicator Interior
Entryway
Carpet
-0.4935
(-1.5379)
3.3808*
(9.5175)
Proportion
Carpet
0.7018
(0.7448)
Interior
Entryway
Dust
0.2350*
(3.5356)
Exterior
Dust
0.01430
(0.2464)
0.2286*
(2.8628)
Soil
0.0534
(0.4698)
0.4087*
(2.5417)
0.2461
(1.5959)
1.0813*
(4.9349)
Window
Well
0.0453
(0.9181)
0.0351
(0.4855)
0.3475*
(5.6166)
Window
Sill
0.1074
(1.5763)
0.0161
(0.1605)
R2
0.2294
0.5157
0.3294
0.1883
Note: 1. Bolded and a * indicate aparameter estimates are significant at the 0.05 level. T-value > 2.0 or < -2.0
significant at 0.05 level.
2. Pathways analyses were conducted on the natural logarithm transformed dust-lead loadings and soil-lead
concentrations.
3. First number is estimated parameter; second number is corresponding t-value.
Table C-4b. Structural Equation Modeling Results for the Rochester Environmental
Pathways Models - Dust-Lead Concentrations (//g/g).
Variables
v Independent
Dependent ^S.
Floor
Interior
Entryway Dust
Window Sill
Window Well
Direct Effect Parameter Estimates (t-value)
Indicator Interior
Entryway
Carpet
-0.2904
(-1.3176)
-0.3927
(-1.5445)
Proportion
Carpet
-0.9532
(-1.1490)
Interior
Entryway
Dust
0.4579*
(5.4636)
Exterior
Dust
-0.1106
(-1.6815)
0.2458*
(3.4249)
Soil
-0.1419
(-1.3640)
0.1527
(1.2606)
0.1850
(1.1958)
0.9710*
(6.2887)
Window
Well
-0.1200
(-1.8888)
0.1464
(1.9969)
0.4756*
(5.6677)
Window
Sill
0.2834*
(4.4307)
-0.0239
(-0.3185)
R2
0.3566
0.2268
0.3535
0.2774
Note: 1. Bolded and a * indicate parameter estimates are significant at the 0.05 level. T-value > 2.0 or < -2.0
significant at 0.05 level.
2. Pathways analyses were conducted on the natural logarithm transformed dust-lead and soil-lead concentrations.
3. First number is estimated parameter; second number is corresponding t-value.
C-5
-------
Table C-5a. Structural Equation Modeling Results for the Rochester Blood Lead Pathways
Models - Dust-Lead Loadings (//g/ft2).
Variables
Indopondent
Dflpondont ^*»
Blood
Floor
Interior
Entryway
Dust
Window
Sill
Window
Well
Indicator
Interior
Entryway
Carpet
•0.3777*
(-2.6178)
-0.4092
(-1.1959)
3.3572*
(9.2280)
Proportion
Carpet
•0.5896
(-1.4476)
0.6370
(0.6469)
Direct Effects Parameter Estimates It-value)
Floor
Dust
0.1205*
(2.8231)
Interior
Entryway
Dust
0.0134
(0.4496)
0.2157*
(3.0994)
Exterior
Dust
•0.0461
(-1.8347)
0.0133
(0.2208)
0.2370*
(2.8558)
Soil
0.0470
(0.3545)
0.4719*
(2.5591)
0.0674
(0.3846)
0.5406*
(2.2083)
Window
Wells
0.0780*
(3.4613)
0.0505
(0.9316)
0.0696
(0.8791)
0.2520*
(3.5356)
Window
SHIs
0.0371
(1.2159)
0.0621
(0.8537)
0.0207
(0.1944)
Window
Paint
-0.0472
(-0.9544)
0.0943
(0.7633)
-0.3419
(1 .9365)
0.4829*
(3.1127)
0.8931*
(4.4087)
Door
Paint
0.0703
(1.5385)
0.1446
(1.3404)
0.3344*
(2.1890)
Water ND
-0.0546
(-0.4990)
Mouthing
0.0459*
12.0513)
R1
0.4043
0.2476
0.5385
0.3463
0.2922
Note: 1. Bolded and a * indicate parameter estimates are significant at the 0.05 level. T-value > 2.0 or < -2.0
significant at 0.05 level.
2. Pathways analyses were conducted on the natural logarithm transformed dust-lead loadings, blood-lead and soil-
lead concentrations, and paint hazard scores.
3. First number is estimated parameter; second number is corresponding t-value.
Table C-5b. Structural Equation Modeling Results for the Rochester Blood Lead Pathways
Models - Based on Dust-Lead Concentrations (//g/g).
Variables
Independent
Blood
Floor
Interior
Entryway
Dust
Window
Sill
Window
Well
Direct Effects Parameter Estimates It-value)
Indicator
Interior
Entryway
Carpet
-0.2835*
(-2.3008)
•0.2085
(•0.9017)
-0 4679
(-1 7217)
Proportion
Carpet
•0 8875
(-1 9736)
-1 0992
(-1.3072)
Floor
Dust
0.0090
(0.1651)
|_»__|__
iniBnor
Entry w&y
Dust
-0.0410
(-0.7897)
0.4921*
(5.7561)
Exterior
Dust
-0.0561
(-1 5291)
-0.1666*
(-2.5092)
0.2389*
(3.1808)
Soil
-0.1885
(-1.64361
0.1720
(1.2564)
0.0224
(0.1276)
0.4187*
(2.3953)
Window
Walls
0.0778*
(2.0110)
•0.2074*
(-2 9561)
0.1695*
(2.0363)
0.3646*
13 6084)
Window
Sills
0.0105
(0 2802)
0.2428*
(3.68071
-0.0034
(0 0425)
infindow
Paint
0.0310
(0 5735)
0.2316*
(2.2071)
-0.1688
(-1 .344O)
02849
(1 8519)
0.6062*
(4.1859)
Door
Paint
0.1202*
(2.2473)
0.1637
(1.6763)
0 1501
(1.2852)
Water ND
0.0464
(0.35871
Mouthing
0.0542*
(2.1010)
If
02511
0.4189
02097
02711
0.3028
Note: 1. Bolded and a * indicate parameter estimates are significant at the 0.05 level. T-value > 2.0 or < -2.0
significant at 0.05 level.
2. Pathways analyses were conducted on the natural logarithm transformed dust-lead, blood-lead, and soil-lead
concentrations and paint hazard scores.
3. First number is estimated parameter; second number is corresponding t-value.
C-6
-------
Table C-6a. Predicted Effect of a 25% Increase in Environmental-Lead Loadings (/ig/ft2)
Based on Rochester Dust-Lead Loadings (//g/ft2) Structural Equation Model.
Sample Location
Interior Entryway Dust
Window Sill
Window Well
Soil1"
Exterior Dust
Sample Location
Proportion Carpet
Indicator Interior Entryway
Carpet
Dust-Lead Loading
Geometric
Mean
-------
Table C-7a. Predicted Effect of 25% Increase in Environmental-Lead Loadings (//g/ft2) on
the Blood-Lead Concentrations (/ig/dL) and Dust-Lead Loadings (//g/ft2) Based
on Rochester Dust-Lead Loadings l/ig/ft2) Structural Equation Model.
Sample Location
Floor Dust
Interior Entryway Dust
Window Sill
Window Well
Soil""
Exterior Dust
Window Paint
Door Paint
Proportion Carpet
Indicator Interior
Entryway Carpet
Mouthing
Water ND
Dust-Lead Loading
Geometric
Mean
(pg/g)
100.10
88.62
345.07
22583.58
851.87
515.34
4.86
1.51
Little/No
Exposure
0.80
1
4
1
25%
Increase in
GM
Cvg/g)
125.13
110.78
431.34
28229.48
1064.84
644.18
6.08
1.89
Exposure
0.20
0
11
0
Predicted Percent Increase in
Dust-Lead Loadings
Blood
3%
1%
1%
2%
2%
-1%
1%
2%
Floor
(b)
5%
1%
2%
5%
1%
3%
5%
Interior
Entryway
(c)
(c)
0%
2%
12%
5%
-6%
8%
Window
Sill
(d)
(dl
(d)
6%
5%
(d)
17%
(d)
Window
Well
(a)
(a)
(a)
(a)
13%
(e)
22%
(e)
36%
34%
38%
6%
-32%
-27%
(a)
(a)
(b)
-97%
Ib)
(b)
(c)
(c)
(c)
(c)
(d)
(d)
Id)
Id)
Ib)
(cl
Soil lead is measured as a concentration.
The fitted pathways model does not include a pathway from the sample location to Floor Dust.
The fitted pathways model does not include a pathway from the sample location to Interior Entryway
Dust.
The fitted pathways model does not include a pathway from the sample location to Window Sills.
The fitted pathways model does not include a pathway from the sample location to Window Wells.
C-8
-------
Table C-7b. Predicted Effect of 25% Increase in Environmental-Lead Concentrations
(/ig/g) on the Blood-Lead (/ig/dL) and Dust-Lead U/g/g) Concentrations Based
on Rochester Dust-Lead Concentration (//g/g) Structural Equation Model.
Sample Location
Floor Dust
Interior Entryway Dust
Window Sill
Window Well
Soil
Exterior Dust
Window Paint
Door Paint
Proportion Carpet
Indicator Interior
Entryway Carpet
Mouthing
Water ND
Dust-Lead
Concentration
Geometric
Mean
(//g/a)
562.89
467.77
2787.03
8675.53
851.87
655.69
4.86
1.51
Little/No
Exposure
0.80
1
4
1
25%
Increase in
GM
U/9/9)
703.61
584.71
3483.79
10844.41
1064.84
819.61
6.08
1.89
Exposure
0.20
0
11
0
Predicted Percent Increase in
Dust-Lead Concentration
Blood
0%
-1%
0%
2%
1%
-1%
2%
3%
Floor
(a)
12%
6%
-1%
-3%
-1%
4%
5%
71%
31%
46%
-4%
93%
55%
(a)
la)
Interior
Entryway
(b)
(b)
0%
4%
6%
5%
-2%
3%
(b)
60%
Ib)
Ib)
Window
Sill
(0
(c)
(c)
8%
4%
(c)
12%
(0
Window
Well
(d)
(d)
(d)
Id)
10%
(d)
14%
(d)
(c)
1C)
(c)
(c)
Id)
Id)
Id)
Id)
"' The fitted pathways model does not include a pathway from the sample location to Floor Dust.
"" The fitted pathways model does not include a pathway from the sample location to Interior Entryway Dust.
'" The fitted pathways model does not include a pathway from the sample location to Window Sills.
"" The fitted pathways model does not include a pathway from the sample location to Window Wells.
C-9
------- |