Odds ratios and 95% confidence intervals from the studies included in the meta-analysis according to duration of exposure to chlorinated drinking water
| *Risk for both sexes obtained from a meta-analysis of men and women risk. †OR for the quartile of ≥10 daily cups of tap water consumption. ‡OR for the stratum of water consumption above the population median (1.4 litres). | |||||
| Case-control studies | |||||
| Cantor 98 | Never exposed | 1–19 years | 20–39 years | 40–59 years | ≥60 years |
| Men | 1.0 | 1.1 (0.8 to 1.3) | 1.3 (0.9 to 1.8) | 1.5 (0.95 to 2.3) | 1.9 (1.1 to 3.6) |
| Women | 1.0 | 0.9 (0.6 to 1.4) | 0.7 (0.3 to 1.3) | 0.7 (0.3 to 1.4) | 0.7 (0.2 to 2.4) |
| Both sexes | 1.0 | 1.0 (0.8 to 1.2) | 1.1 (0.8 to 1.4) | 1.2 (0.8 to 1.7) | 1.5 (0.9 to 2.6) |
| Koivusalo 98 | <15 years | 15–29 years | 30–44 years | ≥45 years | |
| Men | 1.0 | 1.07 (0.73 to 1.55) | 1.67 (1.01 to 2.78) | 2.32 (0.99 to 5.45) | |
| Women | 1.0 | 0.92 (0.49 to 1.72) | 1.19 (0.53 to 2.64) | 1.88 (0.54 to 6.57) | |
| Both sexes* | 1.03 (0.74 to 1.42) | 1.52 (1.0 to 2.33) | 2.2 (1.1 to 4.4) | ||
| King 96 | ≤9 years | 10–19 years | 20–34 years | ≥35 years | |
| Men | – | – | – | – | |
| Women | – | – | – | – | |
| Both sexes | 1.0 | 1.04 (0.71 to 1.53) | 1.15 (0.86 to 1.51) | 1.41 (1.09 to 1.81) | |
| McGeehin 93 | 0 years | 1–10 years | 11–20 years | 21–30 years | >30 years |
| Men | – | – | – | – | – |
| Women | – | – | – | – | – |
| Both sexes | 1.0 | 0.7 (0.4 to 1.3) | 1.4 (0.8 to 2.5) | 1.5 (0.8 to 2.9) | 1.8 (1.1 to 2.9) |
| Vena 93† | 0–49 years | 50–59 years | 60–67 years | 68–86 years | |
| Men | 2.89 (1.47 to 5.67) | 1.85 (0.96 to 3.57) | 2.27 (1.14 to 4.50) | 2.24 (1.05 to 4.74) | |
| Women | – | – | – | – | |
| Both sexes | – | – | – | – | |
| Cantor 87‡ | 0 years | 1–19 years | 20–39 years | 40–59 years | ≥60 years |
| Men | 1.0 | 1.1 (0.7 to 1.6) | 1.1 (0.7 to 1.5) | 1.2 (0.8 to 1.7) | 1.2 (0.7 to 2.1) |
| Women | 1.0 | 1.8 (0.8 to 3.7) | 1.5 (0.7 to 3.1) | 2.2 (1.0 to 4.8) | 3.2 (1.2 to 8.7) |
| Both sexes | 1.0 | 1.2 (0.9 to 1.7) | 1.1 (0.8 to 1.6) | 1.3 (0.9 to 1.9) | 1.4 (0.9 to 2.3) |
| Cohort studies | |||||
| Doyle 97 | 100% ground water | Mixed ground-surface water 2.27 (1.2 to 4.31) | 100% surface water 0.62 (0.15 to 2.63) | ||
| Women | 1.0 | 2.27 (1.2 to 4.31) | 0.62 (0.15 to 2.63) | ||
| Wilkins and Comstock 81 | Deep well users | Chlorinated surface water users | |||
| Men | 1.0 | 1.80 (0.8 to 4.75) | |||
| Women | 1.0 | 1.60 (0.54 to 6.32) | |||
| Both sexes* | 1.7 (0.8 to 3.5) | ||||