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Table 5 Crude and adjusted* odds ratio of preterm birth comparing above versus below the median of environmental exposure stratified by census tract-level socioeconomic status (SES) in Fresno County, 2009–2012 (N = 53,843)

From: Environmental pollution and social factors as contributors to preterm birth in Fresno County

Environmental Exposure Low SES High SES
< 37 weeks ≥37 weeks    < 37 weeks ≥37 weeks   
N (%) N (%) cOR (95% CI) aOR* (95% CI) N (%) N (%) cOR (95% CI) aOR* (95% CI)
Sample 2455 24,998    2105 24,285   
Exposures Score
    < 50th 924 (37.6) 10,360 (41.4) Reference Reference 1172 (55.7) 14,101 (58.1) Reference Reference
    ≥ 50th 1531 (62.4) 14,638 (58.6) 1.16 (1.07, 1.25) 1.16 (1.06, 1.25) 933 (44.3) 10,184 (41.9) 1.09 (1.00, 1.19) 1.07 (0.98, 1.17)
 Ozone
    < 50th 1481 (60.4) 15,063 (60.3) Reference Reference 777 (36.9) 8752 (36.0) Reference Reference
    ≥ 50th 974 (39.7) 9935 (39.7) 1.00 (0.92, 1.08) 1.00 (0.92, 1.08) 1295 (61.5) 14,916 (61.4) 0.98 (0.90, 1.07) 0.99 (0.90, 1.08)
 Pesticides
    < 50th 1019 (41.5) 9872 (39.5) Reference Reference 1244 (59.1) 14,691 (60.5) Reference Reference
    ≥ 50th 1436 (58.5) 15,126 (60.5) 0.93 (0.86, 1.00) 0.92 (0.85, 1.00) 861 (40.9) 9594 (39.5) 1.05 (0.97, 1.15) 1.05 (0.97, 1.15)
 PM2.5
    < 50th 592 (24.1) 6434 (25.7) Reference Reference 1425 (67.7) 17,259 (71.1) Reference Reference
    ≥ 50th 1736 (70.7) 17,286 (69.2) 1.08 (0.99, 1.19) 1.07 (0.98, 1.18) 650 (30.9) 6492 (26.7) 1.19 (1.09, 1.31) 1.15 (1.05, 1.26)
 Diesel PM
    < 50th 1096 (44.6) 12,166 (48.7) Reference Reference 1051 (49.9) 12,587 (51.8) Reference Reference
    ≥ 50th 1359 (55.4) 12,832 (51.3) 1.16 (1.07, 1.25) 1.16 (1.07, 1.25) 1054 (50.1) 11,698 (48.2) 1.07 (0.98, 1.17) 1.04 (0.96, 1.14)
 Toxic Release
    < 50th 735 (29.9) 8106 (32.4) Reference Reference 1315 (62.5) 16,391 (67.5) Reference Reference
    ≥ 50th 1720 (70.1) 16,892 (67.6) 1.11 (1.02, 1.21) 1.11 (1.02, 1.22) 790 (37.5) 7894 (32.5) 1.22 (1.12, 1.34) 1.18 (1.08, 1.29)
 Traffic
    < 50th 1240 (50.5) 13,288 (52.9) Reference Reference 972 (46.2) 11,579 (47.7) Reference Reference
    ≥ 50th 1215 (49.5) 11,770 (47.1) 1.09 (1.01, 1.18) 1.09 (1.01, 1.18) 1133 (53.8) 12,706 (52.3) 1.05 (0.97, 1.15) 1.03 (0.95, 1.13)
 Drinking Water
    < 50th 143 (5.8) 1863 (7.5) Reference Reference 402 (19.1) 4713 (19.4) Reference Reference
    ≥ 50th 2312 (94.2) 23,135 (92.6) 1.27 (1.08, 1.51) 1.29 (1.09, 1.52) 1703 (80.90 19,572 (80.6) 1.02 (0.91, 1.14) 1.00 (0.90, 1.12)
  Arsenic
    < 50th 234 (9.5) 2467 (9.9) Reference Reference 493 (23.4) 6230 (25.7) Reference Reference
    ≥ 50th 2221 (90.5) 22,531 (90.1) 1.04 (0.91, 1.19) 1.01 (0.88, 1.16) 1612 (76.6) 18,055 (74.4) 1.12 (1.01, 1.24) 1.09 (0.99, 1.21)
  Cadmium
    < 50th 0 (0.0) 0 (0.0) Reference Reference 0 (0.0) 0 (0.0) Reference Reference
    ≥ 50th 2455 (100.0) 24,998 (100.0) NC NC 2105 (100.0) 24,285 (100.0) NC NC
  1,2-Dibromo-3-chloropropane (DBCP)
    < 50th 979 (39.9) 10,100 (40.4) Reference Reference 604 (28.7) 6924 (28.5) Reference Reference
    ≥ 50th 1476 (60.1) 14,898 (59.5) 1.02 (0.94, 1.11) 1.02 (0.94, 1.10) 1472 (69.9) 16,834 (69.3) 1.00 (0.91, 1.10) 1.00 (0.91, 1.10)
  Hexavalent Chromium
    < 50th 0 (0.0) 0 (0.0) Reference Reference 0 (0.0) 0 (0.0) Reference Reference
    ≥ 50th 2147 (87.5) 21,281 (85.1) NC NC 2105 (100.0) 24,285 (100.0) NC NC
  Lead
    < 50th 0 (0.0) 0 (0.0) Reference Reference 0 (0.0) 0 (0.0) Reference Reference
    ≥ 50th 2455 (100.0) 24,998 (100.0) NC NC 2105 (100.0) 24,285 (100.0) NC NC
  Nitrate
    < 50th 1019 (41.5) 10,330 (41.3) Reference Reference 1226 (58.2) 14,410 (59.3) Reference Reference
    ≥ 50th 1436 (58.5) 14,668 (58.7) 0.99 (0.92, 1.08) 0.99 (0.92, 1.07) 879 (41.8) 9875 (40.7) 1.04 (0.96, 1.14) 1.03 (0.94, 1.12)
  Perchlorate
    < 50th 0 (0.0) 0 (0.0) Reference Reference 0 (0.0) 0 (0.0) Reference Reference
    ≥ 50th 2455 (100.0) 24,998 (100.0) NC NC 2105 (100.0) 24,285 (100.0) NC NC
  Trichloroethylene (TCE)
    < 50th 1036 (42.2) 11,114 (44.5) Reference Reference 1182 (56.2) 13,607 (56.0) Reference Reference
    ≥ 50th 1419 (57.8) 13,884 (55.5) 1.09 (1.00, 1.18) 1.07 (1.00, 1.17) 923 (43.9) 10,678 (44.0) 1.00 (0.91, 1.09) 0.99 (0.91, 1.08)
  Trihalomethane (THM)
    < 50th 1145 (46.6) 11,838 (47.4) Reference Reference 859 (40.8) 9593 (39.5) Reference Reference
    ≥ 50th 1310 (53.4) 13,160 (52.6) 1.03 (0.95, 1.11) 1.01 (0.93, 1.09) 1246 (59.2) 14,692 (60.5) 0.95 (0.87, 1.04) 0.96 (0.88, 1.04)
  Uranium
    < 50th 487 (19.8) 5535 (22.1) Reference Reference 294 (14.0) 3801 (15.7) Reference Reference
    ≥ 50th 1968 (80.2) 19,463 (77.9) 1.15 (1.04, 1.27) 1.14 (1.03, 1.25) 1679 (79.8) 18,9488 (78.0) 1.13 (1.00, 1.28) 1.12 (0.99, 1.27)
  Maximum Contaminant Level (MCL)Violations
    < 50th 1030 (42.0) 10,577 (42.3) Reference Reference 1207 (57.3) 13,998 (57.6) Reference Reference
    ≥ 50th 1425 (58.0) 14,4211 (57.7) 1.01 (0.94, 1.10) 1.00 (0.92, 1.09) 898 (42.7) 10,287 (42.4) 1.01 (0.93, 1.10) 1.00 (0.92, 1.09)
  Total coliform rule (TCR) Violations
    < 50th 0 (0.0) 0 (0.0) Reference Reference 0 (0.0) 0 (0.0) Reference Reference
    ≥ 50th 2455 (100.0) 24,998 (100.0) NC NC 2105 (100.0) 24,285 (100.0) NC NC
Environmental Effects Score
    < 50th 1036 (42.2) 10,073 (40.3) Reference Reference 1254 (59.6) 14,381 (59.2) Reference Reference
    ≥ 50th 1419 (57.8) 14,925 (59.7) 0.93 (0.86, 1.01) 0.92 (0.85, 1.00) 851 (40.4) 9904 (40.8) 0.99 (0.90, 1.08) 0.98 (0.89, 1.07)
 Cleanup Sites
    < 50th 1168 (47.6) 11,805 (47.2) Reference Reference 1139 (54.1) 12,799 (52.7) Reference Reference
    ≥ 50th 1287 (52.4) 13,193 (52.8) 0.99 (0.91, 1.07) 0.97 (0.90, 1.05) 966 (45.9) 11,486 (47.3) 0.95 (0.87, 1.03) 0.95 (0.87, 1.04)
 Groundwater Threats
    < 50th 973 (39.6) 9545 (38.2) Reference Reference 1290 (61.3) 15,062 (62.0) Reference Reference
    ≥ 50th 1482 (60.4) 15,453 (61.8) 0.95 (0.87, 1.03) 0.93 (0.86, 1.01) 815 (38.7) 9223 (38.) 1.03 (0.94, 1.12) 1.02 (0.94, 1.12)
 Hazardous Waste
    < 50th 1023 (41.7) 10,195 (40.8) Reference Reference 1240 (58.9) 14,430 (59.4) Reference Reference
    ≥ 50th 1432 (58.3) 14,803 (59.2) 0.97 (0.89, 1.05) 0.98 (0.90, 1.06) 865 (41.1) 9855 (40.6) 1.02 (0.93, 1.11) 0.99 (0.91, 1.09)
 Impaired Water Bodies
    < 50th 0 (0.0) 0 (0.0) Reference Reference 0 (0.0) 0 (0.0) Reference Reference
    ≥ 50th 2455 (100.0) 24,998 (100.0) NC NC 2105 (100.0) 24,285 (100.0) NC NC
 Solid Waste
    < 50th 0 (0.0) 0 (0.0) Reference Reference 0 (0.0) 0 (0.0) Reference Reference
    ≥ 50th 2455 (100.0) 24,998 (100.0) NC NC 2105 (100.0) 24,285 (100.0) NC NC
Pollution Burden Score
    < 50th 827 (33.7) 8615 (35.5) Reference Reference 1380 (65.6) 16,068 (66.2) Reference Reference
    ≥ 50th 1628 (66.3) 16,383 (65.5) 1.03 (0.95, 1.12) 1.04 (0.96, 1.13) 725 (34.4) 8217 (33.8) 1.03 (0.94, 1.12) 1.03 (0.93, 1.11)
  1. NC Not Calculated, cOR crude odds ratio, aOR adjusted odds ratio
  2. *Adjusted for maternal race/ethnicity, age, education, payment for delivery
  3. SES defined as “Socioeconomic Factors” score from the CalEnviroScreen, which includes the following variables derived from the US Census American Community Survey: educational attainment, linguistic isolation (households where no one over 14 years of age speaks English very well), poverty and unemployment