Table1: The characteristics of participants
Characteristics
|
Blood lead (ug/dl)
|
Q1(0.18-0.55)
|
Q2(0.56-0.76)
|
Q3(0.77-1.10)
|
Q4(1.11-16.8)
|
p-value
|
n=801
|
n=853
|
n=836
|
n=841
|
|
Age (years)
|
15.12±1.87
|
15.30±1.89
|
14.95±1.97
|
14.64±1.98
|
<0.001
|
Sex (%)
|
|
|
|
|
<0.001
|
Male
|
32.33
|
47.17
|
62.07
|
75.01
|
|
Female
|
67.67
|
52.83
|
37.93
|
24.99
|
|
Race (%)
|
|
|
|
|
<0.001
|
Mexican American
|
13.78
|
11.48
|
10.52
|
15.00
|
|
Other Hispanic
|
5.21
|
5.58
|
5.20
|
7.53
|
|
Non-Hispanic White
|
69.21
|
63.00
|
60.26
|
50.06
|
|
Non-Hispanic Black
|
8.15
|
13.07
|
16.59
|
18.92
|
|
Other Race - Including Multi-Racial
|
3.65
|
6.87
|
7.43
|
8.49
|
|
PIR
|
3,14±1.62
|
2.99±1.58
|
2.48±1.62
|
2.15±1.59
|
<0.001
|
BMI (kg/m2)
|
|
|
|
|
0.016
|
<18.5
|
11.40
|
15.17
|
16.53
|
18.10
|
|
18.5-24
|
51.28
|
49.71
|
48.52
|
49.37
|
|
24-28
|
19.00
|
16.61
|
18.93
|
17.39
|
|
≥28
|
18.32
|
18.51
|
16.02
|
15.14
|
|
Waist (cm)
|
82.19±13.47
|
80.79±13.26
|
80.07±13.58
|
79.47±13.26
|
<0.001
|
WBC (1000/ul)
|
7.08±1.86
|
6.97±1.92
|
7.02±1.93
|
6.97±1.90
|
0.583
|
RBC (10*6/ul)
|
4.63±0.41
|
4.77±0.44
|
4.87±0.45
|
4.96±0.43
|
<0.001
|
PLT (10*3/ul)
|
274.86±70.51
|
273.33±65.61
|
274.04±62.26
|
282.01±73.02
|
<0.001
|
Hb (g/dl)
|
13.85±1.23
|
14.25±1.25
|
14.29±1.31
|
14.41±1.34
|
<0.001
|
Serum albumin (g/dl)
|
4.39±0.31
|
4.43±0.29
|
4.43±0.30
|
4.44±0.28
|
0.006
|
Blood urea nitrogen (mg/dl)
|
10.10±2.88
|
10.28±3.10
|
10.49±3.71
|
10.36±3.16
|
0.082
|
Serum uric acid (mg/dl)
|
4.77±1.61
|
5.10±1.19
|
5.11±1.16
|
5.35±1.24
|
<0.001
|
Serum phosphorus (mmol/dl)
|
3.04±1.53
|
3.38±1.52
|
3.70±1.56
|
3.83±1.47
|
<0.001
|
Serum calcium (mmol/l)
|
2.40±0.08
|
2.42±0.08
|
2.42±0.08
|
2.43±0.08
|
<0.001
|
Serum iron (ug/dl)
|
85.46±38.26
|
91.94±36.90
|
88.80±37.44
|
87.46±39.01
|
0.003
|
Total femur BMD (g/cm2)
|
0.98±0.15
|
0.99±0.16
|
0.97±0.16
|
0.96±0.16
|
0.005
|
Femur neck BMD (g/cm2)
|
0.90±0.14
|
0.92±0.15
|
0.90±0.15
|
0.89±0.15
|
0.001
|
Trochanter BMD (g/cm2)
|
0.76±0.13
|
0.78±0.14
|
0.77±0.14
|
0.76±0.13
|
0.003
|
Intertrochanter BMD (g/cm2)
|
1.12±0.17
|
1.14±0.18
|
1.11±0.19
|
1.10±0.18
|
<0.001
|
Mean ± SD for continuous variables: P value was calculated by weighted linear regression model % for Categorical variables: P value was calculated by weighted chi-square test.
PIR: Poverty income ratio; BMI: body mass index; WBC: White blood cell count; RBC: Red blood cell count; PLT: Platelet count; Hb: hemoglobin; BMD: bone mineral density
Table2: Association between Blood lead (ug/dl) and Total femur BMD (g/cm2)
|
|
Model 1 β (95% CI) P-value
|
Model 2 β (95% CI) P-value
|
Model 3 β (95% CI) P-value
|
Total femur BMD (g/cm2)
|
Blood lead (ug/dl)
|
-0.013(-0.020,-0.005) 0.001
|
-0.017(-0.024,-0.010) <0.001
|
-0.008 (-0.014,-0.001)0.018
|
|
Q1(0.18-0.55)
|
Reference (0)
|
Reference (0)
|
Reference (0)
|
|
Q2(0.56-0.76)
|
0.017(0.002,0.031) 0.021
|
-0.001(-0.014,0.011) 0.825
|
0.003(-0.009,0.014) 0.636
|
|
Q3(0.77-1.10)
|
-0.004(-0.019,0.011) 0.592
|
-0.023(-0.036,-0.009) <0.001
|
-0.012(-0.025,-0.000) 0.049
|
|
Q4(1.11-16.8)
|
-0.015(-0.031,0.000) 0.051
|
-0.033(-0.048,-0.019) <0.001
|
-0.018(-0.032,-0.005) 0.009
|
|
P for trend
|
0.013
|
<0.001
|
0.002
|
Subgroup analysis stratified by gender
|
|
|
|
|
|
Male
|
-0.020(-0.030,-0.010) <0.001
|
-0.011(-0.019,-0.003) 0.010
|
-0.005(-0.013,0.003) 0.219
|
|
Female
|
-0.028(-0.041,-0.015) <0.001
|
-0.024(-0.036,-0.012) <0.001
|
-0.012(-0.025,-0.000) 0.047
|
Subgroup analysis stratified by race
|
|
|
|
|
|
Mexican American
|
-0.006(-0.016,0.004) 0.237
|
-0.012(-0.021,-0.003) <0.001
|
-0.007(-0.016,0.001) 0.095
|
|
Other Hispanic
|
0.002(-0.022,0.026) 0.860
|
-0.003(-0.025,0.020)0.805
|
-0.008(-0.030,0.015) 0.505
|
|
Non-Hispanic White
|
-0.020(-0.036,-0.004) 0.016
|
-0.021(-0.035,-0.006) 0.007
|
-0.011(-0.024,0.003) 0.121
|
|
Non-Hispanic Black
|
-0.018(-0.031,-0.005) 0.005
|
-0.014(-0.026,-0.002) 0.019
|
-0.001(-0.013,0.010) 0.800
|
|
Other Race - Including Multi-Racial
|
-0.012 (-0.058,0.034) 0.612
|
-0.008(-0.049,0.034) 0.726
|
0.012(-0.032,0.056) 0.593
|
Model 1 no covariates were adjusted.
Model 2 Age, Gender (male, female), and Race (Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, Other Race - Including Multi-Racial) were adjusted.
Model 3 Age, Gender (male, female), Race (Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, Other Race - Including Multi-Racial), Poverty income ratio, BMI (<18.5,18.5-24,24-28,≥28), Waist, White blood cell count, Red blood cell count, Platelet count, hemoglobin, Serum albumin, Blood urea nitrogen, Serum uric acid ,Serum phosphorus, Serum calcium, Serum iron were adjusted.
Subgroup analysis stratified by gender: Model does not contain gender
Subgroup analysis stratified by race:Model does not contain race
Table3: Association between Blood lead (ug/dl) and Femur neck BMD (g/cm2)
|
|
Model 1 β (95% CI) P-value
|
Model 2 β (95% CI) P-value
|
Model 3 β (95% CI) P-value
|
Femur neck BMD (g/cm2)
|
Blood lead (ug/dl)
|
-0.012(-0.019,-0.004) 0.002
|
-0.015(-0.021,-0.008) <0.001
|
-0.007(-0.014,-0.001) 0.024
|
|
Q1(0.18-0.55)
|
Reference (0)
|
Reference (0)
|
Reference (0)
|
|
Q2(0.56-0.76)
|
0.012(-0.002,0.026) 0.083
|
-0.003(-0.015,0.010) 0.654
|
0.002(-0.009,0.013) 0.769
|
|
Q3(0.77-1.10)
|
-0.007(-0.021,0.007) 0.310
|
-0.022(-0.034.-0.009)0.001
|
-0.012(-0.024,-0.000) 0.043
|
|
Q4(1.11-16.8)
|
-0.017(-0.031,-0.002) 0.025
|
-0.030(-0.044,-0.016 ) <0.001
|
-0.017(-0.030,-0.004) 0.011
|
|
P for trend
|
0.003
|
<0.001
|
0.003
|
Subgroup analysis stratified by gender
|
|
|
|
|
|
Male
|
-0.018(-0.027,-0.009) <0.001
|
-0.010(-0.018.-0.002) 0.012
|
-0.006(-0.013,0.002)0.131
|
|
Female
|
-0.022(-0.035,-0.009) <0.001
|
-0.018(-0.031.-0.006) 0.004
|
-0.008 (-0.020,0.004)0.213
|
Subgroup analysis stratified by race
|
|
|
|
|
|
Mexican American
|
-0.009 (-0.018,0.001) 0.078
|
-0.013(-0.022,-0.005) 0.003
|
-0.010(-0.018,-0.002) 0.017
|
|
Other Hispanic
|
0.014(-0.009,0.038) 0.239
|
0.014(-0.009,0.037) 0.233
|
-0.010(-0.018,-0.002) 0.017
|
|
Non-Hispanic White
|
-0.019(-0.034,-0.004) 0.014
|
-0.018(-0.033,-0.004)0.0119
|
-0.010(-0.024,0.003) 0.118
|
|
Non-Hispanic Black
|
-0.018(-0.031,-0.006) 0.003
|
-0.014(-0.025,-0.002) 0.021
|
-0.002(-0.013,0.009) 0.742
|
|
Other Race - Including Multi-Racial
|
-0.001(-0.044,0.042) 0.962
|
0.008(-0.031,0.046) 0.702
|
0.020(-0.019,0.059) 0.308
|
Model 1 no covariates were adjusted.
Model 2 Age, Gender (male, female), and Race (Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, Other Race - Including Multi-Racial) were adjusted.
Model 3 Age, Gender (male, female), Race (Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, Other Race - Including Multi-Racial), Poverty income ratio, BMI (<18.5,18.5-24,24-28,≥28), Waist, White blood cell count, Red blood cell count, Platelet count, hemoglobin, Serum albumin, Blood urea nitrogen, Serum uric acid ,Serum phosphorus, Serum calcium, Serum iron were adjusted.
Subgroup analysis stratified by gender: Model does not contain gender
Subgroup analysis stratified by race:Model does not contain race
Table4: Association between Blood lead (ug/dl) and Trochanter BMD (g/cm2)
|
|
Model 1 β (95% CI) P-value
|
Model 2 β (95% CI) P-value
|
Model 3 β (95% CI) P-value
|
Trochanter BMD (g/cm2)
|
Blood lead (ug/dl)
|
-0.009(-0.015,-0.002) 0.010
|
-0.015(-0.021,-0.009) <0.001
|
-0.007(-0.013,-0.001) 0.020
|
|
Q1(0.18-0.55)
|
Reference (0)
|
Reference (0)
|
Reference (0)
|
|
Q2(0.56-0.76)
|
0.019(0.006,0.031) 0.003
|
0.003(-0.008,0.015) 0.558
|
0.007(-0.003,0.018) 0.177
|
|
Q3(0.77-1.10)
|
0.004(-0.009,0.017) 0.553
|
-0.016(-0.027,-0.004) 0.0109
|
-0.006(-0.017,0.006) 0.329
|
|
Q4(1.11-16.8)
|
-0.004(-0.017,0.010) 0.592
|
-0.025(-0.038,-0.012) <0.001
|
-0.011(-0.024,0.002) 0.102
|
|
P for trend
|
0.073
|
<0.001
|
0.008
|
Subgroup analysis stratified by gender
|
|
|
|
|
|
Male
|
-0.017(-0.026,-0.008) <0.001
|
-0.010(-0.017,-0.002) <0.001
|
-0.005(-0.012,0.003) 0.217
|
|
Female
|
-0.024(-0.035,-0.013)<0.001
|
-0.022(-0.033,-0.011) <0.001
|
-0.011(-0.023,-0.000)0.05
|
Subgroup analysis stratified by race
|
|
|
|
|
|
Mexican American
|
-0.005(-0.013,0.004) 0.272
|
-0.011(-0.018,-0.003) 0.008
|
-0.008(-0.016,-0.000) 0.040
|
|
Other Hispanic
|
0.011(-0.009,0.032) 0.271
|
0.004(-0.016,0.024) 0.6791
|
0.009(-0.011,0.029) 0.376
|
|
Non-Hispanic White
|
-0.015(-0.030,-0.001) 0.031
|
-0.020(-0.034,-0.007) 0.003
|
-0.012(-0.025,0.001) 0.067
|
|
Non-Hispanic Black
|
-0.009(-0.020,0.002) 0.094
|
-0.011(-0.022,-0.001) 0.037
|
0.000(-0.010,0.010) 0.977
|
|
Other Race - Including Multi-Racial
|
-0.007(-0.044,0.030) 0.713
|
-0.009(-0.044.0.026) 0.611
|
0.009(-0.030,0.048) 0.647
|
Model 1 no covariates were adjusted.
Model 2 Age, Gender (male, female), and Race (Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, Other Race - Including Multi-Racial) were adjusted.
Model 3 Age, Gender (male, female), Race (Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, Other Race - Including Multi-Racial), Poverty income ratio, BMI (<18.5,18.5-24,24-28,≥28), Waist, White blood cell count, Red blood cell count, Platelet count, hemoglobin, Serum albumin, Blood urea nitrogen, Serum uric acid ,Serum phosphorus, Serum calcium, Serum iron were adjusted.
Subgroup analysis stratified by gender: Model does not contain gender
Subgroup analysis stratified by race:Model does not contain race
Table5: Association between Blood lead (ug/dl) and Intertrochanter BMD (g/cm2)
|
|
Model 1 β (95% CI) P-value
|
Model 2 β (95% CI) P-value
|
Model 3 β (95% CI) P-value
|
Intertrochanter BMD (g/cm2)
|
Blood lead (ug/dl)
|
-0.016(-0.025,-0.007) <0.001
|
-0.019(-0.027,-0.011) <0.001
|
-0.008(-0.016,-0.001)0.028
|
|
Q1(0.18-0.55)
|
Reference (0)
|
Reference (0)
|
Reference (0)
|
|
Q2(0.56-0.76)
|
0.016(-0.001,0.032) 0.062
|
-0.005(-0.019,0.010) 0.53423
|
-0.001(-0.014,0.012) 0.874
|
|
Q3(0.77-1.10)
|
-0.011(-0.028,0.006) 0.206
|
-0.029(-0.044,-0.013) <0.001
|
-0.018(-0.032,-0.004) 0.012
|
|
Q4(1.11-16.8)
|
-0.025(-0.043,-0.007) 0.006
|
-0.040(-0.056,-0.023) <0.001
|
-0.024(-0.040.-0.008)0.003
|
|
P for trend
|
<0.001
|
<0.001
|
<0.001
|
Subgroup analysis stratified by gender
|
|
|
|
|
|
Male
|
-0.023(-0.035,-0.011) <0.001
|
-0.012(-0.021,-0.002) 0.015
|
-0.005(-0.014,0.004) 0.281
|
|
Female
|
-0.033(-0.048,-0.018) <0.001
|
-0.027(-0.041.-0.013) <0.001
|
-0.014(-0.028,-0.000) 0.05
|
Subgroup analysis stratified by race
|
|
|
|
|
|
Mexican American
|
-0.006(-0.017,0.006) 0.322
|
-0.012(-0.022,-0.001) 0.026
|
-0.005(-0.015,0.004) 0.272
|
|
Other Hispanic
|
-0.007(-0.034,0.021) 0.640
|
-0.010(-0.036,0.015) 0.426
|
-0.020(-0.045,0.005) 0.122
|
|
Non-Hispanic White
|
-0.024(-0.042,-0.006) 0.011
|
-0.021(-0.038,-0.004) 0.013
|
-0.010(-0.025,0.006) 0.212
|
|
Non-Hispanic Black
|
-0.026(-0.040,-0.011) <0.001
|
-0.018(-0.032,-0.004) 0.009
|
-0.004(-0.017,0.009) 0.516
|
|
Other Race - Including Multi-Racial
|
-0.017(-0.070,0.037) 0.539
|
-0.007(-0.055,0.040 )0.761
|
0.011(-0.039,0.061) 0.655
|
Model 1 no covariates were adjusted.
Model 2 Age, Gender (male, female), and Race (Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, Other Race - Including Multi-Racial) were adjusted.
Model 3 Age, Gender (male, female), Race (Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, Other Race - Including Multi-Racial), Poverty income ratio, BMI (<18.5,18.5-24,24-28,≥28), Waist, White blood cell count, Red blood cell count, Platelet count, hemoglobin, Serum albumin, Blood urea nitrogen, Serum uric acid ,Serum phosphorus, Serum calcium, Serum iron were adjusted.
Subgroup analysis stratified by gender: Model does not contain gender
Subgroup analysis stratified by race:Model does not contain race
Table6: Threshold effect analysis of Blood lead (ug/dl) and femur BMD in teenagers
Age, Gender (male, female), Race (Mexican American, Other Hispanic, Non-Hispanic
|
Total femur BMD
|
Femur neck BMD
|
Trochanter BMD
|
Intertrochanter BMD
|
Fitting by the standard linear model
|
-0.008 (-0.014.-0.001) 0.018
|
-0.007(-0.014,-0.001) 0.024
|
-0.007 (-0.013,-0.001) 0.020
|
-0.008(-0.016,-0.001) 0.029
|
Fitting by the two-piecewise linear model
|
|
|
|
|
Inflection point (ug/dL)
|
1.73
|
1.61
|
1.80
|
1.66
|
Blood lead < Inflection point (ug/dL)
|
-0.026(-0.039.-0.013) <0.001
|
-0.022 (-0.035,-0.009) 0.001
|
-0.018(-0.029,-0.006) 0.003
|
-0.033(-0.048.-0.018) <0.001
|
Blood lead > Inflection point (ug/dL)
|
0.004(-0.006,0.014) 0.4202
|
0.001(-0.008,0.010)0.806
|
0.000 (-0.009,0.010) 0.952
|
0.007(-0.004.0.018) 0.215
|
p for log-likelihood ratio
|
0.001
|
0.014
|
0.037
|
<0.001
|
White, Non-Hispanic Black, Other Race - Including Multi-Racial), Poverty income ratio, BMI (<18.5,18.5-24,24-28,≥28), Waist, White blood cell count, Red blood cell count, Platelet count, hemoglobin, Serum albumin, Blood urea nitrogen, Serum uric acid ,Serum phosphorus, Serum calcium, Serum iron were adjusted.
BMD: Bone mineral density
Table7: Threshold effect analysis of Blood lead (ug/dl) and femur BMD in teenagers Subgroup analysis stratified by gender.
Age, Race (Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, Other Race - Including Multi-Racial), Poverty income ratio, BMI (<18.5,18.5-24,24-28,≥28), Waist, White blood cell count, Red blood cell count, Platelet count, hemoglobin, Serum albumin, Blood urea nitrogen, Serum uric acid ,Serum phosphorus, Serum calcium, Serum iron were adjusted.
BMD: Bone mineral density