Childhood Blood Level Analysis Using Full SAMPADA Data

Author

Sinthanai Selvan Palanisamy

Part 1. Descriptives of Blood Lead Levels

The following shows the descriptives of blood lead levels We removed blood levels of 4 to 6 µg/dL for risk factor analysis as this is the range where there is uncertainty in the measurement of blood lead levels.

Blood Pb Levels (mg/dL)
Blood Pb Levels (mg/dL) with 4-6 removed
Blood Pb Levels (mg/dL) N = 4,999 N = 4,014
Blood Pb Levels (ug/dL) 4.5 (3.8), 3.4 (2.3, 5.4), 0.2, 42.5 4.4 (4.2), 2.9 (2.1, 6.1), 0.2, 42.5
bloodpblevelsmgdl_5cat
<4 2,975 (59.51%) 2,975 (74.12%)
4-6 985 (19.70%) 0 (0.00%)
6-10 697 (13.94%) 697 (17.36%)
10-20 286 (5.72%) 286 (7.13%)
>20 56 (1.12%) 56 (1.40%)
1 Mean (SD), Median (Q1, Q3), Min, Max; n (%)

Map of the distribution of blood lead levels by district: This shows the average blood lead levels in each district, with darker colors indicating higher levels. Districts with mean BLL >6 are labelled.

Figure 1: districtmap

Map of the distribution of blood lead levels by PSU: This map shows the average blood lead levels in each PSU, with darker colors indicating higher levels. From each PSU, roughly 1 to 3 samples were randomly selected for blood lead level testing. PSUs with mean BLL >20 are labelled.

Figure 2: psumap

Major findings from the descriptive analysis of blood lead levels

Prevalence of high blood lead levels (>6 µg/dL) is 22.6% in the whole sample and 28.6% in the sample with blood lead levels of 4 to 6 µg/dL removed.

There is a wide variation in blood lead levels across districts and PSUs, with some districts and PSUs having much higher average blood lead levels than others. It is possible that risk factors are not common across India but likely highly contextual and dependent on regional factors. Possible stratified analysis by region may be required if numbers are adequate.

Overaching guidance for analysis

The diagram below captures the overarching hypothesis for high blood levels and guides the further risk factor analysis

Figure 3: overarching_analysis_plan

Part 2. Bivariate analysis of blood lead levels with all SAMPADA variables

We removed blood levels of 4 to 6 µg/dL for risk factor analysis for all the below results

A. Demographic

Note: Other religion types: Buddhist, Sikh, Jain, Sindhi, Indigenous, Uraon, etc.

Blood Pb Levels (ug/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >=6)
Characteristic Mean (SD) N Mean Difference 95% CI p-value Overall
N = 4,014
<4
N = 2,975
>=6
N = 1,039
p-value PR 95% CI p-value
PSU Type 4014 0.113
Rural 4.4 (4.2) 2,680 (100.0%) 2,007 (74.9%) 673 (25.1%)
Urban 4.5 (4.2) 0.07 -0.21, 0.35 0.622 1,334 (100.0%) 968 (72.6%) 366 (27.4%) 1.09 0.98, 1.22 0.112
Gender 4014 0.008
Female 4.2 (4.1) 1,923 (100.0%) 1,462 (76.0%) 461 (24.0%)
Male 4.6 (4.3) 0.38 0.12, 0.64 0.004 2,091 (100.0%) 1,513 (72.4%) 578 (27.6%) 1.15 1.04, 1.28 0.008
Age Group 4000 0.124
0-2 4.8 (4.7) 625 (100.0%) 440 (70.4%) 185 (29.6%)
2-3 4.3 (3.8) -0.54 -0.96, -0.12 0.012 973 (100.0%) 726 (74.6%) 247 (25.4%) 0.86 0.73, 1.01 0.063
3-4 4.5 (4.3) -0.32 -0.73, 0.09 0.128 1,114 (100.0%) 829 (74.4%) 285 (25.6%) 0.86 0.74, 1.01 0.069
4-5 4.3 (4.1) -0.47 -0.88, -0.07 0.021 1,288 (100.0%) 971 (75.4%) 317 (24.6%) 0.83 0.71, 0.97 0.019
Community 4014 <0.001
Other Caste 3.9 (3.5) 826 (100.0%) 650 (78.7%) 176 (21.3%)
SC 4.7 (4.2) 0.81 0.41, 1.21 <0.001 844 (100.0%) 596 (70.6%) 248 (29.4%) 1.38 1.17, 1.63 <0.001
ST 3.6 (3.4) -0.33 -0.71, 0.06 0.097 991 (100.0%) 834 (84.2%) 157 (15.8%) 0.74 0.61, 0.90 0.003
OBC 5.3 (5.0) 1.42 1.05, 1.78 <0.001 1,274 (100.0%) 837 (65.7%) 437 (34.3%) 1.61 1.39, 1.88 <0.001
Not Known 3.9 (2.8) -0.03 -0.99, 0.93 0.949 79 (100.0%) 58 (73.4%) 21 (26.6%) 1.25 0.82, 1.78 0.265
Religion 4014 <0.001
Hindu 4.9 (4.6) 2,877 (100.0%) 1,987 (69.1%) 890 (30.9%)
Muslim 3.5 (3.4) -1.45 -1.87, -1.03 <0.001 434 (100.0%) 366 (84.3%) 68 (15.7%) 0.51 0.40, 0.63 <0.001
Christian 3.1 (2.4) -1.80 -2.18, -1.43 <0.001 573 (100.0%) 507 (88.5%) 66 (11.5%) 0.37 0.29, 0.47 <0.001
Others 3.2 (2.8) -1.72 -2.45, -0.99 <0.001 130 (100.0%) 115 (88.5%) 15 (11.5%) 0.37 0.22, 0.58 <0.001
1 Blood Pb Levels (ug/dL): Mean (SD)
2 n (%)
3 Pearson's Chi-squared test

Findings: Urban residence, male, younger age, scheduled community, OBC, Hindu religion. These are non-modifiable and possibly point to distal determinants rather than actual causes.

B. Household characteristics

Note: Other house ownership types: begar, quarters, encroached, landless, relatives, etc. Other Latrine types: Community latrine, present at home and not using, dry toilet, katcha, compost, no toilet, etc. Other cooking fuel types: cow dung, solar, biogas, electricity, kerosene, coal, weed, other, multiple types, etc. Other cooking/drinking water types: hand pump, rainwater, metro, tube well, share water, public tap, protected well, pipeline, chara, etc. Other water purification types: solar disinfection, let it stand, water filter, etc.

Blood Pb Levels (ug/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >=6)
Characteristic Mean (SD) N Mean Difference 95% CI p-value Overall
N = 4,014
<4
N = 2,975
>=6
N = 1,039
p-value PR 95% CI p-value
Type of Family 4000 0.048
Extended 4.1 (3.8) 534 (100.0%) 418 (78.3%) 116 (21.7%)
Joint 4.4 (4.4) 0.40 -0.06, 0.85 0.087 880 (100.0%) 655 (74.4%) 225 (25.6%) 1.18 0.97, 1.44 0.104
Nuclear 4.5 (4.2) 0.46 0.06, 0.85 0.023 2,586 (100.0%) 1,892 (73.2%) 694 (26.8%) 1.24 1.04, 1.48 0.017
Ownership of House 3986 0.753
Own House 4.4 (4.3) 3,456 (100.0%) 2,560 (74.1%) 896 (25.9%)
Rented house/Other 4.3 (3.6) -0.13 -0.52, 0.25 0.503 530 (100.0%) 396 (74.7%) 134 (25.3%) 0.98 0.83, 1.14 0.754
Type of House 3998 0.206
Kutcha 4.8 (4.6) 561 (100.0%) 410 (73.1%) 151 (26.9%)
Pucca 4.3 (4.2) -0.47 -0.86, -0.09 0.017 2,437 (100.0%) 1,831 (75.1%) 606 (24.9%) 0.92 0.80, 1.08 0.310
Semi-pucca 4.5 (4.1) -0.26 -0.70, 0.17 0.237 1,000 (100.0%) 724 (72.4%) 276 (27.6%) 1.03 0.87, 1.22 0.772
Number of Rooms 3989 <0.001
No/1 rooms 5.6 (4.5) 348 (100.0%) 206 (59.2%) 142 (40.8%)
2 4.8 (4.4) -0.87 -1.38, -0.36 <0.001 990 (100.0%) 693 (70.0%) 297 (30.0%) 0.74 0.63, 0.86 <0.001
3 4.5 (4.4) -1.15 -1.65, -0.64 <0.001 1,127 (100.0%) 830 (73.6%) 297 (26.4%) 0.65 0.55, 0.76 <0.001
More than 3 3.9 (3.9) -1.75 -2.24, -1.27 <0.001 1,524 (100.0%) 1,227 (80.5%) 297 (19.5%) 0.48 0.41, 0.56 <0.001
Separate Kitchen 3997 0.005
Yes 4.3 (4.1) 2,874 (100.0%) 2,165 (75.3%) 709 (24.7%)
No 4.8 (4.5) 0.52 0.23, 0.81 <0.001 1,123 (100.0%) 797 (71.0%) 326 (29.0%) 1.18 1.05, 1.31 0.004
Cooking Fuel 4014 0.009
Firewood 4.7 (4.5) 1,121 (100.0%) 812 (72.4%) 309 (27.6%)
LPG 4.3 (4.0) -0.47 -0.77, -0.18 0.001 2,818 (100.0%) 2,117 (75.1%) 701 (24.9%) 0.90 0.81, 1.01 0.079
Others 6.0 (5.4) 1.24 0.26, 2.23 0.013 75 (100.0%) 46 (61.3%) 29 (38.7%) 1.40 1.01, 1.85 0.027
Drinking Water Source 4014 0.182
Bore well 4.7 (4.7) 974 (100.0%) 710 (72.9%) 264 (27.1%)
Others 4.3 (4.2) -0.36 -0.80, 0.07 0.103 577 (100.0%) 437 (75.7%) 140 (24.3%) 0.90 0.75, 1.07 0.221
RO/Bottled water 4.5 (3.9) -0.25 -0.69, 0.19 0.267 564 (100.0%) 402 (71.3%) 162 (28.7%) 1.06 0.90, 1.25 0.493
Tap water/Water tanker 4.3 (4.0) -0.40 -0.73, -0.07 0.016 1,899 (100.0%) 1,426 (75.1%) 473 (24.9%) 0.92 0.81, 1.05 0.200
Water Used for Cooking 4014 0.057
Bore well 4.7 (4.7) 989 (100.0%) 720 (72.8%) 269 (27.2%)
Others 4.4 (4.3) -0.31 -0.74, 0.12 0.157 596 (100.0%) 449 (75.3%) 147 (24.7%) 0.91 0.76, 1.08 0.269
RO/Bottled water 4.7 (3.9) 0.03 -0.54, 0.59 0.927 277 (100.0%) 189 (68.2%) 88 (31.8%) 1.17 0.95, 1.42 0.129
Tap water/Water tanker 4.3 (4.0) -0.43 -0.74, -0.11 0.009 2,152 (100.0%) 1,617 (75.1%) 535 (24.9%) 0.91 0.81, 1.04 0.161
Water Purification Method 4014 <0.001
Add bleach/chlorine tablets 6.6 (5.3) 26 (100.0%) 13 (50.0%) 13 (50.0%)
Boiling 3.5 (2.9) -3.08 -4.70, -1.46 <0.001 793 (100.0%) 651 (82.1%) 142 (17.9%) 0.36 0.25, 0.58 <0.001
None 5.0 (4.8) -1.55 -3.15, 0.06 0.059 2,135 (100.0%) 1,462 (68.5%) 673 (31.5%) 0.63 0.46, 1.01 0.020
Others/Multiple 3.7 (3.2) -2.87 -4.51, -1.22 <0.001 416 (100.0%) 345 (82.9%) 71 (17.1%) 0.34 0.23, 0.56 <0.001
Strain through a cloth 5.0 (4.3) -1.63 -3.30, 0.05 0.058 246 (100.0%) 163 (66.3%) 83 (33.7%) 0.67 0.47, 1.10 0.068
Water filter/E. purifier 3.4 (3.5) -3.22 -4.87, -1.57 <0.001 398 (100.0%) 341 (85.7%) 57 (14.3%) 0.29 0.19, 0.48 <0.001
Latrine Type 4014 <0.001
Open Defecation 6.0 (5.3) 336 (100.0%) 202 (60.1%) 134 (39.9%)
Others 3.7 (3.0) -2.27 -3.02, -1.51 <0.001 184 (100.0%) 146 (79.3%) 38 (20.7%) 0.52 0.37, 0.70 <0.001
Present and using 4.3 (4.1) -1.69 -2.15, -1.22 <0.001 3,494 (100.0%) 2,627 (75.2%) 867 (24.8%) 0.62 0.54, 0.72 <0.001
1 Blood Pb Levels (ug/dL): Mean (SD)
2 n (%)
3 Pearson's Chi-squared test

Findings: Nuclear family, small houses, no separate kitchen, water from Borewell, inadequate or improper and Bleach/ chlorine water purification, and open defecation were all associated with high blood lead. We get some indication that water with lead contamination may be a source via ingestion. This needs to explored further in the case-control data where water has been tested for lead contamination. However, we would not know water from which source was tested.

C. Household Assets

Blood Pb Levels (ug/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >=6)
Characteristic Mean (SD) N Mean Difference 95% CI p-value Overall
N = 4,014
<4
N = 2,975
>=6
N = 1,039
p-value PR 95% CI p-value
Electricity Available 3998 >0.999
No 4.0 (3.4) 16 (100.0%) 12 (75.0%) 4 (25.0%)
Yes 4.4 (4.2) 0.43 -1.64, 2.51 0.682 3,982 (100.0%) 2,951 (74.1%) 1,031 (25.9%) 1.04 0.53, 3.04 0.936
Electric Fan 4000 0.004
No 4.0 (4.1) 483 (100.0%) 384 (79.5%) 99 (20.5%)
Yes 4.5 (4.2) 0.52 0.12, 0.92 0.011 3,517 (100.0%) 2,581 (73.4%) 936 (26.6%) 1.30 1.09, 1.57 0.005
Black and White Television 4000 0.016
No 4.4 (4.2) 3,739 (100.0%) 2,788 (74.6%) 951 (25.4%)
Yes 4.9 (4.4) 0.55 0.02, 1.08 0.041 261 (100.0%) 177 (67.8%) 84 (32.2%) 1.27 1.04, 1.51 0.012
Colour Television 4000 0.069
No 4.8 (4.9) 1,266 (100.0%) 915 (72.3%) 351 (27.7%)
Yes 4.2 (3.9) -0.59 -0.88, -0.31 <0.001 2,734 (100.0%) 2,050 (75.0%) 684 (25.0%) 0.90 0.81, 1.01 0.067
Radio/Transistor 4000 0.027
No 4.5 (4.3) 3,702 (100.0%) 2,728 (73.7%) 974 (26.3%)
Yes 3.6 (3.0) -0.85 -1.35, -0.36 <0.001 298 (100.0%) 237 (79.5%) 61 (20.5%) 0.78 0.61, 0.97 0.033
Pressure Cooker 4000 <0.001
No 5.6 (5.3) 847 (100.0%) 546 (64.5%) 301 (35.5%)
Yes 4.1 (3.8) -1.42 -1.74, -1.11 <0.001 3,153 (100.0%) 2,419 (76.7%) 734 (23.3%) 0.66 0.59, 0.73 <0.001
Cot/Bed 4000 <0.001
No 5.1 (4.6) 532 (100.0%) 350 (65.8%) 182 (34.2%)
Yes 4.3 (4.1) -0.79 -1.18, -0.41 <0.001 3,468 (100.0%) 2,615 (75.4%) 853 (24.6%) 0.72 0.63, 0.82 <0.001
Mattress 4000 <0.001
No 5.8 (5.2) 935 (100.0%) 570 (61.0%) 365 (39.0%)
Yes 4.0 (3.8) -1.75 -2.06, -1.45 <0.001 3,065 (100.0%) 2,395 (78.1%) 670 (21.9%) 0.56 0.50, 0.62 <0.001
Chair 4000 <0.001
No 4.9 (4.4) 429 (100.0%) 287 (66.9%) 142 (33.1%)
Yes 4.4 (4.2) -0.53 -0.95, -0.11 0.014 3,571 (100.0%) 2,678 (75.0%) 893 (25.0%) 0.76 0.66, 0.88 <0.001
Table 4000 <0.001
No 5.2 (4.8) 1,121 (100.0%) 745 (66.5%) 376 (33.5%)
Yes 4.1 (3.9) -1.05 -1.34, -0.77 <0.001 2,879 (100.0%) 2,220 (77.1%) 659 (22.9%) 0.68 0.61, 0.76 <0.001
Mobile Phone 4000 0.104
No 4.8 (4.2) 198 (100.0%) 137 (69.2%) 61 (30.8%)
Yes 4.4 (4.2) -0.34 -0.94, 0.27 0.275 3,802 (100.0%) 2,828 (74.4%) 974 (25.6%) 0.83 0.68, 1.05 0.094
Landline Phone 4000 0.065
No 4.4 (4.2) 3,886 (100.0%) 2,872 (73.9%) 1,014 (26.1%)
Yes 3.9 (3.6) -0.57 -1.35, 0.22 0.158 114 (100.0%) 93 (81.6%) 21 (18.4%) 0.71 0.46, 1.01 0.080
Watch/Clock 3971 0.008
No 4.7 (4.4) 1,176 (100.0%) 838 (71.3%) 338 (28.7%)
Yes 4.3 (4.1) -0.32 -0.61, -0.03 0.028 2,795 (100.0%) 2,104 (75.3%) 691 (24.7%) 0.86 0.77, 0.96 0.008
Washing Machine 4000 <0.001
No 4.7 (4.3) 2,805 (100.0%) 2,004 (71.4%) 801 (28.6%)
Yes 3.9 (3.9) -0.79 -1.08, -0.51 <0.001 1,195 (100.0%) 961 (80.4%) 234 (19.6%) 0.69 0.60, 0.78 <0.001
Refrigerator 4000 <0.001
No 4.8 (4.5) 1,954 (100.0%) 1,370 (70.1%) 584 (29.9%)
Yes 4.0 (3.9) -0.80 -1.06, -0.54 <0.001 2,046 (100.0%) 1,595 (78.0%) 451 (22.0%) 0.74 0.66, 0.82 <0.001
Computer 4000 0.001
No 4.5 (4.3) 3,711 (100.0%) 2,728 (73.5%) 983 (26.5%)
Yes 3.7 (3.7) -0.74 -1.25, -0.24 0.004 289 (100.0%) 237 (82.0%) 52 (18.0%) 0.68 0.52, 0.86 0.003
Internet 4000 <0.001
No 4.7 (4.5) 1,815 (100.0%) 1,288 (71.0%) 527 (29.0%)
Yes 4.2 (4.0) -0.48 -0.74, -0.21 <0.001 2,185 (100.0%) 1,677 (76.8%) 508 (23.2%) 0.80 0.72, 0.89 <0.001
Sewing Machine 4000 0.566
No 4.4 (4.2) 3,363 (100.0%) 2,487 (74.0%) 876 (26.0%)
Yes 4.4 (4.1) -0.07 -0.43, 0.28 0.682 637 (100.0%) 478 (75.0%) 159 (25.0%) 0.96 0.82, 1.10 0.568
Air Conditioner/Cooler 4000 0.219
No 4.4 (4.2) 3,334 (100.0%) 2,484 (74.5%) 850 (25.5%)
Yes 4.7 (4.5) 0.31 -0.04, 0.66 0.081 666 (100.0%) 481 (72.2%) 185 (27.8%) 1.09 0.95, 1.24 0.215
Bicycle 4000 0.527
No 4.4 (4.0) 2,660 (100.0%) 1,980 (74.4%) 680 (25.6%)
Yes 4.6 (4.6) 0.20 -0.08, 0.47 0.167 1,340 (100.0%) 985 (73.5%) 355 (26.5%) 1.04 0.93, 1.16 0.526
Motorcycle/Scooter 4000 0.041
No 4.4 (4.3) 1,891 (100.0%) 1,430 (75.6%) 461 (24.4%)
Yes 4.5 (4.1) 0.14 -0.12, 0.41 0.284 2,109 (100.0%) 1,535 (72.8%) 574 (27.2%) 1.12 1.00, 1.24 0.041
Car/Four Wheeler 4000 <0.001
No 4.6 (4.3) 3,473 (100.0%) 2,521 (72.6%) 952 (27.4%)
Yes 3.5 (3.4) -1.12 -1.50, -0.73 <0.001 527 (100.0%) 444 (84.3%) 83 (15.7%) 0.57 0.46, 0.70 <0.001
Animal Drawn Cart 4000 0.115
No 4.5 (4.3) 3,801 (100.0%) 2,808 (73.9%) 993 (26.1%)
Yes 3.9 (3.3) -0.55 -1.15, 0.05 0.075 199 (100.0%) 157 (78.9%) 42 (21.1%) 0.81 0.60, 1.04 0.127
Water Pump 4000 0.216
No 4.5 (4.2) 3,416 (100.0%) 2,520 (73.8%) 896 (26.2%)
Yes 4.3 (4.5) -0.17 -0.54, 0.20 0.379 584 (100.0%) 445 (76.2%) 139 (23.8%) 0.91 0.77, 1.06 0.221
Tractor 4000 0.220
No 4.4 (4.2) 3,883 (100.0%) 2,884 (74.3%) 999 (25.7%)
Yes 4.8 (4.7) 0.34 -0.44, 1.11 0.395 117 (100.0%) 81 (69.2%) 36 (30.8%) 1.20 0.89, 1.54 0.205
Thresher/Seed Removal Machine 4000 0.779
No 4.4 (4.2) 3,953 (100.0%) 2,931 (74.1%) 1,022 (25.9%)
Yes 4.6 (4.8) 0.17 -1.04, 1.39 0.781 47 (100.0%) 34 (72.3%) 13 (27.7%) 1.07 0.63, 1.61 0.776
Home Theatre 4000 0.921
No 4.4 (4.2) 3,905 (100.0%) 2,895 (74.1%) 1,010 (25.9%)
Yes 4.1 (3.1) -0.34 -1.20, 0.52 0.440 95 (100.0%) 70 (73.7%) 25 (26.3%) 1.02 0.70, 1.39 0.921
Vacuum Cleaner 4000 0.049
No 4.5 (4.2) 3,925 (100.0%) 2,902 (73.9%) 1,023 (26.1%)
Yes 3.0 (2.6) -1.46 -2.43, -0.50 0.003 75 (100.0%) 63 (84.0%) 12 (16.0%) 0.61 0.34, 0.98 0.067
Microwave/Electric Oven 4000 <0.001
No 4.5 (4.2) 3,872 (100.0%) 2,850 (73.6%) 1,022 (26.4%)
Yes 2.9 (3.2) -1.59 -2.33, -0.85 <0.001 128 (100.0%) 115 (89.8%) 13 (10.2%) 0.38 0.22, 0.61 <0.001
Treadmill/Exercise Equipment 4000 0.434
No 4.4 (4.2) 3,979 (100.0%) 2,951 (74.2%) 1,028 (25.8%)
Yes 4.0 (2.6) -0.48 -2.29, 1.33 0.604 21 (100.0%) 14 (66.7%) 7 (33.3%) 1.29 0.62, 2.12 0.411
Type of PDS/Ration Card 3996 <0.001
AAY(Antyodaya Anna Yojana) 3.0 (2.2) 191 (100.0%) 170 (89.0%) 21 (11.0%)
APL(Above Poverty Line) 4.0 (4.2) 1.02 0.36, 1.67 0.002 902 (100.0%) 708 (78.5%) 194 (21.5%) 1.96 1.32, 3.08 0.002
BPL(Below Poverty Line) 4.5 (4.1) 1.53 0.91, 2.16 <0.001 1,976 (100.0%) 1,419 (71.8%) 557 (28.2%) 2.56 1.76, 4.00 <0.001
No Card 4.6 (4.1) 1.61 0.94, 2.28 <0.001 737 (100.0%) 543 (73.7%) 194 (26.3%) 2.39 1.62, 3.77 <0.001
TPDS(Targetted PDS) 6.0 (6.3) 2.99 2.14, 3.83 <0.001 190 (100.0%) 121 (63.7%) 69 (36.3%) 3.30 2.16, 5.31 <0.001
Any Woman Enrolled in a Self-Help Group 3978 0.074
No 4.3 (4.2) 2,821 (100.0%) 2,113 (74.9%) 708 (25.1%)
Yes 4.7 (4.4) 0.30 0.02, 0.59 0.039 1,157 (100.0%) 835 (72.2%) 322 (27.8%) 1.11 0.99, 1.24 0.072
Any Household Member Beneficiary Under MGNREGA 3994 0.948
No 4.4 (4.1) 2,985 (100.0%) 2,213 (74.1%) 772 (25.9%)
Yes 4.6 (4.6) 0.21 -0.09, 0.52 0.163 1,009 (100.0%) 747 (74.0%) 262 (26.0%) 1.00 0.89, 1.13 0.948
Household Covered by Insurance 3997 0.002
No 4.6 (4.2) 1,888 (100.0%) 1,358 (71.9%) 530 (28.1%)
Yes 4.3 (4.3) -0.32 -0.58, -0.05 0.019 2,109 (100.0%) 1,606 (76.1%) 503 (23.9%) 0.85 0.76, 0.94 0.002
Owns Agriculture Land 3925 <0.001
No 4.2 (4.0) 2,837 (100.0%) 2,162 (76.2%) 675 (23.8%)
Yes 4.9 (4.6) 0.66 0.37, 0.95 <0.001 1,088 (100.0%) 752 (69.1%) 336 (30.9%) 1.30 1.16, 1.45 <0.001
Owns Livestock 3873 0.026
No 4.3 (4.0) 2,983 (100.0%) 2,239 (75.1%) 744 (24.9%)
Yes 4.8 (4.9) 0.50 0.18, 0.81 0.002 890 (100.0%) 635 (71.3%) 255 (28.7%) 1.15 1.02, 1.29 0.025
Cows/Bulls/Buffaloes/Yaks 819 0.382
No 4.8 (5.3) 165 (100.0%) 122 (73.9%) 43 (26.1%)
Yes 4.9 (4.9) 0.09 -0.76, 0.94 0.840 654 (100.0%) 461 (70.5%) 193 (29.5%) 1.13 0.87, 1.53 0.389
Camels 638 >0.999
No 4.6 (4.7) 635 (100.0%) 469 (73.9%) 166 (26.1%)
Yes 4.3 (2.2) -0.26 -5.58, 5.06 0.924 3 (100.0%) 2 (66.7%) 1 (33.3%) 1.28 0.26, 6.35 0.767
Horses/Donkeys/Mules 634 >0.999
No 4.6 (4.7) 631 (100.0%) 466 (73.9%) 165 (26.1%)
Yes 4.9 (2.9) 0.29 -5.02, 5.60 0.915 3 (100.0%) 2 (66.7%) 1 (33.3%) 1.27 0.26, 6.35 0.767
Goats/Sheeps 728 0.022
No 4.3 (4.2) 419 (100.0%) 317 (75.7%) 102 (24.3%)
Yes 5.2 (5.3) 0.84 0.15, 1.53 0.017 309 (100.0%) 210 (68.0%) 99 (32.0%) 1.32 1.04, 1.66 0.022
Pigs 646 0.090
No 4.7 (4.8) 570 (100.0%) 413 (72.5%) 157 (27.5%)
Yes 4.1 (4.8) -0.60 -1.75, 0.54 0.302 76 (100.0%) 62 (81.6%) 14 (18.4%) 0.67 0.39, 1.04 0.109
Chickens/Ducks 714 0.037
No 4.8 (4.6) 422 (100.0%) 297 (70.4%) 125 (29.6%)
Yes 4.4 (5.1) -0.38 -1.10, 0.34 0.296 292 (100.0%) 226 (77.4%) 66 (22.6%) 0.76 0.59, 0.98 0.040
Wealth Index 4014 <0.001
Higher 4.3 (4.0) 818 (100.0%) 620 (75.8%) 198 (24.2%)
Highest 3.9 (3.9) -0.41 -0.81, -0.01 0.047 857 (100.0%) 691 (80.6%) 166 (19.4%) 0.80 0.67, 0.96 0.017
Lower 4.4 (4.0) 0.13 -0.28, 0.54 0.532 808 (100.0%) 585 (72.4%) 223 (27.6%) 1.14 0.97, 1.35 0.119
Lowest 5.7 (5.3) 1.42 1.01, 1.83 <0.001 751 (100.0%) 476 (63.4%) 275 (36.6%) 1.51 1.30, 1.77 <0.001
Middle 4.1 (3.4) -0.22 -0.63, 0.19 0.301 780 (100.0%) 603 (77.3%) 177 (22.7%) 0.94 0.78, 1.12 0.476
1 Blood Pb Levels (ug/dL): Mean (SD)
2 n (%)
3 Fisher's exact test; Pearson's Chi-squared test

Findings: Largely ownership of assets is associated with lower blood lead levels, except for a few such as agricultural land and livestock. This needs to be explored further in the future case-control data where livestock and feed/water may be additionally tested for lead contamination. There is a clear dose-response type relationship between wealth index and blood lead levels, with lower income being associated with higher blood lead levels. This may be due to poorer living conditions, lack of access to cleaner water, and higher exposure to lead-containing products among lower-income households.

C1. Household income

C2. Agricultural land ownership

D. Blood micro-nutrient levels

Blood Pb Levels (ug/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >=6)
Characteristic Mean (SD) N Mean Difference 95% CI p-value Overall
N = 4,014
<4
N = 2,975
>=6
N = 1,039
p-value PR 95% CI p-value
Anaemia 3780 <0.001
Anemia 4.9 (4.7) 1,321 (100.0%) 923 (69.9%) 398 (30.1%)
No Anemia 4.3 (4.0) -0.62 -0.91, -0.34 <0.001 2,459 (100.0%) 1,849 (75.2%) 610 (24.8%) 0.82 0.74, 0.92 <0.001
Anaemia Status (Any, New) 3780 <0.001
No Anemia 4.3 (4.0) 2,459 (100.0%) 1,849 (75.2%) 610 (24.8%)
Mild Anemia 4.8 (4.6) 0.48 0.13, 0.82 0.007 766 (100.0%) 548 (71.5%) 218 (28.5%) 1.15 1.00, 1.31 0.041
Moder+Sev Anemia 5.1 (4.7) 0.82 0.43, 1.21 <0.001 555 (100.0%) 375 (67.6%) 180 (32.4%) 1.31 1.13, 1.50 <0.001
Anemia adjust Iron 906 0.001
No Anemia + No Iron Deficiency 4.0 (3.8) 568 (100.0%) 447 (78.7%) 121 (21.3%)
No Anemia + Iron Deficiency 6.3 (6.2) 2.28 1.17, 3.40 <0.001 51 (100.0%) 30 (58.8%) 21 (41.2%) 1.93 1.29, 2.70 <0.001
Anemia + No Iron Deficiency 3.7 (3.0) -0.35 -1.02, 0.32 0.305 169 (100.0%) 136 (80.5%) 33 (19.5%) 0.92 0.64, 1.27 0.620
Anemia + Iron Deficiency 4.9 (4.3) 0.87 0.10, 1.64 0.028 118 (100.0%) 81 (68.6%) 37 (31.4%) 1.47 1.06, 1.98 0.015
Iron Deficiency Status 968 <0.001
No Iron Deficiency 3.9 (3.5) 787 (100.0%) 627 (79.7%) 160 (20.3%)
Iron Deficiency (ID) 5.3 (4.8) 1.39 0.78, 2.01 <0.001 181 (100.0%) 119 (65.7%) 62 (34.3%) 1.68 1.31, 2.14 <0.001
Vitamin B12 Status 887 0.739
Deficient (<203 pg/mL) 4.3 (4.3) 314 (100.0%) 238 (75.8%) 76 (24.2%)
Normal (>=203 pg/mL) 4.2 (3.7) -0.16 -0.71, 0.38 0.559 573 (100.0%) 440 (76.8%) 133 (23.2%) 0.96 0.75, 1.23 0.739
Serum Folate Status 887 0.484
Deficient (<4 ng/mL) 4.0 (3.8) 115 (100.0%) 91 (79.1%) 24 (20.9%)
Normal (>=4 ng/mL) 4.2 (4.0) 0.25 -0.53, 1.02 0.530 772 (100.0%) 588 (76.2%) 184 (23.8%) 1.14 0.80, 1.72 0.490
Vitamin D Status 884 0.069
Deficient (<12 ng/mL) 4.7 (5.1) 142 (100.0%) 100 (70.4%) 42 (29.6%)
Normal (>=12 ng/mL) 4.1 (3.7) -0.56 -1.27, 0.15 0.121 742 (100.0%) 575 (77.5%) 167 (22.5%) 0.76 0.58, 1.03 0.062
1 Blood Pb Levels (ug/dL): Mean (SD)
2 n (%)
3 Pearson's Chi-squared test
Correlation between Blood micronutrient and Blood Pb levels
Micronutrient Correlation Coefficient (r) P-value
Serum Ferritin (ug/L) -0.091 0.0048
Log Ferritin (ug/L) -0.188 0.0000
RBC Folate (ng/mL) -0.037 0.3050
Serum Folate (ng/mL) -0.045 0.1774
Log Serum Folate (ng/mL) -0.011 0.7481
Vitamin B12 (pg/mL) -0.046 0.1745
Log Vitamin B12 (pg/mL) -0.074 0.0268
Vitamin D (ng/mL) -0.046 0.1737
Log Vitamin D (ng/mL) -0.055 0.1013

Findings: Anemia and iron deficiency are clearly associated with higher blood lead levels. This supports our hypothesis that this leads to increased absorption of lead in the gut. But it is also possible that lead exposure contributes to these deficiencies. In addition, the continuous variables of blood levels of ferritin and vitamin B12 have a weak negative correlation with blood lead but others like folate and vitamin D are not associated.

These indicators of longer term nutritional status and micronutrient deficiency are more relevant for lead absorption. In simple words, lower intake of micronutrients in diet over a longer period leads to lower blood levels of these micronutrients which in turn leads to higher absorption of lead in the gut and higher blood lead levels.

E. Inflammation

Blood Pb Levels (ug/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >=6)
Characteristic Mean (SD) N Mean Difference 95% CI p-value Overall
N = 4,014
<4
N = 2,975
>=6
N = 1,039
p-value PR 95% CI p-value
CRP Status 973 0.032
No Inflammation 4.2 (3.9) 886 (100.0%) 674 (76.1%) 212 (23.9%)
Inflammation 3.2 (2.7) -1.02 -1.87, -0.17 0.019 87 (100.0%) 75 (86.2%) 12 (13.8%) 0.58 0.32, 0.94 0.045
AGP Status 971 0.238
No Inflammation 4.2 (4.0) 835 (100.0%) 637 (76.3%) 198 (23.7%)
Inflammation 3.7 (2.9) -0.53 -1.23, 0.17 0.137 136 (100.0%) 110 (80.9%) 26 (19.1%) 0.81 0.54, 1.14 0.249
Inflammation Status 972 0.074
No Inflammation 4.3 (4.0) 808 (100.0%) 613 (75.9%) 195 (24.1%)
Inflammation 3.5 (2.8) -0.76 -1.40, -0.11 0.022 164 (100.0%) 135 (82.3%) 29 (17.7%) 0.73 0.50, 1.02 0.083
1 Blood Pb Levels (ug/dL): Mean (SD)
2 n (%)
3 Pearson's Chi-squared test
Correlation between Inflammation markers and Blood Pb levels
Inflammation Marker Correlation Coefficient (r) P-value
CRP-HS (mg/L) -0.069 0.0322
Alpha-1 Acid Glycoprotein (g/L) -0.075 0.0202
Log CRP -0.085 0.0076
Log AGP -0.067 0.0377

Findings: Generally lack of inflammation is associated with higher blood lead levels. This may be because inflammation leads to sequestration of lead in the liver and other tissues, leading to lower blood lead levels. The biological plausibility of this association needs to be assessed further. Whether to use these variables to adjust for the relationship between blood micronutrients and blood lead levels needs to be assessed.

F. Anthropometric

Blood Pb Levels (ug/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >=6)
Characteristic Mean (SD) N Mean Difference 95% CI p-value Overall
N = 4,014
<4
N = 2,975
>=6
N = 1,039
p-value PR 95% CI p-value
Stunting 3205 <0.001
No Stunting 4.3 (4.0) 2,300 (100.0%) 1,722 (74.9%) 578 (25.1%)
Stunting 4.9 (4.5) 0.59 0.20, 0.97 0.003 591 (100.0%) 405 (68.5%) 186 (31.5%) 1.25 1.09, 1.43 0.001
Severe Stunting 5.8 (5.4) 1.46 0.96, 1.96 <0.001 314 (100.0%) 199 (63.4%) 115 (36.6%) 1.46 1.23, 1.70 <0.001
Wasting 3179 0.289
No Wasting 4.5 (4.2) 2,751 (100.0%) 2,009 (73.0%) 742 (27.0%)
Wasting 4.9 (4.8) 0.45 -0.04, 0.93 0.072 332 (100.0%) 231 (69.6%) 101 (30.4%) 1.13 0.94, 1.33 0.175
Severe Wasting 4.8 (3.9) 0.28 -0.59, 1.15 0.527 96 (100.0%) 66 (68.8%) 30 (31.3%) 1.16 0.83, 1.53 0.341
Under weight 3209 <0.001
No Underweight 4.3 (4.0) 2,451 (100.0%) 1,831 (74.7%) 620 (25.3%)
Underweight 5.3 (4.9) 0.98 0.59, 1.37 <0.001 557 (100.0%) 375 (67.3%) 182 (32.7%) 1.29 1.12, 1.48 <0.001
Severe Underweight 5.5 (4.8) 1.21 0.60, 1.82 <0.001 201 (100.0%) 123 (61.2%) 78 (38.8%) 1.53 1.26, 1.83 <0.001
MUAC Group 3221 <0.001
Normal 4.5 (4.3) 3,012 (100.0%) 2,208 (73.3%) 804 (26.7%)
Moderate Acute Malnutrition 5.0 (4.2) 0.51 -0.21, 1.22 0.163 145 (100.0%) 89 (61.4%) 56 (38.6%) 1.45 1.15, 1.77 <0.001
Severe Acute Malnutrition 5.0 (3.5) 0.43 -0.63, 1.49 0.427 64 (100.0%) 39 (60.9%) 25 (39.1%) 1.46 1.03, 1.93 0.017
1 Blood Pb Levels (ug/dL): Mean (SD)
2 n (%)
3 Pearson's Chi-squared test

Findings: Stunting, and underweight which are chronic malnutrition indicators are associated with higher blood lead levels. This may be because malnutrition leads to increased absorption of lead in the gut. But it is also possible that lead exposure contributes to malnutrition. The direction of causality cannot be determined from this cross-sectional analysis.

G. Dietary nutrient intake

Correlation between Nutritional Variables and Blood Pb Levels
Inflammation Marker Correlation Coefficient (r) P-value
Energy Intake (kcal/day) -0.074 0.0001
Protein Intake (g/day) -0.106 0.0000
Total Fat Intake (g/day) -0.064 0.0005
Carbohydrate Intake (g/day) -0.053 0.0039
Thiamine (B1) Intake (mg/day) -0.072 0.0001
Riboflavin (B2) Intake (mg/day) -0.085 0.0000
Niacin (B3) Intake (mg/day) -0.066 0.0003
Vitamin B6 Intake (mg/day) -0.071 0.0001
Total Folate (B9) Intake (ug/day) -0.082 0.0000
Vitamin A Intake (mg/day) -0.016 0.3859
Vitamin D Intake (mg/day) -0.016 0.3848
Vitamin C Intake (mg/day) -0.040 0.0306
Vitamin E Intake (mg/day) -0.111 0.0000
Iron Intake (mg/day) -0.077 0.0000
Zinc Intake (mg/day) -0.086 0.0000
Calcium Intake (mg/day) -0.076 0.0000
Magnesium Intake (mg/day) -0.058 0.0015
Potassium Intake (mg/day) -0.073 0.0001
Sodium Intake (mg/day) 0.011 0.5577
Logistic Regression of Nutritional Variables on Blood Pb Level Categories
Blood Parameter Odds Ratio (per 10-unit increase) 95% CI Lower 95% CI Upper P-value
Energy Intake (kcal/day) 0.996 0.994 0.998 0.0001
Protein Intake (g/day) 0.860 0.814 0.907 0.0000
Total Fat Intake (g/day) 0.933 0.890 0.975 0.0025
Carbohydrate Intake (g/day) 0.982 0.971 0.993 0.0019
Thiamine (B1) Intake (mg/day) 0.005 0.000 0.070 0.0001
Riboflavin (B2) Intake (mg/day) 0.001 0.000 0.018 0.0000
Niacin (B3) Intake (mg/day) 0.656 0.499 0.851 0.0020
Vitamin B6 Intake (mg/day) 0.007 0.001 0.082 0.0001
Total Folate (B9) Intake (ug/day) 0.971 0.958 0.984 0.0000
Vitamin A Intake (mg/day) 1.000 0.998 1.002 0.8901
Vitamin D Intake (mg/day) 1.018 0.959 1.079 0.5447
Vitamin C Intake (mg/day) 0.976 0.949 1.002 0.0744
Vitamin E Intake (mg/day) 0.043 0.013 0.134 0.0000
Iron Intake (mg/day) 0.605 0.489 0.744 0.0000
Zinc Intake (mg/day) 0.386 0.257 0.571 0.0000
Calcium Intake (mg/day) 0.993 0.989 0.997 0.0006
Magnesium Intake (mg/day) 0.987 0.978 0.995 0.0019
Potassium Intake (mg/day) 0.997 0.996 0.999 0.0001
Sodium Intake (mg/day) 1.000 1.000 1.001 0.0692

Findings: There is a weak negative correlation between intake of macro and micro- nutrients in diet and blood lead levels. We find corroborative evidence in the fact that iron deficiency and anemia also had similar association as in Part 2D. However, these are measured at a single time point and may not be the best indicators of long term nutritional status which is more relevant for lead absorption. Also, birth weight does not seem to be associated.

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H. CBC parameters

Correlation between CBC Parameters and Blood Pb Levels
CBC Parameters Correlation Coefficient (r) P-value
White Blood Cell Count (×10³/µL) 0.090 0.0000
Lymphocytes (%) 0.027 0.0918
Monocytes (%) -0.056 0.0004
Granulocytes (%) -0.008 0.5928
Lymphocytes (Absolute Count) 0.115 0.0000
Monocytes (Absolute Count) 0.005 0.7605
Granulocytes (Absolute Count) 0.046 0.0039
Red Blood Cell Count (×10⁶/µL) 0.133 0.0000
Hemoglobin (g/dL) -0.101 0.0000
Hematocrit (%) -0.034 0.0293
Mean Corpuscular Volume (fL) -0.167 0.0000
Mean Corpuscular Hemoglobin (pg) -0.135 0.0000
Mean Corpuscular Hemoglobin Concentration -0.063 0.0001
Red Cell Distribution Width - CV (%) 0.142 0.0000
Red Cell Distribution Width (SD) -0.035 0.0280
Estimated Average Glucose -0.037 0.7131
Platelet Count (×10³/µL) 0.144 0.0000
Thrombocrit 0.136 0.0000
Mean Platelet Volume (fL) -0.048 0.0022
Platelet Distribution Width -0.115 0.0000
Logistic Regression of Blood Parameters on Blood Pb Level Categories
Blood Parameter Odds Ratio (per 10-unit increase) 95% CI Lower 95% CI Upper P-value
White Blood Cell Count (×10³/µL) 1.85 1.48 2.33 0.00
Lymphocytes (%) 1.09 1.03 1.15 0.00
Monocytes (%) 0.66 0.53 0.82 0.00
Granulocytes (%) 0.96 0.90 1.01 0.12
Lymphocytes (Absolute Count) 4.60 3.12 6.81 0.00
Monocytes (Absolute Count) 1.20 0.35 3.59 0.73
Granulocytes (Absolute Count) 1.34 1.02 1.81 0.04
Red Blood Cell Count (×10⁶/µL) 75.33 23.72 243.62 0.00
Hemoglobin (g/dL) 0.26 0.16 0.40 0.00
Hematocrit (%) 0.85 0.73 0.98 0.03
Mean Corpuscular Volume (fL) 0.70 0.65 0.75 0.00
Mean Corpuscular Hemoglobin (pg) 0.45 0.38 0.54 0.00
Mean Corpuscular Hemoglobin Concentration 0.45 0.33 0.60 0.00
Red Cell Distribution Width - CV (%) 4.02 2.86 5.67 0.00
Red Cell Distribution Width (SD) 0.86 0.73 1.00 0.05
Estimated Average Glucose 0.85 0.00 22.11 0.93
Platelet Count (×10³/µL) 1.03 1.02 1.04 0.00
Thrombocrit 551918374110013.38 179342038252.54 1858315895129676544.00 0.00
Mean Platelet Volume (fL) 0.33 0.19 0.58 0.00
Platelet Distribution Width 0.49 0.41 0.60 0.00

Findings: Complete blood count parameters such as hemoglobin, hematocrit, red blood cell count, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelet count and white blood cell count are all negatively correlated with blood lead levels. These are possible consequences of high blood lead levels.

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High level causal diagram for high blood levels (Simplified)

Part 3A. Revised adjusted regression analysis for factors associated

We selected four groups of modifiable risk factors for adjusted analysis based on the literature and our unadjusted analysis: 1) drinking water source, 2) micronutrient deficiency, 3) malnutrition status, and 4) diet poor in micronutrients. We ran a separate regression model for each of the exposure variables in these groups adjusted for a set of variables based on the causal diagram shown above.

A. Drinking water source

Characteristic N OR1 95% CI p-value
Drinking Water Source 3,984


    Bore well

    Others
0.89 0.70, 1.14 0.4
    RO/Bottled water
1.42 1.10, 1.84 0.006
    Tap water/Water tanker
0.97 0.81, 1.17 0.8
Age Group 3,984


    0-2

    2-3
0.79 0.63, 0.99 0.042
    3-4
0.79 0.63, 0.98 0.035
    4-5
0.74 0.60, 0.92 0.007
Gender 3,984


    Female

    Male
1.23 1.06, 1.42 0.006
Type of House 3,984


    Kutcha

    Pucca
1.29 1.02, 1.63 0.037
    Semi-pucca
1.21 0.95, 1.55 0.13
PSU Type 3,984


    Rural

    Urban
1.27 1.08, 1.50 0.004
Wealth Index 3,984


    Higher

    Highest
0.69 0.54, 0.88 0.002
    Lower
1.36 1.08, 1.71 0.009
    Lowest
2.31 1.81, 2.95 <0.001
    Middle
1.01 0.80, 1.27
0.9
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio

B. Micronutrient deficiency

Characteristic N OR1 95% CI p-value
Iron Deficiency Status 959


    No Iron Deficiency

    Iron Deficiency (ID)
2.01 1.38, 2.92 <0.001
Age Group 959


    0-2

    2-3
1.20 0.69, 2.12 0.5
    3-4
1.22 0.73, 2.10 0.5
    4-5
1.21 0.73, 2.06 0.5
Gender 959


    Female

    Male
1.47 1.08, 2.03 0.016
Type of House 959


    Kutcha

    Pucca
1.17 0.72, 1.95 0.5
    Semi-pucca
0.87 0.51, 1.51 0.6
PSU Type 959


    Rural

    Urban
1.30 0.92, 1.82 0.13
Wealth Index 959


    Higher

    Highest
0.80 0.50, 1.29 0.4
    Lower
1.57 0.96, 2.57 0.072
    Lowest
2.10 1.26, 3.51 0.005
    Middle
0.88 0.53, 1.44 0.6
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Anaemia 3,752


    Anemia

    No Anemia
0.80 0.68, 0.93 0.004
Age Group 3,752


    0-2

    2-3
0.81 0.64, 1.03 0.088
    3-4
0.81 0.65, 1.03 0.082
    4-5
0.78 0.63, 0.98 0.035
Gender 3,752


    Female

    Male
1.24 1.07, 1.44 0.004
Type of House 3,752


    Kutcha

    Pucca
1.33 1.05, 1.69 0.020
    Semi-pucca
1.23 0.96, 1.58 0.10
PSU Type 3,752


    Rural

    Urban
1.36 1.15, 1.60 <0.001
Wealth Index 3,752


    Higher

    Highest
0.75 0.59, 0.96 0.022
    Lower
1.34 1.06, 1.70 0.014
    Lowest
2.28 1.79, 2.92 <0.001
    Middle
0.99 0.78, 1.26
0.9
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Vitamin B12 Status 878


    Deficient (<203 pg/mL)

    Normal (>=203 pg/mL)
1.06 0.76, 1.49 0.7
Age Group 878


    0-2

    2-3
1.22 0.68, 2.22 0.5
    3-4
1.09 0.63, 1.91 0.8
    4-5
1.09 0.65, 1.87 0.7
Gender 878


    Female

    Male
1.43 1.03, 1.98 0.032
Type of House 878


    Kutcha

    Pucca
1.42 0.86, 2.39 0.2
    Semi-pucca
0.95 0.55, 1.67 0.9
PSU Type 878


    Rural

    Urban
1.40 0.98, 1.98 0.061
Wealth Index 878


    Higher

    Highest
0.72 0.44, 1.17 0.2
    Lower
1.57 0.95, 2.60 0.079
    Lowest
2.26 1.33, 3.85 0.003
    Middle
0.94 0.56, 1.56 0.8
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Serum Folate Status 878


    Deficient (<4 ng/mL)

    Normal (>=4 ng/mL)
1.16 0.71, 1.94 0.6
Age Group 878


    0-2

    2-3
1.17 0.65, 2.14 0.6
    3-4
1.08 0.63, 1.89 0.8
    4-5
1.08 0.65, 1.85 0.8
Gender 878


    Female

    Male
1.41 1.02, 1.96 0.037
Type of House 878


    Kutcha

    Pucca
1.38 0.84, 2.33 0.2
    Semi-pucca
0.93 0.53, 1.63 0.8
PSU Type 878


    Rural

    Urban
1.42 1.00, 2.01 0.051
Wealth Index 878


    Higher

    Highest
0.71 0.44, 1.17 0.2
    Lower
1.56 0.94, 2.58 0.084
    Lowest
2.21 1.31, 3.76 0.003
    Middle
0.91 0.54, 1.52 0.7
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Vitamin D Status 875


    Deficient (<12 ng/mL)

    Normal (>=12 ng/mL)
0.70 0.47, 1.07 0.10
Age Group 875


    0-2

    2-3
1.21 0.67, 2.20 0.5
    3-4
1.07 0.62, 1.87 0.8
    4-5
1.07 0.64, 1.84 0.8
Gender 875


    Female

    Male
1.43 1.03, 1.98 0.032
Type of House 875


    Kutcha

    Pucca
1.43 0.87, 2.41 0.2
    Semi-pucca
0.97 0.56, 1.70
0.9
PSU Type 875


    Rural

    Urban
1.35 0.95, 1.92 0.093
Wealth Index 875


    Higher

    Highest
0.71 0.43, 1.16 0.2
    Lower
1.59 0.96, 2.64 0.071
    Lowest
2.25 1.33, 3.83 0.003
    Middle
0.94 0.56, 1.56 0.8
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Anemia adjust Iron 897


    No Anemia + No Iron Deficiency

    No Anemia + Iron Deficiency
2.32 1.23, 4.32 0.008
    Anemia + No Iron Deficiency
0.82 0.51, 1.27 0.4
    Anemia + Iron Deficiency
1.60 0.99, 2.54 0.050
Age Group 897


    0-2

    2-3
1.24 0.68, 2.30 0.5
    3-4
1.10 0.62, 1.97 0.8
    4-5
1.14 0.67, 2.02 0.6
Gender 897


    Female

    Male
1.50 1.09, 2.09 0.014
Type of House 897


    Kutcha

    Pucca
1.25 0.76, 2.11 0.4
    Semi-pucca
0.88 0.51, 1.54 0.6
PSU Type 897


    Rural

    Urban
1.30 0.92, 1.85 0.14
Wealth Index 897


    Higher

    Highest
0.84 0.52, 1.38 0.5
    Lower
1.74 1.04, 2.91 0.034
    Lowest
2.49 1.47, 4.25 <0.001
    Middle
0.90 0.53, 1.51 0.7
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio

C. Malnutrition status

Characteristic N OR1 95% CI p-value
Stunting 3,195


    No Stunting

    Stunting
1.28 1.05, 1.57 0.016
    Severe Stunting
1.47 1.13, 1.90 0.003
Age Group 3,195


    0-2

    2-3
0.73 0.57, 0.94 0.014
    3-4
0.79 0.62, 1.01 0.061
    4-5
0.74 0.58, 0.94 0.013
Gender 3,195


    Female

    Male
1.17 1.00, 1.37 0.056
Type of House 3,195


    Kutcha

    Pucca
1.45 1.12, 1.89 0.005
    Semi-pucca
1.29 0.99, 1.69 0.062
PSU Type 3,195


    Rural

    Urban
1.35 1.13, 1.61 <0.001
Wealth Index 3,195


    Higher

    Highest
0.70 0.53, 0.91 0.008
    Lower
1.33 1.03, 1.71 0.027
    Lowest
2.13 1.64, 2.78 <0.001
    Middle
0.97 0.75, 1.26 0.8
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Wasting 3,169


    No Wasting

    Wasting
1.11 0.86, 1.42 0.4
    Severe Wasting
1.13 0.71, 1.76 0.6
Age Group 3,169


    0-2

    2-3
0.72 0.56, 0.92 0.010
    3-4
0.77 0.61, 0.99 0.037
    4-5
0.70 0.55, 0.90 0.004
Gender 3,169


    Female

    Male
1.16 0.99, 1.37 0.061
Type of House 3,169


    Kutcha

    Pucca
1.44 1.11, 1.87 0.006
    Semi-pucca
1.29 0.99, 1.69 0.063
PSU Type 3,169


    Rural

    Urban
1.32 1.11, 1.57 0.002
Wealth Index 3,169


    Higher

    Highest
0.68 0.52, 0.89 0.005
    Lower
1.38 1.07, 1.78 0.012
    Lowest
2.24 1.73, 2.92 <0.001
    Middle
1.00 0.77, 1.29
0.9
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Under weight 3,199


    No Underweight

    Underweight
1.32 1.07, 1.61 0.008
    Severe Underweight
1.65 1.21, 2.23 0.001
Age Group 3,199


    0-2

    2-3
0.70 0.55, 0.90 0.006
    3-4
0.76 0.60, 0.97 0.028
    4-5
0.70 0.55, 0.89 0.003
Gender 3,199


    Female

    Male
1.17 1.00, 1.37 0.055
Type of House 3,199


    Kutcha

    Pucca
1.44 1.11, 1.87 0.006
    Semi-pucca
1.28 0.98, 1.68 0.071
PSU Type 3,199


    Rural

    Urban
1.33 1.12, 1.58 0.001
Wealth Index 3,199


    Higher

    Highest
0.70 0.53, 0.91 0.009
    Lower
1.33 1.03, 1.71 0.028
    Lowest
2.13 1.64, 2.77 <0.001
    Middle
0.98 0.76, 1.27 0.9
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
MUAC Group 3,199


    Normal

    Moderate Acute Malnutrition
1.55 1.09, 2.21 0.015
    Severe Acute Malnutrition
1.73 1.02, 2.90 0.039
Age Group 3,199


    0-2

    2-3
0.73 0.57, 0.94 0.013
    3-4
0.80 0.63, 1.03 0.078
    4-5
0.73 0.58, 0.94 0.012
Gender 3,199


    Female

    Male
1.18 1.01, 1.38 0.041
Type of House 3,199


    Kutcha

    Pucca
1.45 1.12, 1.89 0.005
    Semi-pucca
1.27 0.97, 1.66 0.084
PSU Type 3,199


    Rural

    Urban
1.31 1.10, 1.56 0.002
Wealth Index 3,199


    Higher

    Highest
0.69 0.52, 0.90 0.006
    Lower
1.36 1.06, 1.76 0.015
    Lowest
2.24 1.72, 2.91 <0.001
    Middle
0.98 0.76, 1.26 0.9
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio

D. Diet poor in micronutrients

Characteristic N OR1 95% CI p-value
Iron Intake (mg/day) 2,933 0.95 0.93, 0.97 <0.001
Age Group 2,933


    0-2

    2-3
0.85 0.64, 1.12 0.2
    3-4
0.83 0.63, 1.09 0.2
    4-5
0.79 0.60, 1.03 0.085
Gender 2,933


    Female

    Male
1.27 1.07, 1.50 0.006
Type of House 2,933


    Kutcha

    Pucca
1.47 1.12, 1.92 0.005
    Semi-pucca
1.33 1.01, 1.76 0.045
PSU Type 2,933


    Rural

    Urban
1.42 1.18, 1.71 <0.001
Wealth Index 2,933


    Higher

    Highest
0.62 0.47, 0.82 0.001
    Lower
1.31 1.01, 1.71 0.040
    Lowest
1.89 1.44, 2.50 <0.001
    Middle
0.92 0.71, 1.21 0.6
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Zinc Intake (mg/day) 2,933 0.91 0.87, 0.95 <0.001
Age Group 2,933


    0-2

    2-3
0.86 0.65, 1.13 0.3
    3-4
0.84 0.64, 1.10 0.2
    4-5
0.81 0.62, 1.06 0.12
Gender 2,933


    Female

    Male
1.27 1.07, 1.50 0.006
Type of House 2,933


    Kutcha

    Pucca
1.47 1.13, 1.93 0.005
    Semi-pucca
1.33 1.01, 1.75 0.046
PSU Type 2,933


    Rural

    Urban
1.41 1.17, 1.69 <0.001
Wealth Index 2,933


    Higher

    Highest
0.63 0.47, 0.83 0.001
    Lower
1.31 1.01, 1.70 0.045
    Lowest
1.89 1.44, 2.50 <0.001
    Middle
0.92 0.71, 1.21 0.6
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Calcium Intake (mg/day) 2,933 1.00 1.00, 1.00 0.013
Age Group 2,933


    0-2

    2-3
0.81 0.62, 1.07 0.14
    3-4
0.77 0.59, 1.01 0.061
    4-5
0.71 0.55, 0.93 0.012
Gender 2,933


    Female

    Male
1.26 1.06, 1.49 0.007
Type of House 2,933


    Kutcha

    Pucca
1.51 1.15, 1.98 0.003
    Semi-pucca
1.35 1.02, 1.78 0.034
PSU Type 2,933


    Rural

    Urban
1.42 1.18, 1.70 <0.001
Wealth Index 2,933


    Higher

    Highest
0.63 0.48, 0.84 0.002
    Lower
1.31 1.01, 1.70 0.044
    Lowest
1.90 1.44, 2.50 <0.001
    Middle
0.93 0.71, 1.21 0.6
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio
Characteristic N OR1 95% CI p-value
Vitamin C Intake (mg/day) 2,933 1.00 0.99, 1.00 0.066
Age Group 2,933


    0-2

    2-3
0.81 0.62, 1.08 0.15
    3-4
0.78 0.59, 1.02 0.066
    4-5
0.72 0.56, 0.95 0.018
Gender 2,933


    Female

    Male
1.26 1.06, 1.49 0.007
Type of House 2,933


    Kutcha

    Pucca
1.43 1.10, 1.88 0.009
    Semi-pucca
1.31 1.00, 1.73 0.056
PSU Type 2,933


    Rural

    Urban
1.40 1.17, 1.69 <0.001
Wealth Index 2,933


    Higher

    Highest
0.62 0.47, 0.83 0.001
    Lower
1.32 1.02, 1.71 0.038
    Lowest
1.95 1.48, 2.57 <0.001
    Middle
0.93 0.71, 1.21 0.6
1 Adjusted for age group, gender, type of house, rural/urban, and wealth index
Abbreviations: CI = Confidence Interval, OR = Odds Ratio

Note: Each variable is a separate logistic regression model adjusted for a common set of variables (age, gender, rural/urban and wealth index). Following are the potential risk factors for high blood lead levels in children:

  • RO/bottled/purchased water (OR = 1.42, 95% CI: 1.10–1.84, p = 0.006) were associated with higher odds of elevated blood lead levels.

  • Children with severe stunting (OR = 1.47, 95% CI: 1.13 - 1.90, p = 0.003) and severe underweight status (OR = 1.65, 95% CI: 1.21–2.23, p = 0.001) were associated with higher odds of elevated blood lead levels.

  • Iron deficiency (OR = 2.01, 95% CI: 1.38 - 2.92, p < 0.001) and any anaemia (OR = 1.25, 95% CI: 1.07–1.46, p = 0.004) were associated with higher odds of elevated blood lead levels.

  • Notably, the concurrent presence of both anaemia and iron deficiency amplified these odds more than two fold (OR = 2.32, 95% CI: 1.23–4.32, p = 0.008).

  • Consistent with the bio marker findings, higher daily dietary intakes of iron and zinc were protective, reducing the odds by 4% (OR = 0.95, 95% CI: 0.93–0.97, p < 0.001) and 8% (OR = 0.91, 95% CI: 0.87–0.95, p < 0.001) per 20 unit increase, respectively.

Summary of adjusted regression analysis of the full SAMPADA data

1. Drinking water source: RO/bottled water and water tanker as a drinking water source were associated with higher risk

2. Malnutrition status: Severe stunting and underweight status were associated with higher risk

3. Micronutrient deficiency: Iron deficiency and anemia were associated with higher risk

4. Diet poor in micronutrients: Higher iron and zinc intake were associated with lower risk