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Topic: RSS FeedBlood lead levels and sexual maturation in U.S. girls: the Third National Health and Nutrition Examination Survey, 1988-1994 - Children's Health
Environmental Health Perspectives, May, 2003 by Tiejian Wu, Germaine M. Buck, Pauline Mendola
Table 1. Characteristics of the study samples: NHANES III, 1988-1994.
Sample 1 (girls 8-16 years old)
Characteristic Unweighted Weighted
Race/ethnicity (%)
Non-Hispanic white 25.6 65.0
Non-Hispanic African American 34.8 16.2
Mexican American 35.1 8.8
Other 4.6 10.0
Age in years (mean [ or -] SD) 12.2 [ or -] 2.6 12.4
Family size (%)
1-2 17.2 18.2
3-6 66.3 70.3
[greater than or equal to] 7 16.5 115.0
Residency (%)
Nonmetropolitan 53.4 54.7
Metropolitan 46.6 45.3
Poverty income ratio (%)
Unknown 7.3 4.1
< 1 36.8 23.6
1-2 25.3 23.4
> 2 30.7 48.9
Blood lead [[micro]g/dL (%)]
0-2.0 54.3 66.9
2.1-4.9 35.2 27.2
5.0-21.7 10.4 5.9
BMI (mean [ or -] SD) 20.5 [ or -] 4.7 20.2
Sample 2 (girls 10-16 years old)
Characteristic Unweighted Weighted
Race/ethnicity (%)
Non-Hispanic white 25.3 64.5
Non-Hispanic African American 34.3 16.0
Mexican American 35.6 9.5
Other 4.9 10.0
Age in years (mean [ or -] SD) 13.3 [ or -] 2.0 13.5
Family size (%)
1-2 17.2 17.8
3-6 66.9 72.6
[greater than or equal to] 7 15.9 9.6
Residency (%)
Nonmetropolitan 53.7 55.4
Metropolitan 46.3 44.6
Poverty income ratio (%)
Unknown 7.0 4.2
< 1 35.3 20.4
1-2 26.2 23.5
> 2 31.5 51.9
Blood lead [[microg/dL (%)]
0-2.0 60.2 71.8
2.1-4.9 32.9 24.1
5.0-21.7 7.0 4.1
BMI (mean [ or -] SD) 21.4 [ or -] 4.7 21.0
Sample 1 (n = 1,706) includes girls with Tanner staging and blood lead
information; sample 2 (n = 1,235) contains a subset of girls from
sample 1 [greater than or equal to] 10 years old with menarche
information. Weighted statistics are calculated with the application
of weights established for the NHANES III exam sample.
Table 2. Unweighted percentage of girls at Tanner stage 2 for pubic
hair and breast development and attainment of menarche, by age and
blood lead level: NHANES III, 1988-1994.
0.7-2.0 [micro]g/dL 2.1-4.9 [micro]g/dL
Age (years) No. Percent No. Percent
Pubic hair
8 75 18.7 70 15.7
9 88 36.4 102 36.3
10 90 60.0 82 51.2
11 94 85.1 101 74.3
12 108 97.2 74 96.0
13 112 98.2 56 100.0
14 111 99.1 48 100.0
15 125 100.0 27 100.0
16 123 100.0 42 100.0
Breast development
8 75 26.7 70 22.9
9 88 36.4 102 35.3
10 90 61.1 82 72.0
11 94 90.4 101 87.1
12 108 98.2 74 96.0
13 112 99.1 56 98.2
14 111 99.1 48 100.0
15 125 100.0 27 100.0
16 123 100.0 42 100.0
Attainment of menarche
10 85 5.9 74 2.7
11 90 30.0 99 16.2
12 103 68.0 70 44.3
13 110 87.3 53 79.3
14 110 97.3 46 87.0
15 123 100.0 26 100.0
16 122 99.2 38 100.0
5.0-21.7 [micro]g/dL
Age (years) No. Percent p-Value
Pubic hair
8 43 7.0
9 41 19.5
10 36 44.4 0.022
11 25 80.0
12 14 85.7
13 7 100.0
14 6 100.0
15 4 100.0
16 2 100.0
Breast development
8 43 11.6
9 41 34.2
10 36 61.1 0.520
11 25 84.0
12 14 100.0
13 7 100.0
14 6 100.0
15 4 100.0
16 2 100.0
Attainment of menarche
10 33 0.0
11 22 9.1
12 13 38.5 0.091
13 6 50.0
14 6 83.3
15 5 100.0
16 2 100.0
p-Values are from Cochran-Mantel Haenszel chi-square test of the
percentage differences across blood lead levels controlling for
age and after weighting and adjusting for NHANES III complex
sampling using SUDAAN software.
Table 3. Unweighted mean blood lead levels ([micro]g/dL) by age and
presence/absence of Tanner stage 2 pubertal measure and menarche:
NHANES III, 1988-1994.
Absence of pubertal measure
Age (years) No. Mean [ or -] SD
Pubic hair
8 160 3.5 [ or -] 2.6
9 154 3.5 [ or -] 2.6
10 96 3.7 [ or -] 3.6
11 45 3.2 [ or -] 2.7
12 8 4.1 [ or -] 4.7
13 2 1.3 [ or -] 0.8
14 1 0.7
15
16
Breast development
8 147 3.6 [ or -] 2.6
9 149 3.4 [ or -] 2.8
10 72 3.4 [ or -] 3.8
11 26 3.4 [ or -] 2.6
12 5 2.0 [ or -] 1.3
13 2 1.4 [ or -] 1.0
14 1 0.7
15
16
Attainment of menarche
10 185 3.3 [ or -] 3.0
11 166 3.0 [ or -] 2.3
12 80 2.8 [ or -] 2.5
13 28 2.8 [ or -] 2.4
14 10 2.5 [ or -] 1.8
15 1 0.7
16
Presence of pubertal measure
Age (years) No. Mean [ or -] SD p-Value
Pubic hair
8 28 2.4 [ or -] 1.4
9 77 3.1 [ or -] 2.9
10 112 2.8 [ or -] 2.1 0.013
11 175 2.8 [ or -] 2.1
12 188 2.2 [ or -] 1.7
13 173 2.0 [ or -] 1.5
14 164 1.9 [ or -] 1.5
15 156 1.5 [ or -] 1.2
16 167 1.6 [ or -] 1.0
Breast development
8 41 2.6 [ or -] 2.1
9 82 3.1 [ or -] 2.6
10 136 3.1 [ or -] 2.4 0.552
11 194 2.8 [ or -] 2.2
12 191 2.3 [ or -] 1.9
13 173 2.0 [ or -] 1.5
14 164 1.9 [ or -] 1.5
15 156 1.5 [ or -] 1.2
16 167 1.6 [ or -] 1.0
Attainment of menarche
10 7 1.3 [ or -] 0.7
11 45 2.1 [ or -] 1.3
12 106 2.0 [ or -] 1.3 0.053
13 141 1.8 [ or -] 1.2
14 152 1.8 [ or -] 1.5
15 153 1.5 [ or -] 1.2
16 161 1.6 [ or -] 1.0
p-Values are for the mean difference in blood lead (natural log
transformed) between presence and absence of a puberty milestone after
controlling for age using ANOVA with application of weights and the
adjustment for NHANES III complex sampling using SUDAAN software.
Table 4. Likelihood (a) of having attained pubertal markers by
blood lead levels: NHANES III, 1988-1994.
Pubic hair Breast development
Blood lead ([micro]g/dL) 0R 95% CI OR 95% CI
0.7-2.0 1.00 Reference 1.00 Reference
2.1-4.9 0.48 0.25-0.92 1.51 0.90-2.53
5.0-21.7 0.27 0.08-0.93 1.20 0.51-2.85
Log transformed (b) 0.54 0.32-0.91 1.20 0.76-1.92
Attainment of menarche
Blood lead ([micro]g/dL) OR 95% CI
0.7-2.0 1.00 Reference
2.1-4.9 0.42 0.18-0.97
5.0-21.7 0.19 0.08-0.43
Log transformed (b) 0.52 0.28-0.97
Abbreviations: 95% CI, 95% confidence interval; OR, odds ratio.
(a) Logistic regression with adjustment for age, race/ethnicity,
poverty income ratio, metro residence, family size, and BMI using
SUDAAN software and weights established for the NHANES III exam
sample. (b) Natural log transformed, treated as a continuous variable.
The categorical and continuous variables of blood lead were analyzed
in separate models.
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