Table 5.
Association between colorectal cancer and shower/bath trihalomethane (THM) levels. Odds ratios (ORs) and 95% confidence intervals (CIs) among 1,702 cases and 3,269 controls.
| Exposure | All (n = 4,971) | Men (n = 2,793) | Women (n = 2,176)a | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Cases | Controls | ORb (95% CI) | Cases | Controls | ORb (95% CI) | Cases | Controls | ORb (95% CI) | |
| Total THMs (μg/L × min/day) | |||||||||
| < 60.7 | 550 | 701 | 1 | 363 | 444 | 1 | 185 | 257 | 1 |
| 60.7–158.7 | 382 | 867 | 0.72 (0.58, 0.89) | 244 | 420 | 0.76 (0.58, 0.99) | 138 | 447 | 0.67 (0.47, 0.97) |
| 158.7–336.7 | 329 | 920 | 0.60 (0.48, 0.76) | 203 | 416 | 0.68 (0.50, 0.92) | 126 | 504 | 0.54 (0.37, 0.80) |
| > 336.7 | 441 | 781 | 0.81 (0.63, 1.06) | 279 | 424 | 0.92 (0.65, 1.29) | 162 | 357 | 0.71 (0.46, 1.09) |
| p-Trendc | 0.121 | 0.426 | 0.141 | ||||||
| Chloroform (μg/L × min/day) | |||||||||
| < 26.1 | 550 | 701 | 1 | 361 | 435 | 1 | 188 | 266 | 1 |
| 26.7–72.5 | 444 | 804 | 0.85 (0.70, 1.03) | 284 | 405 | 0.90 (0.70, 1.16) | 159 | 399 | 0.82 (0.59, 1.13) |
| 72.5–143.5 | 373 | 861 | 0.65 (0.53, 0.81) | 237 | 445 | 0.68 (0.51, 0.89) | 136 | 416 | 0.68 (0.48, 0.97) |
| > 143.5 | 335 | 903 | 0.66 (0.52, 0.83) | 207 | 419 | 0.73 (0.54, 0.99) | 128 | 484 | 0.60 (0.41, 0.88) |
| p-Trendc | < 0.001 | 0.016 | 0.007 | ||||||
| Brominated THMs (μg/L × min/day) | |||||||||
| < 16.5 | 539 | 712 | 1 | 345 | 455 | 1 | 192 | 257 | 1 |
| 16.5–51.0 | 339 | 911 | 0.66 (0.53, 0.83) | 217 | 431 | 0.76 (0.57, 1.01) | 122 | 480 | 0.52 (0.36, 0.74) |
| 51.0–178.0 | 345 | 904 | 0.61 (0.47, 0.80) | 220 | 401 | 0.78 (0.56, 1.09) | 125 | 503 | 0.43 (0.28, 0.65) |
| > 178 | 479 | 742 | 0.90 (0.65, 1.25) | 307 | 417 | 1.25 (0.83, 1.89) | 172 | 325 | 0.55 (0.32, 0.95) |
| p-Trendc | 0.267 | 0.627 | 0.010 | ||||||
| aTwo female cases were excluded from the sex-stratified model because one category in education did not have observations among controls and was dropped from the model. bAdjusted for sex, age, geographical area, education, nonsteroidal antiinflammatory drug consumption, smoking, physical activity, and family history of colorectal cancer. The analysis excluded subjects with poor or questionable interviews and with known THM levels for < 70% of the exposure window (from age 18 to 2 years before the interview). cLinear trend p-value, derived from a likelihood-ratio test comparing a model with the categorical nitrate variable as an ordinal variable (0, 1, 2) with a model that excluded the variable. | |||||||||