Table 2.
Demographic characteristics of controls and bladder and lung cancer cases
| Controls |
Bladder cancer |
Lung cancer |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| N | (%) | N | (%) | OR* | (95% CI) | N | (%) | OR* | (95% CI) | |
| Total | 640 | (100) | 232 | (100) | 306 | (100) | ||||
| Sex | ||||||||||
| Female | 209 | (32.7) | 62 | (26.7) | 91 | (29.7) | ||||
| Male | 431 | (67.3) | 170 | (73.3) | 215 | (70.3) | ||||
| Age (years) | ||||||||||
| 70+ | 269 | (42.0) | 94 | (40.5) | 112 | (36.6) | ||||
| 60–69 | 193 | (30.2) | 76 | (32.8) | 111 | (36.3) | ||||
| 50–59 | 132 | (20.6) | 39 | (16.8) | 69 | (22.5) | ||||
| 40–49 | 39 | (6.1) | 23 | (9.9) | 10 | (3.3) | ||||
| 30–39 | 7 | (1.1) | 0 | (0) | 4 | (1.3) | ||||
| Race | ||||||||||
| Other | 195 | (30.5) | 35 | (15.1) | 1.00 | 70 | (22.9) | 1.00 | ||
| European | 445 | (69.5) | 197 | (84.9) | 2.47 | (1.67 to 3.64) | 236 | (77.1) | 1.48 | (1.08 to 2.02) |
| Mining work | ||||||||||
| No | 498 | (77.8) | 173 | (74.6) | 1.00 | 241 | (78.8) | 1.00 | ||
| Yes | 142 | (22.2) | 59 | (25.4) | 1.20 | (0.84 to 1.70) | 65 | (21.2) | 0.95 | (0.68 to 1.32) |
| Body-mass index >30 kg/m2 | ||||||||||
| No | 518 | (80.9) | 191 | (82.3) | 1.00 | 269 | (87.9) | 1.00 | ||
| Yes | 122 | (19.1) | 41 | (17.7) | 0.91 | (0.62 to 1.35) | 37 | (12.1) | 0.58 | (0.39 to 0.87) |
| Smoking | ||||||||||
| Never | 242 | (37.8) | 65 | (28.0) | 1.00 | 59 | (19.3) | 1.00 | ||
| Ever | 398 | (62.2) | 167 | (72.0) | 1.56 | (1.13 to 2.17) | 247 | (80.7) | 2.55 | (1.85 to 3.51) |
| Socioeconomic status (tertiles) | ||||||||||
| Low | 231 | (36.1) | 73 | (31.5) | 1.00 | 126 | (41.2) | 1.00 | ||
| Medium | 203 | (31.7) | 66 | (28.4) | 1.03 | (0.70 to 1.51) | 103 | (33.7) | 0.93 | (0.67 to 1.28) |
| High | 206 | (32.2) | 93 | (40.1) | 1.43 | (1.00 to 2.04) | 77 | (25.2) | 0.69 | (0.49 to 0.96) |
| Water arsenic (µg/L) (highest one year)† | ||||||||||
| 0–59 | 138 | (21.6) | 23 | (9.9) | 1.00 | 48 | (15.7) | 1.00 | ||
| 60–199 | 193 | (30.2) | 27 | (11.6) | 0.84 | (0.46 to 1.52) | 52 | (17.0) | 0.77 | (0.49 to 1.21) |
| 200–799 | 144 | (22.5) | 60 | (25.9) | 2.50 | (1.48 to 4.22) | 69 | (22.6) | 1.38 | (0.89 to 2.13) |
| ≥ 800 | 165 | (25.8) | 122 | (52.6) | 4.44 | (2.75 to 7.15) | 137 | (44.8) | 2.39 | (1.61 to 3.54) |
| Drinking water intake (L/day)‡ | ||||||||||
| Current | 1.66 | (±0.91) | 2.04 | (±1.14) | p<0.001 | 1.84 ±1.02 | p=0.04 | |||
| 20 years ago | 1.80 | (±1.14) | 1.97 | (±1.22) | p=0.03 | 1.94 ±1.05 | p=0.02 | |||
*
Unadjusted odds ratios (OR) comparing bladder or lung cancer cases to controls. Odds ratios are not reported for age and sex since subjects were frequency matched on these factors.
†
These category cut-off points were chosen so each category includes the highest arsenic water concentration of each of the four largest cities in the study area: Arica (0–59 µg/L), Iquique 60–199 µg/L), Calama (200–799 µg/L), and Antofagasta ≥ 800 µg/L.
‡
Means, standard deviations, and p-values comparing bladder or lung cancer cases to controls.