Table 5

 Relative risks (RR) and 95% confidence intervals (CI) for lung cancer mortality, adjusted for age and smoking, in male German carbon black workers traced alive on 1 January 1976

Variable with levelsAll workers, main (census) cohortWorkers hired 1960 or later, inception cohort
DeathsRR95% CIRR95% CI
Period of hiring (calendar time)
    <195040.300.10–0.87
    1950–5960.290.12–0.72
    1960–69311.00311.00
    1970–7991.450.64–3.2891.700.73–3.96
    1980–9700
    Trend (10 years)1.611.14–2.281.060.54–2.09
Age at hiring (years)
    ⩽2551.0021.00
    >25–35121.220.42–3.55101.850.39–8.80
    >35–45192.100.72–6.07172.030.40–10.39
    >45142.740.85–8.85111.560.25–9.77
    Trend (10 years)1.461.03–2.051.030.64–1.67
Time since hiring (years), time dependent
    >0–1571.0071.00
    >15–25150.680.26–1.77150.630.24–1.65
    >25280.490.18–1.34180.560.20–1.57
    Trend (10 years)0.730.47–1.120.790.50–1.25
Years of employment, time dependent
    1–5121.00121.00
    >5–1090.920.37–2.2581.050.40–2.74
    >10–20160.700.30–1.61130.840.34–2.09
    >20130.390.16–0.9470.960.33–2.81
    Trend (10 years)0.700.52–0.940.970.66–1.43
At least 1 year employment in lamp or furnace black
    No281.00221.00
    Yes221.480.84–2.61181.040.56–1.96
At least 1 year employment in gas black
    No371.00321.00
    Yes131.070.57–2.0281.210.55–2.64
At least one year employment in preparation plant
    No461.00361.00
    Yes41.050.37–2.9541.070.38–3.03
At least one year employment in heavily exposed jobs
    No161.00141.00
    Yes341.290.71–2.34260.980.51–1.89
Average carbon black exposure (carbon black scores per year), time dependent
    0–1121.0091.00
    >1–2141.060.49–2.28141.530.66–3.55
    >2–3210.970.47–1.98151.130.49–2.60
    >330.390.11–1.3920.400.09–1.86
    Trend (1 unit)0.850.65–1.100.860.64–1.15
Cumulative carbon black exposure, time dependent
    0–5101.0091.00
    >5–10101.070.44–2.5980.970.37–2.54
    >10–2090.840.34–2.1091.030.40–2.67
    >20–40120.700.29–1.70121.270.52–3.08
    >4090.280.11–0.7220.210.04–0.99
    Trend (10 units)0.790.68–0.9190.840.69–1.01
Total5040