Table 3.
Nitrate intake from drinking water (quintiles) and breast cancer riska
| Median (mg/2L) | Range (mg/2L) | Cases | Person-years | HR (95% CI)b | ||
|---|---|---|---|---|---|---|
| Water nitrate intake | ||||||
| Q1 | 1.6 | 0 – 2.8 | 253 | 57,345 | 1.0 (reference) | |
| Q2 | 4.1 | 3.0 – 7.9 | 255 | 56,101 | 1.07 (0.89 – 1.28) | |
| Q3 | 9.4 | 8.0 – 14.1 | 244 | 57,163 | 0.96 (0.80 – 1.16) | |
| Q4 | 21.2 | 14.3 – 33.3 | 250 | 54,775 | 1.05 (0.88 – 1.27) | |
| Q5 | 57.8 | 33.5 – 145.3 | 286 | 57,902 | 1.14 (0.95 – 1.36) | |
| ptrend | 0.11 | |||||
| Private well users | N/A | N/A | 463 | 96,326 | 1.14 (0.97 – 1.34) | |
Analysis includes 20,147 women (15,151 public water supply users and 4,996 private well users) who responded to the 1989 follow-up survey, had used public water private well water supply for more than 10 years, and lived in communities which were served by one water source and had nitrate measurement data.
Adjusted for age (continuous), total energy intake (continuous), BMI (continuous), WHR (continuous), education (<high school, high school, >high school), smoking (never, previous, current), physical activity level (low, moderate, high), family history of breast cancer (yes/no), estrogen use (never, ever), and total intakes of folate, vitamin C and E and flavonoids, intakes of cruciferae and red meat.