Blood Lead Levels for Persons 6 Months-74 Years of Age: 

United States, 1976-80 

by Joseph L. Annest, Ph. D., Division of Health Examination Statistics; Kathryn R. Mahaffey, Ph. D., Food and Drug Administration, Cincinnati, Ohio; Dennis H. Cox, Ph. D., Centers for Disease Control, Atlanta; and Jean Roberts, M. S., Division of Health 

@ 

@ 

Examination Statistics 

Introduction 

One of the more recent growing public health 

concerns is the impact of the changing environment 

on health.1 As a part of this concern, the Division of 

Health Examination Statistics of the National Center 

for Health Statistics has measured the degree of exposure of the U.S. civilian noninstitutionalized popution to certain toxic substances, including lead. This 

as accomplished by determining blood lead concentrations, a common index of lead exposure, on examinees from the second National Health and Nutrition 

Examination Survey (NHANES II). The rationale for 

measuring exposure to this environmental hazard was 

to (1) provide information for the first time about 

the distribution of blood lead levels in the general 

U.S. population, (2) establish baseline estimates for 

future studies to monitor changes in such exposure 

over time, (3) provide normative information for use 

in health policy and regulatory decisions, and (4) 

correlate levels of exposure to these toxic substances 

with other health and nutritional parameters measured on examinees in NHANES 11.~ 

Surveillance data, from the Centers for Disease 

Control (CDC) on childhood lead poisoning in the 

United States gives some indication of the extent to 

which lead exposure is a public health problem 

among children. A recent Centers for Disease Control 

Morbidity and Mortality Weekly Reports states that 

for the first 6 months of fiscal year 1981, almost 

20,000 children were known to be under pediatric 

management for lead toxicity. These CDC surveillance data come from approximately 60 federally 

funded screening projects located in about 25 States. 

azards of industrial exposure to lead are well 

ocumented, but the actual magnitude and significance of general community exposure to lead in the 

environment has been a controversial subject for 

years.h 

This report presents statistics on the distribution 

of blood lead levels of persons ages 6 months-74 years 

in the United States with respect to age, race, sex, 

annua~ famiIy income, and degree of urbanization (of 

place of residence). These are the fiist national estimates of lead levels in whole blood obtained on a representative sample of the U.S. population. A future 

NCHS Series 11 publications is planned to provide 

detailed descriptive statistics for blood lead levels for 

selected demographic, socioeconomic, health, and 

nutritional factors. 

NHANES II survey sample design 

A brief description of the sample design of 

NHANES II is presented in the Technical Notes. A 

detailed description of the survey design has been 

published.~ 

From a total of 27,801 NHANES II sample persons, 16,563 persons were asked to provide blood 

specimens for use in the assessment of blood lead 

levels. These included all children ages 6 months6 years and a half-sample (those assigned odd sample 

numbers for the examination) of persons ages 7-74 

years. However, some parents refused to have their 

young children examined and/or give blood. Some 

adults, especially the elderly, were reluctant or unable 

to come to the mobile examination units (set up at 

centralized locations within the 64 sampling areas) 

for examination. Also, to a lesser degree, a number of 

blood specimens were lost during shipment and processing. As a result, reliable blood lead levels were determined for blood specimens from 10,049 exarninees. Capillary blood was obtained from 113 children 

ages 6 months-7 years by fingerstick, and venous 

blood from the remaining 9,936 examinees by venipuncture. 

To estimate the potential bias of missing data, the 

distribution of sample persons in the lead subsample 

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES, Public Health Service, Office of Health Research, Statistics, and Technology 
2 

with missing blood lead data was investigated with 

respect to the relevant demographic variables. The 

results suggest that sample persons with missing blood 

lead data are distributed randomly by race, sex, 

income, and degree of urbanization. However, some 

caution should be exercised in using these findings because of the high percent of missing data. Approximately 40’ percent of the 16,563 sample persons had 

no blood lead determinations. Details (tables I and H) 

on nonresponse are presented in the Technical Notes. 

Further investigation of potential bias due to nonresponse with respect to demographic variables and related medical history components is planned for the 

Series 11 report in preparation.5 

In this report, statistics are presented for three 

age categories to ensure subsamples of sufficient size 

for reliable national estimates–preschool children 

ages 6 months-5 years, youths ages 6-17 years, and 

adults ages 18-74 years. 

It should be noted that the mean blood lead levels 

and the proportion of children with elevated bl 

lead levels presented in this study would be expe 

m to differ from those obtained from the communitybased lead poisoning prevention programs directed by 

the CDC. The CDC program is designed to screen selectively or on request for individuals at potentially 

high risk of exposure to lead using initially an erythrocyte protoporphorin (EP) test followed by blood 

lead tests on those with EP levels of 50 micrograms 

per deciliter (pg/dl) of whole blood or more.6 On the 

other hand, the NHANES II utilizes a probability 

sample representative of the general U.S. population 

selecting individuals for examination and blood lead 

determinations independent of their risk of exposure 

to lead or their EP test results. 
ammdata3 

“Wethods and procedures 

The laboratory determinations of blood lead 

levels for this national survey were performed by the 

Clinical Chemistry Division, Center for Environmental Health, Centers for Disease Control (CDC), 

Atlanta. Georgia, and financed by the Division of 

Nutrition. Bureau of Foods, FDA, Cincinnati, Ohio. 

Descriptions of the materials, methods, and quality 

control procedures are presented elsewhere. T~8 Lead 

concentrations of NHANES 11 whole blood specimens 

and control specimens were determined by atomic 

absorption spectrophotometry using a modified 

Delves cup micromethoci.g Specimens were analyzed 

in duplicate with the two assessments done independently in the same analytic run. The average of the two 

measures was used in the analysis presented in this 

report. 

The following national estimates are based on 

data obtained on 9,933 NHANES 11 examinees with 

blood lead levels ranging from 2.0-66.0 #g/all of 

whole blood among those who received venipunctures. Although the fingertips were carefully prepared 

to minimize contamination, potential for contamina­

,+-’--­

tion during the capillary blood collection by fingerstick (pricking the finger) is recognized.l 0 Statistical 

analysis of the unweighed data suggested that inclusion of the fingerstick data in this analysis would have 

introduced bias to the estimates of mean venous 

blood lead levels in children. Overall, for children ages 

6 months-5 years, unweighed mean blood lead level 

for those receiving fingersticks was observed to be 

approximately 6.0 pg/dl higher than for those receiving venipunctures. This observed mean difference was 

consistent for black and white people. The three examinees with venipunctures showing blood lead levels 

greater than 70.0 Lg/dl are extreme cases of lead exposure. These have been considered a separate part of 

the distribution of blood lead levels in the general 

population. Therefore, the fingerstick data and values 

for the three extreme venipuncture cases were excluded from detailed tables 1-7 and further stages of 

the analysis. A description (table 111) of blood lead 

levels for 113 children ages 6 months-7 years receiving fingersticks and of the three extreme cases of lead 

exposure is given in the Technical Notes. 

,------
4 

Findings 

Mean blood lead levels by age, 

race, and sex 

Mean blood lead level estimates for the U.S. 

population differ substantially with respect to age, 

race, and sex (figures 1-3 and tables 1-3). 

For young children ages 6 months-5 years, mean 

blood lead levels are similar among those of the same 

age and sex (figure 1). The differences between means 

among age and sex groups shown in figure 1 are not 

statistically significant at the 0.05 level. However, 

mean blood lead levels of black children significantly 

exceed those of white children. Overall for this age, 

blood lead levels among black children are, on the 

average, 6.0 pg/dl higher than among white children. 

Overall for children and youths ages 6-17 years, 

there is a significant decreasing trend in mean blood 

Males 

24 

20 ~ 

& 

~ 16 m 

n

0. 

c 12 

~ 

2 8 

0 

6 months-2 years 3-5 years 

Females 

24r -1-

6 months-2 years 3-5 years 

SOURCE: National Health and Nutrition Examination 

Survey, National Center for Health Statistics. 

Figure 1. Mean blood lead levels (PbB) of children ages 6 months5 years: United States, 1976-80 

T 

lead levels with increasing age. Eliminating the effect 

of age, significant race and sex differences are 

evident. Generally, as age increases the difference in 

mean blood lead levels between boys and girls progressively increases. There is a significant inverse relationship of blood lead level with age for black persons; that is, mean blood lead levels decrease as age 

(successive age groups) increases through the age of 

17 years. The relationship between blood lead level 

and age for white children and youths is similar to 

that for the respective black groups, except that mean 

blood lead levels decline with increasing age until 

about age 15 (or the 15-17-year age group) where the 

mean blood lead levels are observed to be higher 

(figure 2). 

For adults ages 18-74 years, the sex difference in 

blood lead levels is pronounced and significant. The 

mean blood lead levels of men are consistently higher 

than those of women in all age groups. The differences in these levels between the sexes are similar for 

+ 

I 95-percent confidence 

intervals ~

White persons 

24 r 

6-8 years 9-11 years 12-14 years 15-17 years 

Black persons 

24 ~ 

1-1-

6-8 years 9-11 years 12-14 years 15-17 Years ~ 

SOURCE: National Health and Nutrition Examination 

Survey, National Center for Health Statistics. 

Figure 2. Mean blood lead levels {PbB) of youths ages 6-17 years: 

United States, 1976-80 

I 
dmcedab5 

) ~ Male 

= ~e!,,e 

I 95-percent confidence 

intervals 

White persons 

28 

24 

~ 

20 % 

~


2 16
 L


c


12 : 

8 

0 

18-24 25-34 35-44 45-54 55-64 65-74 

years years years years years years 

Black persons 

28 

24 [ -r T 

18-24 25-34 35-44 45-54 55-64 65-74 

years years years years years years 

SOURCE: National Health and Nutrition Examination 

Survey, National Center for Health Statistics. 

Figure 3. Mean blood lead levels (PbB) of adults ages 18-74 years: 

United States, 1976-80 

white and for black persons (figure 3). In addition, 

there is a significant relationship between mean blood 

lead level and age. However, the trend in mean blood 

lead levels with age differs for white and for black 

men. For instance, when the mean blood lead levels 

for white and black men are compared, those for 

white men increase with age until age group 35-44 

years and then decrease while those for black men remain high through age group 55-64 years. After accounting for differences in the age distributions for 

both races, there are significantly higher mean blood 

lead levels among black than among white adults. 

alood lead levels for children by income 

d degree of urbanization 

The associations of family income and of the degree of urbanization with blood lead levels are generally consistent across all three broad age groups in the 

population with lower mean blood lead levels among 

the more affluent than among the poor and those in 

rural than in urban areas (tables 4 and 5). These associations were most pronounced, however, in children 

ages 6 months-5 years. Hence, further consideration 

of blood lead levels in this report with respect to 

these demographic variables will be limited to the 

findings among preschool-aged children. 

The most common sources of environmental lead 

fou young children are air, food, dust, dirt, soil, water, 

and lead-b~sed paint. Lead usually enters the body by 

ingestion or inhalation. In very young children, clinical studies have shown that approximately 40 percent 

of the lead ingested is absorbed from the gastrointestinal tract, while adults absorb about 5 to 10 percent of ingested lead. 

The 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 studiesl 2 suggest that, in general, 

20 to 40 percent of the inhaled lead will be deposited 

in the respiratory tract. However, because of higher 

metabolic rates and greater physical activity of children, it is estimated 3 that under comparable exposure, children inhale two to three times as much 

airborne lead per unit of body weight as adults do. 

Even at relatively low levels of lead, subclinical 

effects of lead exposure in children, including impaired hematopoiesis and neuropsychologic deficits, 

have been reported in the literature.14J 15 

In each of the three income groups, the mean 

blood lead levels of black children are significantly 

greater than those of white children (figure 4). The 

smallest race difference is in the highest income 

group. There is also a significant inverse relationship 

between mean blood lead level and income. For this 

analysis, three income categories were selected to ensure subsamples of adequate size for computing these 

national estimates. In 1978, the income level of 

$6,000 was near the poverty threshold for a family 

of four as determined by the U.S. Bureau of the 

Census.16 

Mean blood lead levels are observed to be higher 

in the urban areas than in the rural areas for white 

and black children with statistically significant differences only for the white group (figure 5). Also, mean 

blood lead levels for black children are significantly 

higher than those for white children within all three 

urban-rural groups. This consistent mean difference 

between black and white children indicates that the 

observed racial effects are not simply explained by 

the degree of urbanization. No clearcut explanation 

can be given from the results of this study; however, 

these results are consistent with the findings of other 

studies regarding this racial difference.1 7-19 

Further investigation of those living in the large 

urban areas ( 1 million or more people) (figure 6 and 

table 6) revealed that mean blood lead levels of black 

I 
6 

Table 1. Blood lead levels of persons 6 months-74 years, with mean, standard error of the mean, median, and percent distribution, by race and age: ‘ 

United States, 1976-80 

Estimated Blood lead level (pg/dl) 

population Number 

Race and age in examined2 Standard Less 

rhousan ds 1 Mean error of Median than 10-19 20-29 30-39 40-49 50-59 60-69 

the mean 10 

All races3 Percent distribution 

Alleges . . . . . . . . . . . 203,554 9,933 13.9 0.24 13.0 22.1 62.9 13.0 1.6 0.2 0,1 0.0 

6months-5 years . . . . . 16,862 2,372 16.0 0.42 15.0 12.2 63.3 20.5 3.5 0.3 0.1 0.0 

6-17 years . . . . . . . . . 44,964 1,720 12.5 0.30 12.0 27.6 64.8 7.1 0.5 

18-74 years . . . . . . . . 141,728 5,841 14.2 0.25 13.0 21.2 62.3 14.3 1.8 * 0.3 0.1 0.0 

White 

Alleges . . . . . . . . . . . 174,528 8,369 13.7 0,24 13.0 23.3 62.8 12.2 1.5 0.2 0.1 0.0 

6 months-5 years . . . . 13,641 1,876 14.9 0.43 14.0 14.5 67.5 16.1 1.8 0.1 0.1 0.0 

6-17years . . . . . . . . . 37,530 1,424 12.1 0.30 11.0 30.4 63.4 5.8 0.4 

18-74 years . . . . . . . . 123,357 5,069 14.1 0.25 13.0 21.9 62.3 13.7 1.8 0.3 0.1 0.0 

81ack 

All ages . . . . . . . . . . . 23,853 1,332 15.7 0.48 15.0 13.3 63.7 20.0 2.3 0.3 0.2 0.1 

6 months-5 years . . . . 2,584 419 20.9 0.61 20.0 2.5 45.4 39.9 10.2 1.4 0.5 0.1 

6-17years . . ...’.... 6,529 263 14,8 0.53 14.0 12.8 70.9 15.6 0.7 

18-74 years . . . . . . . . . 14,740 650 15.5 0.54 14.0 14.7 62.9 19.6 2.0 0.4 0.3 0.2 

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

Zwith lead determinations from blood specimens drawn by venipuncture, 

Slncludes data for races not shown sePWatelY. 

4Numbers may not add to totals due to rounding. 

o 

Table 2. Blood lead levels of males 6 months-74 years, with mean, standard error of the mean, median, and percent distribution, by race and age: 

United States. 1976-80 

Estimated Blood lead level (pg/dl) 

population Number , 

Race and age in examinedz Standard Less 

Mean error of Median than 10-19 20-29 30-39 40-49 50-59 60-69 thousandsl 

the mean 10 

All races3 Percent distribution 

. . 

Alleges . . . . . . . . . . . 99,062 4,945 16.1 0.26 15.0 10.4 65.4 20.8 2.8 0.3 0,1 0.1 

6 months-5 years . . . . . 8,621 1,247 16.3 0.46 15.0 11.0 63.5 21.2 4.0 0.3 0.0 0.0 

6-17 years . . . . . . . . . 22,887 902 13.6 0.32 13.0 19.1 70.1 10.2 0.7 - - -

18-74 years . . . . . . . . 67.555 2.796 16.8 0.28 16.0 7.6 64.1 24.2 3.4 0.4 0.1 0.1 

White 

Alleges . . . . . . . . . . . 85,112 4,153 15.8 0.27 15.0 11.3 66.0 19.6 2.6 0.3 0.1 0.0 

6 months-5 years . . . . . 6,910 969 15.2 0.46 14.0 13.0 67.6 17,3 2.0 0.1 - -

6-17years . . . . . . . . . 19,060 753 13.1 0.33 13.0 21.4 69.5 8.4 0.7 - . . 

lB-74 years . . . . . . . . 59,142 2,431 16.6 0.29 16.0 8.1 64.8 23.3 3.3 0.4 0.1 0.1 

81ack 

Alleges . . . . . . . . . . . 11,171 664 18.3 0.52 17.0 4.0 59.6 31.0 4.1 0.7 0.4 0.2 

6 months-5 years . . . . . 1307 231 20.7 0.74 19.0 2.7 48.8 35.1 11.1 1.9 0.2 ().3 

6-17years . . . . . . . . . 3,272 129 16.0 0.62 15.0 8.0 69.9 21.1 1.0 - -

18-74 years . . . . . . . . 6,592 304 19.1 0.70 18.0 2.3 56.4 34.9 4.5 0.8 0.6 0:4 

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


2With lead determinations fr~m bl~~d $pecimen$ drawn by venipun~ture.


Slncludes data for races not shown separately. 

4Number~ may not add to totals due to rounding. 
Table 3. Blood lead levels of females 6 months-74 years, with mean, standard error of the mean, median, and percant distribution, by ram and age: 

A United States, 1976-80 

Estimated Blood Iced level {N/all) 

population Number 

Race and age Standard in examinec# 

Mean error of Median thousands 1 the mean 

All racas3 

Alleges . . . . . . . . . . . 104,492 4,988 11.9 0.23 11.0 

6 months-5 yaars . . . . . 8,241 1,125 15.8 0.42 15.0 

&17yaars . . . . . . . . . 22,077 818 11.4 0.32 11.0 

lB-74years . . . . . . . . 74,173 3,045 11.8 0.22 11,0 

White 

All ages . . . . . . . . . . . 89,417 4,216 11.7 0.23 1.0 

6 months-5 years . . . . . 6,732 907 14.7 0.44 4.0 

6-17years . . . . . . . . . 18,470 671 11.0 0.31 1.0 

18-74 years . . . . . . . . 64,215 2,638 11.7 0.23 1.0 

81ack 

All ages . . . . . . . . . . . 12,6B2 668 13.4 0.45 3.0 

6 months-5 years . . . . . 1,277 166 21.0 0.69 20.0 

6-17years . . . . . . . . . 3,256 134 13.6 0.64 13.0 

lB-74years . . . . . . . . 8,148 346 12.7 0.44 12.0 

Less 

than 

10 

33.3


13.5


36.6


33.7


34.8


16.1


40.0


34.6


21.5


2.2


17.7


24.7


1At the midpoint of the survey, Merch 1, 1978. 

2Witi lead determinations from blood specimens drewn by veniPunCtUre. 

Slncludes de~ for re~es not shown ~perately, 

4Numbers mey not edd to tota(s due to r~”nding, 

~ White 

I 95-percent confidence 

intervals 

28 r
 24 L- 1-

Less than $6,000- $15,000 

$6,000 14,999 or more 

SOURCE: National Health and Nutrition Examination 

Survey, National Center for Health Statistics. 

Figure 4. Mean blood lead levels (Pb8) of children ages 6 months5 years by annual family income: United States, 1976-80 

.6----’. 

li)19 20-29 30-39 40-49 50-59 60-69 

Percent distribution 

60.5 5.7 0.4 0.1 0.1 -

63.2 19.8 3.0 0.3 0.2 -

59.3 3.9 0.2 - - -

60.6 5.2 0.3 0.1 0.1 -

59.6 5.0 0.4 0. 0.1 -

67.3 14.8 1.6 0. 0.1 -

56.9 2.9 0.2 -

59.9 5.0 0.4 0. 0.1 -

67.3 10.3 0.7 0. 0.0 -

41.6 45.3 9.2 0.9 0.8 -

71.9 10.0 0.4 - - -

68.1 7.2 - - - -

~ White 

~ 8,a~k 

I 95-percent confidence 

intervals 

-r 1-

Urban Urban Rural 

1,000,000 Fewer than 

persons 1,000,000 

or more persons 

24 r 

SOURCE: National Health and Nutrition Examination 

Survey, National Center for Health Statistics. 

Figure 5. Mean blood lead levels (pbB) of children ages 6 months5 years by degree of urbanization: United States, 1976-80 

b 
8 

Table 4, Blood lead levels of persons 6 months-74 years, with mean, standard error Of the mean, and selected percentiles, by annual family income, 

race, and age: Umted States, 1976-80 

P 

Annual family income 

Under $6,000 

Standard Percentile 

Race and age Estimated 

population Number 

in examined2 

thousandsl 

29,410 

2,465 448 

5,046 230 

21,898 ,184 

21,542 ,315 

1,408 256 

3,067 140 

17,067 919 

7,355 512 

917 176 

1,927 87 

4,512 249 — 

lAt the mjdpointof thesurvev, March 1, 1978. 

Zwith lead determinations from blood specimans drawn by Venl Puncture. 

Sln’ludes data for racas not shown separately. 

error Mean of the 

10th 50th mean 

Blood lead level (#g/all) 

14.5 0.40 8.0 

20.0 0.56 11.0 

14,6 0,61 8.0 

14.1 0.38 7.0 

14.0 0.44 7.0 

18,1 0.61 11,0 

14.0 0.69 8.0 

13.7 0.43 7,0 

15.8 0.47 9.0 

22,9 0.89 14.0 

15.7 0.76 10,0 

15.0 0.53 8.0 

13.0 

19,0 

13,0 

13,0 

12.0 

17.0 

13.0 

12,0 

15,0 

21.0 

15.0 

14.0 

90th 

23.0 

31.0 

22.0 

23.0 

23.0 

26.0 

22.0 

22.0 

24.0 

34.0 

22.0 

23.0 
admce@a9 

Table 4. Blood lead levels of persons 6 months-74 years, with mean, standard error of the mean, and selected percentiles, by annual family income, 

race, and age: United States, 1976-80—Con. 

Annual family income 

$6,000-14,999 .$75,000 or more 

Estimated Standard Percentile Estimated Standard Percentile 

population Number Mean error population Number Mean error 

in examined2 of the in examined2 of the 

thousandsl mean 10th 50th 90th thousandsl mean 10th 50th 90th 

Blood lead level (#g/all) 8iood lead level (pg/dl) 

80,416 4,033 14.2 0.25 8.0 13.0 22.0 87,062 3,718 13.5 0.24 8.0 13.0 20.0 

7,534 1,083 16.2 0.46 9.0 15.0 24.0 6,428 774 14.1 0.41 8.0 13.0 21.0 

17,533 672 12.9 0.41 7.0 12.0 19.0 20,874 761 11.7 0.25 7.0 11.0 17.0 

55,349 2,278 14.4 0.26 8.0 13.0 22.0 59,820 2,183 14.1 0.27 8.0 13.0 21.0 

68,135 3,413 13.9 0.26 8.0 13,0 21.0 79,707 3,407 13.4 0.26 8.0 13.0 20.0 

6,252 887 15.3 0.48 9.0 14.0 22.0 5,707 690 13.7 0.44 8.0 13.0 20.0 

13,936 531 12.4 0.39 7,0 12.0 18.0 19,174 705 11.6 0.28 7.0 11.0 16.0 

47,946 1,995 14,2 0.26 8.0 13.0 22.0 54,826 2,006 14.0 0.28 8.0 13.0 21.0 

10,334 533 16.1 0.48 9.0 15.0 24.0 4,995 224 14.9 0.58 9.0 14.0 22.0 

1,037 163 20.7 0.64 13.0 20.0 30.0 502 60 17.2 0.83 11.0 16.0 24.0 

3,159 125 14.9 0.71 10,0 14.0 21.0 1,225 42 13.6 0.79 7.0 13.0 20.0 

6,137 245 16.2 0.60 9.0 15.0 24.0 3,267 122 15.1 0.65 9.0 14.0 22.0 
10 advancedata 

Table 5. Blood lead levels of persons 6 months-74 years, with mean, standard error of the mean, and selected percentiles, by degree of urbanization 

race, and age: United States, 1976-80 

Degree of urbanization 

Urban, 1 million persons or more 

Race and age Estimated Standard Percentile 

population Number Mean error 

in examined2 of the 

thousands mean 10th 50th 90th 

All races Blood lead level (#g/all) 

All ages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59,532 2,395 15.0 0.37 9.0 14.0 22.0 

6 months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . 4,344 544 18.0 0.53 10.0 17.0 27.0 

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12,893 414 13.8 0.53 9.0 13.0 20.0 

18-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42,295 1,437 15.2 0.39 9.0 14.0 23.0 

White 

All ages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46,407 1,767 15.0 0.31 9.0 14.0 22.0 

6 months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,112 358 16.6 0.59 10.0 16.0 24.0 

6-17 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9,681 294 13.3 0.55 9.0 12.0 20.0 

18-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . 33,615 1,115 15.3 0.31 9.0 14.0 23.0 

Black 

All ages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11,687 570 15.5 0.84 9.0 14.0 23.0 

6 months-5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,093 172 22.2 0.83 14.0 20.0 35.0 

6-17years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,010 111 15.3 0.83 10.0 15.0 22.0 

18-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,585 287 15.0 0.89 8.0 14.0 22.0 

lAtthe midpoint of the survey, March 1, 1978. 

Zwith jeaddeterm i”ati~n~fr~m bl~~cj~p~~i~~n$dr~w” by”enipu”kt”re.


Slncludes data for races notshown separately. 

* 
akmedak 11 

Table5. Blood lead levalsof persons 6months-74 years, with mean, standard error of themean, andselected percentiles, by degree of urbanization, 

race, and age: United States, 1976-80 –Con. 

Degree of urbanization 

Urban, fewer than lmillionpe~ons Rural 

Estimated Standard Percentile Estimated Standard Percentile 

population 

in 

Ns)mber 

examinedz 

Mean error 

of the 

population 

in 

Number 

examinedz 

Mean error 

of the 

thousands mean 10th 50th 90th thousandsl mean 10th 50th 90th 

Blood lead level (#g/all) Blood lead level (#g/dI) 

79,906 3,869 13.9 0.32 8.0 13.0 21.0 64,116 3,669 13.0 0.40 7.0 12.0 20.0 

6,891 944 16.5 0.67 9.0 16.0 24.0 5,627 884 13.9 0.64 8.0 13.0 20.0 

16,988 638 12.6 0.35 7.0 12.0 19.0 15,083 668 11.4 0.52 7.0 11.0 16.0 

56,027 2,287 14.1 0.33 8.0 13.0 22.0 43,405 2,117 13.4 0.38 7.0 12.0 21.0 

67,707 3,144 13.6 0.32 8.0 13.0 21.0 60,414 3,458 12.8 0.39 7.0 12.0 20.0 

5,297 699 15.4 0.67 9.0 15.0 23.0 5,233 819 13.5 0.57 8.0 13.0 19.0 

13,871 510 12.2 0.36 7.0 11.0 18.0 13,978 620 11.2 0.48 7.0 11.0 16.0 

48,540 1,935 13.8 0.32 8.0 13.0 21.0 41,203 2,019 13.3 0.38 7.0 12.0 21.0 

9,783 612 15.9 0.54 9.0 15.0 24.0 2,383 150 16.2 0.68 9.0 14.0 25.0 

1,246 205 20.3 0.78 12.0 20.0 39,9 245 42 18.3 2.60 11.0 16.0 32.0 

2,717 113 14.5 0.64 B.O 14.0 20.0 802 39 13.9 1.33 8.0 13.0 20.0 

5,820 294 15.9 0.70 9.0 15.0 24.0 1,336 69 17.0 0.88 9.0 15.9 26.0 

. 
12 advancedata


and the presence of higher blood lead levels amen 

74 L T 

Central city Non-central city 

SOURCE: National Health and Nutrition Examination 

Survey, National Center for Health Statistics. 1 

Figure 6. Maan blood lead levels (PbB) of children ages 6 months5 years in large urban areas: Unitad States, 1976-80 

children in the central cities were observed to be 

higher than those of black children living in the noncentral cities and rural areas, respectively. These differences were neither statistically significant nor reliable because of the small number of black children in 

the sample. However, within the central cities, the 

mean blood lead level of black children was significantly higher than that of white children. Other 

studies indicate thatls exposure to lead in central 

city children may be associated, to some degree, with 

socioeconomic factors. It was observed ii this study 

that 43 percent of black compared with 22 percent of 

white children living in the central city areas were 

from households with annual family incomes of 

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

interview. 

The literatures suggests that preschool-aged chil­

‘	 dren from low income households living in the inner 

cities (the “urban lead-belt”) are at higher risk of exposure to environmental sources contaminated with 

lead than the general child population. Attempts to 

include such cross-classifications using the NHANES 

II data resulted in group sizes too small to be reliable 

estimators for the general population. For example, 

while it would have been of interest to determine if 

the association between race and blood lead level 

differed between various degrees of urbanization by 

income groups, the number of examinees within such 

groups was too small. 

Elevated blood lead levels in children 

The consistent difference in blood lead levels between black and white children ages 6 months-5 years 

those in the low income group and large urban ar 

can also be distinguished by looking at the percent o children with blood lead levels of 30 ~g/dl or more. 

According to CDC guidelines published in 1978:30 

Ng/dl is the cutoff used in the CDC community-based 

lead poisoning prevention programs for referring children for followup. 

Based on the CDC guidelines (30.0 ~g/dl or 

more), NHANES II data indicate than an estimated 

4.0 percent or approximately 675,000 U.S. children 

6 months-5 years of age have elevated blood lead 

levels (table 7). Among children of this age, 12.2 percent of black children compared to 2.0 percent of 

white children had blood lead levels of 30 pg/dl or 

more. This difference is significant for boys and for 

girls. The percent with elevated blood lead levels are 

observed to be slightly higher in boys than girls, but 

this difference is not statistically significant at the 

0.05 level of probability. 

There was a significant decrease in the proportion 

of children with elevated blood lead levels with increased family income. This relationship was stronger 

for black than 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 perso 

with elevated blood lead levels was lowest in the h 

income group. e 

With respect to degree of urbanization, the percent with elevated blood lead levels living in the central cities was significantly higher for black than 

white children. Even in the smaller urban and rural 

areas, 10.0 percent of black children were 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 a relatively small number of examined persons (42 cases) in the estimation cell for rural 

black children. 

Trends in lead levels 

Preliminary analyqes suggest that in the 4-year 

period of this survey there was a 37-percent decrease 

in the mean blood lead levels from 15.8 pg/dl during 

the first 6 months of the survey to 10.0 pg/dl during 

the last 6 months (figure 7). 

Decreases were found for both black and white 

races, all age groups, and both sexes (figure 8). 

Further analysis indicated. that the decline was not 

due to seasonal, income, geographic region, or urbanrural differences. Nor was it due to laboratory me 

urement error or chance.zo 

o 
Ta Iood lead Iavals of persons 6 months-74 yaars, with mean. standard error of the and selected percentiles, by large urban areas, race, and age: Unitad States, 1976-

Large urban areas 

Central city Non-central city 

Race and age Estimated Standard Percentile Estimated Standard Percentile 

population Number 

in examinedz 

Mean error 

of the 

population Number Mean error 

in examined2 of the 

thousands mean 10th 5oth 90th thousands~ mean 10th 50th 90th 

All races3 Blood lead level (pg/dl) 8100d lead level (pg/dl) 

Alleges . . . . . . . . . . . . . . . . . . . . . . . . . . 24,560 1,123 14.9 0.67 9.0 14.0 22.0 34,908 1,268 15.1 0.30 9.0 14.0 23.0 

6months-5years . . . . . . . . . . . . . . . . . . . . 1,822 286 20.0 0.71 11.0 19.0 31.0 2,519 257 16.5 0.60 10.0 16.0 24.0 

f+17years . . . . . . . . . . . . . . . . . . . . . . . . 5,124 177 14.6 0.87 9.0 14.0 21.0 7,746 236 13.3 0.59 9.0 12.0 19.0 

18-74years . . . . . . . . . . . . . . . . . . . . . . . . 17,614 660 14.7 0.70 8.o 14.0 22.0 24,643 775 15.6 0.29 9.0 14.0 23.0 

White 

Alleges . . . . . . . . . . . . . . . . . . . . . . . . . . 14,602 625 14.8 0.56 9.0 14.0 22.0 31,741 1,138 15.1 0.32 9.0 14.0 23.0 

6months-5yaars . . . . . . . . . . . . . . . . . . . . 885 133 17.4 0.84 10.0 17.0 25.0 2,223 224 16.2 0.65 10.0 15.0 24.0 

6-17years . . . . . . . . . . . . . . . . . . . . . . . . 2,710 86 14.3 0.93 9.0 14.0 21.0 6,949 207 13.0 0.63 8.0 12.0 18.0 

18-74years . . . . . . . . . . . . . . . . . . . . . . . . 11,007 406 14.8 0.59 9.0 14.0 22.0 22,569 707 15.6 0.30 9.0 14.0 23.0 

Black 

All eges . . . . . . . . . . . . . . . . . . . . . . . . . . 8,856 452 15.4 0.94 8.0 14.0 23.0 2,831 118 16.0 0.60 9.0 15.0 22.0 

6months-5years . . . . . . . . . . . . . . . . . . . . 855 143 23.1 1.30 14.0 21.0 36.0 238 29 19.2 0.74 14.0 19.0 26.0 

6-17years . . . . . . . . . . . . . . . . . . . . . . . . 2,259 84 15.0 1.00 9.0 14.0 21.0 751 27 16.0 0.67 10.0 16.0 22.0 

18-74years . . . . . . . . . . . . . . . . . . . . . . . . 5,742 225 14.8 0.95 8.0 14.!3 22.0 1,842 62 15.7 0.80 9.0 15.0 22.0 

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

Zwith lead determinations from blood specimens drawn by VeniPUnCtUre. 

s]n~lude~ da- for ra~e~ not shown ~aparataly. .. 
14 aduancedata


Table7. Percent ofchildmn ages6months-5 years with blood lead levels of30.0#g/dl ormore,l with standard error of thepercent, by selected 

demographic variables: United States, 1976-80 

All All Demographic variable White Black White Black racesz races2 

Percent of children’,3 Standard error 

8oth sexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.0 2.0 12.2 0.5 0.3 1.5 

BoYs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 2.1 13.4 0.7 0.5 2.0 

Girls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 1.8 10.9 0.5 0.4 2.4 

Annual family income 

Under$6,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.9 5.9 18.5 1.4 1.3 3.6 

$6,000-14,999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 2.2 12.1 0.7 0.5 1.9 

$15,0000rmore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 0.7 2.8 0.4 0.3 1.2 

Degree of urbanization of place of residence 

Urban, lmillion personsormore . . . . . . . . . . . . . . . . . . . . . . . 7.2 4.0 15.2 0.7 0.7 1.5 

Central icy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6 4.5 18.6 1.9 1.9 2.8 

Non-central city . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7 3.8 3.3 0.8 0.8 1.4 

Urban,fewerthan l millionpersons . . . . . . . . . . . . . . . . . . . . . . . 3.5 1.6 10.2 0.6 0.4 2.4 

Rural . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 1.2 10.3 0.9 0.5 5.3 

lThe one child (a black mala, family incoma undar $6,000, in a rural araa) with an excessively high Pb-B level (76. O#g/dl) wasexcludad. This 

axclusion hasa negligiblaeffact on the national estimates shown hers. 

Zlncludes data for races not shown separately. 

3E~~imated using da~onbl~od l~adl~vei~ det~rmined fro~~pa=i~en$ drawn byvenipuncture, 

17 r


o~ 

1976 1977 1978 1979 1980 1981 

Year 

SOURCE: Adapted from reference 20. 

Figure7. Mean blood levels of U.S. population 6months-74 years: 

United States, February 1976-February 1980 

- . 

I 
admme&a 15


Jij 40 

35 

30 

25 

20 

15 

10 

5 

0 

Male Female Black White 0.5-5 6-17 1B-74 

Overall Sexl Race Age (years)l 

SOURCE: Adapted from reference 20. 

1Forwhite persons only. 

Figure8. Percent decrease inmeanblood lead levels of U.S. population 6months-74 years, bysex, race, and age: 

United States, February 1976-February 1980 
16 ackna?data


Summary 

For yew-s excessive exposure to lead has been a 

serious public health concern for selected groups of 

the population--porticularly young children and lead 

smelter and other industrial workers. This report provides the first national estimates of the blood lead 

levels in the U.S. population, based on the findings 

from the National Health and Nutrition Examination 

Survey of 1976-80 (NHANES H). Blood lead levels 

were determined on a cross-sectional sample representative of the U.S. civilim noninstitutionalized 

population 6 nlonths-74 years of age examined in 

NHANES 11. These data were obtained for baseline 

use in studies of the effect of lead contamination on 

health and for identifying areas or groups at high risk 

throughout the country. 

Based on the CDC guideline for elevated blood 

lead levels (30 micrograms or more per deciliter of 

whole blood), an estimated 4.0 percent or approximately 675,000 U.S. children ages 6 months-5 years 

show evidence of excessive amounts of lead in their 

blood. The percent of children with this degree of 

elevated blood lead level is significantly higher in 

black (1 2.2 percent) than in white (2.0 percent) 

children. Almost one-fifth (18.5 percent) of black 

children from low income families have elevated 

blood lead levels. 

Among children 6 months-5 years of age, mean 

blood lead levels are significantly higher in black than 

in white children across all family income levels and 

degrees of urbanization of their place of residence. 

Mean blood lead levels are significantly higher among 

children from families with low income levels and 

those in the large urbanized communities ( 1 million 

or more population) than among children from 

families with moderate or high income levels and 

those living in smaller cities or rural areas, respectively. 

Among children ages 6-17 years, mean blood lead 

levels decrease across successive age groups until 

about adolescence. For persons 18-74 years of age, 

mean blood lead levels are positively associated with 

age until the middle ages (45-54 year group), with a 

moderate decline in the older age groups. Across all 

adult age groups, the mean bloo~ I;ad ievels of men 

substantially exceed those of women. 

4 
� 

dmcedaa 17 

@ 

National Center for Health Statistics: Statistics needed for 

determining the effects of the environment on health, report 

of the technical consultant panel to the United States National 

Committee on Vital and Health Statistics. Vital and Health 

Statistics. Series 4-No. 20. DHEW Pub. No. (PHS) 79-1457. 

Public Health Service. Washington. U.S. Government Printing 

Office, July 1977. 

2National Center for Health Statistics, A. McDoweil, A. Engel, 

J. T. Massey, and K. Maurer: Plan and operation of the second 

National Health and Nutrition Examination Survey, 1976-

1980. Vital and Health Statistics. Series l-No. 15. DHHS Pub. 

No. (PHS) S 1-1317. Public Health Service. Washington. U.S. 

Government Printing Office, July 1981. 

3 Centers for Disease Control: Surveillance of childhood lead 

poisoning –United States. Morbidity and Mortality Weekly 

Report. Vol. 30, No. 34, DHHS Pub. No. (CDC) 81-8017. Public Health Service. Atlanta. U.S. Government Printing Office, 

Sept. 4, 19S1. pp. 438-439. 

4World Health Organization: Health Hazards of the Human 

Environment. Geneva. World Health Organization, 1972. 

5 National Center for Health Statistics: Blood lead levels of 

persons 6 months-74 years, United States, 1976-80. Vital and 

Health Statistics. Series 11. Public Health Service, DHHS, 

Hyattsville, Md. To be published. 

6Centers for Disease Control: Preventing lead poisoning in 

oung children. J. Pediatr. 93(4):709-720, Oct. 197% 

enters for Disease Control, E. W. Gunter, W. E. Turner, 

Neese. et al.: Laboratory procedures used by the Clinical 

hemistry Division, Centers for Disease Control, for the 

second National Health and Nutrition Examination Survey 

(NHANES II). Atlanta. 1981. 

8K. R. Mahaffey, J. L. Annest, H. E. Barbano, et al.: Preliminary analysis of blood lead concentrations for children and 

adults: HANES II, 1976-1980. Trace Substances in Environmental Health –XIH. pp. 37-51, D. D. Hemphill, Ed., Univ. of 

Missouri, Columbia, 1979. 

‘W. F. Barthel, A. L. Smrek, G. P. Angel, et al.: Modified 

Delves cup atomic absorption determination of lead in blood. 

J. Assoc. Offi Anal. Chem. 56:1253-56, 1973. 

1‘J. P. Crisler, N. T. Lao, L. C. Tang, et al.: A micro sampling 

method for the determination of blood lead. Microchem J. 

18:77-S4, 1973. 

1lK. R. Mahaffey: Relation between quantities of lead ingested and health effects of lead in humans. Pediatrics 59(3): 

44&56, Mar. 1977. 

12U.S. Environmental Protection Agency: Air quality criteria 

for lead. EPA Pub. No. 600/8-77-0 17, Office of Research and 

Development. Washington. U.S. Government Printing Office, 

1977. 

13J. S. Lin-Fu: Undue lead absorption and lead poisoning in 

children – an overview. In: Proceedings, In t. Con.K on Heavy 

Metals in the Environment, pp. 29-52. Toronto, Canada, Oct. 

27-31, 1975. 

14P. J. Landngan, E. L. Baker, R. H. Whitworth, et al.: Neuroepidemiologic evaluations of children with chronic increased 

lead absorption. In H. L. Needleman, cd., Low Lead Exposure: 

The Clinical Implications of Current Research. Raven Press, 

N.Y., 1980. pp. 17-33. 

15H. L. Needlema, c. Gunnoe, A. Leviton, et ~.: Deficits in 

psychologic and classroom performance of children with 

elevated dentine lead levels. Alew Eng. J. Med. 300(13): 689-

732, Mar. 1979. 

16 U.S. Bureau of the Census: Consumer income. Characteristics of the population below the poverty level: 1978. Current 

Population Reports. Series P-60, No. 124. Washington. U.S. 

Government Printing Office, July 1980. 

171. H. Billick, A. S. Curran, and D. R. Shier: Analysis of pediatric blood lead levels in New York City for 1970-1976. 

Environ. Hlth. Perspect. 31:183-192, Aug. 1979. 

1‘C. J. Cohen, G. N. Bowers, and M. L. Lepow: Epidemiology 

of lead poisoning, a comparison between urban and rural 

children. JAMA 226:1430-1433, 1973. 

19J. M. Simpson, J. L. Clark, R. S Challop, et al.: Elevated 

blood lead levels in children, a 27-city neighborhood survey. 

Hlth. Serv. Rept. 88:419422, 1972. 

20 Centers for Disease Control: Blood-lead levels in U.S. population. Morbidity and Wortality Weekl.v Report. Vol. 31, No. 

10. DHHS Pub. No. (CDC) 82-8017, Public Health Service. 

Atlanta. U.S. Government Printing Office, Mar. 19, 1982. pp. 

132-134. 

21 R. S. Woodruff: A simple method for approximating the 

variance of a complicated estimate. JASA 66:411-414, 1971. 

22 National Center for Health Statistics, P. J. McCarthy: Pseudoreplication, further evaluation and application of the balanced half-sample technique. Vital and Health Statistics. Series 

2-No. 31. DHEW Pub. No. (HSM) 73-1270. Health Services 

and Mental Health Administration. Washington. U.S. Government Printing Office, Jan. 1969. 

23 M. M. Holt: SURREGR, standard errom of regression coefficients from sample survey data. Unpublished. Research Triangle Institute, N.C., 1977. 

24J. E. Grizzle, C. F. Starmer, and G. G. Koch: AnaIysis of 

categorical data by linear models. Biometrics 25:489-504, 

1969. 

25 R. J. Landis, W. M. Stanish, J. L. Freeman, et al.: A computer program for the generalized chi-square analysis of categorical data using weighted least squares (GENCAT). Comput. 

Programs Biomed. 6:196-231, 1976. 

26D. Makuc: Interfacing SURREGR and GENCAT to analyze 

complex surveys. Proc. Amer. Stat. Assoc., Statistical Computing Section, pp. 16-19, 1981. 

27 H. T. Delves: A micro-sampling method for the rapid determination of lead in blood by atomic-absorption spectroscopy. Analyst. 95:43 1+38, 1970. 

2SJ. hl. Hunter: The summer disease, an integrative model of 

the seasonality aspects of childhood lead poisoning. Sot. Sci. 

Med. 11:691-703, 1977. 
18 acklncedata


symbols 

.-. Data not available 

. . . Category not applicable 

Quantity zero 

0.0 Quantity more than zero but less than 

0.05 

z	 Quantity more than zero but less than 

500 where numbers are rounded to 

thousands 

* Figure does not meet standards of 

reliability or precision 

,., 

& 
adwincedata 19


chnical notes 

Sam ple design 

The information presented in this report is based 

on data from the direct standardized physical examination, tests and measurements, and medical histories 

collected in the second National Health and Nutrition 

Examination Survey (NHANES II) during 1976-80. 

The target population of NHANES II encompassed 

the civilian noninstitutionalized population (ages 6 

months through 74 years) of the United States, including Alaska and Hawaii. 

NHANES II utilized a multistage probability design that involved selection of primary sampling units 

(PSU’S), segments (clusters of households) within 

PSU’S, households, eligible persons, and finally sample persons. PSU’S are typically composed of a county 

or group of contiguous counties. The sample design 

provided for oversampling among those p~rsons ages 

6 months-5 years, those ages 60-74 yeafi; and those 

living in poverty areas (as deiined by the United 

States Bureau of the Census for the 1970 census16 ). 

The U.S. Bureau of the Census selected the 

NHANES H sample of 27,80 I persons according to 

edifications from the National Center for Health 

D’ tatistics. Of this sample, 20.322 (73.1 percent) were 

examined. A total of 16,563 persons in the NHANES 

II sample, including all persons ages 6 months-6 years 

and a half-sample of persons ages 7-74 years, were assigned to receive the test for lead levels in the blood. 

Of these sample persons, blood specimens were drawn 

and analyzed for blood lead on 10,049 persons giving 

an overall response rate of 60.7 percent. 

Blood lead Ievels and related data in this report 

are presented as population estimates; examination 

fiidings for each sample person have been inflated by 

the reciprocal of selection probabilities, adjusted to 

account for persons who were not examined, and 

poststratified by race, sex, and age. The final estimates will then closeIy approximate the independent 

U.S. Bureau of Census estimates for the civilian noninstitutionalized population of the United States as of 

March 1, 1978. No further adjustment was made for 

examined persons in the lead subsample with missing 

blood lead data due to refusal to give a blood specimen or otherwise. 

,- Standard errors and tests of significance - The statistical methods used to analyze the data 

e into account the complex survey design of 

e HANES 11.2 Complex survey techniques were used 

to decrease the cost of sampling a large population. 

Although complex survey designs complicate data 

NOTE A list of references follows the text. 

analysis, they must be taken into consideration to 

avoid the erroneous assumptions that would be made 

using a simple random sampling method. The latter 

usually results in an inferential analysis with too 

many significant test results due solely to underestimation of variances. 

The standard errors of the weighted means and 

proportions of persons with elevated blood lead levels 

presented in this report were calculated using the 

Taylor Series linearization method.~1 This process 

approximates the variance of nonlinear statistics, 

e.g., means and proportions, by using a first order 

Taylor Series expansion. If the higher order terms of 

the expansion are negligible, and if 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 analyzing NHANES II data.zz 

For blood lead analysis in this study, the population was divided into three age groups–children 

months-5 years, youths 6-17 years, and adults 18-74 

years. Regression analysis was performed within each 

age group using blood lead level as the dependent 

variable and age as a covariate. The effect on blood 

lead Ieve] of each of the demographic variables-race, 

sex, income, and degree of urbanization-were tested 

in this analysis after accounting for age. Tests of significance for comparing the means shown in figure 1 

through 6 were performed using a regression program, 

called SURREGR,ZS which takes into consideration 

the complex survey sample design. 

Using the Grizzle-Starrier-Koch (GSK) approach 

to categorical data analysis,~A tests of the hypothesis 

that there is no difference among population subgroups in proportions of persons with elevated blood 

lead levels (table 7) were performed. This analysis involved two stages, ( 1) estimation of the proportion of 

those with elevated blood lead levels for the subgroups of interest and (2) estimation of an appropriate variance-covariance matrix and hypothesis testing 

using categorical data analysis. The computation for 

this analysis involved interfacing two programs– 

SURREGR for the first stage calculations and GENCAT, a program for generalized chi-square analysis 

of categorical data, for the second stage.2G~27 

Description of nonrespondents 

and exclusions 

All NHANES .11 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 partici6 
20 aduancedata 

pation in the survey. The rate of nonresponse was 

greater among preschool-aged children than among 

youths or adults (table I). 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 II), those with missing 

blood lead values were randomly distributed by demographic (other than age) and socioeconomic categories. The analysis of the distribution of nonresponse for noninterviewed and nonexamined persons 

in these categories is planned for a forthcoming 

reports 

Blood lead data from blood specimens drawn by 

fingerstick (pricking the finger) and from extreme 

cases of lead exposure (blood lead values of 70.0 

vg/dl or more) were excluded from computation of 

national estimates. A description of blood lead levels 

for persons receiving fingersticks is given in table III. 

Seventy-five percent of the 113 children with blood 

lead values who received fingersticks were under 3 

years of age. Table IV shows the characteristics of 

three persons receiving venipunctures who had blood 

lead values greater than 70.0 pg/dl. Each of these 

three individuals was referred to his personal physician for medical attention. 

Quality control methods 

Lead concentrations were measured in whole 

blood by atomic absorption spectroscopy using a 

modification of the Delves method.9 Y27 All materials 

used for collecting and processing specimens were 

screened for possible lead contamination. All preparatory work on the specimens, including field and laboratory procedures, were conducted under laminar 

flow hoods that provided class 100 air (i.e., air conNOTE: A list of references follows the text. 

taining less than 100 particles/m3 of greater than 0.5 

micron diameter). 

Two quality control systems using bovine w 

blood were set up by CDC, These two systems w @

(1) “bench” quality control pools inserted by the 

analyst and measured 2-4 times in each analytical run 

to make judgments on the day of analysis and (2) 

“blind” quality control specimens placed in vials, 

labeled, and processed in duplicate to be indistinguishable from regular NHANES II specimens. If the 

average of replicate values of either “bench” or 

“blind” quality control specimens fell outside of their 

respective previously established 95-percent confidence limits, the run was repeated. Also, NHANES II 

specimens were run in duplicate. When replicate 

absorbance values differed by more than 0.025 

absorbance or the difference between calculated concentrations for duplicates was greater than 7&g Pb/dl, 

analysis was repeated for the specimen. 

The “normal blind” pool with a mean of 13.7 

pg/dl had a standard deviation (SD) of 2.2 pg/dl 

(0.022 ppm) while the “high blind” pool with a mean 

of 25.5 ~g/dl had a SD of 3.2 ~g/dl (0.032 ppm). The 

coefficients 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- bloo~ lead levels of 30,0 ~g~dl or more 

ranged from 7.0 to 15.0 percent.T 

4 

Limitations of the data 

Rigorous quality control methods were implemented throughout specimen collection and processing and in data processing to ensure 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,g the coefficient of variation for the laboratory methods used are approximately 15.0 percent 

Table 1. Nonresponse among sample persons ages 6 months-74 years in the lead subsample by age: National Health and Nutrition Examination 

Survey, 1976-80 

Number of sample persons 

Examined but missing 

blood lead values 

Age In lead Inter- Not intarExamined exaNm~.~ed Refused subsamp te vie wed vie wed Blood 

Overall to give specimen blood drawn 7 specimen 

Percent of Percent of 

sample examinees2 

persons2 without 

without lead 

lead values 

values 

Alleges . . . . . . . . . . . 16,563 15,179 1,384 12,288 2,891 2,239 

6 months-5 years . . . 5,069 4,876 193 4,118 758 1,634 1: “:: m 

6-17 years . . . . . . . . . 2,413 2,261 152 1,967 294 245 122 123 28.6 12,5 

18-74 years .,...,... 9,081 8,042 1,039 6,203 1,839 360 87 273 35.7 5.8 

1 By “enipuncture or fingerstick. 

Zln the lead subsample, 
““’ Table II. Nonresponse among examined Persons a9es 6 mOnths-74 Yea lead subsample by age, race, sex, income, and degree Of urbanization: 

National Health and Nutrition Examination Survey, 1976-80 

Age 

6 mon ths-74 years 6 months-5 years 6-17 years 18-74 years 

Demographic variables Examined persons Examined persons Examined persons Examined persons 

Number of with missing Number of with missing Number of with missing Number of with missing 

persons lead values persons lead values persons Iced values persons lead values 

examined examined examined examined 

Number Percent Number Percent Number Percent Number Percent 

- Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12,288 2,239 18.2 4,118 1,634 39.7 1,967 245 12.5 6,203 360 

Race 

White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Sex 

Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Annual family income 

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

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

$15,0000rmore . . . . . . . . . . . . . . . . . . . . . 

Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . 

Degraa of urbanization 

Largaurban’ . . . . . . . . . . . . . . . . . . . . . . . . . Smallerurban2 . . . . . . . . . . . . . . . . . . . . . . . 

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

lwli~h 1 ~illion ormorepersons. 

2Withfe~erthan I millirmpersolls, 

10,253 1,806 17.6 3,264 1,311 40.2 1,616 192 11.9 5,373 303 5.6 

1,737 367 21.1 723 269 37.2 313 46 15.3 701 50 7.1 

298 66 22.1 131 54 41.2 38 5 13.2 129 7 5.4 

6,123 1,119 18.3 2,143 840 39.2 1,022 119 11.6 2,958 160 5.4 

6,165 1,120 18.2 1,975 794 40.2 945 126 13.3 3,245 200 6.2 

2,291 404 17.6 752 281 37.4 268 37 13.8 1,271 86 6.8 

5,082 994 19.6 1,876 739 39.4 780 107 13.7 2,426 148 6.1 

4,509 758 16.8 1,368 562 41.1 852 91 10.7 2,289 105 4.6 

406 83 20.4 122 52 42.6 67 10 14.9 217 21 9.7 

2,993 583 19.5 949 391 41.2 483 69 14.3 1,561 123 7.9 

4,805 869 18.1 1,647 639 38.8 721 81 11.2 2,437 149 6.1 

4,490 787 17.5 1,522 604 39.7 763 95 12.5 2,205 88 4.0 

5.8
22 ZKIWdand 12.0 percent for control pools with low (less than 

30.0 pg/dl) tincl high (30.0 pg/dl or more) mean lead 

levels, respectively. In addition, there are significant 

within-day and amongday components of variance. 

A possible logistical factor indirectly influencing 

the blood lead data is the itinerary of the Mobile Examination Centers (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 le 

levels associated with seasonalityzg and geograp 

location may be confounded, to some undetermin a 

degree, with those associated with degree of urbanization of place of residence. 

NOTE: A Listof references follows the text. I 

. 

b i 
akmdata 23 

Table 111. Description of raw data on blood lead determinations from specimens collected by finge;sticks in children ages 6 month s-7 yews: 

National Health and Nutrition Examination Suwey,1976.80 . . 

Number Standard Race Mean Mode Median Minimum Maximum Skewness examined deviation 

(pgldl) 

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 

1 I nclude$ data for races not shown separately. 

Table IV. Characteristics of three persons with blood Ieadvalues greater than 70.Oflg/dl whoreceived venipuncture: National Health and Nutrition 

Examination Survey, 1976-80 

Demographicfac tors 

Blood lead value 

(vg/dl) Age in Sex Race Family Degree of 

years income urbanization 

.— 

76.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Male Black Under $6,000 Rural€

80.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Male White $15,000 or more Large urbanl€

90.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Male Black Under$6,000 Smaller urbanz€

lWith 1 million or more persons. 

Zwith fewer than 1 million persons. 
24 adual’KxMb 

Recent Issues of Advance Data From Vital and Health Statistics 

No. 78. Drugs Most Frequently Used in Office-Based Practice: 

National Ambulatory Medicsl Care Survey, 1980 (Issued: 

May 12, 1982) 

No. 77. 1980 Summary: National Ambulatory Medical Care 

Survey (Issued: February 22, 1982) 

No. 76. Blood Carbon Monoxide Levels in Persons 3-74 Years 

of Age: United States, 1976-80 (Issued: March 17, 1982) 

SUGGESTED CITATION


National Center for Health Statistics, J. L. Annest,


K.R. Mahaffey, D.H. Cox, and J. Roberts: Blood


Iaad levels for persons 6 months -74 years of age:


United States, 1976-80. Advarrce Data From Vita/


and Health Statistics, No, 79. DHHS Pub. No.


(PHS) 82-1250. Public Health Service, Hyattsville,


Md., May 12, 1982.


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