Table 2

ORs and 95% CIs for risk of cancers of the colon and rectum according to exposure to water factors, by sex

Water factora levelMalesFemalesPc
CasesControlsORb (CI)CasesControlsORb (CI)
Colon cancer
Chlorinated (yr)
0–91012701.001091351.00
10–1941841.70 (1.07–2.68)25670.55 (0.32–0.94)
20–341072701.33 (0.96–1.86)841580.85 (0.58–1.24)
≥351723351.53 (1.13–2.09)1132050.74 (0.52–1.05)0.003
THM ≥50 μg/liter (yr)
0–91664111.001612301.00
10–191383181.13 (0.86–1.50)961930.77 (0.55–1.07)
20–34851801.31 (0.94–1.81)531150.63 (0.42–0.93)
≥3532501.68 (1.02–2.76)21271.02 (0.55–1.90)0.030
THM ≥75 μg/liter (yr)
0–92235451.001933191.00
10–191282981.12 (0.85–1.46)951820.91 (0.66–1.25)
20–3444821.49 (0.99–2.26)27440.92 (0.54–1.56)
≥3526342.10 (1.21–3.66)16201.20 (0.60–2.42)0.323
THM-years (quartiles) (μg/liter-yr)
1 (0–583)992571.001041221.00
2 (584–1505)962251.30 (0.92–1.84)751550.69 (0.47–1.03)
3 (1506–1956)942401.11 (0.78–1.57)751440.73 (0.49–1.08)
4 (1957–6425)1322371.74 (1.25–2.43)771440.65 (0.44–0.97)0.002
THM-years (continuous) 1000 μg/liter-yr1.62d1.47d1.17 (1.06–1.29)1.39d1.51d0.91 (0.81–1.03)0.002
Rectal cancer
Chlorinated (yr)
0–91272701.00701351.00
10–1933841.10 (0.69–1.76)22670.71 (0.40–1.27)
20–341022700.98 (0.71–1.36)601580.89 (0.58–1.37)
≥351313350.97 (0.72–1.32)1022051.04 (0.71–1.53)0.578
THM ≥50 μg/liter (yr)
0–91814111.001222301.00
10–191183180.94 (0.71–1.25)761930.78 (0.55–1.11)
20–34771801.07 (0.77–1.49)451150.73 (0.48–1.11)
≥3517500.82 (0.45–1.48)11270.71 (0.33–1.50)0.546
THM ≥75 μg/liter (yr)
0–92385451.001473191.00
10–191062980.89 (0.67–1.18)801821.00 (0.71–1.40)
20–3436821.08 (0.70–1.68)18440.81 (0.44–1.47)
≥3513340.96 (0.49–1.89)9200.89 (0.39–2.02)0.777
THM-years (quartiles) (μg/liter-yr)
1 (0–583)1182571.00721221.00
2 (584–1505)992251.20 (0.86–1.67)601550.78 (0.51–1.19)
3 (1506–1956)832400.90 (0.63–1.27)681440.93 (0.61–1.42)
4 (1957–6425)932371.03 (0.73–1.44)541440.69 (0.44–1.06)0.186
THM-years (continuous) 1000 μg/liter-yr1.37d1.47d0.98 (0.88–1.08)1.42d1.51d0.94 (0.82–1.08)0.648
  • a Calculated over the 40 years before the interview for subjects with ≥30 years of known exposure information.

  • b 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.

  • c P for interaction with sex.

  • d Mean values.