Table 5

Incidence rate ratios (IRR) and 95% CIs for lung cancer related to log-transformed cumulative exposure to cristobalite, SiC fibres and SiC particles among 1166 male ever-smoking Norwegian long-term SiC industry workers employed during 1913–2003 and followed up during 1953–2008, adjusted for age and the other exposure factors

Smokers, N=1166, 30714 PYR, 58 cases
IRR95% CILR-test*AICrPearson†
Cristobalite1.91.2 to 2.9275.6
 Cristobalite adjusted for SiC2.01.2 to 3.3p=0.8277.50.74
 Cristobalite adjusted for SiC and fibres1.60.8 to 3.3p=0.4278.8
 Cristobalite adjusted for fibres1.50.8 to 2.9p=0.4276.90.76
 Cristobalite adjusted for fibres and SiC1.60.8 to 3.3p=0.8278.8
Fibres1.91.2 to 2.9276.7
 Fibres adjusted for SiC1.71.1 to 2.9p=0.6278.40.51
 Fibres adjusted for SiC and cristobalite1.30.7 to 2.6p=0.2278.8
 Fibres adjusted for cristobalite1.30.7 to 2.6p=0.2276.90.76
 Fibres adjusted for cristobalite and SiC1.30.7 to 2.6p=0.8278.8
SiC1.41.0 to 2.1281.4
 SiC adjusted for fibres1.10.7 to 1.8p=0.03278.40.51
 SiC adjusted for fibres and cristobalite0.90.5 to 1.6p=0.2278.8
 SiC adjusted for cristobalite0.90.5 to 1.6p=0.02277.50.74
 SiC adjusted for cristobalite and fibres0.90.5 to 1.6p=0.4278.8

  • ↵* LR-test: Likelihood ratio test comparing the actual model with the model containing one less exposure factor.

  • ↵† rPearson: Pearson's correlation coefficient.

  • PYR, person - years; AIC, Akaike's Information Criterion; SiC, silicon carbide.