The HRs for silica were,
respectively, 4.5 (95% CI 0.3 to 59) and 3.5 (95% CI 1.9 to 13) for 1–9 years’ and ≥10
years’ exposure.
We also observed an excess risk related to ≥10 years’ exposure to
formaldehyde (HR 2.1, 95% CI 0.4 to 11) that was based on very small numbers of exposed
cases (N=2) and non-cases (N=5).
DISCUSSION