Table 1

 Demographic and exposure characteristics of lung cancer cases and non-cases in a cohort of diatomaceous earth workers exposed to silica

Lung cancer casesNon-cases
*Time varying covariates were computed for each subject at the end of follow up.
†534 subjects were not eligible for risk sets because they either died or were censored at an earlier age than the minimum age of lung cancer death.
Number of subjects772265†
Hispanic ethnicity; n (%)4 (5.2%)542 (23.9%)
Calendar year of death; mean (SD)1978 (10.4)
Year of hire; mean (SD)1944 (10.9)1954 (14.0)
Age at hire; mean (SD)30.4 (9.3)26.7 (8.0)
Duration of follow up (y)*; mean (SD)30.1(9.9)28.1 (14.5)
Duration of work (y)*; mean (SD)13.6 (13.3)10.7 (11.4)
Cumulative silica exposure (mg/m3-y)*
    Mean (SD)4.3 (5.8)2.1 (3.4)
        50th centile2.31.1
        75th centile5.82.4
        99th centile32.115.7