Table 3.
Lung cancer risk associated with exposure to endotoxins
| Work environment group* | |||||||||||||||
| Total exposed to endotoxins | Weakly exposed† | Highly exposed ‡ | |||||||||||||
| Cases | Controls | OR§ | 95% Cl | ptrend | Cases | Controls | OR§ | 95% Cl | ptrend | Cases | Controls | OR§ | 95% Cl | ptrend | |
| N | N | N | N | N | N | ||||||||||
| Exposure to endotoxins | |||||||||||||||
| Never¶ | 2461 | 2895 | 1.00 | Reference | 2461 | 2895 | 1.00 | Reference | 2461 | 2895 | 1.00 | Reference | |||
| Ever** | 465 | 660 | 0.8 | (0.66 to 0.95) | 306 | 310 | 1.09 | (0.87 to 1.36) | 151 | 336 | 0.51 | (0.4 to 0.67) | |||
| Duration of exposure (years) | |||||||||||||||
| ≤6 | 179 | 185 | 1.03 | (0.78 to 1.36) | 129 | 120 | 1.24 | (0.9 to 1.73) | 50 | 64 | 0.66 | (0.41 to 1.08) | |||
| >6–14 | 111 | 150 | 0.97 | (0.7 to 1.34) | 72 | 67 | 1.35 | (0.87 to 2.09) | 33 | 80 | 0.6 | (0.36 to 0.99) | |||
| >14–34 | 86 | 160 | 0.58 | (0.41 to 0.81) | 58 | 79 | 0.67 | (0.43 to 1.04) | 27 | 77 | 0.45 | (0.25 to 0.81) | |||
| >34 | 85 | 165 | 0.57 | (0.4 to 0.82) | 0.0002 | 44 | 44 | 1.01 | (0.57 to 1.80) | 40 | 115 | 0.41 | (0.25 to 0.68) | <0.0001 | |
| Missing | 4 | 3 | 1 | ||||||||||||
| Cumulative exposure (UE*years)†† | |||||||||||||||
| Quartile 1 | 169 | 165 | 1.23 | (0.92 to 1.63) | 81 | 84 | 1.11 | (0.75 to 1.66) | 51 | 87 | 0.55 | (0.35 to 0.88) | |||
| Quartile 2 | 148 | 168 | 0.85 | (0.63 to 1.14) | 75 | 71 | 1.17 | (0.77 to 1.76) | 43 | 79 | 0.82 | (0.51 to 1.34) | |||
| Quartile 3 | 87 | 162 | 0.63 | (0.44 to 0.90) | 81 | 78 | 1.19 | (0.78 to 1.81) | 29 | 85 | 0.42 | (0.24 to 0.72) | |||
| Quartile 4 | 57 | 164 | 0.42 | (0.28 to 0.63) | 0.01 | 66 | 77 | 0.81 | (0.51 to 1.27) | 0.87 | 27 | 84 | 0.37 | (0.21 to 0.65) | <0.0001 |
| Missing | 4 | 1 | 3 | 1 | 1 | ||||||||||
| Time since cessation of exposure (years) | |||||||||||||||
| ≤5 | 72 | 172 | 0.6 | (0.41 to 0.86) | 46 | 71 | 0.81 | (0.51 to 1.31) | 25 | 98 | 0.38 | (0.21 to 0.69) | |||
| >5–21 | 100 | 162 | 0.7 | (0.51 to 0.99) | 66 | 78 | 0.98 | (0.63 to 1.52) | 33 | 77 | 0.47 | (0.27 to 0.82) | |||
| >21–39 | 148 | 167 | 0.91 | (0.67 to 1.22) | 106 | 99 | 1.1 | (0.76 to 1.58) | 39 | 66 | 0.62 | (0.37 to 1.04) | |||
| >39 | 142 | 159 | 0.95 | (0.69 to 1.3) | 0.18 | 86 | 62 | 1.4 | (0.91 to 2.15) | 0.2 | 53 | 95 | 0.61 | (0.38 to 0.94) | |
| Missing | 3 | 2 | 1 | 0.0002 | |||||||||||
*Work environment groups were classified into those weakly and highly exposed to endotoxins with a threshold of 1000 UE/m3; 22 subjects had both low and high endotoxin exposure jobs and were excluded from the stratified analysis.
†Weakly exposed group included cultivation, agri-transformation/agri-food excluding grain transport, waste collection and treatment, sawmills, wool industry, medical/veterinary/research sectors, cigarette/cigar manufacture and paper factory.
‡Highly exposed group included dairy farms, cattle, poultry, pigs, work with grains and transport and cotton industry. §OR adjusted for age at interview, department, sex, Comprehensive Smoking Index (CSI), number of job periods, education and occupational exposure to asbestos. The never exposed to endotoxins are always the reference group.
¶Never means having no job in work environment group potentially exposed to endotoxin.,
**Ever means having held at least one job in work environment group potentially exposed to endotoxins.
††Cumulative exposure was transformed into qualitative variables according to quartiles of distribution among controls in each group: quartile 1 ([0–1012]; [0–380]; [4602–12560]); quartile 2 ([1012–7670]; [380–940]; [12560–40820]); quartile 3 ([7670–58090]; [940–2874]; [40820–87920)); quartile4 (>58090; >2874; >87 920) UE* years, respectively, for total, weakly and highly exposed to endotoxins.