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) |