Table 4. Hazard ratios with 95% confidence intervals of all lymphohaematopoietic cancers, all myeloid cancers, and AML according to benzene exposure among 24 917 Norwegian male offshore oil industry workers followed during 1999–2011.
|
Lymphohaematopoietic (n=112) |
Myeloid (n=21) |
AML (n=10) |
|||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Exposure metric | C | NC | HRa | HRb (95% CI) | C | NC | HRa | HRb (95% CI) | C | NC | HRa | HRb (95% CI) | |||
|
Cumulative (p.p.m.-years)c | |||||||||||||||
| Unexposed | 29 | 547 | 1.00 | 1.00 (reference) | 6 | 547 | 1.00 | 1.00 (reference) | 2 | 547 | 1.00 | 1.00 (reference) | |||
| T1 (<0.001–0.037) | 31 | 368 | 1.44 | 1.47 (0.87, 2.50) | 5 | 372 | 1.09 | 1.12 (0.31, 4.01) | 2 | 372 | 1.38 | 1.40 (0.18, 11) | |||
| T2 (>0.037–0.123) | 24 | 375 | 1.28 | 1.29 (0.74, 2.26) | 4 | 372 | 1.16 | 1.12 (0.30, 4.23) | 1 | 374 | 0.85 | 0.85 (0.08, 9.29) | |||
| T3 (0.124–0.948) | 28 | 371 | 1.55 | 1.61 (0.94, 2.76) | 6 | 370 | 1.98 | 2.24 (0.65, 7.71) | 5 | 368 | 4.49 | 4.85 (0.88, 27) | |||
| P trendb | 0.207 | 0.188 | 0.052 | ||||||||||||
|
Cumulative peak (>3 p.p.m.)c | |||||||||||||||
| Unexposed | 39 | 682 | 1.00 | 1.00 (reference) | 6 | 682 | 1.00 | 1.00 (reference) | 2 | 682 | 1.00 | 1.00 (reference) | |||
| Tertile 1 | 26 | 325 | 1.27 | 1.30 (0.77, 2.19) | 5 | 327 | 1.46 | 1.51 (0.44, 5.18) | 2 | 327 | 1.84 | 1.95 (0.27, 14) | |||
| Tertile 2 | 24 | 327 | 1.40 | 1.41 (0.83, 2.40) | 6 | 325 | 2.47 | 2.46 (0.75, 8.10) | 3 | 326 | 3.57 | 3.52 (0.61, 20) | |||
| Tertile 3 | 23 | 327 | 1.33 | 1.37 (0.80, 2.34) | 4 | 327 | 1.75 | 1.97 (0.51, 7.69) | 3 | 326 | 3.61 | 3.92 (0.59, 26) | |||
| P trendb | 0.326 | 0.330 | 0.166 | ||||||||||||
|
Duration (years exposed) | |||||||||||||||
| 0 | 29 | 547 | 1.00 | 1.00 (reference) | 6 | 547 | 1.00 | 1.00 (reference) | 2 | 547 | 1.00 | 1.00 (reference) | |||
| >0–5.49 | 31 | 395 | 1.35 | 1.38 (0.81, 2.35) | 5 | 395 | 1.02 | 1.07 (0.30, 3.80) | 3 | 395 | 1.97 | 2.04 (0.33, 13) | |||
| 5.5–12.9 | 27 | 362 | 1.53 | 1.56 (0.91, 2.66) | 6 | 362 | 1.82 | 1.80 (0.52, 6.24) | 4 | 362 | 3.33 | 3.39 (0.67, 17) | |||
| 13–33.5 | 25 | 357 | 1.42 | 1.44 (0.83, 2.52) | 4 | 357 | 1.41 | 1.47 (0.37, 5.88) | 1 | 357 | 0.96 | 0.97 (0.08, 11) | |||
| P trendb | 0.292 | 0.508 | 0.880 | ||||||||||||
|
Average intensity (p.p.m.)c | |||||||||||||||
| Unexposed | 29 | 547 | 1.00 | 1.00 (reference) | 6 | 547 | 1.00 | 1.00 (reference) | 2 | 547 | 1.00 | 1.00 (reference) | |||
| T1 (<0.001–0.007) | 30 | 369 | 1.47 | 1.47 (0.87, 2.50) | 2 | 375 | 0.50 | 0.45 (0.09, 2.31) | 1 | 373 | 0.77 | 0.76 (0.07, 8.67) | |||
| T2 (>0.007–0.013) | 25 | 374 | 1.30 | 1.32 (0.76, 2.31) | 8 | 368 | 2.26 | 2.41 (0.77, 7.53) | 3 | 371 | 2.46 | 2.51 (0.41, 15) | |||
| T3 (>0.013–0.040) | 28 | 371 | 1.50 | 1.57 (0.92, 2.66) | 5 | 371 | 1.42 | 1.66 (0.48, 5.74) | 4 | 370 | 3.21 | 3.47 (0.63, 19) | |||
| P trendb | 0.168 | 0.209 | 0.092 | ||||||||||||
|
Average peak (>3 p.p.m.)c | |||||||||||||||
| Unexposed | 39 | 682 | 1.00 | 1.00 (reference) | 6 | 682 | 1.00 | 1.00 (reference) | 2 | 682 | 1.00 | 1.00 (reference) | |||
| Tertile 1 | 27 | 324 | 1.48 | 1.50 (0.90, 2.50) | 6 | 326 | 2.09 | 2.09 (0.63, 6.86) | 2 | 327 | 2.11 | 2.17 (0.31, 15) | |||
| Tertile 2 | 24 | 327 | 1.32 | 1.33 (0.78, 2.26) | 4 | 327 | 1.49 | 1.53 (0.42, 5.58) | 2 | 327 | 2.16 | 2.21 (0.30, 16) | |||
| Tertile 3 | 22 | 328 | 1.19 | 1.23 (0.72, 2.10) | 5 | 326 | 1.91 | 2.19 (0.65, 7.36) | 4 | 325 | 4.50 | 4.87 (0.90, 26) | |||
| P trendb | 0.478 | 0.234 | 0.056 | ||||||||||||
Abbreviations: C=cases; CI=confidence interval; HR=hazard ratio; NC=non-cases; T=tertile.
a
Adjusted for age (as the timescale).
b
Adjusted for age (as the timescale); benzene exposure from other work (yes, no); and ever daily smoker (yes, no, unknown).
c
Categories were generated according to tertiles among exposed workers. Cut-points for estimated p.p.m. and p.p.m.-years refer to the full case-cohort set (112 C and 1661 NC).