Table 2

Observed number of cases (Obs) and incidence rate ratio (IRR) with 95% CIs of lung cancer among 1687 male Norwegian long-term silicon carbide industry workers employed during 1913–2003 and followed up during 1953–2008, by department affiliation and adjusted for age and smoking status

	All long-term workers							Ever-smokers
	n	Person-years	Obs	IRR^*	95% CI	IRR^†	95% CI	n	Person-years	Obs	IRR^‡	95% CI
Department
Other, low exposed	175	5082	3	ref		ref		96	2960	3	ref
Furnace	387	9405	20	3.8	1.1 to 13	2.6	0.8 to 8.7	294	7543	20	2.5	0.7 to 8.4
Processing	347	7867	9	2.1	0.6 to 7.8	1.6	0.4 to 5.9	241	5696	7	1.3	0.3 to 4.9
Maintenance	313	8043	9	2.0	0.5 to 7.5	1.5	0.4 to 5.7	213	5820	8	1.4	0.4 to 5.4
Mixed	465	12 512	21	2.9	0.9 to 9.6	2.2	0.7 to 7.5	322	8695	20	2.1	0.6 to 7.1
Smoking
Never-smokers	358	9257	1	ref		ref
Ever-smokers	1166	30 714	58	20.9	2.9 to 151	18.9	2.6 to 137
Unknown smoking	163	2939	3	7.6	0.8 to 73	7.3	0.8 to 71

↵* Adjusted for age (≤54/55–74/≥75 years).
↵† Adjusted for age (≤54/55–74/≥75 years) and smoking status or department.
↵‡ Ever-smokers only (n=1166), adjusted for age (≤54/55–74/≥75 years).
ref; reference.