Table 6.

Interactions between Occupational Silica Exposure and Smoking for All Lung Cancers

Exposure Status	All Lung Cancers
	Control Subjects (n)	Cases (n)	OR*	95% CI
Never-smoker and never silica	5,900	1,121	1.0	Referent
Never-smoker and ever silica	1,253	248	1.02	0.87–1.19
Ever-smoker and never silica	10,577	10,857	6.37	5.91–6.87
Ever-smoker and ever silica	3,235	4,675	8.72	8.0–9.52
P value multiplicative interaction			<0.01
RERI			2.34	1.85–2.83

Definition of abbreviations: CI = confidence interval; OR = odds ratio; RERI = relative excess risks due to interaction.

^*OR adjusted for sex, study, age group, and list A jobs.