Standardised mortality ratios (SMR) and Poisson regression analyses (incidence rate ratios, IRR) with 95% CIs of obstructive lung diseases as underlying (OLD-u) or underlying or contributing (OLD-uc) cause of death 1951–2007, by cumulative exposure groups, among Norwegian long-term silicon carbide industry workers employed 1913–1920
| All employees (N=1687) | All ever-smokers (N=1162) | <15 years employment, ever-smokers (N=1115) | ≥15 years employment, ever-smokers (N=599) | ||||||||||||
| OLD-u (45 cases) | OLD-u (38 cases) | OLD-uc (55 cases) | OLD-uc (32 cases) | OLD-uc (23 cases) | |||||||||||
| SMR | 95% CI | IRR* | 95% CI | Ptrend | IRR* | 95% CI | Ptrend | IRR* | 95% CI | Ptrend | IRR* | 95% CI | Ptrend | ||
| Total dust | |||||||||||||||
| Low | 0–28.6 mg×years/m3 | 1.4 | 0.7 to 2.8 | 1.0 | – | – | 1.0 | – | – | 1.0 | – | – | 1.0 | – | – |
| Medium | 28.7–86.1 mg×years/m3 | 2.6 | 1.6 to 4.2 | 2.8 | 0.9 to 8.5 | – | 1.7 | 0.7 to 4.1 | – | 1.3 | 0.5 to 3.4 | – | 2.2 | 0.2 to 24.5 | – |
| High | ≥86.2 mg×years/m3 | 1.9 | 1.2 to 2.9 | 2.5 | 0.8 to 7.4 | p=0.2 | 2.4 | 1.0 to 5.5 | p=0.03 | 2.3 | 0.8 to 6.4 | p=0.1 | 5.4 | 0.7 to 40.1 | p=0.05 |
| Respirable dust | |||||||||||||||
| Low | 0–3.7 mg×years/m3 | 1.5 | 0.8 to 2.8 | 1.0 | – | – | 1.0 | – | – | 1.0 | – | – | 1.0 | – | – |
| Medium | 3.8–9.9 mg×years/m3 | 2.7 | 1.7 to 4.3 | 2.0 | 0.8 to 5.1 | – | 1.2 | 0.6 to 2.7 | – | 1.0 | 0.4 to 2.5 | – | 1.2 | 0.2 to 8.7 | – |
| High | ≥10 mg×years/m3 | 1.8 | 1.1 to 2.9 | 1.5 | 0.6 to 3.9 | p=0.5 | 1.6 | 0.8 to 3.3 | p=0.2 | 1.7 | 0.7 to 4.6 | p=0.3 | 2.4 | 0.6 to 10.2 | p=0.2 |
| Fibre | |||||||||||||||
| Low | 0–0.5 fibres×years/cm3 | 1.9 | 1.1 to 3.4 | 1.0 | – | – | 1.0 | – | – | 1.0 | – | – | 1.0 | – | – |
| Medium | 0.6–2.0 fibres×years/cm3 | 1.9 | 1.1 to 3.3 | 0.9 | 0.4 to 2.3 | – | 0.7 | 0.3 to 1.5 | – | 0.6 | 0.2 to 1.3 | – | 1.8 | 0.3 to 9.8 | – |
| High | ≥2.1 fibres×years/cm3 | 2.1 | 1.3 to 3.2 | 1.4 | 0.6 to 3.1 | p=0.4 | 1.2 | 0.6 to 2.2 | p=0.5 | 1.2 | 0.5 to 2.8 | p=0.8 | 2.6 | 0.6 to 11.4 | p=0.2 |
| Silicon carbide dust | |||||||||||||||
| Low | 0–0.7 mg×years/m3 | 0.9 | 0.4 to 2.0 | 1.0 | – | – | 1.0 | – | – | 1.0 | – | – | 1.0 | – | |
| Medium | 0.8–2.6 mg×years/m3 | 2.8 | 1.7 to 4.4 | 3.1 | 1.0 to 9.3 | – | 1.9 | 0.8 to 4.4 | – | 1.7 | 0.6 to 4.4 | – | 2.4 | 0.5 to 12.1 | – |
| High | ≥2.7 mg×years/m3 | 2.2 | 1.4 to 3.4 | 3.4 | 1.2 to 10.2 | p=0.03 | 2.5 | 1.1 to 5.5 | p=0.02 | 2.9 | 1.1 to 7.6 | p=0.03 | 2.9 | 0.7 to 12.8 | p=0.2 |
| Quartz | |||||||||||||||
| Low | 0–13.7 μg×years/m3 | 2.0 | 1.2 to 3.5 | 1.0 | – | – | 1.0 | – | – | 1.0 | – | – | 1.0 | – | – |
| Medium | 13.8–50.3 μg×years/m3 | 1.7 | 0.9 to 3.1 | 0.7 | 0.3 to 1.8 | – | 0.9 | 0.4 to 2.0 | – | 0.8 | 0.3 to 1.9 | – | 1.9 | 0.2 to 17.0 | – |
| High | ≥50.4 μg×years/m3 | 2.1 | 1.4 to 3.3 | 1.3 | 0.6 to 2.8 | p=0.4 | 1.5 | 0.8 to 3.0 | p=0.2 | 1.4 | 0.6 to 3.2 | p=0.4 | 4.3 | 0.6 to 32.0 | p=0.06 |
| Cristobalite | |||||||||||||||
| Low | 0–10.3 μg×years/m3 | 1.7 | 0.9 to 3.0 | 1.0 | – | – | 1.0 | – | 1.0 | – | 1.0 | – | – | ||
| Medium | 10.4–47.6 μg×years/m3 | 1.8 | 1.0 to 3.0 | 0.7 | 0.3 to 1.9 | – | 0.6 | 0.3 to 1.4 | – | 0.7 | 0.3 to 1.7 | – | 0.9 | 0.2 to 4.8 | – |
| High | ≥47.7 μg×years/m3 | 2.4 | 1.6 to 3.7 | 1.6 | 0.7 to 3.4 | p=0.2 | 1.7 | 0.9 to 3.2 | p=0.05 | 1.4 | 0.6 to 3.1 | p=0.4 | 3.2 | 0.7 to 14.0 | p=0.02 |
↵* Adjusted for age (</≥75 years) and period of diagnosis (</≥1 January 1990).