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

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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