Table 1

Characteristics of the study population

Type of exposure*
Rock drills (RD)Impact wrenches (IW)No exposure to RD or IW
Age (years), mean (SD)40.1 (13.1)42.7 (12.7)33.7 (11.1)
Body mass index (kg/m2), mean (SD)26.1 (2.8)28.8 (3.8)28.3 (5.8)
Smoking or tobacco snuffing, n (%)23 (70)29 (56)8 (42)
Cotinine (ng/mL), mean (SD)446 (417)331 (444)177 (260)
CDT (%), mean (SD)0.7 (0.5)0.7 (0.2)0.7 (0.1)
HbA1c, mean (SD)5.3 (0.3)5.2 (0.3)5.3 (0.5)
Vibration exposure level (m/s2)177NA†
Vibration exposure (min/day)4715NA†
Vibration exposure (hour·m/s2), mean (SD)13 219 (25 144)2209 (2631)1†
Vibration exposure (years), mean (SD)11.4 (11.6)15.4 (13.8)NA†
Finger/hand injuries (%)6 (18)7 (13)3 (16)
Vibration white fingers (%)‡6 (18)0 (0)0 (0)
Finger numbness (%)12 (36)7 (13)5 (26)
  • *n=6 had been exposed both to rock drills and to impact wrenches. These individuals are included in the table as exposed to rock drills. Information on total years of vibration was missing for one worker in the other work group. Blood samples were missing for two rock drill operators, seven impact wrench operators and one in the no exposure group.

  • †No exposure to hand–arm vibration (HAV) or rare/occasional exposure from other tools than rock drills or impact wrenches. To enable log transformation, zero exposure to the main tools was substituted with hour·m/s2=1.

  • ‡Diagnosed by an occupational medical doctor.

  • CDT, carbohydrate-deficient transferrin; NA, not applicable.