Childhood Blood Level Analysis Using Full SAMPADA Data

Author

ICMR

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 = 4,306 N = 3,413
Blood Pb Levels (μg/dL) 4.7 (3.9), 3.6 (2.4, 5.7), 0.2, 42.5 4.7 (4.4), 3.1 (2.2, 6.4), 0.2, 42.5
bloodpblevelsmgdl_5cat
<4 2,437 (56.60%) 2,437 (71.40%)
4-6 893 (20.74%) 0 (0.00%)
6-10 647 (15.03%) 647 (18.96%)
10-20 275 (6.39%) 275 (8.06%)
>20 54 (1.25%) 54 (1.58%)
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 insights 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 (µg/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >6)
Characteristic N = 3,413 N Mean Difference 95% CI p-value Overall
N = 3,413
<4
N = 2,437
>6
N = 976
p-value PR 95% CI p-value
PSU Rural/Urban 3,413 0.003
Rural 4.6 (4.4) 2,344 (100%) 1,710 (73%) 634 (27%)
Urban 4.9 (4.4) 0.28 -0.04, 0.60 0.084 1,069 (100%) 727 (68%) 342 (32%) 1.18 1.06, 1.32 0.003
Gender 3,413 0.014
Female 4.5 (4.2) 1,624 (100%) 1,192 (73%) 432 (27%)
Male 4.9 (4.5) 0.42 0.12, 0.71 0.005 1,789 (100%) 1,245 (70%) 544 (30%) 1.14 1.03, 1.27 0.014
age_gp 3,413 0.067
1-2 5.2 (5.0) 501 (100%) 333 (66%) 168 (34%)
2-3 4.5 (3.9) -0.75 -1.2, -0.26 0.003 807 (100%) 581 (72%) 226 (28%) 0.84 0.71, 0.99 0.033
3-4 4.8 (4.6) -0.46 -0.93, 0.02 0.058 963 (100%) 693 (72%) 270 (28%) 0.84 0.71, 0.98 0.028
4-5 4.6 (4.2) -0.64 -1.1, -0.18 0.006 1,142 (100%) 830 (73%) 312 (27%) 0.81 0.70, 0.95 0.010
Caste 3,399 <0.001
Other Caste 4.1 (3.6) 677 (100%) 521 (77%) 156 (23%)
SC 4.9 (4.3) 0.76 0.31, 1.2 <0.001 774 (100%) 533 (69%) 241 (31%) 1.35 1.14, 1.61 <0.001
ST 3.9 (3.7) -0.21 -0.66, 0.25 0.4 717 (100%) 580 (81%) 137 (19%) 0.83 0.68, 1.02 0.072
OBC 5.5 (5.1) 1.4 0.96, 1.8 <0.001 1,183 (100%) 760 (64%) 423 (36%) 1.55 1.33, 1.82 <0.001
Not known 4.1 (2.8) 0.00 -1.3, 1.3 >0.9 48 (100%) 33 (69%) 15 (31%) 1.36 0.83, 2.01 0.2
Religion 3,399 <0.001
Hindu 5.1 (4.7) 2,560 (100%) 1,712 (67%) 848 (33%)
Muslim 4.0 (3.9) -1.2 -1.7, -0.64 <0.001 296 (100%) 236 (80%) 60 (20%) 0.61 0.48, 0.76 <0.001
Christian 3.3 (2.5) -1.8 -2.3, -1.3 <0.001 361 (100%) 313 (87%) 48 (13%) 0.40 0.30, 0.52 <0.001
Others 2.8 (2.3) -2.3 -2.9, -1.6 <0.001 182 (100%) 166 (91%) 16 (8.8%) 0.27 0.16, 0.41 <0.001
Unknown 14 10 4
Unknown 14 10 4
1 Blood Pb Levels (μg/dL): Mean (SD)
2 n (%)
3 Pearson's Chi-squared test

Findings: Urban residence, male, younger age, scheduled caste, 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 (µg/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >6)
Characteristic N = 3,413 N Mean Difference 95% CI p-value Overall
N = 3,413
<4
N = 2,437
>6
N = 976
p-value PR 95% CI p-value
Type of Family 3,399 0.10
Extended 4.3 (4.0) 428 (100%) 322 (75%) 106 (25%)
Joint 4.7 (4.6) 0.36 -0.16, 0.88 0.2 756 (100%) 547 (72%) 209 (28%) 1.12 0.92, 1.37 0.3
Nuclear 4.8 (4.4) 0.41 -0.04, 0.87 0.075 2,215 (100%) 1,558 (70%) 657 (30%) 1.20 1.01, 1.44 0.046
Ownership of house 3,385 0.7
Own House 4.7 (4.5) 2,988 (100%) 2,138 (72%) 850 (28%)
Rented/Other 4.6 (3.6) -0.10 -0.56, 0.36 0.7 397 (100%) 280 (71%) 117 (29%) 1.04 0.88, 1.21 0.7
Type of House 3,397 0.4
Pucca 4.6 (4.3) 2,048 (100%) 1,479 (72%) 569 (28%)
Semi-pucca 4.7 (4.3) 0.15 -0.20, 0.50 0.4 855 (100%) 598 (70%) 257 (30%) 1.08 0.95, 1.22 0.2
Kutcha 5.0 (4.8) 0.41 -0.02, 0.84 0.062 494 (100%) 350 (71%) 144 (29%) 1.05 0.90, 1.22 0.5
No of rooms in house 3,388 <0.001
>1 4.6 (4.4) 3,062 (100%) 2,228 (73%) 834 (27%)
0-1 5.8 (4.5) 1.2 0.66, 1.7 <0.001 326 (100%) 190 (58%) 136 (42%) 1.53 1.32, 1.75 <0.001
Separate Kitchen 3,396 0.017
Yes 4.5 (4.2) 2,436 (100%) 1,767 (73%) 669 (27%)
No 5.1 (4.7) 0.56 0.23, 0.89 <0.001 960 (100%) 657 (68%) 303 (32%) 1.15 1.02, 1.29 0.016
Cooking fuel 3,413 0.043
Firewood 4.8 (4.6) 1,076 (100%) 774 (72%) 302 (28%)
LPG 4.6 (4.3) -0.20 -0.52, 0.12 0.2 2,268 (100%) 1,623 (72%) 645 (28%) 1.01 0.90, 1.14 0.8
Others 6.3 (5.5) 1.5 0.48, 2.6 0.004 69 (100%) 40 (58%) 29 (42%) 1.50 1.08, 1.96 0.007
Drinking Water 3,397 <0.001
Bore well 4.8 (4.8) 911 (100%) 658 (72%) 253 (28%)
Open well 4.1 (4.1) -0.72 -1.4, -0.08 0.028 219 (100%) 177 (81%) 42 (19%) 0.69 0.51, 0.91 0.013
Others 5.3 (5.2) 0.53 -0.21, 1.3 0.2 161 (100%) 107 (66%) 54 (34%) 1.21 0.94, 1.52 0.13
RO/Bottled/Purchased water 5.2 (4.1) 0.38 -0.13, 0.90 0.14 402 (100%) 252 (63%) 150 (37%) 1.34 1.14, 1.58 <0.001
Surface/Spring water 4.1 (3.2) -0.66 -1.5, 0.15 0.11 130 (100%) 95 (73%) 35 (27%) 0.97 0.70, 1.29 0.8
Tap water 4.5 (4.2) -0.27 -0.63, 0.09 0.14 1,488 (100%) 1,084 (73%) 404 (27%) 0.98 0.86, 1.12 0.7
Water tanker 5.6 (4.6) 0.77 -0.20, 1.7 0.12 86 (100%) 52 (60%) 34 (40%) 1.42 1.05, 1.85 0.014
Cooking water 3,395 0.005
Bore well 4.8 (4.8) 928 (100%) 669 (72%) 259 (28%)
Open well 4.1 (4.1) -0.67 -1.3, -0.02 0.042 221 (100%) 176 (80%) 45 (20%) 0.73 0.54, 0.95 0.028
Others 5.3 (5.6) 0.51 -0.20, 1.2 0.2 171 (100%) 116 (68%) 55 (32%) 1.15 0.89, 1.45 0.2
RO/Bottled/Purchased water 4.8 (3.6) 0.05 -0.57, 0.67 0.9 244 (100%) 160 (66%) 84 (34%) 1.23 1.00, 1.50 0.041
Surface/Spring water 4.2 (3.3) -0.55 -1.3, 0.25 0.2 133 (100%) 96 (72%) 37 (28%) 1.00 0.73, 1.31 >0.9
Tap water 4.6 (4.2) -0.18 -0.53, 0.17 0.3 1,608 (100%) 1,153 (72%) 455 (28%) 1.01 0.89, 1.16 0.8
Water tanker 5.6 (4.6) 0.85 -0.10, 1.8 0.079 90 (100%) 54 (60%) 36 (40%) 1.43 1.07, 1.85 0.010
Water purification method 3,398 <0.001
Water filter/ E. Purifier 3.8 (3.9) 245 (100%) 199 (81%) 46 (19%)
Boiling 3.7 (3.0) -0.09 -0.73, 0.56 0.8 603 (100%) 482 (80%) 121 (20%) 1.07 0.79, 1.47 0.7
Strain through a cloth 5.0 (4.3) 1.2 0.41, 2.0 0.003 236 (100%) 157 (67%) 79 (33%) 1.78 1.31, 2.47 <0.001
Add bleach/chlorine tablets 6.6 (5.3) 2.8 1.0, 4.6 0.002 26 (100%) 13 (50%) 13 (50%) 2.66 1.58, 4.09 <0.001
None 5.2 (4.8) 1.4 0.84, 2.0 <0.001 1,975 (100%) 1,317 (67%) 658 (33%) 1.77 1.38, 2.36 <0.001
Others/Multiple 3.8 (3.3) 0.03 -0.70, 0.76 >0.9 313 (100%) 258 (82%) 55 (18%) 0.94 0.66, 1.34 0.7
Latrine type 3,413 <0.001
Present and using 4.6 (4.3) 2,914 (100%) 2,105 (72%) 809 (28%)
Others 3.8 (3.1) -0.81 -1.5, -0.14 0.017 175 (100%) 138 (79%) 37 (21%) 0.76 0.56, 1.00 0.068
Open Defecation 6.0 (5.4) 1.4 0.94, 1.9 <0.001 324 (100%) 194 (60%) 130 (40%) 1.45 1.24, 1.66 <0.001
Unknown 14 10 4
Unknown 28 19 9
Unknown 16 10 6
Unknown 25 19 6
Unknown 17 13 4
Unknown 16 12 4
Unknown 18 13 5
Unknown 15 11 4
1 Blood Pb Levels (μg/dL): Mean (SD)
2 n (%)
3 Pearson's Chi-squared test

Findings: Nuclear family, small houses, no separate kitchen, water from RO/bottled/water tanker, inadequate or improper 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 (µg/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >6)
Characteristic N = 3,413 N Mean Difference 95% CI p-value Overall
N = 3,413
<4
N = 2,437
>6
N = 976
p-value PR 95% CI p-value
Electricity Available 3,397 >0.9
No 4.0 (3.4) 16 (100%) 12 (75%) 4 (25%)
Yes 4.7 (4.4) 0.70 -1.5, 2.9 0.5 3,381 (100%) 2,413 (71%) 968 (29%) 1.15 0.58, 3.36 0.8
Electric Fan 3,399 0.012
No 4.3 (4.4) 377 (100%) 290 (77%) 87 (23%)
Yes 4.8 (4.4) 0.48 0.01, 0.95 0.044 3,022 (100%) 2,137 (71%) 885 (29%) 1.27 1.06, 1.55 0.015
Black and White Television 3,399 0.027
No 4.7 (4.4) 3,167 (100%) 2,276 (72%) 891 (28%)
Yes 5.2 (4.5) 0.55 -0.04, 1.1 0.068 232 (100%) 151 (65%) 81 (35%) 1.24 1.02, 1.48 0.022
Colour Television 3,399 0.11
No 5.1 (5.1) 1,100 (100%) 766 (70%) 334 (30%)
Yes 4.5 (4.0) -0.60 -0.91, -0.28 <0.001 2,299 (100%) 1,661 (72%) 638 (28%) 0.91 0.82, 1.02 0.11
Radio/Transistor 3,399 0.022
No 4.8 (4.5) 3,152 (100%) 2,235 (71%) 917 (29%)
Yes 3.7 (2.9) -1.0 -1.6, -0.46 <0.001 247 (100%) 192 (78%) 55 (22%) 0.77 0.59, 0.96 0.029
Pressure Cooker 3,399 <0.001
No 5.7 (5.4) 810 (100%) 514 (63%) 296 (37%)
Yes 4.4 (4.0) -1.3 -1.6, -0.92 <0.001 2,589 (100%) 1,913 (74%) 676 (26%) 0.71 0.64, 0.80 <0.001
Cot/Bed 3,399 <0.001
No 5.5 (4.8) 470 (100%) 292 (62%) 178 (38%)
Yes 4.6 (4.3) -0.92 -1.3, -0.49 <0.001 2,929 (100%) 2,135 (73%) 794 (27%) 0.72 0.63, 0.82 <0.001
Mattress 3,399 <0.001
No 5.9 (5.2) 886 (100%) 529 (60%) 357 (40%)
Yes 4.3 (4.0) -1.6 -2.0, -1.3 <0.001 2,513 (100%) 1,898 (76%) 615 (24%) 0.61 0.55, 0.68 <0.001
Chair 3,399 <0.001
No 5.5 (4.6) 347 (100%) 212 (61%) 135 (39%)
Yes 4.6 (4.4) -0.85 -1.3, -0.36 <0.001 3,052 (100%) 2,215 (73%) 837 (27%) 0.70 0.61, 0.82 <0.001
Table 3,399 <0.001
No 5.5 (4.9) 994 (100%) 635 (64%) 359 (36%)
Yes 4.4 (4.1) -1.1 -1.4, -0.78 <0.001 2,405 (100%) 1,792 (75%) 613 (25%) 0.71 0.63, 0.79 <0.001
Mobile Phone 3,399 0.054
No 5.1 (4.3) 171 (100%) 111 (65%) 60 (35%)
Yes 4.7 (4.4) -0.45 -1.1, 0.22 0.2 3,228 (100%) 2,316 (72%) 912 (28%) 0.81 0.66, 1.01 0.044
Landline Phone 3,399 0.2
No 4.7 (4.4) 3,311 (100%) 2,359 (71%) 952 (29%)
Yes 4.2 (3.5) -0.54 -1.5, 0.39 0.3 88 (100%) 68 (77%) 20 (23%) 0.79 0.51, 1.12 0.2
Watch/Clock 3,370 0.029
No 4.9 (4.6) 1,038 (100%) 714 (69%) 324 (31%)
Yes 4.6 (4.3) -0.28 -0.60, 0.04 0.086 2,332 (100%) 1,690 (72%) 642 (28%) 0.88 0.79, 0.99 0.028
Washing Machine 3,399 <0.001
No 4.8 (4.5) 2,521 (100%) 1,760 (70%) 761 (30%)
Yes 4.3 (4.2) -0.50 -0.83, -0.16 0.004 878 (100%) 667 (76%) 211 (24%) 0.80 0.70, 0.91 <0.001
Refrigerator 3,399 <0.001
No 5.0 (4.6) 1,779 (100%) 1,220 (69%) 559 (31%)
Yes 4.4 (4.1) -0.62 -0.92, -0.33 <0.001 1,620 (100%) 1,207 (75%) 413 (25%) 0.81 0.73, 0.90 <0.001
Computer 3,399 0.022
No 4.7 (4.4) 3,195 (100%) 2,267 (71%) 928 (29%)
Yes 4.1 (3.6) -0.60 -1.2, 0.02 0.059 204 (100%) 160 (78%) 44 (22%) 0.74 0.56, 0.95 0.029
Internet 3,399 <0.001
No 5.0 (4.6) 1,585 (100%) 1,075 (68%) 510 (32%)
Yes 4.5 (4.2) -0.49 -0.78, -0.19 0.001 1,814 (100%) 1,352 (75%) 462 (25%) 0.79 0.71, 0.88 <0.001
Sewing Machine 3,399 0.5
No 4.7 (4.4) 2,866 (100%) 2,040 (71%) 826 (29%)
Yes 4.6 (4.3) -0.08 -0.48, 0.33 0.7 533 (100%) 387 (73%) 146 (27%) 0.95 0.81, 1.10 0.5
Air Conditioner/Cooler 3,399 0.6
No 4.7 (4.3) 2,821 (100%) 2,019 (72%) 802 (28%)
Yes 4.9 (4.7) 0.24 -0.15, 0.64 0.2 578 (100%) 408 (71%) 170 (29%) 1.03 0.90, 1.18 0.6
Bicycle 3,399 0.7
No 4.7 (4.2) 2,181 (100%) 1,552 (71%) 629 (29%)
Yes 4.7 (4.7) 0.07 -0.24, 0.37 0.7 1,218 (100%) 875 (72%) 343 (28%) 0.98 0.87, 1.09 0.7
Motorcycle/Scooter 3,399 0.031
No 4.6 (4.5) 1,603 (100%) 1,173 (73%) 430 (27%)
Yes 4.8 (4.3) 0.16 -0.14, 0.45 0.3 1,796 (100%) 1,254 (70%) 542 (30%) 1.13 1.01, 1.25 0.031
Car/Four Wheeler 3,399 <0.001
No 4.8 (4.5) 2,988 (100%) 2,087 (70%) 901 (30%)
Yes 3.7 (3.6) -1.1 -1.6, -0.69 <0.001 411 (100%) 340 (83%) 71 (17%) 0.57 0.46, 0.71 <0.001
Animal Drawn Cart 3,399 0.10
No 4.7 (4.4) 3,218 (100%) 2,288 (71%) 930 (29%)
Yes 4.1 (3.4) -0.66 -1.3, 0.00 0.048 181 (100%) 139 (77%) 42 (23%) 0.80 0.60, 1.03 0.11
Water Pump 3,399 0.5
No 4.7 (4.3) 2,924 (100%) 2,082 (71%) 842 (29%)
Yes 4.7 (4.8) -0.02 -0.44, 0.41 >0.9 475 (100%) 345 (73%) 130 (27%) 0.95 0.81, 1.11 0.5
Tractor 3,399 0.2
No 4.7 (4.4) 3,293 (100%) 2,357 (72%) 936 (28%)
Yes 5.0 (4.8) 0.36 -0.49, 1.2 0.4 106 (100%) 70 (66%) 36 (34%) 1.19 0.89, 1.53 0.2
Thresher/Seed Removal Machine 3,399 0.8
No 4.7 (4.4) 3,359 (100%) 2,399 (71%) 960 (29%)
Yes 4.9 (5.1) 0.18 -1.2, 1.5 0.8 40 (100%) 28 (70%) 12 (30%) 1.05 0.61, 1.59 0.8
Home Theatre 3,399 0.7
No 4.7 (4.4) 3,321 (100%) 2,373 (71%) 948 (29%)
Yes 4.5 (3.3) -0.24 -1.2, 0.75 0.6 78 (100%) 54 (69%) 24 (31%) 1.08 0.74, 1.46 0.7
Vacuum Cleaner 3,399 0.059
No 4.7 (4.4) 3,333 (100%) 2,373 (71%) 960 (29%)
Yes 3.2 (2.7) -1.5 -2.6, -0.44 0.006 66 (100%) 54 (82%) 12 (18%) 0.63 0.35, 1.00 0.080
Microwave/Electric Oven 3,399 <0.001
No 4.7 (4.4) 3,307 (100%) 2,346 (71%) 961 (29%)
Yes 3.2 (3.7) -1.5 -2.4, -0.62 <0.001 92 (100%) 81 (88%) 11 (12%) 0.41 0.22, 0.68 0.002
Treadmill/Exercise Equipment 3,399 0.11
No 4.7 (4.4) 3,387 (100%) 2,421 (71%) 966 (29%)
Yes 5.0 (2.6) 0.35 -2.1, 2.8 0.8 12 (100%) 6 (50%) 6 (50%) 1.75 0.83, 2.68 0.053
Type of PDS/Ration Card 3,395 0.019
APL 4.4 (4.5) 720 (100%) 542 (75%) 178 (25%)
No card 4.8 (4.3) 0.38 -0.08, 0.85 0.11 652 (100%) 469 (72%) 183 (28%) 1.14 0.95, 1.36 0.2
BPL/AAY/TPDS 4.8 (4.4) 0.40 0.03, 0.78 0.035 2,023 (100%) 1,412 (70%) 611 (30%) 1.22 1.06, 1.42 0.006
Any Woman Enrolled in a Self-Help Group 3,381 0.3
No 4.6 (4.3) 2,344 (100%) 1,687 (72%) 657 (28%)
Yes 4.8 (4.5) 0.20 -0.12, 0.52 0.2 1,037 (100%) 727 (70%) 310 (30%) 1.07 0.95, 1.19 0.3
Any Household Member with Disability 3,393 0.7
No 4.6 (4.2) 2,526 (100%) 1,808 (72%) 718 (28%)
Yes 4.9 (4.8) 0.25 -0.09, 0.59 0.14 867 (100%) 614 (71%) 253 (29%) 1.03 0.91, 1.16 0.7
Household Covered by Insurance 3,396 0.009
No 4.9 (4.4) 1,581 (100%) 1,095 (69%) 486 (31%)
Yes 4.5 (4.4) -0.32 -0.62, -0.02 0.034 1,815 (100%) 1,331 (73%) 484 (27%) 0.87 0.78, 0.96 0.009
Household Owns Agricultural Land 3,324 <0.001
No 4.5 (4.2) 2,336 (100%) 1,715 (73%) 621 (27%)
Yes 5.1 (4.7) 0.59 0.27, 0.92 <0.001 988 (100%) 661 (67%) 327 (33%) 1.25 1.11, 1.39 <0.001
Owns Livestock 3,273 0.2
No 4.6 (4.1) 2,453 (100%) 1,765 (72%) 688 (28%)
Yes 5.0 (5.0) 0.38 0.03, 0.72 0.033 820 (100%) 571 (70%) 249 (30%) 1.08 0.96, 1.22 0.2
Cows/Bulls/Buffaloes/Yaks 748 >0.9
No 5.2 (5.8) 131 (100%) 91 (69%) 40 (31%)
Yes 5.0 (5.0) -0.20 -1.2, 0.76 0.7 617 (100%) 427 (69%) 190 (31%) 1.01 0.77, 1.36 >0.9
Camels 569 >0.9
No 4.8 (4.9) 566 (100%) 406 (72%) 160 (28%)
Yes 4.3 (2.2) -0.48 -6.0, 5.0 0.9 3 (100%) 2 (67%) 1 (33%) 1.18 0.24, 5.87 0.8
Horses/Donkeys/Mules 565 0.5
No 4.8 (4.8) 563 (100%) 404 (72%) 159 (28%)
Yes 6.0 (3.0) 1.2 -5.5, 7.9 0.7 2 (100%) 1 (50%) 1 (50%) 1.77 0.44, 7.12 0.4
Goats/Sheep 659 0.077
No 4.6 (4.4) 366 (100%) 268 (73%) 98 (27%)
Yes 5.3 (5.4) 0.76 0.01, 1.5 0.046 293 (100%) 196 (67%) 97 (33%) 1.24 0.98, 1.57 0.077
Pigs 577 0.2
No 4.9 (4.9) 524 (100%) 370 (71%) 154 (29%)
Yes 4.4 (5.5) -0.53 -1.9, 0.87 0.5 53 (100%) 42 (79%) 11 (21%) 0.71 0.38, 1.14 0.2
Chickens/Ducks 645 0.019
No 5.1 (4.8) 379 (100%) 257 (68%) 122 (32%)
Yes 4.6 (5.2) -0.51 -1.3, 0.27 0.2 266 (100%) 203 (76%) 63 (24%) 0.74 0.56, 0.95 0.021
Wealth Index 3,399 <0.001
Highest 4.2 (4.1) 641 (100%) 499 (78%) 142 (22%)
Higher 4.6 (4.2) 0.37 -0.10, 0.84 0.12 680 (100%) 493 (73%) 187 (28%) 1.24 1.03, 1.50 0.025
Middle 4.3 (3.6) 0.08 -0.39, 0.56 0.7 659 (100%) 494 (75%) 165 (25%) 1.13 0.93, 1.38 0.2
Lower 4.5 (4.1) 0.35 -0.11, 0.81 0.14 718 (100%) 510 (71%) 208 (29%) 1.31 1.09, 1.58 0.004
Lowest 5.9 (5.4) 1.7 1.2, 2.2 <0.001 701 (100%) 431 (61%) 270 (39%) 1.74 1.47, 2.07 <0.001
Unknown 16 12 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 43 33 10
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 14 10 4
Unknown 18 14 4
Unknown 32 23 9
Unknown 20 15 5
Unknown 17 11 6
Unknown 89 61 28
Unknown 140 101 39
Unknown 2,665 1,919 746
Unknown 2,844 2,029 815
Unknown 2,848 2,032 816
Unknown 2,754 1,973 781
Unknown 2,836 2,025 811
Unknown 2,768 1,977 791
Unknown 14 10 4
1 Blood Pb Levels (μg/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 (µg/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >6)
Characteristic N = 3,413 N Mean Difference 95% CI p-value Overall
N = 3,413
<4
N = 2,437
>6
N = 976
p-value PR 95% CI p-value
Anemia status 3,413 <0.001
No Anemia 4.5 (4.1) 2,213 (100%) 1,624 (73%) 589 (27%)
Any Anemia 5.1 (4.8) 0.68 0.38, 0.99 <0.001 1,200 (100%) 813 (68%) 387 (32%) 1.21 1.09, 1.35 <0.001
Anaemia Status (Any, New) 3,413 <0.001
No Anemia 4.5 (4.1) 2,213 (100%) 1,624 (73%) 589 (27%)
Mild Anemia 4.9 (4.7) 0.49 0.12, 0.87 0.010 685 (100%) 479 (70%) 206 (30%) 1.13 0.99, 1.29 0.073
Moder+Sev Anemia 5.4 (4.9) 0.94 0.52, 1.4 <0.001 515 (100%) 334 (65%) 181 (35%) 1.32 1.15, 1.51 <0.001
Iron Deficiency Status 741 0.001
No Iron Deficiency 4.2 (3.7) 571 (100%) 434 (76%) 137 (24%)
Iron Deficiency (ID) 5.5 (4.9) 1.3 0.56, 1.9 <0.001 170 (100%) 108 (64%) 62 (36%) 1.52 1.18, 1.93 <0.001
iron_def_adj 714 0.009
No Iron Deficiency 4.1 (3.8) 410 (100%) 321 (78%) 89 (22%)
Iron Deficiency 4.8 (4.2) 0.70 0.11, 1.3 0.021 304 (100%) 212 (70%) 92 (30%) 1.39 1.08, 1.79 0.009
Anaemia Adjusted for Iron 739 0.066
No Anemia + Iron Deficiency 3.2 (2.2) 33 (100%) 29 (88%) 4 (12%)
Anemia + No Iron Deficiency 4.3 (3.7) 1.1 -0.37, 2.6 0.14 223 (100%) 166 (74%) 57 (26%) 2.11 0.95, 6.62 0.12
No Anemia + No Iron Deficiency 4.7 (4.3) 1.4 -0.01, 2.9 0.051 457 (100%) 330 (72%) 127 (28%) 2.29 1.05, 7.13 0.081
Anemia + Iron Deficiency 5.3 (4.0) 2.0 -0.06, 4.1 0.057 26 (100%) 15 (58%) 11 (42%) 3.49 1.37, 11.5 0.017
Vitamin B12 Status 708 0.8
Normal (≥203 pg/mL) 4.5 (4.0) 441 (100%) 324 (73%) 117 (27%)
Deficient (<203 pg/mL) 4.6 (4.4) 0.08 -0.55, 0.71 0.8 267 (100%) 194 (73%) 73 (27%) 1.03 0.80, 1.32 0.8
Serum Folate Status 707 0.4
Normal (≥4 ng/mL) 4.5 (4.1) 612 (100%) 445 (73%) 167 (27%)
Deficient (<4 ng/mL) 4.3 (4.1) -0.25 -1.1, 0.65 0.6 95 (100%) 73 (77%) 22 (23%) 0.85 0.56, 1.22 0.4
Vitamin D Status 705 0.3
Normal (≥12 ng/mL) 4.5 (3.8) 576 (100%) 426 (74%) 150 (26%)
Deficient (<12 ng/mL) 4.9 (5.3) 0.43 -0.36, 1.2 0.3 129 (100%) 89 (69%) 40 (31%) 1.19 0.87, 1.57 0.2
Unknown 2,672 1,895 777
Unknown 2,699 1,904 795
Unknown 2,674 1,897 777
Unknown 2,705 1,919 786
Unknown 2,706 1,919 787
Unknown 2,708 1,922 786
1 Blood Pb Levels (μg/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
ferritin_clean -0.110 0.0026
log_ferritin -0.164 0.0000
ferritin_adj -0.079 0.0344
log_ferritin_adj -0.103 0.0059
folate_ng_ml 0.053 0.1614
rbc_folate_ng_ml -0.038 0.3336
b12_pg_ml -0.069 0.0665
vitd_ng_ml 0.029 0.4373

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 (µg/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >6)
Characteristic N = 3,413 N Mean Difference 95% CI p-value Overall
N = 3,413
<4
N = 2,437
>6
N = 976
p-value PR 95% CI p-value
CRP Status 748 0.040
Inflammation 3.6 (2.9) 58 (100%) 49 (84%) 9 (16%)
No Inflammation 4.6 (4.1) 1.0 -0.08, 2.1 0.069 690 (100%) 497 (72%) 193 (28%) 1.80 1.05, 3.63 0.059
AGP Status 746 0.2
Inflammation 4.0 (3.2) 95 (100%) 74 (78%) 21 (22%)
No Inflammation 4.6 (4.2) 0.59 -0.29, 1.5 0.2 651 (100%) 470 (72%) 181 (28%) 1.26 0.87, 1.94 0.3
Inflammation Status 747 0.050
Inflammation 3.8 (3.0) 117 (100%) 94 (80%) 23 (20%)
No Inflammation 4.7 (4.2) 0.90 0.10, 1.7 0.027 630 (100%) 451 (72%) 179 (28%) 1.45 1.01, 2.20 0.062
Unknown 2,665 1,891 774
Unknown 2,667 1,893 774
Unknown 2,666 1,892 774
1 Blood Pb Levels (μg/dL): Mean (SD)
2 n (%)
3 Pearson's Chi-squared test
Correlation between Inflammation markers and Blood Pb levels
Inflammation markers Correlation Coefficient (r) P-value
crphs_clean -0.067 0.0662
agp_clean -0.081 0.0272
log_crp -0.098 0.0081
log_agp -0.080 0.0281

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 (µg/dL)
Mean Difference
Distribution by Blood Pb Categories
Prevalence Ratio (<4 vs. >6)
Characteristic N = 3,413 N Mean Difference 95% CI p-value Overall
N = 3,413
<4
N = 2,437
>6
N = 976
p-value PR 95% CI p-value
Stunting status 2,787 <0.001
No Stunting 4.5 (4.1) 1,982 (100%) 1,438 (73%) 544 (27%)
Stunting 5.1 (4.7) 0.57 0.15, 0.99 0.008 530 (100%) 352 (66%) 178 (34%) 1.22 1.06, 1.40 0.005
Severe Stunting 6.0 (5.5) 1.5 0.95, 2.1 <0.001 275 (100%) 167 (61%) 108 (39%) 1.43 1.21, 1.67 <0.001
Wasting status 2,761 0.6
No Wasting 4.7 (4.3) 2,384 (100%) 1,682 (71%) 702 (29%)
Wasting 5.1 (5.0) 0.36 -0.16, 0.89 0.2 305 (100%) 209 (69%) 96 (31%) 1.07 0.89, 1.27 0.5
Severe Wasting 4.9 (4.0) 0.23 -0.80, 1.3 0.7 72 (100%) 48 (67%) 24 (33%) 1.13 0.78, 1.53 0.5
Underweight status 2,807 <0.001
No Underweight 4.5 (4.2) 2,105 (100%) 1,520 (72%) 585 (28%)
Underweight 5.4 (5.0) 0.90 0.47, 1.3 <0.001 519 (100%) 342 (66%) 177 (34%) 1.23 1.07, 1.40 0.004
Severe Underweight 5.6 (4.8) 1.1 0.40, 1.7 0.002 183 (100%) 111 (61%) 72 (39%) 1.42 1.15, 1.70 <0.001
MUAC Group 2,815 0.064
Normal 4.7 (4.4) 2,753 (100%) 1,942 (71%) 811 (29%)
severewasting 5.0 (3.6) 0.27 -0.84, 1.4 0.6 62 (100%) 37 (60%) 25 (40%) 1.37 0.97, 1.80 0.046
Unknown 626 480 146
Unknown 652 498 154
Unknown 606 464 142
Unknown 598 458 140
1 Blood Pb Levels (μg/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
Nutritional Variable Correlation Coefficient (r) P-value
Energy Intake (kcal/day) -0.058 0.0032
Protein Intake (g/day) -0.092 0.0000
Carbohydrate Intake (g/day) -0.039 0.0482
Total Fat Intake (g/day) -0.054 0.0055
Iron Intake (mg/day) -0.081 0.0000
Zinc Intake (mg/day) -0.091 0.0000
Calcium Intake (mg/day) -0.084 0.0000
Thiamine (B1) Intake (mg/day) -0.089 0.0000
Riboflavin (B2) Intake (mg/day) -0.086 0.0000
Niacin (B3) Intake (mg/day) -0.064 0.0011
Total Folate (B9) Intake (ug/day) -0.105 0.0000
Vitamin C Intake (mg/day) -0.051 0.0089
Vitamin A Intake (ug/day) -0.061 0.0018
Vitamin B12 Intake (ug/day) -0.010 0.5955
Birth Weight (grams) 0.041 0.4723
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) 0.998 0.996 0.999 0.0110
Protein Intake (g/day) 0.889 0.841 0.939 0.0000
Carbohydrate Intake (g/day) 0.989 0.977 0.999 0.0467
Total Fat Intake (g/day) 0.959 0.915 1.003 0.0708
Iron Intake (mg/day) 0.612 0.491 0.758 0.0000
Zinc Intake (mg/day) 0.381 0.252 0.570 0.0000
Calcium Intake (mg/day) 0.993 0.989 0.997 0.0004
Thiamine (B1) Intake (mg/day) 0.002 0.000 0.027 0.0000
Riboflavin (B2) Intake (mg/day) 0.001 0.000 0.028 0.0000
Niacin (B3) Intake (mg/day) 0.698 0.531 0.905 0.0084
Total Folate (B9) Intake (ug/day) 0.963 0.948 0.976 0.0000
Vitamin C Intake (mg/day) 0.965 0.937 0.993 0.0163
Vitamin A Intake (ug/day) 0.992 0.986 0.998 0.0137
Vitamin B12 Intake (ug/day) 0.871 0.132 2.323 0.8087
Birth Weight (grams) 1.000 0.996 1.005 0.9624

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 Blood Parameters and Blood Pb Levels
Nutritional Variable Correlation Coefficient (r) P-value
wbc 0.094 0.0000
lym_perc 0.035 0.0414
mono_perc -0.033 0.0554
gran_perc -0.025 0.1434
lym_mm 0.111 0.0000
mono_mm 0.024 0.1636
gra_mm 0.037 0.0320
rbc 0.120 0.0000
hgb -0.090 0.0000
hct -0.056 0.0010
mcv -0.163 0.0000
mch -0.116 0.0000
mchc -0.044 0.0096
rdwcv 0.130 0.0000
rdwsd -0.044 0.0094
plt 0.143 0.0000
tht 0.130 0.0000
mpv -0.060 0.0005
pdw -0.112 0.0000
eag 0.074 0.5479
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
wbc 1.89 1.49 2.41 0.00
lym_perc 1.10 1.04 1.18 0.00
mono_perc 0.75 0.58 0.95 0.02
gran_perc 0.93 0.87 0.99 0.01
lym_mm 4.30 2.86 6.50 0.00
mono_mm 2.92 0.47 17.46 0.24
gra_mm 1.27 0.91 1.77 0.16
rbc 71.03 19.04 269.73 0.00
hgb 0.32 0.20 0.51 0.00
hct 0.79 0.67 0.93 0.01
mcv 0.72 0.66 0.78 0.00
mch 0.52 0.43 0.63 0.00
mchc 0.67 0.48 0.90 0.01
rdwcv 3.40 2.38 4.87 0.00
rdwsd 0.84 0.71 0.98 0.03
plt 1.03 1.02 1.04 0.00
tht 63492439165171.31 15558399243.04 289524393857163328.00 0.00
mpv 0.25 0.14 0.45 0.00
pdw 0.51 0.42 0.62 0.00
eag 22.28 0.00 8984057.05 0.63

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 3,395


    Bore well

    Open well
0.68 0.46, 0.98 0.042
    Others
1.32 0.91, 1.89 0.14
    RO/Bottled/Purchased water
1.81 1.38, 2.38 <0.001
    Surface/Spring water
0.93 0.60, 1.41 0.7
    Tap water
1.02 0.84, 1.24 0.8
    Water tanker
1.70 1.06, 2.71 0.026
age_gp 3,395


    1-2

    2-3
0.75 0.59, 0.97 0.026
    3-4
0.75 0.59, 0.95 0.018
    4-5
0.70 0.56, 0.89 0.003
Gender 3,395


    Female

    Male
1.23 1.06, 1.43 0.008
Type of House 3,395


    Pucca

    Semi-pucca
0.93 0.76, 1.12 0.4
    Kutcha
0.79 0.61, 1.01 0.067
PSU Rural/Urban 3,395


    Rural

    Urban
1.38 1.16, 1.64 <0.001
Wealth Index 3,395


    Highest

    Higher
1.40 1.08, 1.81 0.011
    Middle
1.37 1.05, 1.79 0.022
    Lower
1.77 1.36, 2.32 <0.001
    Lowest
3.12 2.37, 4.14 <0.001
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 736


    No Iron Deficiency

    Iron Deficiency (ID)
1.70 1.15, 2.50 0.008
age_gp 736


    1-2

    2-3
1.27 0.67, 2.47 0.5
    3-4
0.97 0.53, 1.82
0.9
    4-5
0.99 0.56, 1.83
0.9
Gender 736


    Female

    Male
1.38 0.99, 1.94 0.059
Type of House 736


    Pucca

    Semi-pucca
0.75 0.46, 1.19 0.2
    Kutcha
0.90 0.52, 1.54 0.7
PSU Rural/Urban 736


    Rural

    Urban
1.41 0.97, 2.06 0.069
Wealth Index 736


    Highest

    Higher
1.25 0.74, 2.11 0.4
    Middle
1.16 0.67, 1.99 0.6
    Lower
1.76 1.00, 3.10 0.049
    Lowest
2.59 1.46, 4.65 0.001
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 status 3,397


    No Anemia

    Any Anemia
1.25 1.07, 1.47 0.005
age_gp 3,397


    1-2

    2-3
0.76 0.60, 0.98 0.032
    3-4
0.76 0.60, 0.97 0.026
    4-5
0.74 0.58, 0.93 0.010
Gender 3,397


    Female

    Male
1.23 1.06, 1.44 0.007
Type of House 3,397


    Pucca

    Semi-pucca
0.95 0.78, 1.14 0.6
    Kutcha
0.77 0.60, 0.99 0.040
PSU Rural/Urban 3,397


    Rural

    Urban
1.47 1.24, 1.74 <0.001
Wealth Index 3,397


    Highest

    Higher
1.35 1.04, 1.74 0.022
    Middle
1.26 0.97, 1.64 0.087
    Lower
1.62 1.25, 2.10 <0.001
    Lowest
2.77 2.12, 3.64 <0.001
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 703


    Normal (≥203 pg/mL)

    Deficient (<203 pg/mL)
0.95 0.66, 1.35 0.8
age_gp 703


    1-2

    2-3
1.29 0.67, 2.54 0.4
    3-4
0.93 0.51, 1.77 0.8
    4-5
0.93 0.52, 1.72 0.8
Gender 703


    Female

    Male
1.36 0.97, 1.92 0.080
Type of House 703


    Pucca

    Semi-pucca
0.72 0.45, 1.14 0.2
    Kutcha
0.82 0.47, 1.41 0.5
PSU Rural/Urban 703


    Rural

    Urban
1.39 0.95, 2.03 0.090
Wealth Index 703


    Highest

    Higher
1.23 0.73, 2.10 0.4
    Middle
1.18 0.68, 2.06 0.6
    Lower
1.71 0.97, 3.04 0.066
    Lowest
2.53 1.39, 4.63 0.002
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 702


    Normal (≥4 ng/mL)

    Deficient (<4 ng/mL)
0.77 0.44, 1.30 0.3
age_gp 702


    1-2

    2-3
1.24 0.65, 2.45 0.5
    3-4
0.92 0.50, 1.74 0.8
    4-5
0.92 0.51, 1.70 0.8
Gender 702


    Female

    Male
1.35 0.96, 1.90 0.090
Type of House 702


    Pucca

    Semi-pucca
0.72 0.44, 1.14 0.2
    Kutcha
0.85 0.48, 1.47 0.6
PSU Rural/Urban 702


    Rural

    Urban
1.42 0.97, 2.08 0.070
Wealth Index 702


    Highest

    Higher
1.22 0.72, 2.08 0.5
    Middle
1.14 0.65, 1.98 0.6
    Lower
1.67 0.94, 2.97 0.079
    Lowest
2.42 1.33, 4.43 0.004
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 700


    Normal (≥12 ng/mL)

    Deficient (<12 ng/mL)
1.22 0.78, 1.87 0.4
age_gp 700


    1-2

    2-3
1.28 0.66, 2.51 0.5
    3-4
0.91 0.49, 1.72 0.8
    4-5
0.91 0.51, 1.68 0.8
Gender 700


    Female

    Male
1.35 0.96, 1.91 0.085
Type of House 700


    Pucca

    Semi-pucca
0.72 0.44, 1.13 0.2
    Kutcha
0.81 0.46, 1.40 0.5
PSU Rural/Urban 700


    Rural

    Urban
1.36 0.93, 1.99 0.12
Wealth Index 700


    Highest

    Higher
1.23 0.73, 2.11 0.4
    Middle
1.20 0.69, 2.08 0.5
    Lower
1.75 0.99, 3.12 0.056
    Lowest
2.55 1.41, 4.65 0.002
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 Adjusted for Iron 734


    No Anemia + Iron Deficiency

    Anemia + No Iron Deficiency
2.24 0.82, 7.94 0.2
    No Anemia + No Iron Deficiency
2.73 1.03, 9.47 0.068
    Anemia + Iron Deficiency
4.72 1.31, 20.1 0.023
age_gp 734


    1-2

    2-3
1.33 0.70, 2.57 0.4
    3-4
0.97 0.53, 1.82
0.9
    4-5
0.94 0.53, 1.72 0.8
Gender 734


    Female

    Male
1.40 1.00, 1.96 0.053
Type of House 734


    Pucca

    Semi-pucca
0.67 0.42, 1.06 0.10
    Kutcha
0.76 0.44, 1.30 0.3
PSU Rural/Urban 734


    Rural

    Urban
1.37 0.94, 2.00 0.10
Wealth Index 734


    Highest

    Higher
1.32 0.78, 2.22 0.3
    Middle
1.22 0.71, 2.10 0.5
    Lower
1.86 1.06, 3.29 0.032
    Lowest
2.73 1.53, 4.90 <0.001
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 status 2,777


    No Stunting

    Stunting
1.28 1.03, 1.57 0.023
    Severe Stunting
1.54 1.17, 2.01 0.002
age_gp 2,777


    1-2

    2-3
0.70 0.54, 0.92 0.010
    3-4
0.74 0.57, 0.96 0.024
    4-5
0.70 0.54, 0.90 0.006
Gender 2,777


    Female

    Male
1.15 0.97, 1.36 0.10
Type of House 2,777


    Pucca

    Semi-pucca
0.93 0.76, 1.14 0.5
    Kutcha
0.72 0.55, 0.94 0.019
PSU Rural/Urban 2,777


    Rural

    Urban
1.54 1.28, 1.85 <0.001
Wealth Index 2,777


    Highest

    Higher
1.37 1.03, 1.84 0.031
    Middle
1.27 0.95, 1.71 0.11
    Lower
1.61 1.20, 2.17 0.001
    Lowest
2.68 1.98, 3.65 <0.001
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 status 2,751


    No Wasting

    Wasting
1.06 0.81, 1.37 0.7
    Severe Wasting
1.15 0.67, 1.89 0.6
age_gp 2,751


    1-2

    2-3
0.67 0.52, 0.88 0.004
    3-4
0.72 0.56, 0.94 0.013
    4-5
0.66 0.51, 0.85 0.001
Gender 2,751


    Female

    Male
1.16 0.98, 1.37 0.085
Type of House 2,751


    Pucca

    Semi-pucca
0.92 0.75, 1.13 0.4
    Kutcha
0.73 0.56, 0.96 0.025
PSU Rural/Urban 2,751


    Rural

    Urban
1.49 1.24, 1.79 <0.001
Wealth Index 2,751


    Highest

    Higher
1.38 1.03, 1.84 0.030
    Middle
1.29 0.96, 1.74 0.089
    Lower
1.71 1.28, 2.29 <0.001
    Lowest
2.88 2.13, 3.92 <0.001
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
Underweight status 2,797


    No Underweight

    Underweight
1.26 1.02, 1.56 0.030
    Severe Underweight
1.55 1.12, 2.12 0.007
age_gp 2,797


    1-2

    2-3
0.68 0.52, 0.89 0.005
    3-4
0.72 0.56, 0.93 0.013
    4-5
0.67 0.52, 0.86 0.002
Gender 2,797


    Female

    Male
1.15 0.98, 1.36 0.094
Type of House 2,797


    Pucca

    Semi-pucca
0.93 0.76, 1.14 0.5
    Kutcha
0.72 0.55, 0.95 0.019
PSU Rural/Urban 2,797


    Rural

    Urban
1.49 1.24, 1.79 <0.001
Wealth Index 2,797


    Highest

    Higher
1.37 1.03, 1.82 0.033
    Middle
1.27 0.95, 1.71 0.10
    Lower
1.60 1.20, 2.15 0.002
    Lowest
2.69 1.99, 3.66 <0.001
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 2,805


    Normal

    severewasting
1.56 0.91, 2.63 0.10
age_gp 2,805


    1-2

    2-3
0.68 0.52, 0.89 0.005
    3-4
0.73 0.57, 0.95 0.017
    4-5
0.67 0.52, 0.87 0.002
Gender 2,805


    Female

    Male
1.15 0.98, 1.36 0.090
Type of House 2,805


    Pucca

    Semi-pucca
0.91 0.74, 1.12 0.4
    Kutcha
0.73 0.55, 0.95 0.020
PSU Rural/Urban 2,805


    Rural

    Urban
1.48 1.23, 1.78 <0.001
Wealth Index 2,805


    Highest

    Higher
1.38 1.04, 1.83 0.028
    Middle
1.29 0.97, 1.73 0.083
    Lower
1.67 1.25, 2.23 <0.001
    Lowest
2.85 2.11, 3.85 <0.001
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) 2,603 0.96 0.94, 0.98 <0.001
age_gp 2,603


    1-2

    2-3
0.78 0.59, 1.05 0.10
    3-4
0.77 0.58, 1.02 0.067
    4-5
0.74 0.56, 0.97 0.031
Gender 2,603


    Female

    Male
1.28 1.07, 1.52 0.006
Type of House 2,603


    Pucca

    Semi-pucca
0.92 0.74, 1.13 0.4
    Kutcha
0.73 0.55, 0.97 0.030
PSU Rural/Urban 2,603


    Rural

    Urban
1.56 1.29, 1.89 <0.001
Wealth Index 2,603


    Highest

    Higher
1.53 1.14, 2.07 0.005
    Middle
1.30 0.96, 1.76 0.091
    Lower
1.81 1.34, 2.45 <0.001
    Lowest
2.65 1.93, 3.65 <0.001
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) 2,603 0.92 0.88, 0.96 <0.001
age_gp 2,603


    1-2

    2-3
0.79 0.59, 1.06 0.11
    3-4
0.77 0.58, 1.03 0.076
    4-5
0.75 0.57, 1.00 0.048
Gender 2,603


    Female

    Male
1.27 1.07, 1.51 0.007
Type of House 2,603


    Pucca

    Semi-pucca
0.91 0.74, 1.13 0.4
    Kutcha
0.73 0.55, 0.96 0.028
PSU Rural/Urban 2,603


    Rural

    Urban
1.55 1.28, 1.88 <0.001
Wealth Index 2,603


    Highest

    Higher
1.51 1.12, 2.04 0.007
    Middle
1.28 0.95, 1.74 0.11
    Lower
1.77 1.31, 2.40 <0.001
    Lowest
2.61 1.91, 3.60 <0.001
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) 2,603 1.00 1.00, 1.00 0.006
age_gp 2,603


    1-2

    2-3
0.75 0.56, 1.01 0.055
    3-4
0.72 0.54, 0.95 0.021
    4-5
0.67 0.51, 0.89 0.005
Gender 2,603


    Female

    Male
1.26 1.06, 1.50 0.008
Type of House 2,603


    Pucca

    Semi-pucca
0.90 0.73, 1.12 0.3
    Kutcha
0.70 0.53, 0.93 0.015
PSU Rural/Urban 2,603


    Rural

    Urban
1.56 1.29, 1.89 <0.001
Wealth Index 2,603


    Highest

    Higher
1.50 1.11, 2.02 0.008
    Middle
1.27 0.94, 1.72 0.13
    Lower
1.75 1.30, 2.37 <0.001
    Lowest
2.57 1.87, 3.55 <0.001
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) 2,603 1.00 0.99, 1.00 0.047
age_gp 2,603


    1-2

    2-3
0.75 0.56, 1.00 0.053
    3-4
0.72 0.54, 0.95 0.020
    4-5
0.68 0.52, 0.90 0.006
Gender 2,603


    Female

    Male
1.26 1.06, 1.49 0.009
Type of House 2,603


    Pucca

    Semi-pucca
0.92 0.74, 1.13 0.4
    Kutcha
0.74 0.56, 0.98 0.037
PSU Rural/Urban 2,603


    Rural

    Urban
1.54 1.27, 1.86 <0.001
Wealth Index 2,603


    Highest

    Higher
1.53 1.14, 2.07 0.005
    Middle
1.30 0.96, 1.76 0.093
    Lower
1.81 1.34, 2.45 <0.001
    Lowest
2.73 1.99, 3.75 <0.001
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 = 1.81, 95% CI: 1.38–2.38, p < 0.001) and water tankers (OR = 1.70, 95% CI: 1.06–2.71, p = 0.026) were associated with higher odds of elevated blood lead levels.

  • Children with severe stunting (OR = 1.54, 95% CI: 1.17–2.01, p = 0.002) and severe underweight status (OR = 1.55, 95% CI: 1.12–2.12, p = 0.007) were associated with higher odds of elevated blood lead levels.

  • Iron deficiency (OR = 1.70, 95% CI: 1.15–2.50, p = 0.008) and any anaemia (OR = 1.25, 95% CI: 1.07–1.47, p = 0.005) were associated with higher odds of elevated blood lead levels.

  • Notably, the concurrent presence of both anaemia and iron deficiency amplified these odds nearly five-fold (OR = 4.72, 95% CI: 1.31–20.10, p = 0.023).

  • Consistent with the biomarker findings, higher daily dietary intakes of iron and zinc were protective, reducing the odds by 4% (OR = 0.96, 95% CI: 0.94–0.98, p < 0.001) and 8% (OR = 0.92, 95% CI: 0.88–0.96, 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 higher lower