Table 3 Workplace silica exposure and bladder cancer in men from the NECSS, 1994–1997
Silica exposure groups | Cases | Controls | Minimal a | Full b | ||
|---|---|---|---|---|---|---|
N | % | N | % | OR (95% CI) | OR (95% CI) | |
Ever exposed to silica | ||||||
Never | 404 | 20.0 | 929 | 46.0 | 1.00 | 1.00 |
Ever | 254 | 12.6 | 431 | 21.4 | 1.27 (1.00–1.61) | 1.20 (0.95–1.51) |
≥ 20 years ago | 57 | 88 | 1.29 (0.89–1.88) | 1.14 (0.79–1.66) | ||
≥ 40 years ago | 146 | 254 | 1.21 (0.94–1.55) | 1.06 (0.82–1.38) | ||
Highest attained concentration of exposure to silica | ||||||
Unexposed | 404 | 20.0 | 929 | 46.0 | 1.00 | 1.00 |
Low | 218 | 10.8 | 369 | 18.3 | 1.23 (0.99–1.53) | 1.24 (0.98–1.58) |
Medium/ High | 36 | 1.8 | 62 | 3.1 | 1.14 (0.73–1.79) | 0.96 (0.60–1.54) |
p-trend | 0.05 | 0.13 | ||||
Highest attained frequency of exposure to silica | ||||||
Unexposed | 404 | 20.0 | 929 | 46.0 | 1.00 | 1.00 |
< 5% | 18 | 0.9 | 51 | 2.5 | 0.82 (0.46–1.46) | 0.81 (0.45–1.46) |
5–30% | 160 | 7.9 | 274 | 13.6 | 1.21 (0.95–1.55) | 1.26 (0.97–1.64) |
≥ 30% | 76 | 3.8 | 106 | 5.3 | 1.38 (0.99–1.93) | 1.22 (0.84–1.77) |
p-trend | 0.03 | 0.09 | ||||
Duration of exposure to silica (years) | ||||||
Unexposed | 404 | 20.0 | 929 | 46.0 | 1.00 | 1.00 |
< 7 | 78 | 3.9 | 134 | 6.6 | 1.20 (0.87–1.64) | 1.17 (0.84–1.63) |
7- < 27 | 67 | 3.3 | 118 | 5.9 | 1.12 (0.80–1.57) | 1.02 (0.73–1.43) |
≥ 27 | 99 | 4.9 | 164 | 8.1 | 1.29 (0.96–1.74) | 1.41 (1.01–1.98) |
Unknown | 10 | 0.5 | 15 | 0.7 | ||
p-trend | 0.07 | 0.16 | ||||
Duration of exposure at low concentrations of silica (years) | ||||||
Unexposed | 421 | 20.9 | 968 | 48.0 | 1.00 | 1.00 |
< 7 | 75 | 3.7 | 124 | 6.1 | 1.21 (0.88–1.68) | 1.20 (0.86–1.68) |
7 - < 27 | 69 | 3.4 | 123 | 6.1 | 1.14 (0.82–1.59) | 1.09 (0.77–1.55) |
≥ 27 | 83 | 4.1 | 132 | 6.5 | 1.38 (1.00–1.91) | 1.52 (1.07–2.14) |
Unknown | 10 | 0.5 | 13 | 0.6 | ||
p-trend | 0.03 | 0.07 | ||||
Duration of exposure at medium/high concentrations of silica (years) | ||||||
Unexposed | 622 | 30.8 | 1298 | 64.3 | 1.00 | 1.00 |
< 7 | 18 | 0.9 | 30 | 1.5 | 1.20 (0.65–2.22) | 1.07 (0.57–2.00) |
≥ 7 | 18 | 0.9 | 30 | 1.5 | 1.00 (0.54–1.88) | 0.76 (0.39–1.46) |
Unknown | 0 | 0.0 | 2 | 0.1 | ||
p-trend | 0.85 | 0.67 | ||||
Cumulative exposure to silica | ||||||
Unexposed | 404 | 20.0 | 929 | 46.0 | 1.00 | 1.00 |
Lowest tertile | 85 | 4.2 | 132 | 6.5 | 1.26 (0.92–1.72) | 1.24 (0.90–1.71) |
Middle tertile | 66 | 3.3 | 140 | 6.9 | 1.02 (0.73–1.42) | 1.03 (0.73–1.46) |
Highest tertile | 93 | 4.6 | 144 | 7.1 | 1.35 (0.99–1.83) | 1.29 (0.92–1.81) |
Unknown | 10 | 0.5 | 15 | 0.7 | ||
p-trend | 0.08 | 0.18 | ||||