Table 3 Basic data about the investigated pulp mill workers employed at any time between 1970 and 2000, by exposure to irritant gases
All | Unexposed | Exposed but no gassings | Few episodes of gassings | Frequent gassings | |
|---|---|---|---|---|---|
(N = 3,060) | (N = 1,584) | (N = 259) | (N = 866) | (N = 351) | |
Mean age at follow-up, yrs (SD) | 46.9 (12.4) | 45.9 (12.7) | 45.5 (11.5) | 47.6 (12.3)* | 51.2 (11.3)*** |
Atopy, % (N) | 18.4% (564) | 17.6% (278) | 17.0% (44) | 20.2% (175) | 19.1% (67) |
Physician-diagnosed asthma, % (N) | 7.1% (216) | 5.4% (85) | 4.3% (11) | 7.0% (61) | 16.8% (59)*** |
Adult chronic bronchitis, % (N) | 5.4% (164) | 3.2% (50) | 2.7% (7) | 6.0% (52)** | 15.7% (55)*** |
Pack-years among current and former smokers, mean (SD) | 14.7 (12.4) | 14.1 (12.3) | 14.1 (12.0) | 14.9 (11.8) | 17.1 (13.9)** |
Current smokers, % (N) | 12.9% (395) | 13.6% (216) | 13.1% (34) | 11.8% (102) | 12.3% (43) |
Former smokers, % (N) | 34.8% (1,064) | 32.8% (519) | 28.2% (73) | 37.8% (327)* | 41.3% (145)** |
Never-smokers, % (N) | 51.0% (1,560) | 51.8% (820) | 57.9% (150) | 49.8% (431) | 45.3% (159)* |
Person-years at risk, sum | 57,977 | 27,802 | 5,064 | 17,333 | 7,778 |
Person-years at risk, mean (SD) | 19.1 (9.1) | 17.7 (9.1) | 19.6 (8.6)** | 20.2 (8.9)*** | 22.9 (8.4)*** |