blood lead levels in kansas children
DESCRIPTION
Henri Ménager, MPH Epidemiologist Kansas Environmental Public Health Tracking Program Kansas Department of Health and Environment 68th Annual Kansas Public Health Association Fall Conference Wichita, KS - September 21-22, 2011. Blood Lead Levels in Kansas Children. Background: Lead (Pb). - PowerPoint PPT PresentationTRANSCRIPT
BLOOD LEAD LEVELS IN KANSAS CHILDREN
Henri Ménager, MPHEpidemiologistKansas Environmental Public Health Tracking ProgramKansas Department of Health and Environment68th Annual Kansas Public Health Association Fall ConferenceWichita, KS - September 21-22, 2011
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Background: Lead (Pb)
Highly toxic soft metal It’s heavy (atomic number 82) Widely available in the crust of the earth Cheap Stable Has been used in a variety of products including
Paint Gasoline Ceramics Batteries Pipes (drinking water) Cosmetics Solders Pencils and bullets
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Background: Signs and Symptoms The effects of lead poisoning are often not
apparent until high levels of lead have accumulated in the body.
In children Irritability Learning difficulties Loss of appetite Anemia Weight loss Constipation Fatigue or hyper activity Sleep disorders Abdominal pain Vomiting
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Background: Signs and Symptoms Even at low levels, the long-term effects
can be devastating. That includes: Nervous system and kidney damage Learning disabilities Speech, language, and behavior problems Poor muscle coordination Growth retardation Hearing loss
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How Does Lead Enter the Body? Lead enters the body through the mouth
or nose. Lead is not absorbed through the skin.
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Who is at risk?
Children All children are at risk; especially younger children. The
effects of lead poisoning are more severe in children less than 6 years old.
Children can be exposed to lead during fetal development. Adults in some occupations
Welders Battery plant workers Others
Adults with some leisure activities Minority populations The poor
Sources of Contamination
Sources include Soil Water Lead paint Household dust Imported canned food Traditional remedies Cosmetics Amulets
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How Does Lead Enter the Body? Lead enters the body through the mouth
or nose. Lead is not absorbed through the skin.
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Background: Efforts to Decrease Exposure to Lead
Since 1980, federal and state regulations have contributed to the reduction of lead in the environment and in consumer products. In 1978, the US EPA reduced the amount of lead
allowed in gasoline. In 1986, Congress restricted the use of lead in
pipes, solder, and other household items (Safe Drinking Water Act).
In 1995, the US banned the use of lead in food cans.
Background: Legal
Kansas Statutes Annotated (KSA) 65-1,200 through 65,1,214 authorize KDHE to maintain a database of blood lead tests administered to children and adults
The Healthy Homes and Lead Hazard Prevention Program (HHLHPP) database contains records dating from 1993.
Laboratories must report to KDHE the results of all blood test results (KAR 28-1-18).
Background: Study Purpose
This study focuses on blood tests of children 0 to 17 years old.
This study uses geometric mean as a more appropriate measure to compare entities.
Methods: Data Processing
Data from the STELLAR v. 4.0 database was used to conduct the analysis
all tests results with a sample drawn on or between January 1, 2000 and December 31, 2010 were included in the study
Each record represents a blood test, not an individual
Geometric mean rather than arithmetic mean was calculated using SAS® software version 9.2
Tests with missing or invalid addresses were kept in the analysis as they may constitute a source of bias.
Methods: Geometric mean (gm) Each test value (except for 0) was log-transformed Mean and confidence intervals around the mean of the
log-transformed values were calculated All values were then exponentiated to obtain the gm
and its confidence interval SAS® Proc Survey means was used to compute
standard errors and confidence intervals The gm will be always less than or equal to the
arithmetic mean (am) Generally used to evaluate data sets bound by zero,
data covering several orders of magnitude, and to evaluate ratios and percentage of changes (Costa J, nd)
Distribution of the Test Values
Results
There were 314,092 tests where the blood sample was drawn on or between 1/1/2000 and 12/31/2010
Number of unique children tested: 230,566 including 115,955 males, 109,264 females, and 5,347 with unknown sex.
There were 75024 records (23.8%) with no address and of the remaining about 18% were invalid addresses.
Results
Mean blood lead levels varied with age
Mean Value of Blood Lead Levels by Age Group, 2000-2010
0-2 3-4 5-9 10-12 13-170.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
020,00040,00060,00080,000100,000120,000140,000160,000180,000200,000
2.683.05
2.67
2.081.87
188,886
80,921
36,663
3,655 2,961
Age Groups (Years)
Geo
met
ric
Mea
n
Num
ber
of T
ests
Mean Value of Blood Lead Levels by Age Group, 2000-2010
AGE GROU
PS N
Geometric Means
StdErr
Lower CL
Mean
Upper CL
Mean0-2
188,886 2.68
0.004 2.67 2.69
3-4 80,921 3.050.00
7 3.03 3.06
5-9 36,663 2.670.00
9 2.65 2.68
10-12 3,655 2.080.02
3 2.04 2.13
13-17 2,961 1.870.02
4 1.83 1.92
Results
Mean blood lead levels varied with age Boys were more likely than girls to have
a high mean blood lead level
Mean Value of Blood Lead Levels by Sex, 2000-2010
F M Unk2.602.622.642.662.682.702.722.742.762.782.80
020,00040,00060,00080,000100,000120,000140,000160,000180,000
2.72
2.78
2.67
148,792 158,095
6,199
Sex
Geo
met
ric
Mea
n
Num
ber
of T
ests
Mean Value of Blood Lead Levels by Sex, 2000-2010
Sex N
Geometric Means
StdErr
Lower CL
Mean
Upper CL
MeanF 148,792 2.72 0.005 2.71 2.73
M 158,095 2.78 0.005 2.77 2.79
UNK 6,199 2.67 0.020 2.63 2.71
Results
Mean blood lead levels varied with age Boys were more likely than girls to have
a high mean blood lead level There was a steady decline in mean
blood lead levels over time
Mean (GM) Blood Lead Levels (µg/dL) AmongChildren 0 to 17 Years Old by Year of Sample, 2000-2010
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
00.5
11.5
22.5
33.5
4
050001000015000200002500030000350004000045000
Kansas # of Tests
Geo
met
ric
Mea
n
# o
f Blo
od T
ests
Mean Value of Blood Lead Levels by Year of Blood Sample, 2000-2010
Sample Year N
Geometric Means
StdErr
Lower CL
Mean
Upper CL
Mean2000 8,135 3.48 0.030 3.42 3.54
2001 11,997 3.30 0.023 3.26 3.35
2002 17,563 3.32 0.019 3.28 3.36
2003 30,090 3.09 0.011 3.07 3.11
2004 32,442 3.18 0.011 3.16 3.20
2005 33,261 3.11 0.011 3.09 3.13
2006 31,892 2.98 0.011 2.95 3.00
2007 34,326 2.60 0.009 2.59 2.62
2008 36,505 2.48 0.008 2.47 2.50
2009 38,442 2.43 0.008 2.42 2.45
2010 38,433 2.03 0.006 2.02 2.04
Mean (GM) Blood Lead Levels (µg/dL) AmongChildren 0 to 17 Years Old by District and by Year of Sample, 2000-2010
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
00.5
11.5
22.5
33.5
44.5
5
NC DistrictNE DistrictNW DistrictSC DistrictSE DistrictSW District
Geo
met
ric
Mea
n
Results
Mean blood lead levels varied with age Boys were more likely than girls to have
a high mean blood lead level There was a steady decline in mean
blood lead levels over time Children living in rural counties were
more likely than others to have a high mean blood lead level
Classification of Counties by Population Density*Classification Population Density Number
of Counties
Frontier Less than 6 persons per square mile
31
Rural 6 to less than 20 persons per square mile
38
Densely-Settled Rural 20 to less than 40 persons per square mile
19
Semi-Urban 40 to less than 150 persons per square mile
12
Urban 150 or more persons per square mile
5•*Census 2000•Kansas: Densely-Settled Rural – 105 counties
Mean Value of Blood Lead Levels by Population Density, 2000-2010
Un-known
Densely-Set-tled
Rural
Fron-tier
Rural Semi-Urban
Urban0.000.501.001.502.002.503.003.504.00
020,00040,00060,00080,000100,000120,000140,000
2.42
3.063.55 3.61
2.83 2.6274,895
45,163
9,11225,808
43,321
114,787
Geo
met
ric
Mea
n
Num
ber
of T
ests
Mean Value of Blood Lead Levels by Population Density, 2000-2010
Sample Year N
Geometric
Means StdErrLower
CL Mean
Upper CL
MeanUnknown 74,895 2.42 0.005 2.41 2.43Densely-Settled Rural 45,163 3.06 0.010 3.04 3.08
Frontier 9,112 3.55 0.022 3.51 3.60
Rural 25,808 3.61 0.014 3.58 3.64
Semi-Urban 43,321 2.83 0.009 2.81 2.85
Urban 114,787 2.62 0.005 2.61 2.63
Limitations
24% of the addresses were missing and another 18% had invalid addresses. This could constitute a significant source of bias if one region was more affected than others. However, preliminary analysis let to believe that the problem is evenly distributed throughout the state.
Lack of precision of tests, especially below 5 µg /dL
Several test with different sensitivity and specificity provided the results analyzed
Discussion
Due to efforts at the federal, state, and local levels, elevated blood lead levels are decreasing in Kansas as found in this study
Based on this study, children are more likely to have elevated blood lead levels if they live in rural counties rather than other counties in Kansas. Boys are more likely than girls to have elevated blood lead levels. These findings may have programmatic value
Further studies are warranted to clarify these findings Programmatic interventions to properly collect
addresses, race, and ethnicity information would significantly enhance the quality of the data.
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Discussion: The KS-EPHTP
Kansas Environmental Public Health Tracking Program (EPHTP) New program to improve our knowledge on how
human health is affected by the environment Tracks parallely health hazards, environmental
exposure, and health outcomes Part of the National EPHT Network Currently poised to track: childhood blood lead
poisoning, air emissions, drinking water, selected cancers, hospitalization for asthma and myocardial infarctions, birth defects, carbon monoxide poisoning.
References
Costa ,J. (nd). Calculating Geometric Means. Buzzards Bay National Estuary Program. Retrieved on September 18, 2011 from http://www.buzzardsbay.org/geomean.htm.
CDC (nd). Lead: Topic Home, retrieved on September 18, 2011 from http://www.cdc.gov/lead/
ASTDR (March 2011). Lead. retrieved on September 18, 2011 from http://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=22
Credit
Many thanks to the HHLHPP staff Dr. Farah Ahmed
Environmental Health Officer (KDHE) Thomas Langer, MPA
Bureau of Environmental Health Director (KDHE)
Questions