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Table 3 Associations between wastewater impacted public drinking water in homogenous supplies and breast cancer.

From: Breast cancer risk and drinking water contaminated by wastewater: a case control study

  Cases Controls Adjusted OR (95% CI)a Adjusted OR (95% CI)b
Average annual excess nitrate-N concentration (mg/L)
0 to < .3 280 250 1.0 (referent) 1.0 (referent)
.3 to < .6 163 141 1.0 (0.7 – 1.3) 1.0 (0.7 – 1.3)
.6 to < .9 149 144 0.9 (0.6 – 1.2) 0.9 (0.6 – 1.2)
.9 to < 1.2 78 79 0.8 (0.5 – 1.2) 0.8 (0.5 – 1.2)
≥ 1.2 12 9 1.2 (0.5 – 2.9) 1.2 (0.5 – 3.1)
Sum of annual excess nitrate-N concentrations (mg/L)
0 to < .01 18 17 0.8 (0.4 – 1.6) 0.9 (0.4 – 1.9)
.01 to < .1 43 41 0.9 (0.5 – 1.4) 1.0 (0.6 – 1.7)
.1 to < 1 104 104 0.9 (0.6 – 1.2) 1.1 (0.8 – 1.5)
1 to < 10 390 344 1.0 (referent) 1.0 (referent)
≥ 10 127 117 1.0 (0.7 – 1.3) 0.9 (0.6 – 1.2)
Number of years exposed to excess nitrate-N > 1 mg/L
0 479 433 1.0 (referent) 1.0 (referent)
< 2 50 47 0.9 (0.6 – 1.4) 1.0 (0.6 – 1.5)
2 to < 4 87 69 1.1 (0.7 – 1.6) 1.0 (0.7 – 1.5)
4 to < 6 66 74 0.8 (0.5 – 1.2) 0.7 (0.5 – 1.1)
  1. a Adjusted for diagnosis/reference year, age at diagnosis/reference year, birth decade, study, vital status, previous breast cancer diagnosis, age at first birth, family history of breast cancer, and education.
  2. b Adjusted for variables in analysis [a] and years on Cape Cod and years on the Cape squared.