This study evaluated the risk factors for elevated blood lead levels in children in Milwaukee from 1996-2011. The results showed: - Children living in pre-1940 homes had a significantly higher risk of elevated blood lead levels compared to post-1940 homes, and the risk was highest for children aged 0-24 months. - Renter-occupied homes had twice the risk of owner-occupied homes. - Lead abatement of pre-1940 homes reduced the risk of elevated blood lead levels by 31%, and primary prevention efforts reduced the risk by 44%. - The annual reduction in lead poisoning prevalence and incidence was strongly correlated with the number of pre-1940 homes abated in Milwaukee.

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Pre-1940 Home Lead Abatement and Elevated Blood Lead Levels in Milwaukee, WI
• Introduction: In the United States, childhood lead poisoning rates were reduced from 7.61% to 0.56%,
between 1997 and 2011, because of public health primary prevention efforts. From 1997 to 2011, the
City of Milwaukee Lead Poisoning Prevention Program reduced these rates from 31.9% to 3.2%.
Identifying variables that contribute to effective lead abatement efforts may provide a successful
roadmap for future intervention efforts among comparable communities.
• Objectives: We evaluated the influence of housing characteristics on the risk for elevated blood lead
levels (≥10 μg/dL) among children in Milwaukee, WI from 1996 – 2011. Further, we investigated the
effect of lead abatement on reducing the prevalence and incidence of lead poisoning, and the resultant
risk for elevated blood lead.
• Methods: City of Milwaukee Health Department Lead Safe Housing Registry (LSHR), Systematic Tracking
of Elevated Lead Levels and Remediation (STELLAR) and Master Property Records (MROP) data sets were
used to relate the risk for elevated blood lead levels with year of home construction, owner versus renter
occupancy and history of home abatement. The relative risk for lead poisoning was calculated for each
characteristics. Year of construction and history of abatement were stratified by age of the child, and
history of abatement was also stratified by type of abatement and time elapsed since abatement.
• Results: A 13% decrease in prevalence (R2 = 0.97) and an 11% decrease in incidence (R2 = 0.93) was
found per 1,000 units abated. An elevated risk for lead poisoning was revealed for pre-1940 units when
compared to post-1940 units (Relative Risk = 5.83, 95% Confidence Interval: 5.57, 6.11) and children aged
0 – 24 months were at the highest risk (RR = 7.91, 95% CI: 7.43, 8.53). The risk for lead poisoning was
greater in non-owner occupied units compared to owner occupied units (RR = 2.02, 95% CI: 1.96, 2.08).
Lead abatement of pre-1940 homes decreased the risk for lead poisoning (RR = 0.69, 95% CI: 0.66, 0.73)
and primary prevention efforts proved to be the most effective (RR = 0.56, 95% CI: 0.53, 0.60). Children at
all age groups had a reduced risk for lead poisoning following abatement, although children 0 – 24
months old were greatest risk (RR = 0.77, 95% CI: 0.72, 0.82). The risk for lead poisoning did not differ
between the first 9 months following abatement and the time following the first 9 months (RR<9 months=
0.72, 95% CI: 0.67, 0.77; RR>9 months =0.65, 95% CI: 0.60, 0.71).
• Conclusion: Primary prevention lead abatement efforts were successful at reducing the risk for lead
poisoning in pre-1940 homes. Using the data collected in our investigation we suggest that future lead
abatement efforts are designed around these characteristics in communities similar to Milwaukee.
ABSTRACT
Kevin M. Smith1, Robert Colla2, Lisa Lien2, Elise Papke1, Steve Gradus1,3, and Sanjib Bhattacharrya1,3
1 UW-Milwaukee, Joseph J. Zilber School of Public Health, 2 City of Milwaukee Health Department - Lead Abatement Program, 3 City of Milwaukee
Health Department – Public Health Laboratories
INTRODUCTION
RESULTS
• Table 1: Pre-1940 homes significantly increased the risk for lead poisoning compared to
Post-1940 homes (RR=5.83, 95% CI: 5.57, 6.11)
• Children 0-24 months old were at greatest risk (RR=7.91, 95% CI: 7.34, 8.93)
• Non-owner occupied homes had significantly increased risk for lead poisoning
compared to owner occupied homes (RR=2.02, 95% CI: 1.96, 2.08)
• Lead Abatement significantly reduced the risk for lead poisoning in Pre-1940 homes
compared to unabated Pre-1940 homes (RR=0.69, 95% CI: 0.66, 0.73)
• Primary Prevention reduced the risk for lead poisoning (RR=0.56, 95% CI: 0.53, 0.60)
• Secondary Prevention increased risk for lead poisoning (RR=1.15, 95% CI: 1.06, 1.25)
RESULTS RESULTS
• Graph 7: The general trend toward an
increased risk for lead poisoning
between 2000 and 2007 did not
deviate from the annual risk following
abatement (compare with Graph 6)
• Primary Prevention efforts did,
however, significantly reduce the risk
for lead poisoning for 1996-1999 and
2008-2011
DISCUSSION
• The annual reduction in lead poisoning prevalence and incidence between 1996 and 2011
was strongly correlated with the number of Pre-1940 homes abated in Milwaukee
• Our investigation shows that Pre-1940 housing and non-owner occupied units were at a
significantly higher risk for lead poisoning compared to Post-1940 homes and owner
occupied units, respectively
• Further, we found that children 0-24 months old are at a significantly higher risk for lead
poisoning than all other age groups and although reduced were at the highest risk for
poisoning following abatement. The increased risk may be caused by a number of factors
such as hand-to-mouth behaviors and increased metabolic demands during this sensitive
stage of development.
• The reduced risk for lead poisoning following lead abatement in the 15 year aggregate data
analysis supports the result that lead abatement was a major component of reducing lead
poisoning rates in Milwaukee, WI from 1996 – 2011
• The short term annual increased risk for elevated BLLs between 2001 and 2006 remains
unexplained and requires further investigation. This may be related to the increased risk
associated with Secondary Prevention as described in the 15 year aggregate and 4 year
range risk calculations. Further, there was no significant difference in risk based on time
following abatement and this also does not appear to account for the increase in risk. It
may be that the overall increase in total number of abatements at this time increased the
likelihood that a case of lead poisoning would occur following an abatement.
• Discovering the cause behind the increased risk for lead poisoning following Secondary
Prevention is important. The children that tested positive for lead poisoning following
Secondary Prevention could be siblings of the children initially found to be poisoned and
may have already had elevated BLLs.
• Primary Prevention efforts in Pre-1940 homes are primarily responsible for reducing the
risk, prevalence and incidence of lead poisoning in this study.
REFERENCES
• Center for Disease Control and Prevention (2014, June 19). Lead – Home Page. Retrieved from:
http://www.cdc.gov/nceh/lead/
• Center for Disease Control and Prevention (2014, October 30). LCDC’s national Surveillance Data (1997-2013).
Retrieved from: http://www.cdc.gov/nceh/lead/data/national.htm
• City of Milwaukee Health Department (2014, September, 12). Lead Poisoning Prevention Data and Reports. Received
from: http://city.milwaukee.gov/Lead-Poisoning-Prevention-Data#.VI88wqecteU
• Cox, D.C., Dewalt, G., O’Haver, R., and Salatino, B. American Health Homes Survey; Lead and Arsenic Findings. U.S.
Department of Housing and Urban Development: Office of Healthy Homes and Lead Hazard Control, April, 2011
• Wheeler, W. (2013). Blood Lead Levels in Children Aged 1-5 Years – United States, 1999-2010. Morbidity and Mortality
Weekly Report, 62, (13), 245-248.Roberts, 2009
• The goal of Healthy People 2020 is to eliminate blood lead levels (BLLs) ≥10 μg/dL and differences in risk
based on race and social class
• In 2012, the Centers for Disease Control and Prevention (CDC) lowered safe BLL standards from 10 μg/dL
to 5 μg/dL
• At present, approximately 535,000 children living in the United States have BLLs ≥5 μg/dL (CDC, 2014)
• The most common sources of lead exposure are lead based paint and contaminated soil near homes and
high traffic road ways (U.S. Department of Housing and Urban Development, 2010)
• Estimates of 37.1 million homes in the United States contain lead based paint (HUD, 2010)
• Nearly 5.7 million homes with children under the age of 6 years old have lead based paint (HUD, 2010)
• In the City of Milwaukee, lead poisoning rates have declined from 31.9% to 3.2% of all children under 6
years old between 1996 - 2011
• In the City of Milwaukee, 16,885 housing units have been abated between 1997 – 2011
OBJECTIVES
Determine the risk for elevated BLLs among children living in:
1. Unabated homes built before 1940 compared with homes built after 1940
a. Adjust for child age: 0 – 24, 25 – 48, 49 – 72 and > 72 months old
2. Non-owner occupied homes compared to owner occupied homes built before 1940 and unabated
3. Homes that were previously abated and built before 1940
a. Adjust for child age: 0 – 24, 25 – 48, 49 – 72 and > 72 months old
b. Adjust for type of abatement: Primary prevention and Secondary prevention
c. Adjust for time following abatement: Within 9 months and after 9 months
y = 2,874.22e-0.00011x
R² = 0.93
y = 5,576.35e-0.00013x
R² = 0.97
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
0 2000 4000 6000 8000 10000 12000 14000
NumberofCasesPerYear
Total Number of Abated Units
Graph 2: Case Reduction of Lead Poisoning per Pre-1940 Unit
Abated (1996 - 2011)
Incidence
Prevalence
• The greatest risk factor for
lead paint exposure is the Year
of Construction of a home
(HUD, 2010)
– Children 6 years old and
younger are at highest risk
for lead poisoning (Wheeler,
2013)
– Populations of low
household income and
minority race have highest
rates of lead poisoning
(Wheeler, 2013)
• Data Sets: STELLAR provided complete records for 186,167 individuals that had at least one blood lead
test in the City of Milwaukee between 1996 and 2011. Blood lead test results were dichotomized into
cases and non-cases. A test was considered a case if the individual ever had a confirmed BLL ≥ 10 μg/dL
or a non-case if they never had a BLL ≥ 10 μg/dL. Records were used from the date first confirmed
elevated or not elevated. Addresses listed in STELLAR were combined with addresses listed in the City of
Milwaukee Master Property Records (MPROP). Year of construction (pre-1940 and post-1940) and owner
occupancy at the address was obtained from MPROP. A history of lead abatement at each address was
obtained from Lead Safe Housing Registry (LSHR) data sets for 16,885 units. Complete records for 21,217
cases and 141,478 non-cases were used to calculate relative risks for each variable between 1996 and
2011. Geographical Information Software was used to make maps of the year of construction for the
homes, and a history of lead poisoning and lead abatement at each home.
METHODS
y = 0.2076x - 409.99
R² = 0.4299
0
1
2
3
4
5
6
7
8
9
10
11
12
13
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012
RelativeRiskRatio
Year
Graph 4: Risk of Elevated BLLs - Pre-1940s Homes
Annual Risk 15 yr Aggregate Risk Annual Regression
y = 0.0058x - 9.8155
R² = 0.0237
0
0.5
1
1.5
2
2.5
3
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012
RelativeRiskRatio
Year
Graph 5: Risk of Elevated BLLs - Non-Owner Occupied Units
Annual Risk 15 yr Aggregate Risk Annual Regression
y = 0.0049x - 8.6599
R² = 0.0049
0
0.5
1
1.5
2
2.5
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012
RelativeRiskRatio
Year
Graph 6: Risk of Elevated BLLs - Prior Abated Units
Annual Risk 15 yr Aggregate Risk Annual Regression
0
0.5
1
1.5
2
2.5
3
3.5
1996-1999 2000-2003 2004-2007 2008-2011
RelativeRisk
Year Range
Graph 7: Relative Risk of Abatement Type (4 Year Range)
Total Abatement Primary Prevention Secondary Prevention
Total 15 yr risk Primary 15 yr risk Secondary 15 yr risk
1996 1997 1998 1999 2000 2001 2002 2003
Relative Risk (95% CI)
Pre-1940 Unit 3.64 (3.32, 3.98) 3.79 (3.42, 4.20) 5.68 (4.78, 6.75) 4.77 (4.04, 5.63) 4.55 (3.87, 5.36) 5.45 (4.51, 6.59) 5.43 (4.45, 6.64) 7.06 (5.51, 9.05)
Non-Owner Occupied 1.73 (1.65, 1.84) 1.76 (1.65, 1.88) 1.89 (1.71, 2.10) 1.85 (1.67, 2.05) 1.64 (1.47, 1.82) 1.77 (1.58, 1.99) 1.77 (1.57, 2.01) 1.70 (1.48, 1.95)
Prior Abatement 1.01 (0.45, 2.25) 0.92 (0.60, 1.41) 1.06 (0.77, 1.47) 0.88 (0.68, 1.13) 1.24 (1.04, 1.48) 1.58 (1.35, 1.85) 1.89 (1.63, 2.19)
2004 2005 2006 2007 2008 2009 2010 2011
Relative Risk (95% CI)
Pre-1940 Unit 8.22 (6.32, 10.69) 5.70 (4.48, 7.25) 7.47 (5.43, 10.26) 5.86 (4.37, 7.86) 8.32 (5.81, 11.92) 8.33 (5.81, 11.95) 5.98 (4.32, 8.29) 5.66 (4.01, 7.98)
Non-Owner Occupied 2.02 (1.75, 2.24) 1.76 (1.51, 2.05) 1.85 (1.53, 2.23) 2.25 (1.85, 2.74) 1.56 (1.28, 1.91) 1.86 (1.49, 2.31) 1.57 (1.23, 1.99) 2.05 (1.56, 2.70)
Prior Abatement 1.69 (1.44, 1.99) 1.59 (1.35, 1.87) 1.42 (1.15, 1.75) 1.22 (0.99, 1.51) 1.18 (0.95, 1.47) 1.08 (0.85, 1.37) 0.83 (0.63, 1.10) 1.21 (0.93, 1.55)
Year Range Abatement
Record
Case
(≥ 10 μg/dL)
No Case
(< 10 μg/dL)
Total Relative Risk 95% CI
1996 - 1999 Total Abated 48 147 195 0.78 (0.61, 1.00)
Primary 41 147 188 0.69 (0.53, 0.91)
Secondary 7 0 7 3.18 (3.13, 3.23)
None 10,982 23,917 34,899
1999 - 2003 Total Abated 443 1,370 1,813 1.38 (1.27, 1.50)
Primary 274 1,135 1,409 1.1 (0.98, 1.23)
Secondary 169 235 404 2.36 (2.1, 2.66)
None 3,897 18,095 21,992
2004 - 2007 Total Abated 482 2,581 3,063 1.45 (1.32, 1.58)
Primary 305 2,036 2,341 1.2 (1.07, 1.34)
Secondary 177 545 722 2.25 (1.97, 2.58)
None 2,094 17,153 19,247
2008 - 2011 Total Abated 303 4,315 4,618 1.06 (0.94, 1.20)
Primary 192 3,441 3,633 0.86 (0.74, 0.99)
Secondary 111 874 985 1.83 (1.52, 2.20)
None 1,175 17,875 19,050
• The incidence rate of lead poisoning showed an overall decrease between 1996 - 2011
• Graph 1: Seasonal variation of incident lead poisoning cases was consistent each year.
• The highest incidence rate of
lead poisoning occurred
during the summer months
(June – October)
• August was frequently the
month with peak incidence
cases
• Graph 2: Prevalence
decreased 13.5% (R2=0.97)
and incidence decreased
10.8% (R2=0.93) per 1,000
Pre-1940 units abated
• Graph 3: Prevalence decreased 13.4% (R2=0.98) and incidence decreased 10.8%
(R2=0.95) per year – approximately 982 units were abated per year between 1997 - 2011
• Map 1: Year of construction for homes in Milwaukee, WI is color coded for Percentage
of Homes Containing Lead-Based Paint (Figure 1)
• Pre-1940 homes are localized to central Milwaukee
• Map 2: Buildings with a record of at least one case of lead poisoning are shown (red) for
the City of Milwaukee, WI from 1996 to 2011.
• Most homes with a record of lead poisoning are Pre-1940 homes
Graph 1:
y = 7627.1e-0.134x
R² = 0.9768
y = 3718.1e-0.108x
R² = 0.9474
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
1996 1998 2000 2002 2004 2006 2008 2010
NumberofUnitsAbated
ChildrenwithElevatedBloodLead
Year
Graph 3: Elevated Blood Lead Levels and # of Units Abated
Pre-1940 Units Abated Total Units Abated Prevalance Incidence
Map 1: Map 2:
Figure 1:
Table 1: Relative Risk for Lead Poisoning - 15 Year Aggregate (1996 – 2011)
Map 3: Map 4: Map 5:
• Spatial representation of new cases of lead poisoning in 1996 (Map 3) before home
abatement (Map 4) and new cases in 2011 (Map 5) following home lead abatement.
• New cases were reduced from 5,816 in 1996 (Map 3) to 381 in 2011 (Map 5)
• Prevention efforts were targeted to non-owner occupied units and low income homes
with children under the age of 6 years living in them
Table 2: Relative Risk for Lead Poisoning – Annual (1996 – 2011)
• Table 2: Annual relative risk for pre-1940 homes, non-owner occupied units and abated
Pre-1940 units are provided for each year between 1996 and 2011
• Graph 4: There was no large change in the risk for lead poisoning from 1996 to 2011 for
pre-1940 homes, overall
• A small increase in risk was noted, but was not significant (slope 0.207, R2=0.43)
• Graph 5: There was no change in the risk for lead poisoning from 1996 to 2011 for non-
owner occupied units
• Annual risk was slightly less than 15 year aggregate risk, but was not significant
• Graph 6: A slight, significant increase
in the annual risk for lead poisoning
was found in units with previous
lead abatement from 2001 to 2006
(2003 had the highest risk value)
• Nearly every year was significantly
higher than the 15 year aggregate
risk from 1999 to 2011 (Compare
Table 1 & Table 2)
Table 3: Relative Risk for Lead Poisoning: Abatement Type – 4 Year Range
• Secondary Prevention efforts
were associated with increased
risk for lead poisoning for all of
the 4 year ranges
• Table 3: Primary Prevention risk
for poisoning was significantly
lower than the Total Abatement
for 1999-2003 only
• Secondary Prevention had the
largest deviation from the 15
year aggregate risk following
abatement for all 4 year ranges
(compare with Table 1)
ACKNOWLEDGEMENTS
• We would like to thank Joyce Witebsky for her help with the GIS mapping, Amy Kalkbrenner for
her advice with statistical analysis, Julie Becker for her assistance with the project, Alice Yan and
Kurt Svoboda for assistance with investigation design and the City of Milwaukee Health
Department Childhood Lead Poisoning Prevention Program for their lead prevention efforts.
Contact Information:
Kevin M. Smith
kmsmith5@uwm.edu
(262) 424-5165
Contact Information:
Kevin M. Smith
kmsmith5@uwm.edu
(262) 424-5165