Table 1.

Lung cancer incidence by cumulative exposure to endotoxin ^*

	Cumulative endotoxin exposure †
Exposure lag time	Unexposed	≤1283	>1283 to ≤2056	>2056 to ≤2801	>2801 to ≤4075	>4075	P trend ‡
None
HR (95% CI)	1.00 (ref)	1.06 (0.79 to 1.41)	0.98 (0.74 to 1.31)	0.79 (0.59 to 1.07)	0.88 (0.66 to 1.17)	0.71 (0.52 to 0.95)	.004
No. of case patients/No. of control subjects	186/913	88/425	89/424	75/425	90/424	74/424
5-y lag
HR (95% CI)	1.00 (ref)	1.08 (0.82 to 1.44)	0.95 (0.72 to 1.28)	0.79 (0.59 to 1.07)	0.91 (0.68 to 1.20)	0.69 (0.51 to 0.93)	.003
No. of case patients/No. of control subjects	186/916	94/456	86/424	74/407	91/416	71/416
10-y lag
HR (95% CI)	1.00 (ref)	1.07 (0.81 to 1.41)	0.93 (0.70 to 1.25)	0.78 (0.58 to 1.06)	0.91 (0.68 to 1.21)	0.70 (0.51 to 0.95)	.005
No. of case patients/No. of control subjects	188/923	99/507	84/422	72/387	89/400	70/396
15-y lag
HR (95% CI)	1.00 (ref)	1.07 (0.82 to 1.40)	0.88 (0.66 to 1.18)	0.85 (0.63 to 1.14)	0.87 (0.64 to 1.17)	0.72 (0.52 to 0.98)	.008
No. of case patients/No. of control subjects	193/965	106/555	83/402	77/366	76/372	67/375
20-y lag
HR (95% CI)	1.00 (ref)	1.00 (0.78 to 1.29)	0.75 (0.56 to 1.00)	0.87 (0.64 to 1.17)	0.88 (0.63 to 1.23)	0.74 (0.53 to 1.02)	.03
No. of case patients/No. of control subjects	208/1090	122/541	81/410	76/343	56/312	59/339

^*Data were adjusted for age at baseline (continuous) and smoking status (never [ref], former, or current). Analysis was based on cumulative exposure to endotoxin at each risk set time, excluding subjects who ever worked as machinists (n = 114), worked with wool (n = 17), or worked in sanitation jobs in production (n = 44). CI = confidence interval; HR = hazard ratio; ref = referent.

^†Exposure categories represent quintiles of exposure among noncase patients with no exposure lag. Cumulative endotoxin exposure is expressed as (endotoxin units/cubic meter) × years.

^‡Two-sided Wald test for the hypothesis that the slope equals zero of hazard trend (treated as a continuous variable), including unexposed category. Category scores were based on the median of category exposure range.