Table 3

ORs and 95% CIs for risk of cancers of the colon and rectum associated with homogeneous exposure to water source characteristics for 30 or more of the 40 years before the study, by sex

Water factor levelMalesFemales
CasesControlsORa (CI)CasesControlsORa (CI)
Colon cancer
Source
Ground982541.001061281.00
Chlorinated surface2314721.49 (1.10–2.00)1661970.79 (0.56–1.10)
THM level
0–24 μg/liter1052761.001101311.00
25–7447851.53 (0.99–2.38)23640.46 (0.26–0.81)
≥7537651.87 (1.15–3.05)23300.92 (0.49–1.71)
P = 0.005P = 0.211
Rectal cancer
Source
Ground1182541.00671281.00
Chlorinated surface1774720.99 (0.74–1.33)1451971.09 (0.75–1.57)
THM level
0–24 μg/liter1192761.00721311.00
25–7441851.27 (0.81–2.00)20640.62 (0.34–1.13)
≥7522650.98 (0.56–1.72)12300.72 (0.34–1.53)
P = 0.746P = 0.180
  • a OR (95% CI) for colon cancer adjusted for age; sex; education; body mass index; and intake of energy, cholesterol, calcium, alcohol, and coffee. OR (95% CI) for rectal cancer adjusted for age; sex; education; body mass index; previous medical conditions; and intake of energy, cholesterol, calcium, and coffee.