February 1998
EPA 747-R-98-OO13
FINAL REPORT
SOURCES OF LEAD IN SOIL:
A LITERATURE REVIEW
Prepared by
Battelle Memorial Institute
Technical Programs Branch
Chemical Management Division
Office of Pollution Prevention and Toxics
Office of Prevention, Pesticides, and Toxic Substances
U.S. Environmental Protection Agency
Washington, DC 2O46O
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DISCLAIMER
The material in this document has been subject to Agency technical and policy review
and approved for publication as an EPA report. Mention of trade names, products, or services
does not convey, and should not be interpreted as conveying, official EPA approval,
endorsement, or recommendation.
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AUTHORS AND CONTRIBUTORS
This study was funded and managed by the U.S. Environmental Protection Agency. The
review was conducted by Battelle Memorial Institute under contract to the Environmental
Protection Agency. Each organization's responsibilities are listed below.
Battelle Memorial Institute (Battelle)
Battelle was responsible for conducting the literature search, obtaining and reviewing the
identified articles and reports, developing the conclusions and recommendations derived from the
review, and preparing this report.
U.S. Environmental Protection Agency (EPA)
The Environmental Protection Agency was responsible for managing the review,
providing guidance on the objectives for the review and report, contributing to the development
of conclusions and recommendations, and coordinating the EPA and peer reviews of the draft
report. In addition, EPA provided access to study results not yet available in the general
literature. The EPA Work Assignment Managers were Samuel Brown and John Schwemberger;
the EPA Project Officers were Jill Hacker and Sineta Wooten; the EPA Section Chief was Phil
Robinson; and the EPA Branch Chiefs were Cindy Stroup and Brion Cook.
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TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY Mi
1.0 INTRODUCTION AND BACKGROUND 1
1.1 Organization of this Report 2
2.O OBJECTIVES 2
3.0 METHODOLOGY OF LITERATURE REVIEW 3
3.1 Primary Literature Search Methodology 3
3.2 Secondary Literature Search Methodology 4
4.0 RESULTS OF LITERATURE SEARCH 5
4.1 Overview of Results 5
4.2 Source Apportionment Methodology 10
4.3 Lead-Based Paint 12
4.4 Point Source Emitters 22
4.5 Leaded Gasoline Emissions 28
5.0 CONCLUSIONS 35
6.O REFERENCES 38
List of Tables
Table 3-1. Results of Literature Search by Year 4
Table 4-1. Studies Identified in the Literature 8
Table 4-2. Reported Measures of Central Tendency of Soil-lead
Concentrations for Studies Identifying Paint as Responsible
Source 14
Table 4-3. Correlation Results Reported Between Soil-Lead and Exterior
Paint-Lead Variables 2O
Table 4-4. Reported Measures of Central Tendency of Soil-Lead
Concentrations for Studies Identifying Point Source Emitter as
Responsible Source 24
Table 4-5. Reported Measures of Central Tendency of Soil-Lead
Concentrations for Studies Identifying Gasoline Emissions as
Responsible Source 3O
List of Figures
Figure 4-1. Locations of Identified Studies Examining Sources of
Elevated
Soil-Lead Concentrations 6
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TABLE OF CONTENTS
(continued)
Figure 4-2. Locations of Studies Identified as Citing Lead-Based Paint as a
Source of Soil Lead 13
Figure 4-3. Geometric Means for Foundation and Open Samples Reported
in the Minnesota Soil Lead Study 19
Figure 4-4. Geometric Means of Soil-lead Concentrations by Year of Construction, Near and Far
Samples, New Haven, Connecticut Lead Study 21
Figure 4-5. Geometric Means of Soil Lead by Age and Condition of Home,
The Cincinnati Longitudinal Lead Study 22
Figure 4-6. Locations of Studies Identified as Citing a Point Source Emitter
as a Source of Soil Lead 23
Figure 4-7. Geometric Means of Lead Loading for Composite Soil Samples by Distance From
Point Source (miles) 27
Figure 4-8. Locations of Studies Identified as Citing Gasoline Emissions
as a Source of Soil Lead 29
Figure 4-9. Arithmetic Mean Soil-Lead Concentrations for 0-5 cm Samples Collected
8, 25, and 50 Meters from a Roadway, Beltsville Roadway Study 33
Figure 4-10. Arithmetic Means of Soil-Lead Concentrations by Traffic Volume as Reported in
the Illinois Soil Lead Study 34
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EXECUTIVE SUMMARY
Title X of the Housing and Community Development Act, known as the Residential
Lead-Based Paint Hazard Reduction Act of 1992, contains legislation designed to evaluate and
reduce exposures to lead in paint, dust, and soil in the nation's housing. As amended in Title X,
§403 of Title IV of the Toxic Substances Control Act (TSCA), EPA is required to "promulgate
regulations which shall identify, for the purposes of this title and the Residential Lead-Based
Paint Hazards Reduction Act of 1992, lead-based paint hazards, lead-contaminated dust, and
lead-contaminated soil."
Integral to the development of the §403 mandated standards (especially for soil) is
information on the sources, extent, and geographic breadth of elevated lead contamination of soil
("elevated" because lead is naturally present in soil in many geographic regions). Such
information provides perspective when considering what level of lead in soil will be defined as
hazardous, and would suggest the extent of the remediation needed for different §403 standards.
The purpose of the study summarized in this report was to search and review the
scientific literature on the sources of elevated soil-lead concentrations. More importantly, the
study identified the basis upon which elevated soil-lead levels were attributed to a particular
source. Literature searches were conducted to identify relevant articles and were supplemented
by studies previously uncovered by the authors of this report. In all, 36 relevant studies were
identified and formed the basis for this report.
The results of the literature search indicate that studies assessing soil-lead concentrations
and sources have been conducted in a wide variety of communities across the United States. The
scientific literature, however, contains a preponderance of urban and smelter community studies.
Rural studies were relatively rare, their soil-lead levels usually used only as a measure of
background lead when examining results from urban environments.
Consistent with what might be expected, three sources of elevated soil-lead levels were
identified in the literature: (1) lead-based paint; (2) point source emitters; and (3) leaded gasoline
emissions. Eight types of supporting evidence, commonly reported in the literature as
justification for asserting that a particular source contributes to elevated soil-lead levels, were
identified: (1) residential area pattern (i.e., the distribution of soil-lead levels around the
in
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residence); (2) paint-lead loading on exterior walls of residence; (3) age of residence; (4) type
and condition of housing; (5) distance from a hypothesized source of elevated soil-lead levels;
(6) ambient air-lead levels; (7) traffic volume on roadways in the vicinity of areas being
examined; and (8) community area pattern.
The implications of the reviewed information concerning questions of source
apportionment were investigated. No definitive evidence was found within the literature,
however, suggesting a particular source can be regularly identified as responsible for elevated
soil-lead concentrations at a residence. In fact, many studies cite more than one source as
commonly responsible for elevated soil-lead levels. Moreover, labor- and cost-intensive
techniques for carefully apportioning the sources of lead exposure to soil suggest varying relative
contributions from candidate sources. It may be possible on a case-by-case basis to apportion the
responsible sources, but no generalizations are possible based on readily obtained categorical
factors (e.g., urban verus rural, northeast versus southwest). It is worth noting that within the
literature lead-based paint is often cited as the source responsible for higher concentrations of
lead in the surrounding soil; homes with extreme lead levels in their soil were often found to be
coated with lead-based paint.
Although the results of this study suggest that a single source cannot be universally
associated with elevated soil-lead levels, the results do confirm the suspected pairwise
associations between elevated soil-lead levels and lead-based paint, leaded gasoline emissions, or
point source emissions. As such, interventions targeting these sources should prove at least
partially beneficial in reducing lead contamination of soil. In particular, lead-based paint
interventions, such as those prompted by the promulgation of the §403 standards, should have an
additional benefit of removing a source of lead in soil, above and beyond any benefit seen in
reduced indirect exposure to elevated dust-lead levels and direct exposure to paint chips.
IV
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1.0 INTRODUCTION AND BACKGROUND
Lead is not naturally present in the human body and, as it currently exists in the
environment, has been identified as a health threat. In particular, there exists extensive evidence
that even at low dosages, lead may contribute to mental retardation and learning disabilities in
children under the age of seven exposed to lead hazards [jj. As a result, the Centers for Disease
Control and Prevention (CDC) has adopted a lower standard of 10 |ig/dL as the community level
of concern in children. As suggested by various authors, lead may contaminate humans from
various pathways including: inhalation of airborne lead particulates, consumption of water or
food contaminated by lead, and ingestion (due to contamination of hands or other objects) of soil
or dust contaminated with lead [1]. Several studies have indicated that young children have an
increased risk due to their greater propensity for placing non-food objects into their mouths and
the vulnerability of their developing neurological functions.
On October 29, 1992, President George W. Bush signed the Residential Lead-Based Paint
Hazard Reduction Act (Title X of HR 5334). This Act included legislation that requires the U.S.
Environmental Protection Agency (EPA) to define standards for lead in paint, dust, and soil.
More specifically, §403 of Title IV of the Toxic Substances Control Act, as amended in Title X,
requires that EPA "promulgate regulations which shall identify, for the purposes of this title and
the Residential Lead-Based Paint Hazards Reduction Act of 1992, lead-based paint hazards, lead-
contaminated dust, and lead-contaminated soil."
Integral to the development of the §403 mandated standards (especially for soil) is
information on the sources, extent, and geographic breadth of elevated lead contamination of
soil. Such information provides perspective when considering what level of lead in soil will be
defined as hazardous, and is suggestive of the potential efficacy of some interventions prompted
by promulgation of the standards.
Lead is present naturally in soil, though in most regions at relatively low levels. The U.S.
Geological Survey has estimated the concentration of naturally occurring lead in soil to have a
national geometric mean of 16 ppm [2]. There are many sources that may contribute to increased
levels of lead in residential soils including (but not exclusively): peeling, chalking, or active
removal of lead-based paint; fallout from the discharge of community waste incinerators,
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smelters, or foundries; dumping or burning of lead batteries and their casings; and emission
fallout from vehicles fueled with leaded gasoline.
The purpose of the study summarized in this report was to search and review the
scientific literature on the sources of elevated soil-lead concentrations. More specifically, this
report documents an effort to identify in the literature the basis upon which elevated soil-lead
levels were attributed to a particular source, that is, the evidence that was cited as justification for
attributing elevated soil-lead levels to a particular source.
1.1 ORGANIZATION OF THIS REPORT
This report is organized into six chapters. In Chapter 2, the objectives of the task are
presented in greater detail. The methodology employed in the searches is detailed in Chapter 3.
The results of the literature including an in-depth discussion of each source and the types of
evidence used to support the hypothesis that it is responsible for elevated soil-lead levels is
presented in Chapter 4. Conclusions of the study are presented in Chapter 5. The final chapter
contains the citation reference with links to the corresponding study abstract.
2.O OBJECTIVES
The primary objective of this literature review was to acquire a greater understanding of
the sources and associated evidence of lead in contaminated soil through a review of the
scientific literature. One aspect of this objective was to identify commonly cited sources of lead
in soil. Another aspect was to identify the supporting evidence used to justify an assertion that a
particular source contributes to elevated soil-lead levels. As additional objectives, a bibliography
of relevant studies and a summary of each study, in standard format, were developed.
It is important to note that this study was not conducted to estimate national levels of soil-
lead contamination nor to relate soil contamination from a particular source to the manifested
lead exposure observed in resident children. As such, only a subset of all published articles with
documented soil-lead levels were considered (i.e., those articles tracing or addressing the source
responsible for elevated soil-lead levels).
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3.O METHODOLOGY OF LITERATURE REVIEW
Relevant studies were identified either by pre-existing knowledge on the part of the
authors or through literature searches. While the focus of this task was not on exposure studies,
some exposure studies were incidentally identified in the literature searches. Studies were
included in this report if they provided insight into the sources of elevated soil-lead levels.
The review of the scientific literature was conducted by examining a list of articles and
reports identified in several literature searches. The primary literature search focused only on
studies addressing the sources of elevated soil-lead levels and is presented in detail in Section
3.1. In addition to this search, results from prior searches of a somewhat similar nature
conducted on behalf of the EPA were examined. A re-examination of the results of these
searches was conducted to supplement studies identified in the primary search. Literature
relevant to the current issues were identified and included in this report. The methodology and
objectives of the additional literature searches are presented in Section 3.2. In all, 36 studies
were identified using the two search methodologies. These studies form the basis for this report.
3.1 PRIMARY LITERATURE SEARCH METHODOLOGY
The primary literature search concentrated on identifying field studies that examined the
source and the accompanying supporting evidence of elevated soil-lead levels. Twenty-five
public health and environmental databases including NTIS, Federal Register, and Enviroline
were searched for relevant articles.
The search was conducted by selecting keywords, search dates, and abstract keys, and
defining the relationships between them. The search followed a progressively more restrictive
hierarchy to identify relevant journal articles and reports. At each step, the selection criteria were
narrowed until a manageable number of potentially relevant articles were identified.
As an initial starting point, databases were examined for articles with the keyword "soil"
used anywhere in the article. A total of 634,074 articles were found satisfying this criterion.
Searching the same databases for articles mentioning "Lead" or "Pb" reduced the number of
potentially relevant articles to 394,173. To further refine the list of articles a third, more
restrictive selection criterion was imposed. In this third step, the search was restricted to those
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articles with "Lead" or "Pb" and "Soil" in the title. Finally, the list was further refined by
retaining only those articles or reports written in English and by eliminating any redundant
entries. Table 3-1 presents the resulting numbers of identified articles partitioned by year of
publication.
Table 3-1. Results of Literature Search by Year
Breakdown By
Year
1970-1974
1975-1979
198O-1984
1985-1989
1990-1992
Total
Number of
Articles Found
480
888
912
994
515
3789
Number of
Articles (English
only)
325
673
667
776
446
2887
Number of
Unique Articles
(English only)
142
232
248
282
169
1073
In order to have a manageable number of entries to review, only articles written after 1980 were
considered. Due to environmental and exposure pathway changes prompted by regulations in
leaded gasoline and paint, articles published prior to 1980 were less likely to be relevant to
current issues. By limiting the literature search to unique, English only articles published after
1980 with "Lead" or "Pb" and "Soil" in the title, 699 articles were identified as potentially
relevant to this task. The abstracts for these articles were reviewed, and 28 papers were
identified, read, and reviewed. From these, 18 studies were abstracted.
3.2 SECONDARY LITERATURE SEARCHES METHODOLOGY
The secondary approach to identifying relevant studies was to review the results of four
similar, but more general, literature searches previously conducted by the EPA [47 (2 searches),
69, 70]. Each of these literature searches was conducted in a similar manner to that of the
primary literature search. However, the focus of these searches was on field exposure studies
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that measured lead in both multiple environmental media and blood. As such, they involved
more general keywords and broader selection criteria. Additionally, articles were also identified
by reviewing the reference sections of known, relevant articles. In all, over 500 titles, abstracts,
or journal articles were reviewed and 122 possible studies were identified. These studies were
re-examined, and 18 were determined to be pertinent to this study.
4.O RESULTS OF THE LITERATURE SEARCH
This chapter presents the results of the literature search in five sections. First, Section 4.1
presents an overview of the results of the literature search. A summary of the types of supporting
evidence and statistical methodology used to assert that a particular source is responsible for
elevated soil-lead levels is given in Section 4.2. The remaining three sections, 4.3, 4.4, and 4.5,
discuss in detail each identified source and the supporting evidence used to justify the hypothesis
that the source was responsible for elevated soil-lead levels.
4.1 OVERVIEW OF RESULTS
Studies assessing soil-lead concentrations (PbS) and its sources have been conducted in a
wide variety of communities. They range from large urban centers such as Boston,
Massachusetts, to smaller cities like Butte, Montana, to small towns such as Telluride, Colorado.
Studies have been conducted over the entire United States, from Maine to California. The sites
where studies were conducted to assess soil-lead levels are indicated in Figure 4-1. Darkened
circles on the map represent communities where soil-lead concentration has been examined and
documented within the literature.
The literature contains a preponderance of urban and smelter community studies. This
emphasis is likely the result of attempts to target the populations most at risk and examine
communities with extensive environmental lead exposure. Heavily populated urban
environments are commonly contaminated with lead from both leaded gasoline emissions and
lead-based paint. Smelter communities often have widespread lead contamination of their
environmental media. Environmental lead studies in rural communities, on the other hand, are
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rare and are usually only used as a measure of background lead when examining the soil-lead
concentration results from urban environments.
Sssnte
Mmeapdis/StRaul
Portland
Bdtsville
Chafleston
Hrrringharn
Figure 4-1. Locations of Identified Studies Examining Sources of
Elevated Soil-Lead Concentrations.
Three sources of elevated soil-lead levels were identified in the literature. In addition, the
supporting evidence used to assert that a particular source was responsible for elevated soil-lead
levels was identified. The three sources identified were:
! Lead-based paint on exterior surfaces such as the walls of buildings
! Point source emitters such as smelters, batteries, or mine tailings
! Leaded gasoline emissions from automobiles.
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The types of supporting evidence reported in the literature as justification for asserting that a
particular source contributes to elevated soil-lead levels were:
! Residential area pattern, such as the distribution of soil-lead levels around
the residence
i
Paint-lead loading1 on exterior walls of the residence
Age of residence
Type and condition of housing
! Distance from a hypothesized source of elevated soil-lead levels
! Ambient air-lead levels
! Traffic volume on roadways in the vicinity of the area being examined
! Community area pattern, such as highway infrastructure or residential
density of city.
Table 4-1 presents all of the sites identified in the review. For each site, the table
provides: a reference for the study, the year the study was conducted, the total number of soil
samples collected, the range in soil-lead concentrations, the hypothesized sources of the lead, and
the types of supporting evidence cited in determining the lead source. The range is reported since
consistent measures of central tendency were unavailable. For example, one study reports
arithmetic means by type of housing, while another documents geometric means by volume of
traffic on nearby roadways. The table is sorted alphabetically by state and community within
each state.
As an example of the information given in the table, consider the Boston, Massachusetts
entry. From Table 4-1, it can be noted that in this 1981 study, 195 soil samples were collected,
and soil-lead levels were reported to range from 7 to 13,240 ppm. Distance from the source,
paint-lead loading, and traffic volume are cited by the authors as supporting evidence for their
1 Paint-lead loading is defined as the milligrams of lead per unit area sampled, typically reported as mg/ft2
or mg/cm2
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assertion that lead-based paint and leaded gasoline emissions were the sources responsible for the
elevated soil-lead levels.
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Table 4-1. Studies Identified in the Literature
Study
Location
HUD National Lead Survey
Birmingham, Alabama
Ajo, Arizona
Alameda County (including
Oakland), California
Alameda County, California
Los Angeles County,
California
Oakland, California
Sacramento County,
California
Aspen, Colorado
Denver, Colorado
Leadville, Colorado
Telluride, Colorado
New Haven, Connecticut
Washington, DC
Washington, DC
Honolulu, Hawaii
Kellogg, Idaho
Champaign, Illinois
Chicago, Illinois
Granite City, Illinois
Indianapolis, Indiana
New Orleans, Louisiana
Portland, Maine
Baltimore, Maryland
Baltimore, Maryland
Beltsville, Maryland
Ref.
#
6
40
60
64
56
64
61
64
42
40
39
12
13
55
40
25
17
63
30
54
40
34
11
40
32
24
Abs.
#
A-11
A-10
A-27
A-31
A-28
A-31
A-30
A-31
A-22
A-10
A-9
A-18
A-15
A-36
A-10
A-17
A-12
A-32
A-20
A-34
A-10
A-16
A-25
A-10
A- 3
A-26
Year
1990
1989
1978-1979
1987-1991
1993
1987-1991
1978-1979
1987-1991
1983
1989
1987
1986
1974-1977
Unkwn
1989
1972,
1987
1983
1976
1985
1991
1989
1991
1988
1989
1982
1971-1977
#of
Samples
762
92
53
292
138
327
12
227
65
131
651
90
487
239
27
14,
18
597
288
276
338
105
na
100
27
422
108
Range
(ppm)
1-22974
89-9711
na
56-88176
22-3187
30-1973
480-7130
26-2664
135-21700
49-1331
2.7-27800
16 1895
30-7000
10-6015
99-2678
na
na
37-41200
20-1060
na
37-3010
47-4743
na
50-10900
159-3621
1-10900
0.8-246
Source
1
1
2
1
3
1
1
1
2
1
2
1,2
1
1
1
3
2
1,3
1,3
1,2
1
1,3
1
1
3
3
Supporting
Evidence
2,3,4
2
5
1,2,3,
7
1,2,3
2
1,2,3
5
2
1,8
2,5,8
1,2,3,4,6
2,8
2
5,7
1,5,6,8
2,5,7
5,7,8
2,3,4,5
2
1,3,8
1,2,3,4
2
8
5,7
Source: (1) lead-based paint; (2) point source emitter; (3) leaded gasoline emissions.
Supporting (1) residential area pattern; (2) paint-lead loading; (3) age of residence; (4) type and condition of housing;
Evidence: (5) distance from source; (6) ambient air-lead levels; (7) traffic volume; (8) community area pattern.
9
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Table 4.1 Continued
Study Ref.
Location #
Boston, Massachusetts 3
Mt. Pleasant, Michigan 10
Duluth, Minnesota 7
Minneapolis, Minnesota 7
Rochester, Minnesota 7
St. Paul, Minnesota 7
St. Cloud, Minnesota 7
Anaconda, Montana 60
Butte, Montana 41
East Helena, Montana 20
Omaha, Nebraska 26
Albuquerque, New Mexico 62
Rochester, New York 53
Cincinnati, Ohio 59
Cincinnati, Ohio 16
Bartlesville, Oklahoma 60
Palmerton, Pennsylvania 60
Charleston, 29
South Carolina
Corpus Christi, Texas 31
Dallas, Texas 23
El Paso, Texas 1 9
Midvale, Utah 22
Seattle/Tacoma 40
Washington
Mean ± 1 Standard Deviation
Estimated Isopleth Level
Source: (1) lead-based paint; (2)
Abs.
#
A-4
A-19
A-14
A-14
A-14
A-14
A-14
A-27
A-5
A-2
A-8
A-29
A-35
A-33
A-7
A-27
A-27
A-6
A-24
A-21
A-2 3
A-13
A-10
Year
1981
1990
1986
1986
1986
1986
1986
1978-1979
1990
1983
1971-1977
1981
1991-1992
1990
1980
1978-1979
1978-1979
1973
1984
1982
1972-1973
1989
1989
point source emitter; (3)
#of
Samples
195
189
32
199
19
127
13
49
650
731
185
43
528
60
80
38
42
164
485
2795
54
288
99
Range Supporting
(ppm) Source Evidence
7-13240 1,3 2,5,6,7
100-16839 1,3 1,3,4,5,6,7,
8
12-11110 1,3 1,2,7,8
35-20136 1,3 1,2,7,8
2-1930 1,3 1,2,7,8
3-7994 1,3 1,2,7,8
5-1952 1,3 1,2,7,8
na 2 5
20-2460 1,2 1,2,3,4,5
3-7964 2 5,6
16-4792 1,2,3 1,6,8
3-5280 1,3 5,7,
30-18565 1 1
2-31 661 3 3,5,6,7
76-54519 1 2,3,4
na 2 5
na 2 5
9-7890 1,3 2,4,5,7,8
8-2969 3 5,7
200-30002 2 5,8
560-11450 2 5,6
1-6665 1,2 2,3,4,5
40-7382 1 2
leaded gasoline emissions.
Supporting (1) residential area pattern; (2) paint-lead loading; (3) age of residence; (4) type and condition of housing;
Evidence: (5) distance from source; (6) ambient air-lead levels; (7) traffic volume; (8) community area pattern.
10
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4.2 SOURCE APPORTIONMENT METHODOLOGY
The process of determining the source responsible (whether based on chemistry, physical
properties, or measures of association) for elevated levels of lead in soil is commonly termed
"source apportionment." For this purpose, certain evidence or reasoning are cited in the literature
as justification for asserting that a particular source is responsible for elevated soil-lead levels.
These reasons are defined in this study as "types of supporting evidence." There were eight types
of supporting evidence identified in the literature: (1) residential area pattern; (2) paint-lead
loading on exterior walls of residence; (3) age of residence; (4) type and condition of housing; (5)
distance from a hypothesized source of elevated soil-lead levels; (6) ambient air-lead levels; (7)
traffic volume on roadways in the vicinity of area being examined; and (8) community area
pattern.
In general, each type of supporting evidence is based upon an observed relationship with
soil-lead levels. For example, residential area patterns and community area patterns are based
upon relating soil-lead levels around a home or community to the locations where the samples
were taken. Paint-lead loading on exterior walls of the residence, ambient air-lead levels, and
traffic volume on roadways are usually cited as types of supporting evidence because of an
observed positive association with soil-lead levels (i.e., higher lead loadings, air-lead levels, and
traffic volume were associated with higher soil-lead levels). Similarly, age of the residence, type
and condition of housing, and distance from hypothesized source are typically cited as supporting
evidence because the author has observed a significant association (in these cases negative) with
soil-lead levels (e.g., older, deteriorated homes associated with higher soil-lead levels).
Within the literature, a variety of methods were used to examine the relationships and
associations between the various types of supporting evidence and elevated soil-lead levels. At
the very least, most of the identified studies cite some sort of descriptive statistic such as
geometric or arithmetic means and standard deviations of lead loadings or concentrations,
stratified by levels consistent with the type of supporting evidence used (e.g., at various distances
from a source of lead). In some instances, medians and percentiles were presented. Geometric
means and medians were used by authors reporting skewed distributions for soil. Additionally,
12
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frequency counts and correlations between sampling locations and other environmental variables
such as paint-lead loading were also reported.
Analysis of variance methods and t-tests were sometimes used to compare soil-lead levels
between sample locations or to compare soil-lead levels across levels of related variables (e.g.,
by age and condition of the residence). Odds ratios and other cross-tabulation measures were
also reported. Nonparametric methods were sometimes used in place of the parametric methods
mentioned above.
Multiple and simple linear regressions were used to determine the relationship between
soil-lead levels and related variables such as traffic volume, lead-based paint loading, and
distance from the hypothesized source. Stepwise procedures were sometimes used to select the
best set of regressor variables for predicting soil-lead levels.
Some of the studies used structural equations models (SEM) to duplicate the varied
associations among the measured environmental and body burden variables, including soil on
blood-lead levels. The main idea of SEM is to construct a set of linear dependence relationships
that describe the mechanisms by which lead travels from one media or location to another.
Studies identified in this report usually used SEM to describe mechanisms by which lead goes
from a source such as lead-based paint or from a point source emitter to soil and then on to dust
or blood-lead. Thus, one of the dependent linear equations in the set usually addresses the source
of lead in soil.
Two studies, Baltimore Urban Garden Soil Study [32] and the New Orleans Lead Study
[34]. use a nonparametric test based on multi-response permutation procedures (MRPP). MRPP
was used to examine the geographic clustering of elevated soil-lead levels throughout the
community. The basic idea of MRPP is that soil samples are separated into two groups, high and
low, and a test statistic based on the geographic distance between pairs of observations in the
high group is calculated. Usually, the two groups are constructed by using the median soil-lead
value. Samples with soil-lead measurement higher than the median are put into the higher group
while the rest go into the lower group.
Kriging is another geographic method used to examine soil-lead levels throughout the
community. Kriging is a statistical interpolation method for analyzing spatially and temporally
13
-------
varying data. It is used to estimate soil-lead levels on a dense grid of spatial and temporal
locations covering the region of interest. At each location, an estimate of the soil-lead levels and
the precision of the estimate is calculated. Generally, the degree to which soil-lead
measurements taken at two locations are different is a function of the distance and direction
between the two sampling locations. Kriging differs from other classical interpolation and
contouring algorithms in that it produces statistically optimal estimates (under certain
assumptions) and associated precision measures.
4.3 LEAD-BASED PAINT
Lead-based paint was cited as one source of elevated soil-lead levels in studies across the
United States. Locations of these studies are identified in Figure 4-2. Two mechanisms for lead-
based paint contributing to soil lead have been identified. Because paint is designed to naturally
chalk, weathering of exterior lead-based paint may cause it to crumble or peel, and the resulting
paint chips and particles then contaminate the surrounding soil. Abatement of the paint using
scraping or sandblasting techniques (without an attached vacuum collection device) may also
result in lead contribution to the soil. There is varied but extensive evidence for these
mechanisms of exposure.
The literature reports four general types of supporting evidence used to demonstrate that
lead-based paint is a source of lead in soil: 1) residential or community area pattern, 2)
relationship to paint-lead loading, 3) association to age of residence, and 4) association with type
and condition of residence. Table 4-2 presents measures of central tendency (broken down by
the type of supporting evidence) as reported in studies identifying lead-based paint as a source.
In some instances, such as the Boston Brigham and Women's Hospital Longitudinal Lead Study
[3_], only a single overall central tendency measure was reported. While this central tendency
measure may not be entirely comparable to other measures reported in the table, it is included for
completeness.
14
-------
Seattle
Mmeapdis/StPaul
Portland
DUuth MtReasant
Indianapolis / Boston
Bald more
Los Angeles
Charleston
Dilwivwlvw*
bsumngnam
Figure 4-2. Locations of Studies Identified as Citing Lead-Based
Paint as a Source of Soil Lead.
Some studies identify an area pattern to lead contamination of soil at a residence. In
general, samples collected near the foundation of residences have higher lead concentrations than
samples collected at more remote locations. The geometric mean soil-lead concentrations for
samples collected at the drip line of dwelling units examined in the HUD National Lead Survey
[6] was 72 ppm (geometric standard deviation: 5.37), compared to 47 ppm (GSD: 4.14) for
samples collected at remote locations (Table 4-1). Schmitt [7] considered soil samples collected
from a number of locations surrounding residences in five Minnesota communities. As can be
seen in Table 4-2, the geometric mean soil-lead concentration was higher for foundation samples
than for open area samples1 in all of the five Minnesota communities examined (Figure 4-3). Of
the residences examined in this survey, 213 had wood exteriors and 88 were brick. The wood
exterior residences had a geometric mean soil-lead concentration of 522 ppm (geometric SD:
1 Open samples were collected from sites without buildings, such as vacant lots or undeveloped rural
areas.
15
-------
Table 4-2. Reported Measures of Central Tendency of Soil-Lead Concentrations for Studies Identifying Paint as
Responsible Source
Study Name
HUD National Lead
Survey
[A-11]
California Lead Study:
Three High Risk
Communities [A-31]
Champaign-Urbana
Lead Study [A-32]
Midvale Community
Lead Study: Final
Report [A-1 3]
Location
3O Counties
in 48 States
Alameda,
Sacrament
o, and Los
Angeles
Counties,
CA
Champaign-
Urbana, IL
Midvale, UT
Type of
Supporting
Evidence
Residential
area
pattern
Residential
Area
Pattern
Residential
Area
Pattern
Residential
Area
pattern
Description
Geometric Mean and Entryway
Std. Dev. by soil location Re
m
ot
e
Drip Line
Geometric mean by community
and sampling location
Oakland: Fr
on
t
Ya
rd
Rear Yard
Side Yard
Los Angeles: Front Yard
Rear Yard
Side Yard
Sacramento: Front Yard
Rear Yard
Side Yard
Median by location Near
Side
Lawn
Near Rear
Lawn
Far Front Lawn
Far Lawn
Geometric Mean and Perime
ter
Std. Dev. by soil locations
Garden
Bare
Surface
Mean or
Median
(ppm)
83
47
72
716
889
942
181
215
203
225
217
290
5O
1OO
7O
4O
341.81
294.59
313.20
77.95
Std.
Dev.
(ppm)
4.35
4.14
5.37
na
na
na
na
na
na
na
na
na
na
na
na
na
2.45
2.65
2.60
5.52
No. of
Soil
Samples
26O
253
415
231
141
147
290
236
245
221
197
198
na
na
na
na
112
46
88
42
-------
Table 4-2. Continued
Study Name
Minnesota Soil Lead
Study
[A-1 4]
Rochester Side-by-Side
Dust Collection Study
[A-35]
Illinois Soil Lead Study
[A-20]
Location
Duluth
Minneapolis
Rochester
St. Cloud
St. Paul,
MN
Rochester,
NY
Chicago
Chicago
suburbs
Downstate
Type of
Supporting
Evidence
Residential
Area
Pattern
Residential
Area
Pattern
Communit
y area
pattern
Description
Geometric means and Std. Dev
Duluth- Foundation
Open Area
Minneapolis- Founda
tion
Open Area
Rochester- Founda
tion
Open Area
St. Cloud- Foundation
Open Area
St. Paul- Foundation
Open Area
Geometric Mean Founda
tion
Coarse
by location Foundation
Fine
Play Coarse
Play Fine
Surface Soil
Geometric
Means for Chicago
Chicago Suburbs
Downstate
Mean or
Median
(ppm)
455
38
665
39
65
23
85
25
472
66
981
732
299
271
157
83
44
Std.
Dev.
(ppm)
5.2
2.7
3.5
3.7
8.4
4.1
7.5
4.9
4.5
3.7
na
na
na
na
na
na
na
No. of
Soil
Samples
32
19
199
51
19
15
13
18
127
95
182
182
82
82
256
244
167
-------
Table 4-2. Continued
Study Name
New Orleans Lead
Study
[A-1 6]
Omaha Lead Study [A-8]
Washington, DC Soil
Lead Study [A- 3 6]
Butte-Silver Bow
Environmental Lead
Study
[A-5]
Location
New
Orleans, LA
Omaha, NA
Washington
,DC
Butte, MT
Type of
Supporting
Evidence
Communit
y area
pattern
Communit
y area
pattern
Communit
y Area
Pattern
Paint
Loading
Description
Median by location in community
and around the home
Inner City- Foundation
Streetside
Open Area
Mid City- Foundation
Streetside
Open Area
Suburban- Foundation
Streetside
Open Area
Geometric Means Site C
by location in community Site M
SiteS
Median by City Wards Ward 1
Ward 2
WardS
Ward 4
WardS
Ward 6
Ward 7
WardS
Geometric Means O-.99
mg/cm
by paint loading 1-2.99
mg/cm2
3-1 1.99
mg/cm2
> 1 2 mg/cm2
Mean or
Median
(ppm)
840
342
212
110
110
40
50
86
28
262
339
81
444
471
54
199
222
260
144
130
2OO
3OO
65O
11OO
Std.
Dev.
(ppm)
201
723
74
220
765
80
332
195
114
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
No. of
Soil
Samples
na
na
na
na
na
na
na
na
na
69
56
51
30
30
30
30
30
30
30
30
na
na
na
na
-------
Table 4-2. Continued
Study Name
Charleston Lead Study
[A-6]
New Haven,
Connecticut Lead Study
[A-1 5]
Location
Charleston,
SC
New Haven,
CT
Type of
Supporting
Evidence
Paint
Loading
Age of
Residence
Description
Median paint loading content
(mg/cm2) by location and soil-
lead level
Porch Railing - PbS<585 ppm
PbS>585 ppm
Exterior Siding - PbS<585 ppm
PbS>585 ppm
Window Sill - PbS<58
5 ppm
PbS>585 ppm
Door Frame - PbS<58
5 ppm
PbS>585 ppm
Porch Railing - PbS<58
5 ppm
PbS>585 ppm
Geometric means and Std. Dev
by year of construction and soil
location
1910-1919 Near
Far
1920-1929 Near
Far
1930-1939 Near
Far
1940-1949 Near
Far
1950-1959 Near
Far
1960-1969 Near
Far
1970-1977 Near
Far
Mean or
Median
(ppm)
0.0
1.2
0.0
3.7
1.7
2.5
4.0
3.1
1.0
1.4
12OO.1
798.2
1273.3
77O.1
1299
917.6
444
5O7.4
929.6
479.3
3O9.7
39O.2
1 31 .3
1 1 O Q
o I \J. sy
Std.
Dev.
(ppm)
na
na
na
na
na
na
na
na
na
na
63.1
39.8
79.4
39.8
251 .2
39.8
1258.
9
316.2
398.1
100
501.2
50.1
50.1
63.1
No. of
Soil
Samples
na
na
na
na
na
na
na
na
na
na
41
41
42
42
29
29
86
86
29
29
3O
3O
3
-------
Table 4-2. Continued
Study Name
Maine Urban Soil Study
[A-25]
Cincinnati Longitudinal
Lead Study [A-7]
Mt. Pleasant Soil Lead
Study [A-1 9]
Location
Portland,
ME
Cincinnati,
OH
Mt.
Pleasant,
Ml
Type of
Supporting
Evidence
Age of
Residence
Age/condi
Housing
Condition
of Housing
Description
Geometric Mean Homes over
3O yrs old
Parks and
Playgrounds
Geometric Mean 2Oth
Century/Public
by age/condition 1 9th C.
/Rehabilitated
19th
C. /Satisfactory
19th
C. /Deteriorated
Arithmetic Excellent
Means and Excellent
Std. Dev. by G°°d
condition of „ lr
home Poor
Mean or
Median
(ppm)
1275
205
572
804
2540
2670
2O3
347
2537
1346
Std.
Dev.
(ppm)
na
na
na
na
na
na
6O
446
4631
858
No. of
Soil
Samples
75
25
14
18
7
13
6
18
13
18
-------
Table 4-2. Continued
Study Name
Albuquerque Street
Dirt Lead Study [A-29]
The HUD Abatement
Demonstration Study
[A-1 0]
Brigham and Women's
Hospital Longitudinal
Lead Study [A-4]
Granite City Lead
Exposure Study [A-34]
Identification of Lead
Sources through
Stable Isotope Ratio
Techniques: Case
Studies
[A-30]
Location
Albuquerqu
e, NM
Baltimore,
MD;
Washington
,DC
Seattle,
WA;
Tacoma,
WA;
Indianapolis,
IN;
Denver, CO;
Birmingham
,AL
Boston, MA
Granite
City, IL
Oakland, CA
Type of
Supporting
Evidence
Distance
from
Source
na
na
na
na
Description
Arithmetic Mean and Std. Dev.
by sampling locations
Site A Close
Distant
Site B Close
Distant
Site C Close
Distant
Arithmetic Means
Before
Abatement
After
Abatement
Median soil-lead level
Arithmetic Mean and Std. Dev.
Median soil-lead concentration
by case and sampling location
Case I: Backyard
Curbside
Case II: Front Yard
Side Yard
Back Yard
Neighbors
Mean or
Median
(ppm)
1170
1120
3720
2600
4860
3660
755. 0
867.5
365
449
1160
1300
2430
1420
1100
990
Std.
Dev.
(ppm)
240
190
820
180
430
220
na
na
na
42O
na
na
na
na
na
na
No. of
Soil
Samples
na
ns
ns
ns
ns
ns
455
455
195
338
2
2
4
1
2
1
-------
Table 4-2. Continued
Study Name
Telluride Lead Study [A-
18]
Location
Telluride,
CO
Type of
Supporting
Evidence
na
Description
Geometric Mean and Std. Dev
Surface Soil
Core
Mean or
Median
(ppm)
178
145
Std.
Dev.
(ppm)
2.5
3.2
No. of
Soil
Samples
45
45
na = Not available
-------
Figure 4-3.
FDN OPEN
Duluth
FDN OPEN
Minneopolis
FDN OPEN
Rochester
rxwn OPEN
FDN OPEN
St. Cloud
FDN OPEN
St. Paul
Geometric Means for Foundation and Open Samples
Reported in the Minnesota Soil Lead Study.
6.4), compared to 158 ppm (GSD: 4.3) for the brick residences. Furthermore, "virtually every
sample exceeding 2000 [ppm] and 140 of 160 samples exceeding 1000 [ppm] were collected
near house foundations." Deteriorating lead-based paint may primarily supply soils immediately
adjacent to the weathered surface.
Other studies cited a relationship between XRF lead loadings1 on exterior surfaces and
soil-lead concentrations. The Butte-Silver Bow study [41] noted that as exterior paint-lead
loading increased, the associated geometric mean of soil-lead concentration also increased (Table
4-2). Correlations are often given between soil-lead and paint-related variables as evidence of a
relationship between paint-lead loadings and soil-lead levels. Table 4-3 presents the correlations
reported in studies identified in the literature.
1 X-ray fluorescence (XRF) is a portable instrument that measures the lead-paint loading (mg/cm2). EPA
is currently examining the performance of these devices.
23
-------
Table 4-3. Correlation Results Reported Between Soil-Lead and
Exterior
Paint-Lead Variables
Study Name
The Butte- Silver Bow Environmental Health Lead Study
* Perimeter soil sample with XRF on exterior paint
Brigham and Women's Hospital Longitudinal Lead Study
* Soil Lead with paint score (based on lead-loading)
The Cincinnati Longitudinal Lead Study
* Soil Lead with XRF based paint hazard score
The HUD National Lead Survey
* Drip line soil lead with exterior paint loading
* Remote soil lead with exterior paint loading
* Entryway soil lead with exterior paint loading
Midvale Community Lead Study: Final Report
* Maximum soil-lead value with exterior XRF
New Haven, Connecticut Lead Study
* Far soil lead with exterior paint loading
* Near soil lead with exterior paint loading
Telluride Lead Study
* Surface scrape soil-lead with exterior XRF
* Soil core soil lead with exterior XRF
Rochester Side-by- Side Dust Collection Study
* Foundation Coarse soil with exterior paint XRF
* Foundation Fine soil with exterior paint XRF
Reported
Correlation
0.59
-0.07
0.41
0.41
0.40
0.38
0.43
0.28
0.43
0.40
0.49
0.37
0.34
Additionally, 102 housing units in the HUD National Lead Survey [6] with paint-lead
loadings on at least one surface measured at or above 1.0 mg/cm2 had a geometric mean soil-lead
concentration of 140.24 ppm, compared to 27.46 ppm for 80 units without any such surfaces.
These studies suggest that higher paint-lead loadings on exterior surfaces are associated with
increased lead concentration in the surrounding soil.
Age of residence is sometimes used as an indicator for the presence of lead-based paint.
The use of lead in interior and exterior house paint has markedly declined since the 1940s. In the
1970s, it was virtually banned from use in residential paints. Homes built before this period,
therefore, are more likely to contain lead-based paint. A re-analysis of the soil samples collected
in the HUD National Lead Survey [6] found dwelling unit age to be among "the strongest
predictors of soil lead." Francek [10] found the following relationship in Mt. Pleasant, Michigan
24
-------
between age of home and median soil-lead concentration at the home's foundation: less than 20
years, 200 ppm; 20-100 years, 960 ppm; greater than 100 years, 1040 ppm. He also noted a
significant correlation, 0.59, between home age and soil-lead concentration. In Portland, Maine,
Krueger [11] reported that the average soil-lead concentration collected from the foundations of
painted frame buildings at least 30 years old was higher than those collected from other
structures (Table 4-2). Figure 4-4 presents geometric means of soil-lead concentrations for
samples collected near and far from home by age of housing for the New Haven, Connecticut
Lead Study [12].
1910-1919 1920-1929 1930-1939 1940-1949 1950-1959
^^^^ Far rxyx] Near
1960-1969 1970-1977
Figure 4-4.
Geometric Means of Soil-Lead Concentrations by
Year of Construction, Near and Far Samples, New
Haven, Connecticut Lead Study.
The type and condition of the residence has also been used in place of direct measurement
of paint-lead loading. As a residence deteriorates, paint can enter the soil in the form of flakes or
chips. If the home contains lead-based paint, these paint chips could then be a source of lead in
the surrounding soil. Thus, older homes, which are more likely to contain lead-based paint, pose
25
-------
an additional hazard as these homes are also the most likely to be in poor condition. In the
Cincinnati Longitudinal Lead Study, Bornschein [16] examined the relationship between age,
26
-------
housing condition and soil-lead levels (Table 4-2). As can be seen in Figure 4-5, Bornschein
found that older, 19th-century homes in deteriorated condition have a higher geometric mean
soil-lead concentration. In addition, a lead-based paint measure, XRF-hazard, which
incorporated XRF readings with the condition of the surface sampled, was also developed. A
significant correlation coefficient between log(soil-lead concentration) and log(XRF-hazard) was
noted (Table 4-3). A study in Mt. Pleasant, Michigan [10] also documented the effect on soil-
lead concentrations from lead-based paint as the condition of the building deteriorates. In this
study, Francek found a similar relationship between median foundation soil-lead concentrations
and condition of the home (Table 4-2).
20th Century
Public
1 9th Century
Rehabilitated
19th Century
Satisfactory
19th Century
Deteriorated
Figure 4-5.
Geometric Means of Soil-Lead Concentration by Age
and Condition of Home, The Cincinnati Longitudinal
Lead Study.
4.4 POINT SOURCE EMITTERS
A point source emitter is a fixed site from which lead emanates. Examples include
operating metal smelters and refuse incinerators, areas containing mine tailings, and dump sites
for lead-acid batteries. Locations where a point source emitter has been identified as a source of
27
-------
Bute
Ajo
Figure 4-6.
Locations of Studies Identified as Citing a Point
Source Emitter as a Source of Soil Lead.
elevated soil lead are identified in Figure 4-6. Unlike leaded gasoline emissions, point-source
emissions are particular to an area. There is only a fixed range over which contamination from
the emitter may spread. Not surprisingly, the mechanisms by which surrounding soil may be
supplied with lead are varied. Mine dross, for example, may spread via erosion and airborne
transmittal. A significant portion of the literature on lead contamination has focused on point
source emitters, especially formerly operating smelters. Two general types of supporting
evidence are commonly employed in assessing point source emitters as the source of elevated
soil-lead levels: 1) distance from the source, and 2) association to ambient air-lead concentration.
Table 4-4 presents measures of central tendency of soil-lead concentrations (broken down by the
type of supporting evidence) as reported in studies identifying a point source emitter as a source
of soil lead.
Lead pollution caused by emitters is usually assessed by collecting environmental and
body burden measures from homes or individuals residing at varying distances from the point
28
-------
Table 4-4. Reported Measures of Central Tendency of Soil-Lead Concentrations for Studies Identifying Point
Source Emitters as Responsible Source
Study Name
Heavy Metal Exposure Smelter
Study [A-27]
Butte Silver-Bow Environmental
Lead Study [A-5]
Dallas Soil-Lead Contamination
Study [A-21]
El Paso, Texas Lead Study
[A-23]
Location
Bartlesville, OK;
Palmerton, PA;
Ajo, AZ;
Anaconda, MT
Butte, MT
Dallas, TX
El Paso, TX
Type of
Supporting
Evidence
Distance
from source
Distance
from source
Distance
from source
Distance
from source
Description
Median by distance from the source and
community
Bartlesville: 3.5-24.0 km
1.3-3.7 km
0.8-4.3 km
Palmerton: 1 1 .0-26.0 km
5.4-14.5 km
3.3-9.9 km
Ajo: 3.4-68.0 km
1.0-6.4 km
0.5-2.3 km
Anaconda 10. 0-26.0 km
3.5-21.0 km
2. 0-1 1.0 km
Geometric Mean and Area A
Std. Dev for Area B
perimeter soil level by Area C
community area Area D
Area E
Area F
Area G
Isopleth Estimate DMC-Smelter 1
of Lead Cone Inside Area
Outside Area
RSR-Smelter 2
Inside Area
Outside Area
Reference
Inside Area
Outside Area
Geometric Mean Area 1 (0-2.1 miles)
by proximity to Area 2 (2.1-4.2 miles)
smelter Area 3 (4.2-6.3 miles)
Within 200 meters
Mean or
Median
(ppm)
38.4
243
829
532
117
326
57.8
64.5
76.5
75
115
294
750.24
249.75
139.45
234.31
151.02
178.17
1030.56
3000
300
2500
300
500
200
1791
684
370
3457
Std.
Dev.
(ppm)
na
na
na
na
na
na
na
na
na
na
na
na
2.45
1.70
2.70
2.33
2.14
1.89
1.46
na
na
na
na
na
na
na
na
na
na
No. of
Soil
Samples
38
38
38
42
42
42
53
53
53
49
49
49
145
10
7
9
21
12
11
na
na
na
na
na
na
82
184
200
54
K>
Ul
-------
Table 4-4. Continued
Study Name
Helena Valley Lead Study [A-2]
Silver Valley - Revisited Lead
Study [A- 12]
Location
East Helena, MT
Kellogg, ID
Type of
Supporting
Evidence
Distance
from source
Distance
from source
Description
Geometric Mean by Area 1 (<1 mile)
area and soil location Comp.
Side
Play
Garden
Area 2 (1-2.25 miles)
Comp.
Side
Play
Garden
Area 3 (>5 miles)
Comp.
Side
Play
Garden
Geometric Mean Area 1 (1 mile)
by area and Comp.
soil location Foundation
Play
Garden
Area 2 (1-2.25 miles)
Comp.
Foundation
Play
Garden
Area 3 (2.56 miles)
Comp.
Foundation
Play
Garden
Mean or
Median
(ppm)
720
796
365
539
217
169
121
179
86
92
73
95
3474
5163
3616
507
2632
2512
996
978
481
541
431
318
Std.
Dev.
(ppm)
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
No. of
Soil
Samples
71
71
55
27
167
93
117
49
28
28
20
5
28
29
11
2
129
121
59
17
78
74
29
20
K)
-------
Table 4-4. Continued
Study Name
Leadville Metals Exposure Study
[A-9]
Midvale Community Lead
Study: Final Report [A-13]
Omaha Lead Study [A-8]
Aspen Garden Soil-Lead Study
IA-22J
Granite City Lead Exposure
Study [A-34]
Telluride Lead Study [A-18]
Location
Leadville, CO
Midvale, UT
Omaha, NA
Aspen, CO
Granite City, IL
Telluride, CO
Type of
Evidence
Residential
Area
pattern
Residential
Area
Community
area pattern
na
na
na
Description
Geometric Mean and Core front
Std. Dev. by residential Core rear
soil location Core play
Surface play
Surface entry
Geometric Mean and Perimeter
Std. Dev. by soil locations Garden
Bare
Surface
Geometric Means Site C
by location in community Site M
Site S
Arithmetic Mean and Std. Dev.
Arithmetic Mean and Std. Dev.
Geometric Mean and Std. Dev
Surface Soil
Core
Mean or
Median
(ppm)
1108.3
914.7
572.3
868.1
1878.9
341.81
294.59
313.20
77.95
262
339
81
172
449
145
Std.
Dev.
(ppm)
2.8
3.1
3.3
3.7
2.2
2.45
2.65
2.60
5.52
na
na
na
155
420
3.2
No. of
Soil
Samples
168
166
37
111
169
112
46
88
42
69
56
51
65
338
45
na = Not available
-------
Table 4-4. Continued
StVffy Maine
Leaityille Hetals Jxyowre-
Stwfy IA--1J
Mictyale. Community Le.ac(
Stwfy: final F-e-yort IA-1P1
Omaha Le-a^Stufa IA-X1
Alyen (jarfien $nl~Le.M( $tiA&u
lfr~££]
CfTMwte- C4ty LeM^Exvi'Mre
$tuV
Alven, M
(granite- £4ty, IL
Tellvirije, M
TyjKcf
TL\>i&e.n-(,e.
f.esic(entifd
ArtK,
vfrtttrn
f.esic(e.ntifd
ArtK,
yfrtttrn
C>VfnfnVtni.t
M MW,
vatte-m
na
na
n&
Petcriytivn
(jepsne-tric, Hean KMC( £>ore. front
5t<{. Pel/. I'M rui^entifd £>ore. re-lMr
wit location £>ore.ylcw
3vtrfac,e.ylcw
Surface, entry
(je.ome.tric Hean an<( Perimeter
•S>t((. Pei/. Vy soil locations S^ar^e-n
f>are
Svtrface-
beosnetric Me-ans Site- 0-
I'M location in cosnsnMnity Site- At
SiteS
Arithmetic Me-an anc( Stc(. Pei/.
Arithmetic Me-an anc( Stc(. Pei/.
geometric Hean an<( St<{. Pei/
Surface. Soil
&vre.
Me<
Me,
ft
m
11
n
n
W
?4
£
r
4
1
1-
na = Not available
-------
source. Often, the community is partitioned into three or more areas of varying distance from the
point source emitter (Table 4-4). For example, in the Silver Valley-Revisited Lead Study [17]
the community was partitioned into three concentric rings emanating from the smelter site. The
soil-lead levels from various locations, such as foundation or play areas, were then compared
over the locations to determine if differences exist due to distance from the point source. Figure
4-7 displays geometric means of lead loading for composite soil samples by distance from point
source for three smelter studies: El Paso, Texas Lead Study [19]. Helena Valley Lead Study [20].
and Silver Valley-Revisited Lead Study [17]. In the Midvale Community Lead Study [22] a
correlation coefficient of-0.68 between maximum soil-lead concentration at the residence and
the distance to the mill building was reported. Brown [23] used geostatistical methods to
generate isopleths of constant soil-lead concentrations in the area of two Dallas, Texas smelters.
The isopleths, which show increasing soil-lead concentrations in the vicinity of the smelters,
"support the conclusion that the smelters are the primary sources of lead contamination in the
area." In addition, the Heavy Metal Exposure Study [60] found that "there was a general trend
toward increasing levels of environmental metal burdens with proximity to the smelter." The
evidence for the emitter being the contributing source of the lead, therefore, stems from
increasing soil-lead concentrations with decreasing distance from the emitter.
£.1 — 4.2 4.2 —S.3
Raso I
:1 1 —2.25
h Silver Valley
Figure 4-7.
Geometric Means of Lead Loading for Composite Soil
Samples by Distance from Point Source (miles).
33
-------
In those instances where the emitter consistently produces airborne lead emissions,
relationships may sometimes be drawn between ambient air-lead levels and soil-lead
concentration. The Silver Valley-Revisited Lead Study [17] conducted in northern Idaho, for
example, found a 0.52 correlation coefficient between composite soil-lead concentration from the
residence and ambient air-lead levels. Other studies have noted that soil-lead concentrations may
follow geographical distributions similar to those determined for ambient air-lead levels [19]. If
the emitter is the primary active source of lead into the environment, it should not be surprising
to find associations between ambient air-lead levels and soil-lead concentration.
4.5 LEADED GASOLINE EMISSIONS
Until its phase-out in the 1980s, the primary use of lead in the United States was as a
performance additive to gasoline. Unfortunately, most of that lead (approximately 75%) was
discharged into the environment through vehicle exhaust. The emitted lead particles have spread
well beyond the confines of the roadway. After decades of leaded gasoline usage, the
environment now contains a tremendous reservoir of lead. This reservoir is retained in the
surrounding soil and dust. Locations where leaded gasoline emission has been identified as a
source of elevated soil lead are identified in Figure 4-8.
Studies of this source of contamination have included assessments of soil-lead
contamination near highways and the implications of leaded gasoline emissions in the urban
environment. Four general types of supporting evidence have been used within the literature in
examining leaded gasoline as a source of lead in soil: 1) distance from the roadway, 2)
association with ambient air-lead levels, 3) association with traffic volume, and 4) community
area pattern. Table 4-5 presents measures of central tendency of soil-lead concentrations (broken
down by type of supporting evidence) as reported in studies identifying gasoline emissions as a
source of soil lead.
34
-------
Mm&pdis/StRaul
M Pleasant
Figure 4-8.
Locations of Studies Identified as Citing Gasoline
Emissions as a Source of Soil Lead.
Approximately, 40% of the lead emitted as vehicular exhaust is in sufficiently large
particles to be deposited near the roadway. It seems reasonable, therefore, that soil-lead
concentration would decrease with increasing distance from the roadway. This, in fact, is borne
out in the literature. A longitudinal study of soil-lead concentration adjacent to a newly
constructed roadway conducted near Beltsville, Maryland [24] noted that, "soil Pb levels
decreased with distance from the roadway [8, 25, 50 meters] and with depth [0-5, 5-10, 10-15
cm] in the soil profile." (Figure 4-9, Table 4-5). In Honolulu, Hawaii, Fu [25] noted that soil-
lead concentration from a boulevard median strip adjacent to a park was 1650 ppm, and that,
"elsewhere through the park, soil [lead levels] fell with distance from the boulevard but rose
again as the beach road was reached." Even in the more rural community of Mt. Pleasant,
-------
Francek [10] measured median soil-lead concentration in roadside soils of 280 ppm (range: 100-
840 ppm), compared to 200 ppm (range: 100-220 ppm) in background soils.
36
-------
Table 4-5. Reported Measures of Central Tendency of Soil-Lead Concentrations for Studies Identifying Gasoline
Emissions as Responsible Source
Study Name
Albuquerque Street
Dirt Lead Study
Beltsville Roadway
Study
Corpus Christi Soil
Lead Study
Location
Albuquerqu
e, NM
Beltsville,
MD
Corpus
Christi, TX
Type of
Supporting
Evidence
Distance
from
Source
Distance
from
source
Distance
from
source
Description
Arithmetic Mean and Std. Dev. by
sampling locations
Site A Close
Distant
Site B Close
Distant
Site C Close
Distant
Arithmetic Mean and East Side
Std. Dev. by side and 8
me
ter
s
distance from roadway, 25
me
ter
s
samples collected O-5 cm 5O
me
ter
s
in depth West Side
8 meters
25 meters
5O meters
Arithmetic mean
and Std. Dev Near Major Highways
Not Near Major
Highways
Parks
Schools
Mean or
Median
(ppm)
177O
11 2O
372O
26OO
486O
366O
108.8
32.72
14.16
87.37
25.42
19.2
250
55
57
Std.
Dev.
(ppm)
24O
19O
82O
18O
43O
22O
98.6
18.29
8.49
60.46
8.96
4.88
250
66
77
No. of
Soil
Sampl
es
na
ns
ns
ns
ns
ns
5
5
5
7
7
7
379
94
12
-------
Table 4-5. Continued
Study Name
Charleston Lead Study
Location
Charleston,
SC
Type of
Supporting
Evidence
Traffic
Volume
Description
Median traffic volume Facing Street
(cars/day) by location Pb
S<5
85
and soil level (ppm) PbS>585
All Streets w/in 76m
PbS<585
PbS>585
Mean or
Median
(ppm)
100
100
8875
8550
Std.
Dev.
(ppm)
na
na
na
na
No. of
Soil
Sampl
es
na
na
na
na
38
-------
Table 4-5. Continued
Study Name
Cincinnati Roadside
Soil Study
Illinois Soil Lead Study
Mt. Pleasant Soil Lead
Study
Baltimore, MD Urban
Garden Soil Study
Champaign-Urbana
Lead Study
Location
Cincinnati,
OH
Chicago, IL
Mt.
Pleasant,
Ml
Baltimore,
MD
Champaign-
Urbana, IL
Type of
Supporting
Evidence
Traffic
Volume
Traffic
Volume
Traffic
Volume
Area
Pattern
Residential
Area
Pattern
Description
Arithmetic Mean and Std. Dev by
Average Daily Traffic Volume
>20,000
8,000-20,000
<8,000
Arithmetic mean and <5O
00
Std. Dev. for surface 5O
00-
99
99
samples not near play 1 0
00
0-
19
99
9
equipment by traffic 2O
00
0-
49
99
9
volume (cars/day) >5O
00
0
Arithmetic means and Std. Dev. by
average daily traffic volume
Heavy (ADT: >2OOOO)
Moderate (ADT:8OOO-
20000)
Light (ADTxSOOO)
Median for all inner city residences
(largely non-painted brick)
Median by location Near Side Lawn
Near Rear Lawn
Far Front Lawn
Far Lawn
Mean or
Median
(ppm)
1125.7
999.7
886.9
90
141
187
265
236
343
345
286
1OO
50
100
70
40
Std.
Dev.
(ppm)
1282.
8
1043.
5
623.5
13
33
23
26
41
1O6
17O
126
na
na
na
na
na
No. of
Soil
Sampl
es
60
60
60
96
30
77
87
63
33
14
26
422
na
na
na
na
-------
Table 4-5. Continued
Study Name
Minnesota Soil Lead
Study
New Orleans Lead
Study
Omaha Lead Study
Survey of Lead Levels
Along Interstate 88O
Brigham and Women's
Hospital Longitudinal
Lead Study
Location
Duluth
Minneapolis
Rochester
St. Cloud
St. Paul,
MN
New
Orleans, LA
Omaha, NA
Alameda
County, CA
Boston, MA
Type of
Supporting
Evidence
Residential
Area
Patterns
Communit
y area
pattern
Communit
y area
pattern
na
na
Description
Geometric means and Std. Dev
Duluth- Foundation
Open Area
Minneapolis- Foundation
Open Area
Rochester- Foundation
Open Area
St. Cloud- Foundation
Open Area
St. Paul- Foundation
Open Area
Median by location in community and
around the home
Inner City- Foundation
Streetside
Open Area
Mid City- Foundation
Streetside
Open Area
Suburban- Foundation
Streetside
Open Area
Geometric Means Sit
eC
by location in community Site M
SiteS
Arithmetic Mean East of Highway
West of Highway
Median soil-lead level
Mean or
Median
(ppm)
455
38
665
39
65
23
85
25
472
66
840
342
212
110
110
40
50
86
28
262
339
81
594.3
263.3
365
Std.
Dev.
(ppm)
5.2
2.7
3.5
3.7
8.4
4.1
7.5
4.9
4.5
3.7
201
723
74
220
765
80
332
195
114
na
na
na
na
na
na
No. of
Soil
Sampl
es
32
19
199
51
19
15
13
18
127
95
na
na
na
na
na
na
na
na
na
69
56
51
116
22
195
-------
Table 4-5. Continued
Study Name
Honolulu Park Soil Lead
and Mercury Study
Location
Honolulu, HI
Type of
Supporting
Evidence
na
Description
Arithmetic Means and 1 9
72
Sur
vey
Std. Dev. 1 987 Survey
Mean or
Median
(ppm)
467
367
Std.
Dev.
(ppm)
93
37
No. of
Soil
Sampl
es
14
18
na = Not available
41
-------
I
100
90
80
70
60
50
40
30
20
10
10
20 30
Dtatnnos Itorn RoochMy QjnBtora^
t of highway e-o o wnt of Highway
40
60
Figure 4-9. Arithmetic Mean Soil-Lead Concentrations for O-5 cm
Samples Collected 8, 25, and 5O Meters from a Roadway,
Beltsville Roadway Study.
Some studies have found associations between ambient air-lead levels and the
concentration of lead in the surrounding soil. Even if a point source emitter is not located
nearby, such association may suggest leaded gasoline as a source only if the study was conducted
while leaded gasoline was still commonly utilized. A 1977 study in Omaha, Nebraska reported a
0.37 correlation coefficient between ambient air-lead levels and composite residence soil-lead
concentration [26]. Similarly, a Boston, Massachusetts study in the early 1980s estimated a 0.18
correlation coefficient [3_]. Both studies were conducted while leaded additives were prevalent.
With the phase-out of these additives, such associations are unlikely to be observed, but there are
other approaches, such as tracer analysis, for considering the extent of the relationship between
leaded gasoline emissions and lead in soil.
Soil-lead concentrations were also analyzed as a function of traffic volume on nearby
roadways. As the number of vehicles emitting lead exhaust increases, one would expect the lead
concentration in surrounding soil to elevate. In Charleston, South Carolina, Galke [29] noted
42
-------
that for residences with soil-lead concentration less than 585 ppm, the median traffic volume
within 250 feet was 1100 cars/day. In contrast, residences with soil-lead concentration exceeding
585 ppm had a median traffic volume of 3200 cars/day. Figure 4-10 shows arithmetic means of
soil-lead concentrations by traffic volume as reported in the Illinois Soil Lead Study [30].
1000
100
1O-1-
10000~ 2000O~
IMIto VWurm (ow* p«r day)
Figure 4-10. Arithmetic Means of Soil Lead Concentrations by
Traffic Volume as Reported in the Illinois Soil Lead
Study.
Some authors have hypothesized that traffic volume alone is insufficient to explain the
nearby soil-lead levels. Harrison [31]. for example, suggests that the velocity of the traffic is also
important. Heavily congested roadways with gridlocked, idling traffic may produce higher soil-
lead levels than more rapidly moving traffic. There is some evidence to support this hypothesis.
Researchers have found that soil-lead concentration area patterns in communities often
follow the highway infrastructure. This is particularly true in urban environments. Mielke has
reported that the highest lead concentrations in soil in both Baltimore [32] and Minneapolis-Saint
Paul [33] were clustered toward the center of the city. Preliminary results in the city of New
Orleans [34] suggested a similar pattern. In the case of Baltimore, the probability that the
clustering occurred by chance was less than 10"23. Furthermore, "the most consistently high
43
-------
garden soil Pb levels were found in the area of the city that was predominantly unpainted brick
buildings [3_5]." In Corpus Christi, Texas [31]. soil-lead concentration was reported to be
concentrated in and around its roadways. Angle examined three communities in Omaha,
Nebraska [26]: a suburban neighborhood (S), an urban-commercial area (C), and an urban area
contiguous to downtown (M) (Table 4-5). Most inner cities have tightly clustered, congested
roadways. These roadways spread out as they emanate from the city's center. Leaded gasoline
emissions appear to have often polluted the surrounding soil accordingly.
5.O CONCLUSIONS
This study confirmed the commonly assumed pairwise associations between elevated
soil-lead levels and lead-based paint, leaded gasoline emissions, or point source emissions. Such
a confirmation is not altogether surprising, but it is an important step in any effort to reduce and
preclude childhood exposure to elevated soil-lead concentrations. No definitive evidence was
found within the literature, however, suggesting a particular source can be regularly identified as
responsible for elevated soil-lead concentrations at a residence. In fact, many studies cite more
than one source as commonly responsible for elevated soil-lead levels. Moreover, labor- and
cost-intensive techniques for carefully apportioning the sources of in soil suggest varying relative
contributions from candidate sources. It may be possible on a case-by-case basis to apportion the
responsible sources, but no generalizations are possible based on readily obtained categorical
factors (e.g., urban verus rural, northeast versus southwest). Nevertheless, as the associations
between these sources and elevated soil-lead levels have been confirmed, interventions targeting
these sources should prove beneficial in reducing the instances of elevated lead levels in soil. In
particular, lead-based paint interventions, such as those prompted by promulgation of the §403
standards, will have the additional benefit (above and beyond any benefit seen in reduced indirect
exposure to elevated dust-lead levels and direct exposure to paint chips) of removing a source of
lead in soil.
In many communities, the elevated soil-lead levels are due to a combination of sources,
and it is often difficult to determine whether the elevated soil-lead levels are a function of a point
source emitter, lead-based paint, or leaded gasoline emissions. Lead contamination of soil is
additive; additional sources simply increase the extent of the contamination. One difficulty in
determining which potential source contributes to elevated soil-lead levels, therefore, is due to
44
-------
the fact that there are often multiple sources within a community. In addition, differences in
study design and confounding regional differences also hinder attempts to determine whether a
particular source is responsible for elevated soil-lead levels.
Rural environments with old, painted structures or urban communities with brick
buildings may be easily classified. Urban communities with painted structures, however, are
more difficult. Even more complex to classify are those cities with smelter or waste incinerator
sites. Urban renewal, soil erosion, and landscaping confound the issue. The problem stems, to
some extent, from the mechanism of lead contamination by vehicular emissions. Whereas
approximately 40% of the discharged lead from leaded gasoline was in large particles, 35% or so
was in the form of tiny particles able to disperse over large areas from the roadway [1]. In a
typical urban environment, these small particles may have spread lead over the majority of the
city. The extent of resulting lead exposure may be a function of wind direction and weather
pattern. Chaney and Mielke [35]. among others, assert that the particles, "waft through the city
and adhere to surfaces they come in contact with." These particulates may then be washed down
into the surrounding soil. Areas with large surfaces would, by this hypothesis, attract more of
these small particles. This suggests that elevated soil-lead concentration at an urban residence's
foundation may not strictly be a function of lead-based paint. Elevated levels may also stem
from leaded gasoline emissions due to the large surface area presented by the external walls and
roof of the residence. For residences with large yards, this suggests a pattern of soil lead
exposure highest near the roadway, gradually decreasing toward the center of the yard, only to
elevate again near the residence's foundation.
While there is no definitive assessment concerning this hypothesis, some supporting
evidence does exist. Soil samples collected next to the roadways in the Twin Cities [46] were
found to be closely related to samples collected at the foundations of adjacent residences. A
significant correlation coefficient of 0.72 was reported. Linton [36] employed sophisticated
source identification techniques to inspect a foundation soil sample collected next to a brick
building with lead-based paint covering the window trim. Despite the building being more than
50 feet removed from a major roadway (2000 cars/day), "it is estimated that 80-90% of lead
present in this building line sample is derived from paint chips with the remaining 10-20% being
of automobile origin." In addition, a few studies such as Mt. Pleasant Soil Lead Study [10] have
45
-------
found elevated foundation soil-lead concentration near modern homes. Due to the fact that these
are modern homes, they were considered to have a low risk of containing lead-based paint.
Another complicating factor in identifying the responsible source of soil-lead
concentration is that many cities in the United States grew outward from a central core. Older
homes, which are more likely to have been coated with lead-based paint, are typically located in
the center of the city. Thus, residences with lead-based paint already elevating their surrounding
soil were also exposed to higher leaded gasoline emissions. Differentiating between the two
prospective sources becomes extremely difficult. If these same communities are also the city's
poorest, the deteriorated condition of the dwellings make differentiation nearly impossible.
Finally, regional differences are often confounded with differences in study design and
objectives. In many cases, the age distribution and composition of the sampled houses differs
from region to region across the United States. In addition, the soil composition and background
levels may vary substantially from region to region. These regional differences hinder attempts
to compare from study to study, the relative contamination from a particular source. There are
simply too few studies conducted under sufficiently similar circumstances to allow reasonable
comparison. For this reason, it is difficult to make any sweeping generalizations about the
geographic distribution of the sources of elevated soil lead.
It does appear, however, that lead-based paint is often responsible for higher
concentrations of lead in the surrounding soil. Within the literature, the highest soil-lead
concentration levels are invariably at the foundation of buildings with flaking lead-based paint.
For example, geometric mean soil-lead concentrations adjacent to wood-sided residences were
more than three times higher than those adjacent to brick residences (522 ppm/158 ppm) in the
Minnesota Soil Lead Study [7]. Whereas leaded gasoline emissions spread their lead exposure
over a wide area, lead-based paint likely contaminates a relatively small region about the
residence. The remarkably high concentrations of lead found in the soils adjacent to residences
may be a function of the sheer volume and concentration of lead in the painted surfaces.
46
-------
6.O REFERENCES
Reference Abstract Citation
Number Number
1. na U.S. Department of Health and Human Services. (1991) "Preventing
Lead Poisoning in Young Children — A Statement by the Centers for
Disease Control," Public Health Service.
2. na Shacklette, H. T. and Boerngen, J. G. (1984) "Element Concentrations
in Soils and Other Surficial Materials of the Conterminous United
States," U.S. Geological Survey Professional Paper 1270, U.S.
Government Printing Office, Washington D.C.
3. A-4 Rabinowitz, M. B. and Bellinger, D. C. (1988) "Soil Lead - Blood
Lead Relationship among Boston Children," Bulletin of
Environmental Contamination and Toxicology. 41:791-797.
4. A-4 Rabinowitz, M., Leviton, A., Needleman, H., Bellinger, D., and
Waternaux, C. (1985) "Environmental Correlates of Infant Blood
Lead Levels in Boston," Environmental Research. 38:96-107.
5. A-l 1 Weitz, S., Clickner, R. P., Blackburn, A., Buches, D., et al. (1990)
"Comprehensive and Workable Plan for the Abatement of Lead-Based
Paint in Privately Owned Housing: Report to Congress," U.S.
Department of Housing and Urban Development, Washington, D.C.
6. A-l 1 Rogers, J., Clickner, R., Vendetti, M., and Rinehart, R. (1993) "Data
Analysis of Lead in Soil," U.S. Environmental Protection Agency,
Office of Pollution Prevention and Toxics, Report Number EPA 747-
R-93-011.
7. A-14 Schmitt, M. D. C., Trippler, D. J., Wachtler, J. N., and Lund, G. V.
(1988) "Soil-Lead Concentrations in Residential Minnesota as
Measured by ICP-AES," Water, Air, and Soil Pollution. 39:157-168.
8. A-14 Mielke, H. W., Adams, J. L., Reagan, P. L., and Mielke, P. W., Jr.
(1989) "Soil-Dust Lead and Childhood Lead Exposure as a Function
of City Size and Community Traffic Flow: The Case for Lead
Abatement in Minnesota," In: Lead in Soil: Issues and Guidelines,
Supplement to Volume 9 of Environmental Geochemistry and Health.
Edited by Davis, B. E. and Wixson, B. G., pp 253-271.
9. A-14 Trippler, D. J., Schmitt, M. D. C., and Lund, G. V. (1989) "Soil Lead
in Minnesota," In: Lead in Soil: Issues and Guidelines, Supplement to
Volume 9 of Environmental Geochemistry and Health. Edited by
Davis, B.E. and Wixson, E.G., pp 273-280.
47
-------
Reference Abstract Citation
Number Number
10. A-19 Francek, M. A. (1992) "Soil-Lead Levels in a Small Town
Environment: A Case Study from Mt. Pleasant, Michigan,"
Environmental Pollution. 76:251-257'.
11. A-25 Krueger, J. A. and Duguay, K. M. (1989) "Comparative Analysis of
Lead in Maine Urban Soils," Bulletin of Environmental
Contamination and Toxicology. 42:574-581.
12. A-18 Bornschein, R. L., Clark, S., Grote, J., Peace, B., Roda, S., and
Succop, P. (1988) "Soil Lead-Blood Lead Relationship in a Former
Lead Mining Town," In: Lead in Soil: Issues and Guidelines,
Supplement to Volume 9 of Environmental Geochemistry and Health.
Edited by Davis, B.E. and Wixson, E.G., pp 149-160.
13. A-15 Stark, A. D., Quah R. F., Meigs, J. W., and DeLouise, E. R. (1982)
"The Relationship of Environmental Lead to Blood-Lead Levels in
Children," Environmental Research. 27:3 72-3 83.
14. A-7 Bornschein, R. L., Hammond, P. B., Dietrich, K. N., Succop, P.,
Krafft, K., Clark, S., Berger, O., Pearson, D., and Que Hee, S. (1985)
"The Cincinnati Prospective Study of Low-Level Lead Exposure and
Its Effects on Child Development: Protocol and Status Report,"
Environmental Research. 38:4-18.
15. A-7 Que Hee, S. S., Peace, B., Clark, S., Boyle, J. R., Bornschein, R. L.,
and Hammond, P. B. (1985) "Evolution of Efficient Methods to
Sample Lead Sources, Such as House Dust and Hand Dust, in the
Homes of Children," Environmental Research. 38:77-95.
16. A-7 Bornschein, R. L., Succop, P. A., Krafft, K. M., Clark, C. S., Peace,
B., and Hammond, P. B. (1986) "Exterior Surface Dust Lead, Interior
House Dust Lead and Childhood Lead Exposure in an Urban
Environment," Conference in Trace Metals in Environmental Health,
Columbia, MO.
17. A-12 Panhandle District Health Department, Idaho Department of Health
and Welfare, Centers for Disease Control, and U.S. Environmental
Protection Agency. (1986) "Kellogg RevisitedSl983: Childhood
Blood Lead and Environmental Status Report," Final Report of the
U.S. Public Health Service.
18. A-12 Yankel, A. J., von Lindern, I. H., and Walter, S. D. (1977) "The Silver
Valley Lead Study: The Relationship Between Childhood Blood Lead
Levels and Environmental Exposure," Journal of the Air Pollution
Control Association. 27(8): 763-767.
48
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Reference Abstract Citation
Number Number
19. A-23 Landrigan, P., Gehlbach, S., Rosenblum, B., Shoults, J., Candelaria,
R., Barthel, W., Liddle, J., Smrek, A., Staehling, N., and Sanders, J.
(1975) "Epidemic Lead Absorption Near an Ore Smelter: The Role of
Particulate Lead," New England Journal of Medicine. 292(3): 123-
129.
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