Duration, cumulative exposure, and probability of occupational exposure to formaldehyde in relation to risk of nasopharyngeal cancer3-151
| Exposure to formaldehyde | Probability of exposure | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Possible, probable or definite | Probable or definite | Definite | |||||||||
| Controls n | Cases n | OR3-152 (95% CI) | Controls n | Cases n | OR3-152 (95% CI) | Controls n | Cases n | OR3-152 (95% CI) | |||
| Ever | 79 | 61 | 1.6 (1.0 to 2.8) | 30 | 27 | 2.1 (1.1 to 4.2) | 2 | 10 | 13.33-150 (2.5 to 70) | ||
| Duration (y): | |||||||||||
| 1 to 5 | 41 | 16 | 0.9 (0.4 to 2.1) | 17 | 12 | 2.0 (0.8 to 5.0) | 1 | 5 | — | ||
| 6 to 17 | 19 | 20 | 1.9 (0.9 to 4.4) | 5 | 9 | 3.3 (0.9 to 11.8) | 1 | 2 | — | ||
| >18 | 19 | 25 | 2.7 (1.2 to 6.0) | 8 | 6 | 1.6 (0.5 to 5.6) | 0 | 3 | — | ||
| Trend test | p=0.014 | p=0.069 | p<0.001 | ||||||||
| Cumulative exposure (ppm-years): | |||||||||||
| 0.05–0.40 | 40 | 15 | 0.9 (0.4 to 2.0) | 16 | 12 | 1.9 (0.7 to 4.9) | 1 | 4 | — | ||
| >0.4–1.10 | 20 | 22 | 1.8 (0.8 to 4.1) | 5 | 7 | 2.6 (0.7 to 9.5) | 1 | 2 | — | ||
| >1.10 | 19 | 24 | 3.0 (1.3 to 6.6) | 9 | 8 | 2.2 (0.7 to 7.0) | 0 | 4 | — | ||
| Trend test | p=0.033 | p=0.13 | p<0.001 | ||||||||