Table 1

Mean years of employment with SD, and geometric mean (GM), geometric SD (GSD) and estimated arithmetic mean (AM) of annual intensity of exposure to specific exposure factors, by department and period of employment, for 1687 male long-term Norwegian silicon carbide industry workers employed during 1913–2003

Employment before 1960Employment after 1959
GMGSDAM*GMGSDAM*
Furnace department (n)232584
Years of exposure (mean/SD)7.2 (6.4)9.5 (7.3)
Total dust (mg/m3)9.33.1183.83.17.1
Respirable dust (mg/m3)1.12.51.60.552.50.84
Respirable quartz (mg/m3)0.0153.40.0330.00453.50.0096
Respirable cristobalite (mg/m3)0.0146.30.0740.00224.60.0072
Respirable SiC (mg/m3)0.124.80.410.0645.40.27
Fibres (fibres/cm3)0.333.10.620.202.60.31
Processing department (n)166537
Years of exposure (mean/SD)9.4 (8.3)9.5 (7.3)
Total dust (mg/m3)122.1165.22.27.2
Respirable dust (mg/m3)1.02.31.40.602.20.82
Respirable quartz (mg/m3)0.00562.30.00780.00322.20.0044
Respirable cristobalite (mg/m3)0.00752.30.0110.00192.20.0026
Respirable SiC (mg/m3)0.672.91.20.342.70.55
Fibres (fibres/cm3)0.0572.50.0880.0302.50.047
Maintenance department (n)187453
Years of exposure (mean/SD)9.6 (9.1)10.3 (7.8)
Total dust (mg/m3)5.61.96.93.52.14.7
Respirable dust (mg/m3)0.551.80.650.522.10.68
Respirable quartz (mg/m3)0.00391.80.00460.00352.10.0047
Respirable cristobalite (mg/m3)0.00381.80.00460.00182.10.0023
Respirable SiC (mg/m3)0.171.90.200.122.00.15
Fibres (fibres/cm3)0.191.90.230.102.40.14
Other, low exposed (n)88276
Years of exposure (mean/SD)12.3 (10.7)11.6 (8.7)
Total dust (mg/m3)0.223.80.530.113.50.24
Respirable dust (mg/m3)0.0213.70.0480.0153.40.031
Respirable quartz (mg/m3)0.000203.70.000470.000113.40.00023
Respirable cristobalite (mg/m3)0.000253.80.000620.000473.60.0011
Respirable SiC (mg/m3)0.00773.70.0180.00503.30.010
Fibres (fibres/cm3)0.00723.40.0150.00443.30.0088
  • * AM estimated from GM and GSD, as described by Seixas et al,12 using the formula AM=GM*exp (0.5(ln GSD)2).

  • n, Number of workers. The sum of n is more than 1687, as each person may have been employed in several departments and in both periods.