Blood Lead Levels

for Persons Ages

6 Months-74 Years:

United States, 1976–80

This report provides statistics on the

distribution of blood lead levels for the

civilian noninstitutiona lized population,

ages 6 months-74 years. Blood lead data

collected in the second National Health

and Nutrition Examination Survey

(NHANES 11)are presented by selected

demographic and socioeconomic factors,

and in association with relevant medical

history items and biochemical measures.

Data From the National Health and

Nutrition Examination Survey

Series 11, No. 233

DHHS Publication No. (PHS) 84-1683

U.S. Department of Health and Human

Services

Public Health Service

National Center for Health Statistics

Hyattsville, Md.

August 1984
,

,i

Copyright Information

All materiel appearing in this report is in the public domain and may be

reproduced or copied without permiaeion; citation as to source,

however, is appreciated.

Su~eted Citation

Netional Centsr for Health Statistics, J. L Annest and K. Mahaffey

Blood lead levels for pereons ages 6 months-74 yesra, United States,

1976-80. Vital and Heelth Statistics. Series 11, No. 233.

DHHS Pub. No. (PHS) S4-16S3. Public Health Setvice. Washington.

U.S. Government Printing Office, August 19S4.

tibr~ of conf#maa Cetalqiq in Publication Date

Anneat, Joseph L.

Blood lead Ievela for persona ages 6 nrontha-74 years.

(Data from the National health survey. Series 11 ; 233)

(DHHS publication; no. 84-1683)

Presents data collected in the second National Health

snd Nutrition Examination Survey (NHANES Ii).

Authors Joseph L. Annast end Kathryn Mehaffey.

Includes bibliographical references.

Supt. of Doca. no.: HE 20.620Stl 1/233

1. Lesd-poisoning—United Statea. 2. %lood—Analyaja

and chemistry. 3. Health $urv~-United States.

~ 1. Mahaffey, Kathryn R., 1843- 11. National Center

‘ For Health Statistics (U. S.) 1$1.Tii. IV. Series:

Vkal and health statistics. series 11, Data from the

nationel health survey ; 233. V. Series DHHs, publi.

cation ; no. 84-1683. [DNLM: 1, Laad—Blood—United

Statea—Statistics. W2 A N148vk no. 233]

RA407.3.A347 no. 233 312’.0973s [614.5] 84-600034

[RA1 231 .L4]

ISBN 0-8406-0291 -X

For sale by the Superintendent of Documents, U.S. Qorernment Printing OITlce,Washington, D.C. 20402

. I
National Center for Health Statistics Cooperation of the U.S. Bureau of the Census

Manning Feinleib, M. D., Dr. P. H., Director

Robert A. Israel, Deputy Director

Jacob J. Feldman, Ph. D., Associate Director for Analysis

and Epidemiology

Garrie J. Losee, Associate Director for Data Processing

and Services

Alvan O. Zarate, Ph.D., Associate Director for International

Statistics

E. Earl Bryant, Associate Directorfor Interview and

Examination Statistics

Robert L. Quave, Acting Associate Director for .klanagernent

Gail F. Fisher, Ph. D., Associate Directorfor Program

Planning, Evaluation, and Coordination

Monroe G. Sirken, Ph.D., Associate Director for Research

and Methodology

Peter L. Hurley, Associate Director for Vital and Health

Care Statistics

Alice Haywood, Information Officer

Interview and Examination Statistics Program

E. Earl Bryant, Associate Director

Mary Grace Kovar, Dr. P. H., Special Assistant for Data

Policy and Analysis

Division of Health Examination Statistics

Robert S. Murphy, Director

Catherine E. Woteki, Ph. D., Deputy Director

Sidney Abraham, Chiej Nutrition Statistics Branch

Jean Roberts, Chiex Medical Statistics Branch

Kurt R. Maurer, ChieX Survey Planning and Development

Branch

Rita Weinberger, ChieJ Programming Stafl

Under the legislation establishing the National Heslth Survey, the Public Health Sewice

is authorized to use, insofar as passible, tbe services or facilities of other Federal,

Slate, or private agencies.

In accordance with specifications established by the National Center for Health

Statistics, the U.S. Bureau of the Census participated in the design and selection of the

smrple and carried out the household interview stage of the data collection and certain

puts of the statistical processing.
Acknowledgments

The statistical analyses and preparation for this report

involved the collaborative efforts of a number of statisticians

and health experts. The authors express their appreciation and

gratitude to those who contributed time and effort to this report,

especially the following persons: Robert Murphy, Jean

Roberts, Dr. Mary Grace Kovar, and Gerald Wheeler, who

critically reviewed the manuscript Drs. Joel Kleinman, Mary

Grace Kovar, and Diane Makuc, who provided statistical advice; and Drs. Vernon Houk, Phillip Landrigan, and Jane

Lin-Fu, who provided substantive and medically related advice.

William Crouse provided information and advice on occupational exposure to lead. Drs. Robert Casady and Andrew

White assisted in the statistical analysis, preparation, and review of appendix II, and Dr. James Pirkle assisted in the statistical analysis of the chronological trend in blood lead levels

and wrote an earlier version of appendix IV.

Also, the authors appreciate the diligence of the field and

laboratory personnel, especially Brenda Lewis, Elaine Gunter,

and Wayman Turner, who coordinated the collection, shipping,

and processing of blood samples, and Dr. Dennis Cox, who

supervised the blood lead assessments in the toxicology laboratory at the Centers for Disease Control.

11!
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Human exposure toleadinthe U.S. population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Public health concerns aboutexposure tolead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Factors associate~ with exposure tolead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Highlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Survey design andmethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SecondNational Health and Nutrition Examination Survey(NHANE SII)sampledesign and theleadsubsample . . . . . .

Quality contiol adlaborato~ procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Statistical methods . . . . . . . . . . . . ........ ........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead levels byage, race, and sex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead levels by income anddegree ofurbanization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Elevated blood lead levels in children . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead levels ofchildren in association with other selected factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The effects ofalcohol consumption, smoking, andoccupationon bloodleadlevels ofmen andwomen . . . . . . . . . . . . . . . . .

Chronologicaltrend inblood leadlevels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The associationof erythrocyte protoporphyrin with bloodleadlevel andiron status.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Listofdetailedtables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendixes

I. Statistical notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

II. Statistical analysis oftheeffects ofanalytic erroron national estimates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

III. Demographicandsocioeconomic terms anddietary andmedicalhistory items. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IV. Statistical malysis oftiechronolo#cd trend kNHWES~bld lead levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

List of text figures

1.

2.

3.

4.

5.

6.

7.

8.

9.

Blood leadlevels byraceanci age: Utited Stites, 1976.80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood leadlevels bysexmd age: United States, 1976.80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead levels of children 6 months-5 years by annual family income United States, 1976–80 . . . . . . . . . . . . . . . . . .

Blood lead levels of children 6 months-5 years by race and degree of urbanization United States, 1976-80 . . . . . . . . . .

Blood lead levels of children 6 months-5 years in large urban areas by race and Iocatiom United States, 1976–80. . . . .

Blood lead levels of children and youths 6 months-17 years by education of the head of household, race, and age: United

States. 1976.80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead levels ofpersons ages 18-74yeas bysex, deNeeof potential occupational exposure tolead, alcohol congumption, andsmoking status: United States, 1976–80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chronological trend in average blood lead levels for persons 6 months-74 years: United States, 1976-80 . . . . . . . . . . . .

Reduction in mean blood lead levels for persons 6 months-74 years by race, sex, and age United States, 1976-80 . . . .

...

111

1

1

1

1

3

4

4

4

5

7

7

7

9

11

12

13

15

18

19

22

39

47

54

56

7

8

9

9

9

11

12

13

14

v
10. Percent of persons 6 months-74 years with erythrocyte protoporphyrin values of 30 Pg/dl or more by blood lead and

iron status: United States, 1976–80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

11. Cumulative percent distribution of erythrocyte protoporphyrin levels for persons 6 months–74 years by blood lead levels

andiron status: United States, 1976–80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

List of text tables

A. Number of children examined, geometric mean, and standard deviation of blood lead levels and percent of children 1–5

years withvalues 2z30~g/dlby race and age: United States, 1976 -80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

B. Percent and standard error of the percent of children 6 months–5 years with blood lead levels above selected levels, by

race, sex, annual family income, and degree of urbanization: United States, 1976–80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

C. Pearson correlation coefficients between the average blood lead levells for 6-month periods and the total lead used in gas~

line production per 6 months and the averages of the coefficients, by selected characteristics: United States, 1976-80 . . . 14

D. Number of examined children 6 months-5 years, estimated population, percent of estimated population, and standard

error of the percent by selected erythrocyte protoporphyrin levels, according to selected blood lead levels: United States,

1976 -80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Symbols

--- Data not available

. . . Category not applicable

Quantity zero

0.0 Quantity more than zercl

but less than 0.05

z Quantity more than zerc)

but less than 500 wher(; numbers

are rounded to thousands

*

Figure does not meet standards of

reliability or precision

# Figure suppressed to comply with

confidentiality requirements

vi
Blood Lead Levels

for Persons Ages

6 Months–74 Years

by Joseph L. Annest, Ph. D., Division of Health Examination

Statistics, National Center for Health Statistics,a and Kathryn

Mahaffey, Ph. D., Division of Standards Development and

Technology Transfer, National Institute for Occupational

Safety and Health

Introduction

Human exposure to lead in the U.S. population

The exposure to lead from environmental sources is a

public health concem.1 National estimates of blood lead levels,

a common index of lead exposure, for examinees from the second National Health and Nutrition Examination Survey

indicated detectable levels of lead throughout the U.S. population.2-4 A more detailed presentation and comprehensive documentation of national estimates of blood lead levels pertaining

to selected demographic and socioeconomic factors, medical

history items, and biochemical measures is presented in this

report. Quality control and laboratory methods are described

and the magnitude of the effect of measurement error on national estimates is evaluated. Details of the statistical analysis

of a time trend in national estimates of blood lead levels are

presented. Important findings and conclusions from the previous papers2-4 are highlighted and referenced. Statistics on

the distribution of blood lead levels in population subgroups

serve (I) to describe the variation in blood lead levels in the

U.S. populatio~ (2) to establish baseline estimates for future

studies to monitor changes in exposure to lead overtire% (3) to

provide normative information for use in health policy decisions

and for setting standards for the regulation of lead in food,

consumer products, gasoline, air, and water and (4) to determine target populations for lead screening programs.

Public health concerns about exposure to lead

The toxic effects of prolonged exposure to high levels of

lead are known. 1 Children with very high blood lead levels

(greater than 70 micrograms per deciliter Qq#dl) of whole

blood) can suffer permanent renal and neurological damage. In

severe cases, lead poisoning can cause encephalopathy, convulsions, coma, and frequently death.5 Among survivors of severe lead poisoning, significant mental retardation frequently

occurs.6 Health effects of lower levels of lead exposure are

more subtle, but significant, including impaired hematopoiesis

artd neuropsychological deficits in children.T-g

Chronic occupational exposure to lead has been shown to

cause anemia and peripheral neuropathy; the extent and severity of these effects correlate with observed blood lead levels. 10

However, workers with long-temn exposure can have an elevated body-burden of lead, but have blood lead concentrations

aNow with the Chronic Disease Division, Centersfor Disease Control.

in the upper portion of the distribution observed among the

nonoccupationally exposed population. Occupational lead exposure has also been associated with central nervous system

dysfimction and renal impairment, resulting in elevated death

rates from kidney disease. 11Lead may also cause depressed

sperm counts. 12

Lead has toxic effects and serves no apparent usefid function in the human body. 13The detrimental effects of detectable

levels of lead in the body area public health concern, especially

in young children during critical periods of physical growth and

neurological development. In light of these concerns, this paper

focuses on the distribution of blood lead levels in the general

population, with emphasis on demographic, socioeconomic,

and behavioral associations for young children and other selected population groups.

Factors associated with exposure to lead

The assessment of human variation in blood lead levels

depends on an understanding of the environmental sources of

lead and the means by which lead enters the body. The most

common vehicles for transfer of environmental lead to humans

are air, food, water, dus~ dim and lead-based paint. The most

common means of entry into the body are ingestion and inhalation. In the mid-1970’s most of the environmental lead in

the United States originated from leaded gasoline combustion,

industrial emissions, lead-soldered side seam cans for food,

and flaking paint chips from houses built before 1950.1

Young children are particularly likely to have additional

lead exposure from paint, dust, and dirt because of frequent

hand-t~mouth activity and the tendency to eat unusual substances (pica).s Exposure to lead from paint almost invariably

comes from eating lead paint chips or broken, lead-impregnated

plaster found in old dilapidated houses. The degree of exposure

to lead from dust and dirt depends on the environment in which

children reside or play. Sucking dirty fingers, eating with unclean hands, consuming food items dropped on the ground, and

mouthing toys or other objects coated with dust or dirt are common practices among toddlers and young children.

Adults also absorb lead from dust and dim, for example,

inhaling lead dust and fumes and ingesting lead dust from

fingers, food, and cigarettes.14,15The risk of lead toxicity is

particularly high for those who work in secondary lead smelters,

storage batte~ plants, scrap metal handling, car repair shops,

1
and industries producing lead pigments and lead-soldered

stained glass.

Lead usually enters the body by ingestion or inhalation, In

young children, clinical studies have shown that approximately

40 to 50 percent of the lead ingested is absorbed from the gastr~

intestinal tract, while adults absorb about 5 to 10 percent this

way. 16The rate of absorption of airborne lead in relation to age

is not as clearly understood. Although percent retention of inhaled lead is influenced greatly by particle size, clinical studies

suggest that, in general, 20 to 40 percent of inhaled lead will be

deposited in the respiratory tract.17 However, because of the

higher metabolic rates and greater physical activity of children,

it is estimated that with comparable exposure, children inhale

two to three times as much airborne lead per unit body weight

as ndults. 1s

2
Highlights

The following conclusions are derived from data collected

by the National Center for Health Statistics:

●

●

●

●

Analysis of a chronological trend in the data indicated that

average blood lead levels in the U-nited States declined

approximately 37 percent (5.4 pg/dl) from February 1976

through February 1980. The results of the trend analysis

suggestthat the most likely explanation for this decline is a

reduction in lead usage in gasoline during the same

period.

National estimates indicated that at the survey midpoint

(March 1, 1978) 4.0 percent, or approximately 675,000

of the children 6 months-5 years of age had elevated

blood lead levels (30 or more micrograms per deciliter of

whole blood). The estimated number of children with elevated blood lead concentrations was two to four times

higher than previously predicted by data obtained from the

community-based lead poisoning prevention programs.

The percent of children 6 months-5 years of age with elevated blood lead levels was significantly higher for black

children (12.2 percent) than for white children (2.0 percent). Almost one-fifth (18.5 percent) of black children

from low-income families had elevated blood lead levels.

About one-fifth (18.6 percent) of black children living in

the central city areas of large cities with 1 million or more

population had elevated blood lead levels.

A substantial number of children with elevated blood lead

levels (30 pg/dl or more) had erythrocyte protoporphyrin

(EP) levels less than 50 #g/all-a finding of importance to

lead screening programs.

●

●

●

●

●

Among people 6-17 years of age, mean blood lead levels

decreased across successive age groups until late adolescence. Overall, an estimated 0.5 percent of this age group

had elevated blood lead levels.

For people 18-74 years of age, the mean blood lead level

of men substantially exceeded that of women.

Accounting for age, race, smoking, and alcohol consumption, there was a significant positive association between

average blood lead level and the degree of potential exposure to lead at the workplace for male and for female

workers.

Approximately 4.1 percent of U.S. children 6 months-5

years of age were reported as having been tested for lead

poisoning with more black children (12.5 percent) being

tested than white children (2.7 percent). About one-fourth

(24.6 percent) of black children living in large urban areas

with 1 million or more population were reported as having

been tested.

Some children repeatedly ingest nonfood substances (a behavior called pica) that may be contaminated with lead.

During the survey period, 8.1 percent of U.S. children 6

months-5 years of age had a history of eating unusual

substances, such as clay, starch, paint or plaster, and dh-t.

History of pica was more common for black children than

white children and for children living in households with

annual family incomes less than $10,000 than for children

in families with higher incomes.

3
Survey design and methods 

Second National Health and Nutrition 

Examination Survey (N HAN ES I I) 

sample design and the 

lead subsample 

The cross-sectional survey was conducted from February 

1976-February 1980, with a probability sample of 27,801 

persons residing in 64 areas of the United States.19 National 

estimates obtained from the data for the 64 areas are representative of the U. S. civilian noninstitutionalized population (including Alaska and Hawaii) 6 months-74 years of age. Certain subgroups of special interest for nutritional assessment 

were deliberately oversampled. These included children 6 

months-5 years, adults 60-74 years, and persons living in lowincome areas. The survey included interviews to obtain demographic, medical history, and nutritional information. Medical 

examinations and numerous laboratory measurements from 

blood and urine specimens, including blood lead determinations, were also included. 

Of the 27,801 sample persons, 16,563 were asked to provide blood specimens for lead level measurements; they included all children 6 months-6 years and a half sample of persons 7-74 years. Blood specimens for assessment of lead 

concentrations were not obtained on approximately 39 percent 

of these persons, usually because of nonresponse at various 

stages of the survey. A detailed description of the investigation 

of sample persons with missing blood lead data is given in appendix I. The results show no evidence of bias in that nonresponse was distributed uniformly by race, sex, degree of urbanization (of place of residence), and annual family income. 

The total nonresponse in the lead subsample was greater for 

young children 6 months-5 years (5 1 .O percent) than for those 

6-17 years (28.6 percent) or 18-74 years (35.7 percent). 

However, differences in nonresponse by age are taken into 

consideration in the weighting and poststratification adjustment processes. (See appendix I.) 

Blood lead levels were determined for blood specimens 

from 10,049 examinees. Capillary blood was obtained from 

113 children ages 6 months-7 years (mostly from children 

under 4 years old) by fingerstick (pricking of the fingertip); 

venous blood was obtained by venipuncture from the remaining 

9,936 examinees. Although careful procedures were used during the fingerstick process, the potential for contamination 

during the capillary blood collection existed.20 Preliminary 

analysis of the NHANES II data suggested that including the 

capillary blood lead data in this analysis would introduce bias 

in the estimates of mean venous blood lead levels in children. 

Overall, for children 6 months-5 years, the unweighted mean 

blood lead level for those receiving fingersticks was observed 

to be approximately 6.0 ,ug/dl higher than for those receiving 

venipunctures. This difference was observed for black and 

white children. Three additional examinees had elevated 

venous blood lead levels (76.0, 80.0, and 90.0 pg/dl), which 

were considered to be the result of atypically high exposure to 

lead, Therefore, the blood lead values of persons receiving 

fingersticks and of the three venipuncture cases with extreme 

lead exposure were excluded from further analysis. (A description of these excluded blood lead values is given in appendix I, 

table VII.) Thus, in this report, national estimates are based on 

data obtained on 9,933 NHANES II examinees with venous 

blood lead levels ranging from 2.0-66.0 pg/dl. 

Quality control and laboratory procedures 

NHANES II participants were examined at mobile examination centers that were set up at each of the 64 sampling 

locations so that the environment and equipment would be standard and methods of blood collection and specimen processing 

would be uniform. 

Venous blood specimens were collected in either 5- or 

7-milliliter (ml) ethylene diamine tetraacetic acid (EDTA) 

lavender-top Vacutainer tubes (Vecton-Dickinson Co., Rutherford, NJ). After the blood and anticoagulant were mixed, each 

sample was placed under a laminar flow hood that provided 

class-l00 air (that is, air containing less than 100 particles per 

cubic meter of less than 0.5 micrometer diameter) to minimize: 

contamination by dust particles. An aliquot was poured into L 

Mini-Vial (Packard Instruments, Downers Grove, Ill.). Theqe 

aliquots (and those in capillary tubes) were then frozen wi.*t 

1 hour after collection and were shipped in Dry Ice to the Centers for Disease Control (CDC) for analysis. Samples remained 

frozen until analyzed. All tubes and vials used for collection 

and storage were from production lots that had been screened 

previously at CDC for lead contamination. 

All laboratory determinations of blood lead levels from 

these blood samples were performed by the Clinical Chemistry 

Division, CDC, Atlanta, Georgia, and financed by the Division 

of Nutrition, Bureau of Foods, Food and Drug Administration, 

Cincinnati, Ohio. Descriptions of the material, methods, and 

quality control procedures are presented in detail elsewhere.21 *22 

Brief descriptions of the laboratory procedures and quality control methods are presented in the following paragraph to demonstrate the precision and accuracy of the measurements. 
Lead concentrations of sample and control specimens 

were determined with a modified Delves cup atomic absorption 

micromethod .23y24 A Perkin-Elmer Model 360 atomic absorption spectrometer equipped with a three-slot burner, microcombustion assembly, lead hollow-cathode lamp, and deuterium 

arc background corrector was used. The instrument parameters 

and settings were as follows: wavelength, 283.3 nanometers; 

lamp current, 10 milliamperes; slit, 0.7 nanometers (normal 

mode); signal, TC- 1 (time constant-l); and operating mode, 

AB S (absorbance). The reagents and calibration procedures 

were the same for analysis of all blood samples. Contamination 

in the laboratory was minimized by handling blood samples 

under hoods that provided class-l00 air. 

Blood specimens were analyzed in duplicate, using IO-@ 

sample volumes. When replicate absorbance values differed by 

more than 0.025 absorbance or the difference between calculated lead concentrations for duplicates was greater thair 

7&dl, analysis was repeated. The results of the repeat analysis were reported. Out of the approximately 10,000 whole 

blood lead samples, 458 were repeated because duplicate measurements differed by more than 7 ,ug/dl. Thirty-six of these 45 8 

had duplicate measurements that differed by more than 25 

&dl and clearly were cases of a problem such as a microclot, 

a pitted cup, or a misaligned cup. The remaining 422 samples 

had a difference between duplicate determinations greater than 

7 &dl either from one of the previously mentioned sources or 

from random sources of error typically associated with analytical procedures (for example, pipetting and instrument noise). 

Two quality control systems, using bovine whole blood 

pools, were used, (Blood used in preparation of quality control 

samples was collected by venipuncture from cows administered lead nitrate capsules orally.) These two systems were 

(1) “bench” quality control samples that the analyst inserted 

and measured two-four times in each analytic run for technical 

evaluation on the day of analysis, and (2) “blind” quality control specimens placed in vials, labeled, and processed to be 

indistinguishable from regular NHANES II samples. The results were decoded and reviewed by the quality control supervisor. At least one “double blind” sample was randomly inserted and analyzed in duplicate with 20 NHANES II samples 

(in a given run). If the average of replicate values of either bench 

or blind quality control samples fell outside their respective previously established 95 percent confidence limits, the run was 

repeated. 

Bench quality control samples were collected in 5-ml 

lavender-top EDTA Monoject (Sherwood Medical Industries, 

St. Louis, MO) vacuum collection tubes (from the same production lots as those used to collect NHANES II samples) and 

stored at -20” C; approximately 100 tubes were drawn at each 

sampling. Two levels of bench pools were maintained: one containing a lead concentration within the normal range, the other 

an abnormally high level (greater than 30 ,ug/dl). New pools 

were prepared at approximately 6-month intervals, allowing a 

2-month overlap between new and old pools to insure standardization of measures over time. 

The blind quality control system was based upon two large 

pools that were prepared in sufficient amounts to cover the 

entire duration of the survey. Because of initial technical difficulties in labeling the blind specimens (to be indistinguishable 

from the NHANES II specimens), the two blind pools were 

analyzed with the NHANES II sample specimens collected 

from March 1977 through the end of the survey. The lead levels 

were in the low normal range for one pool and near the decision 

point at 30 ,ug/dl for the other pool. Because results showing 

concentrations equal to or greater than 30 &dl were phoned to 

the personal physician of the examinee, an elevated blind pool 

could not be used. The blood was collected in sterile 500-ml 

bottles containing 1.5 milligrams per milliliter (mg/ml) K,EDTA 

as the anticoagulant. Blood from several bottles was pooled, 

mixed, and dispensed into vials identical to those used in the 

field to process the examinees’ blood lead samples. The vials 

were labeled with pseudopatient numbers corresponding to 

each geographic location and stored at -20” C. 

The normal blind pool with a mean of 13.7 ,@dl had a 

standard deviation (SD) of 2.2 pg/dl (0.022 parts per million 

(ppm)) while the high blind pool with a mean of 25.5 ,ug/ol had 

an SD of 3.2 pg/dl (0.032 ppm). The coefficient of variation 

(that is, the standard deviation expressed as a fraction of the 

mean blood lead level for a given pool) for the bench quality 

controls having blood lead levels of 30.0 ,ug/dl or more ranged 

from 7.0 to 15.0 percent.21 

Further information on the quality control data and an 

evaluation of measurement error are presented in appendix II. 

The potential effects of misclassification error on national prevalence estimates of elevated blood lead levels (30 &dl or more) 

are evaluated. The statistical analysis indicates that accounting 

for measurement error in blood lead assessments could reduce 

the estimate of overall prevalence of elevated blood lead levels 

up to 24 percent. 

Statistical methods 

Statistics are provided for population subgroups defined 

by factors previously reported to be associated with blood lead 

levels in the general population.2j3J8525-27 Categories were defined to provide stable popul.ation estimates and to test significant differences between population subgroups of importance for public health programs concerned about exposure to 

environmental lead. Statistics are not presented for further crossclassifications or smaller breakdowns of the data because of 

unreliability of the estimates or their standard errors. 

The statistical analysis of the weighted NHANES II blood 

lead data took into account the complex survey sample design; 

that is, the clustering and oversampling of selected groups.1g 

The variances were computed using SESUDAAN, a computer 

program based on a Taylor linearization procedure that provides consistent estimates of standard errors of means and of 

proportions. 28 The analysis of blood lead levels as a continuous 

variable was carried out using SURREGR, a regression program 

that provides consistent estimates of standard errors for regression coefficients. 2g The analysis of blood lead level as a cateI 

gorical variable was carried out using the variance-covariance 

matrix produced by SURREGR as input to GENCAT, a program for generalized least-squares categorical data analysis.30y31 

All differences stated in the text were conducted using the 

variance-covariance matrix. Tests of significance were con5 
ducted using a probability level of 0.05 unless otherwise indi- children, youths, and adults. In addition, statistics on blood

cated. Further details on statistical tests and measure of vari- lead levels are given by education of the head of the household,

ability are in appendix I. history of pica, and history of tests of lead poisoning for~chilIn the next section, distributions of blood lead levels in the dren, and by occupation, history of smoking, and alcohol conU.S. population are presented by age, race, sex, annual family surnption for adults. The definitions of terms and variables and

income, and degree of urbanization (of place of residence) for the history questions are in appendix III.
Blood lead levels by age, race, and sex

Average blood lead level estimates for the U.S. population

differ substantially with respect to age, race, and sex (figures 1

and 2 and tables A and 1-4). Differences in blood lead levels

associated with these factors in the general population were the

result of dhlerences in exposure to environmental sources of

lead or in the absorption, retention, or excretion of lead in the

blood, or both. However, the relative contributions of these

factors to blood lead level in the general population have not

been determined.l

For young children 6 months–5 years, mean bIood lead

levels were significantly higher for black children than for white

children (figure 1,table 4). The higher blood lead levels in black

children than in white children have been noted eIsewhere.32

Accounting for dfierences associated with race, the differences

between means with respect to age and sex were not statistically

significant. The lack of association between age and blood lead

level for children 6 months-5 years of age is somewhat of a surprise because otier studies in the United States32and Europe33,34

indicate a peak in average levels at 2 to 3 years of age.

Overall for children and youths 6–17 years, mean blood

lead levels decreased significantly as age increased (figure 2).

A similar decline in blood lead levels from 6 years to later

adolescence has been noted in the United Kingdom.33,34Accounting for the effects of age, race and sex differences were

significant. Generally, as age increases, the difference in mean

blood lead levels between boys and girls increases, with those

of boys consistently higher than those of girls. The average

blood lead levels are also significantly higher for black persons

than for white persons in this age range.

For adults 18–74 years, there were significant differences

in blood lead levels associated with age, race, and sex. The sex

difference was the most pronounced, with the mean blood lead

level consistently higher for men than for women (figure 2).

Accounting for differences related to sex and age using regression analysis, blood lead levels were, on the average, higher for

black adults than for white adults (figure 1).

Blood lead levels by income and

degree of uhanization

The associations of family income and of the degree of

urbanization with blood lead levels were generally consistent

across all ages with higher mean blood lead levels among the

o

s 17

.= 1- \ Black ~

---

--

--- __=

, ,

z

0

I

I I 1 I I I 1

0 10 20 30 40 50 60 70

Age in years

Figure 1. Blood lead levels by race and age: United States, 1976-80

7
Table A. Number of children examined, geometric mean and standard deviation of blood lead levels and percent of children 1-5 years with

values >30 pgidl, by race and age: United States, 1976–80

Standard Estimated Standard

Number Geometric deviation of percent with error of

Race and age examined meanl the mean~ PbB >30 pg/dll the percent

——

White

I year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 14.1 1.49 2.8

2 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.04

296 14.3 1.45 2.8 1.00

3 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 14.3 1,44 2.9 0.68

4years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434. 1:3.8 1.44 1.8 0.64

5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453 13.9 1.40 0.8 0.37

Black

l year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 20.4 1.51 18.2 6.43

2 yeara . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 20.5 1.45 16.8

3 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

3.66

2’1.3 1.47 18.1 3.82

4 yeara . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 20.0 1.39 11.1

5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.58

101 1[3.2 1.41 4.6 ‘1.47J

1Estimated from the weighted NHANE.5 II data obtained on examinees with blood specimens drawn by venipun~ture,

NOTE: ? = equal to or greater than.

~gldl = micrograms per deciliter.

c.-

18 Males

11

~*

------

17 // --

\

~ .6 ---

16 // ---

0

15 0

14 0

‘\ /

13 \/

12

,~

11

10 Females

0 ~~~1

o 10 20 30 40 50 60 70

Age in years

Figure 2. Blood lead levels by sex and age: United States 1976-130

poor than the more aflluent and for those in urban than in rural

areas (tables 5–7). These associations were most pronounced,

however, in children ages 6 months-5 years (figures 3-5). Accounting for variation in blood lead levels associated with age,

sex, and race by regression, there was a statistically significant

inverse relationship between mean blood lead levels in children

and family income. Similar analysis indicates that mean blood

lead levels were higher for children living in large urbanized

areas than for those living in smaller urban or rural areas.

Mean blood lead levels for black children were significantly higher than those for white children across all three income

groups and the two urban groups. A similar racial difference in

mean blood lead levels was observed in the rural group (figure

4), but it was not statistically significant, probably because of

the relatively small number of rural black children in the sample.

This consistent difference between black and white children

suggests that higher blood lead levels for black children are not

filly explained by exposure to lead-laden sources commonly

identified with children living in deteriorating housing in the

inner cities (urban lead belt). These findings are consistent

,with those of other studies regarding this racial difference.sz~ss,sb

Within the central cities of large urban areas with 1 million

or more population, the mean blood lead level of black children

was significantly higher than that of white children. Other

studies18 indicate that exposure to lead in central city children

may be associated with socioeconomic factors. It is estimated

from the NHANES II data that 43 percent of black children

com]pared with 22 percent of whhe children living in the central

city areas were from households with annual family incomes

under $6,000 during the year preceding the time of interview.

In 1978 (the midpoint of the survey was March 1, 1978), the

inco]me level of $6,000 was near the poverty threshold for a

8
** r I

95-percent confidence

intervals

Less than $6,000-

$6,000

$15,000

$14,999 or more

Figure 3. Blood lead levels of children 6 months-5 yeers by race

and annual family income United Statea, 1976-80

c.-

Izl White

I

95-percent confidence

intervals

24

20

16

12

8

4

0

Urban: Urban: Rural

1,000,000 fewer than

persons 1,000,000

or more persons

Figure 4. Blood Iced levels of children 6 months-5 years by race

and degree of urbanization: United States, 1976-80

u White

❑:~:~~ ✎

Black

I

95-percent confidence

intervals

28 r

Central city Non-central city

Figure 5. Blood lead IaveIs of children 6 months-5 years in large

urban arees by race and location: United States, 1976-80

family of four as determined by the U.S. Bureau of the Census.sT

Mean blood lead levels of black children livingin the central

cities were observed to be higher than those of black children

living in urban areas outside the central cities and rural areas,

respectively. These differences were neither statistically significant nor reliable because of the small number of black children

in the sample who were living outside the central city.

Attempts to cross-classifi by degree of urbanization and

income using the NHANES II data resulted in samples too

small to provide reliable estimators. For example, while it

would have been of interest to determine whether the association

between race and blocd lead level differed between various

degrees of urbanization by income groups, the number of exarninees within such groups was too small.

Elevated blood lead levels in children

The consistent difference in mean blood levels between

black and white children ages 6 months-5 years and the higher

blood lead levels among children from low-income families or

residing in large urban areas was also apparent from the percent

of children with elevated blood lead levels (that is, equal to or

greater than 30 Kg/all)(table B). In accordance with Centers for

Disease Control (CDC) guidelines publishedin1978~830 pg/

dl is the cutoff used in many of the community-based lead

screening programs for referring children for further clinical

diagnostic evaluation.

Based on the CDC guidelines (30 pg/dl or more), an analysis of NHANES II data indicates that 4.0 percent or approx9
Table B. Percent and standard error of the percent of children 6 months-5 years with blood lead levels above selected levels, by race, sex,

annual family income, and degree of urbanization: United States, 1976-80

All racesl White Black

20 pg/dl 25 p,g/dl 30 pg/dl 20 p.g/dl 25 pg/dl 30 pg/dl 20 pg/dl 25 pg/dl 30 Pg/dl

Demographic variable or more or more or more or more or more or more or more or more or more

Both aexes . . . . . . . . . . . . . . . . . . . . . . .

Boys . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Girls . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Annual family income

Under $6,000 . . . . . . . . . . . . . . . . . . . . .

$6>000-$14,999 . . . . . . . . . . . . . . . . . .

$15,0000 r more . . . . . . . . . . . . . . . . .

Degree of urbanization of place

of residence

Urban, 1 million persons or more . . . . .

Central ity. . . . . . . . . . . . . . . . . . . . .

Non-central city . . . . . . . . . . . . . . . . .

Urban, fewer than 1 million persons. . .

Rural . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Both sexes, . . . . . . . . . . . . . . . . . . . . . . .

Boys . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Girls . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Annual family income

Under $6,000 . . . . . . . . . . . . . . . . . . . . .

$6,000-$ 14,999 . . . . . . . . . . . . . . . . . .

$15,0000 r more . . . . . . . . . . . . . . . . . . .

Degree of urbanization of place

of residence

Urban, 1 million persona or more . . . . .

Central ity. . . . . . . . . . . . . . . . . . . . .

Non-central city . . . . . . . . . . . . . . . . .

Urban, fewer than 1 million persona. . .

Rural . . . . . . . . . . . . . . . . . . . . . . . . . . .

24,5

25.6

23.4

45.5

26.4

13.4

36.2

48.2

27.0

28.0

11.5

2.2

2.6

2.2

3.2

2.8

1.9

3.5

4.1

3.9

4.3

2.6

9.1

9.7

8.4

21.8

8.8

4.4

14.9

22.2

9.2

9.5

4.2

1.0

1.3

0.9

2.7

1.1

1.3

2.1

3.4

2.0

1.7

1.4

4.0

4.4

3.5

10.9

4.2

1.2

7.2

11.6

3.7

3.5

2.1

0.5

0,7

0.5

1.4

0.7

0.4

0.7

1.9

0.8

0.6

0.9

Percent of children2.3

18.1 5.5 2.0

‘19.4 6.0 2.1

‘16.6 4.9 1.B

:33.1 14.0 5.9

:21.1 5.6 2.2

‘10.5 3.3 0.7

;28.3 9.8 4.0

:35.2 12.1 4.5

:25.3 8.8 3.8

:20.6 5.7 1.6

9.5 2.7 1.2

!Standard error of the percent

2.3 O.B 0.3

2.6 1.0 0.5

2.3 1.0 0.4

4,0 2.7 1,3

3.0 1.1 0.5

2.0 1.1 0.3

4.4 2.3 0.7

6.7 3.4 1.9

4.1 2.4 0.8

4.1 1.3 0.4

2.3 0.8 0.5

52.2

48.5

56.2

61.0

51.1

36.5

59.1

63.3

44.9

51.4

29.9

3.B

4.7

4.0

4.3

4.2

6.4

4.9

5.8

8.0

5.6

11.1

24.5

24.8

24.1

34.2

23.6

B.O

28.5

32.7

‘14.1

22.2

*1 9.4

2.9

4.3

4.3

5.9

2,8

3.1

3.5

6.2

“3.8

4.5

*1O.1

12.2

13.4

1,0.9

1B.5

1’2.1

2.8

15.2

18.6

“3.3

10.2

“10.3

1.5

2.0

12.4

3.6

1.9

1.2

1.5

2,8

‘1.4

2.4

*5.3

1Includes data for races not ahown separately.

‘The one child (a black male, family income under $6,000, in a rural area) with an excessivel’f high blood lead level (76.IJ pg/dO waa excluded. This exclusion has ~

negligible effect on the national eatimatea ahown here.

3Estimated using data on blood lead levels determined from specimens drawn by venipuncture.

NOTE: pgldl = micrograms per deciliter.

imately 675,000 U.S. children 6 months-5 years of age had

elevated blood lead levels in the late 1970’s. (This estimate

was two to four times higher than previously predicted from

data obtained in the CDC lead poisoning prevention programs

for children 1-5 years. )39 Among children of this age, 12.2

percent of black children compared with 2.0 percent of white

children had blood lead levels of 30 ~gldl or more. This dhTerence was significant for boys and for girls. The percent with

elevated blood lead levels was observed to be slightly higher in

boys than girls, but this dflerence was not statistically significant

at the 0.05 level of probability.

The proportion of children with elevated blood lead levels

decreased with increased family income. This relationship was

significant for black :,nd for white children. The highest percent

of elevated blood lead levels (18.5 percent) was found among

black children from low-income families. For both white and

black children, the percent of persons with elevated blood lead

levds was lowest in the highest income group.

For children living in the central cities of large urban areas

with 1 million or more population, the percent of children with

elevated blood lead levels was significantly higher for black

than for white children. Even in the smaller urban (less than 1

million persons) and rural areas, more than 10.0 percent of

black children was observed to have elevated blood lead levels

compared with less than 2.0 percent for white children. Caution should be exercised in interpreting racial differences in

rural areas because of the relatively small number of examined

persons (42 cases) in the estimation cell for rural black children.

Recently, concern has been expressed that a cutoff of

30 ~gldl may not provide a reasonable margin of safety for

children 5 years of age or younger. Studies suggest that even at

blood lead levels between 10 to 20 ~g/dl, lead can impair in10
tracellular functions40’41and is toxic to the developing brain

and nervous system.42’43Detection of impairment at these levels

has significant public health implications because of the sizable

portion (20.5 percent) of children who have blood lead levels

between 20 and 30 pddl.

The percent of children 6 months-5 years with blood lead

levels greater than 25 and 20 ~gJdl is shown in table B. If the

cutoff used for screening children for lead toxiciw were lowered

from 30 to 25 pgjdl, approximately 1 out of 4 (24.5 percent) black children and approximately 1 out of 20 (5.5 percent) white children would be considered as having elevated

blood lead levels. If it were lowered to 20 pgJdl, about one out of

two (52.2 percent) black children and one out of five (18.1

percent) white children would be considered as having elevated

blood lead levels.

Blood lead levels of children in association

with other selected factors

Mean blood lead levels for those in early childhocd differed

by the educational attainment of the head of the household

(figure 6 and table 8). Regression analysis indicates that there

was a significant inverse relationship between mean blood lead

level and the education of the head of the household for black

and white children 6 months--5 years. This relationship was

not present for children 6– 17 years.

The reported association of hand-t~mouth activity to blood

lead level in early childhood44-46 was supported by the

NHANES II data. Accounting for race using regression analysis, mean blood lead values were significantly higher (approximately 3 ~g/dl more) for chi~den 6 months-5 years who were

reported as eating unusual substances than for those of the

same age for whom no such behavior was reported (table 9).

The average blood lead value for these children was much less

than that observed among children with overt lead toxicity

secondary to eating paint chips high in lead.

The percent of young children with a history of pica was

significantly higher for those 6 months–3 years old (11.0 percent) than for those 4-5 years old (3.2 percent) and for children

living in households with annual family incomes less than

$10,000 (11.9 percent) than for those in households with

incomes equal to or greater than $10,000 (6.0 percent)

(table 10). Also, the percent of children with pica reported is

significantly higher for children with blood lead levels equal to

or greater than 20 @dl than for those with values less than

20 @all.

Among children 6 months–5 years, 4.1 percent were reported as having been tested for lead poisoning (table 11). Black

children (12.5 percent) were more likely to have been tested

than white children (2.7 percent). Approximately 1 out of

4 black children (24.6 percent) living in large urban areas

(1 million or more population) reported being tested. The mean

blood lead level was significantly higher for those tested than

for those not tested for lead poisoning (table 9). This latter

finding could be expected during the late 1970’s because lead

screening programs primarily targeted children at high risk of

exposure to lead, for example, those living in old, dilapidated

households in the inner cities.38

The results of tests for lead poisoning are not presented as

national estimates because of small sample size. However, a

30

25

20

15

10

5

0

r

N Less than high school education

EziHigh school education

wala

0.5-5 years 6–1 7 years 0.5-5 years 6-17 years

Black White

Figure 6. Blood lead levels of children and youths 6 months-17 years by education of the head of household. race, and age United States,

1976-80

11
summary of the results of these tests in relation to blood lead

level for examinees 6 months--5 years is presented in

table VIII of appendix I.

The effects of alcohol consumption,

smoking, and occupation on blood lead

levels of men and women

Recent studies show that alcohol consumption, cigarette

smoking, and occupational exposure to lead can influence the

blood lead levels of adults.25-27 However, there has been concern that the effects attributed to one such factor may be confounded by one of the other factors, making the results of some

studies difllcult to interpret.

An analysis of the NHANES II data indicated that smoking

and certain occupations were associated with higher mean blood

lead levels among U.S. workers.47 Regression analysis suggests

that [the effects of drinking alcohol, smoking, and occupational

exposure to lead can contribute independently and additively

to blood lead level (figure 7 and tables 12 and 13).

IFor persons ages 18--74 years, accounting for differences

associated with age and race by regression, the mean blood

lead level was significantly greater for men and women who

smoke cigarettes than for nonsmokers. The average blood lead

level also increased significantly with the number of cigarettes

smoked. Mean blood lead level was significantly higher for

exarninees who reported drinking alcohol (beer, wine, and liquor)

than for nondrinkers. There was also a positive association

between mean blood lead level and number of alcoholic drinks

consumed for men and women (table 12).

For U.S. workers 18--74 years, regression analysis indicated that blood lead levels were significantly associated with

22

21

20

19

18

77

16

15

14

13

12

11

10

9

t 0

—

T

TT

High

exposurel

Men

1Degree of potential exposure at the workplace

IN Drinker, smoker

❑

....,.

:~:~:~ Drinker, nonsmoker

❑ Nondrinker, smoker

D

Nondrinker, nonsmoker

I 95-percent confidence intervals

T

Low

exr30surel

High Low

wposurel exposurel

Women

—

Figure 7. Blood lead levels of persons 18–74 years by sex, degree of potential occupational axposure to lead, alcohol consumption, and

smoking status: United States, 1976–80

12
sex, race, alcohol consumption, smoking, and the degree of

potential exposure to lead at the workplace. For the latter, occupational categories were defined using data previously collected

during the National Occupational Hazard Survey48 conducted

by the National Institute for Occupational Safety and Health

from 1972– 1974. (For details on definitions of occupational

categories, see appendix III.) Accounting for differences associated with race, age, alcohol consumption, and smoking, the

mean blood lead level was significantly higher for the highpotential exposure (to lead at the workplace) group than for the

low-potential exposure group for men and for women (table

13). In the regression analysis, there was a significant interaction between occupation and race for men, but no significant

interactions between the independent variables for women. Based

on the NHANES II data, the analysis indicated that the effects

of alcohol consumption, smoking, and exposure to lead at the

workplace were additive.

Chronological trend in blood lead levels

Analysis of a chronological trend in the NHANES II data

indicates that average blood lead levels in the United States

dropped approximately 37 percent from February 1976 through

February 1980 (figure 8).49,50 This trend cannot be attributed

After accounting for differences in race, sex, age, region of the

country, season, income, and degree of urbanization, the predicted mean blcml lead level horn the regression model decreased

over the survey period from 14.6 to 9.2 ~g/dl of whole blood ( a

drop of 5.4).4 Similar analyses were conducted for subgroups

defined by race, sex, and age and showed statistically significant reduction in average blood lead levels over the 4-year

period ranging from 31 to 42 percent (figure 9).

Changes in general exposure to lead from environmental

sources were also investigated in relation to the downward trend

in blood lead levels.4 Only three major factors could have accounted for the downward trend an increased public awareness of lead sources and lead toxicity, a decreasing amount of

lead in the diet, and a reduction in the use of lead in gasoline.

There was no evidence that exposure to lead in paint or in the

diet, or that factors associated with general public awareness

could explain the drop ~ blood lead levels. However, the correlation of blood lead levels with national estimates of the amount

of lead used in gasoline production was highly significant

(p< 0.001) overall and in population subgroups defined by

race, sex, and age (table C). Although strong correlation does

not prove cause and effect, the most likely explanation for the

decline in blood lead levels is a reduction of lead usage in

gasoline during the 4-vear period.4 Details of the statistical

to errors in laboratory measurement or the survey sample design. kalysis are pr&ented ;n appendix IV.

20

15

10

5

0 [ 1 I I I I I I I I I 1

0 5 10 15 20 25 30 35 40 45 50 55

Timel

11 unit =28 days.

—. -. -----

Figure 8. Chronological trend in averaga blood lead Ievela for persons 6 months-74 years: United States, 1975-80

13
50

r

Tota I Black White Male Female 0.5-5 6-17 18-74

Race Sexl Age in yearsl

1For white persons only.

Figure 9. Reduction in mean blood lead levels for persons 6 montlw-74 years by race, sex, and ege: United States, 1976-80

Tabla C. Pearaon correlation coefficients between the average blood lead levels for 6-month periods and the total lead used in gaaoline

production per 6 months and the averages of the coefficients, by selected charac:teriatics: Unitad States, 1976-80

Coefficient for 6-month periodsl 2

Jenuary-June April-September

and and

Characteristic July-Decembe@ October-March4 Average

All races . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.920 0.938 0.929

Blacks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.678 0.717 0.698

Whites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.929 0.955 0,9142

Sax

Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.944 0.960 ().9,52

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.912 0.943 0.9128

Age

0.5-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.955 0.969 0.962

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.908 0.970 C).glsg

18-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.920 0.924 tj.glzz

lThe lead values used to compute the averages were preadjusted by regression analysis to account for the effects of income; degree of urbanization; region of the

—

count~ season; and, when appropriate, race, sex, and age.

‘All correlation coefficients ware statistically significant (P< 0.001 ) except those for blacks (P< 0.05).

3Averagea were based on 6-month periods, except for the first and last, which covered only February 1976 through Juna 1976 and January 1980 through February

1980, respectively.

4Averages wera based on 6-month periods, axcept for the last, which covered only October 1979 through Februav 1980.

‘Blacks could not be analyzed according to sex and age subgroups because of inadequate sample sizes.

NOTE: < = lass than.

An independent study of the chronological trend in the blood lead in the U.S. population during the NHANE!3 II

NHANES II blood lead data conducted by Janney et al.51 survey period” and concluded that there was “a strong

reported similar findings. These studies 4’51 and their ccm- correlation between gasoline lead usage and blood lead

elusions have been reviewed for the U.S. Environmental levels. In the absence of scientifically plausible alternative

Protection Agency by an expert panel of statisticians.52 explanations, the hypothesis that gasoline lead is an important

The panel reported the existence of “strong evidence that causal factor for blood lead levels must receive serious conthere was a substantial decline in the average level of sideration. ”

14
The association of erythrocyte

protopo~phyrin with blood lead level and

iron status

During the last decade, the measurement of erythrocyte

protoporphyrin (EP) has been increasingly used in screening

young children for lead toxicity and for iron deficiency,38 and

in identifying adults with occupationally related exposure to

lead.53Erythrocyte protoporphyrin combines with iron to form

heme, a constituent of hemoglobin. It is elevated in iron deficiency anemia and lead toxicity. The accumulation of EP can

result from the adverse metabolic effects of lead on heme synthesis and from iron deficiency.s4 Individuals who have both

iron deficiency and elevated blood lead levels could be particularly susceptible to the biological effects of lead.55

Analysis of the NHANES II data suggested that both low

iron status (percent transferringsaturation less than 16.0 or total

iron-binding capacity greater than or equal to 450 pg/dl serum)

and elevated blood lead levels (> 30 pg/dl) were associated

with increased EP levels in the U.S. population 6 months-74

years. The percent of persons with elevated EP levels (that is,

above the 95th percentile, which was 30 pg EP/dl of whole

blood in the NHANES II data) was highest among those with

low iron status and elevated blood lead levels (figure 10). The

cumulative percent distribution of EP by each of six blood

lead-iron status categories is shown in figure 11. Comparisons

among these groups indicated that the entire distribution of EP

was influenced by the effect of blood lead and iron status. The

median EP was more than 10 pg/dl higher for the high-bloodlead and low-iron-status group (32.7 pg EP/dl of whole blood)

than for any of the other five groups. For the lead screening

programs, the interrelated effects of iron status and blood lead

level on EP level are an important consideration in evaluating

the current criteria for identifying children or adults with excess body burdens of lead using EP tests and blood lead analyses.55The relationship of EP and blood lead levels of children

6 months–5 years of age was examined to provide information

that may be helpfid in evaluating the criteria involved in using

EP levelsin lead screening programs. As shown in table D, about

20 percent of the examined children with blood lead values of

30 ~gjdl or more had EP levels of 50 p~dl or more.

60 r 56.2

Low Medium High

Blood lead statusz

1Low, percent TS = 16.0 or TIBC >450 Pg/dl; normel, percent

TS >16.0 and TIBC <450 pg/dL

2Low, PbB <20 ~g/dl; medium, 20< PbB <30 pg/dl; high, PbB >

30 /.Lg/dL

NOTE Percent computed using weighted data.

EP = erythrocyre protoporphyrin level.

PbB = blood lead level.

TIBC = total iron-binding capacny.

TS = tranaferrin saturation.

Pg/dl = micrograms per deciliter.

2 = equal to or greater than.

> = greater than.

< = equal to or less than.

< = less than.

Figure 10. Percent of parsons 6 months-74 years with erythrocyte

protoporphyrin values of 30 #g/all or more by blood lead and

iron status: United States, 1976-80

15
—

300

200

100

40

20

10

6

/

1

300

200

100

40

20

10

6

)

I

/

/

/,

100

40

20

10

6

i

t

o 20 40 60 80 100 0 20 40 60 80 100

PbB >30 ~gldl 20< PbB <30 p(jdl

Cumulative percent distribution of EP levels

1-

‘o 20 40 60 80 100

PbB <20 ~g/dl

Cumulative percent distribution of EP Ievelal

Iron statua

- _ percent TS <16.0 or TIBC >450 ~g/dl

_ percent TS >16.0 and TIBC <450 pg/dl

NOTE Percent computed using weighted dats.

EP = erythocyte protoporphyrin level.

PbB = blood lead level.

TIBC = total iron-binding capacity.

TS = tranaferrin aaturaticrn.

pgldl = micrograms per deciliter.

> = equal to or greater than.

> = greater than.

< = equal to or less than.

< = less than.

Figure 11. Cumulative percent distribution of erythrocyte protoporphyrin levels for persons 6 months-74 years by blood Iced levels and iron

stetus: United States, 1976-80

16
Table D. Number of examined children 6 months-5 years, estimated population, percent of estimated population, and standard error of the

percent by selectad erythrocyte protoporphyrin levels. according to selected blood lead levels: United States, 1976-80

Blood lead level in micrograms per deciliter whole blood

25 or more 30 or more

Erythrocyte protoporphyrin Estimated Percent of Standard Estimated

level in micrograms per Number of

Percent of Standard

population estimated error or Number of

deciliter whole blood axaminees~

population estimated error of

in thousands population the percent examineesl in thousands population the percent

Total . . . . . . . . . . . . . . . . . . 256 1,534 100.0 . . . 117 675 100.0

Less than 35 . . . . . . . . . . . .

. . .

189 1,137 74.1 2.7 69 389

35-49 . . . . . . . . . . . . . . . . . 37 216

57.7 6.0

14.1 2.2 25 152

500r more . . . . . . . . . . . . . 30 181

22.5 3.8

11.8 2.0 23 134 19.8 4.6

‘The total number of blood samples thst were obtained by venipuncture that had both valid blood lead and erythrocyte protoporphyrin valuea was2,365 (estimated

population in thousands= 16,862). See sppendix I for details on the elimination of blood samples from the deta.
Summary

National estimates of blood lead levels indicated that exposure to lead in our environment was ubiquitous throughout

the U.S. population. For children, blood lead levels were contingent upon age, sex, race, socioeconomic status, and degree

of urbanization of place of residence. For children 6 months-5

years, the average blood lead level and the prevalence of elevated

blood lead levels (30 pg/dl or more) were substantially higher

for black children than for white children during the survey

period. An inverse relationship between family income (or

education of the head of the household) and average blood lead

levels in children ages 6 months-5 years suggests that soci~

economic factors are associated with community and household sources of lead that can influence childhood exposure to

lead. There is greater concern about childhood exposure to

these sources because of the greater susceptibility of young

children to the toxic effects of lead.5’8’’6’5GIn addition, young

children are more likely to be exposed to lead in dust, dirt, and

lead-based paint because of increased hand-to-mouth activity

and the tendency to eat unusual substances.

For adults ages 18-74 years, blood lead levels were

associated with age, race, sex, occupation, alcohol consump

tion, and smoking. There was a striking sex difference in average blood lead levels, with signitlcantly higher values for men

than for women. Analyses of the NHANES II data indicated

that the effects of exposure to lead associated with occupation,

alco:hol consumption, and smoking are additive.

A 37-percent drop in average blood lead levels of persons

6 months-74 years over the survey period indicated a

lessening of exposure to lead in the U.S. population. The most

reasonable explanation for the decline in average blood lead

levels is the decrease in the use of lead in gasoline over the

same period.

Both iron status and blood lead level are associated t~ith

erytlhrocyte protoporphyrin (EP) level. Measurement of EP

has been used by many of the lead screening programs to screen

individuals initially for high lead levels and for iron deticiehcy.

National estimates from the NHANES II data indicate that

the interrelationship of iron status and blood lead level and

their combined effects on EP should be considered wheli the

criteria for identifying children or adults with excess body burdens of lead are evaluated.

18
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74A. Azar, K. Habibi, and R D. Snee: An epidemiologic approach to

community air Pb exposure using personal air samplers. Environ.

Qual. Saj2ty, Supplement II Lead, pp. 254-270,1975.

75Environmental Protection Agency: Quantitative evaluation of lead

and biochemical indices of lead exposure in physiologicrd media. Air

Quality Criteria Document for Lead, Ch. 9. Environmental Criteria

and Assessment OffIce. Research Triangle Park, N.C. In preparation.

76U.S. Bureau of the Census: 1970 Census of Population. Alphabetical Index of Industn.es and Occupations. Washington. U.S. GovernmentPrinting Oftlce, 1971.

77National Institute for Occupational Safety and Health: National

Occupational Hazard Survey, 1972, 1973, 1974, and Vol. 1-3.

DHHS 74-127,77-123,78-114. Rockville, Md.

78J. Neter and W. Wassermarr Applied Linear Statistical Models:

Regression, Analysis of Van.ante, and Expen.mental Designs, pp.

313-315, Homewood, 111.Richard D. Irwin, 1974.

79SAS Institute StafE SAS User’s Guide Statistics, pp. 101-110.

Cary, N.C. SAS Institute Inc., 1982.

80Environmental Protection Agency: EPA Quarterly Lead Additive

Reports. Field Operations and Support Section Division, Oflice of

Air, Noise and Radiation Enforcement. Washington, D.C., 1980.

21
List of detailed tables

1.

2.

3.

4.

5.

6.

7.

Blood lead levels of persons 6 months-74 years, with

arithmetic mean, standard error of the mean, and selected

percentiles, by race and age: United States, 1976 -80.....

Blood lead levels of males 6 months-74 years, with

arithmetic mean, standard error of the mean, and selected

percentiles, by race and age: United States, 1976 -80.....

Blood lead levels of females 6 months-74 years, with

arithmetic mean, standard error of the mean, and selected

percentiles, by race and age: United States, 1976 -80.....

Blood lead levels of persons 6 months-74 years, with

arithmetic mean, standard error of the mean, geometric

mean and geometric standard deviation, and percent distribution by race, age, and sex: United States, 1976 -80.....

Blood lead levels of persons 6 months–74 years, with

arithmetic mean, standard error of the mean, geometric

mean and geometric standard deviation, and percent distribution, by income, race, age, and sex: United States,

1976 -80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead levels of persons 6 months-74 years, with

arithmetic mean, standard error of the mean, geometric

mean and geometric standard deviation, and percent distribution, by urban or rural residence, race, age, and sex:

United States, 1976 -80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead levels of persons 6 months-74 years, with

23

24

25

26

27

29

8.

9.

10.

11.

12.

13.

mean and geometric standard deviation, and percent distribution, by central city or non-central city residence, race,

age, andsex: United States, 1976–80 . . . . . . . . . . . . . . . . . . 31

Blood lead levels of persons 6 months-17 years, with

arithmetic mean, standard error of the mean, and percent

distribution, by education of the head of the household,

race and age: United States, 1976 -80 . . . . . . . . . . . . . . . . . . 32

Blood lead levels of children 6 months–5 years, with

arithmetic mean, standard error of the mean, and percent

above selected levels, by selected medical history items and

race of child: United States, 1976–80. . . . . . . . . . . . . . . . . . 33

Percent of children 6 months-5 years with a history of

eating unusual substances by selected characteristics: ~

United States, 1976-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Percent of children 6 months-5 years with a history of

being tested for lead poisoning by selected characteristics:

United States, 1976-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Blood lead levels of persons 18-74 years, with arithmetic

mean and standard error of the mean, by sex, degree of

cigarette smokhg, and degree of alcohol consumption:

United States, 1976 -80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Blood lead levels of U.S. workers 18-74 years, with

arithmetic mean and standard error of the mean, by selected

characteristics: United States, 1976 -80 . . . . . . . . . . . . . . . . 37

arithmetic mean, standard error of the mean, geometric

22
Table 1. Blood lead levels of persona 6 months-74 years, with arithmetic mean, standard error of the mean, and selected percentiles, by rata

and age: United States, 1976-80

Estimated Standard Percentile

population Number Arithmetic error of

Race and age in thousends~ examined2 mean the mean 5th Ioth 25th 50th 75th 90th 95th

All races3

Total . . . . . . . . . . . . . . . . . . . . . . .

6months-2 years . . . . . . . . . . . .

3-5 years . . . . . . . . . . . . . . . . . . .

6-8 years . . . . . . . . . . . . . . . . . . .

9-n years . . . . . . . . . . . . . . . . . .

12-14 years . . . . . . . . . . . . . . . . .

15-17 years . . . . . . . . . . . . . . . . .

18-24 yaars . . . . . . . . . . . . . . . . .

25-34 years . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . . . .

45-54 years, . . . . . . . . . . . . . . . .

55-64 years, . . . . . . . . . . . . . . . .

65-74 years . . . . . . . . . . . . . . . . .

White

Total . . . . . . . . . . . . . . . . . . . . . . .

6months-2 years . . . . . . . . . . . .

3-5 yeara . . . . . . . . . . . . . . . . . . .

6-8 years . . . . . . . . . . . . . . . . . . .

9-n years . . . . . . . . . . . . . . . . . .

12-14 years . . . . . . . . . . . . . . . . .

15-17 yesre . . . . . . . . . . ...<...

18-24 years . . . . . . . . . . . . . . . . .

25–34 years . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . . . .

45-54 years . . . . . . . . . . . . . . . . .

55-64 years . . . . . . . . . . . . . . . . .

65-74 years . . . . . . . . . . . . . . . . .

Black

Total . . . . . . . . . . . . . . . . . . . . . . .

6months-2 years . . . . . . . . . . . .

3-5 years . . . . . . . . . . . . . . . . . . .

6-8 years . . . . . . . . . . . . . . . . . . .

9-n years . . . . . . . . . . . . . . . . . .

12-14 years . . . . . . . . . . . . . . . . .

15-17 years . . . . . . . . . . . . . . . . .

18-24 years . . . . . . . . . . . . . . . . .

25-34 years . . . . . . . . . . . . . . . . .

35-44 yeare . . . . . . . . . . . . . . . . .

45–54 years . . . . . . . . . . . . . . . . .

55-64 years . . . . . . . . . . . . . . . . .

65-74 years . . . . . . . . . . . . . . . . .

203,554

7,676

9,186

10,259

10,621

11,632

12,452

27,448

32,752

23,651

23,032

20,350

14,496

174,528

6,166

7,455

8,436

8,960

9,705

10,429

23,522

28,227

20,348

20,137

18,300

12,824

23,853

1,164

1,421

1,526

1,567

1,697

1,738

3,406

3,499

2,527

2,259

1,760

1,288

9,933

759

1,613

451

377

448

444

985

1,041

753

724

1,149

1,189

8,369

589

1,287

374

315

367

368

849

885

648

625

1,020

1,042

1,332

141

278

65

57

75

66

119

125

87

82

116

121

Blood lead level in micrograms Dar deciliter

13.9

16.3

15.9

13.9

12.9

11.4

12.1

13.1

13.7

14.6

15.3

14.6

14.4

13.7

15.0

14.9

13.3

12.4

11.0

12.0

13.0

13.5

14.4

15.1

14.4

14.2

15.7

20.9

20.8

17.7

15.8

13.7

13.0

13.8

15.1

15.6

17.2

17.2

15.9

0.24

0.57

0.40

0.47

0.39

0.32

0.35

0.33

0.33

0.36

0.32

0.32

0.23

0.24

0.56

0.41

0.46

0.39

0.29

0.36

0.34

0.32

0.41

0.33

0.34

0.28

0.48

0.96

0.55

1.10

0.75

0.71

0.69

0.67

0.81

0.84

0.90

1.01

0.71

7.0

8.0

8.0

7.0

7.0

6.0

6.0

6.0

6.0

7.0

7.0

7.0

7.0

6.0

7.0

8.0

7.0

7.0

6.0

6.0

6.0

6.0

6.0

7.0

7.0

7.0

8.0

11.0

10.0

*

*

*

*

7.0

7.0

*

*

8.0

8.0

8.0 10.0 13.0 17.0 21.0 25.0

9.0 11.0 15.0 20.0 25.0 29.0

9.0 11.0 15.0 19,0 24.0 27.0

8.0 11.0 13.0 16.0 20.0 24.0

8.0 10.0 12.0 16.0 19.0 20.0

7.0 8.0 11.0 14.0 16.0 19.0

7.0 9.0 11.0 14.0 18.0 22.0

8.0 9.0 12.0 16.0 21.0 23.0

7.0 10.0 13.0 17.0 21.0 24.0

8.0 10.0 13.0 18.0 22.0 27.0

8.0 11.0 14.0 18.0 23.0 26.0

8.0 10.0 14.0 18.0 22.0 26.0

8.0 10.0 13.0 17.0 21.0 25,0

8.0 10.0 13.0 16.0 21.0 24.0

8.0 11.0 14.0 18.0 23.0 26.0

9.0 11.0 14.0 18.0 22.0 25.0

8.0 10.0 12.0 16.0 20.0 22.0

8.0 9.0 12.0 15.0 18.0 20.0

7.0 8.0 11.0 13.0 16.0 17.0

7.0 9.0 11,0 14.0 18.0 22.0

8.0 9.0 12.0 15.0 21.0 23.0

7.0 9.0 72.0 16.0 27.0 24.0

7.0 10.0 13.0 17.0 22.0 27.0

8.0 11.0 14.0 18.0 23.0 26.0

8.0 10.0 13.0 17.0 22.0 26.0

8.0 70.0 13.0 77.0 21.0 24.0

9.0 11.0 15.0 19.0 23.0 27.0

11,0 15.0 19.0 25.0 33.1 38.0

12.0 16.0 20.0 24.0 30.0 35.0

11.0 13.0 17.0 21.0 27.0 *

11.0 13.0 16.0 18.0 20.0 *

8.0 10.0 74.0 16.0 20.0 *

8.0 10.0 12.0 15.0 20.0 *

8.0 10.0 13.0 17.0 21.0 23.0

8.0 10.0 14.0 19.0 24.0 28.0

9.0 11.0 14,0 19.0 21.0 *

Ifl.o 13.0 16.0 21.0 25.0 *

10.0 12.0 16.0 20.0 25.0 28.0

9.0 11.0 14.0 19.0 22.0 26.0

lAt the midpoint of the survay, March 1, 1978.

‘With lead determinations from blood specimens drawn by venipuncture.

31ncludes data for races not shown separately.

23
Table 2. Blood lead levels of males 6 months-74 years, with arithmetic maan, standard error of the mean, and selected parcantiles, by race

and age: United States, 1976-80

Estimated Standard Percentile

population Number Arithmetic error of

Race and age in thousandsl examined2 mean the mean 5th 10th 25th 50th 75th 90th 95th

All races3

Total . . . . . . . . . . . . . . . . . . . . . . .

6months-2 years . . . . . . . . . . . .

3-5 years . . . . . . . . . . . . . . . . . . .

6-8 years . . . . . . . . . . . . . . . . . . .

9-n yeara . . . . . . . . . . . . . . . . . .

12-14 years . . . . . . . . . . . . . . . . .

15-17 years . . . . . . . . . . . . . . . . .

18-24 years . . . . . . . . . . . . . . . . .

25-34 years . . . . . . . . . . . . . . . . .

35-44 yaars . . . . . . . . . . . . . . . . .

45-54 yeara . . . . . . . . . . . . . . . . .

55-64 years . . . . . . . . . . . . . . . . .

65-i’4 years . . . . . . . . . . . . . . . . .

White

Total . . . . . . . . . . . . . . . . . . . . . . .

6months-2 years . . . . . . . . . . . .

3-5yaars . . . . . . . . . . . . . . . . . . .

6-8 years . . . . . . . . . . . . . . . . . . .

9-n years . . . . . . . . . . . . . . . . . .

12-14 yaars . . . . . . . . . . . . . . . . .

15-17 years . . . . . . . . . . . . . . . . .

18-24 years . . . . . . . . . . . . . . . . .

25-34 yaara . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . . . .

45–54yaars . . . . . . . . . . . . . . . . .

55-64 yeara . . . . . . . . . . . . . . . . .

65-74 yeare . . . . . . . . . . . . . . . . .

Black

Total . . . . . . . . . . . . . . . . . . . . . . .

6months-2 years . . . . . . . . . . . .

3-5 yeare . . . . . . . . . . . . . . . . . . .

6-8 years . . . . . . . . . . . . . . . . . . .

9-n years . . . . . . . . . . . . . . . . . .

12-14 years . . . . . . . . . . . . . . . . .

15-17 yeare . . . . . . . . . . . . . . . . .

18–24 years . . . . . . . . . . . . . . . . .

25-34 years . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . . . .

45-54 year3 . . . . . . . . . . . . . . . . .

55-64 years . . . . . . . . . . . . . . . . .

65-74 yaars . . . . . . . . . . . . . . . . .

99,062

3,926

4,695

5,345

5,301

5,920

6,320

13,275

15,895

11,367

11,114

9,607

6,297

85,112

3,120

3,789

4,357

4,472

4,932

5,298

11,522

13,884

9,740

9,878

8,580

5,537

11,171

589

718

804

750

851

867

1,533

1,546

1,112

1,044

801

555

4,945

396

851

229

200

228

245

492

502

342

347

565

548

4,153

293

676

199

164

190

200

435

423

295

306

500

472

664

85

146

23

32

34

40

49

65

37

35

57

61

Blood lead level in micrograms oer deciliter

0.26

0.64

0.44

0.55

0.39

0.39

0.42

0.42

0.45

0.46

0.49

0.40

0.29

0.27

0.63

0.44

0.55

0.43

0.37

0.47

0.45

0.46

0.50

0.54

0.44

0.36

0.52

1.12

0.78

*1 .59

0.92

1.07

0.85

0.91

0.85

1.56

1.27

1.69

1.30

-,

16.1 8.0 9.0 12.0 15.0 19.0 24.0 27.0

16.8

16.0

14.4

13.6

12.6

13.9

15.9

16.8

17.7

17.5

16.7

16.3

15.8

15.6

15.0

13.7

13.0

12.2

13.7

15.8

16.6

17.6

17.2

16.4

16.0

18.3

20.2

21.0

*1 9.3

16.3

14.9

14.8

16.8

19.1

19.1

20.9

21.2

18.7

8.0 9.0 12.0 15.0 20.0 26.0 31.0

8.0 9.0 12.0 15.0 79.0 24.0 28.0

7.0 9.0 11.0 13.0 17.0 22.0 27.0

8.0 9.0 10.0 13.0 16.0 19.0 22.0

7.0 8.0 10.0 13.0 15.0 17.0 20.0

7.0 8.0 10.0 13.0 16.0 21.0 22.0

8.0 9.0 12.0 15.0 19.0 23.0 2!6.0

9.0 10.0 13.0 16.0 20.0 24.0 27.0

9.0 11.0 13.0 17.0 21.0 26.0 32.1

9.0 11.0 13.0 17.0 21.0 26.0 28.0

8.0 10.0 12.0 15.0 20.0 25.0 29.0

9.0 10.0 12.0 15.0 20.0 23.0 28.0

8.0 9.0 12.0 15.0 19.0 23.0 27.0

8.0 9.0 11.0 15.0 19.0 24.0 27.0

8.0 9.0 11.0 14.0 18.0 22.0 25.0

7.0 8.0 10.0 13.0 16.0 20.0 24.0

8.0 9.0 10.0 13.0 15.0 18.0 ~1.o

7.0 8.0 9.0 12.0 14.0 17.0 19.0

7.0 8.0 10.0 13.0 16.0 22.0 ti3.o

8.0 9.0 12.0 15.0 19.0 23.0 27.0

9.0 10.0 12.0 16.0 20.0 24.0 27.0

9.0 11.0 13.0 16.0 2’1.o 26.0 31.0

9.0 11.0 13.0 17.0 20.0 26.0 28.0

8.0 10.0 72.0 15.0 20.0 25.0 29.0

8.0 10.0 12.0 15.0 20.0 23.0 27.0

10.0 11.0 14.0 17.0 21.0 27.0 30.0

*

11.0 15.0 18.0 24.0 33.1 *

10.0 12.0 16.0 20.0 25.0 30.0 38,0

* *

16.0 17.0 22.0 “ *

* *

13.0 15.0 18.0 * *

* *

11.0 15.0 18.0 * *

* *

12.0 14.0 18.0 * :

* *

13.0 17.0 20.0 * ~

*

12.0 15.0 18.0 22.0 28.0 *

* *

12.0 17.0 21.0 * *

* *

17.0 21.0 24.0 * *

*

12.0 16.0 19.0 25.0 28.0 *

*

10.0 12.0 17.0 21.0 27.0 “

lAt tha midpoint of the suwey, March 1, 1978.

‘With lead determination from blood specimens drawn by venipuncture.

31ncludea data for races not shown ssparstely.

24
Table 3. Blood lead levels of females 6 months-74 years, with arithmetic mean, standard error of the mean, and selactad percentiles, by race

and age: United Stetas, 1976-80

Estimated Standard Percentifa

population Number Arithmetic error of

Race and age in thousendsl examined2 mean the mean 5th 10th 25th 50th 75th 90th 95th

All races3

Total . . . . . . . . . . . . . . . . . . . . . . .

6months-2 yeara . . . . . . . . . . . .

3-5 years . . . . . . . . . . . . . . . . . . .

6-8 years . . . . . . . . . . . . . . . . . . .

9–ll years . . . . . . . . . . . . . . . . . .

12-14 years . . . . . . . . . . . . . . . . .

15-17 years . . . . . . . . . . . . . . . . .

18-24 years . . . . . . . . . . . . . . . . .

25-34 years . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . ..e

45-54 years . . . . . . . . . . . . . . . . .

55-64 yeare . . . . . . . . . . . . . . . . .

65–74 yeare . . . . . . . . . . . . . . . . .

White

Total . . . . . . . . . . . . . . . . . . . . . . .

6months-2 yeara . . . . . . . . . . . .

3-5years . . . . . . . . . . . . . . . . . . .

6-8years . . . . . . . . . . . . . . . . . . .

9-n years . . . . . . . . . . . . . . . . . .

12-14 years . . . . . . . . . . . . . . . . .

15-17 years . . . . . . . . . . . . . . . . .

18-24 years . . . . . . . . . . . . . . . . .

25-34 years . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . . . .

45-54 years . . . . . . . . . . . . . . . . .

55-64 years . . . . . . . . . . . . . . . . .

65-74 years . . . . . . . . . . . . . . . . .

81ack

Total . . . . . . . . . . . . . . . . . . . . . . .

6months-2 years . . . . . . . . . . . .

3-5 years . . . . . . . . . . . . . . . . . . .

6-8 yeara . . . . . . . . . . . . . . . . . . .

9-n years . . . . . . . . . . . . . . . . . .

12-14 years . . . . . . . . . . . . . . . . .

15-17 years . . . . . . . . . . . . . . . . .

18–24 years . . . . . . . . . . . . . . . . .

25–34 years . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . . . .

45-54 yeere . . . . . . . . . . . . . . . . .

55-64 yeare . . . . . . . . . . . . . . . . .

65-74 years . . . . . . . . . . . . . . . . .

104,492

3,750

4,491

4,914

5,320

5,712

6,131

14,173

16,856

12,284

11,918

10,743

8,198

89,417

3,066

3,666

4,079

4,488

4,773

5,130

11,999

14,343

10,607

10,259

9,720

7,287

12,682

575

703

722

817

846

871

1,873

1,953

1,415

1,215

959

733

Blood lead level in micrograms per deciliter

4,988

363

762

222

177

220

199

493

539

411

377

584

641

4,218

296

611

175

151

177

168

414

462

353

319

520

570

668

56

132

42

25

41

26

70

60

50

47

59

60

11.9

15.7

15.8

13.5

12.3

10.1

10.3

10.5

10.8

11.7

13.3

12.8

12.8

11.7

14.5

14.8

13.0

11.7

9.8

10.2

10.4

10.7

11.5

13.2

12.7

12.8

13.4

21.7

20.6

16.3

15.4

12.4

10.8

11.4

12.0

13.0

13.6

14.0

13.6

0.23

0.59

0.42

0.56

0.48

0.38

0.31

0.27

0.24

0.34

0.30

0.38

0.29

0.23

0.58

0.44

0.59

0.43

0.38

0.31

0.29

0.25

0.38

0.33

0.40

0.31

0.45

1.07

0.76

1.15

0.88

1.13

0.72

0.46

0.69

0.35

0.59

0.79

0.59

6.0

7.0

8.0

7.0

7.0

5.0

5.0

5.0

5.0

6.0

7.0

6.0

7.0

6.0

7.0

8.0

7.0

6.0

5.0

5.0

5.0

5.0

6.0

7.0

6.0

7.0

7.0

*

11.0

*

*

*

*

*

*

*

*

*

*

7.0 9.0

9.0 11.0

9.0 11.0

8.0 10.0

7.0 9.0

6.0 8.0

6.0 8.0

7.0 8.0

6.0 8.0

7.0 9.0

7.0 10.0

7.0 9.0

8.0 9.0

7.0 9.0

8.0 10.0

9.0 11.0

8.0 10.0

7.0 8.0

6.0 7.0

6.0 8.0

6.0 8.0

6.0 8.0

7.0 8.0

7.0 10.0

7.0 9.0

8.0 9.0

8.0 10.0

13.0 15.0

13.0 16.0

*

12.0

*

12.0

*

9.0

*

9.0

7.0 9.0

7.0 8.0

8.0 10.0

*

11.0

9.0 10.0

9.0 10.0

11.0

14.0

15.0

12.0

12.0

10.0

10.0

10.0

10.0

11.0

13.0

12.0

12.0

11.0

14.0

14.0

12.0

11.0

9.0

10.0

10.0

10.0

11.0

13.0

12.0

12.0

13.0

21.0

20.0

15.0

16.0

12.0

10.0

11.0

11.0

13.0

13.0

14.0

13.0

14.0 18.0 20.0

19.0 24.0 29.0

19.0 24.0 26.0

16.0 20.0 22.0

15.0 19.0 19.0

12.0 15.0 16.0

12.0 15.0 16.0

12.0 15.0 16.0

13.0 16.0 19.0

14.0 17.0 19.0

16.0 19.0 22.0

15.0 19.0 22.0

15.0 19.0 22.0

14.0 17.0 20.0

18.0 22.0 24.0

18.0 22.0 25.0

15.0 18.0 21.0

14.0 18.0 19.0

12.0 14.0 16.0

12.0 15.0 16.0

12.0 15.0 16.0

13.0 16.0 18.0

14.0 17.0 19.0

15.0 20.0 23.0

15.0 19.0 22.0

15.0 19.0 22.0

16.0 20.0 22.0

25.0 34.0 “

24.0 29.0 32.0

19.0 * *

18.0 * *

14.0 ‘ *

12.0 * *

14.0 16.0 *

14.0 18.0 *

16.0 19.0 *

16.0 * *

17.0 20.0 *

16,0 19.0 *

‘At tha midpoint of ths swvey, March 1, 1978.

2With lead determination from blood spacimens drswn by venipuncture.

31ncludas data for races not shownseparately.

25
Table 4. Blood lead levels of persons 6 months–74 years, with arithmetic mean, standard error of the mean, geometric mean, and geometric

standard deviation, and percent distribution by race, age, and sex: United States, 1976-80

Blood lead level in micrograms per deciliter

Equal

Estimated Standard to m

population error Geometric Less

in Number

greater

Arithmetic of the Geometric standard than than

Characteristic thousands examiner+ mean mean mean devietion 10 10-19 20-29 30-39 40

—

All races3

Alleges . . . . . . . . . . . .

6 months-5 years

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

White

Alleges . . . . . . . . . . . .

6 months-5 years

6-17 years . . . . . . . . .

18-74 yeara:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

Black

Alleges . . . . . . . . . . . .

6 months-5 years . . .

6-17 years . . . . . . . . .

1B-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

203,554

16,862

44,964

67,555

74,173

174,52B

13,641

37,530

59,142

64,215

23,853

2,584

6,529

6,592

8,148

9,933 13.9 0..4 12.8 1.50

2,372 16.0 0.42 14.9 1.47

1,720 12.5 0.30 11.7 1.45

2,796 16.8 0.28 15.8 1.45

3,045 11.8 0.22 11 .() 1.46

8,369 13.7 0.24

1,876 14.9 0.42

1,424 12.1 0.30

2.6 1.50

4.0 1.44

1.3 1.44

2,431 16.6 0.29 15.6 1.44

2,638 11.7 0.23 10.9 1,47

1,332 15.7 0.48 14.6 1.49

419 20.9 0.61 19.6 1.44

263 14.8 0.53 14.0 1.42

304 19.1 0.70 lB. I 1.44

346 12.7 0.44 12.() 1.40

22.1

12.2

27.6

7.6

33.7

23.3

14.5

30.4

8.1

34.6

13.3

2.5

12.8

2.3

24.7

62.9

63.3

64.8

64.1

60.6

62.B

67.4

63.4

64.8

59.9

63.7

45.3

70.9

56.4

68.1

1.6

3.5

0.5

3.4

0,3

1,5

1.8

0.4

3.3

0.4

2.3

10.2

0.7

4.5

0.4

0.!5

0.7

0.:2

0.:2

0.:2

Q.!j

0.”7

2.0

I ,!CJ

Percent distribution

13.0

20.5

7.1

24.2

5.2

12.2

16,1

5.8

23.3

5.0

20.0

40.0

15.6

34.9

7.2

‘At the midpoint of the survey, March 1, 1978.

‘With lead determination from blood specimens drawn by venipuncture.

31nc!udea data for racea not ahown separately.

26
Table 5. Blood lead levels of persons 6 months-74 years, with arithmetic mean, standard error of the mean, geometric mean and geomatric

standard deviation, and percent distribution, by income, race, age, and sex: United States, 1976-80

Blood lead Ieval in micrograms per deciliter

Equal

Estimated Stendard to or

population error Geometric Less

in Number Arithmetic

greater

of the Geometric standard than than

Characteristic thousandsl examined2 mean mean mean deviation 10 10-19 20-29 3>39 40

UNDER $6,000

All races3

6 months-5 years . . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

White

Alleges . . . . . . . . . . . .

6 months-5 years . . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

Black

Alleges . . . . . . . . . . . .

6 months-5 yeara . . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

$6,000-$14,999

All races3

Alleges . . . . . . . . . . . .

6 months-5 years . . .

6-17 years . . . . . . . . .

1B-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

White

Alleges . . . . . . . . . . . .

6 months-5 years . . .

6–17 years . . . . . . . . .

18-74 yeara:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

Black

Alleges . . . . . . . . . . . .

6months-5 years . . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

$15,000 OR MORE

All races3

Alleges . . . . . . . . . . . .

6 months-5 years . . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

See footnotes at end of table.

29,410

2,465

5,046

7,945

13,954

21,542

1,408

3,067

6,340

10,727

7,355

917

1,927

1,451

3,061

80,416

7,534

17,533

25,436

29,913

68,135

6,252

13,936

22,162

25,784

10.334

1,037

3,159

2,762

3,376

87,062

6,428

20,814

31,674

28,146

1,862

448

230

454

730

1,315

256

140

353

566

512

176

87

93

156

4,033

1,083

672

1,094

1,184

3,473

887

531

956

1,039

533

163

125

121

124

3,718

774

761

1,152

1,031

14.5

20.0

14.6

17.5

12.1

14.0

18.1

14.0

17.0

11.8

15.8

22.9

15.7

19.5

12.9

14.2

16.2

12.9

17.4

11.8

13.9

15.3

12.4

17.1

11.7

16.1

20.7

14.9

20.4

12.9

13.5

14.1

11.7

16.3

11.6

0.40

0.56

0.61

0.70

0.36

0.44

0.61

0.69

0.76

0.42

0.47

0.89

0.76

0.76

0.39

0.25

0.46

0.41

0.32

0.20

0.26

0.48

0.39

0.33

0.21

0.48

0.64

0.71

0.82

0.61

0.24

0.41

0.25

0.29

0.28

13.1

18.6

13.5

16.0

11.2

12.6

17.0

12.9

15.4

10.9

14.6

21.4

14.8

18.4

12.2

13.1

15.1

12.0

16.3

11.0

12.8

14.3

11.6

16.1

10.9

14.9

19.6

14.1

18.9

12.3

12.6

13.3

11.1

15.3

10.9

1.56

1.47

1.48

1.55

1.49

1.56

1.44

1.51

1.55

1.51

1.53

1.47

1.42

1.51

1.44

1.51

1.46

1.46

1.44

1.45

1.51

1.44

1.47

1.43

1.46

1.47

1.41

1.37

1.46

1.39

1.48

1.43

1.41

1.42

1.45

Percent distribution

Zz.1

3.9

16.1

10.9

32.5

25.1

5.4

20.1

12.5

35.6

13.5

2.1

9.1

5.2

21.9

20.5

10.6

22.5

6.5

32.9

21.9

12.3

25.8

7.0

34.2

11.7

1.9

9.8

1.1

23.5

23.6

17.6

34.0

7.7

35.0

5Y.Y

50.6

68.5

54.7

61.0

59.1

61.5

67.3

56.9

57.8

63.3

36.9

70.4

46.2

72.0

62.9

63.0

68.B

60.7

61.5

62.5

66.6

66.9

61.3

60.7

64.2

47.0

75.9

53.3

66.1

63.9

69.0

61.2

68.6

59.8

15.1

34.6

12.6

29.1

5.9

13.1

27.2

9.5

25.1

5.8

20.3

42.5

18.2

44.6

6.1

14.4

22.2

8.5

27.7

5.0

13.5

18.9

7.1

27.0

4.3

20.7

39.0

14,3

36.1

10.4

11.2

12.2

4.6

20.8

5.0

1.9

9.3

2.7

3.2

0.1

1.6

5.3

3.0

3.1

0.1

2.4

15.2

2.3

2.5

1.9

3.7

0.2

4.3

0.5

1.8

2.1

0.2

4.2

0.5

2.3

10.1

5.8

1.2

1.1

0.2

2.7

0.2

1.0

1.6

0.1

2.1

0.5

1.1

0.6

0.1

2.4

0.7

0.5

3.3

1.5

0.3

0.5

0.8

0.1

0.3

0.1

0.5

0.3

1.1

2.0

3.7

0.1

0.1

0.2

27
Table 5. Blood lead levels of persons 6 months-74 years, with arithmetic meen, standard error of the mean, geometric mean and geomatric

standard deviation, and percent distribution, by income, race, age, and sex: Unitecl States, 1976-80—Con.

Blood lead level in micrograms per deciliter

Equal

Estimated Standard to or

population error Geometric Less

in Number Arithmetic

greater

of the Geometric standard than than

Characteristic thousands~ axamined2 mean mean mearl deviation 10 10-19 20-29 30-39 40

$15,000

OR MORE—Con.

White

Alleges . . . . . . . . . . . .

6 months-5 yeara . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

Black

Alleges . . . . . . . . . . . .

6 months–5 years . . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

79,707 3,401 13.4 0.26 12.5 1.48

5,707 690

19,174 705

28,808 1,052

26,018 954

4,995 224

502 60

1,225 42

3.7 0.44 12.9

1.6 0.28 11.0

6.1 0.31 15.2

1.7 0.29 10.9

.41

.40

.42

.45

4.9 0.58 13.9 1.45

7.2 0.83 16.2 1.41

3.6 0.79 12.6 1.51

1,949 73 17.5 0.81 16.7 1.36

1,318 49 11.5 0.63 11.0 1.33

Percent distribution

24.1 63.9 10.8 1.1 0.1

19.4 70.1 9.8 0.6 0.1

34.9 60.9 4.0 0.2 .

8.3 88.6 20.4 2.5 0.2!’

34.6 60.1 5.1 0.2 .’

15.5 63.7 19.1 1.7 -

5.1 58.2 33.7 2.7 0.1

25.6 57.0 17.4

0.4 67.2 29.0 3.4 -

33.0 64.8 2.2

‘At the midpoint of the survey, March 1, 1978.

2With lead determinations from blood specimens drawn by venipuncture.

31ncludes data for races not shown separately.

28
Table 6. Blood lead levels of persons 6 months-74 years, with arithmetic mean, standard error of the mean, geometric rT Ian and gaometric

standard deviation, and parcent distribution, by urban or rural residence, race, age, and sex United Statas, 1976-80

Blood fead level in micrograms per deciliter

Equal

Estimated Standard to or

population error Geometric Less greater

in Number Arithmetic of the Geometric standard than than

Characteristic thousands~ examined2 mean mean mean deviation 10 10-19 20-29 30-39 40

URBAN, 1 MILLION

PERSONS OR MORE

All racas3

Alleges . . . . . . . . . . . .

6 months-5 yaars . . .

6–17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

White

Alleges . . . . . . . . . . . .

6 months-5 yaars . . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

Black

Alleges . . . . . . . . . . . .

6 months-5 years . . .

6-17 years . . . . . . . . .

1B–74 years

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

URBAN, FEWER

THAN 1 MILLION

PERSONS

All races3

Alleges . . . . . . . . . . . .

6 months-5 years . . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

White

Alleges . . . . . . . . . . . .

6 months-5 years . . .

6–17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

Black

Alleges, . . . . . . . . . . .

6 months-5 years . . .

6-17 years......,..

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

59,532

4,344

12,893

19,541

22,755

46,407

3,112

9,681

15,809

17,805

11,687

1,093

3,010

3,267

4,318

79,906

6,891

16,988

25,672

30,356

67,707

5,297

13,871

22,369

26,171

9,783

1,246

2,717

2,551

3,268

2,395

544

414

677

760

1,767

358

294

531

584

570

172

111

132

155

3,869

944

638

1,050

1,237

3,144

699

510

889

1,046

612

205

113

134

160

15.0

18.0

13.8

17.8

12.9

15.0

16.6

13.3

17.8

13.1

15.5

22.2

15.3

18.4

12.4

13.9

16.5

12.6

16.B

11.8

13.6

15.4

12.2

16.5

11.6

15.9

20.3

14.5

19.6

13.0

0.37

0.53

0.53

0.34

0.40

0.31

0.59

0.55

0.28

0.36

0.84

0.83

0.83

1.22

0.78

.

0.32

0.67

0.35

0.37

0.32

0.32

0.67

0.36

0.38

0.32

0.54

0.78

0.64

0.71

0.62

14.0

16.8

13.1

16.9

12.2

14.0

15.6

12.6

16.9

12.4

14.4

20.8

14.6

17.4

11.8

12.8

15.4

11.7

15.7

11.0

12.5

14.4

11.4

1!5.4

10.8

14.8

19.2

13.6

18.6

12.4

1.45

1.46

1.38

1.41

1.41

1.44

1.43

1.38

1.40

1.40

1.46

1.43

1.36

1.41

1.40

1.51

1.46

1.47

1.45

1.45

1.50

1.44

1.46

1.45

1.46

1.49

1.39

1.46

1.44

1.39

Percent distribution

14.3

7.1

15.8

3.3

23.8

13.6

8.4

17.B

3.1

21.5

14.6

2.9

9.4

3.0

28.5

22.4

10.3

27.6

8.3

33.2

24.2

12.9

30.4

9.1

35.2

11.3

2.2

15.0

1.4

18.3

66.3

56.7

72.9

62.8

67.1

67.1

63.3

72.2

63.0

68.5

63.8

38.0

74.4

59.4

64.5

62.9

61.7

64.5

63.0

62.2

62.4

66.5

63.1

63.7

60.5

64.6

46.4

69.1

53.1

74.3

17,3

29.0

10.9

29.8

8.6

17.3

24.3

9.7

29.7

9.4

19.0

43.9

15.7

32.5

7.0

12.8

24.5

7.4

24.6

4.2

11.6

19.0

6.1

23.2

3.8

21.4

41.2

15.3

39.7

7.4

1.6

6.2

0.4

3.2

0.4

1.5

3.9

0.3

3.0

0.5

2.1

12.0

0.5

4.3

1.6

3.1

0.5

3.6

0.3

1.5

1.3

0.4

3.5

0.3

2.2

9.6

0.6

4.3

0.5

1.0

0.9

0.1

0.5

0.1

0.2

0.?

0.5

3.2

0.8

0.3

0.4

0.5

0.1

0.3

0.3

0.5

0.2

0.5

0.6

1.5

See footrmtea at end of table.

29
Table 6. Blood lead levels of persons 6 months-74 yeara, with arithmetic meatn, standard error of the mean, geometric mean and geometric

standard daviation, and percent distribution, by urban or rural residence, race, age, and sex: United States, 1976-80—Con.

Blc}od lead level in micrograms per deciliter

Equal

Estimated Standard to or

population error Geometric Less greater

in Number Arithmetic of the Geometric standard than

Characteristic

than

thousands~ examined2 mean mean mean deviation 10 10-19 20-29 30-39 40

RURAL

All races3

Alleges . . . . . . . . . . . .

6months-5 years .,.

6-17 yeara . . . . . . . . .

18-74 years:

Men, . . . . . . . . . . . .

Women . . . . . . . . . .

White

All agea . . . . . . . . . . . .

6months-5 years . . .

6-17 years . . . . . . . . .

18-74 yeara:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

Black

Ad ages . . . . . . . . . . . .

6months-5 years . .

6-17 years . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . .

Women . . . . . . . . . .

64,116

5,627

15,083

22,343

21,063

60,414

5,233

13,978

20,963

20,239

2,383

245

802

774

562

3,669 13,0 0.40 11.9 1.53

884 13.9 0.64 13.0 1.44

668 11.4 0.52 10.7 1.45

1,069 16.1 0.43 15.1 1.46

1,048 10.7 0,36 9.8 1.49

3,458 12.B 0.39 11.8 1.52

819 13.5 0.57

620 11.2 0.48

1,011 15.9 0.44

1,008 10,6 0.36

2.7 1.42

0.5 1.44

4.8 1.44

9.8 1.49

150 16.2 0.68 14.4 1.61

42 18.3 2.60 16.5 1.65

39 13.9 1.33 13.0 1.49

38 20.4 1.47 18.3 1.56

31 12.4 0.97 11.3 1.59

Percent distribution

28.9

1B.2

37.2

10,4

44.7

29.6

19.7

38.8

10.6

44.8

15.5

2.1

18.6

2.9

33.6

59.8

70.3

58.6

66.5

51.8

59.9

70.8

57.8

67.3

51.9

60.0

68.0

64.0

55.3

59.2

9.5

9.4

3.7

19.1

3.0

8.9

8,3

2.9

18.6

2.7

18.7

19.6

15.7

29.3

7.3

1,6

1.9

0.5

3.5

0.3

1.5

1.2

0.5

3.2

0.3

3.2

6.2

1.8

5.9

0.2

0.2

0.5

p.2

0.1

0.3

0.3

2.6

4.1

6.6

,.

lAt the midpoint of the survey, March 1, 1978,

2Withlead determinationa from blood specimens drawn byvenipuncture,

31ncludes data for racas not shown separately.

30
Table 7. Blood lead Ievela of persons 6 months-74 years, with arithmetic mean, standard error of the mean, geometric mean and geometric

standard deviation, and percent distribution, bycentral city or non-central city residence, race, age, and sex: Unitad States, 1976-80

Blood lead level in micrograms per deciliter

Estimatad Standard

population error Geometric Less Equal to

in Number Arithmetic of the Geometric standard than

Characteristic thousands~

or greater

examine~ mean mean mean deviation 20 20-29 than 30

CENTRAL CITY

All races3

Alleges . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . . . . . . . . . .

Women . . . . . . . . . . . . . . . . . .

White

Alleges . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . .

6–17 years . . . . . . . . . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . . . . . . . . . .

Women . . . . . . . . . . . . . . . . . .

Black

Alleges . . . . . . . . . . . . . . . . . . . .

6months-5 yeare . . . . . . . . . . .

6-17 yaars . . . . . . . . . . . . . . . . .

18-74 yaar~

Men . . . . . . . . . . . . . . . . . . . . .

Women . . . . . . . . . . . . . . . . . .

NON-CENTRAL CITY

All races3

All ages . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . . . . . . . . . .

Women . . . . . . . . . . . . . . . . . .

White

Alleges . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . .

18-74 years

Men . . . . . . . . . . . . . . . . . . . . .

Women . . . . . . . . . . . . . . . . . .

Blsck

Aliases . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . .

18-74 years:

Men . . . . . . . . . . . . . . . . . . . . .

Women . . . . . . . . . . . . . . . . . .

Percent distribution

24,560

1,822

5,124

7,661

9,953

14,602

885

2,710

4,778

6,229

8,856

855

2,259

2,514

3,228

13.9

18.5

13.9

1.46

1.50

1.37

1.41

1.42

1.43

1.45

1.37

1.40

1.41

1.48

1.46

1.37

1.41

1,43

81.5

51.8

85.0

71.2

91.4

82.7

64.8

85.2

73.2

90.8

78.2

36.7

83.6

65.7

91.3

16.6

36.6

15.0

25.2

8.4

16.1

30.7

14.8

24.3

8.9

18.8

44.7

16.4

28.2

8.7

1.9

11.6

3.6

0.2

1.2

4.5

2.5

0.3

3.0

18.6

6.1

1,123

286

177

14.9

20.0

14.6

0.67

0.71

0.87

297

363

17.3

12.6

0.70

0.70

16.3

11.8

625

133

86

14.8

17.4

14.3

0.56

0.84

0.93

13,9

16.3

13.6

183

223

17.1

13.0

0.56

0.66

16.1

12.3

452

143

84

15.4

23.1

15.0

0.94

1.30

1.00

14.2

21.6

14.3

103

122

18.0

12.2

1.42

0.98

17.0

11.5

34,908

2,519

7,746

11,880

12,763

31,741

2,223

6,949

11,032

11,538

2,831

238

751

753

1,090

1,268

257

236

380

395

5.1 0.30 14.1

6.5 0.60 15.6

3.3 0.59 12.6

1.44

1.41

1.39

80.0

73.0

90.9

17,8

23.3

8.5

2.2

3.7

0.6

8.2 0.31 17.2

3.2 0.32 12.5

1.40

1.39

62.7

90.4

32.8

8.9

4.5

0.7

1.45

1.42

1.38

79.9

74.7

91.6

17.9

21.5

7.9

2.2

3.8

0.5

1,138

224

207

15.1

16.2

13.0

0.32

0.65

0.63

14.1

15.3

12.3

348

359

18.1

13.2

0.30

0.35

17.2

12.5

1.40

1.41

63.1

89.6

32.1

9.6

4.8

0.8

118

29

27

16.0

19.2

16.0

0.60

0.74

0.67

15.2

18.5

15.4

1.39

1.33

1.34

79.2

55.1

84.1

19.8

41.6

14.1

1,0

3.3

1.8

29

33

19.7

13.1

1.39

0.58

18.7

12.7

1.42

1.29

50.6

98.1

48.1

1.9

1.3

‘At the midpoint of the swvey, March 1, 1978.

2With lead determinations from blood specimens drawn by venipuncture.

Slncludes data for races not shown separately.

31
Tabla 8. Blood lead levels of persons 6 months-17 years, with arithmetic maan, standard error of the mean, and percent distribution, by

education of the head of household, race, and age: United State% 1976-80

Blood lead level in micrograms per deciliter

—

Standard

error Less Equal to

Number Arithmetic of the than or greater

Education of head of household, race, and age examined! mean maan 20 20-29 than 30

LESS THAN HIGH SCHOOL

All racesz

6months-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . .

6months–5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

White

6months-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Black

6months-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

HIGH SCHOOL

All racesz

6months-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

White

6months-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Black

6months-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-17 yeara . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

COLLEGE LEVEL OR ABOVE

All raceaz

6months-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6months-5yeacs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6–17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

White

6months-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6months–5yesra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Black

6months-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

666

345

321

506

262

244

135

69

66

2,199

1,273

926

.

1,715

966

749

440

274

166

1,192

734

4.58

1,054

636

418

98

69

29

‘14.0

‘19.1

‘13.1

13.3

17.9

12.5

15.8

,22.2

14.8

13.3

16.4

12.6

12.7

15.1

12.2

16.2

21.4

14.8

12.5

14.4

12.0

12.3

13.9

11.8

15.8

18.0

14.8

0.62

0.88

0.61

0.57

0.80

0.57

1.04

1.86

1.12

0.33

0.49

0.31

0.35

0.63

0.34

0.38

0.63

0.43

0.28

0.40

0.31

0.30

0.43

0.32

1.01

0.96

1.12

Percent distribution

83.3

58.2

87.6

87.6

65.3

91.3

70.5

37.2

75.9

89.3

73.4

93.0

91.5

80.6

93.8

79.2

47.4

88.3

92.0

84.7

94.0

93.6

88.4

94.9

72.4

58.6

78.3

14.3

32.0

11.3

10.2

28.4

7.2

27,1

45.8

24.1

9.5

22.5

6.5

7.9

17.4

5.8

17.0

39.5

10.6

7,7

14.0

6.0

6.3

10.9

5.1

26.3

37.1

21.7

2.4

9.8

1.1

2.2

6.3

i.5

2,4

17.0

1.2

4.1

0.5

0.6

2.0

0.4

3.8

13.1

1.1

0.3

1.3

0.1

0.7

1.3

4.3

lWith Ieaddeterminationa from blood specimens drawn byvenipuncture.

‘Includes data for races not ahown separately.

32
Table 9. Blood Iced levels of children 6 months-5 years, with arithmetic mean, standard error of the mean, and percent above selected levels,

byselected medical history itamsand race of child: United States, 1976-80

Blood lead level in micrograms par decilitar

20 or more 25 or more 30 or more

Standard

error Standard Standard Standard

Selected medical history Number Arithmetic of the error of error of arror of

items and race of child examined~ mean mean Parcent the percent Parcent the percent Percent the percent

PRIOR TEST FOR LEAD

POISONING (REPORTED)

All racesz

Yes . . . . . . . . . . . . . . . . . . . . . .

No. . . . . . . . . . . . . . . . . . . . . . .

White

Yes . . . . . . . . . . . . . . . . . . . . . .

No . . . . . . . . . . . . . . . . . . . . . . .

Black

Yes . . . . . . . . . . . . . . . . . . . . . .

No. . . . . . . . . . . . . . . . . . . . . . .

EATING UNUSUAL

SUBSTANCES (REPORTED)

All racesz

Yes . . . . . . . . . . . . . . . . . . . . . .

No. . . . . . . . . . . . . . . . . . . . . . .

White

Yes. . . . . . . . . . . . . . . . . . . . . .

No. . . . . . . . . . . . . . . . . . . . . . .

Black

Yes . . . . . . . . . . . . . . . . . . . . . .

No . . . . . . . . . . . . . . . . . . . . . . .

122 21.2 0.70

2,226 15.B 0.43

5B 17.2 0.47

1,800 14.8 0.44

61 25.3 1.28

352 20.3 0.62

1B2 19.2 1.02

2,192 15.8 0.38

123 17.5 1.11

1,753 14.7 0.39

53 23.7 1.61

366 20.5 0.59

4B.4 3.15 26.1 3.81

23.2 2.32 8.3 0.99

2B.8 4.42 8.9 3.48

17.5 2.35 5.4 0.82

68.5 5.62 42.4 6.19

50.0 4.07 22.2 3.12

47.5 6.72 19.3 4.06

22.6 2.01 8.2 0.85

37.5 7.42 14.9 4.23

16.7 2.06 4.8 0.67

70.4 7.5B 33.6 7.85

49.8 3.89 23.3 2.63

14.3 2.53

3.5 0.47

2.2 1,35

2.0 0.34

26.0 4.26

10.3 1.48

8.7 2.23

3.6 0.50

5.6 1.84

1.7 0.34

19.3 7.14

11.3 1.64

lWith lead determinations from blood specimens drawn by venipuncture.

‘Includes dsta for races not shown separately.

33
Table 10. Percent of children 6 months-5 years with a history of eating unusuel substances by selected characteristics: United States,

1976-80

All racesl White Black

Number

Characteristic examined2

Standard Standard Standard

error error error

of the Number of the Number of the

Percent percent examinedz Percent percent examined2 Percent percant

Age

6months–5 years . . . . . . . . . . . . . .

6months-3 years . . . . . . . . . . . . . .

4-5 years . . . . . . . . . . . . . . . . . . . .

Sex

Boys . . . . . . . . . . . . . . . . . . . . . . . . .

Girls . . . . . . . . . . . . . . . . . . . . . . . . .

Annual family income

Less than $10,000 . . . . . . . . . . . . .

$10,000 ormore . . . . . . . . . . . . . . .

Degree of urbanization

Urban, 1 million pereons or more . . .

Urban with less than 1 million

persons and rural . . . . . . . . . . . . . .

Prior teat for lead poisoning

{reported)

Yes . . . . . . . . . . . . . . . . . . . . . . . . . .

No . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead level in

micrograms per deciliter

4,117

2,556

1,561

2,142

1,975

1,699

2,296

948

3,169

199

3,879

117

503

1,752

8.1

11.0

3.2

7.6

8.7

11.9

6.0

8.3

8.1

10.0

8.0

16.4

14.1

5.2

0.44

0.58

0.42

0.64

0.48

1.06

0.48

0.75

0.57

3,263

2,022

1,241

1,662

1,601

1,149

2,041

618

2,645

2,36 95

0.43 3,143

4.36 42

2.22 306

0.64 1,528

7.5

10.3

2.8

7.1

8.0

11.4

5.8

7.8

7.4

9.0

7.4

18.7

13.2

5.1

0.55 723

0.73 443

0.42 280

0.74 399

0.63 324

1.27 484

0.61 196

1.38 298

0.58 425

3.01 101

0.53 608

6.77 67

2.38 173

0.74 179

11.4

15.1

5.2

10.5

12.4

13.1

9.5

8.7

13.4

11.3

11.3

18.2

14.8

7.7

300rmora . . . . . . . . . . . . . . . . . . .

20-29 . . . . . . . . . . . . . . . . . . . . . . .

Less then 20 . . . . . . . . . . . . . . . . . .

1Includes data for races not shown separately.

‘Number examined in the lead subsample; except for blood lead level, number with lead determinations from blood specimens drawn by venipuncture.

1.:28

1.63

1.40

1.75

2.30

1.48

1.96

1.75

1.92

3.79

1.42

6.30

3.69

1.65

34
Table 11. Percent of children 6 months-5 years with a history of being tested for lead poisoning by selected characteristics: United States,

1976-80

All races~ White Black

Standard Standard Standard

error error

Number

error

of the Number of the Number

Characteristic

of the

examined2 Percent percent examine~ Percant parcent examined2 Percent percent

Age

6months-5 yeara . . . . . . . . . . . . . .

6months-3 years . . . . . . . . . . . . . .

4-5 years . . . . . .’. . . . . . . . . . . . . . .

Sex

Boys . . . . . . . . . . . . . . . . . . . . . . . . .

Girls . . . . . . . . . . . . . . . . . . . . . . . . .

Annual family income

Less than $10,000 . . . . . . . . . . . . .

$10,000 or more . . . . . . . . . . . . . . .

Degree of urbanization

Urban, 1 million persons or mora . . .

Urban with less than 1 million

persons and rural . . . . . . . . . . . . . .

Eating unusual substances

(reported)

Yes . . . . . . . . . . . . . . . . . . . . . . . . . .

No . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead Iavel in

micrograms per deciliter

300r more . . . . . . . . . . . . . . . . . . . .

20-29 . . . . . . . . . . . . . . . . . . . . . . .

Less than 20 . . . . . . . . . . . . . . . . . .

4,078

2,535

1,5.43

4.1

3.0

6.0

0.60

0.54

0.63

3,238 2.7 0.50

2,009 1.7 0.40

1,229 4.4 0.80

709

435

274

12.5

11.0

15.2

2.17

2.40

2.40

2.63

2.39

3.00

1.88

4.78

1.56

4.15

2.31

3.48

2.07

2.35

2,124

1,954

3.5

4.7

0.71

0.60

1,651 2.3 0.61

1,587 3.1 0.51

392

317

11.0

14.1

1,686

2,271

6.7

2.6

0.98

0.62

1,142 3.5 0.64

2,024 2.3 0.67

478

188

15.9

7.3

932

3,146

8.2

2.7

1.91

0.61

608 2.8 0.97

2,630 2.7 0.62

292

417

24.6

3.8

333

3,745

5.1

4.0

1.29

0.61

237 3.2 1.16

3,001 2.6 0.50

86

623

12.6

12.5

Micrograms per deciliter

41 3.1 2.40

300 4.7 1.41

1,517 2.4 0.45

115

495

1,738

15.5

7.2

2.9

2.89

1.43

0.53

66

171

176

26,3

13.2

8.2

I Includes data for races not shown separately.

2Number examined in tha lead subsample; except for blood lead level, number with lead determinations from blood specimens drawn by venipuncture,

35
Table 12. Blood lead levels of persons 1B–74 years, with arithmetic mean and standard error of the mean, by sex, degraa of cigarette smoking,

and degree of alcohol consumption: United States, 1976-80

Men Women

Standard Standard

error error

Number Arithmetic of the Number Arithmetic of the

Smoking and drinking status examined~ mean mean examinedf mean mean

Nonsmokeraz . . . . . . . . . . . . . . . . . . . . . . . . . 1.453 15.6 0.28 2,079 11.2 0.23

Cigarette smokers2 . . . . . . . . . . . . . . . . . . . . 1,095 18.5 0.35 960 12.9 0.2)

Number of cigarettes smoked per day

Less than 15 . . . . . . . . . . . . . . . . . . . . . 267 17.4 0.48 365 12.3 0.34

15-29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 492 18.5 0.45 401 12.9 0.40

Greater than 29 . . . . . . . . . . . . . . . . . . . . 329

Drinking status

Nondrinkers . . . . . . . . . . . . . . . . . . . . . . . . . . 844

Drinkers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,937

Number of alcoholic drinks

consumed per day

Less than l . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,420 16.5 0.26 1,375 12.0 0.2!7

l or more . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517 19.2 0.42 171 14.0 0.4.3

9.2 0.48 190 13.9 0.4.0

5.8 0.50 1,491 11.2 0.28

7.2 0.26 1,546 12.2 0.25

l~th lead determinations from blood specimens drawn by VeniPUnCture.

2Nonsmokers include those not currently smoking cigarettes, a pipe, or cigars at the time of examination. Cigarette smokers include those currently smoking cigarel%es

at the time of examination whether or not they smoke cigars ors pipe.

3Nondrinkers and drinkers refer to consumption of alcoholic beverages, including baer, wine, c~rliquor.

36
Tabla 13. Blood Iaad levels of U,S. workars 18-74 years, with arithmetic maan and standard error of tha mean, by salacted characteristics:

United Statas, 1976-80

Degree of potentiel exposure to iced at the workplace

Tote/ High Low

Stendard Standard Standerd

error error

Number

error

Arithmetic of the Number Arithmetic of the

Characteristic

Numbar Arithmetic of the

examined2 mean mean examined2 mean mean examined2 mean mean

MALE WORKERS,

18-74 YEARS

Allraces3. . . . . . . . . . . . . . . .

White . . . . . . . . . . . . . . . . . . .

Black . . . . . . . . . . . . . . . . . . .

Drinking and smoking

status4

Nondrinker, nonsmoker. . . .

Nondrinker, smoker . . . . . . .

Drinker, nonsmoker . . . . . . .

Drinkar, smoker . . . . . . . . . .

FEMALE WORKERS,

18-74 YEARS

Allraces3, . . . . . . . . . . . . . . .

White. . .,, . . . . . . . . . . . . . .

Black . . . . . . . . . . . . . . . . . . .

Orinking and smoking

status4

Nondrinker, nonsmoker. . . .

Nondrinker, smoker . . . . . . .

Drinker, nonsmokar . . . . . . .

Drinker, smoker . . . . . . . . . .

1,622

1,40B

183

259

157

540

655

1,310

1,107

183

378

132

442

357

17.3

17.1

19.4

15.4

18.2

16.1

18.7

11.8

11.7

12.2

10.7

12.3

11.3

13.2

0.32

0.34

0.81

0.43

0.87

0.41

0.33

0.25

0.25

0.48

0.35

0.34

0.32

0.39

1,045

893

133

160

110

320

449

303

252

47

79

42

75

107

18.3

18.1

21.0

16.2

19.1

17.0

19.7

12.9

13.2

11.8

11.5

12.2

12.5

14.4

0.39 577 15.5 0.36

0.42 515 15.5 0.37

0.75 50 15.9 1.14

0.57

1.10

0.51

0.40

99 14.0 0.67

47 16.2 0.82

220 14.8 0.46

206 16.7 0.53

0.38 1,007 11.5 0.28

0.39 855 11.3 0.28

0.68 136 12.4 0.60

0.48 299 10.4 0.37

0.70 90 12.4 0.42

0.98 367 11.1 0.36

0.60 250 12.8 0.45

1High and low potsntial sxposurs groupa were defined using information on typss of occupations with observed potential exposure to leadfrom the National Occupational

Hazards Survey (NOHS) conducted from 1972 through 1974. Those reporting agricultural occupation and thoas reporting a selected group of professional and

aemiprofesaional occupations were excluded. The former were excluded because farm-related occupations are not covered under the prowamna of the Occupational

Safety and Health Act of 1970 and thus were not part of the NOHS. The latter were excluded becauae of the difficulty m claasdying them aa enhar high or low potential

exposure to lead.

‘With lead determinations from blood specimens drawn by venipun~ture,

Slncludas data for racea not shown separately.

4Drinkera and nondrinkers refer to consumption of alcoholic beverages, including beer, wine, or liquOr; smokers include those CUrrentlY smokmg cigarettes, a PiPer or

cigars at the time of examination; nonsmokers include axsmokers.

37
Appendixes

Contents

I.

II.

III.

IV.

Statistical notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Suwey design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . ! . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . 40

Estimation procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Nonresponse bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . 42

Description ofexclusions and ofrespondents pertainingto tests forlead poisoning . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Limitations ofthe data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Measures ofvariability . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Data reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Tests ofsignificance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . #. . . . . . . . . . . . . . . . . . . . . . . , . . 46

Statistical analysis ofthe effectsof analytic erroron national estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Model used for analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Estimationofmeans and variance components forNHANES II bloodleaddata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Computational methods ofanalysis Noe l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Computational methods ofanalysis No. 2 . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Examination ofpotential bias in estimating analytic error... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ! . . . . . . 52

Demographic and socioeconomic terms and dietary and medical history items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Statistical analysis of the chronological trend in the NHANES II blood lead levels . . . . . . . . . . . . . . . . . . , . . . . . . . . . . 56

Linear regression analysis ofthe-time trend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ’56

Regression model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Results fromthe timetrend analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Linear regression analysis ofNHANES II blood lead levels alnagasoline lead variable . . . . . . . . . . . . . . . . . . . . . . . 57

Correlation analysis between blood lead level and leadused ingasoline production . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

List ofappendix figures

I. Estimating probabilities ofelevated blood lead levels fiomobserved levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

II. Scattergram ofblood lead levels determined fromthe lowquality controlbloodpool by chronological time: National

Health andNutritionExamination Survey, 1976–80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

III. Scattergram ofblood lead levels determined fromthe highquality controlbloodpool bychronological time: National

Healtiand Nutrition Examination Suwey. 1976.80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

List of appendix tebles

I. Samplesizeandresponseratesbyage, sex, andrace:NationalHeahhandNutritionExamination Survey, 1976-80 . . . . 41

II. Number of examined persons and estimated population, by race, age, and sex of the examinee: United States,

1976-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . ! . . . 42

III. Percent distribution of the nonresponse adjustment factors: National Health and Nutrition Examination Survey,

1976-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Iv. Nonresponse amongsarnple persons 6months-74 years intheleadsubsample by age: NationalHealth andNutrition 43

Examination Survey, 1976-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

38
v.

VI.

VII.

VIII.

IX.

x.

XI.

XII.

XIII.

XIV.

xv.

XVI.

Nonresponse among examined persons 6 months-74 years in the lead subsample by age, race, sex, income, and

degree of urbanization National Health and Nutrition Examination Survey, 1976–80 . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead determinations from specimens collected by fingersticks in children 6 months-7 years, by race: National

Health and Nutrition Examination Survey, 1976.80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Characteristics of three persons with blood lead values greater than 70.0 pg/dl who received venipuncture: National

Health and Nutrition Examination Sumey, 1976–80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Summary of history of being tested and treated for lead poisoning for children 6 months-5 years, by blood lead level:

National Health and Nutrition Examination Survey, 1976–80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Estimates usedinanalyses nos. 1and2: United States, 1976-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blood lead jevels of persons 6 months-74 years, with mean and standard deviation of the meanj percent of persons

with levels of 30 pg/dl or more, and estimated percents of persons with levels above the threshold of 30 @dl after

accounting for analytic error, by selected characteristics: United States, 1979–80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Natural logarithm of blood lead levels for the blind quality control pools with mean, standard deviation of the mean,

and estimated measurement variance by chronological time periods: National Health and Nutrition Examination

Suwey. 1976.80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Results of regression analysis of z on a chronological time variable: National Health and Nutrition Examination

Suwey. 1976.80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Results of regression of the natural logarithm of the blood lead level on time and the demographic covariates:

National Health and Nutrition Examination Survey, 1976–80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Percent decrease in blood lead levels over the survey period, after accounting for the effects of the demographic

covariates, by selected group characteristics: United States, 1976–80.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Results of regression of the natural logarithm of the blood lead level on the gasoline lead variable and the demographic

covariates: United States, 1976-80. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Percent decrease in blood lead levels over the survey period that can be explained by a decline in the use of lead in

gasoline, after accounting for the effects of the demographic covariates by selected group characteristics: United

States, 1976-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

44

45

45

45

48

49

52

52

58

59

60

61

39
Appendix 1

Statistical notes

This report is based on data collected in the second National Health and Nutrition Examination Survey (NHANES

II) from February 1976 through February 1980. NHANES

II, conducted by the National Center for Health Statistics, was

a survey of the civilian noninstitutionalized U. S. population

(including Alaska and Hawaii) 6 months-74 years of age. Both

interview and examination procedures were used to collect a

broad spectrum of demographic, socioeconomic, and morbidity data and related medical and nutritional information. During

household interviews, demographic, socioeconomic, and some

of the medical history data were obtained from sample persons.

Specially designed mobile examination centers (MEC’S), transported to each sample location, provided standardized conditions and equipment for the dietary interview, medical examination, and related clinical tests and procedures.

Survey design

NHANES II utilized a stratified, multistage design that

provided for the selection of samples at each stage with known

probability. In hierarchical order, the stages of selection were

primary sampling units (PSU’s-a PSU is a county cr a small

group of contiguous counties); census enumeration districts

(ED’s); segments (a segment is a cluster of households); households; eligible persons; and, finally, sample persons.

The first-stage sampling units selected in the previous National Health Examination Survey and NHANES I surveys

were subsets of the sample PSU’S in the National Health Interview Survey (NHIS), another major data collection program of

the National Center for Health Statistics. In NHIS the United

States is divided into 1,924 PSU’S, with 376 of the PSU’S

being selected for the sample. Sixty-five of these 376 sample

PSU’S were selected as the NHANES I sample. The PSU’S

used in previous examination surveys were defined either as a

single county or as a group of contiguous counties (except in

certain parts of New England). Many of the larger PSU’S were

defined as standard metropolitan statistical areas (SMSA’S)

and often contained several counties. The PSU’S that contained

several counties and covered a large area were not ideally suited

for an examination survey. Attempting to survey large geographic areas from a centrally located examination center created a number of logistical problems. Some examinees had

been asked to travel more than 50 miles to be examined, while

others had been asked to travel through very congested areas.

Many respondents were reluctant to travel under such conditions. The cost of followup visits to the households was also a

function of the distance or time from the examination center.

An analysis of the response rates for several stands in NHANES

I lent further support to these assumptions. The use of smlaller

areas as PSU’S would reduce both the average distance traveled. to the examination center by examinees and the cost c)fthe

fielclwork. These considerations were the basis for redefining

and restratifying the PSU’S in NHANES II.

In NHIS, 156 of the 376 PSUS are self-representing

SMSA’S. It was these 156 self-representing SMSA’S in the

NHIS design that were redefined and restratified for the

NHANES 11 design.

For NHANES II, the self-representing PSU’S in NHIS

were first split along county boundaries. Within each region,

each of the counties was classified as being either a selfrepresenting or a non-self-representing PSU. The PSU’S that

were non-self-representing were further combined into homogeneous classes or strata equal in size to the NHIS strata containing non-self-representing PSU’s.

The effect of dividing the 156 self-representing PSLJ’S in

NH.IS and redefining the PSU’S by using county boundaries

resulted in a total of 397 PSU’S: 198 of which were defined as

self-representing and 199 of which were defined as non-selfrepresenting and subsequently were used to form an additional

43 non-self-representing strata, which were combined with the

otier 220 non-self-representing PSU’S in NHIS. The average

population of a self-representing PSU was reduced from 838,000

to 584,000. In area, the average size of these PSU’S was reduced more than 60 percent, from 2,185 square miles to 855

square miles.

These 461 first-stage units (NHIS strata) were fiu-ther

stratified into a total of 64 superstrata, and one PSU was selected from each of the superstrata using a modif3ed GootbnanKish controlled selection technique.57 These 64 PSU’S represented the geographic locations visited by the MEC’S during

the survey period.

The U.S. Bureau of the Census had the major responsibility for selecting households and sample persons within each of

the PSU’S. Three sampling frames of housing units were used

to select the sample within each of the PSU’S. The list frame

consisted of all housing units based on the 1970 Census of the

Population. An area frame was used in areas with “rapid”

growth (housing units built prior to 1970) and in areas with

“ sl(Dw” growth (all housing units regardless of year built). A

new construction frame was used to supplement the list frame

NOTE: A list of referencesfollowsthe text.

40
for all places built since 1970 and in about half of the places in

the area sample that were experiencing rapid growth.

The second stage of the design consisted of the selection of

clusters of households (segments) within ED’s. An ED is a

geographical area that contains approximately 300 housing

units. To oversimple persons with low incomes, the ED’s were

stratified into a poverty stratum and a nonpoverty stratum. The

poverty strata contained ED’s with 13 percent or more of persons below the poverty level, and the nonpoverty strata contained ED’s with less than 13 percent of persons below the

poverty level as determined by the 1970 Census. ED’s withii

each stratum were selected proportionally to their measures of

size. To insure sampling reliabili~, clusters of 16 listed addresses were drawn from the sampling frames and then systematically subsampled at a rate of 1 out of 2 to produce a final

segment of 8 household address listings.

At the third stage of sampling, a list of all eligible sample

persons was made within each selected segment. Using the

following sampling rates, the sample of persons to be examined

was selected so that the younger and older age groups were

oversarnpled and so that approximately one person per sample

household was selected

Age Rate

6months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . %

6-59 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3/4

60-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . %

Of the 27,801 persons included in the NHANES II sample,

20,322 (73. 1 percent) were interviewed and examined. The

NHANES II sample size and response data by age, sex, and

race are shown in table I. Table II shows the number of examined persons and population estimates at the midpoint of the

survey by race according to sex and age.

A more complete description of the survey design is included in Vital and Health Statistics, Series 1, No. 15.’4

Estimation procedures

Because the design of NHANES II is a complex, multistage

probability sample, national estimates are derived through a

multistage estimation procedure. The procedure has three basic

components: (1) inflation by the reciprocal of the probability of

selection, (2) adjustment for nonresponse, and (3) poststratification by age, sex, and race. A brief description of each component follows:

● Inflation by the rec+rocal of the probability of selection.

The probability of selection is the product of the probabilities of selection tlom each stage of selection in the design—

PSU, segment, household, and sample person.

● Adjustment for nonresponse. The estimates are inflated by

a multiplication factor that brings estimates based on examined persons up to a levelthat would have been achieved

ifall sample persons had been examined. The nonresponse

adjustment factor was calculated by dividing the sum of

the reciprocals of the probability of selection for all selected sample persons within each of five income groups

(under $6,000, $6,000-$9,999, $10,000-$14,999,

$15,000-$24,999, and $25,000 and over), three age groups

(6 months-5 years, 6-59 years, and 60-74 years), four

NOTE: A list of referencesfollowstie text.

Tabla 1. Sample size and response rates by age, sex, and race: National Health and Nutrition Examination Survey, 1976-80

Interview and examination status

Total /nterviewedl Examined

sample

Age, sex, and race size Number Percent Number Percent

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27,601 25,286 90.95 20,322 73.10

Age

6 months-1 1 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444 431 97.1

l-5 yeara . . . . . . . . . . . . . . . . . . . . . . .

356 80.2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,625 4,445

6-n years . . . . . . . . . .

96.1 3,762 81.3

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,085 1,963 94.2

12–17 years . . . . . . . . . . . . . .

1,725 82.7

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,438 2,304 94.5

18–24 yeara . . .

1,975 81.0

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,713 2,537 93.5

25-34 years . . . . . . . . . . . . . . . . . . . . . .

2,054 75.7

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,031 2,773 91.5

35-44 yeare . . . . . . . . . . . . . . . . . . . .

2,237 73.8

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,236 2,005 89.7

45-54 years

1,589 71.1

. . . . ..-. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,149 1,866 86.8

55-64 years . . . . . . . . . . . . . . . . . . . . .

1,453 67.6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,868 3,330 86.1

65-74 years

2,556 66.1

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,212 3,632 86.2 2,615 62.1

Sex

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14,395 13,122 91.2

Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10,339 71.8

13,406 12,164 80.7 9,983 74.5

Race

White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23,537 21,350

Black. . . . . . .

90.7 17,105 72.7

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,653

Other . . . . . . . . . . . . . . . .

3,389 92.8 2,763 75.6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611 547 89.5 454 74.3

lComplstedmedicalhiato~ interview.

41
Table Il. Number of examined persons snd estimated population, by race, age, and sex of the axaminee: Unitad States, 1976-80

All rsces~ White Black

Population Population Population

Examined in Examined in Examined in

Age and sex persons thousands2 persons thousands2 persons thousands2

Both sexes

6months-74 years . . . . . . . . . . . . . . . . . . . . .

6-n months . . . . . . . . . . . . . . . . . . . . . . . . .

l-5 yeara . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-n years . . . . . . . . . . . . . . . . . . . . . . . . . . .

12-17 years . . . . . . . . . . . . . . . . . . . . . . . . . .

18-24 years . . . . . . . . . . . . . . . . . . . . . . . . . .

25-34 years . . . . . . . . . . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . . . . . . . . . . . . .

45-54 years . . . . . . . . . . . . . . . . . . . . . . . . . .

55-64 years . . . . . . . . . . . . . . . . . . . . . . . . . .

65-74 years . . . . . . . . . . . . . . . . . . . . . . . . . .

Male

6months-74 years . . . . . . . . . . . . . . . . . . . . .

6-n months . . . . . . . . . . . . . . . . . . . . . . . . . .

l-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-n years . . . . . . . . . . . . . . . . . . . . . . . . . . .

12-17 years . . . . . . . . . . . . . . . . . . . . . . . . . .

18-24 years . . . . . . . . . . . . . . . . . . . . . . . . . .

25-34 years . . . . . . . . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . . . . . . . . . . . .

45-54 yeara . . . . . . . . . . . . . . . . . . . . . . . . . .

55-64 years . . . . . . . . . . . . . . . . . . . . . . . . .

65-74 years . . . . . . . . . . . . . . . . . . . . . . . . . .

Female

6months-74 years . . . . . . . . . . . . . . . . . . . . .

6–ll months . . . . . . . . . . . . . . . . . . . . . . . . . .

l-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6–ll years . . . . . . . . . . . . . . . . . . . . . . . . . . .

12-17 years . . . . . . . . . . . . . . . . . . . . . . . . . .

18-24 years . . . . . . . . . . . . . . . . . . . . . . . . . .

25-34 yeara . . . . . . . . . . . . . . . . . . . . . . . . . .

35-44 years . . . . . . . . . . . . . . . . . . . . . . . . . .

45-54 yesrs . . . . . . . . . . . . . . . . . . . . . . . . . .

55-64 years . . . . . . . . . . . . . . . . . . . . . . . . . .

65-74 years . . . . . . . . . . . . . . . . . . . . . . . . . .

20,322

356

3,762

1,725

1,975

2,054

2,237

1,589

1,453

2,556

2,615

9,983

179

1,964

885

1,039

988

1,067

745

690

1,227

1,199

10,339

117

1,798

840

936

1,066

1,170

844

763

1,329

1,416

203,554

1,699

15,263

20,880

24,084

27,448

32,752

23,651

23,032

20,350

14,496

99,062

819

7,802

10,646

12,241

13,275

15,B95

11,367

11,114

9,607

6,297

104,492

780

7,461

10,234

11,843

14,173

16,856

12,284

11,918

10,743

8,198

17,105

285

1,979

1,397

1,610

1,738

1,901

1,379

1,264

2,262

2,290

8,389

130

1,533

725

853

846

901

653

617

1,086

1,046

8,716

155

1,446

672

757

892

1,000

726

647

1,176

1,245

174,426

1,300

12,342

17,264

20,027

23,362

28,357

20,392

20,235

18,243

12,906

85,009

646

6,263

8,768

10,133

11,442

13,864

9,808

9,865

8,642

5,576

89,418

654

6,078

8,496

9,893

11,919

14,494

10,584

10,369

9,601

7,329

2,763

62

661

288

321

268

284

173

162

264

280

1,341

42

357

136

157

121

139

70

62

129

128

1,422

20

304

152

164

147

145

103

100

135

152

23,853

238

2,346

3,094

3,435

3,406

3,499

2,527

2.259

1,760

1.288

11,171

121

1,186

1,554

1,718

1,533

1,546

1,112

1,044

pol

655

12,662

117

1,160

1,540

1,717

1,873

1,953

1,,415

1,215

:959

’733

1Includes data for races not shown separately.

2At the midpoint of the suwey, March 1, 1978.

geographic regions, and within or outside SMSA’S by the

sum of the reciprocals of the probability of selection for

examined sample persons in the same income, age, region,

and SMSA groups. The percent distribution of the nonresponse adjustment factors is shown in table III.

● Poststratz~cation by age, sex, and race. The estimates were

ratio adjusted within each of 76 age-sex-race cells to independent estimates, provided by the U.S. Bureau of the

Census, of the population as of March 1, 1978, the ap

proximate midpoint of the survey. The ratio adjustment

used a multiplication factor in which the numerator was

the U.S. population and the denominator was the sum of

the weights adjusted for nonresponse for examined persons.

This ratio estimation process brings the population estimates into agreement with the U.S. Bureau of the Census

estimates of the civilian noninstitutionalized population of

the United States, and, in general, reduces sampling errors

of NHANES II estimates.

Talie 111. Percant distribution of the nonresponse adjustment

factors: National Health and Nutrition Examination Survey,

1137&80

Size of factor Percent distribution

TotsI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0

1.00-1 .24. . . . . . . . . . . . . . . . . . . . . . . . . . . . 26.8

1.25 -1,49, . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.8

1.50 -1,74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.9

1.75 -1.99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4

2.010-2 .49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2

2.50-2.99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9

Nonresponse bias

In any health examination survey there exists the potential

for three levels of nonresponse: (1) household interview nonresponse, (2) examination nonresponse, and(3) item nonresponse.

Household interview nonresponse is defined as those sample

42
persons who do not complete the household medical history

questionnaire. Examination nonresponse is those sample persons who initially respond to the household demographic questions and some or all of the medical history questionnaire but

who subsequently do not come to the examination center for an

examination. Item nonresponse results from sample persons

who do not complete some portion of either the household interview questionnaires or the examination protocol, or, to a small

degree, results from loss of blood specimens during shipment

and processing.Intense effortswere undertaken duringNHANES

II to develop and implement procedures and inducements that

would reduce all types of nonresponse and thereby reduce the

potential for bias in the survey estimates. These procedures are

discussed in “Plan and operation of the second National Health

and Nutrition Examination Survey, 1976-80, “Vital and Health

Statistics, Series 1, No. 15.14

In NHANES II, 9 percent (table I) of sample persons refised to give medical history interviews and, despite intense

efforts, 20 percent gave medical history interviews but refhsed

to be examined. Overall, 27 percent (table I) of the 27,801 persons selected for NHANE S II were not examined. However, a

comparison of the 1976 NHIS5S and NHANES 1159suggests

that there is not a large nonresponse bias in some health-related

variables because of the close agreement on selected interview

items in NHANES II data with comparable items in the 1976

NHIS data. The 1976 NHIS data were used for the comparison because that survey included questions on diabetes (of interest in NHANES II) and because the nonresponse was 4 percent, assumed to be randomly distributed throughout the population.

Evidence from earlier studies also suggests no substantial

nonresponse bias. An analysis of data on examined and nonexamined (but interviewed) persons was done using the first 35

stands of NHANES l.sOIt was found that the two groups were

quite similar with respect to the health characteristics that were

being compared. In another study of examined and nonexamined persons selected for participation in NHANES I, no differences were found between the two groups with respect to

health-related variables.61 In another studysz factors relating to

response in cycle I of the National Health Examination Survey

NOTE: A Iist of references folIows the text.

of 1960–62 were investigated. It was found that 36 percent of

the nonexamined persons in that survey viewed themselves as

being in excelle,lt health compared with31 percent of examined

persons. A self-appraisal of being in poor health was made by

5 percent of nonexamined persons and by 6 percent of those

who were examined.

In a different study of cycle 163comparisons between two

extreme groups-those who participated in the survey with no

persuasive effort and those who participated only after a great

deal of persuasive effort-differences between the two groups

generally had little effect on estimates based on numerous selected examination and questiomaire items. This was interpreted as evidence that no large bias exists between the two

groups for the items investigated and was offered as tkther

support for the belief that there is little bias introduced to the

findings because of differences in health characteristics between

examined and nonexamined persons.

All NHANES II sample persons ages 6 months-6 years

and a half-sample of those ages 7–74 years were to have had

blood lead determinations. However, 39.3 percent of these

sample persons had missing lead values due to nonresponse at

various stages of participation in the survey. The rate of nonresponse was greater among preschool-aged children than

among youths or adults (table IV). About half(5 1.0 percent) of

the children ages 6 months–5 years compared with 28.6 percent of persons ages 6–17 years and 35.7 percent of adults ages

18–74 years had no blood lead determinations. Among medically examined persons in the lead subsample (table V), those

with missing blood lead values were randomly distributed by

demographic (other than age) and socioeconomic categories.

Description of exclusions and of

respondents pertaining to tests for

lead poisoning

Blood lead data from blood specimens drawn by fingerstick

(pricking of the fingertip) and from extreme cases of lead exposure (blocd lead values of 70 micrograms per deciliter (pg/

dl) or more) were excluded from computations of national estimates. A description of blood lead levels for persons receiving

fingersticks is given in table VI. Seventy-five percent of the 113

children with blood lead values who received fingersticks were

Table IV. Non response among sample persons 6 months-74 yaars in the Iaad subsample by age: National Health and Nutrition Examination

Survey, 1976-80

Number of sample persons Percent of

sample Percent of

Exemined but missing persons examinees

blood lead values in the in the

lead lead

Refused subsample subsample

to give Blood without without

In lead inter- Not inter- Not

Age

blood specimen lead lead

suhsample vie wed vie wed Exammed examined Total specimen drawn~ va!ues values

Alleges . . . . . . . . . . . 16,563 15,179 1,364 12,288 2,891 2,239 1,197 1,042 39.3 18.2

6 months-5 years , . . 5,069 4,876 193 4,118 758 1,634 988

6-17 years . . . . . . . . . 2,413 2,261

646

152

51.0

1,967

39.7

294 245 122 123

18-74 years . . . . . . . . 9,081 8,042

28.6

1,039

12.5

6,203 1,839 360 87 273 35.7 5.8

1By venipuncture or fingerstick.

43
Table V, N on response smong exemined persons 6 monthe–74 years in the lead sub sample by aga, reca, eex, income, and degree of urbanization: National Health and Nutrition

Examination Survay, 1976-80

Age

6 months-74 years 6 months-5 years 6-17 years 18-74 years

Examined persons Examined persons Examined persons Examined persons

with missing with missing

Number of lead values

with missing with missing

Number of lead values Number of lead values

persons

Number of lead values

persons

Demographic variable

persons persons

examined Number Parcent examined Number Percent examined Number Percent examined Number Percent

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Race

White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sex

Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Annual family income

Under $6,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$6,000–$14,999 . . . . . . . . . . . . . . . . . . . . . . . . . .

$15,000 or more. . . . . . . . . . . . . . . . . . . . . . . . . . .

Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . .

Degree of urbanization

Large urbanl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Smaller urbsnz . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Rural . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12,288 2,239 18.2 4,118 1,634 39.7 1,967 245 12.5 6,203 360 5.8

10,253

1,737

298

1,806 17.6

367 21.1

66 22.1

3,264

723

131

1,311 40.2

269 37.2

54 41.2

1,616

313

38

192 11.9

48 15.3

5 13.2

5,373

701

129

303 5.6

50 7.1

7 5.4

6,123

6,165

1,119 18.3

1,120 18.2

2,143

1,975

840 39.2

794 40.2

1,022

945

119 11.6

126 13.3

2,958

3,245

160 5.4

200 6.2

2,291

5,082

4,509

406

404 17,6

994 19.6

75B 16.8

83 20.4

752

1,876

1,368

122

281 37.4

739 39.4

562 41.1

52 42.6

26B

780

852

67

37 13.8

107 13.7

91 10.7

10 14.9

1,271

2,426

2,289

217

86 6.8

148 6.1

105 4.6

21 9.7

2,993

4,805

4,490

5B3 19.5

869 18.1

787 17.5

949

1,647

1,522

391 41.2

639 38.8

604 39.7

483

721

763

69 14.3

81 11.2

95 12.5

1,561

2,437

2,205

123 7.9

149 6.1

88 4.0

11 million or mora parsons.

‘Fewer than 1 million persons.
Tabla V1. Blood lead determinations from specimens collected by fingersticks in children 6 months-7 years, by race: NationaI Health and

Nutrition Examination Survey, 1976-80

Number Standard

Rece examined Mean devietion Mode Madian Minimum Maximum Skewness

Blood lead level in micrograms per deciliter

Allracesl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 24.8 15.4 18.0 22.2 7.0 116.0 3.5

White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 23.2 17.6 18.0 19.0 7.0 116.0 3.7

Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 28.3 8.0 27.0 28.0 12.0 47.0 0.1

1Includes data for races not shown separately.

under 3 years of age. Table VII shows the characteristics of

three persons receiving venipunctures who had blood lead values greater than 70 pg/dl. Each of these three individuals was

referred to his personal physician for medical attention.

The distribution of blood lead levels for examinees ages 6

months–5 years according to responses to medical history questions about previous tests for lead poisoning is presented in

table VIII. Approximately 16 percent of 123 exarninees who reported being tested for lead poisoning had blood lead levels equal

to or geater than 30 pg/dl. Of these 20 exarninces, only 6 reported that the test indicated they had lead poisoning or high

lead levels. Five of these six examinees were treated for lead

poisoning. The blood lead levels of the respondents at the time

they were previously tested for lead poisoning were not reported.

Subsequent to constructing tables 1–11 and the release of

a public use data tape, codes on 7 of the 2,372 examined

children 6 months-5 years of age were changed-3 from venipuncture to fingerstick and 4 ffom fiigerstick to venipuncture.

The overall findings and conclusions were not affected by these

coding changes. The data listed below are those of the 7 cases

and are offered to help users of the data tape should they wish

Table VII. Characteristics of three persons with blood lead values greater than 70.0 pg/dl who received venipuncture National Health and

Nutrition Examination Survey, 1976-80

Demographic factors

Age in Family Degree of

Blood lead value years Sex Race income urbanization

76. O~g/dl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Male 81ack Under $6,000

80. O~g/dl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Rural

42 Male White $15,000 or more Large urbanl

90. Opg/dl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Male Black Under $6,000 Smaller urbanz

I 1 million or more persons.

2FeWer than 1 million persons.

NOTE: pgldl = micrograms per deciliter.

Teble Vlll. Summary of history of being tested and treated for lead poisoning for children 6 months-5 years, by blood lead level: National

Health and Nutrition Examination Survey, 1976-80

PbB Z 30 205 PbB <30 PbB <20

Medical histoty items Totaf Number Percent Number PerCant Number Percent

Nottested for lead poisoning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,226 96 4.3 453 20.4

Tested for lead poisoning .,...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1,677 75.3

123 20 15.6. 42 34.4

How long ago tested:

61 50.0

O-3 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 7 7

4-6 months, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12

12 1 7 4

7-9 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4 4

10-12 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

2- 2

l-4years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 8 22

Test results positivel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

41

19 6 5

Treated for lead poisoning, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8

9 5 2

How long ago treated:

2

O-3 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1

4-6 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2

l-3 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2 2 2

1Indicated child had lead poisoning or high lead levels.

NOTE: 2 = equal to or greater than.

< = equal to or less than.

< = Ieaa than.

45
to generate similar tables:

● Codes changed from venipuncture to fingerstick

Sequence no. 02618: blood lead level =20 pgldl

Sequence no. 03678: b!ood lead level= 20 pgldl

Sequence no. 05053: blood lead level =20 ~g/dl

. Codes changed from fingerstick to venipuncture

Sequence no. 02025: blood lead level =24 pgjdl

Sequence no. 08295: blood lead level =20 ~g/dl

Sequence no. 08310: blood lead level = 11 pg/dl

Sequence no. 08312: blood lead level = 8 pg/dl

Limitations of the data

Rigorous quality control methods were implementedthroughout specimen collection and processing and in data processing

to insure validity and accuracy of the results reported. However, there are some factors that might affect the data. Foremost is the relative imprecision of a measurement or measurement error. Based on an analysis of the quality control pools,17

the coefficients of variation for the laboratory methods used are

approximately 15.0 and 12.0 percent for control pools with

low (less than 30 pg/dl) and high (30 pg/dl or more) mean

lead levels, respectively. The potential effect of measurement

error on population estimates is discussed in appendix II.

A possible logistical factor indirectly influencing the blood

lead data is the itineray of the MEC’S. To minimize the effects

of adverse weather conditions on response rates, MEC’S were

set up in the Northern States during the summer and more

Southern States during the winter. The potential environmental

effects on blood lead levels associated with seasonalityc4 and

geographic location may be confounded, to some undetermined

degree, with those associated with degree of urbanization of

place of residence. For this reason, the effects associated with

seasonality were taken into account in the regression analysis

of the chronologicaltrend in blood lead levels.(See appendix IV.)

Measures of variability

Because the statistics presented in this report are based on

a sample, they will differ somewhat from the figures that would

have been obtained if a complete census had been taken using

the same survey instruments, instructions, interview and examination personnel, and procedures. The probability design of

this survey permits the estimation of standard errors and standard deviations that are appropriate for the design and weighted

estimates shown in this report.

Standard errors and standard deviations are distinct concepts. The standard error is primarily a measure of the variation

inherent in the process of estimating a population mean from a

sample mean. As calculated for this report, the standard error

also reflects part of the variation that arises in the measurement

process. It does not include estimates of any bias that might be

contained in the data. The chances are about 68 out of 100 that

NOTE: A list of references follows the text.

an estimate based on a sample using the same procedures and

in~tmments would differ from the value obtained from a,Corn.

plete census by less than the standard error. The chanc~s are

about 95 out of 100 that the difference would be less than twice

the standard error and about 99 out of 100 that it would be less

than 2% times as large.

The estimates of standard errors in the text and detailed

tables were calculated using a Taylor series linearization

method.24This process approximates the varh+mceof statistics,

for example, means and proportions, using the first two terms

of a Taylor series expansion. If the higher order terms of the

expansion are negligible and the sample is of a reasonable size

for the domains of interest, then this approximation provides

variance estimates as reliable as those from the pseudoreplication

method adapted for use in the analyses of NHANES II

data.65’66It should be noted that the estimates of standanjl errors

are themselves subject to errors that may be large if the number

of cases or the number of PSU’S involved in the calculation of

variances are small.

The standard deviation, on the other hand, is a measure of

the dispersion of the observations in a sample, and is usefid in

describing how an individual observation compares with the

mean of the sample. As calculated for this report, it also reflects part of the variation that arises in the measurement process. If the data are normally distributed (that is, Gaussian),

then one standard deviation from the mean (in either direction)

encompasses approximately 68 percent of the distribution, two

standard deviations, about 95 percenc and 2% standard deviations, about 99 percent.

The estimates of standard deviations presented in the tables

were calculated by using the pseudoreplication method, a balanced half-sample replication technique that is based on variability among random subsamples of the total sample.65J6

12ata reliability

The criteria for reliability of estimates shown in this report

consisted of the following (1) that the sample size, on which

the estimate is based, is at least 25 persons and (2) that the

estimated coefficient of variation (i.e., the standard error of the

mean divided by the mean) is less than 30 percent. Thus if the

sample size was too small or ifthe variation regarding thb mean

was too large, an asterisk was placed next to the value on the

table. This estimate is considered neither precise nor stable

enough to meet reliability standards; however, the values are

shown to give an impression of the observed distribution and to

permit users to combine data into useful categories.

Tests of significance

Hypothesis testing and tests of significance were conducted

usingtwo computer programs, SURREGR2Sand GENCAT.26,~T

The former was used for regression analysis and the latter for

generalized categorical data analysis. All tests accounted for

the complex survey sample design. Unless otherwise specified,

tests were conducted using a probability level of 0.05.

46
Appendix II

Statistical analysis of the

effects of analytic error on

national estimates

The effect of analytic error (in blood lead determination)

on national prevalence estimates of elevated blood lead values

(30 ~g/dl or more) from the second National Health and,Nutrition Examination Survey (NHANES II) is the topic of this

appendix. The predicted effect of analytic error (due to sampling

of blood and laborato~ measurement error) on NHANES II

national estimates is compared with that predicted from computations presented by Lucas.67Also, potential bias in estimating analytic error associated with systematic deviations in the

NHANES II quality control blood lead measures is evaluated

and discussed.

Background

Following the lognormal model and definitions of parameters in the model used by Lucas,67the total population variance

of blood lead levels can be partitioned into two major components: the population variance of the true blood lead values

~ and the analytic variance u:. The variance of the true blood

lead values is composed of individual-to-individual variation

in blood lead levels and variation in an individual’s blood lead

level over time. The analytic variance includes variation in

blood lead levels attributable to the sampling of an individual’s

blood at a fixed point in time ~ and to laboratory measurement

error d~. Lucas67 gives a more detailed description of these

variance components.

The degree to which analytic error influences national estimates of the percent of persons with blood lead levels of 30.0

@dl or more from the NHANES data was examined using

two different statistical techniques. The first technique (referred

to as analysis no. 1) was a semiparametric approach using a

discriminant function to estimate the probability of misclassification.68 This procedure was used to estimate classification

probabilities above and below the threshold (30.0 pg/dl WB)

for each measured blood lead level from venous blood specimens collected in NHANES IL The second technique (referred

to as analysis no. 2) was the parametric approach described by

Lucas.67 This latter procedure involved computing Z values

and the correlation between measured and true blood lead values.

Estimates of classification probabilities above and below the

threshold were then obtained from tables of the bivariate normal

distribution.

For both analyses, it was assumed that the relationship between measured blood lead levels and true blood lead values

NOTE: A Iist of referencesfollowsthe text,

can be described by a bivariate Iognormal distribution (a bivariate normal distribution using the natural log blood lead

values).

Model used for analysis

Following the lognormal model used by Lucas,67 it is assumed that the relationship between measured blood lead values

and true blood lead values can be described as a bivariate lognormal distribution. Thus, if

Y = in (true blood lead)

X = in (measured blood lead)

s = in (analytical error)

x= Y+&

where Y and .sare independent with Y - N (pt, a:); where Pf

and u? are the population mean and variance of the true blood

lead values, respectively, and e - N (O, a:). It follows immediately that

Estimation of means and variance

components horn N HAN ES II blood

lead data

Estimates of population mean and the total population

variance (for example, a: + da ) for selected groups are presented in table IX. These estimates were computed using

weighted natural log transforms of the measured blood lead

values. Population variances were estimated using a variant

developed by Ron Forthofer and Robert Casady69 of the balanced repeated replication (BRR) strategy described by

McCarthy70 and Kish and Frankel.71 This procedure yields

unbiased estimates of population variance.

For his computations, Lucas67partitioned the analytic variance u: into WO components a sampling component denoted

by u: and a measurement component denoted by a:. For this

study, the measurement error u; was fi.u-therpartitioned into

two components. The fust, which we denote u;, measures variation between mean levels of measured blood lead on a day-today basis, while the second, denoted o~.~measures the variation

47
Table IX. Estimates used in analyses nos. 1 snd 2: United States,

1976-80

Estimated population

parameters

Selected race. sex, and age groups L

6; + 6: $

All persons 6 months-74 yearsl . 2.553 0.1670 0.1462

All children 6 months-5 yearsl . . . . . . 2.699 0.1509 0.1301

White . . . . . . . . . . . . . . . . . . . . . . . . . . 2,636 0.1334 0.1126

Black . . . . . . . . . . . . . . . . . . . . . . . . . . 2.974 0.1350 0,1142

Allpersons 6-17 yearsl ..,..... . . . . . 2.460 0.1368 0.1160

Men, 18-74 yearsl . . . . . . . . . . . . . . .,, 2.759 0.1361 0.1153

Women, 18-74 yearsl . . . . . . . . . . . . . 2.397 0.1439 0.1231

1Includes races other than white or black.

NOTE ~t = population mean of the true blood lead valuea in units of the

natural logarithm of tha blood lead level.

~ = population variance of the true blood lead valuea in units of the

natural Iogsrithm of the blood lead level.

~ = anelytic variance in units of the natural logarithm of the blood lead

level,

of determinations within a day. As the measured blood level

reported for NHANES II is the average of two determinations

made within a day, the appropriate model is

Using the lead data from the high and low blind quality control

blood pools, our estimates of the above component parameters

are 6; = 0.01012 and i%r = 0.01 385; the estimate of u; is,

therefore, 6;= 0.01704.

Unfortunately, only one sample of blood was taken from

each NHANES II respondent so it was impossible to estimate

the parameter u; directly from the NHANES 11data. However,

the blood sampling methodology used by Griffin et al.72 was

similar to the venipuncture method used in the NHANES II.

An analysis of the Griffin data, using the methodology developed by Snee and Smith73 provided an overestimate (the expected value of the estimate contained both the time compnent and the sampling component) of the sampling variance

component. The overestimate of cr~based on Griffin’s data is

~; = 0.00379.

Assuming the variance component resulting from sampling

for NHANES II is similar to that for the Griflln study~2 the

estimate of analytic variance d: for NHANES II is

= 0.00379 + 0.01704

= 0.02083

Subtracting the above estimate from the total population variance estimates yields the estimates of ~ shown in table IX.

Computational methods of analysis no, 1

Given the assumptions of the model, the true and measured

values, Y and X, respectively, are bivariate lognormal with a

correlation of ull~~~ Therefore, the expected true blood

lead value given the measured value X can be expressed as

r+

-E(Y/x) “ l-q + ~d(~ – I-4)

t a

and the conditional variance is

( -) Var(Y/X)=* 1 –

Using these formulas the true probability that a measured

blood lead level exceeds the given threshold of 30.0 pg/dl of

whole blood can be computed as the area under the normal

cwve with mean E( Y/X) and variance Var (Y/X).

In figure I the correction for misclassification error caused

by analytic variance is illustrated. Case 1 represents the probability of misclassification of a conditional expected blood lead

level that lies above the threshold value. With the assumption

thatthe distribution of analytic error about the conditional

mean is normal, and using the conditional estimate of the variance (Var (Y/X)), then the area under that normal curve that

Probability of a Probability ‘of a

false negative

t

E(y/x)

Threshold

Cese 1: Computing probability of true exceedence with expected pogitive

Probability of a Probability of a

true negative

E(y/x) ?’

Threshold

Case 2: Computing probability of true exceedence with expected

negative

Figure 1, Estimating probabilities of elevated blood lead levels

NOTE: A list of references follows the text. from observed levels

48
lies to the Iefi of the threshold is an estimate of the probability

that the examinee’s blood lead value is observed to be less but

is truly greater (OLTG) than the threshold. This is often referred to as the probability of a false negative. The area under

the normal curve that lies to the right of the threshold is an

estimate of the probability that the examinee’s blood lead value

is observed to be greater and is truly greater (OGTG).

The opposite occurs when the conditional expected blood

lead level lies below the selected threshold (case 2, figure I).

The area under the normal curve to the left of the given threshold is an estimate of the probability that the examinee’s blood

lead value is observed to be less and is truly less (OLTL) than

the selected threshold. The area under the curve to the right of

the threshold is the probability that the examinee’s blood lead

value is observed to be greater but is truly less (OGTL) than

the threshol~ this is commonly referred to as a false positive.

After these probabilities were computed for each measured

blood lead value, they were multiplied by the NHANES II

sample weights and summed within each of the four possible

categories OLTG, OLTL, OGTG, and OGTL. Subsequently,

an estimate of the percent of persons in the population with

blood lead levels truly greater than the threshold of 30.0 @dl

(after accounting for the effects of analytic error) was obtained

by

OLTG + OGTG

OLTG + OLTL + OGTG + OGTL x 100

Computational methods of analysis no. 2

Using the assumptions of the model and the estimated

values of the parameters, estimates of the percent truly greater

than a threshold of 30 pg/dl were obtained using the method

proposed by Lucas.67

Results

The results of analyses nos. 1 and 2 were very similar.

These results are presented as the estimated percent truly greater

(than a threshold of 30 pg/dl) in table X. In general, the percent

truly greater than this threshold was approximately 24 percent

less than the prevalence of blood lead levels of 30 pg/dl or

more estimated from the weighted NHANES II data. This

effect is substantially less than that predicted by Lucas.67For a

population with a geometric mean of 15 @all, Lucas predicted

95 percent false positives (observed greater but truly less thrm

a threshold of 30 pg/dl) and 0.04 percent false negatives (observed less but truly greater than a threshold of 30 pgJdl).

Overall, this study predicted about the same percent of false

positives but substantially more (1.4 percent) false negatives.

While the lognormal model proposed by Lucas67may have

general application for studies involving blood lead determination, the various parameters in the model depend upon factors

inherent to the particular study of interest. For example, the

sampling variance components are expected to differ using the

fingerstick versus the venipuncture method for blood collection.

Likewise, the measurement variance component might be quite

different depending on the laboratory method of blood lead

determination; that is, atomic absorption spectrophotometry,

dithizone, anodic stripping voltammetry or isotopic dilution

mass spectrometry.

NOTE: A list of references folIows tfre texL

Table X. Blood Iced levels of persons 6 months-74 years, with mean and standard deviation of the mean, percant of persons with Ievals of

30 pg/dl or more, and estimated parcents of persons with levels above the threshold of 30 ~g/dl after accounting for analytic arror, by selected

characteristics: United States, 1976-80

Analysis Analysis

Estimated Arithmetic Geometric no. 1: no. 2:

population Estimated3 estimated estimated

in Number Standard Standard

Characteristic thousands~

prevalence of percent percent

ex%mined2 Mean deviation Mean deviation PbB >30.0 ,ug/dI truly greater truly greater

All persons,

6 months-74 years5. . .

All children,

6 months-5 years5. . .

White . . . . . . . . . . . .

Black . . . . . . . . . . . . .

All persons,

6-17 yaars5 . . . . . . . .

Men, 18-74 years5. . .

Women,

18-74 years5. . . . . . .

Micrograms par daciliter Percent & SEP

203,554 9,936 13.9 6.05 12.8 1.51

16,862 2,376 16.0 6.56 14.9 1.48

13,641 1,876 14.9 5.60 14.0

2,584

1.44

420 20.9 8.18 19.6 1.44

44,964 1,720 12.5 4.68 11.7 1.45

67,555 2,798 16.9 6.76 15.8 1.45

74,173 3,045 11.8 4.64 11.0 1.46

1.9 * 0.2 1.4 1.5

4.0 * 0.5 2.9 2.9

2.0 * 0.3 1.3 1.3

12.2 *1.5 10.6 11.3

0.5 * 0.2 0.3 0.3

4.2 * 0.5 3.1 3.3

0.5 * 0,2 0,3 0.3

‘At the midpoint of the survey, Merch 1, 1978.

2With lead determinations from blood specimens drawn by venipun~tur~.

3From the weighted NHANES II blood lead date.

4Stendard error of the percent.

51ncludes data for races other than white and black.

NOTE ~g/dl = micrograms per deciliter.

49
It is inappropriate to apply the computations of Lucasb’ to

estimate the effect of analytic error on NHANES II national

estimates. The classification probabilities above and below

given thresholds were computed using variance components

estimated from the NHANE S II data, whereas Lucas used

variance components estimated from studies 73.74 in which

the protocols differed from one another and from that of

NHANES H.

The results of analyses nos. 1 and 2 agreed with Lucasb’

concerning the effects of analytic error in relation to the magnitude of the geometric mean. Analytic error had less effect on

the prevalence of blood lead levels of 30 pg/dl or more for the

population subgroups with higher geometric mean values. For

instance, for black children (with a geometric mean of 19.6 ~g/dl)

and for white children (with a geometric mean of 14.0 pg/dl)

(table X), the estimated percents truly greater than 30 ptg/dl

from analysis no. 1 were approximately 87 and 65 percent of

the prevalence of blood lead levels of 30 pg/dl or more, respectively.

NOTE: A list of references follows the text.

Examination of potential bias in estimating

analytic error

Analytic error can result from lack of quality control at

four different stages of lead analysis: (1) collection and pfeparatiion of the blood sample prior to laboratory assessment;

(2) laboratory manipulation of the blood sample, physically

and chemically, prior to delivery to a given instrumentation

system; (3) instrumentation, quantitation, and calibration

methods used to determine lead levels; and (4) establishment

of relevant criteria for accuracy and precision through in~emal

or external quality assurance checks, or both. Sources of contamination and error in determining lead concentrations in blood

specimens at each of these stages are discussed elsewh&e.75

The NHANES II lead analysis was tightly controlled in each

of these areas according to a very strict protocol.zl If there

were systematic errors caused by deviation in the protocol they

would show up in an examination of the blind quality control

blc)od samples.

To investigate the potential for systematic changes due to

analytic error over the course of the NHANES II blood lead

determinations, the blind quality control samples from the low

+

+

+

+

+

+

+ +

18 + ++ ++ +++ + +

&

%=

u + 4+++ -tHtitt+*+F+ + i++ i+st

~

:

~ 16 ++ ++++ +W +++SI- it+ W’tE i-l- l-++++!-+ *

E

P it ++++++ *+++

m

++IH+ H-+1+* .s-!+ W’+*** +!’+++ ++

p

v

~ 14 ,- +* *+-I+ +H-*++F+ +HH’Hl+ 4++ + +tH+H+W-tll-w W+ ++*+ + *

.s

~ *++ ++ *

al

* * ++ +++H——a—H+s— ++ **+**++ +++ +tt+ it++

>

0)

u 12 ++++++*++++ -HI’W-H+* !++* -IH+F++* -11--H-H- + tHt *+ +-It

m

2

-0 + + +-S-* +tt + ++ ++4++ ++ ++++ ++ *+

~

G

10 + +-H++++ ++ +++ i++++ *+ +-l+

+++ + + + + +

8 + + + +

+ + +

6 +

(,, .,1. ”.,l. ””’1””’” 1”” “’1”’’’ 1’’’’ 1’’’’ 1’””1 “’’’ 1”’’’ 1’”’’ 1””” ”l ””” “1’” ””l’”’”l”’’” 1”- ~’

16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54

Time!

11 unit =28 days.

Figure Il. Scattergram of blood lead levels determined from the low quality control blood pool by chronological time: National Health and

Nutrition Examination Survey, 1976-80

50
and high bovine blood pools were examined with respect to a

time variable. The time variable was defined to correspond to

the chronology of collection of NHANES II blood samples

analyzed in the same analytical (laboratory) run as the respective

blind control sample. Figures II and III show scattergrams of

the blood lead values by time for the low and high blind pools,

respectively. (Note that blind quality control data from approximately 12 months of the NHANES II are not presented because

of initial technical difficulties in labeling the blind specimens to

be indistinguishable from the NHANES II specimens.) Estimates of the effect of analytic error on national estimates presented in the previous section could be biased if the average

blind pool values changed significantly with time or if the

measurement variance was heterogeneous over time. A statistical analysis of the blind control data within each pool suggested that neither the mean log blood lead values nor the estimates of measurement variance were significantly different

among three selected time periods at the 0.05 level of probability. Table XI shows the mean log blood lead values, standard

deviations of the means, and measurement variance estimates

for three chronological time periods for the low and high blind

pools.

In addition, the blind quality control lead values (untransformed) were examined with respect to time using regression

analysis. Because the observed blood lead data from the low

and high pools were approximately normally distributed, lead

values in each pool were z transformed; that is (lead value – lead

pool mean)/(lead pool standard deviation). The resulting data

from the two pools, each having a mean of zero and a variance

of one, were combined, and regressions of z on time alone and

z on time and time-squared together were performed. When the

linear term time was t%alone, there was no significant trend of

transformed lead values (table XII).

Regression of z on the linear and quadratic time variables

suggested a statistically significant curvilinear relationship between z and the chronological time variable (table XII).

However, the regression coefficients associated with the linear

and quadratic time variables were relatively small in magnitude.

Also, less than 2 percent (R2 = 0.0186) of the total variability

of the transformed lead values was explained by the model.

The association between time and the blind quality control

lead values in relation to the chronological downward trend in

the NHANES II blood lead data are discussed elsewhere.4

Findings reported in that paper indicate that the statistically

significant 37 percent overall reduction in mean NHANES II

blood lead levels from February 1976 through February 1980

NOTE: A list of references follows the text.

37.5 -

‘+

u

+

++

++

‘s--l+ +-+

++++

++ +-n-u

+ +-l-k+ +s-

-s+l- ++-9+

++ + +++-

i++

+-+++

+ ++++

4-

+

+

+

-l+

‘H+

i++

+-+ ++

++!-+

i+ *+

+—H+H+HU

-s+

-U+++

++

+ ++

+-+

+

+

‘4

++

+ +-s-s-

‘+ ++ +

++’+ + ++++ i- iifs.

+-s- +s+ ++++ +HS++

++++ + + ++H-S+ +itif-1+

+++-+ +*+ U++*

+l-++++Hl+ +l-++s+l-

+* +++ *++* +*++

+-+ ++++-+ s-++-+

++ ++-+s+-s+s-+ -s-4+

++ 4++

++ i- +

+

++

+

+

+

+-+

+

+

+

+ -!-4+.++

++-s-+ + +++

+s++++t+

-H++ -HI+*

-I++S+++ *-H+

it+ii+t++l+#

+ +.i+lt+s+

+!+-+*+++

4-+1+ +-S.

+ ++

4-+ +++

+++

+

+* -It

++

+

++ ++ +

+1- *+-w-

-1++++1-

+’-s. +

+!++!+*+

-1-i++++

it i+ +-I+

it +

+ +

*++ +

+ +

+ ++

+

+

+

+

*

+-4s.

+it

4r+-li-

**

+

*

+

+

+

+

I.=..l....,....l.,.=l .,.1 . . . . 1 . . ..1....1. . ..1 . . ..s . ...1....1.. ,.i..,.l.=..,..,.l.=, . 1 . . . . 1 . . . . . . . . . . . . . . j

12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54

Timel

11 unit= 28 days.

Figure 111, Scattergram of blood lead levels determined from the high quality control blood pool by chronological time: National Heath and

Nutrition Examination Survey, 1976-80

51
TableXl. Naturel logarithm of blood lead levels for the blind quality control pools with mean, standard deviation of the mean, and estimated

measurement variance by chronological time periods: National Health and Nutrition Examination Survey, 1976-80

Low blind pool High blind pool

Time period~

Standard

Number

Standard

Mean deviation s. Number Mean deviation dm

In PbB in #g/all In PbB in pg/dl

First . . . . . . . . . . . . . . . . . . . . . . . . 72 2.60 0.178 0.0215 144 3.22

Second . . . . . . . . . . . . . . . . . . . . . 266 2.61

0.132 ID.01 18

0.169 0.0208 246 3.24

Third . . . . . . . . . . . . . . . . . . . . . . . 188 2.56

0.118 (0.0103

0.177 0.0207 210 3.24 0.146 0.0162

lln 28-day periods from the beginning (time = 1) to the end [time = 52.4) of NHANES Il.

13< first <25

25< second <40

40< third <52.4

NOTE: &m = & + 0$/2, where m = measurement; r= run; and d= determination.

In= natural logarithm.

PbB = blood lead level.

l&#dl = micrograms per deciliter.

< = qual to or Ieaa than.

< = Iesa than,

Table Xl 1. Reeults of regression analysis of z on a chronological time variable: National Health and Nutrition Examination Survey, 1976-80

A. Dependent variable= z; independent variable = time; R-square = 0.0000

Degrees of Sum of

Source freedom squares

Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0.000

Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,124 1,124.000

Ctotel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,125 1,124.000

Degrees of Parameter

Variable freedom estimate

Intercept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0.000

Time . . . . . . . . . . . . . . . . . . . . . . . . ...!.. . . . . . . . . . . . . . . . 1 -0,000

B. Dependent variable = z; independent variables = time and time squared; fi’-square = 0.0186

Degrees of Sum of

Source freedom squares

Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 20.933

Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,123 1,103.067

Ctotal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,125 1,124.000

Degreas of Parametar

Variable fraadom astimate

Intercept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 –1 ,291

Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0.084

Time squared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -0.001

Mean

square

0.000

1.000

. . .

Standard

error

0.1070

0.0029

Mean

square

10.462

0.982

error

0.2992

0.0185

0.0003

F valua

0.000

. . .

t for Ho:

parameter = O

0.005

-0.006

F valua

10.656

. . .

. . .

t for HO:

parameter = O

-4.315

4.558

-4.616

Probability

>F

0.9954

. . .

Probability

> Id

0.9956

0.9954

Probability

>F

01.or)r)l

. . .

. . .

Probability

5 Id

0.0001

0,0001

()!0001

NOTES z = (blood lead value minus poo( mean) /standard deviation of the pool mean.

Time corresponds to the chronology of collection of blood specimens analyzed in the sama analytical labo:ato~ runs.

> = greater than,

It]= sbsolute value oft.

is not attributable to the nominal systematic error in the blind

quality control blood lead determinations.

Summary

While the lognormal model assumed by Lucas67could have

general application to studies involving blood lead determinations, estimation of the various parameters in the model depends

upon the sampling, measurement, and quality control protocols

inherent in the study of interest. Therefore, to determine the

possible effects of analytic error (due to sampling of blood and

laboratory measurement error) on NHANES II national estimates, it was imperative to estimate these parameters using the

NOTE: A list of referencesfollowsthe text.

NHANES II data. The misclassification probabilities of blood

load values above and below given thresholds reported by

L,ucas67were based on parameters in the model estimat~d from

blood lead data obtained in studies with protocols notably diffkrent from NHANES II. Thus, the direct application of the

misclassification probabilities presented by Luc:#7 to

NHANES II national estimates is inappropriate.

The Lucas67model was applied using appropriate parameter

estimates computed from the NHANES II data. The results

show that accounting for analytic error could reduce the’overall

prevalence of elevated blood lead leveis from NHANES II by

2!4percent, as opposed to the 90-percent reduction predicted

using Lucas’ computations.

One source of analytic error not explicitly parameterized

in the Lucas model is systematic deviation in laboratory de52
terminations. Most protocols do not provide for the specific to these NHANES II quality control data resulted in a finding

assessment of this component of analytic error. However, in that systematic errors were minimal. No significant trends in

the NHANES II, evidence of systematic error could be found either mean log blood lead values or estimates of measurement

by examining the blind quality control blood samples that were variance were found across time in either the high or the low

subjected to the survey’s blood lead laboratory determination lead values from blind quality control blood pools.

procedures. The application of statistical regression techniques

53
Appendix III

Demographic and

socioeconomic terms and

dietary and medical history

items

Age—Age was defined as age at last birthday at the time

of the household interview.

Race—The race of each respondent was determined during

the household interview. Race was observed and recorded as

“white,”” black,” or “other.” Other includesJapanese, Chinese,

American Indian, Korean, Eskimo, and all races other than

white and black. Persons of Mexican descent were included

with” white” unless definitely known to be American Indian or

of another race. Black persons and persons of mixed black and

other parentage were recorded as black. When a person of

mixed racial background was uncertain about his or her race,

the race of the father was recorded. Data on other races are not

presented separately in this report but are included in the “all

races” category.

Sex-Sex was recorded by the interviewers and examiners.

Annual family income—The respondent was given a card

listing 12 income categories and was instructed to select the

one that represented his or her total combined family income

for the past 12 months. Respondents were asked to include

income from all sources such as wages, salaries, social security

or retirement benefits, help from relatives, rent from property,

and SO forth.

Degree of urbanization of place of residence—Four urbanization classes were defined, based on the population of the

place in which the examinee resided and, in some cases, on

whether the examinee resided in the central city of a standard

metropolitan statistical area (SMSA). These classes were

(1) urbanized area with a population of 1,000,000 or more, in

the central city of the SMSA; (2) urbanized area with a population of 1,000,000 or more, but not in the central city of the

SMSA; (3) urbanized area under 1,000,000 population or

urban place with a population of 2,500 or more but outside the

urbanized area, either in or out of the SMSA; and (4) rural, including rural areas in extended cities and all incorporated or

unincorporated areas with a population of less than 2,5010.

Season—The four seasons were defined as follows:

Winter . . . . . . . . . . . . . . . . . . . . . . .. December 21-March20

Spring . . . . . . . . . . . . . . . . . . . . . . . ., . . .. March June20e2O

Summer . . . . . . . . . . . . . . . . . . . . . . . . June 21-September 20

Fall . . . . . . . . . . . . . . . . . . . . . . . Septamber 21 -December 20

Geographic region—The 48 contiguous States, the District

of Columbia, Alaska, and Hawaii were stratified into four broad

geographic regions, each of about the same population size.

The compositions of the regions are as follows:

Region States included

Northeast . . . Connecticut, Maine, Massachusetts, Nevb

Hampshire, Rhode Island, Vermont, New

York, New Jersey, and Pennsylvania

Midwest . . . . Ohio, Indiana, Michigan, Wisconsin, Illinois,

Minnesota, Iowa, and Missouri

South . . . . . . Delaware, District of Columbia, Maryland,

Virginia, Kentucky, Tennessee, West Virginia, Alabama, Arkansas, Louisiana, Mississippi, Georgia, North Carolina, South

Carolina, and Florida

West, . . . . . . California, Oregon, Washington, Texas, Arizona, Colorado, Idaho, Montana, Nevada,

Naw Mexico, Oklahoma, Utah, Wyoming,

Alaaka, Hawaii, Kansas, Nebraska, North

Dakota, and South Dakota

Education of the head of household—For each sample person interviewed, questions were asked pertaining to the head of

the household. One such item was the highest grade or year of

regular school that the head of the household attended. For

presentation of blood lead data of children ages 6 months–17

years, three levels of educational status of the household head

were defined. These categories are less than high school, high

school, and college level or equivalent.

Occupation—Occupation was reported by the respondent

during the household interview. These data were later converted

tclnumeric codes by the U.S. Bureau of the Census, based on

the 1970 Census of Population. Alphabetical Index of Industries and Occupations. 76

For analysis of blood lead level in relation to occupation,

LJ.S.workers ages 18–74 years were partitioned into two groups

based on their potential exposure to lead at the workplace.

High and low potential exposure groups were defined using

information on types of occupations with observed potential

exposure to lead from the National Occupational Hazard Survey (NOHS) conducted from 1972 through 1974.68Exarninees

in the second National Health and Nutrition Examination

SWeY repo~inga~cultur~ occupations and those rep$wdnga

selected group of professional and semiprofessional occupations

were excluded from analysis and tables of blood lead data presented by these occupational exposure categories. The former

were excluded because farm-related occupations are not covered under the provisions of the Occupational Safety and Health

FIOTE: A list of references follows the text.

54
Act of 1970 and thus were not part of the National Occupational Hazard Survey. The latter (professionals and semiprofessionals) were excluded because of difilculty in classifying them

as either high or low potential exposure to lead in their work

setting.

Smoking status—Smoking status was derived from questionnaire data reported by respondents, ages 18–74 years, during the household interview. Nonsmokers included those currently smoking neither cigarettes, pipe tobacco, nor cigars at the

time of examination. Ex-smokers are included as nonsmokers.

Smokers include those currently smoking cigarettes, pipe toinclude those currently smoking cigarettes at the time of examination, whether or not they also smoke cigars or pipe tobacco.

Consumption of alcoholic beverages—Information on consumption of alcoholic beverages was obtained during the dietary

interview at the time of examination. Nondrinkers were defined

as those who responded as not having had a drink of beer,

wine, or liquor within 3 months of the time of exam. All other

respondents were classified as drinkers.

Pica and lead poisoning tests—Data on eating unusual

substances and on being tested for lead poisoning were obtained during the household interview. The questions rebacco, or cigars at the time of examination. Cigarette smokers sponded to are shown in figure IV.

19a. Some children eat unusual substances. Does -- eat I

clay, starch, paint, ploster, dirt, or any material ~@ l13Yes

thot might be considered unusuol? I 2❑ No (20)

b. Is it -

I

Yes No

I

Clay? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . !@10 20

Starch? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

~@ II-J 20

Paint or plaster? . . . . . . . . . . . . . . . . . . . . . . . . .

i@ 10

Dirt? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

\@ lU 20

Any other material? - Specify I

26a. Has -- ever been tested for lead poisoning? @ In Yes

I 20N0

!

}

(27)

I

9i-JDK

b. HOW long ogo was -- tested? I

.0/ 218 Years

I

p Months

o D Less than one month

c. Did the results indicate that he had lead poisoning ~@J In Yes

or high lead?

i

2 D No (27)

d. kfos -- ever been treated for lead poisoning? j@JIU Yes

I

2 ❑ No (27)

e. HOW long ago wos -- treated?

~@l Years

o

I 223 Months

I

I o ❑ Less than one month

Figure IV. Questions asked to obtain data on eating unusual substances and an testing for lead poisaning: National Health and Nutrition

Examination Survey, 1976-80.

55
Appendix IV

Statistical analysis of the

chronological trend in the

NHANES 11blood lead levels

Linear regression analysis of the time trend

The computer program SURREGR,29 which accounts for

the complex survey design, was used for regression analyses.

The blood lead values were weighted to represent population

estimates, and those weights were included in the regression

calculations. Regression analysis of NHANES II blood lead

levels on time and the demographic covariates were performed

for all races and in the selected population subgroups defined

by race, sex, and age.

A plot of the mean blood lead levels of all races versus

time (figure 8) suggested that a piecewise (segmental) linear

regression mode178 would be appropriate. Mean blood lead

values were computed as national estimates from data obtained

on 9,933 examinees with blood lead measurements from specimens drawn by venipuncture over the 4-year period of

NHANES II. The time variable was defined as the number of

days from the beginning of the survey (February 20, 1976) to

the date of sample collection divided by 28 (28 days was arbitrarily chosen).

Regression model

The regression model was constructed to fit a line from

time = O through time = 34 and a second line from time = 34

to the end of the survey. The time value of 34 (that is, the 34th

28-day period) was chosen from visual inspection. The statistical formulation of the piecewise regression model was as

follows:

where Yj = natural logarithm (in) of an examinee’s blood lead

value

Xl = number of days from February 20, 1976, to sample

collection date divided by 28

X2= indicator variable: Xz = O if X1 534 and Xz = 1

ifX1 >34

X.= indicator variable for the nti demographic covariate

When Xl <34 (those examined from Februaxy 1976-

September 1978), the expected value of Y given equation(1)

NOTE: A list of references follows the text.

recluces to

E(y)= po+plxl+. ..+pn(xn) (2)

When X1 >34 (those examined from October 1978–

Februa~ 1980), the expected value of Y given equation (1)

reciuces to

In the regression analyses based on equation (1), the coding

for the time variables was as follows:

ORDER = Xl

ORDER1 = (Xl – 34)X2

The coding of the demographic covariates was as follows:

● Race:

FU4CE1 = 1 Blacks

R4CE1 =0 All other races

● Sex

SEX1 = 1 Male

SEX1 = O Female

. Age:

CHILD = 1 TEEN = O 6 months–5 years

CHILD = O TEEN = 1 6 years– 17 years

CHILD = O TEEN = O 18 years–74 years

. Income

INcl = 1 Annual family income less than $10,000

INcl =0 Amual family income greater than or equal

or $10,000

. Urbanization:

RURAL = 1 Area of less than 1 million population

RURAL = O Area of greater than or equal to 1 million

population

● Seasox

WINTER = 1 Winter or spring

WINTER = O Summer or fall

● Region of the country

SOUTH = 1 South and West

SOUTH = O Northeast and Midwest

Twovariable interaction terms were selected for the, model

by prescreening all the possible two-variable interactioti terms

using ordinary least-squares stepwise regression (SAS, MAXR

.56
option) .79Stepwise regression using backward elimination was

also performed retaining variables that remained signitlcant at

the 0.10 level. Both approaches indicated that the following

interaction terms were significant at the 0.10 level:

●

●

●

●

●

●

●

●

AS I: CHILD X SEX1

AS2: TEEN X SEX I

ARl : CHILD X R4CE1

Ail: CHILD XINCI

.412: TEEN X INC1

RUI : IU4CE 1 X RURAL

UNl: RURAL X SOUTH

RW1 : I&4CEl X WINTER

The main effects, plus these interaction terms, were referred to

as the demographic covariates.

The ordinary least-squares prescreening procedure gave a

starting set of variablesfor regression analysiswith SURREGR29

When the starting set of variables were examined using

SURREGR, the significance of some of the variables decreased,

because the variance estimates were generally higher after accounting for the sample design. Therefore, a “manual” backward elimination procedure was performed by running

SURREGR multiple times, dropping the least significant variable from the model on each run until all variables were significant at the 0.05 level. In the process, ORDER and ORDER1

variables and any main effect demographic variables associated

with a significant two-variable interaction term were kept in the

model. The “manual” backward elimination procedure was

applied separately to all races together, blacks, whites, white

males, white females, whites 6 months–5 years, whhes 6– 17

years, and whites 18–74 years. Blacks were not analyzed by

sex and age subgroups due to inadequate sample sizes.

Results from the time trend analysis

The results of the regression analyses are summarized by

population group in table XIII. For each population group, the

model was highly significant and the decrease in blood lead

levels as measured by ORDER and ORDERI was also highly

significant.

The magnitude of the decrease in blood lead levels from

the beginning to the end of the 4-year survey period was estimated in the following manner. First, the average value of each

indicator variable (over the respective population group) was

multiplied by its regression coefllcient and then added to the

intercept to form an adjusted intercept. The resulting equation

then consisted of an adjusted intercept, ORDER and ORDER1.

This equation was evaluated at values of ORDER and ORDER1

that represented the start and end of the survey as natural logarithms. The antilogs of these lead values are presented in

table XIV along with a calculated percent drop over the survey

period. The numbers given in the last column of table XIV

were used to graph the bars in figure 9.

NOTE: A list of references follows the text.

The results shown in table XIV indicate that after accounting for the demographic covariates with indicator variables, a

downward trend in blood lead values is still present and ranges

from 31 to 42 percent.

Linear regression analysis of NHANES II

blood lead levels on a gasoline lead variable

The regression analysis using the national estimates of lead

used in gasoline production was conducted in the same manner

as the time trend analysis, except GASQ (the U.S. Environmental Protection Agency quarterly national gasoline estirnate)~o

replaced ORDER and ORDERI in the model. Preliminary

stepwise regression analysis indicated that GASQ was preferred over the quadratic term GASQ-squared. Separate regression analyses were performed for all races, blacks, whites,

white males, white females, whites 6 months-5 years, whites

6-17 years, and whites 18–74 years. As previously noted,

blacks were not analyzed by sex and age subgroups because of

inadequate sample sizes.

The results of the regression analyses are summarized by

population group in table XV. For each population group, the

coefficient for the gasoline lead variable (GASQ) was highly

significant.

The amount of lead used in gasoline production decreased

by more than 50 percent from the beginning to the end of the

survey. The magnitude of the change in blood lead levels that

can be accounted for by the gasoline lead variable can be calculated in the same manner as was done for ORDER and

ORDER1. An adjusted intercept is determined and the model

equation is then evaluated at the gasoline lead values present at

the start and end of the survey. The results of these calculations are presented in table XVI. The entire analysis was repeated using 6 months’ national gasoline estimates with very

similar results.

Correlation analysis between blood lead level

and lead used in gasoline production

To further evaluate the relationship of lead in gasoline

production to NHANES II blood lead levels, the following

correlation analysis was done. First, a regression model consisting only of the demographic covariates was fitto the natural

logarithm of the blocd lead data. Then, the mean of all the

natural logarithm blood lead levels used in the regression was

added to the residuals from the fit. This procedure gave blood

lead levels adjusted for the effects of the demographic covariates.

These adjusted natural logarithm blood lead levels were then

averaged by 6-month periods. Pearson correlation coefficients

were computed between these average natural logarithm blood

lead levels by 6-month periods and the total lead used in gasoline

per 6 months. This correlation varied slightly by whether the

6-month periods were chosen as January-June and JulyDecember or April-September and Octobe–March. Results

for both selections and for an average of the two were shown in

text table C for all races and for selected population subgroups

defined by race, sex, and age.

57
Table Xl 11. Results of regression of the natural logarithm of the blood lead Iavel on time and the demographic covariates: National Health and

Nutrition Examination Survey, 1976–80

Degrees Degrees

Race, sex, age, F of Rac(?, sex, age, F of

and variable statistic freedom Probability Coefficient and variable statistic freedom Probability Coefficient

All races

ORDER . . . . . . . . .

ORDERI . . . . . . . .

CHILD . . . . . . . . . .

TEEN. . . . . . . . . . .

RURAL . . . . . . . . .

INCH, . . . . . . . . . .

RACEI . . . . . . . . .

SOUTH . . . . . . . . .

ASI . . . . . . . . . . . .

SEX. . . . . . . . . . .

AS, . . . . . . . . . . .

AR C . . . . . . . . . . .

All . . . . . . . . . . . .

AID . . . . . . . . . . . .

RUB . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

Black

ORDER . . . . . . . . .

ORDER. . . . . . . .

CHILD . . . . . . . . . .

TEEN. . . . . . . . . . .

INCH . . . . . . . . . . .

WINTER . . . . . . . .

AS . . . . . . . . . . . .

SEX. . . . . . . . . . .

AS. . . . . . . . . . . .

All . . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

White

ORDER . . . . . . . . .

ORDER. . . . . . . .

CHILD . . . . . . . . . .

TEEN. . . . . . . . . . .

RURAL . . . . . . . . .

INCH . . . . . . . . . . .

SOUTH . . . . . . . . .

AS I . . . . . . . . . . . .

SEX. . . . . . . . . . .

All . . . . . . . . . . . .

AS. . . . . . . . . . . .

AID . . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

White, male

ORDER . . . . . . . . .

ORDERI . . . . . . . .

5.78

22,34

319.62

0.26

4.77

1.41

12.13

10,77

290.58

1,585.72

77.92

19.69

72.77

10.35

4.66

. . .

168.41

7.21

2.73

129.26

2.93

0.B8

10.61

42.69

132.84

27.65

13.05

. . .

40.41

5.12

21.37

230.72

0.05

5.25

2.26

12.36

207.86

1,195.37

53.B3

51.46

7.82

. . .

136.93

5.07

19.16

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

.,.

15

1

1

1

1

1

1

1

1

1

1

. . .

10

1

1

1

1

1

1

1

1

1

1

1

1

. . .

12

1

1

0.0222

0.0000

0.0000

0.6148

0.0364

0.2434

0.0015

0.0025

0.0000

0.0000

0.0000

0.0001

0.0000

0.0030

0.0385

. . .

0.0000

0.0114

0.1083

0.0000

0.0965

0.3555

0.0027

0.0000

0.0000

0.0000

0.0010

. . .

0.0000

0.0306

0.0001

0.0000

0.8224

0.0287

0.1424

0.0013

0.0000

0.0000

0.0000

0.0000

0.0087

. . .

0.0000

0.0314

0.0001

-0.00337

-0.01563

0.3543

0.0123

-0.0511

-0.0129

0.094B

-0.0701

-0.3336

0.3656

-0.1805

0.1110

-0.1611

-0.0835

0.0740

2.5933

. . .

-0.004519

-0.007368

0.5216

0.0548

-0.0298

-0.1141

+).4387

0.4176

-0.2514

-0.1314

2.6924

. .

-0.003467

-0.01612

0.332204

0.006612

-0.05389

-0.01652

-0.07817

-0.3215

0.3597

-0.1503

-0.1 7B7

-0.6685

2.6092

. . .

-0.003379

-0.01592

White, male—Con.

CHILD . . . . . . . . . .

TEEN . . . . . . . . . . .

INCH . . . . . . . . . . .

SOUTH . . . . . . . . .

All, . . . . . . . . . . .

AID . . . . . . . . . . . .

Intercept. . . . . . .

Overall ..,......

White, female

ORDER. . . . . . . . .

ORDERI. . . . . . . .

CHILD . . . . . . . . . .

TEEN. . . . . . . . . . .

RURAL . . . . . . . . .

INCH . . . . . . . . . . .

SOUTH . . . . . . . . .

All . . . . . . . . . . . .

AID . . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

White, 6 months5 years old

ORDER . . . . . . . . .

ORDIER1. . . . . . . .

INC1!. . . . . . . . . . .

SOUTH. . . . . . . . .

SEXI . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

VVhite, 6-17

years old

ORDER . . . . . . . . .

ORDER. . . . . . . .

SEX.l . . . . . . . . . . .

INCH . . . . . . . . . . .

Intercept. , . . . . . .

Overall . . . . . . . . .

White, 18-74

years old

ORDER . . . . . . . . .

ORDER. . . . . . . .

SE)(I . . . . . . . . . . .

RURAL . . . . . . . . .

SOILJTH. .

. . . . . . .

intercept. . . . . . . .

Ovwall . . . . . . . . .

2.04

22.48

6.71

13.06

10.37

3.06

. . .

39.17

4.61

17.80

161.33

0.08

7.16

0.48

10.25

32.13

6.49

. . .

46.67

8.82

8.45

73.76

3.66

4.46

,..

39.01

2.43

22.16

72.15

7.89

. . .

32.91

4.29

20.16

1,193.67

5.12

14.69

.,.

295.14

1

1

1

1

1

1

..

8

1

1

1

1

1

1

1

1

1

,..

9

1

1

1

1

1

. . .

5

1

1

1

1

. . .

4

1

1

1

1

1

. . .

6

0.1631

0.0000

0.0143

0.0010

0.0029

0.0897

. . .

0.0000

0.0395

0.0002

0.0000

0.7751

0.0117

0.4944

0.0031

0.0000

0.0158

. . .

0.0000

0.0056

0.0066

0.0000

0.0646

0.0426

. . .

0.0000

0.1288

0.0000

0.0000

0.0084

. . .

0.0000

0.0465

0.0001

0.0000

0.0306

0.0006

. . .

0.0000

-0.03030

-0.1740

-0.04BI

-0.0861

-0.0939

-0.0816

2.9524

. . .

-0.003724

-0.01655

0.36834

0.00761

-0.0729

0.0106

-0.0776

-0.2055

-0.0908

2.6137

. . .

-0.005682

-0.01325

-0.1 po2

-0.0670

0.0367

2.9341

. . .

-0.002974

-0.02028

-0.1797

-0.0889

2.S234

. . .

-0.003226

-0.01584

0.3588

-0,0525

-0,0882

2.5963

. . .

58
Table XIV. Percent decrease in blood lead levels over the survey

period, after accounting for tha effects of the demographic

covariates, by selected group characteristics: United States,

1976-80

Beginning

Group of the End of Percent

characteristic survey the survey Difference difference

Blood lead levels in micrograms per deciliter

All races . . . . . . . 14.59 9.17 5.42 37.1

Black . . . . . . . . . . 16.70 11.51 5.79 31.1

White . . . . . . . . . 14.38 8.91 5.46 38.0

Male . . . . . . . . 16.73 10.46 6.27 37.5

Female . . . . . . 12.51 7.59 4.92 39.3

0.5-5 years. . . 16.51 9.61 6.90 41.6

6-17 yeara. . . 12.82 7.56 5.27 41.1

18-74 years. . . 14.66 9.25 5.41 36.9

59
Tabla XV. Results of regression of the natural logarithm of the blood lead level on the gasoline lead variable and the demographic covariates:

United States, 1976-80

Degrees Degrees

Race, sax, age, F of Race, sex, age, F of

and variable statistic freedom Probability Coefficient and variable statistic freedom Probability Coe~icient

All races

GAS . . . . . . . . . .

CHILD . . . . . . . . . .

TEEN . . . . . . . . . . .

RURAL . . . . . . . . .

INCH . . . . . . . . . . .

RACE . . . . . . . . .

SOUTH . . . . . . . . .

AS . . . . . . . . . . . .

SEXI . . . . . . . . . . .

AS . . . . . . . . . . . .

ARI . . . . . . . . . . .

All . . . . . . . . . . . .

AID . . . . . . . . . . . .

RUB . . . . . . . . . . .

intercept. . . . . . . .

Overall . . . . . . . . .

Black

GAS . . . . . . . . . .

CHILD . . . . . . . . . .

TEEN . . . . . . . . . . .

INCH . . . . . . . . . . .

WINTER . . . . . . . .

AS . . . . . . . . . . . .

SEX . . . . . . . . . . .

AS . . . . . . . . . . . .

All . . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

White

GAS . . . . . . . . . .

CHILD . . . . . . . . . .

TEEN . . . . . . . . . . .

RURAL . . . . . . . . .

INCH . . . . . . . . . . .

SOUTH . . . . . . . . .

AS . . . . . . . . . . . .

SEXI . . . . . . . . . . .

AS . . . . . . . . . . . .

All . . . . . . . . . . . .

AIZ . . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

White, male

GAS . . . . . . . . . .

CHILD . . . . . . . . . .

96.31

287.93

0.19

20.20

2.05

5.96

0.84

289.11

1,495.38

82.36

24.69

65.95

10.31

5.69

. . .

174.53

42.28

174.48

2,56

2.93

6.32

53,77

136.37

25.24

11.91

. . .

62.96

94.50

229.73

0.02

22.32

2.79

0,53

224.67

1,119.97

52.62

57.11

7.86

,..

135.18

92.08

1.86

1

1

1

1

1

1

1

1

1

1

1

1

1

1

,..

14

1

1

1

1

1

1

1

1

1

. . .

9

1

1

1

1

1

1

1

1

1

1

1

. .

11

1

1

0.0000

0.0000

0.6657

0.0001

0.1618

0.0203

0.3663

0.0000

0.0000

0.0000

0.0000

0.0000

0.0030

0.0232

. . .

0.0000

0.0000

0.0000

0.1194

0.0968

0.0172

0.0000

0.0000

0.0000

0.0016

. . .

0.0000

0.0000

0.0000

0.8779

0.0000

0.1044

0.4713

0.0000

0.0000

0.0000

0.0000

0.0085

. . .

0.0000

0.0000

0.1818

1.5159

0.3597

0.0106

-0.1031

-0.0162

0.0714

0.0211

–0.3354

0.3668

–0.1 750

0.1174

-0.1684

–0.0844

0.0771

1.7999

. . .

1.1121

0.5298

0.0505

-0.048S

-0.0959

-0.4544

0.4223

-0.2391

-0.1252

2.0702

. . .

1.5944

0.3368

0.00453

-0.1082

-f.l.0192

0.0165

-0.3247

0.3606

-0.1740

-0.1574

-0.0875

1.7761

. . .

1.5675

-00288

White, male—Con.

TEEN . . . . . . . . . . .

INCH . . . . . . . . . . .

SO(JTH . . . . . . . . .

All, . . . . . . . . . . .

AID . . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

VVhite, female

GA!SQ . . . . . . . . . .

CHILD . . . . . . . . . .

TEEN . . . . . . . . . . .

RURAL . . . . . . . . .

INCH . . . . . . . . . . .

SOUTH . . . . . . . . .

All . . . . . . . . . . . .

AIZ . . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

White, 6 montha5 years old

GAS . . . . . . . . . .

INCH, . . . . . . . . . .

SOUTH . . . . . . . . .

SEXI . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

White, 6-17

yeara old

GAS . . . . . . . . . .

SEX . . . . . . . . . . .

INI:I . . . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

White, 18-74

yeara old

GAS . . . . . . . . . .

SEX . . . . . . . . . . .

RURAL . . . . . . . . .

SOUTH . . . . . . . . .

Intercept. . . . . . . .

Overall . . . . . . . . .

19.25

5.82

0.02

11.21

3.16

. . .

34.18

81.12

169.76

0.02

26.51

0.18

0.90

38.90

6.67

. . .

38.93

81.13

76.98

1.05

3.62

.,,

47.34

38.75

89.82

10,27

. . .

39.35

86.33

1,108.31

23.39

0.03

. . .

290.39

1

1

1

1

1

..

7

1

1

1

1

1

1

1

1

. .

8

1

1

1

1

. .

4

1

1

1

. .

3

1

1

1

1

. .

4

0.0001

0.0218

0.8997

0,0021

0.0848

. . .

0.0000

0.0000

0.0000

0.8888

0.0000

0.6724

0.3509

0.0000

0.0146

. . .

0.0000

0.0000

0.0000

0.3121

0.0661

. . .

0.0000

0.0000

0.0000

0.0031

. . .

0.0000

0.0000

0.0000

0.0000

0.8563

. . .

0.0000

-0.1676

-0.$)472

-0.00307

-o,i 039

-0.0872

2.0981

. . .

1.6721

0.3735

0.00374

-0!1337

0.00643

0.0237

+3,21 31

-r+0887

1;7415

.,.

1.7876

-0.1711

0.0314

().0334

1.9330

. . .

1.6086

0.1902

-0.1041

1.6978

. . .

1.5454

0.3602

-0.1037

0.00465

1.7880

. . .

60
Tabla XVI. Percent decreasa in blood Iaad Ievals over the survey

pariod that can ba axplainad by a dacline in the use of lead in

gasoline, after accounting for the effacts of the demographic

covariates by salectad group characteristic= United States,

1976-80

Beginning

Group of the End of Percent

characteristic survey the survey Difference difference

Blood lead levels in micrograms per deciliter

All races . . . . . . . 14.82 9.48 5.35 36.1

Black . . . . . . . . . . 16.24 11.70 4.54 28.0

White . . . . . . . . . 14.63 9.14 5.49 37.5

Male . . . . . . . . 17.04 10.73 6.31 37.0

Female . . . . . . 12.71 7.76 4.95 38.9

0.5-5 years. . . 16.40 9.68 6.72 41.0

6-17 years. ., 13.08 8.14 4.94 37.8

18-74 yaara... 14.95 9.48 5.47 36.6

61
Vital and Health Statistics

series descriptions

SERIES 1.

SERIES 2.

SERIES 3.

SERIES4.

SERIES 5.

SERIES 10.

SERIES1l.

;ERIES 12.

ERIES 13.

Programs and Collation Procedures-Reports describing

the general programs of the National Center for Health

Statistics and its offices and divisions and the data COI.

Iection methods used. They also include definitions and

other material necessary for understanding the data.

Data Evaluation ●nd Methods, Remarch-Studies of new

statistical methodology including experimental tests of

new suwey methods, studies of vital statistics collection

methods, new analytical techniques, objective evaluations

of reliability of collected data, and contributions to

statistical theory. Studies also include comparison of

U.S. methodology with those of other countries.

Analytical ●nd Epidamiological Studies-Reports preS8ntin9 analytical or interpretive studies based on vital

and health statistics, carrying the analysis further than

the expository types of reports in the other series.

Documonts ●nd Committaa Raporta- Final reports of

major committees concerned with vital and health statisti= and documents such as recommended mo&t vital

registration lam and revised birth and death certificates.

Comparative International Vital and Health Statistics

Reports-Analytical and descriptive reports comparing

U.S. vital and health statistics with those of other coun.

tries.

Data From the National Health I nterviaw Survey-Statistics on illness, accidental injuries, disability, use of hospital, medical, dental, and other services, and other

health-related topics, all based on data collected in the

continuing national household interview survey.

Data From the National Health Examination Survey and

the National Hodth ●nd Nutrition Examination SurveyData from direct examination, testing, and measurement

of national samples of the civilian noninstitutional ized

population provide the basis for (1) estimates of the

medically defined prevalence of specific diseases in the

United States and the distributions of the population

with r8$p8ct to physical, Physiological, and ~ycho.

logical characteristi~ and (2) analysis of relationships

among the various measurements without reference to

an explicit finite universe of parsons.

Data From the Institutimsalizad Population Surveys-Discontinued in 1975. Reports from these surveys are included in Series 13.

Data on Haalth Resour- Utilization-Statistics on the

utilization of health manpower and facilities providing

long-term care, ambulatory care, hospital care, and family

planning services.

SERIES 14.

SERIES 15.

SERIES 20.

SERIES 21.

SERIES 22.

SERIES 23.

Data on Health Rasourcas: Manpower and FacilitiaaStatistics on the numbers, geographic distribution, and

characteristics of health resources including physicians,

dentists, nurses, other health occupations, hospitals,

nursing homes, and outpatient facilities.

Data From Special Survays-Statistics on health and

health-related topics collected in special surveYs that

are not a part of the continuing data systems of the

National Center for Health Statistics.

Data on Mortality-Various statistics on mortalitv other

than as included in regular annual or monthly reports.

Special analyses by cause of death, age, and other demographic variables; geographic and time series analYses;

and statistics on characteristics of deaths not available

from the vital records based on sample surveys of those

records.

Dats on Natality, Marriaga. and Divorce-Various statistics on natality, marriage, and divorm other than as

included in regular annual or monthly reports. Special

anal ysas by damograph ic variables; geographic and time

series analyses; studies of fertility; and statistics on

characteristics of births not available from the vital

records based on sample surveys of th me records.

Data From the National Mortality and Natality SurveysDiscontinued in 1975. Reports from these sample surveys

based on vital records are included in series 20 and 21,

rmpectively.

Data From the National Survey of Family GrowthStatistics on fertility, family formation and dissolution,

family planning, and related maternal and infant health

topics derived from a periodic survey of a nationwide

probability sample of ever-married wornan 1544 years

of age.

For a list of titles of reports published in these series, write to:

or call

Scientific and Technical Information Branch

National Center for Health Statistics

Public Health Service

Hyattsville, Md. 20782

301-436-NCHS
U.S. DEPARTMENT OF HEALTH AND

HUMAN SERVICES

Public Health Service

National Center for Health Statistics

3700 East-West Highway

Hyattaville, Maryland 20782

OFFICIAL 8USINESS

PENALTY FOR PRIVATE USE, $300

I I

DHHS Publication No. (PHS) 84–1 683, Series 11, No. 233