Section 1:  Introduction
 
 


Introduction

The Facts:

Lead

The elevated levels are due:

 
Though lead has been banned in residential paints since 1978 (banned in Europe since 1904), 80% of all homes that were built prior to 1978 are still coated in lead-based paints.  The unsafe removal of indoor paint as well as the deterioration of the outside paint contributes to lead accumulation in soil. In addition, precipitation runoff from weathered, lead painted houses significantly adds to the lead contamination present in the soil beneath the drip lines of these structures.
Urban Areas

Urban areas are of particular concern for elevated lead levels in children since there is a greater concentration and a longer history of emission sources, a higher traffic density, and a large quantity of older houses.  While hot spots from lead-based paint hazards and industrial activity are located in socio-economic strata, the overall “background” level of lead from all sources is higher in inner cities (Brody et al., 1994).  Studies of cities within Maryland, Minnesota, and Louisiana have shown that the greatest amount of lead in soil can be found in the central part of the city where the highway networks concentrate traffic (Mielke et al., 1989).

 

While lead poisoning affects nearly every system in the body, lead poisoning doesn’t have distinct visible symptoms.  The Agency for Toxic Substances and Disease Registry (ATSDR) cites that high lead levels in children can impair physical and mental development as well as cause premature births, stunt growth, and cause learning difficulties in children.  In adults, lead exposure can weaken the fingers, wrists, or ankles, impair memory, cause anemia, abortion, and damage the male reproductive system (ATSDR, 1993).  More importantly, low-level lead exposure can have profound, adverse physiological and cognitive effects that can have long-lasting impacts.

Association with Soil Pb Concentrations

Blood lead levels in the whole population of U.S. children have decreased dramatically since federal lead-based hazard intervention programs (e.g., U.S. Consumer Product Safety Commission, 1978; Leaded gasoline phase-out, EPA 40 CFR Part 80; The Residential Lead-Based Paint Hazard Reduction Act of 1992); however, the problem still exists in urban areas.  While the age of housing is an important risk factor for determining lead exposure, the association between soil lead concentrations and blood lead levels has been revealed to be 12 times stronger than the association between the age of the housing and blood lead levels (Mielke, 1999).  Based on research conducted in urban neighborhoods, Mielke (1999) demonstrated that, “housing tracts with low levels of lead in the soil are very strongly associated with low blood-lead concentrations, whereas areas high in soil lead are likewise associated with high blood-lead concentrations.”  In addition, there is a strong correlation between child blood lead levels and the time spent outdoors (Binns, 1999).  Children are especially at risk because much of the lead exposure from the soil is through hand-to-mouth contact.

These studies suggest that the creation of lead-free housing is not nearly sufficient, as lead-free housing must address lead in the soils.

Several government reports and publications recognize that the greatest risk to lead is through leaded dust and contaminated soil (e.g., EPA 40 CFR Part 745).  To reduce exposure to soil-based contaminants, the most appropriate measure is to prevent or limit children’s exposure to bare soil, especially contaminated soils in play areas next to urban, residential dwellings.  It is imperative that the contaminated soils are covered and maintained with dense, vigorous vegetation or an alternative barrier (i.e., mulch, rubberized surface, concrete, etc.).

Controlling lead exposure from soils is especially important in the Chicago metropolitan area since a large percentage of Chicago children have elevated blood-lead levels.  In a 1996 report, it was reported that Chicago has one of the highest incidences of lead poisoning in the United States (Lanphear, 1996).  Communities within the Chicago Housing Authority (CHA) have a history of high soil lead levels, as shown in the Table below.   If the CHA is to fully address the elevated blood-lead levels of children in its communities, a program must be created to eliminate the exposure to lead contaminated soil.  This project’s goal was to design a program to install or construct barriers and/or remove lead contaminants from the soil which can be implemented as part of the Chicago Housing Authorities’ Plan For Transformation, which plans to provide environmentally safe housing for its residents.
Primary Project Objective

The primary objective of this project was to create a decision tree for landscape designs that focuses on the stabilization and removal of lead from contaminated soils in CHA communities through the employment of phytoremediation.  This decision tree will be used as the basis for soil testing, landscape design and maintenance, soil and plant lead-level monitoring, and decision making for current and future CHA communities.
 

Project Origins

On September 30, 1999, the Chicago Housing Authority (CHA) drafted for public comment the “Chicago Housing Authority: Plan for Transformation - Improving Public Housing in Chicago and the Quality of Life” (See Appendix A).  This plan calls for radical changes and improvement to the CHA.  Plan highlights include (CHA, 2000):


Even with a large financial capital program and a goal of providing environmentally safe housing, the CHA does not specifically have plans for protecting residents from lead and other contaminants from the soil at CHA communities as pointed out by Keith Harley of the Chicago Legal Clinic.  While CHA will be providing their residents with lead-safe units within five years, they will continue to allow residents to be exposed to lead and other contaminants in the outdoor common areas of their communities.  CHA is not making a strong effort to minimize or eliminate the danger caused by exposure to these contaminants.  Mr. Harley feels that modifying current practices can eliminate this exposure.  Within the framework of actions already engaged, CHA can develop landscaping, landscape maintenance, and lead monitoring routines that incorporate the use of plants and other techniques that will greatly reduce, even eliminate, the bioavailability of lead and other contaminants.

Summary of Lead Concentrations in CHA Communities.
CHA Development
Total Number of Samples
% of samples that did not meet the EPA play area standard (> 400 ppm)
Cabrini Row
46
85 %
Brooks Homes
63
68 %
Wells Homes
98
65 %
Wentworth Gardens
31
58 %
Lawndale Gardens
20
50 %
Bridgeport Homes
15
47 %
Robert Taylor A
62
32 %
Hillard Family Center
11
36 %
Jane Addams
26
31 %
Trumbull Park
28
29 %
Altgeld Gardens
107
26 %
Cabrini Ext.
74
24 %
Green Homes
43
23 %
Ickes Homes
44
16 %
Abbott High
20
15 %
1440 W. 13th St.
20
15 %
Brooks Ext.
18
11 %
Robert Taylor B
87
10 %
Stateway Gardens
96
8 %
Dearborn Homes
41
7 %
Wells Ext.
126
4 %
Madden Park
133
3 %
Lathrop Homes
44
2 %
Darrow Homes
4
0 %
Lowden Homes
15
0 %
Ickes-Prarie Cts Ext.
14
0 %
Lawndale Complex High
2
0 %
Lawndale Complex Low
6
0 %
Abbott Row
21
0 %

The CHA’s own Lead Hazard Priority List (Table) indicates that lead levels that are in excess of federal standards characterize many current CHA communities.  Overall, of the 1,581 samples taken throughout CHA, almost 25% are in excess of the EPA established standard for response activities for residential lead-contaminated soil of 400 parts per million (ppm).  Of the 29 CHA housing communities tested in which data are available, only six lack lead contamination:  Darrow, Ickes-Prairie Courts Ext. Lowden, Lawndale Complex High, Lawndale Complex Low, and Abbott Row.  In contrast, in five communities, 50% or more of the samples were in excess of the EPA standard for children play areas of 400 ppm.  These communities are Cabrini Row, Brooks Homes, Wells Homes, Wentworth Gardens, and Lawndale Gardens.  In six other communities, more than 25% of the samples exceeded 400 ppm.  In total, there are eighteen CHA housing communities where 10% or more of the soil samples exceed federal standards for lead in soil where children play.

Professors and students of Northwestern University have developed a proposal through which phytoremediation, or the use of grasses and plants, is employed to address soil contamination in residential communities.  There are three main ways in which certain grasses and plants can help reduce exposure to soil contamination.  First, they can create a barrier, thus eliminating the exposure route between the contaminated soil and the children that play on the soil.  Second, certain grasses and plants can absorb contaminants into their root system, thus reducing contaminant bioavailability to other organisms and decreasing general exposure in the bulk soil through a process called phytosequestration.  Finally, some plants can actually be used to remediate the soil, either through naturally occurring processes within the plants or by harvesting and removing plants that are capable of accumulating the contaminants.

Phytoremediation is a relatively new technology that has been gaining commercial acceptance as research on the field scale has confirmed greenhouse and pilot scale success.  While it has been used mainly in open, industrial settings (e.g., USAEC, 2000; EPA, 2000a; Phytotech, 1999), phytoremediation has been used in several urban, residential applications for lead reduction.  For example, in Massachusetts phytoremediation significantly reduced high soil lead levels in both an open lot that was revitalized into a community garden (EPA, 1999) and in an urban residential backyard (Blaylock, 2000).  In the case of the community garden, several plantings of Indian mustard lowered the lead levels that initially exceeded 1000 ppm to concentrations less than half that amount.  While phytoremediation in a full-scale residential application presents a few more challenges than that in an industrial site or an isolated lot, it can be successfully implemented over time through the use of a comprehensive monitoring and planting regime.
 

Project Summary

A number of CHA communities have been found to have significant amounts of lead and other contaminants present in the buildings and soil.  The CHA’s Plan For Transformation calls for environmentally friendly housing units to be developed over the next 10 years; however, there are no plans to address the contaminants in the soil.  In some cases, new communities are being developed.  Even in these new locations, there is a strong possibility that there will be lead contamination in the soil due to the generally elevated lead-soil levels throughout Chicago.  Acquiring independent contractors to run the CHA communities (as stated in the Plan For Transformation) gives CHA the opportunity to specify through contractual agreements strategies that address contamination problems in the soil.  This project is not solely applicable to the CHA and the Chicago area, but rather addresses a national urban problem.  Thus, this project could be of benefit to other communities looking to reduce the exposure to lead in soil.

This project involves the use of phytoremediation, as well as soil and plant enhancement techniques, as the method to prevent residents from being exposed to soil-associated contaminants.  The final result is a comprehensive decision tree for the CHA.  This decision tree serves as a guide on how to employ this technology to protect human and ecological health, enhance the quality of life, improve aesthetics, and build community involvement; all in a cost effective manner for an urban residential area.